JPH0693729B2 - Multicolor image reader - Google Patents

Description

The present invention relates to an image reading apparatus having a plurality of solid-state image sensors used in a digital color copying machine or the like.

Generally, in a digital color copying machine or the like that uses an image reading device equipped with a solid-state image sensor such as a charge-coupled device (hereinafter abbreviated as CCD), the image reading device is generally used as a light source as shown in FIG. The reflected light emitted from the color document 2 on the platen glass 1 by the halogen lamp 3 is mirrors 4,5,6 near infrared light cut visible light transmission filter 7, imaging lens 8 and color separation of blue, green and red. Solid-state image sensor through the filter group 9, for example
The light is focused on the CCD 10 to form read image data.

Further, as shown in FIG. 2, the image data formed as described above are sequentially transferred line by line in synchronization with the clock pulse from the oscillator 11, amplified by the level shift circuit 12, and then transferred to the analog It is converted into digital image data by a digital converter 13, compared with a predetermined dither pattern by a dither circuit 14 and encoded, and then temporarily stored in a buffer memory 15.

In this type of conventional image reading device, a large amount of light is required for the light source, which increases power consumption, increases the size of the device,
There was a problem of increased heat generation.

For example, a halogen lamp is generally used as the light source of the device shown in FIG. 1 because it is easier to obtain a large amount of light than a fluorescent lamp and has high stability, but the spectral sensitivity of the CCD10 is shown by the solid line in FIG. As shown in the characteristics, the sensitivity to light in the blue wavelength range (hereinafter referred to as blue light) in the visible light range is low, and the spectral energy distribution of the halogen lamp shown in the characteristics of the broken line is also on the short wavelength side of blue light. Since it is significantly deviated to the longer wavelength side, when a halogen lamp, an optical system, and a CCD are combined to perform color separation exposure on the original to make the output levels for each color component of the CCD uniform, color separation of the blue component of the original is performed. A large amount of lamp power was required for exposure.

For example, when reading the document information by sub-scanning the longitudinal (297 mm) direction of an A4 size color document, two 2592-element CCDs are provided in the main scanning direction to obtain 16 Pel resolution in the sub-scanning direction and the main scanning direction. When reading the A4 longitudinal direction by dividing it into two parts, the halogen lamp power for exposing color originals to the blue, green and red color separation exposures is 1.2K each.
W, 0.6KW, 0.7KW was required. That is, the color separation exposure of the blue component of the color original requires about twice as much lamp power as the color separation exposure of each of the green component and the red component, reducing power consumption, downsizing the device, and reducing heat generation. It was a big problem in trying.

In view of the above points, the present invention has been made in order to improve the above-mentioned drawbacks, and in order to read color separation image light from a multicolor original, there are three types provided corresponding to each color of blue, red and green. In a multi-color image reading apparatus having a solid-state image sensor, the light receiving areas of the three solid-state image sensors are substantially the same, the number of pixels of the solid-state image sensor corresponding to blue is X, and the number of pixels of the solid-state image sensor corresponding to red. Y,
When the number of pixels of the solid-state image sensor corresponding to green is Z, the solid-state image sensor has a function of X <Y <Z, and a driving unit for driving the solid-state image sensor is separately provided for each of the three solid-state image sensors. It is an object of the present invention to provide a multicolor image reading device characterized by the above.

An embodiment of a multicolor image reading device according to the present invention will be described below with reference to the drawings.

FIG. 4 shows a three-color separation prism optical system which replaces the color separation optical system 10 'of the reading portion of the image reading apparatus shown in FIG. In FIG. 4, a light image W after illuminating a color original with a light source such as a halogen lamp
Is a near-infrared light cut visible light transmitting filter 7 and an image forming lens 8 and passes through three different separating prism systems 16, 17, 18 composed of dichroic mirrors, etc., and separates blue, green and red separated lights. Divided into statues B, G, and R. CCD19,20,21 are blue,
This is for reading B, G, and R, which are the separated color images of green and red, respectively. In place of the optical system 10 'of the reading portion of the image reading apparatus shown in FIG. 1, the three-color splitting prism optical system shown in FIG. A reading optical system is configured.

Generally, full-color hardcopy images are yellow,
It is composed of three primary colors of magenta and cyan, and color reproduction is performed by so-called subtractive color mixing. Of the three primary colors, magenta is the color that has the greatest visual impact in subjective evaluation of color definition, and cyan and yellow are next in that order. That is, yellow has the least effect on color definition.

Further, when comparing the sensitivities (represented by saturated exposure amount) of CCDs and the like with the exposure storage time kept constant, the number of pixels of CCDs and the sensitivities are generally inversely proportional in a constant light receiving area. That is, CCD
When the number of pixels of is doubled, the sensitivity tends to be halved.

Therefore, based on the number of pixels such as CCD for reading the image of magenta component that has the greatest effect on color definition, the number of pixels of CCD or the like that reads the image of cyan component that has the next smallest influence or the image of yellow component that follows it. By increasing the sensitivity by reducing the number of images, and outputting the image information read to a color laser beam printer, etc., without degrading the substantial color definition of the full-color image, blue or red color separation exposure It is possible to reduce the power consumption of the light source and the number of pixels of the CCD used.

Here, the light receiving areas of the three CCDs (solid-state image sensors) are almost the same, and the CCD for obtaining the image signal for the yellow component, that is, the CCD 19 for the blue color-separated light image has 2240 pixels. CC for obtaining image signals for magenta and magenta components
The number of pixels of D, that is, the CCD 20 for the green color-separated light image is 3360, and the number of pixels of the CCD for obtaining the image signal for the cyan component, that is, the CCD 21 for the red color-separated light image is 2655. Note that the number of pixels of the CCD in this case is for reading by scanning the longitudinal direction of the A4 size color original document in the sub-scanning direction.
Pixel array direction) and sub-scanning direction image resolution is 16
It is based on Pel. In this case, the sensitivity for blue light is about 1.5 times, and the sensitivity for red light is about 1.3 times, compared to the case where CCDs of the same number of pixels, that is, 3360 CCDs, are used for CCDs 19, 20, and 21, respectively.

Also, since the light receiving areas of the three CCDs are almost the same, naturally,
The light-receiving area per pixel of the CCD for the color-separated light image of green is essentially small, followed by red and blue.

Therefore, when 3360 elements are used for the CCD for receiving the color separated light image of each of the blue component, the green component, and the red component, that is, the CCD for obtaining the image signal of the yellow component, the magenta component, and the cyan component, the color original document is used. The power required by the halogen lamp for each color separation exposure of the blue component, green component, and red component is 1.2K each.
Whereas W, 0.6 KW, and 0.7 KW were required, in the device of this example, the electric power of the halogen lamp could be reduced to 0.8 KW, 0.6 KW, and 0.55 KW, respectively.

FIG. 5 is a block diagram showing an embodiment of the signal processing system of the multicolor image reading apparatus according to the present invention. 16,17,18
Is a simplified representation of the color separation prism using the dichroic mirror shown in FIG. 4, and 19,20,21 are the color separation solutions of the blue, green and red components shown in FIG. When reading A4 size color originals with CCDs that receive light images, the number of pixels for each is 22 as described above.
They are 40, 3360 and 2655. These CCDs 19, 20, 21 include known amplifiers 25, 26, 27, analog / digital converters (hereinafter referred to as A / D converters) 31, 32, 33, dither circuits 34, 35, 3
6. The image memories 37, 38, 39 and the buffer memory 43 are connected in this order. It is also controlled by the sequence controller 47. CCD drive circuit 2 for CCD drive
2,23,24 are connected to CCD 19,20,21 respectively. Further CCD
The drive circuits 22, 23, 24 give drive clocks CLK “A”, CLK “B”, CLK “C” to the A / D converters 31, 32, 33, respectively, and the dither circuits 34, 35, 36 respectively. The horizontal sync signals Hs “A”, Hs “B”, and Hs “C” are given, and the horizontal sync signals are sent to the image memories 37, 38,
Memory controller 40, 41, 42 connected to 39 respectively
Given to. In addition, these memory controllers 40, 4
The vertical sync signal (V
s) are connected as given. A laser beam printer (hereinafter abbreviated as LBP) 44 is connected to the output side of the buffer memory 43, and the LBP 44 mainly has a laser driver 45 and a semiconductor laser 46 having a D / A converter on the input side. Further, it comprises a deflector 49 and an electrophotographic process device 48 for performing a known electrophotographic process. The LBP 44 and the buffer memory 43 are controlled by the sequence controller 47. FIG. 6 is a diagram showing the time chart of the circuit shown in FIG. 5, and FIG. 7 is a diagram showing the input / output characteristics of the semiconductor laser.

Next, the operation of one embodiment of the multicolor image reading apparatus according to the present invention will be described with reference to FIGS. 4 to 7.

A color document (not shown) (for example, A4 size) is exposed by a halogen lamp (not shown) for each color and scanned (including main scanning and sub scanning) by a scanning mechanism (not shown). The scanning mechanism shown can be used.). The optical image W at this time is divided into three different prism systems 16,1
It passes through 7,18 and is divided into various resolved light images B, G, and R of blue, green, and red. In this case, the halogen (not shown) requires 0.8 KW for blue component color separation scanning, 0.6 KW for green component color separation scanning, and 0.55 KW for red component color separation scanning. . The color-separated light images B, G, and R are blue component light images B on the CCD 19 surface of 2240 elements, and the green component light image G is the light of red components on the CCD 20 surface of 3360 elements. Statue R is 265
Images are formed on the CCD21 surface, which has five elements. Each CCD 19,20,2
Among the CCDs 1 corresponding to the color separation, the CCD drive circuits 22, 23, 24 for transmitting the timing signal for holding the accumulated charges by the optical image of one line, the charge transfer clock, etc., respectively, are the CCD 19,
A CCD drive circuit provided individually for each of 20 and 21 and corresponding to the exposure scan for each color separation performs the drive corresponding to each color separation scan.

The drive clocks CLK “A”, CLK from which the video signals VS of the respective color components are output from the corresponding CCD drive circuits 22, 23, 24 from the outputs corresponding to the respective color separation scans of the respective CCDs 19, 20, 21
Read corresponding to "B", CLK "C". For example, in order to obtain an image signal of a yellow component from a light image of a blue component, a color original is scanned and exposed by a halogen lamp (not shown) using 0.8 KW of electric power, and the light image of the blue component is CCD19.
It is received by the CCD, and the accumulated charge of CCD 19 by this is CCD drive circuit.
22 Drives the video signal VS using the clock CLK “A”.
Is read as. The same applies to the next exposure scan of the color original to obtain the video signal VS for the magenta image signal, and to the next exposure scan of the color original to obtain the video signal VS for the cyan component image signal. Obtained.

This successively output video signal VS is the amplifier 25, 26, 27
A / D of the latter stage in the amplifier corresponding to color separation scanning in
It is amplified to an appropriate voltage value for the corresponding A / D converter of the converter 31, 32, 33, and its gain and dynamic range are adjusted by the corresponding variable volume of the variable volume 28, 29, 30. . In the A / D converter corresponding to color separation scanning among the A / D converters 31, 32, 33, the input drive clock-synchronized analog video signal VS is sampled by the drive clock, and an 8-bit digital signal is output. Quantize into a signal. In this driving clock, the pixel densities of the CCDs 19, 20, and 21 of the color separation scans of the blue component, the green component, and the red component are different, so the cycle is also different as shown in FIG. 6, and the CCD driving circuit 22 and 2
It is made by 3,24 and serves as the sampling clock of each of the A / D converters 31,32,33. Where Hs “A”, Hs “B”,
Hs "C" indicates a synchronization clock as a horizontal synchronization signal used for color separation of blue, green, and red color components, and its period is T. In addition, CLK “A”, CLK “B”, CLK “C” also indicate driving clocks for the blue component, green component, and red component, respectively, and their cycles are about T / 2240, about T / 3360, about T. It is / 2655.

In this embodiment, the output of the printer is basically LBP44, and the LBP44 uses the semiconductor laser 46 as a laser light source. The semiconductor laser 46 has a steep input / output characteristic as shown in FIG. 7, and because the characteristic moves in the direction of the arrow even with ambient temperature, it is difficult to modulate the luminance of the input video signal. Therefore, it is well known that it is difficult to express halftone.

Therefore, in this embodiment, in order to reproduce the halftone, A /
Of the dither circuits 34, 35 and 36, the 8-bit quantized digital signal A / D converted by one of the D converters 31, 32 and 33 is
By applying dither matrix in a dither circuit corresponding to color separation scanning, halftone reproduction is performed by combining dots of color components and non-color components. Since a specific dither method is a well-known method, detailed description will be omitted.

The color component quantized video signal VS by color separation exposure scanning of the color original is the dither circuit 34, 35, 3 corresponding to the color component.
After being dithered by the dither circuit in 6, "1",
The image data of the quantized digital signal of "0" is stored in the corresponding image memory of the image memories 37, 38, 39 through the corresponding memory controller of the memory controllers 40, 41, 42.

For example, here, the video signal VS sequentially obtained as described above by the color separation exposure scanning of the blue component is amplified by the amplifier 25, and then the A / D converter 31 drives the driving clock CLK "A" from the CCD driving circuit 22. After being converted to an 8-bit digital signal by using ", and then subjected to dithering by the dither circuit 34, a quantized digital signal of" 1 "and" 0 ", that is,
Memory controller as image signal for yellow component
It is stored in the image memory 37 via 40.

Next, the image signal for the magenta component is similarly processed through the CCD 20 by the next exposure scan of the color original document and the image memory 3
Similarly, the image signal for the cyan component is also stored in the image memory 39 via the CCD 21 by the next exposure scanning of the color original. Here, each image memory 3 for the image signal of each component of yellow, magenta, and cyan
The capacity of 7,38,39 is, for example, 2240 if you read the image longitudinal feed direction with a resolution of 16Pel with a CCD arrayed in the direction perpendicular to the longitudinal direction (length 297 mm) of an A4 size color original. 2240 in the case of image memory 37 corresponding to the CCD 19 of the element (in the case of image signal memory for yellow component)
(Number of elements) x 297 (length) x 16 (resolution) ≈ 1.06 Mbytes of memory capacity is required, and in the case of image memory 38 corresponding to a CCD 20 of 3360 elements (of the image signal memory for the magenta component In the case of the image memory 39 corresponding to the 2655-element CCD21 (in the case of the memory for the image signal for the cyan component), similarly, the capacity of 3360 × 297 × 16 ≈ 1.6 MB is required. A capacity of 297 x 16 ≈ 1.26 Mbytes is required.

However, in this case, the CCD with the highest image density has 3360 pixels, and the memory capacity for this is approximately
Since it is 1.6 Mbytes, if the pixels of each CCD corresponding to the color-separated light image of the blue component and the red component are unified as in the conventional case, the total image memory capacity will be
1.6M bytes x 3 ≈ 4.8M bytes. However, even if the pixel densities of the CCDs 19 and 21 corresponding to the color-separated light images of the blue component and the red component are roughened as described above, the LB
The color definition of the image printed out by P44 etc. is
Visually the same as that of an image formed using a memory having a capacity of about 4.8 MB as in the past,
Therefore, the image printed out by this embodiment can maintain substantially the same color definition as compared with the conventional image. Moreover, in the case of this embodiment, the total capacity of the image memories 37, 38, 39 for storing image data is 1.06 + 1.6 + 1.26≈3.9.
2M bytes, which is about 3.92 / 48 × 100 when compared with the total memory capacity used in conventional devices, that is, about 4.8M bytes.
≒ 80%, which means that 20% of the memory capacity can be reduced.

The image data for each color stored in the image memories 37, 38, 39 is transferred to the buffer memory 43 in any necessary order by one of the memory control circuits 40, 41, 42, and by the laser driver 45 in the LBP 44. The laser beam of the driven semiconductor laser 46 is turned on and off. The modulated laser light is processed by the electrophotographic process device 48 for each color through the polarizer 49 in accordance with the well-known electrophotographic process. The LBP44 in the block diagram used in this embodiment is
Is controlled by the sequence controller 47 to read one page of image data from the image memory 37, and a yellow image, which is a complementary color of blue,
The image data for one page is read from the image memory 38, and superimposed on the yellow image already printed on the paper,
Finally, the magenta image, which is the complementary color of green, is similarly read from the image memory 39, and the cyan image, which is the complementary color of red, is printed out by superimposing it on the superimposed yellow and magenta images. The image of the color corresponding to the original is reproduced.

Note that the above system operation is controlled by the sequence controller 47, and the exposure of the deflection device 49 of the LBP 44 and the electrophotographic process device 48 and the control of the operation associated therewith,
The sequence controller 47 controls the image timing signal and the printing operation of the LBP 44.

The image data read by the device shown in FIG.
When outputting to P44 to obtain a full-color hard copy image, the pixel densities in the scanning direction of the solid-state image sensor for each color image of yellow, magenta, and cyan are 10.7 dot / mm, 16 dot / mm, and 12.6 dot / mm, respectively. It was. This image shows the case where the pixel densities of the solid-state image sensors for yellow magenta and cyan are both aligned to 16 dots / mm, and the pixel density of the optical system in the sub-scanning direction is 16 dots / m.
The visual color sharpness was almost comparable to that of the image with m. There was no problem with image quality such as color reproducibility, gradation, and image density.

When the number of pixels is reduced, the resolution at the time of reading decreases, but if the number of pixels of the CCD for the green color separation optical image is set to 3360 in the lateral direction of the A4 size color original as in the present embodiment, the number of pixels in the blue image is blue. If it is less than about 1150 for green and about 750 for red, there is no visual effect on the output image.

According to an experiment conducted by the inventor, in a full-color image, even if the pixel density ratio is reduced to magenta: yellow≈1: 0.7, magenta: cyan≈1: 0.8, magenta: yellow: cyan = 1: 1: 1. The visual color sharpness was substantially the same as that of the image.

In order to effectively achieve the effect of the present invention, that is, to effectively reduce the light amount of the light source and the memory capacity, the ratio of the number of pixels of the CCD of each color is set to green: red: blue = 1: 0.8: 0.7
Is preferred. Therefore, there is no problem even if the ratio of the number of pixels such as CCD is reduced to the same ratio as above. That is, the number of pixels used by the solid-state image sensor for the green component: the number of pixels used by the solid-state image sensor for the blue component ≈ 1: 0.7, the number of pixels used by the solid-state image sensor for the green component: The number of pixels used by the solid-state image sensor for the red component ≒ 1: Red, blue, even if lowered to about 0.8
The ratio of the number of pixels of the solid-state image sensor for each color component of green is 1
The visual color definition is substantially the same as that of the image formed when

FIG. 8 is a main part of an optical system showing another embodiment of the multicolor image reading apparatus according to the present invention. In this case, compared with the embodiment shown in FIG. 4, the difference is that an ND filter for light amount correction is used. That is, in FIG. 8, 17 'and 18' are ND
It is for adjusting the light quantity of the light image separated into green light and red light by the color separation prisms 16 to 18 by the filter. When the same halogen lamp used for the original exposure scanning in the previous embodiment was scanned by applying 0.8 KW of power, the amount of red light that passed through the ND filter 17 ′ and reached the CCD 21 was exactly the same as the ND filter 18 When ‘is not as shown in FIG. 4, the ND filter 18 ′ is made equal to the amount of red light received by the CCD 21 when the halogen lamp is supplied with 0.55 KW of power and exposure scanning is performed.
The concentration of is adjusted. Also, a halogen lamp
When 0.8KW of power is applied for scanning, the green light quantity that has passed through the ND filter 17 'and reached the CCD 20 is just 0.6KW of halogen light when the ND filter 17' is not as shown in FIG. The density of the ND filter 17 'is adjusted so that it is equal to the light amount of the green light received by the CCD 20 when the light is given to the lamp and scanned for exposure. 16 'is a transparent glass plate for optical path correction, which does not reduce the amount of blue light.

In the case of the present embodiment, 0.8 KW of electric power is applied to the halogen lamp to expose and scan the original, and blue light, green light and red light are respectively passed through the glass plate 16 'and the ND filters 17' and 18 '. The CCDs 19, 20 and 21 that receive light are respectively halogen lamps.
This is the same as the case where the power of 0.8KW, 0.6KW, 0.55KW is applied and the light is received by each power when the A4 size document is exposed and scanned. Therefore, the document image is printed out by the exposure scan of the A4 size document. can do.

That is, the halogen lamp 0.8 KW is applied to the power source to expose and scan the original, and the light is received through the color separation optical system shown in FIG.
The CCDs 19, 20, and 21 are sequentially and repeatedly scanned in this order, and the respective image signals are successively stored in the image memories 37, 38, and 39 through the circuit shown in FIG. If this is printed out by the LBP 44 via the buffer memory 43, the image of the original document can be printed out in full color by only one exposure scanning of the original image.

In this case, if the glass plate 16 'and the ND filters 17' and 18 'shown by the one-dot chain line as shown in FIG. 5 are used at the positions shown in the figure, the multicolor image reading apparatus of this embodiment can be used as a laser. A block diagram of an electric circuit when applied to a beam printer is constructed. Since this operation is apparent from the above description and the description of the previous embodiment, the description is omitted.

Also in the case of the present embodiment, when the original is A4 size, CCD 19, 20, 2
The number of each pixel of 1 and the number of bytes of each of the image memories 37, 38 and 39 are the same as the numbers described in the embodiment shown in FIGS. 4 and 5, and the same effect as the previous embodiment is obtained. Is clear.

Although not described in each of the above embodiments, the CCDs 19, 20 and 21 are provided adjacent to each other in three rows as shown in FIG. 1 without using the color separation prism, and the color separation filters are provided on the CCDs 19, 20 and 21. Good. In this case, by adjusting the density of the color separation filter, it can also be used as the ND filter used in FIG. Of course, a red filter may be used instead of the ND filter.

In the experiment of each of the above examples, CCD19,20,2
The number of pixels made by Toshiba is 1 and the number of pixels of CCD 19 is 1,728.
As the CCD, a CCD having 2592 elements was used as the CCD20, and a CCD having 2048 elements was used as the CCD21. Of course, the fourth
Using the optical system shown in FIG. 8 and FIG. 8, the first CCD chip group arranged on one side of the optical system has an image forming lens 8 or the like for an image located in the middle or more from the end of the A4 size document. The second CCD chip group, which is arranged so as to form an image through the first CCD chip group, is arranged at the end of the first CCD chip group, corresponding to the position where the image is formed at the end of the first CCD chip group. It is arranged so as to form an image from the position of the original to the other end of the original via the imaging lens 8 and the like.

Therefore, when scanning these chip groups, it is sufficient to scan from the CCD of the first chip group to the image forming position of the original image of the CCD of the second chip group. For example, the CCD20 needs to have 3360 elements, so if a 2-chip CCD is used, 2592 × 2 = 5184
Although there is the number of elements, actually, the CCD 20 part in the second chip group having the number of elements of 5184-3360 = 1824 is not used.

The reading optical system shown in FIG. 9 has three equal-magnification image sensors using an amorphous film such as CdS-CdSe, Se-As-Te, and Si instead of the reduction type CCD shown in FIG. 1 or 4. 56,5
7,58 are aligned such that the longitudinal direction thereof is perpendicular to the sub-scanning direction (arrow direction). A color document 2 on a platen glass 1 is illuminated by a halogen lamp 3 and the reflected light thereof has blue, green and red color separation filters 50, 51 and 52, for example, an array of focusing rod lenses known under the trade name of Self-Ok. A small-diameter image-forming element array 53, 54, 55 (all of which are aligned in the direction perpendicular to the arrow to the length of the width of the platen glass 1 and are arranged in the same-size image sensors 56, 57, 58, respectively). 1: 1 type image sensor 56,5 via
Images are formed on 7,58 respectively.

In the case of the unit size image sensor shown in FIG. 9, since the amorphous semiconductor itself has a high internal resistance,
Therefore, it is not necessary to disperse each pixel, and the number and width of the readout electrodes may be adjusted. That is, when reading a color original, the number and width of each readout electrode of the same-size image sensors 56, 57, and 58 are set to the sensitivity of each image sensor in the wavelength region of each color and the specific energy of a light source such as a halogen lamp and each color. The selection should be made according to the visual color definition. Of course, the light-receiving areas and lengths of the same-size image sensors 56, 57, 58 at this time are constant. In the sub scanning, the platen glass 1 may be moved together with the color original 2, or conversely, the halogen lamp 3 as the light source and the small-diameter image forming element array 5 may be moved.
3, 54, 55 (including the color separation filters 50, 51, 52) and the same-size image sensors 56, 57, 58 may be integrally moved in the direction of the arrow shown. Also in this case, the electric power of the halogen lamp 3 as the light source is adjusted for each color and scanning is performed three times.
The signal processing is self-evident from the previous embodiment and is omitted here for the sake of simplicity.

In the above-described embodiment, the image data is printed out by processing the image data obtained by performing color separation by exposing and scanning the color original document three times. However, the area of each pixel of the image sensor for each color and It goes without saying that the image signals for the three primary colors may be taken out from the image sensor by only one exposure scan of the color original by the light source using the same electric power by adjusting the pixel density.

In addition to the above, the present invention can be applied to a reading device having no image memory, and needless to say, it is not necessary to use a color hard copy as an output, and it is needless to say that a soft copy device such as a cathode ray tube can also be applied.

As described above, according to the present invention, it is effective in reducing the size of the power consumption reducing device and reducing the temperature rise of the platen, and is also effective in reducing the storage capacity when the color separation image information is stored. The visual definition of the color image formed thereby does not change.

Further, by individually providing the driving means for each solid-state image sensor provided for each color, it is possible to make the reading time in each solid-state image sensor the same and to simplify the control system for the reading operation of the multicolor original document. be able to.

[Brief description of drawings]

1 and 2 are explanatory views of a conventional digital copying apparatus,
FIG. 3 is a diagram showing the spectral sensitivity characteristics of a CCD and the output wavelength characteristics of a halogen lamp, FIG. 4 is a partial view of an optical system of a multicolor image reading device according to the present invention, and FIG. 5 is a multicolor image according to the present invention. A block diagram of an electric circuit when the image reading device is applied to a laser beam printer, FIG. 6 is a diagram showing a time chart of FIG. 5, FIG. 7 is a diagram showing input / output characteristics of a semiconductor laser, and FIG. FIG. 9 is a partial view of an optical system of a multicolor image reading device to show another embodiment, and FIG. 9 is an explanatory view showing another embodiment of the multicolor image reading device according to the present invention. 2 …… Color original 3 …… Halogen lamp 7 …… Near infrared cut Visible light transmission filter 8 …… Imaging lens 16,17,18 …… Color separation prism 17 ′, 18 ′ …… ND filter 19,20, 21 …… CCD 22,23,24 …… CCD drive circuit 37,38,39 …… Image memory 44 …… Laser beam printer 47 …… Sequence controller 50,51,52 …… Color separation filter 53,54,55… … Small-diameter imaging element array 56,57,58 …… Same size image sensor (of amorphous film)

Claims (1)

[Claims] 1. A multicolor image reading apparatus having three solid-state image sensors provided corresponding to each color of blue, red, and green for reading color-separated image light from a multicolor original, wherein the three solid The light receiving area of the image sensor is substantially the same, and the number of pixels of the solid-state image sensor corresponding to blue is X,
When the number of pixels of the solid-state image sensor corresponding to red is Y and the number of pixels of the solid-state image sensor corresponding to green is Z,
A multicolor image reading apparatus having a function of X <Y <Z, wherein driving means for driving the solid-state image sensor is separately provided for each of the three solid-state image sensors.