JP2017092778A - Image reader, copying device, and reading method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in that warning or discontinuation during document reading requires a user to determine whether a read image is good or not, requiring a reading operation again as necessary, which is a burden on the user.SOLUTION: An image reader that optically reads an image on a document placed on a document platen performs processing described below. That is, while an image on a document plated on the document platen is read, the state of opening/closing of a document cover that covers/uncovers the document platen is detected and, on the basis of image data obtained by reading the document, the density of the background of the document is calculated. If it is determined through the detection that the document cover is opened during the reading of the document, the image data is corrected according to a change in the calculated density of the background of the document.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image reading apparatus, a copying apparatus, and a reading method thereof, and more particularly to, for example, an image reading apparatus, a copying apparatus, and a reading method for optically reading an image of a document.

  2. Description of the Related Art A conventional image reading apparatus (scanner apparatus) that optically reads an image of an original is provided with an openable and closable original cover that covers an original platen glass on which the original is placed. When the image reading apparatus reads an image of a document, the document cover is closed to fix the document, and a start button or the like is pressed to read the document image.

  Now, when the document cover is opened during image reading from the document, the light irradiating the document is transmitted through the document, so that the reflected light from the document is reduced and the image obtained by reading the document becomes dark. There is a possibility. In order to prevent this, for example, Patent Document 1 proposes a configuration in which a warning is notified to a user when an open state of a document cover is detected during image reading from a document.

  Further, Patent Document 2 proposes a configuration in which, when an open of the pressure plate is detected during image reading, the image reading is interrupted, image data acquired by reading is erased, and the carriage on which the reading sensor is mounted is returned to the initial position. ing.

JP 2007-300385 A Japanese Patent No. 4090011

  However, in the above conventional example, when the document cover is opened during document reading, the operability for the user is not necessarily good.

  The present invention has been made in view of the above conventional example, and provides an image reading apparatus, a copying apparatus, and a reading method thereof that can improve user operability even when a document cover is opened during document reading. The purpose is that.

  In order to achieve the above object, the image reading apparatus of the present invention has the following configuration.

  That is, a document cover that opens and closes with respect to the document table, a reading unit that reads an image of the document placed on the document table, a detection unit that detects an open / closed state of the document cover, and the reading Correction means for correcting image data read by the reading means after the detection when the detection means detects the open state of the original cover during reading of the original by the means. To do.

  According to another aspect of the present invention, the image reading apparatus having the above-described configuration and image data generated by reading an image of a document by the image reading apparatus or image data supplied from the outside are used. And a copying apparatus having an image forming apparatus for forming an image on a recording medium.

  According to another aspect of the present invention, there is provided a reading method of an image reading apparatus, which includes a reading step of reading an image of a document placed on a document table, and opening and closing of a document cover that opens and closes the document table. When an open state of the document cover is detected in the detection step during reading of the document in the reading step and the reading step, the image data read in the reading step is corrected after the detection. And a correction step.

  Therefore, according to the present invention, it is possible to perform high-quality image reading without bothering the user even when the document cover is opened during image reading of the document.

1 is a side sectional view showing a configuration of a copying apparatus that copies an image of a document as a typical embodiment of the present invention. FIG. 2 is a perspective view showing an overview of the copying apparatus shown in FIG. 1. FIG. 2 is a side cross-sectional view showing a structure along an original conveyance direction of an image reading apparatus provided in the copying apparatus shown in FIG. 1. FIG. 4 is a block diagram showing a control configuration of the copying apparatus 100 shown in FIGS. 1 to 3. It is a flowchart which shows the process of a density | concentration abnormality detection and correction | amendment by a pressure plate opening. It is a flowchart which shows the detail of a background density | concentration detection process.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to the case of forming significant information such as characters and graphics, but may be significant. Furthermore, it also represents a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or a medium is processed regardless of whether or not it is manifested so that a human can perceive it visually.

  The “recording medium” includes not only paper used in general recording apparatuses but also widely includes cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like.

<Outline of Copying Apparatus (FIGS. 1 to 4)>
FIG. 1 is a side sectional view showing a configuration of a copying apparatus that optically reads an image of an original and forms an image in accordance with an electrophotographic system, which is a typical embodiment of the present invention.

  As shown in FIG. 1, a copying apparatus 100 includes an apparatus main body 101, an image reading device (scanner) 103 provided on the upper portion of the apparatus main body 101, and an automatic document that can be opened and closed provided on the upper portion of the image reading apparatus 103. Supply device (ADF) 126.

  The automatic document feeder 126 separates recording media such as a sheet document D placed on the document placing table 106 one by one and supplies the separated recording medium to the image reading device 103. The image reading device 103 optically reads a sheet document D fed on a flow reading glass 109 by an automatic document feeder 126 by a line type image sensor unit (hereinafter, image sensor) 108. Further, the image reading apparatus 103 moves the image sensor 108 on the original table glass 107 such as a sheet original D or a book original from the left side to the right side (sub-scanning direction) of the drawing. Read optically. The main scanning direction is a direction orthogonal to the sub-scanning direction (a direction perpendicular to the paper surface), and corresponds to a direction (line direction) in which the reading elements of the image sensor 108 are arranged. The automatic document feeder 126 includes an ADF separation unit 115, a sheet discharge conveyance unit 116, a document discharge unit 117, a document pressing plate 118 that presses a book document, and a sheet document conveyance unit 121.

  The apparatus main body 101 can form an image on a sheet-like recording medium (for example, cut paper) based on image data obtained by reading an image on the recording medium with the image reading apparatus 103. The image reading apparatus 103 transfers image data generated by reading an image to an image forming apparatus 104 incorporated in the apparatus main body 101.

  The image forming apparatus 104 includes a printer engine that forms an image according to an electrophotographic method.

  FIG. 2 is a schematic perspective view of the copying apparatus 100 shown in FIG. The reference numerals given in FIG. 2 indicate the same components as those shown in FIG. Therefore, redundant description of the same components is omitted here.

  As shown in FIG. 2, the operation unit 105 includes a display unit, input keys, and the like, accepts the operation of the copying apparatus 100 by the user, and displays the state of the copying apparatus 100 and the progress of processing. Can do.

  Further, the automatic document feeder 126 can open and close the document table glass 107 by rotating in the direction of arrow A about the rotation shaft 102a. Further, arrow B indicates a direction corresponding to the above-described main scanning direction, but the document stopper pair 106a can slide in the direction of arrow B in accordance with the width of the image document in the direction of arrow B. Further, the document placement table 106 is provided with a document detection sensor 106b, and when a document is placed, the projection is pushed down, and the presence of the document can be transmitted to the copying apparatus 100. As can be seen from FIGS. 2 and 1, the document pressing plate (pressure plate) 118 is provided below the document cover 102.

  Returning to FIG. 1 and continuing the description, the apparatus main body 101 includes a laser driver unit 110, an image forming unit 111, and a cassette paper feeding unit 112. The image forming apparatus 104 includes a sheet discharge unit 113 configured to stack a plurality of sheets P, and the image forming apparatus 104 includes a cartridge cover unit 114 on a side surface. Further, the image reading apparatus 103 and the image forming apparatus 104 are joined by a joining portion 119.

  Further, the apparatus main body 101 includes a control unit 120 that realizes a facsimile function, a double-sided conveyance unit cover 122, a conveyance direction switching unit 123, and a resist conveyance unit 124. Further, the apparatus main body 101 includes an MP (multi-paper) paper feeding unit 125 and a double-sided conveyance unit 150 disposed inside the image forming apparatus 104.

  FIG. 3 is a side sectional view showing a structure along the document conveying direction of the image reading apparatus 103 provided in the copying apparatus 100 shown in FIG. 3 denote the same components as those shown in FIGS. 1 and 2. Therefore, redundant description of the same components is omitted here.

  As shown in FIG. 3, the sheet document conveying unit 121 is provided with a document feeding sensor 121h and a document edge sensor 121i. The document feeding sensor 121h detects whether or not the sheet document D has been fed out from the ADF separation unit 115 and the passage of the rear end of the sheet document D. The document edge sensor 121 i detects the passage of the leading edge and the trailing edge of the sheet document D. Detection signals from the document feeding sensor 121h and the document edge sensor 121i are used for timing control of image reading processing.

  The user places a document to be scanned on the document table 106. When the user instructs the start of image reading via the operation unit 105, the pickup roller 115a descends while rotating, and the separation roller 115b and the separation pad 115c separate the documents one by one and feed them to the inside. . The feed rollers 121a, 121b, and 121c convey the document to the reading position. When the document passes over the reading glass (platen glass) 109a positioned above the reading position, the image sensor 108 emits light from the lower side of the reading glass 109a, and the image sensor 108 receives the reflected light. Perform image reading.

  The paper discharge / reverse rollers 117a and 117b invert the original and convey it again to the original reading position via a flapper (not shown) when reading both sides of the original. The document whose image has been read is discharged to a paper discharge tray 117c. Sensors 115d for detecting the presence / absence of a recording medium (read original) in the conveyance path are appropriately disposed in the conveyance paths 121d and 121e. A reference white plate 109c is disposed on the reading glass 109a side.

  FIG. 4 is a block diagram showing a control configuration of the copying apparatus 100 shown in FIGS.

  In particular, FIG. 4 shows components related to image processing for processing image data obtained by reading an image of a document by the image reading device 103.

  The image sensor 108 of the image reading apparatus 103 is configured to read an image by the CIS method. However, the present invention is not limited to this, and an image sensor having a configuration to read an image by the CCD method may be used. good.

  The CPU 24 comprehensively controls the entire image reading apparatus 103 via a data bus and a system bus (hereinafter referred to as a bus) 10. The analog image signal output from the reading unit 40 of the image sensor 108 is amplified by an amplifier inside the reading unit 40 and converted into a digital signal by an A / D converter. The converted digital signal becomes image data expressing one pixel with 8 bits. In this case, the digital value expresses black as “0” and white as “255”, and becomes luminance data (density) in 256 levels from 0 to 255. This image data is stored in the image memory 51 via the bus 10.

  The image processing unit 41 performs correction processing on the image data stored in the image memory 51. The image data subjected to the correction processing by the image processing unit 41 is output to the image data generation unit 43 via the bus 10. The image data generation unit 43 edits the input image data into image data for each line in the main scanning direction, and generates image data for one page of the recording medium. Then, data for a necessary image size (document image area) is generated from the generated image data for one page. The image data generated by the image data generating unit 43 is output to the image forming unit 111 or transmitted to an external host device or the like via the communication interface (IF) 42 and reproduced (displayed) as an image. .

  The image detection unit 45 performs image feature detection processing such as edge detection on the image data stored in the image memory 51.

  The operation unit 105 of the image reading apparatus 103 displays the status of the image reading apparatus 103 and the operation status of the entire copying apparatus 100. In addition, the operation unit 105 receives an input of a reading command from the user. The open / close sensor 38 detects opening / closing of the automatic document feeder 126.

  In addition, a ROM 12 and a RAM 27 are connected to the bus 10. The ROM 12 stores a control program for realizing the operation described below, and the RAM 27 is used as a work area of the CPU 24, for example.

  Next, a description will be given of an image reading process executed by the copying apparatus having the above-described configuration, particularly the image reading apparatus. Hereinafter, correction processing for density abnormality of a read image caused by opening of the pressure plate will be described.

<Regarding the correction method for density abnormalities caused by opening the pressure plate>
FIG. 5 shows detection of density abnormality and image correction when the opening / closing of the ADF 126 is detected in a pressure plate scan mode in which the sheet document D placed on the platen glass 107 is optically read while moving the image sensor 108 in the sub-scanning direction. It is a flowchart which shows a process. Note that the processing shown in FIG. 5 is realized, for example, when the CPU 24 reads the control program stored in the ROM 12 into the RAM 27 and executes it.

  First, the user places the sheet document D on the document table glass 107, operates the operation unit 105, and presses the copy button. In response to this, a pressure plate scan by the image reading device 103 is started in step S101, and in step S102, the image sensor 108 is moved to the reference white plate 109c to read an image, and initial such as shading for adjusting the white reference level is performed. Execute the conversion process. When the adjustment processing of the image sensor 108 is completed in this way, in step S103, the image sensor 108 is moved to the reading start position (Sx) in the pressure plate scan mode, and an image for one line is read in the main scanning direction to read the image memory 51. To store. Thereafter, in steps S103 to S110, the image sensor 108 is repeatedly moved one pixel at a time in the sub-scanning direction until the image sensor 108 reaches the reading end position of the document, and an image is read line by line in the main scanning direction.

  That is, when an image for one line is read in the main scanning direction in step S103, the background density (Bg_x) of the image of the read line (x-th line) is detected in step S104. The background density detection method will be described later with reference to FIG. Further, in step S105, every time an image for one line is read in the main scanning direction, the open / close sensor 38 detects the open / closed state of the ADF 126 and checks whether it is open. If it is determined that the pressure plate open (that is, ADF open) has not been detected, the process proceeds to step S106, and the background density (Bg_x) is added to the “background density when the pressure plate is closed (Bg1)”, and the average is obtained. And updates the value (Bg1) ". Thereafter, the process proceeds to step S110.

  On the other hand, when it is determined that the pressure plate open (that is, ADF open) is detected, the process proceeds to step S107, and the detected background density (Bg_x) is added to “background density when the pressure plate is open (Bg2)”. Then, the value (Bg2) is updated by averaging. Thereafter, in step S108, the process checks whether the background density has changed as compared with the background density (Bg1) when the pressure plate is closed. As a result, if it is determined that the background density has changed (Bg1 ≠ Bg2), the process proceeds to step S109, and the density correction of the read image for one line in the main scanning direction is executed. In this density correction, the read image Lx of the x-th line in the sub-scanning direction is multiplied by the background density Bg1 when the pressure plate is closed, and the background density Bg2 when the pressure plate is open is divided to correct the image when the pressure plate is open. To do. Thereafter, the process proceeds to step S110. On the other hand, when it is determined that there is no change in the background density (Bg1 = Bg2), the process proceeds to step S110.

  In step S110, it is checked whether or not the image sensor 108 has reached the reading end position of the document. If not, the process proceeds to step S103, and if it has reached, the process ends.

<Details of background level detection processing>
Details of the background level detection processing (step S104 in FIG. 5) will be described here.

  FIG. 6 is a flowchart showing details of the background level detection process. In this embodiment, the background level detection process for acquiring the background color (the color of the recording medium) of the sheet document D when it is determined that the read image for one line in the main scanning direction is a character area. Execute. The image type determination may be executed by pre-scanning the document, or the user may input the image type from the operation unit 105. However, in any case, these type determinations are known. The description is omitted.

  The character image is exposed over a considerable portion of the color of the background of the recording medium. When the original is optically read, the reflection of the background is considerably reflected in the reflected light obtained by irradiating the original from the image sensor 108. Is reflected. Therefore, when the ADF 126 is opened, the contribution of the background portion is greatly reflected in the change in the reflected light. Therefore, the change in background density can be estimated from the image data obtained by reading the character image original.

  First, in step S301, the CPU 24 acquires a predetermined pixel (m) as a processing target area from the image data corresponding to the read image for one line in the main scanning direction.

  Next, in step S302, the CPU 24 checks whether or not the value (luminance value) of the pixel included in the target region is equal to or higher than the background level threshold (I (y) ≧ BgThr). Here, when it is determined that the value of the pixel included in the target region is equal to or greater than the background level threshold (I (y) ≧ BgThr), the process proceeds to step S303. On the other hand, if it is less than the background level threshold (I (y) <Bg) and it is determined that the pixel is a character, the process proceeds to step S304. That is, in step S302, it is determined whether each pixel is a character or a sheet original color for a predetermined pixel (m) region of the character image.

  In step S303, the pixel value is added to the cumulative pixel value in the image data corresponding to the image for one line and accumulated. Then, the number of pixels determined to be equal to or higher than the background level threshold value in step S302 is stored in the RAM 27 together with the cumulative value. Hereinafter, for the sake of explanation, the cumulative value is Sbg, and the number of pixels determined to be equal to or greater than the background level threshold is n.

  Next, in step S304, the CPU 24 checks whether calculation for a predetermined pixel (m) has been completed. If it is determined that the calculation has not been completed, the process advances to step S305 to advance the coordinate (y) of the target pixel by “1” along the main scanning direction. Thereafter, the process returns to step S302, and the processes from step S302 are repeated. On the other hand, when it is determined that the calculation for the predetermined pixel (m) has been completed, the process returns to step S306, and the CPU 24 divides the cumulative value (Sbg) by the number n of pixels to equal the number of pixels. By calculating the average value, the background color luminance value (background level) Bg of the sheet document D is acquired.

  Thereafter, the CPU 24 stores the luminance value (Bg) of the background color of the sheet document D in the RAM 27 and ends the background level calculation process.

  Therefore, according to the embodiment described above, even when the reflected light from the original decreases due to opening of the pressure plate during original reading and the read image becomes dark, the image data obtained by the original reading can be automatically corrected. . Accordingly, high-quality image reading can be realized without interrupting image reading, and user operability such as re-reading of a document can be improved.

  In the embodiment described above, the image reading in the normal pressure plate scan mode has been described. However, the present invention is not limited to this. For example, in the divided scan mode in which the image reading area is divided into a plurality of predetermined areas in the moving direction of the image sensor and scanned, the abnormal density of the read image may be detected and corrected for each divided area.

  In the above-described embodiments, the image density correction is executed to correct the image data when the reflected light is reduced due to the pressure plate opening and the read image becomes dark. It is not limited by. For example, when the color of the image changes due to the opening of the pressure plate, high-quality image data may be output while the image reading is continued by correcting the color. If the image is blurred, correction such as edge enhancement may be performed. Further, the image reading may be continued when the pressure plate is opened by performing other corrections.

  In the above-described embodiments, the copying apparatus in which the image reading apparatus (scanner apparatus) and the image forming apparatus (LBP) are integrated has been described as an example. However, the present invention is not limited thereto. The present invention may be, for example, a single-function scanner device that includes an ADF unit that automatically feeds recording paper to the image forming apparatus described above and an image reading device, or may be a multi-function device in which a facsimile function is added to a copying machine. good.

10 system bus, 12 ROM, 24 CPU, 27 RAM, 38 open / close sensor,
40 reading unit, 41 image processing unit, 42 communication IF, 43 image data generating unit,
45 image detection unit, 51 image memory, 105 operation unit, 111 image forming unit

Claims (13)

A document cover that opens and closes to the document table;
Reading means for reading an image of a document placed on the document table;
Detecting means for detecting an open / closed state of the document cover;
A correction unit that corrects image data read by the reading unit after the detection when the detection unit detects an open state of the document cover while the reading unit reads the document. A characteristic image reading apparatus.   The image reading apparatus according to claim 1, wherein the correction unit corrects an image density with respect to image data read by the reading unit after the open state of the document cover is detected. A calculation unit that calculates a background density of the document based on the image data acquired by the reading unit;
The correcting means is configured to apply an image to the image data after the open state of the original cover is detected based on the background density calculated by the calculating means before the open state of the original cover is detected. The image reading apparatus according to claim 1, wherein the density is corrected. The first background density of the document when the document cover is closed when the detection unit detects the open state of the document cover while the document is being read by the reading unit. And comparing means for comparing the second background density of the original when the original cover is in an open state,
The correction means, when there is a change in the first background density and the second background density from the comparison result of the comparison means, the image data after the open state of the document cover is detected. The image reading apparatus according to claim 3, wherein the image density is corrected with respect to the image. The reading unit reads an image of a document placed on the document table while moving in a first direction;
The calculating means includes
With respect to image data for each line acquired by a plurality of reading elements in which the reading unit is arranged in a second direction orthogonal to the first direction, a threshold value in which the value of the pixel is predetermined for each pixel First comparing means for comparing with,
Accumulating means for accumulating pixel values determined to be the background of the document based on a result of the comparison by the first comparing means;
The image reading apparatus according to claim 3, wherein the background density of the one line is calculated from an accumulated value accumulated over one line.   6. The image reading apparatus according to claim 5, wherein whether or not the document cover is opened is determined for the acquired image data for each line.   The image reading apparatus according to claim 5, wherein the background density of the document is calculated when the image of the document is a character image.   8. The calculation by the calculation unit and the correction by the correction unit are performed during reading of the document by the reading unit with respect to the entire reading area of the document table. The image reading apparatus according to item.   In the calculation by the calculation unit and the correction by the correction unit, the reading area of the document table is divided into a plurality of areas in the first direction, and the reading unit is reading the original for each of the divided areas. The image reading apparatus according to claim 5, wherein the image reading apparatus is performed as described above. A determination unit for determining that the document on the document table is not moved when the detection unit detects the open state of the document cover;
10. The correction unit according to claim 1, wherein the correction unit corrects the density of the image when the determination unit determines that the document on the document table is not moved. The image reading apparatus described.   11. The reading unit according to claim 1, wherein the reading unit continues reading the document on the document table when the detection unit detects the open state of the document cover. Image reading apparatus. An image reading apparatus according to any one of claims 1 to 11,
An image forming apparatus that forms an image on a recording medium based on image data generated by reading an image of a document by the image reading apparatus or image data supplied from the outside; apparatus. A reading method for an image reading apparatus, comprising:
A reading process of reading an image of a document placed on a document table;
A detection step of detecting an open / close state of a document cover that opens and closes with respect to the document table;
A correction step of correcting image data read in the reading step after the detection when the open state of the original cover is detected in the detection step during reading of the original in the reading step. Reading method.

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