JP2003008911A - Image reading apparatus, its control method, controller, program, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration of read-image quantity caused by LED color-tone variations in the case that a white-color LED illumination module is used as a light source of a color-image reading apparatus. SOLUTION: The color-image reading apparatus includes an illumination module formed of a plurality of white-color LEDs arranged in a main-scanning direction; an image sensor such as a CCD; a unit for moving the original and the image sensor relatively in a sub-scanning direction; and an input masking unit. The illumination module is formed of LEDs having the same color-tone rank. The color-image reading apparatus also includes a setting unit for setting a color-tone rank for the illumination module, and a control unit such as a CPU, for switching a parameter of the input masking unit according to the color-tone rank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device, and more particularly to an image reading device having a plurality of light sources having different color tones.

[0002]

2. Description of the Related Art White light as a light source in an image reading apparatus is realized by adding a plurality of lights. Specifically, among a plurality of LEDs, a blue or ultraviolet electromagnetic wave (hereinafter, referred to as light) from a predetermined LED light source is converted to light of other wavelengths such as yellow by passing through a phosphor, and the like. White light has been realized by adding the light of. Here, since the luminous efficiency of the phosphor varies depending on the wavelength of the light source, if the wavelength of the light source is subtly different, the amount of light emitted by the phosphor changes accordingly. It also changes depending on the amount of phosphor. For this reason, the color tone varies depending on the white LEDs. The term "color tone" as used herein refers to color mixture, tone such as shades and strengths, and shade. Specifically, pure white, yellowish white, bluish white, and the like. This difference cannot be ignored because it can be visually recognized.

[0003]

Therefore, when the image is read without considering the color tone variation of the light source, the color tone variation occurs, and the color tone variation also occurs in each light source module as the illumination means. The quality deteriorates.

[0004]

SUMMARY OF THE INVENTION In the present invention, the above-mentioned problems are taken into consideration.
An irradiation means in which a plurality of light sources for irradiating a subject image are arranged,
The first image of the subject illuminated by the illumination means is read.
Photoelectric conversion means for outputting the signal, rank setting means for setting the color tone rank of the plurality of light sources, signal correction means for correcting the first signal output by the photoelectric conversion means, and And a control means for calculating the first data and controlling the correction by the signal correction means based on the first data.

Further, in the image reading apparatus according to a second aspect of the present invention, in addition to the first aspect, the rank is divided for each area occupying a predetermined area on the XYZ colorimetric chromaticity diagram. It is divided into.

Further, in the image reading apparatus described in claim 3, in addition to the description in either claim 1 or 2, the signal correction means performs matrix calculation.

The image reading apparatus according to a fourth aspect is the image reading apparatus according to any one of the first to third aspects, wherein the irradiation means are arranged in an array in the main scanning direction.

According to a fifth aspect of the present invention, in addition to any one of the first to fourth aspects, the light irradiation means is composed of a plurality of light sources having the same rank.

In the image reading device according to the sixth aspect, the light source has a fluorescent material.

A control method according to a seventh aspect of the present invention is a control method of an image reading apparatus having an irradiation means in which a plurality of light sources for irradiating a subject image are arranged, and the color tone ranks of the plurality of light sources are set. And rank setting step,
The first image of the subject illuminated by the illumination means is read.
And a signal output step, and a control step of calculating first data according to the rank and controlling the output first signal to be corrected based on the first data. .

Further, in a control method according to an eighth aspect, in addition to the seventh aspect, the rank is divided into regions occupying a predetermined area on the XYZ colorimetric system chromaticity diagram. It is divided.

The control method according to a ninth aspect is the control method according to any one of the seventh to eighth aspects, wherein the first data includes a matrix coefficient.

Further, in a control method according to a tenth aspect of the present invention, the irradiation means are arranged in an array in the main scanning direction, in addition to the above-mentioned seventh aspect.

In the control method according to the eleventh aspect, the light irradiating means is composed of a plurality of light sources having the same rank.

The program according to claim 12 is
It is a program executable by an information processing apparatus having a program code for implementing the image processing method according to any one of claims 7 to 11.

A storage medium according to a thirteenth aspect is a storage medium storing the program according to the twelfth aspect.

An image reading apparatus according to a fourteenth aspect of the present invention is to output a signal for reading a subject image illuminated by the illuminating unit and a illuminating unit in which a plurality of light sources for illuminating the subject image are arranged in a first direction. And a control means for controlling so as to correct the second signal output from the photoelectric conversion means based on the first data, and the first data is transmitted from the photoelectric conversion means. First output
Is data calculated from the signal and the information about the first direction.

Further, in the image reading apparatus according to a fifteenth aspect, in addition to the statement of the fourteenth aspect, the first data is
The calculation is performed on each of the plurality of light sources arranged in the first direction.

Further, in the image reading apparatus according to a sixteenth aspect, in addition to the one according to any one of the fourteenth to fifteenth aspects, the irradiation means includes a plurality of groups each including a plurality of light sources in the first direction. While having, the first data is calculated for each of the plurality of groups.

According to an image reading apparatus described in claim 17, in addition to the structure described in any one of claims 14 to 16, the first data includes a matrix coefficient.

A control method according to a eighteenth aspect is a control method for an image reading apparatus having an irradiation means in which a plurality of light sources for irradiating a subject image are arranged in a first direction.
A signal output step of reading a subject image irradiated by the irradiation means and outputting a signal; and a control step of controlling so as to correct the second signal output from the photoelectric conversion means based on the first data. However, the first data is data calculated from the first signal output from the photoelectric conversion means and the information regarding the first direction.

Further, in the control method according to claim 19, in addition to the description of claim 18, the first data is the first data.
Is calculated for each of the plurality of light sources arranged in the direction.

Further, in a control method according to a twentieth aspect, in addition to any one of the eighteenth to nineteenth aspects, the irradiation means has a plurality of groups each including a plurality of light sources in the first direction. At the same time, the first data is calculated for each of the plurality of groups.

The control method according to a twenty-first aspect of the present invention is the method according to any one of the eighteenth to twentieth aspects, wherein the first data includes a matrix coefficient.

Further, the program according to claim 22 is
A program executable by an information processing device having a program code for realizing the image processing method according to claim 18.

A storage medium according to a twenty-third aspect is a storage medium storing the program according to the eighteenth aspect.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, the entire color copying machine as an image forming apparatus as an image reading apparatus used in the present embodiment will be described.

FIG. 1 is a diagram showing a sectional structure of an image forming apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 201 is an image scanner unit, which reads a document and performs digital signal processing. A printer unit 200 prints out an image corresponding to the original image read by the image scanner unit 201 on paper in full color.

In the image scanner section 201, the original 204 placed on the original platen glass (platen) 203 by the original pressing plate 202 is irradiated with the light of the LED module 205. The reflected light from the original 204 is reflected by the mirror 20.
The image is formed on a three-line sensor (hereinafter referred to as CCD) 210 by a lens 208. In addition,
The lens 208 is provided with an infrared cut filter 281.

The CCD 210 color-separates the light information from the original 204, reads the red (R), green (G), and blue (B) components of the full-color information, and sends it to the signal processor 209. . Each color component reading resensor array of the CCD 210 is composed of 5000 pixels. As a result, 297 mm in the lateral direction of the A3 size document, which is the largest size of the documents placed on the platen glass 203, is read at a resolution of 400 dpi.

The white LED array 205 and the mirror 2
06 is a velocity V, and the mirror 207 is a velocity of (1/2) V, and is perpendicular to the electrical scanning direction of the line sensor 210 (hereinafter referred to as the main scanning direction) (hereinafter referred to as the sub-scanning direction). ) Mechanically moves the document 204
Scan the entire surface of. The required light sources are firstly high luminous efficiency and low power consumption, secondly, the amount of light emission can be changed depending on the position in the main scanning direction, thirdly, white light source, and these three conditions. As an existing light source, a white LED array can be considered. That is, a plurality of white LEs
D is arranged in the main scanning direction to illuminate the entire main scanning area. At this time, in order to make the end portion brighter than the central portion, for example, the density of the light emitting elements is made denser in the peripheral portion than in the central portion. The peripheral portion is made larger than the central value of the current flowing through the light emitting element. The PWM control increases the duty in the peripheral area compared to the central area. Such a method can be considered.

The reason why the LED is used as the light source in this embodiment is as follows.

A halogen lamp, a fluorescent lamp, a xenon lamp or the like may be used as a reading light source for a copying machine, a fax machine or the like which uses a CCD linear image sensor for reading.

A reduction optical system is assembled with a lens, for example, A4
A document with a longitudinal main scanning of 297 mm is measured by a lens with a pixel size of 10 microns, a CCD of 5000 elements, that is, 50
The image is formed on the CCD surface of mm length. Here, due to the characteristics of the lens such as the cosine fourth law, there is a characteristic that the central portion of the main scanning is bright and has a large amount of light and the end portion of the main scanning is dark and has a small amount of light. This is directly C
The output signal of the CD deteriorates the S / N of the signal at the main scanning end.

In the case of a halogen lamp, the number and position of filaments that emit light and the number of filament windings can be made relatively freely. Therefore, the number of windings of the filament is increased so that the filament emits brighter light as it approaches the end, and the above-mentioned problem is addressed.

From the viewpoint of power consumption, fluorescent lamps and xenon lamps are more advantageous than halogen lamps. Fluorescent lamps and xenon lamps have relatively high luminous efficiency and can be said to be desirable light sources from the viewpoint of environmental consideration. However, the amount of light emission cannot be changed depending on the position in the main scanning direction by adjusting the number of filament windings as in the case of a halogen lamp.

When color reading is performed by an image reading device in a copying machine, a color 3-line CCD image sensor may be used as a reading element. For example, three photodiode element rows are formed in parallel at intervals of four times the main scanning pixel pitch, and RGB color filters are formed in each element row.

In this case, the light source for illuminating the original is set to have a wavelength.
It is essential that the light source is a so-called white light source that contains light with multiple wavelengths of 400 to 700 nm.

Here, the advantage of using the white LED, in which the luminous efficiency and the luminous brightness are remarkably improved, becomes clear.

The standard white plate 211 is a white plate as a reference member for correcting non-uniformity of image reading by the 3-line sensor 210 and the lens 208 as the photoelectric conversion means. By reading the image of the standard white plate 211 illuminated by the LED module 205, R, G, B
The correction data of the read data of the sensors 2101, 1022, 2103 is generated. This standard white plate 211 is
It shows almost uniform reflection characteristics in visible light, and has a white color in the visible. Here, the standard white plate 211 is used to correct the output data from the R, G, B sensors 2101, 1022, 2103.

In the signal processing unit 209, the read signal is electrically processed and decomposed into magenta (M), cyan (C), yellow (Y), and black (Bk) components, which are then processed. To the printer unit 200. Further, the image scanner unit 201 scans the document once.
For M, C, Y, Bk, one component is the printer unit 2
Then, the printout for one sheet is completed by scanning the original document four times in total.

In the printer section 200, the M, C, Y and Bk image signals from the image scanner section 201 are sent to the laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the image signal. Then, the laser light scans the photosensitive drum 217 via the polygon mirror 214, the f-θ lens 215, and the mirror 216.

The developing device is composed of a magenta developing device 219, a cyan developing device 220, a yellow developing device 221, and a black developing device 222. These four developing devices are alternately in contact with the photosensitive drum 217, and are placed on the photosensitive drum 217. The formed M, C, Y and Bk electrostatic latent images are developed with corresponding toners. In addition, the transfer drum 223 is connected to the paper cassette 22.
4 or the paper fed from the paper cassette 225 is wound around the transfer drum 223, and the toner image developed on the photosensitive drum 217 is transferred onto the paper.

In this way, the toner images for the four colors M, C, Y, and Bk are sequentially transferred, and then the sheet passes through the fixing unit 226 and is ejected.

Next, the image scanner unit 201 according to this embodiment will be described in detail.

FIG. 2 is a diagram showing the external structure of the CCD 210.

In FIG. 2, reference numeral 2101 denotes a light receiving element array (photosensor) for reading red light (R).
102 and 2103 are, in order, green light (G) and blue light (B).
It is a light receiving element array for reading the wavelength component of.

These R, G, B sensors 2101, 21
02 and 2103 are 10 μm in the main scanning direction and the sub-scanning direction.
With an opening of.

The above three light receiving element arrays having different optical characteristics have the following monolithic structure on the same silicon chip. That is, the R, G, and B sensors are arranged in parallel with each other so as to read the same line of the document.

By using the CCD 210 having such a configuration, the optical system such as the lens 208 is common in each color separation reading. This makes it possible to simplify the optical adjustment for each color of R, G, and B.

FIG. 3 is a sectional view of the photo sensor.

As shown in FIG. 3, a silicon substrate 2105
A photo sensor 2101 for reading the R color and photo sensors 2102, 210 for reading the visible information of G and B respectively.
3 are arranged.

On the R-color photo sensor 2101, an R filter 2107 that transmits the R-color wavelength component of visible light is arranged. Similarly, a G filter 2108 is provided on the G color photo sensor 2102, and a B color photo sensor 21 is also provided.
A B filter 2109 is arranged on 03. 2106 is a flattening layer made of a transparent organic film.

FIG. 4 is an enlarged view of the photosensors 2101, 1022 and 2103 indicated by the symbol B in FIG.

As shown in FIG. 4, each sensor has a length of 10 μm per pixel in the main scanning direction. Each sensor has 5000 pixels in the main scanning direction. As described above, this is in the lateral direction of an A3 size document (length 297 m).
This is so that m) can be read at a resolution of 400 dpi. The distance between the lines of the R, G and B sensors is 80 μm. Therefore, 400 dpi
8 lines apart from each other in the sub-scanning direction.

Next, a density reproduction method in the printer section of the image processing apparatus according to this embodiment will be described.

In this embodiment, in order to reproduce the density of the printer, the lighting time of the semiconductor laser 213 is controlled according to the image density signal by the PWM (Pulse Width Modulation) method. As a result, an electrostatic latent image having a potential according to the laser lighting time is formed on the photosensitive drum 217. Then, the developing devices 219 to 222 develop the latent image with toner in an amount corresponding to the potential of the electrostatic latent image, thereby reproducing the density.

FIG. 5 is a timing chart showing the control operation of density reproduction in the printer section according to the present embodiment.

The signal 10201 is the printer pixel clock. This corresponds to a resolution of 400 dpi. In addition,
This clock is generated by the laser driver 212. Also, in synchronization with the printer pixel clock 10201, 40
A 0-line triangular wave 10202 is created. In addition, this 400
The period of the line triangular wave 10202 is the pixel clock 1020.
It is the same as the cycle of 1.

256 gradations (8B) at a resolution of 400 dpi
it) M, C, Y, Bk image data, and 200/40
The 0-line switching signal is transmitted from the image signal processing unit 209 in synchronization with the printer pixel clock signal 10201. This is a laser driver 212, which is a FIFO (not shown).
The memory synchronizes with the printer pixel clock 10201. This 8-bit digital image data is converted into an analog image signal 10203 by a D / A converter (not shown). Then, it is compared with the above-mentioned 400-line triangular wave 10202 in an analog manner, and as a result, 40
A 0 line PWM output 10204 is generated.

8-bit digital pixel data is 00H
(H shows hexadecimal number) to FFH, 400
The line PWM output 10204 has a pulse width corresponding to these values. Further, one cycle of 400-line PWM output is 63.5 μm on the photosensitive drum.

In addition to the 400-line triangular wave, the laser driver 212 also produces a 200-line triangular wave 10205 having a period twice that in synchronization with the printer pixel clock 10201. And this 200-line triangular wave 10205 and 4
A PWM output signal 10206 of 200 lines is generated by comparing the analog image signal 10203 of 00 dpi. The PWM output signal 10206 of the 200 line is shown in FIG.
As shown in, a latent image is formed on the photosensitive drum at a period of 127 μm.

In the density reproduction with 200 lines and the density reproduction with 400 lines, the gradation of 200 lines is better reproduced. This is because the minimum unit for density reproduction is 127 μm, which is twice the 400 lines. However, in terms of resolution, 6
400 lines that reproduce the density in units of 3.5 μm are more suitable for high-resolution image recording. As described above, the 200-line PWM recording is excellent in gradation reproduction, while the 400-line PWM recording is excellent in resolution. Therefore, the PWM of 200 lines and the PWM of 400 lines are switched depending on the nature of the image.

The signal for performing the above switching is the 200-line / 400-line switching signal 10207 shown in FIG. The signal is input from the image signal processing unit 209 to the laser driver 212 in pixel units in synchronization with the 400 dpi image signal. This 200 line / 400 line switching signal is logical Lo
In case of w (hereinafter referred to as L level), PW of 400 lines
M output is selected. On the other hand, in the case of logic High (hereinafter referred to as H level), the PWM output of 200 lines is selected.

Next, the image signal processing unit 209 will be described.

FIG. 6 is a block diagram showing the flow of image signals in the image signal processing unit 209 of the image scanner unit 201 according to this embodiment.

As shown in FIG. 6, the image signal output from the CCD 210 is input to the analog signal processing circuit 101. Therefore, gain adjustment and offset adjustment are performed.
Then, the A / D converter 102 outputs 8 for each color signal.
Bit digital image signals R1, G1, and B1 are converted. Then, it is input to the shading correction unit 103. Therefore, known shading correction using the read signal of the standard white plate 211 is performed for each color.

The clock generator 121 generates a clock for each pixel. In addition, the main scanning address counter 12
In 2, the clock from the clock generator 121 is counted to generate a pixel address output for one line. And
The decoder 123 decodes the main scanning address from the main scanning address counter 122. As a result, a CCD drive signal for each line such as a shift pulse and a reset pulse, a VE signal representing an effective area in a one-line reading signal from the CCD, and a line synchronization signal HSYNC * are generated. The main scanning address counter 122 is HSYNC.
It is cleared by the * signal and counting of the main scan address of the next line starts.

As shown in FIG. 2, the light receiving sections 2101, 1022, and 2103 of the CCD 210 correct the spatial shift in the sub-scanning direction in the line delay circuits 104 and 105 of FIG. This is because the light receiving units 2101, 1022, 210 are arranged at a predetermined distance from each other. Specifically, the R and G signals are line-delayed in the sub-scanning direction with respect to the B signal, and are aligned with the B signal.

The input masking section 106 is a CCD 210.
Is a part that converts the read color space determined by the spectral characteristics of the R, G, and B filters 2107, 2108, and 2109 into the NTSC standard color space. This performs a matrix operation like the following formula.

[0072]

[Outer 1]

Light amount / density converter (LOG converter) 10
Reference numeral 7 comprises a look-up table ROM. As a result, the R4, G4, and B4 luminance signals are converted into CO, MO, and YO concentration signals. The line delay memory 108 is a UCR, F generated from R4, G4, B4 signals in a black character determination unit 113 described later.
The image signals of CO, MO, and YO are delayed by the line delay until the judgment signal of ILTER, SEN, etc.

As a result, the C1, M1, and Y1 image signals and the black character determination signal for the same pixel are masked by the UCR circuit 109.
Are entered at the same time.

The masking and UCR circuit 109 extracts the black signal (Bk) from the input three primary color signals of Y1, M1, and C1. Further, the masking and UCR circuit 109 performs an operation for correcting the color turbidity of the recording color material in the printer 212, and sequentially outputs Y2, M2, C2, and Bk2 signals at a predetermined bit width ( 8 bit).

The main scanning magnification changing circuit 110 performs enlargement / reduction processing of the image signal and the black character determination signal in the main scanning direction by a known interpolation calculation. In addition, the spatial filter processing unit (output filter) 111, as described later, based on the 2-bit FILTER signal from the LUT 117, edge enhancement,
Switches smoothing processing.

The frame-sequential image signals of M4, C4, Y4 and Bk4 thus processed and the SEN signal which is a switching signal of 200 lines / 400 lines are sent to the laser driver 212. Then, the printer unit 200 performs density recording by PWM.

FIG. 7 shows the image signal processing unit 209 shown in FIG.
3 is a diagram showing the timing of each control signal in FIG.

In FIG. 7, the VSYNC signal is an image effective segment signal in the sub-scanning direction. As a result, image reading (scanning) is performed in the logical "1" section, and the output signals of (C), (M), (Y), and (Bk) are sequentially formed. Further, the VE signal is an image effective section signal in the main scanning direction. As a result, the timing of the main scanning start position is set in the logical "1" section. This is mainly used for line delay line counting control. And CLOC
The K signal is a pixel synchronization signal. As a result, "0" →
At the rising edge of "1", the image data is transferred at the retiming,
The signal is supplied to each signal processing unit of the A / D converter 102 and the black character determination unit 113. At the same time, the CLOCK signal is sent to the laser driver 212 as an image signal, 200 lines / 40
It is used to transmit the 0 line switching signal.

Next, the characteristics of the lens will be described.

When illumination with a uniform amount of emitted light is prepared at each position in the main scanning direction and is imaged on a CCD line image sensor, the distribution of illuminance on the CCD surface is bright in the central part and at the edges. The part gets dark. This property is known as the cosine fourth law. This measure is taken as follows.

A white LED is used and constructed as follows. The white LED realizes white light as follows. That is, blue or ultraviolet light emitted from the LED is applied to the phosphor to convert the wavelength. Then, by adding other lights, light having a wavelength in the visible light region including wavelengths of 400 nm to 700 nm is emitted.

FIG. 8 is a view for explaining the light amount distribution on the CCD image plane.

As described above, by taking measures against the cosine fourth law of the lens, the amount of light emission is made larger at the end portion compared to the center in the main scanning direction, so that the incident light amount distribution on the CCD image plane is flat. It is a figure explaining that it has become.

In the present embodiment, as will be described later, the PWM control is used in order to make the light quantity at the end portion larger than that at the central portion. The amount of electric power supplied to the LEDs may be increased by increasing the amount of current supplied to the LEDs.

The fluorescent lamp is also PWM-controlled, but its control cycle is about 300 μS, which is about the same as the scanning cycle of the main scanning. Here, the white LED can be controlled more finely than the fluorescent lamp. This is because it is a semiconductor element and high-speed on / off control is possible in the order of 10 nS or higher.

Next, FIG. 9 described above is a block diagram of the image scanner unit 201 of the present embodiment. Reference numeral 801 corresponds to an operation panel of an image forming apparatus or the like, or an operation screen of a personal computer or the like. The controller 802 that controls each function of the present apparatus controls the start-up, stop, and operation mode setting of the apparatus by communication with the operation panel 801 and the personal computer 228. PWM
The control circuit 1031 is a white LED as a light source described later.
ON / OFF of the entire array 205 is controlled. Also, LE
It also controls the light amount adjustment when D is on. Motor control unit 80
Reference numeral 7 controls the driving of the mirror base unit including the white LED array 205 in the sub-scanning direction. Signal processing unit 209
Is as described above.

FIG. 10 is a schematic diagram for explaining the structure of the white LED array 205.

The white LED arrays 205 are LE
The LED module is divided into D modules and each LED module is lit and controlled by a PWM control circuit 1031.

FIG. 11 is a diagram for explaining the hardware configuration of the above LED array 205.

The plurality of LEDs are connected to each other via a current limiting resistor.
It is connected to the PWM control circuit 1031. In the PWM control circuit 1031, the duty of each LED is set by control means such as a controller 802 (not shown).

By adopting such a hardware configuration, an arbitrary light distribution can be obtained. By using this configuration, in the present embodiment, the amount of light is increased at the end portion compared to the central portion.

FIG. 12 is a diagram for explaining the manner of light distribution control by PWM control.

In this embodiment, the PWM control cycle is set to 10
As μS, the luminance is increased at the end portion where a large amount of light is required, and therefore the duty ratio of the current supplied to the end portion is increased. On the other hand, the brightness is reduced in the central portion where the light amount may be relatively small. Therefore, the duty ratio supplied to the central part is small.

Relative control is sufficient for this control. That is, the light amount may be controlled so that the end portion has a relatively large light amount with respect to the central portion. Alternatively, the light amount may be controlled so that the end portion has a smaller amount of light than the central portion.

FIG. 13 is a white LE according to this embodiment.
It is a structural diagram of D.

The light source LED 105 emits blue or ultraviolet light.
The light is emitted at 1, and the phosphor 1052 converts the light into light having another wavelength such as yellow. White light is emitted by adding light of multiple wavelengths.

FIG. 14 is a white LE according to the present embodiment.
It is a figure which shows the spectral characteristic of D.

On the short wavelength side, the blue peak is the light source LED 105.
1, and the broad green to red part on the right side is the light converted from blue by the phosphor 1052.

The luminous efficiency of the phosphor varies with the amount of light emitted by the phosphor. This is because the light source wavelength is slightly different because it varies depending on the wavelength of the light before conversion by the phosphor. Therefore, the color tone varies depending on the white LEDs. Specifically, pure white,
Yellowish white, bluish white, etc. As described above, this difference cannot be ignored because it can be visually recognized.

Therefore, as described below, LEDs (even white LEDs of the same type) are divided into several stages for each color tone rank.

FIG. 15 shows CIE (XYZ system chromaticity coordinates).

In this figure, three ranks a,
It is divided into b and c. Here, the above-mentioned variation in color tone does not vary at all at random, and when a straight line rising to the right is drawn on the XYZ system chromaticity coordinates, it is dispersed in such a manner that it is approximately on it.

However, when a color image is read without considering the color tone variation of the white LED at all, the color tone variation occurs in the main scanning direction. Also,
Since color tone variations also occur for each LED lighting module, there arises a problem that the color reading quality deteriorates.

In the embodiment of the present invention, such a problem is solved by the following configuration.

The LED light source module 205 is LE
D of the same color tone rank is used. In the present embodiment, the chromaticity XYZ values are measured with a colorimeter and X
The LEDs are ranked according to the YZ system chromaticity coordinates 104. Here, in this embodiment, it is divided into three ranks. It should be noted that higher accuracy can be dealt with by increasing the number of ranks.

<Formation of Light Source Module Only with LEDs of the Same Rank> Here, for example, it is assumed that the light source module is formed by using the LEDs of the same rank, which are divided into ranks as described above.

The advantage of forming one light source module with only LEDs of the same rank is to suppress variations in the color tone of the read image. For more details,
When reading in a state where LEDs of various color tones are separately arranged in the main scanning direction, it is possible to avoid the problem that the color tone of the image read in the main scanning direction is considerably different. That is, since the light source module is created only by LEDs of the same rank, it is possible to avoid variations in color tone in the main scanning direction.

In this case, when a plurality of light source modules constituting the white LED 205 are compared with each other, the color tones are different among the modules, so that the white LED array 205 varies in color tone as a whole. As described above, there is a choice not to use LEDs of other color tone ranks, but this would result in poor yield and high cost.

<Changing Parameters of Color Computation Means According to Rank> Therefore, in the present embodiment, LEDs of various color tone ranks are used, and the configuration is as follows.

It has means for setting the color tone rank of the white LED light source module to be used, and control means for switching the parameters of the matrix color computing means according to the color tone rank.

FIG. 16 is a flow chart for explaining the rank division in this embodiment. The following processing is the operation under the control of the controller 802.

First, the color tone rank signal from the operation panel 801 or the like is received as the color tone rank of the light source module to be used (step S101). In this embodiment, the setting is made by the operator, but the light source module is provided with rank information magnetically, electrically, and optically,
By having a means for automatically setting at the time of setting, it is possible to avoid the operator's complicated work.

Next, based on this color tone rank setting information, the difference is removed by the color calculating means. First, the corresponding coefficient of the input masking unit 106 is selected based on the received color tone rank setting information (step S10).
2). The selected coefficient is switched as the input masking coefficient (step s103). In the present embodiment, the coefficient of the input masking unit 106 is switched to an appropriate coefficient corresponding to the rank classification according to each. Using the masking coefficient, the above-described arithmetic processing is performed (step S104).

In this embodiment, regardless of the color tone rank of the LED light source module, NTSC (National
A 3 × 3 masking coefficient is designed so that it can be converted into the standard color space of the Television Standards Committee. The matrix calculation as shown in the following equation is performed.

[0116]

[Outside 2]

In the present embodiment, the matrix operation is performed up to the primary term of 3 × 3, but if the order is increased and, for example, the matrix including the secondary term is used, the accuracy is further improved.

It is better to use the direct mapping of the color space by the three-dimensional lookup table.

Here, the reason why RGB is output in the NTSC color space is that the input format of the RGB-CMYK conversion means to the printer in this embodiment assumes a color space corresponding to NTSC.

According to the present embodiment as described above, when the white LED illumination module is used as the light source of the color image reading device, the quality deterioration of the read image due to the color tone variation of the LEDs is suppressed. Also, L of the same color tone rank
By using the ED, color tone variation in the main scanning direction in the same module can be suppressed. Further, even when using LED lighting modules having a plurality of color tone ranks, by setting the color tone ranks, the difference can be absorbed by the color calculating means, and the same color tone can be obtained in any one of the plurality of lighting modules. The image can be read.

<Changing Masking Coefficient According to Main Scan Position> Even when white LEDs of the same rank are used, slight white level color tone variation occurs when the rank classification standard is loosened due to the yield. There are cases. Even in that case, better color reading can be performed by adopting the following configuration.

Further, even when white LEDs of different ranks are mixed, it is possible to aim at the effect of suppressing the quality deterioration due to the color tone variation of the LEDs. In this case, it is possible to avoid costing because it is possible to reduce the cost.

FIG. 17 is a diagram for explaining a configuration in which the masking coefficient can be changed depending on the main scanning position.

By using the target white LED array 205 in advance, the controlled standard white plate 211 is read to measure the color change depending on the main scanning position. Thus, the change in the color tone characteristic of the light source depending on the position in the main scanning direction can be measured in pixel units. An appropriate masking coefficient for each pixel corresponding to the main scanning position is obtained with respect to the thus-obtained color tone change for each pixel depending on the main scanning position of the light source.

Next, the above-obtained masking coefficient is given as unique data of the white LED array 205 to the image reading apparatus equipped with this white LED array 205. That is, the masking coefficient according to the main scanning position in the given one line described above is stored in the masking coefficient storage unit 1063 in FIG.

The main scanning position discriminating unit 1064 receives the main scanning synchronizing signal HSYNC and the pixel clock CLK,
At the time of image reading, information including main scanning position information indicating which main scanning position information is currently processed is output.

Loading unit 106 for selecting masking coefficient
In 2, the masking coefficient for each pixel corresponding to the main scanning position currently processed is read from the masking coefficient storage unit 1063 according to the main scanning position information, and is input to the masking calculation unit 1061. The masking calculation unit performs the above-described 3 × 3 matrix calculation in pixel units.

Here, in the above description, the configuration in which the masking coefficient is calculated in pixel units has been described. On the other hand, the masking coefficient according to the main scanning position need not be prepared for all pixels, as described in <Changing Parameters of Color Calculation Means Depending on Rank>. That is, for example, in FIG.
It is also effective to store only the values of the six representative points at the main scanning position in units of the LED module described in the above. This means that it is possible to adopt a method of interpolating the representative points and the points between the representative points by calculation by a masking coefficient calculating unit (not shown). In this case, LE
The configuration can be simplified by performing a considerable rank division in units of D modules and reading the standard white plate 211 so as to obtain the masking coefficient corresponding to each of the LED modules.

With the above-described construction procedure of this embodiment, the white LE
Even when the color tones of the white LED chips mounted on the D array 205 do not completely match, an image can be read with precise color quality. Further, by performing the process of changing the masking coefficient according to the main scanning position, there is an effect that image quality deterioration due to color tone variation of the LED light source can be suitably suppressed.

<Other Embodiments> Although the external PC 809 is connected to the external PC 809 by SCSI in the first to third embodiments, the present invention is not limited to this, and other known standards can be used. Needless to say, the one used may be used.

Further, even when the present invention is applied to a system composed of a plurality of devices (eg, host computer, interface device, scanner, etc.), a device composed of one device (eg, copying machine, facsimile device, etc.) May be applied to.

Further, an object of the present invention is to supply a storage medium (or recording medium) recording a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer of the system or apparatus ( Alternatively, by the CPU or MPU) reading and executing the program code stored in the storage medium,
It goes without saying that it will be achieved. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also based on the instruction of the program code,
An operating system (OS) running on the computer does some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized. Here, as the storage medium for storing the program code, for example, a floppy (registered trademark) disk, a hard disk, a ROM,
RAM, magnetic tape, non-volatile memory card, CD-
ROM, CD-R, DVD, optical disk, magneto-optical disk, MO, etc. are considered.

Further, after the program code read out from the storage medium is written in the function expansion card inserted in the computer or the function expansion unit connected to the computer, the instruction of the program code is given. Based on the above, the CPU provided in the function expansion card or function expansion unit performs a part or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized.

When the present invention is applied to the above storage medium, the storage medium stores the program code corresponding to the flowchart shown in FIG. 16 described above.

[0135]

As described above, according to the preferred embodiment of the present invention, it is possible to reduce the deterioration of the reading quality even when an image is read in which the color tone variation occurs in the illumination means. effective.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a cross-sectional configuration of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing an external configuration of a CCD.

FIG. 3 is a cross-sectional view of a photo sensor.

FIG. 4 is an enlarged view of a photo sensor.

FIG. 5 is a timing chart of a density reproduction control operation in the printer unit.

FIG. 6 is a block diagram showing the flow of an image signal in the signal processing unit of the image scanner unit.

FIG. 7 is a diagram showing the timing of each control signal in the signal processing unit.

FIG. 8 is a diagram illustrating a light emission amount at a main scanning position of a white LED illumination module and an illuminance on a CCD surface.

FIG. 9 is a block diagram showing a configuration of an image scanner unit.

FIG. 10 is a diagram showing a configuration of a white LED.

FIG. 11 is a diagram illustrating a white LED lighting module in which an LED row is formed.

FIG. 12 is a diagram illustrating PWM control of LEDs.

FIG. 13 is a diagram illustrating a structure of an LED.

FIG. 14 is a diagram illustrating spectral characteristics of a white LED.

FIG. 15 is a diagram illustrating a color tone rank of a white LED on a chromaticity diagram.

FIG. 16 is a flowchart regarding ranking.

FIG. 17 is a diagram illustrating details of an input masking unit.

[Explanation of symbols]

200 Printer section 201 Image scanner section 202 Document platen 203 Platen glass 204 manuscript 205 white LED array 206, 207 mirror 208 lens 2103 line sensor 211 Standard white plate 2101, 1022, 2103 R, G, B sensors 212 laser driver 213 Semiconductor laser 214 polygon mirror 215 f-θ lens 216 Mirror 217 Photosensitive drum 219 Magenta Developer 220 cyan developer 221 yellow developer 222 Black developer 223 Transfer drum 224,225 Paper cassette 226 fixing unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/04 101 H04N 1/04 D 1/60 1/40 DF term (reference) 5B047 AA01 AB04 BB02 BC05 BC09 BC12 BC14 CB04 DC13 5C051 AA01 BA03 DA03 DA06 DB01 DB07 DB22 DB24 DB28 DC03 DC05 DE19 EA01 5C072 AA01 BA19 CA02 DA02 DA04 EA05 FA08 QA10 UA18 5C077 LL19 MM03 MP02 PP02 PP37 PQ12 TT06 LA02B02 JA23 H02B02 JA23B01

Claims (23)

[Claims] 1. An irradiation unit in which a plurality of light sources for irradiating a subject image are arranged, and a subject image emitted by the irradiation unit is read.
A photoelectric conversion unit that outputs the signal, a rank setting unit that sets the color tone rank of the plurality of light sources, a signal correction unit that corrects the first signal output by the photoelectric conversion unit, And calculate the first data,
An image reading apparatus comprising: a control unit that controls correction by the signal correction unit based on the first data. 2. The image according to claim 1, wherein the rank is divided into regions divided into regions occupying a predetermined area on an XYZ colorimetric system chromaticity diagram. Reader. 3. The image reading apparatus according to claim 1, wherein the signal correction means performs matrix calculation. 4. The image reading apparatus according to claim 1, wherein the irradiation units are arranged in an array in the main scanning direction. 5. The image reading device according to claim 1, wherein the light irradiating means is composed of a plurality of light sources having the same rank. 6. The image reading apparatus according to claim 1, wherein the light source has a fluorescent material. 7. A control method of an image reading apparatus having an irradiation unit in which a plurality of light sources for irradiating a subject image are arranged, wherein a rank setting step of setting a color tone rank of the plurality of light sources, and the irradiation unit. Read the illuminated subject image 1st
And a signal output step of calculating the first data according to the rank, and controlling to correct the output first signal based on the first data. A control method characterized by the above. 8. The rank is divided into areas which are divided into areas occupying a predetermined area on an XYZ colorimetric system chromaticity diagram.
The control method described in. 9. The control method according to claim 7, wherein the first data includes a matrix coefficient. 10. The control method according to claim 7, wherein the irradiation units are arranged in an array in the main scanning direction. 11. The control method according to claim 7, wherein the light irradiating means is composed of a plurality of light sources having the same rank. 12. A program executable by an information processing apparatus having a program code for implementing the image processing method according to claim 7. Description: 13. A storage medium storing the program according to claim 12. 14. A plurality of light sources for illuminating a subject image are firstly arranged.
The irradiation means arranged in the direction of, the photoelectric conversion means for reading the subject image irradiated by the irradiation means and outputting a signal, and the second signal output from the photoelectric conversion means based on the first data. An image having control means for performing correction so that the first data is data calculated from a first signal output from the photoelectric conversion means and information relating to the first direction. Reader. 15. The image reading apparatus according to claim 14, wherein the first data is calculated for each of a plurality of light sources arranged in the first direction. 16. The irradiating means has a plurality of groups each including a plurality of light sources in the first direction, and
The image reading device according to claim 14, wherein the first data is calculated for each of the plurality of groups. 17. The image reading device according to claim 14, wherein the first data includes a matrix coefficient. 18. A plurality of light sources for irradiating a subject image are firstly arranged.
A method of controlling an image reading apparatus having irradiation means arranged in the direction of, wherein a signal output step of outputting a reading signal of a subject image irradiated by the irradiation means, and the photoelectric conversion means based on first data. And a control step of controlling to correct the second signal output from the photoelectric conversion means, the first data is obtained from the first signal output from the photoelectric conversion unit and the information related to the first direction. A control method characterized by being calculated data. 19. The control method according to claim 18, wherein the first data is calculated for each of the plurality of light sources arranged in the first direction. 20. The irradiating unit has a plurality of groups each including a plurality of light sources in the first direction, and
20. The control method according to claim 18, wherein the first data is calculated for each of the plurality of groups. 21. The control method according to claim 18, wherein the first data includes a matrix coefficient. 22. A program executable by an information processing apparatus, having a program code for implementing the image processing method according to claim 18. 23. A storage medium storing the program according to claim 18.