JP2009267975A - Image reader and image-forming device for semiconductor integrated circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader and an image forming device for creating reference image data having higher precision as compared with before in the creation of reference image data for shading correction, and for preventing time for creating the reference image data from lengthening. <P>SOLUTION: The image-forming device adopts a means for equipping an operation section that calculates an average of hue in a plurality of pixels arranged in a vertical scanning direction from image data stored by a storage section to set a threshold based on the average, determines a pixel of which hue is lower than the threshold as an abnormal place in a shading reference plate, and excludes the pixel to generate the reference image data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading apparatus and an image forming apparatus.

  As is well known, an image reading apparatus provided in an image forming apparatus uses a line sensor to read a document image. In this line sensor, minute solid-state image sensors (semiconductor elements) such as CCDs (Charge Coupled Devices) corresponding to pixels are arranged in a straight line (line shape). In such a line sensor, there is usually a variation in light receiving sensitivity between a plurality of solid-state image sensors, a variation in the amount of transmitted light in the lens, and / or unevenness of an illumination light source or an optical system. Is subjected to shading correction for substantially correcting the above-described variation. In general, the shading correction is obtained by reading a shading reference plate having a reference white printed on the entire surface with a line sensor to obtain shading correction data, and using the shading correction data for image data of a document image read by the line sensor. Correction processing.

  However, if there is an abnormality such as a stain or a scratch on the shading reference plate, the dirty portion or the scratch portion is different from the reference white color, so that accurate shading correction data cannot be acquired. As a technique for solving such a problem, Patent Document 1 listed below discloses an average value, a minimum value, and a maximum value of image data when a part of a shading plate (corresponding to the shading reference plate) is read by a line sensor. It is disclosed that an abnormality of the shading plate is detected by calculating a value, and when the abnormality is detected, accurate shading correction data is acquired by reading other parts of the shading plate.

Further, in the cited reference 2 below, reference data is obtained by averaging the data for the first plurality of lines in the sub-scanning direction among the image data when the white reference plate (corresponding to the shading reference plate) is read. Compare the image data of the white reference plate that has been created and read after the creation of the reference data with the reference data, and if the difference between the two is large, the shading correction data (corresponding to the correction reference data) is to be created. Techniques to exclude are disclosed.
Japanese Patent Laid-Open No. 06-078147 JP 2002-300392 A

By the way, in the technique of the above-mentioned patent document 1, when an abnormality of the shading plate is detected by reading one part of the shading plate, the other part of the shading plate is read to obtain shading correction data. There is a problem that the creation time of the shading correction data becomes long.
In the technique of Patent Document 2, reference data is created based on a plurality of lines at the beginning of a white reference plate, and the reference data is used as a reference value to image data read from the white reference plate after the reference data is created. Judging whether there is a problem. However, if dust adheres to the white reference plate for creating the reference data, there is a problem in the image data after the creation of the reference data using the image data read from the white reference plate with the dust as reference data. Therefore, it cannot be said that highly accurate shading correction data excluding the influence of dust adhering to the white reference plate can be created.

  The present invention has been made in view of the circumstances described above, and in the creation of reference image data for shading correction, it is possible to create reference image data with higher accuracy than in the past, and the creation time of the reference image data is increased. An object of the present invention is to provide an image reading apparatus and an image forming apparatus that can prevent the above-described problem.

  In order to achieve the above object, according to the present invention, as a first solving means related to an image reading apparatus, in an image reading apparatus that performs shading correction based on reference image data obtained by reading an image on a shading reference plate, An image reading unit that reads the image of the shading reference plate while sequentially changing the reading position of the shading reference plate in the sub-scanning direction to generate image data, a storage unit that stores the image data, and image data that the storage unit stores And calculating a mean value of hues of a plurality of pixels arranged in the sub-scanning direction, setting a threshold based on the mean value, determining a pixel whose hue is lower than the threshold as an abnormal location on the shading reference plate, A means is provided that includes a calculation unit that excludes and generates the reference image data.

  In the present invention, as the second solving means related to the image reading apparatus, in the first solving means, the control unit adopts a means that uses a value obtained by subtracting 20% from the average value as the threshold value.

  In the present invention, as a third solving means relating to the image reading apparatus, in the first or second solving means, a shading reference roller is provided instead of the shading reference plate, and the shading reference roller rotates. The image reading unit employs means for reading the image of the shading reference roller while changing the reading position.

  In the present invention, as the first solving means relating to the image forming apparatus, means including any one of the first to third solving means relating to the image reading apparatus is employed.

According to the present invention, an average value of hues of a plurality of pixels arranged in the sub-scanning direction is calculated from image data, a threshold is set based on the average value, and pixels whose hue is lower than the threshold are abnormal on the shading reference plate. Since the reference image data for shading correction is generated excluding the corresponding pixel, it is not necessary to re-read the shading reference plate even if there is an abnormality in the shading reference plate, so the reference image data for shading correction It is possible to prevent the occurrence of the problem that the creation time of the file becomes long.
In addition, a threshold is set based on the average value of the hues of a plurality of pixels, pixels whose hue is lower than the threshold are determined as abnormal portions on the shading reference plate, and pixels that are lower than the threshold are excluded and a reference for shading correction is excluded. Since the image data is created, it is possible to reliably eliminate the influence of the shading reference plate abnormality such as dust adhering and to create reference image data with higher accuracy than before.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present embodiment relates to a multifunction peripheral that is one of image forming apparatuses.
FIG. 1 is a functional block diagram of a multifunction peripheral A according to the present embodiment. The multi-function device A includes a CPU (Central Processing Unit) 1, a ROM (Read Only Memory) 2, a RAM (Random Access Memory) 3, various sensor groups 4, a printing paper transport unit 5, an image data storage unit 6, and an image forming unit 7. A communication I / F unit 8, an operation display unit 9, and an image reading device 10.

  The CPU 1 is a control program stored in the ROM 2, detection signals input from the various sensor groups 4, image data stored in the image data storage unit 6, a personal computer or the like via the communication I / F unit 8. Based on a print instruction signal received from an external device, image data for printing, and an operation signal input from the operation display unit 9, the overall operation of the multifunction peripheral A is controlled.

The ROM 2 is a non-volatile memory that stores a control program executed by the CPU 1 and other data.
The RAM 3 is a working memory used as a temporary storage destination of data when the CPU 1 executes a control program and performs various operations.
The various sensor groups 4 are various sensors necessary for the image forming operation such as a paper out detection sensor, a paper position detection sensor, a temperature sensor, and the like, and output various information detected by each to the CPU 1 as detection signals.

The printing paper transport unit 5 transports printing paper stored in a printing paper tray (not shown) to the image forming unit 7, a motor for driving the printing paper transport roller, and printing paper after image forming processing. It comprises a transport roller for transporting to a printing paper discharge tray (not shown), a motor for driving the transport roller, and the like.
The image data storage unit 6 is, for example, a flash memory, and stores image data of a document in response to a request from the CPU 1 and outputs image data of a predetermined document to the CPU 1.

The image forming unit 7 is controlled by the CPU 1 based on the image data of the original document stored in the image data storage unit 6 and the image data for printing received from an external device such as a personal computer. The toner is transferred onto the conveyed printing paper, and the toner is fixed.
The communication I / F unit 8 is an interface for performing communication between the multifunction peripheral A and an external device such as a personal computer, and is connected to the external device via a network such as a LAN (Local Area Network).
The operation display unit 9 includes a start key, a stop key, a power key, a numeric keypad (numerical value input key), a touch panel, a clear key, and other various operation keys, and outputs an operation instruction for each key to the CPU 1. Under the control of the CPU 1, various screens are displayed on the touch panel.

Next, the image reading apparatus 10 will be described in detail with reference to FIG. FIG. 2 is a schematic configuration diagram illustrating a configuration of the image reading apparatus 10 of the multifunction peripheral A according to the present embodiment.
As shown in FIG. 2, the image reading apparatus 10 includes an automatic document feeder 11 and a flat bed reader 12. The automatic document feeder 11 automatically conveys the document placed on the document tray 11a. In addition to the document tray 11a, the CIS (Contact Image Sensor) 11b, the white reference roller 11c, the document discharge tray 11d, and the lamp 11e. And an image reading circuit 11f. The CIS 11b is an image reading unit in the present embodiment, and the white reference roller 11c is a shading reference roller in the present embodiment.

The document tray 11a is a table on which a document to be read is placed. The automatic document feeder 11 transports a document placed on the document tray 11a along a document transport path indicated by a dotted line by a plurality of transport rollers (not shown) and discharges the document onto a document discharge tray 11d.
The CIS 11b is a contact image sensor (line sensor) provided in the middle of the document transport path for reading an image on the back side of the document and for reading a front image of the white reference roller 11c. The CIS 11b outputs an image signal (analog signal) of an image read from the back side of the document or the white reference roller 11c to the image reading circuit 11f.

The white reference roller 11c is configured by a white rotating body and a motor that rotationally drives the rotating body, and is installed at a position facing the CIS 11b with the document conveyance path interposed therebetween. The white reference roller 11c is for providing reference image data used for shading correction. The document discharge tray 11d is a tray from which a document after reading conveyed by a conveyance roller (not shown) is discharged.
The lamp 11e irradiates the original or white reference roller 11c with illumination light (white light) having a constant intensity in a scanning manner. The CIS 11b converts the reflected light of the illumination light from the lamp 11e into an analog image signal.

The image reading circuit 11f will be described in detail with reference to FIG. FIG. 3 is a functional block diagram showing a functional configuration of the image reading circuit 11f. In FIG. 3, thick arrows indicate input / output of image signals and image data, and thin arrows indicate input / output of control signals.
The image reading circuit 11f controls the CIS 11b, the white reference roller 11c, and the lamp 11e, converts an image signal input from the CIS 11b into a digital signal (image data), and outputs the digital signal to the CPU 1 for A / D conversion. It comprises a section 13a, a reference image data storage memory 13b, an image processing circuit 13c, an image memory circuit 13d, an image reading RAM 13e, an image reading ROM 13f, and an image reading CPU 13g.

Under the control of the image reading CPU 13g, the A / D converter 13a converts the image signal (analog signal) of the image read by the CIS 11b from the back side of the document or the white reference roller 11c into image data (digital signal). The image data is output to the image processing circuit 13c or the image memory circuit 13d.
The reference image data storage memory 13b stores reference image data based on the image read by the CIS 11b from the white reference roller 11c under the control of the image reading CPU 13g.

Under the control of the image reading CPU 13g, the image processing circuit 13c is based on the reference image data stored in the reference image data storage memory 13b in the image data based on the image on the back side of the document input from the A / D conversion unit 13a. A shading correction process is performed and output to the image memory circuit 13d. Further, the image processing circuit 13c outputs the reference image data input from the image memory circuit 13d to the reference image data storage memory 13b.
The image memory circuit 13d stores image data input from the image processing circuit 13c or the A / D conversion unit 13a under the control of the image reading CPU 13g. Further, the image memory circuit 13d outputs the shading-corrected image data input from the image memory circuit 13d to the CPU 1.

The image reading RAM 13e is a working memory used as a temporary storage destination of data when the image reading CPU 13g executes a control program dedicated to the automatic document feeder 11 to perform various operations.
The image reading ROM 13f is a non-volatile memory that stores a control program executed by the image reading CPU 13g and other data.
The image reading CPU 13g controls the overall operation of the automatic document feeder 11 based on a control program dedicated to the automatic document feeder 11 stored in the image reading ROM 13f.

The flat bed reader 12 has a contact glass (not shown) as a document placement table fitted on the upper surface thereof, and reads the surface of the document placed on the contact glass along the document conveyance path. A mirror 12b, a condenser lens 12c, a CCD (Charge Coupled Devices) 12d, and an image reading circuit 12e are provided.
The lamp 12a irradiates the surface of the document on the contact glass with illumination light (white light) having a constant intensity in a scanning manner, and the mirror 12b reflects the reflected light from the surface of the document toward the condenser lens 12c. To do.

The condensing lens 12c condenses the reflected light of the surface of the document reflected by the mirror 12b on the light receiving surface of the CCD 12d. The CCD 12d converts the reflected light of the surface of the original collected by the condenser lens 12c into an image signal (analog signal) and outputs the image signal to the image reading circuit 12e.
The image reading circuit 12e performs image processing on the image data input from the CCD 12d, and outputs the image data generated by the image processing to the CPU 1.

  Next, the operation of the automatic document feeder 11 of the multifunction peripheral A according to the present embodiment configured as described above will be described with reference to FIGS. FIG. 4 is a flowchart showing the operation of the automatic document feeder 11, and FIG. 5 is a diagram showing an example of output values of image data based on an image read by the CIS 11b from the white reference roller 11c. FIG. 5 shows image data for 10 lines read from the white reference roller 11c by the CIS 11b line sensor including three sensor chips of 5 pixels. FIG. 6 is a graph of output values of the image data shown in FIG.

First, in the initial operation of the multi-function peripheral A when the power is turned on, the image reading CPU 13g causes the white reference roller 11c to rotate and causes the white reference roller 11c to irradiate the lamp 11e with illumination light. Then, the image reading CPU 13g causes the CSI 11b to receive reflected light for a plurality of lines in the sub-scanning direction of the white reference roller 11c and to sequentially convert the reflected light into an image signal. The image signal is converted into an A / D converter 13a. (Step S1).
The image reading CPU 13g causes the A / D converter 13a to convert the image signal, which is an analog signal, into image data, which is a digital signal, and outputs the image data to the image memory circuit 13d, and the image memory circuit 13d receives the image data. Store (step S2).

  When dust / dirt adheres to the white reference roller 11c, the output value of the pixel corresponding to the dust / dirt attachment location in the image data in step S2 is greater than the output value of the location where no dust / dirt adheres. Significantly smaller. In FIG. 5, the output values of lines 1 to 3 of the pixel 12 are the output values of the pixels corresponding to the dust / dirt adhering locations. The output values of lines 1 to 3 of the pixel 12 shown in FIG. 5 are significantly smaller than the output values of lines 4 to 10 of the pixel 12.

  5 are based on the image read by the sensor at the end of the sensor chip constituting the line sensor of the CIS 11b, and the end of the sensor chip is the sensor chip. Since the area of the light receiving surface is reduced by cutting in this processing, the output becomes smaller than other portions of the sensor chip. Therefore, only by comparing the output values of pixels on the same line (main scanning direction) of the image data, the output value of the pixels of the image data becomes small due to the influence of dust / dirt adhering to the white reference roller 11c. It is not possible to judge whether or not. Therefore, in this multifunction machine A, dust / dirt adheres to the white reference roller 11c by comparing the output values of the pixels in the sub-scanning direction, that is, by comparing the output values of the same pixels in each line of the image data. Judge that there is.

  The image reading CPU 13g calculates an average value of the output values for the pixels 1 to 15 based on the image data stored in the image memory circuit 13d in step S2, and a value obtained by multiplying the average value by 0.8, That is, a value obtained by subtracting 20% from this average value is calculated (step S3), and using this value as a threshold, it is determined whether or not the output values of the pixels 1 to 15 in each line of the image data are below this threshold ( Step S4).

  The image reading CPU 13g determines that dust / dirt is attached to the corresponding portion of the white reference roller 11c corresponding to the pixel of the image data that is less than the threshold value, and excludes the output value of the pixel for each of the pixels 1 to 15 Is calculated as a reference value (step S5), and the reference value for each pixel 1 to 15 is used as reference image data from the image memory circuit 13d to the reference image data storage memory 13b via the image processing circuit 13c. Store (step S6).

Step S5 will be specifically described with reference to FIGS. FIG. 7 shows an average value, threshold value, and reference value calculated by the image reading CPU 13g based on the output value of the image data shown in FIG. 5, and a line determined to have dust / dirt attached to each pixel of the image data. It is a figure which shows a number.
Since the output value of the pixels 12 of the lines 1 to 3 shown in FIG. 5 is smaller than the threshold value “116.1” of the pixel 12 shown in FIG. It is determined that dust / dirt is attached to the corresponding portion of the white reference roller 11c corresponding to the lines 1 to 3, and the output values of the lines 1 to 3 of the pixel 12 are excluded from the calculation of the reference value of the pixel 12. In step S5, the image reading CPU 13g calculates an average value of the output values of the lines 4 to 10 other than the lines 1 to 3 of the pixel 12, and uses the average value as the reference value of the pixel 12.

  As described above, in the MFP A according to the present embodiment, the image reading CPU 13g calculates the average value of 8-bit color values for each pixel 1 to 15 of the image data and minus 20% from the average value. The calculated value is set as a threshold, and the average value of the output values of the pixels 1 to 15 excluding the output values of the pixels below the threshold is calculated as a reference value. By using the reference value as the reference image data for shading correction, even if dust / dirt is attached to the white reference plate 11c, it is not necessary to read the white reference plate 11c again. Therefore, the reference image data for shading correction is used. It is possible to prevent the occurrence of the problem that the creation time of the file becomes long.

  Further, the image reading CPU 13g determines that dust / dirt is attached to the corresponding portion of the white reference roller 11c corresponding to the pixel of the image data below the threshold value, and the pixel 1 excluding the output value of the pixel Since the average value of the output values for each of 15 to 15 is calculated as a reference value, and the reference value for each pixel 1 to 15 is used as reference image data for shading correction, the influence of dust / dirt on the shading reference plate is ensured. It is possible to create highly accurate reference image data by eliminating.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, in order to create reference image data used for shading correction, the present invention in which image data is read from the white reference roller 11c is not limited to this.
The target for reading the image data may be a white reference plate having a plate shape instead of a white reference roller having a roller shape.

FIG. 2 is a functional block diagram of a multifunction peripheral A according to an embodiment of the present invention. 1 is a schematic configuration diagram illustrating a configuration of an image reading apparatus 10 of a multifunction peripheral A according to an embodiment of the present invention. 3 is a functional block diagram showing a functional configuration of an image reading circuit 11f of the multifunction peripheral A according to an embodiment of the present invention. FIG. 6 is a flowchart showing an operation of the automatic document feeder 11 of the multifunction peripheral A according to the embodiment of the present invention. It is a figure which shows an example of the output value of the image data based on the image which CIS11b of the multifunctional machine A which concerns on one Embodiment of this invention read from the white reference | standard roller 11c. It is a graph of the output value of the image data shown in FIG. 5 based on the image which CIS11b of the multifunctional machine A which concerns on one Embodiment of this invention read from the white reference | standard roller 11c. The average value, threshold value, and reference value calculated by the image reading CPU 13g of the multifunction peripheral A according to the embodiment of the present invention based on the output value of the image data shown in FIG. It is a figure which shows the number of lines judged to have adhered.

Explanation of symbols

  DESCRIPTION OF SYMBOLS A ... MFP, 1 ... CPU, 2 ... ROM, 3 ... RAM, 4 ... Various sensor groups, 5 ... Printing paper conveyance part, 6 ... Image data storage part, 7 ... Image formation part, 8 ... Communication I / F part , 9 ... Operation display section, 10 ... Image reading device, 11 ... Automatic document feeder, 11a ... Document tray, 11b ... CIS, 11c ... White reference roller, 11d ... Document discharge tray, 11e ... Lamp, 11f ... Image reading circuit , 12 ... Flat bed reader, 12a ... Lamp, 12b ... Mirror, 12c ... Condensing lens, 12d ... CCD, 12e ... Image reading circuit, 13a ... A / D converter, 13b ... Reference image data storage memory, 13c ... Image processing circuit, 13d ... Image memory circuit, 13e ... Image reading RAM, 13f ... Image reading ROM, 13g ... Image reading CPU

Claims (4)

In an image reading apparatus that performs shading correction based on reference image data obtained by reading an image of a shading reference plate,
An image reading unit that reads the image of the shading reference plate while sequentially changing the reading position of the shading reference plate in the sub-scanning direction, and generates image data;
A storage unit for storing the image data;
An average value of hues of a plurality of pixels arranged in the sub-scanning direction is calculated from the image data stored in the storage unit, and a threshold value is set based on the average value, and pixels whose hues are lower than the threshold value are abnormal in the shading reference plate A calculation unit that determines the location and excludes the pixel to generate the reference image data;
An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein the control unit sets a value obtained by subtracting 20% from the average value as the threshold value.   The shading reference roller is provided instead of the shading reference plate, and the image reading unit reads an image of the shading reference roller while changing a reading position by rotating the shading reference roller. Or the image reading apparatus of 2.   An image forming apparatus comprising the image reading apparatus according to claim 1.

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