JP3230282B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line scanning type image reading apparatus used as image input means for digital copying machines, facsimile machines, filing systems and the like.

[0002]

2. Description of the Related Art A line scanning type image reading apparatus has a one-dimensional image sensor composed of a large number of light receiving elements arranged in a main scanning direction. The original is subdivided into pixels and read by relatively moving the original in the sub-scanning direction.

Conventionally, in this type of image reading apparatus, there has been known an image reading apparatus in which a plurality of image sensors are arranged in parallel in a sub-scanning direction at a distance from each other. That is, in the case of reading a multicolor document including full color and performing color discrimination, a three-color integrated sensor in which image sensors of R (red), G (green), and B (blue) are integrated into one chip is used. ing. In addition, even when performing mono-color reading, if the optical system is of the same magnification type, multiple image sensors must be staggered along the main scanning direction in order to sufficiently increase the reading length in the main scanning direction. Is used.

When a plurality of image sensors are arranged in the sub-scanning direction as described above, a reading time difference depends on the distance (gap) between the image sensors. That is, the image sensor on one end side in the arrangement direction reads the original document ahead of the image sensor on the other end side, and the read position (line) of the original document at each image sensor at the same time is different.

Therefore, image data of the same line in a document read by each image sensor (a signal obtained by quantizing the photoelectric conversion output of the image sensor) is simultaneously output, or based on two-color image data for the same pixel. In order to determine the color of a pixel, it is necessary to perform correction corresponding to the difference in the reading position.

In such a conventional image reading apparatus, as such correction, transmission of image data corresponding to an image sensor for reading an original in advance is performed by using a delay memory (eg, FIFO).
In such a case, a process of delaying each line is performed.

That is, assuming that the gap between the image sensors is g, the magnification of the optical system (projection magnification of the original) is F, and the pixel density (number of lines / unit length) in the sub-scanning direction on the original is Dy. A displacement of the reading position corresponding to the number n of lines represented by the equation (1) occurs between the image sensors.

N = (g / F) × Dy (1) Therefore, the conventional image reading apparatus sequentially stores image data for n lines of the image sensor for reading the original document in the delay memory after temporarily storing the image data in the delay memory. It was configured to read.

[0009]

For example, in an image reading apparatus incorporated in a copying machine, the reading magnification M is changed according to the copying magnification. That is, the reading pixel density Dy in the sub-scanning direction is changed to a value (Dy = Ds × M) obtained by multiplying the reference reading pixel density Ds when the reading magnification is “1” (100%) by the reading magnification M. . As a method of changing the reading pixel density, the reading cycle (driving timing of the image sensor) is fixed, and the relative moving speed (sub-scanning speed) between the image sensor or the optical system and the document is set to a speed of 1 / M of the reference speed. The general method is to change to

Normally, the reference read pixel density Ds and the magnification F of the optical system are set so that the number of lines (hereinafter referred to as the number of different lines) n corresponding to the deviation of the reading position becomes an integer. Therefore, the reading magnification M is an integer (however,
In the case of (excluding 0), the difference line number n is also an integer, and thus, in principle, by delaying the period corresponding to the scanning of n lines as described above, the difference n The inconvenience of doing is completely eliminated.

However, in practice, unevenness in the sub-scanning speed (difference between the target speed and the actual speed) occurs, and therefore, the number n of difference lines may be a small number. This means that the line read by each image sensor causes a positional shift on the document in addition to a temporal shift in reading. For example, if the difference line number n is 13.1, the difference between the 13th line read by one image sensor and the first line read by the other image sensor is the fractional part of the difference line number n below the decimal point. A corresponding positional shift of 0.1 line occurs.

That is, when the sub-scanning speed fluctuates,
As disclosed in JP-A-3-22677, after replacing the difference line number n (decimal number) with an integer close thereto, n
By performing the delay for the lines, for example, the image data of each image sensor that is output simultaneously can be used as information of a close position on a document, but cannot be information of the completely same position.

For this reason, in an image reading apparatus that performs full-color reading, when an image is reproduced based on output image data of three colors of R, G, and B, there is a problem that colors are not reproduced correctly. In the image reading apparatus that performs the color determination of the pixel, there is a problem that an erroneous determination occurs, and when the image is reproduced based on the color determination data, the outline of the area of the color to be determined is disturbed. Further, even in an image reading apparatus that performs reading using a plurality of image sensors arranged in a staggered manner, there is a problem that an image reproduced based on output image data is disturbed.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an image reading apparatus that outputs high-quality image information excellent in image reproducibility regardless of fluctuations in the sub-scanning speed.

[0015]

According to a first aspect of the present invention, there is provided a line scanning type image reading apparatus having a plurality of image sensors arranged in a sub-scanning direction and parallel to each other. Reading position correcting means for performing correction corresponding to the difference between the reading positions of the respective image sensors, and detecting the amount of change in the sub-scanning speed during scanning of the original, and correcting the reading position in accordance with the detected amount of change. Correction means for setting the content of the correction by the means.

According to a second aspect of the present invention, the reading position correcting means performs a load averaging process on image data of a plurality of lines read by at least one image sensor at a ratio according to a sub-scanning speed. In addition, there is provided a data interpolation means for outputting the obtained image data as image data of a line corresponding to a line read by another image sensor.

According to a third aspect of the present invention, in the apparatus, the correction control unit determines a ratio of the load averaging process by the data interpolation unit in accordance with a difference in a reading position due to two factors, that is, a change in a sub-scanning speed and a reading magnification. The ratio is set.

[0018]

According to the relationship between the gap between the image sensors arranged in the sub-scanning direction and the sub-scanning speed, a displacement corresponding to a predetermined number of lines occurs at the reading position of each image sensor. It changes subtly according to.

The reading position correcting means performs a correction corresponding to such a positional deviation, for example, a delay in transmission of read information read in advance. At this time, the correction control means sets the correction content such as the delay amount according to the fluctuation amount of the sub-scanning speed.

The data interpolation means is provided as one means of correction corresponding to the positional deviation, and performs load averaging processing at a ratio set by the correction control means. Here, FIG.
As shown in the figure, the line L20 read by the other image sensor has a line width Y (length of the pixel q in the sub-scanning direction) of 4 in front of the line L10 read by the other image sensor in the sub-scanning direction. If it is shifted by one-half length,
That is, a case where a positional shift of 0.25 lines occurs between the image sensors is illustrated.

In the case of this example, the line L10 and the line L
20 overlap each other by 75%. The data interpolation means applies a load averaging process to the image data from one image sensor and corrects the processed image data from the other image sensor in order to correct the positional deviation between the line L10 and the line L20 as shown in the figure. Output as image information corresponding to the image data.

That is, the data interpolation means multiplies the image data of, for example, the line L10 and the next line L11 by a coefficient of a ratio (0.75 and 0.25) according to the degree of overlap with the line L20. Then, the obtained image data is output as image data corresponding to the line L20.

[0023]

FIG. 1 is a front view showing a schematic configuration of an image reader 1 according to the present invention. The image reader 1 is a line scanning type image reading device having a full color image sensor (hereinafter referred to as "image sensor") 16, and is a page printer (not shown) as an image input means of a digital copying machine having a multicolor copying function. Used in combination with

The optical system 10 for projecting a document image on the image sensor 16 includes a scanner 11, mirrors 13 and 14, which can reciprocate below a platen glass 18, a main lens 15, and the like. The scanner 11 has an exposure lamp 12 that irradiates scanning light to a document, and is driven by a motor 17. The scanning light reflected on the surface of the original is
The light enters the image sensor 16 via the main lens 14 and the main lens 15.

The original image is read by the image sensor 16 as color signals of three primary colors of R (red), G (green), and B (blue). The photoelectric conversion signal output from the image sensor 16 is quantized by the signal processing unit 100, subjected to various signal processing according to the copy mode, and then sent to the page printer as image data VIDEO.

Here, the multicolor copy mode of the copying machine using the image reader 1 will be described. In a normal copying mode, a copying machine forms a monochromatic image of a standard color (generally black) regardless of the color of a document. On the other hand, in the multi-color copy mode, the designated color portion in the document image is copied in a color other than the standard color (for example, red), and the other color portions are copied in the standard color. That is, an image of two colors is formed. At this time, two colors, red and blue, can be selected as the designated colors. The designated color is selected by the operator using keys on the operation panel.

In order to realize such a multi-color copy,
In the image reader 1, the color of each pixel of the document image is determined (color determination) in the signal processing unit 100 described later. Then, the color data Dco obtained by the determination is output to the page printer in synchronization with the image data VIDEO.

FIGS. 2A and 2B show the image sensor 1.
6 is a plan view schematically showing the configuration of FIG. FIG. 2B is an enlarged view of a part of FIG. Image sensor 16
Is a one-chip solid-state imaging device in which three CCD arrays 16R, 16G, and 16B extending in the main scanning direction of document scanning are integrally formed on a substrate. Each CCD array 16R, 16
G and 16B represent C corresponding to 5000 pixels, respectively.
It has a CD element and can read A3 size documents at a resolution of 16 lines / mm. CCD array 16R, 1
The light receiving surfaces of 6G and 16B are provided with spectral filters that transmit R, G, and B light, respectively, in order to separate and read the original image into three primary colors.

In the image sensor 16, the CCD array 1
6R, 16G and 16B are arranged in parallel in the sub-scanning direction at a pitch of 12 pixels. For this reason, for the same pixel, the output timing of the photoelectric conversion signal by the CCD array 16G is a certain time (1 when the reading magnification is “1”) with respect to the output timing of the CCD array 16R.
The output timing of the CCD array 16B is delayed by the same time as the output timing of the CCD array 16G. That is, the information of each color read by separating the pixel into three colors is R,
It is output in the order of G and B with a delay of a fixed time. Since the sub-scanning speed is changed according to the copy magnification, the deviation of the output timing of each color also increases or decreases according to the copy magnification.

FIG. 3 is a block diagram showing the configuration of the signal processing unit 100. The signal processing unit 100 includes the image reader 1
An AD converter 110, a shading corrector 120, and a CPU (central processing unit) 101 that controls the whole
Position correction unit 130, image processing unit 140, output interface unit 150, color determination unit 160, and clock generation unit 1
80 and the like.

The image sensor 16 described above responds to a CCD drive signal given from the clock generator 180
The photoelectric conversion signals of the respective colors of R, G, and B are sent to the signal processing unit 100 in parallel.

In the signal processing unit 100, first, the AD conversion unit 110 quantizes the photoelectric conversion signal of each color. That is, the AD converter 110 amplifies the photoelectric conversion signal of each color to a predetermined level, performs sampling at a timing according to a pixel clock, and converts the photoelectric conversion signal into 8-bit (256 gradation) image data for each color. . The pixel clock is also generated by the clock generator 180.

Thereafter, various processes are performed using the image data generated by the AD converter 110 as original information.
Hereinafter, the operation of each unit will be described. The shading correction unit 120 performs shading correction on image data of three colors corresponding to uneven light distribution of the exposure lamp 12 and a sensitivity difference between pixels of the CCD array, and correction for normalizing a dynamic range between colors. And do.

The position correction unit 130 selects two color (G and R or G and B) image data required for color discrimination from the three color image data, and The delay processing and the interpolation processing for compensating for the difference between the reading positions of the CCD arrays 16R, 16G, and 16B are performed. Then, the position correction unit 130 extracts the G image data having the highest relative luminous efficiency among R, G, and B as monochrome read information (density data) of the document and outputs the information to the image processing unit 140. The R or B image data is converted to a color
Output to

For such a position correction unit 130, C
PU 101 includes a select signal SS, delay amount data DL,
And interpolation ratio data DH. The position correction unit 1
Details of the configuration of 30 will be described later.

The color discriminating section 160 is composed of a ROM in which predetermined data is stored as a look-up table (LUT), and the two-color image data selected by the position correcting section 130 and the designated color bit signal Sco input from the CPU 101.
And outputs color determination data in which the color of the document image is determined for each pixel. That is, in the ROM, the address specified by the value of the designated color signal bit Sco and the respective values “0” to “255” of the image data of two colors are stored.
In each case, data indicating the value of the color determination data is stored.

The image processing unit 140 performs various image processing on the G image data, including gamma correction for correctly reproducing the density of the original image, and filtering processing such as edge enhancement and smoothing for improving the image quality. Add.

Further, the image processing unit 140 includes a scaling unit 14 that performs pixel density conversion (a scaling process of overlapping pixels or thinning out pixels) in the main scanning direction according to the scaling data MAG.
5 are provided. The magnification data MAG is stored in the CPU 10
This value is appropriately changed according to the reading magnification according to the copying magnification.

To the scaling unit 145, color discrimination data from the color discrimination unit 160 is also input in synchronization with the G image data, and the output data is subjected to a scaling process similarly to the image data.

The G image data and the color discrimination data output from the image processing unit 140 are respectively image data VID
The data is transferred to the page printer via the output interface unit 150 as EO and color data Dco.

The output form of the image data VIDEO may be an 8-bit digital signal indicating the image density, or may be bit data binarized by a dither method or the like. Further, it may be an analog signal.

In parallel with the control of the signal processing unit 100 having the above configuration, the CPU 101 controls the scanning speed in order to set the pixel density in the sub-scanning direction to a value corresponding to the reading magnification. That is, the CPU 101 controls the driver 17D that drives the scanning motor 17 to output the switching signal S
d, and controls the motor 17 based on the output pulse signal F / G of the motor rotation sensor 17S.
And a speed control signal Sv is given to the driver 17D so that the scanning speed becomes a constant speed corresponding to the reading magnification.

The scan speed is set to a value represented by the equation (2). V = Vs / M (2) where Vs is the reference scanning speed when the reading magnification is “1” (100%), and M is the reading magnification.

That is, the reading magnification is "2" (200%)
If so, the scan speed is half of the reference scan speed
If the reading magnification is "0.5" (50%), the scanning speed is twice the reference scanning speed.

By setting the scanning speed in this manner, as described above, the reading pixel density Dy in the sub-scanning direction is changed to the reference reading pixel density Ds when the reading magnification is "1". (Dy = Ds)
× M).

FIG. 4 is a block diagram showing the configuration of the position correction unit 130 shown in FIG. The position correction unit 130 is a selector 131 that selects and outputs image data of two colors out of three colors,
A selector 132 for switching the transmission destination of the two-color image data, a line delay unit 133 for delaying data for a plurality of lines, and a line memory 1 for delaying data for one line
34, and a data interpolation unit 135 that performs a weighted average process as the interpolation process.

In the selector 131, if the designated color for color discrimination is red, R and G image data is selected, and if the designated color is blue, G and B image data are selected. Of the two color image data selected in this way, the image data corresponding to the CCD array on the side where the original is read first is sent to the line delay unit 133, and the other image data is sent to the selector 132. Sent as input.

The line delay unit 133 outputs the delay amount data DL
, The input image data is output after being delayed by a predetermined time in line units. The number k of delay lines of the line delay unit 133, that is, the value of the delay amount data DL is set to the same number as the number n of different lines (the number of lines corresponding to the gap between the CCD arrays) or an integer closest thereto.

For example, when the reading magnification is "1",
The difference line number n is “12”. Therefore, at this time, the CPU 101 sets “12” as the number k of delay lines.
Set. Then, the line delay unit 133 sequentially stores the image data of the 12th line in the internal memory, reads out the image data of the first line in parallel with the storage of the 13th line, and inputs the readout image data to the selector 132 as the other selection input. send. When the reading magnification M is “2”, the scan speed is の of the normal speed, and the difference line number n is “24” (12 × 2). Therefore, at this time, the line delay unit 133 delays for 24 lines.

When the number n of different lines becomes an integer due to such a line-by-line delay, the two-color image data input to the selector 132 becomes information obtained by reading the same line on the document.

However, depending on the value of the reading magnification M, the difference line number n may be a decimal number. For example, when the reading magnification M is “1.10”, the difference line number n is “1”.
3.2 "(12 × 1.10).

In such a case, a difference occurs between the number n of different lines and the number k of delay lines. This is the selector 1
It is assumed that the two-color image data input to 32 is information on a line shifted by a distance x (0 <x <Y) smaller than the line width (line pitch) Y on the document as shown in FIG. means.

On the other hand, even if the reading magnification M is an integer, if the scanning speed becomes uneven, the positions on the document corresponding to the two color image data are slightly different, and the difference line number n and the delay There is a difference with the number of lines k.

That is, considering the unevenness of the scanning speed, the difference line number n can be expressed by the following equation (3). n = 12 × M ± α (3) Here, α is a value depending on the unevenness of the scanning speed.

Therefore, the data interpolation unit 135 is provided to compensate for the difference between the number n of different lines and the number k of delay lines. The data interpolation unit 135 generates interpolation data for one of the two-color image data by a weighted average of the data values of the pixels on two adjacent lines, and uses the interpolation data as image data corresponding to the other image data. Send to color discriminating section 160. The load coefficient of the load average is specified by the interpolation ratio data DH. For example, if the difference between the difference line number n and the delay line number k is “0.25”, the data interpolation unit 135 uses the data of two lines as 0.25 to 0 as described with reference to FIG. The weighted average processing at a ratio of 0.75 is performed to generate one line of interpolation data. The line memory 134 is provided as delay means for averaging the weights of two lines.

The selector 132 sends one R or B image data of the input two-color image data to the data interpolation unit 135 and sends the other G image data to the image processing unit 140 as it is. Switch the transmission path as follows.

In other words, the position correction unit 130 holds information contents of the G image data as the image data VIDEO as much as possible to improve the reproducibility of the image.
The G image data is excluded from the weighted average (interpolation processing).

FIG. 5 is a circuit diagram showing a configuration of the line delay unit 133 of FIG. In FIG. 5, the line delay unit 133
Is a FIFO memory 310 having a storage capacity capable of storing image data for 52 lines, a sub-scanning counter 320 for counting a horizontal synchronization signal Hsync input for each scanning of one line, comparators 330 and 340, and various logic circuits. 351-355.

For example, when the reading magnification is “1”, first, “5” is set as the comparison target value of the comparator 330.
2 ”(the number of fixed lines) is set, and the comparator 340 is set.
Is set to the value "12" (the number of delay lines) of the delay amount data DL.

Next, when the scanning start instruction signal SCAN is input, the count value of the sub-scanning counter 320 is cleared. As a result, all bits indicating the count value of the sub-scanning counter 320 become “0”, so that the write reset signal WRST for the FIFO memory 310 becomes active. Therefore, the write address of the FIFO memory 310 is reset, and the input image data is stored in the FIFO memory 310.
The data is written to the memory 31 in order from the head address.

After the reset of the write address, the read reset signal RRST becomes active at the time of scanning the twelfth line, and the write address of the FIFO memory 310 is reset. Therefore, thereafter, reading is performed sequentially from the head address.

Thereafter, at the time of scanning the 52nd line, the output of the comparator 330 becomes active, and the FIFO
The write address of the memory 310 is reset. That is, writing and reading of image data are repeatedly performed in a cycle of 52 lines.

FIG. 6 is a block diagram showing an example of the data interpolator 135 of FIG. 4, and FIGS. 7 and 8 are block diagrams showing other examples of the data interpolator 135 of FIG. In addition,
7 and 8, components having the same functions as those in FIG. 6 are denoted by the same reference numerals, and components corresponding to FIG. 6 are denoted by the same reference numerals with alphabets “a” and “b” added. I have.

In FIG. 6, the data interpolation unit 135
It is composed of two multipliers 511 and 512 and an adder 513. The multiplier 511 is connected to the selector 13 shown in FIG.
The image data having a value obtained by multiplying the value of the image data of the (N + 1) -th line directly input from 2 by the load coefficient DC2 is output. Further, the multiplier 512 is connected to the line memory 134.
Then, image data having a value obtained by multiplying the value of the N-th image data delayed by the weighting factor DC1 is output.

The adder 513 comprises multipliers 511 and 512
Is output as image data. Assuming that the weights of the load coefficients DC1 and DC2 are a% and (100−a)%, respectively, the interpolation data is [N +
It becomes image data corresponding to the (100-a) / 100] th line.

FIG. 6 illustrates a configuration using the multipliers 511 and 512, but as shown in FIG.
Lookup table ROMs 511a and 51
2a may be used. 6 and 7, the multipliers 511 and 512 or the look-up table ROM 5 are used.
By appropriately selecting the bit configuration of 11a and 512a, fine interpolation can be realized.

Also, as shown in FIG.
523, the adder 531 and the multiplier 540 can be combined to perform interpolation. In the example of FIG. 8, assuming that the data values of the Nth line and the (N + 1) th line are A and B, respectively, A, (3A + B) / 4, and (2A + 2) are obtained by combining the select signals SS1 to SS3.
Four types of interpolation data B) / 4 and (A + 3B) / 4 can be obtained. That is, it is possible to realize interpolation on a quarter line basis. By increasing the number of selectors and adders, it is possible to perform interpolation with a precision of a quarter line unit or more. In this case, it is preferable to set the interpolation accuracy to a unit of one power of 2 in order to simplify the circuit configuration.

FIG. 9 is a flowchart showing an outline of the interpolation ratio setting processing executed by the CPU 101. CPU10
1 generates the interpolation ratio data DH corresponding to the reading magnification M in consideration of the unevenness of the scanning speed as described above.

That is, the CPU 101 detects the scanning speed by measuring the pulse period of the output pulse signal F / G by an internal timer, and determines a predetermined speed based on the difference between the normal speed corresponding to the reading magnification M and the measured value. Is calculated by the calculation of (#).
10).

Note that, depending on the relationship between the required time for scanning speed detection depending on the processing speed of the CPU 101 and the transmission timing of the image data, a delay for the image data may be required.

Next, the CPU 101 determines the number k of delay lines and the load coefficients DC1 and DC2 (# 20). For example, when the reading magnification M is “1” and the positional shift amount due to the scan speed unevenness is “+0.1”, that is, when the scan speed is faster by 0.1 lines, the difference line number n is “1”. 11.9 ", the delay line number k is set to" 11 ", the load coefficient DC1 corresponding to the N-th line is set to" 0.1 ", and the load coefficient DC1 corresponding to the (N + 1) -th line is set to" 11 ". “0.9” is assumed.

When the reading magnification M is "1", the amount of positional deviation due to the scanning speed unevenness is "-0.
1 ", that is, when the scan speed is slower by 0.1 line, the number n of difference lines becomes" 12.1 ". Therefore, the number k of delay lines is set to" 12 ", and the load coefficient D
Let C1 and DC2 be "0.9" and "0.1", respectively.

Further, when the reading magnification M is "1.1" and the positional deviation amount due to the scanning speed unevenness is "+0.1", the difference line number n becomes "13.
1 "(12 * 1.1-0.1), the number k of delay lines is set to" 13 ", and the load coefficients DC1 and DC2 are set to" 0.9 "and" 0.1 ", respectively.

Then, the CPU 101 sets the delay line number k
Is the delay amount data DL, the load coefficients DC1 and DC2 are the interpolation ratio data DH, and these data are
30 (# 30).

FIG. 10 is a block diagram showing a configuration of a signal processing unit 100A according to another embodiment of the present invention, and FIG.
FIG. 4 is a block diagram illustrating a configuration of a position correction unit 130A.
In these figures, components having the same functions as those in FIGS. 3 and 4 are denoted by the same reference numerals, and components corresponding to FIGS. 3 and 4 are denoted by the same reference numerals with the letter “A” added thereto. I have.

In FIG. 10, the signal processing unit 100A
Three-color image data V for reproducing full-color images
It is configured to output IDEO. The position correction unit 130A is provided to compensate for the difference in the reading positions of the three color image data input from the shading correction unit 120. A CPU is provided for the position correction unit 130A.
101A is the delay amount data DLA and the interpolation ratio data D
H1 and DH2 are given.

The image processing section 140A has a scaling section 145A and performs various image processing including pixel density conversion in the main scanning direction. The three-color image data VIDEO processed by the image processing unit 140A is output in parallel via the output interface unit 150A.

As shown in FIG. 11, the position corrector 130A
Is a delay memory 31 provided for the R image data.
1, line memory 134, interpolation unit 135, delay memory 312 provided for G image data, line memory 134, interpolation unit 135, and delay memories 311 and 31
2 and a delay control unit 313 for controlling the position of the R and G image data read from the B image data.

Since the CCD arrays 16R, 16G, and 16B are arranged at equal intervals, the number n of different lines related to the R image data is twice the number n of different lines related to the G image data. Therefore, the delay memory 311 has the delay line number kR as the delay line number kR.
Is set to twice the value of Similarly, each of the interpolation units 135
A load coefficient is set for.

For example, when the reading magnification M is “1.1”, it is assumed that there is no scan speed unevenness, the difference line number n relating to the G image data is “13.2”, and the R image data Is 26.4. Accordingly, the G image data is delayed by 13 lines by the delay memory 312, and the interpolation unit 1
35 for the N and (N + 1) th lines.
A load averaging process with a ratio of 8 to 0.2 is performed. Also, R
Of the image data of 26
The delay for the line is performed, and the interpolation unit 135 performs the load averaging process on the Nth and (N + 1) th lines at a ratio of 0.6 to 0.4.

According to the embodiment of FIG. 3 described above, the G image data having the highest relative luminous efficiency among the three colors is output as the density data without performing the load averaging process. Reproducibility can be improved. In addition, the color discrimination information has high quality, and a multicolor image can be formed without any disturbance in the outline of the designated color.

According to the above-described embodiment, since the one-chip image sensor 16 in which the CCD arrays 16R, 16G, and 16B corresponding to R, G, and B are integrated is used, an individual image sensor is provided for each color. Compared to the case of providing, the relative position accuracy of the light receiving surface of each color is high, and the influence of lens aberration and temperature change is small, so that it is possible to obtain image data in which the original image is correctly separated. Therefore, there is no erroneous color determination, and no color ghost due to erroneous determination occurs.

In the above-described embodiment, the image reader 1 using the full-color image sensor 16 has been illustrated. However, the present invention is also applicable to an image reading apparatus that performs mono-color reading using a plurality of staggered image sensors. The invention can be applied.

In the above-described embodiment, the correction by the line delay unit 133 and the interpolation unit 135 has been described as the correction corresponding to the difference in the reading position between the CCD arrays. In such a case, the correction by the line delay unit 133, that is, only the data delay may be performed. In this case, a value obtained by rounding off the difference line number n can be set as the delay line number.

In the above-described embodiment, the predetermined delay can be performed by using a delay unit other than the FIFO memory.
For three colors, for example, one page (one document)
May be stored in the page memory, and an appropriate line may be selected to simultaneously read out three colors.

In the above embodiment, the image reader 1 for a copying machine has been described as an example, but the application of the image reading apparatus according to the present invention is not limited to this. For example, an image reader device that forms a filing system together with an external host computer or the like may be used.

[0087]

According to the present invention, it is possible to output high quality image information excellent in image reproducibility irrespective of fluctuations in the sub-scanning speed.

According to the second aspect of the invention, it is possible to output higher quality image information. According to the third aspect of the invention, high-quality image information can be output regardless of the reading magnification.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of an image reader according to the present invention.

FIG. 2 is a plan view schematically showing a configuration of a full-color image sensor.

FIG. 3 is a block diagram illustrating a configuration of a signal processing unit.

FIG. 4 is a block diagram illustrating a configuration of a position correction unit in FIG. 3;

FIG. 5 is a circuit diagram illustrating a configuration of a line delay unit in FIG. 4;

FIG. 6 is a block diagram illustrating an example of a data interpolation unit in FIG. 4;

FIG. 7 is a block diagram illustrating another example of the data interpolation unit in FIG. 4;

FIG. 8 is a block diagram illustrating another example of the data interpolation unit in FIG. 4;

FIG. 9 is a flowchart illustrating an outline of an interpolation ratio setting process executed by a CPU;

FIG. 10 is a block diagram illustrating a configuration of a signal processing unit according to another embodiment of the present invention.

11 is a block diagram illustrating a configuration of a position correction unit in FIG.

FIG. 12 is a diagram for explaining the contents of a load averaging process.

[Explanation of symbols]

Reference Signs List 1 image reader (image reading device) 16R, 16G, 16B CCD array (image sensor) 130 position correction unit (reading position correction unit) 101 CPU (correction control unit) 135 interpolation unit (data interpolation unit)

Claims (3)

(57) [Claims] 1. A line scanning type image reading apparatus having a plurality of image sensors arranged in parallel in a sub-scanning direction, wherein a reading position correction is performed in accordance with a difference in a reading position of each of the image sensors. Means for detecting the amount of change in the sub-scanning speed during document scanning, and correcting control means for setting the content of correction by the reading position correcting means according to the detected amount of change. Reader. 2. The image processing apparatus according to claim 1, wherein the reading position correcting means applies a load averaging process to image data of a plurality of lines read by at least one image sensor at a ratio according to a sub-scanning speed, and obtains the obtained image data. 2. The image reading apparatus according to claim 1, further comprising data interpolation means for outputting as line image data corresponding to a line read by another image sensor. 3. The method according to claim 2, wherein the correction control means calculates a ratio of the weighted average processing by the data interpolation means.
3. The image reading apparatus according to claim 2, wherein a ratio is set in accordance with a difference in a reading position due to two factors, a change in a sub-scanning speed and a reading magnification.