JP4371717B2 - Image reading device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus mounted on a copying machine, a scanner, a facsimile machine or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image reading apparatus mounted on an image forming apparatus such as a copying machine, a scanner, or a facsimile, each original is placed on the original reading position in order to correct fluctuations in the light quantity and light distribution of the light source. The density reference member is monitored, and correction is performed based on the variation amount (see, for example, Patent Document 1 and Patent Document 2).
[0003]
[Patent Document 1]
JP-A-9-74465 [Patent Document 2]
Japanese Patent Laid-Open No. 10-257314 [0004]
[Problems to be solved by the invention]
However, in the above-described conventional method, particularly when the density reference member at the original reading position is a roller and a part of the roller is dirty, the rotation of the roller monitors the dirt at a certain cycle. There was a problem that the image suddenly deteriorated.
[0005]
In view of the above-described conventional problems, an object of the present invention is to provide an image reading apparatus capable of preventing sudden image deterioration during light amount fluctuation correction.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an image reading apparatus according to the present invention includes a reading unit that reads a document at a reading position while conveying the document, and shading the document data read by the reading unit using a reference white plate. and shading correction means for performing correction processing, in order to perform the roller for the document transport disposed on the reading position of the document, and the surface of the roller to get the read light intensity variation data correction of light amount variation, shading correction And a gain correction unit configured to correct the gain of the processed document data. The gain correction unit is configured to gain based on data weighted to a plurality of light amount fluctuation data read at predetermined intervals. data is calculated, using the gain data, to correct the gain of the original data shading correction process And butterflies.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0008]
[First Embodiment]
<Device configuration>
FIG. 1 is a cross-sectional view showing a schematic configuration of the image reading apparatus according to the first embodiment of the present invention, and FIG. 2 is a plan view of the image reading apparatus main body in FIG.
[0009]
In FIG. 1, the image reading apparatus includes an image reading apparatus main body 100 and an automatic document feeder (ADF) 200 configured to be detachable from the image reading apparatus main body 100.
[0010]
The original set on the paper feed tray 205 is conveyed onto the flow reading glass 122 of the image reading apparatus main body 100 by the conveyance rollers 203 and 204 and is discharged onto the paper discharge tray 206. At this time, the document passes between the platen roller 201 attached to the ADF 200 and the flow reading glass 122 of the image reading apparatus main body 100, and is optically scanned by the image reading apparatus main body 100 during the passage process. Is read.
[0011]
The image reading apparatus main body 100 includes a contact image sensor (hereinafter referred to as CIS) 110. The CIS 110 irradiates light on a document surface, and reflection from the document corresponding to the light irradiated by the lamp 111. A lens 112 for guiding light to the image sensor and an image sensor 113 for photoelectrically converting the light collected by the lens 112 are integrally housed in a housing 114.
[0012]
The CIS 110 is connected to the optical motor 125 by the timing belt 126 in FIG. 2, and is controlled to move in parallel with the document table glass 121 and the flow reading glass 122 by the rotational drive of the optical motor 125. The position sensor 124 is a sensor for detecting the home position of the CIS 110. By moving the optical motor 125 forward and backward based on the position of the position sensor 124, the CIS 110 is moved, and the platen glass 121 is scanned. The original on the glass 122 is optically scanned.
[0013]
The optical motor 125 is a stepping motor. The optical motor 125 can recognize how many pulses the CIS 110 has moved. That is, based on the detection signal of the position sensor 124 and the number of steps of the stepping motor, it is possible to grasp the position of the CIS 110 and control the movement.
[0014]
The reflected light from the document is guided by the Selfoc lens 112 and collected on the image sensor 113. The image sensor 113 photoelectrically converts the reflected light reflecting the document information and outputs it as an electronic image signal.
[0015]
With such a configuration, with the CIS 110 stopped at the document reading position, the ADF document reading mode in which document information is read while the document is conveyed by the ADF 200, and the document is fixedly placed on the document table glass 121. Document information can be read in two modes: a document glass table document reading mode that reads document information while moving the CIS 110 in the sub-scanning direction.
[0016]
FIG. 3 is a diagram illustrating a configuration in the vicinity of the CIS 110.
[0017]
The ADF 200 includes a white sheet member 210 on the upstream side of the platen roller 201 in the document conveyance direction. The white sheet member 210 is disposed substantially parallel to the flow reading glass 122. Further, the tip position 211 where the white sheet member 210 is closest to the platen roller 201 is the image reading range of the CIS 110 in the main scanning direction when the platen roller 201 and the white sheet member 210 are viewed from below in the drawing. Is arranged so as to hide a part of the platen roller 201. Further, the reading position of the CIS 110 in the ADF original reading mode is set to a position where the surface of the platen roller 201 is read when the original is not conveyed. The original platen glass 121 is provided with a reference white plate 127.
[0018]
FIG. 4 is a block diagram illustrating a schematic configuration of a control system of the image reading apparatus.
[0019]
In the figure, the image reading apparatus includes a platen roller 201 that conveys an original, a paper feed roller 202, conveying rollers 203 and 204, a lamp 111 that irradiates light on the original surface, and a CIS 110 that moves in the sub-scanning direction. , An image sensor 113 that photoelectrically converts light reflected from the document surface, an A / D conversion circuit 401 that performs A / D conversion on the output signal of the image sensor 113, and the CIS 110 are positioned at the home position. A position sensor 124, a backup RAM 403 for setting a normal document reading position in the ADF document reading mode, and a scanner controller 404. The scanner controller 404 is provided with a ROM 405 for storing a control program and the like.
[0020]
FIG. 5 is a block diagram illustrating a configuration of an image processing unit of the image reading apparatus according to the present embodiment.
[0021]
In the figure, an image signal from the image sensor is subjected to shading correction by a shading correction unit 501. The light amount fluctuation correction unit 502 connected to the shading correction unit 501 performs light quantity fluctuation correction, which will be described in detail later. The shading correction unit 501 is connected to memories (black memory 504 and white memory 505) for storing shading correction values, and the light amount variation correction unit 502 is connected to a gain memory 506 for storing light amount variation correction values. Has been.
[0022]
<Operation of the device>
FIG. 6 is a flowchart showing a continuous reading sequence of the image reading apparatus according to this embodiment.
[0023]
First, the CIS 110 reads the white reference white plate 127 on the home position, obtains shading correction data for each pixel, and sets a shading correction value in the white memory 505 (step S101). Thereafter, the CIS 110 moves to the reading position of the original (step S102), reads the surface of the platen roller 201, obtains light amount fluctuation correction data, and sets it in the gain memory 506 (step S103). Note that the light amount variation correction data may be prepared for each pixel in the gain memory 506. When a uniform gain value is used in the main scanning direction, one data may be prepared for each color. . In the present embodiment, since a uniform gain value is used in the main scanning direction, it will be described later assuming that there is one gain value for light quantity fluctuation correction for each color.
[0024]
After each correction data is obtained, the original is read (step S104). Then, the image data that has been read in CIS110 the shading correction and the light amount variation correction is performed (step S105). Furthermore, if there is a next original in step S106, the surface of the platen roller 201 is read again between the originals (when the original does not pass through the reading position) to read the original. On the other hand, if there is no next original in step S106, the original reading sequence is terminated.
[0025]
FIG. 7 is a flowchart for setting a light amount variation correction value in the image reading apparatus according to the present embodiment, and details step S103 in FIG. 6 described above. Here, the setting of the light amount fluctuation correction value for the Nth document will be described.
[0026]
First, the roller 201 on the reading position is read (step S201). The reading position of the roller 201 is shown in FIG. The roller read image area P, which is m pixels in the main scanning direction and n pixels in the sub scanning direction, is taken as one point, and a roller read value Ra that is a sample area of the area P is obtained. The roller reading in step 201 may be one point, but it is better to adopt a method of averaging the reading values of a plurality of points in order to make it less susceptible to dust.
[0027]
An average value R (N) ave of the Nth roller reading values is calculated by averaging the roller reading values for a plurality of points (a points) in the main scanning direction (step S202). The calculation formula is shown below.
[0028]
R (N) ave = (R1 + R2 + ... + Ra) / a
The method of calculating the gain value using the N-th roller reading value R (N) ave is as long as the reading value is almost equal between the first and N-th originals even if the amount of light is deteriorated. Taking advantage of this, the average value R (1) ave of the first roller reading value and the average value R (N) ave of the Nth roller reading value are compared. By this method, a gain value is obtained so that the amount of light quantity deterioration can be corrected, and correction is executed when the Nth document is read. The gain value GAIN (N) can be calculated from the following equation.
[0029]
GAIN (N) = R (1) ave / R (N) ave
Before calculating the gain value based on the average value of the roller reading values obtained in step S202, in the present embodiment, a step considering the following is performed.
[0030]
That is, as shown in FIG. 8, when the roller 201 is contaminated (W), the roller reading value becomes small, and the light quantity deterioration cannot be accurately calculated. Therefore, when correcting the Nth document, not only the Nth roller reading value R (N) ave but also the average value R (N-1) ave, N− of the N−1th roller reading value. An average value R (N-2) ave of the second roller reading values is used.
[0031]
FIG. 9 is a diagram showing a time-series read image at the time of flow reading of the image reading apparatus according to the present embodiment, and shows that the roller 201 and the document are read in time series.
[0032]
At this time, the roller 201 is rotating, and the position of the dirt (W) moves depending on the reading timing. As a result, the N-1 and N-2 roller reading values are also used for the Nth document, so that the influence of dirt (W) is reduced to 1/3 when the average is taken. be able to. That is, the light amount correction for the Nth document is executed by calculating a correction value based on the N, N-1, and N-2th roller reading values (step S203).
[0033]
A correction value calculation formula for performing gain correction on the Nth document using the Nth, N−1th, and N−2th roller reading values in step S203 is shown below.
[0034]
GAIN (N) = R (1) ave / ((R (N) ave + R (N-1) ave + R (N-2) ave) / 3)
Although the N-1 and N-2 roller reading values are used for the Nth document, any number of roller reading values may be referred to.
[0035]
Next, the limiter is adapted to the calculated correction value, that is, the gain value change amount (step S204). As shown in FIG. 10 showing the amount of change in the reading value of the roller 201, there may be a case where a sudden fluctuation Z occurs in the roller reading value due to the influence of dirt on the roller 201. In such a case, in order to prevent sudden image deterioration, it is necessary to keep the amount of change in the gain value with respect to the previous document within a predetermined range.
[0036]
Therefore, in this limiter, when the change amount between the calculated gain value and the gain value set at the time of the previous document is not within the predetermined range, the limiter is set so that the change amount of the gain value is within the range. multiply. That is, the gain value set for the previous document and the amount of change of the gain value calculated this time are always within a predetermined range. The predetermined range is desirably suppressed to a level where image deterioration is not noticeable.
[0037]
As described above, even when the appropriate gain value is not calculated due to the contamination of the roller 201 by the limiter, sudden image deterioration can be suppressed (step S204).
[0038]
The gain value calculated as described above is set in a predetermined gain memory (step S205), and the light amount fluctuation correction is terminated.
[0039]
[Second Embodiment]
In order to simplify the description, only the parts different from the first embodiment will be described.
[0040]
In the present embodiment, in the gain calculation process in step S203 in the flowchart for setting the light amount variation correction value (FIG. 7), the N, N-1 and N-2 roller reading values are weighted. The roller reading value immediately before the N-th roller reading value increases the specific gravity, and from the N-th sheet, the specific gravity of the N-2th roller reading value that is separated in time is decreased. The gain calculation formula at that time is shown below.
[0041]
GAIN (N) = R (1) ave / ((C1 * R (N) ave + C2
* R (N-1) ave + C3 * R (N-2) ave) / 3 )
However, C1 + C2 + C3 = 1, C1>C2> C3
In this way, for the Nth document, the fluctuation of the amount of light is changed using the Nth roller reading value, the N−1th roller reading value, and the N−2th roller reading value. Correct with gain. The number of references to the roller reading value is three, but any number is acceptable.
[0042]
Note that the above-described control method can be realized by storing and operating the program according to the flowcharts in FIGS. 6 and 7 in the ROM 405 in the scanner controller 404.
[0043]
The present invention is not limited to the apparatus of the above-described embodiment, and may be applied to a system composed of a plurality of devices or an apparatus composed of one device. A storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus reads and executes the program codes stored in the storage medium. Needless to say, it will be completed by doing.
[0044]
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. As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM is used. Can do. In addition, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also the OS running on the computer based on the instruction of the program code performs the actual processing. Needless to say, a case where the function of the above-described embodiment is realized by performing part or all of the processing is also included.
[0045]
Furthermore, after the program code read from the storage medium is written to the memory provided in the function expansion board inserted in the computer or the function expansion unit connected to the computer, the program code is expanded based on the instruction of the next program code. It goes without saying that the functions of the above-described embodiments may be realized by performing some or all of the actual processing by the CPU or the like provided on the expansion board or the expansion unit.
[0046]
[Embodiment]
Examples of embodiments of the present invention are listed below.
[0047]
<Embodiment 1> A reading unit that reads a document at a predetermined reading position while conveying the document, reads a reference member every time the document is read, and a correction unit that corrects a read image signal of the document read by the reading unit. And the correction means corrects the read image signal based on a plurality of signal data obtained by reading the reference member a plurality of times with time by the reading means. apparatus.
[0048]
<Embodiment 2> The image reading device according to Embodiment 1, wherein the correction unit obtains a correction value by taking an average of the plurality of signal data, and corrects the read image signal based on the correction value. apparatus.
[0049]
<Embodiment 3> Embodiment 1 wherein the correction means weights each signal data in the plurality of signal data to obtain a correction value, and corrects the read image signal based on the correction value. The image reading apparatus described.
[0050]
<Embodiment 4> The image reading apparatus according to any one of Embodiments 1 to 3, wherein the reading unit includes a light source that irradiates a document, and the correction unit corrects a light amount variation of the light source.
[0051]
<Embodiment 5> The image reading apparatus according to any one of Embodiments 1 to 4, wherein the correction unit corrects the read image signal so that a correction amount is within a predetermined range.
[0052]
<Embodiment 6> A light source that irradiates a document, a reading unit that photoelectrically converts reflected light from the document and reads information on the document, and a read image signal obtained by reading the document by the reading unit is corrected A first density reference member serving as a reference for performing the measurement, a second density reference member different from the first density reference member, and the second density reference member by the reading means a plurality of times at intervals. Comparing means for comparing a plurality of signals obtained by reading, and the reading based on the first signal obtained by reading the first density reference member by the reading means and the comparison result of the comparing means. An image reading apparatus comprising correction means for correcting an image signal.
[0053]
<Embodiment 7> A reading process of reading an original at a predetermined reading position while conveying the original, reading a reference member every time the original is read, and a correction process of correcting a read image signal of the original read in the reading process In the image correction method of the image reading apparatus, the correction step corrects the read image signal based on a plurality of signal data obtained by reading the reference member a plurality of times with time in the reading step. An image correction method for an image reading apparatus.
[0054]
<Embodiment 8> A reference for irradiating a document using a light source, photoelectrically converting reflected light from the document to read information on the document, and correcting a read image signal obtained by reading the document A reading step of reading the first density reference member, and a plurality of signals obtained by reading a second density reference member different from the first density reference member a plurality of times in the reading step at a time. A comparison step for comparing, and a correction step for correcting the read image signal based on a first signal obtained by reading the first density reference member by the reading step and a comparison result of the comparison step. An image correction method for an image reading apparatus, comprising:
[0055]
<Ninth Embodiment> A control program for executing an image correction method of an image reading apparatus, which reads a document at a predetermined reading position while conveying the document, and reads a reference member every time the document is read; A correction step of correcting a read image signal of the original read in the reading step, wherein the correction step includes a plurality of signal data obtained by reading the reference member a plurality of times at a time by the reading step. A control program for correcting the read image signal based on the above.
[0056]
<Embodiment 10> A control program for executing an image correction method of an image reading apparatus, which irradiates a document using a light source, photoelectrically converts reflected light from the document, and reads information on the document And a reading step of reading a first density reference member serving as a reference for correcting a read image signal obtained by reading a document, and a second density reference member different from the first density reference member. A comparison step of comparing a plurality of signals obtained by reading a plurality of times at a time in the reading step; a first signal obtained by reading the first density reference member by the reading step; and the comparison step. And a correction step for correcting the read image signal based on the comparison result.
[0057]
【The invention's effect】
As described above, according to the image reading apparatus of the present invention, it is possible to appropriately prevent the deterioration of the image at the time of correcting the light amount fluctuation.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus according to an embodiment.
2 is a plan view of the image reading apparatus main body in FIG. 1. FIG.
FIG. 3 is a diagram showing a configuration in the vicinity of a CIS 110. FIG.
4 is a block diagram illustrating a configuration of a control system of the image reading apparatus in FIG. 1. FIG.
FIG. 5 is a block diagram illustrating a configuration of an image processing unit of the image reading apparatus according to the embodiment.
FIG. 6 is a flowchart illustrating a flow reading sequence of the image reading apparatus according to the embodiment.
FIG. 7 is a flowchart for setting a light amount variation correction value in the image reading apparatus according to the embodiment.
FIG. 8 is a diagram illustrating a sample region of a roller at the time of correcting a light amount variation.
FIG. 9 is a diagram illustrating a time-series read image at the time of flow reading of the image reading apparatus according to the embodiment.
FIG. 10 is a diagram illustrating a time-series read image at the time of flow reading of the image reading apparatus according to the embodiment.
[Explanation of symbols]
100 Image Reader 110 Contact Image Sensor (CIS)
113 Image sensor 121 Platen glass 122 Flow reading glass 124 Position sensor 125 Motor 126 Belt 127 White reference plate 200 Auto document feeder (ADF)
201 Platen roller 202 Paper feed roller 203 Transport roller 204 Transport roller 205 Paper feed tray 210 White sheet member

Claims (4)

A reading unit that reads a document at a reading position while conveying the document, a shading correction unit that performs a shading correction process on the document data read by the reading unit using a reference white plate, and a document reading position. and rollers for document conveyance was, in order to correct the surface obtained by change of light intensity reading light intensity variation data of said roller, and a gain correcting means for correcting the gain of original data shading correction process In the image reading device,
It said gain correcting means calculates a gain data on the basis of the weighted plurality of light intensity variation data read per a predetermined interval data, using the gain data, shading correction processed document data An image reading apparatus that corrects a gain. The image reading apparatus according to claim 1, wherein the determined interval is an interval at which the roller is read between documents . The gain correction means reduces the weighted specific gravity of the light amount variation data as it is temporally separated from the predetermined light amount variation data among the plurality of light amount variation data read at the determined intervals. The image reading apparatus according to claim 1. The image reading apparatus according to claim 1, wherein the gain correction unit includes a limiter unit that applies a limiter so that the gain data calculated by the gain correction unit falls within a specified change amount range.

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