JP2018101853A - Image reading device, control method therefor, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technoligy in which erroneous detection of a size of a document is prevented from occurring even when a foreign object exists on a document table in an image reading device which detects the size of the document by image reading.SOLUTION: An image reading device acquires image data by reading with an image sensor unit when operation for closing a document cover (document feeding unit) is started, and detects a size of a document and detects a foreign matter on a platen glass on the basis of the acquired image data (S202). The image reading device determines the size of the document on the platen glass on the basis of a detection result of the size of the document and a detection result of the foreign matter (S203 to S209).SELECTED DRAWING: Figure 5

Description

  The present invention relates to a technique for detecting the size of a document placed on a document table in an image reading apparatus.

  Among image reading apparatuses such as a copying machine, a facsimile apparatus, and a scanner apparatus, those having a function of automatically detecting the size of a document to be read are known. The size of the document is detected based on the obtained image data and the output from the document size detection sensor, for example, by placing the document on a document table (contact glass) and reading the image.

  Patent Documents 1 and 2 include an angle detection sensor for detecting an opening / closing angle, which is an angle formed by the pressure plate with respect to the document table, while the opening / closing angle of the pressure plate is in a range between the first angle and the second angle. Describes an image reading apparatus that detects an original size using an image sensor. In this image forming apparatus, after the pressure plate is opened, when the opening / closing angle of the pressure plate becomes equal to or smaller than the first angle (25 degrees), detection of the document size is started, and a second angle smaller than the first angle (for example, 5). The document size is fixed when it is below.

JP2012-39321A JP 2010-219667 A

  In the above-described prior art, the document size is detected while the pressure plate opening / closing angle is within a predetermined range. However, if the user's hand holding the document is in contact with the contact glass while the opening / closing angle of the pressure plate is within a predetermined range, the document size may be erroneously detected.

  SUMMARY An advantage of some aspects of the invention is that it provides a technique capable of more accurately detecting the size of a document.

  The present invention can be realized as an image reading apparatus, for example. An image reading and forming apparatus according to an aspect of the present invention includes a document table on which a document is placed, a document size detection unit that detects the size of a document placed on the document table, and a foreign material that detects foreign matter on the document table. A detection unit; and a determination unit that determines a size of the document on the document table based on a detection result of the document size detection unit and a detection result of the foreign object by the foreign object detection unit. To do.

  According to the present invention, the size of a document can be detected more accurately.

Sectional drawing which shows the structural example of an image reader and an image sensor unit Block diagram showing a control configuration example of an image reading apparatus The figure which shows the example of the relationship between the position where a document is placed on a platen glass, and the document size detected using an image sensor unit and a document size detection sensor The flowchart which shows the procedure of the process which detects and fixes the size of the original document placed on the platen glass in the image reading apparatus. A flowchart showing a procedure of document size detection processing in S106. The figure which shows the example of the luminance value contained in the image data output from an image sensor unit The figure which shows the example of a foreign material being detected within a document size detection area, and the example of the process which avoids a foreign material by movement of an image sensor unit

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, an image reading apparatus used in an image forming apparatus such as a copying machine or a multifunction peripheral (MFP) is used as an example. However, the following embodiments can be similarly applied to other apparatuses. The following embodiments do not limit the present invention according to the claims, and all combinations of features described in the present embodiments are not necessarily essential to the solution means of the present invention. .

<Image reading device>
First, a configuration example of the image reading apparatus 100 according to the present embodiment will be described with reference to FIG. 1A is a cross-sectional view illustrating a configuration example of the image reading apparatus 100, and FIG. 1B is a cross-sectional view illustrating a configuration example of the image sensor unit 50 provided in the image reading unit 110. The image reading apparatus 100 includes an image reading unit 110 that reads an image of a document, and a document feeding unit 120 that can feed and transport the document to the image reading unit 110.

  The image reading unit 110 includes an image sensor unit 50 for reading an original image, an original table glass 10 and a flow reading glass 20, a white reference plate 60, a drive motor 55, a guide shaft 56, and a drive belt 57. Prepare. The image sensor unit 50 is disposed below the document table glass 10 and the flow reading glass 20 while being fixed to the drive belt 57. The image sensor unit 50 can move in the direction of arrow H along the guide shaft 56 below the platen glass 10 and the flow reading glass 20 by transmitting the driving force of the driving motor 55 via the driving belt 57. It is. As the drive motor 55, a stepping motor, a DC motor, or the like is used.

  The document feeder 120 is supported on the image reading unit 110 by a support member (not shown) such as a hinge disposed on the back side in FIG. The document feeder 120 is supported by a support member so as to be rotatable about a rotation axis parallel to one side of the document table glass 10 on the back side in FIG. The document feeder 120 can be opened and closed with respect to the upper surfaces of the document table glass 10 and the flow reading glass 20 by such rotation.

(Image sensor unit 50)
As shown in FIG. 1B, the image sensor unit 50 includes light sources 51a and 51b, an optical lens 52, and a light receiving sensor 53. The light sources 51a and 51b are light sources such as LEDs that extend in a direction orthogonal to the document transport direction by the document feeder 120, and are used to irradiate the document with light. In this specification, the document transport direction (that is, the direction of the arrow H shown in FIG. 1A, which is the moving direction of the image sensor unit 50) is defined as the sub-scanning direction, and the direction orthogonal to this is defined as the sub-scanning direction. It is defined as the main scanning direction. The light receiving sensor 53 is an optical sensor composed of a plurality of light receiving elements (photoelectric conversion elements) arranged in a line in the main scanning direction for receiving reflected light of light irradiated on the original from the light sources 51a and 51b.

  Each of the light sources 51a and 51b is arranged so as to irradiate the original with light from a direction inclined by a predetermined angle with respect to the original table glass 10 (flow-reading glass 20). Light emitted from the light sources 51 a and 51 b and reflected from the lower surface of the document or the document feeder 120 is guided to a predetermined image formation position of the light receiving sensor 53 by the optical lens 52 and received by the light receiving sensor 53. The light receiving sensor 53 outputs an analog electrical signal corresponding to the amount of received light. As will be described later, based on a signal output from the light receiving sensor 53, image data corresponding to a document image to be read is generated as a result of reading the document image. In this way, the image sensor unit 50 reads the original image at an equal magnification for each line along the main scanning direction.

  Note that distortion (output error) occurs in the main scanning direction in the outputs of a plurality of light receiving elements arranged in the main scanning direction, which constitute the light receiving sensor 53. Therefore, in the image reading apparatus 100, in order to remove the distortion of the output of the light receiving sensor 53 before the reading of the document image is started, the result of reading the white reference plate 60 provided at the end of the document table glass 10 is used. Based on this, shading correction for correcting such distortion is performed. When the shading correction is performed, the light amount adjustment may be performed in order to make the light amount of the light emitted from the light sources 51a and 51b constant.

  Thus, the light sources 51a and 51b, the optical lens 52, and the light receiving sensor 53 constitute a line type image sensor that reads an image for each line. As shown in FIG. 1B, the image sensor unit 50 of the present embodiment employs a configuration that reads a document image by the CIS method, but a configuration that reads a document image by the CCD method. It may be adopted.

(Reading method)
As a method for reading a document image by the image reading unit 110, a “fixed reading method” in which an image of a document placed on the platen glass 10 is read by the user, and a document feeding unit 120 transports the document image onto the reading glass 20. There is a “flow-reading method” in which an image of a document to be read is read. The image reading apparatus 100 supports both a fixed reading method and a flow reading method.

(Fixed scanning image scanning)
When reading a document image using the fixed reading method, the document feeder 120 is opened by the user, the document is placed on the document glass 10 (on the document table), and the document feeder 120 is closed. As a result, the document is fixed on the platen glass 10. At this time, the image sensor unit 50 reads the document image through the document table glass 10 while moving in the sub-scanning direction below the document table glass 10.

(Scanning image scanning)
When reading a document image using the flow reading method, the document feeder 120 performs the following operation. A document D to be read by the flow reading method is placed on the document tray 30 by the user. The document D placed on the document tray 30 is fed by a paper feed roller 31 to a separation unit including a separation roller 32 and a separation plate 33. When a plurality of originals are fed by the paper feed roller 31, one original D is sequentially separated from the plurality of originals by the separation roller 32 and the separation plate 33 and conveyed.

  When the leading edge of the document D conveyed by the separation roller 32 is detected by the registration sensor S1, the rotation of the registration roller pair 34 is stopped. The skew of the document D is corrected when the leading edge of the document D hits the registration roller pair 34 whose rotation has stopped. The registration sensor S1 determines the skew correction timing of the document D, determines the timing of feeding the document D by the feed roller 31 based on the detection timing of the trailing edge of the document D, and determines the leading and trailing edges of the document D. It can be used to determine the size of the document D based on the detection timing.

  The document D whose skew has been corrected is conveyed to the reading position on the flow reading glass 20 through the conveyance path PS1. The document image is read by the image sensor unit 50 in accordance with the timing at which the document D transported on the transport path PS1 is detected by the read sensor S2. Prior to the start of reading the document image, the drive motor 55 is driven so that the image sensor unit 50 moves to a position below the flow reading glass 20 and stops. The document D that has passed through the position of the read sensor S2 is flown through the platen roller 35 and a pair of read rollers 36 and 37 disposed on the upstream side and the downstream side of the platen roller 35 in the conveyance direction of the document D, respectively. Carried over. When the document D is transported on the flow reading glass 20, the amount of lifting of the document D from the upper surface of the flow reading glass 20 is regulated by the platen roller 35. While the document D is being conveyed, the image of the document D is optically read by the image sensor unit 50 at the reading position on the flow reading glass 20.

  When only one side of the document D is read, the document D on which the image has been read is conveyed by the lead roller pair 37 toward the reverse discharge roller pair 38 and discharged to the document discharge unit 39. A discharge sensor S3 is disposed upstream of the reverse discharge roller pair 38 in the conveyance direction of the document D. Based on the timing when the end of the document D is detected by the discharge sensor S3, it can be determined whether or not the discharge of the document D to the document discharge unit 39 is completed.

  When both sides of the document D are read, the document D from which the image on the first surface is read by the image sensor unit 50 is transported to the reverse transport path PS2. More specifically, the reverse discharge roller pair 38 is stopped during the discharge of the original D, and then the original D is pulled back into the apparatus by reversely rotating the pair of rollers. Further, when the conveyance path is switched to the reverse conveyance path by the flapper 40, the document D is conveyed to the reverse conveyance path PS2 and sent again to the conveyance path PS1. As a result, the image sensor unit 50 reads the image on the second surface of the document D. The document D on which the image on the second surface has been read is discharged to the document discharge unit 39 by the read roller pair 37 and the reverse discharge roller pair 38. Note that jams such as a stay jam and a delay jam that can occur during document conveyance can be detected based on the timing at which the edge of the document D is detected by the registration sensor S1, the lead sensor S2, and the discharge sensor S3.

<Control Configuration of Image Reading Apparatus>
FIG. 2 is a block diagram illustrating a control configuration example of the image reading apparatus 100. FIG. 2 shows, among other things, components related to reading of an image of a document by the image reading apparatus 100 and processing of image data obtained by reading.

  The image reading apparatus 100 includes a CPU 24, a ROM 12, and a RAM 27. The CPU 24 controls the entire image reading apparatus 100 by controlling each device connected to the bus 21 including the system bus and the data bus. In addition to the CPU 24, ROM 12, and RAM 27, the bus 21 includes an image processing unit 41, a drive unit 44, an open / close detection unit 200, a document size detection sensor 70, an operation unit 105, a communication interface (I / F) 42, and image data. The generation unit 43 and the image sensor unit 50 are connected.

  The ROM 12 stores a control program for realizing the operation of the image reading apparatus 100 described below. The RAM 27 is a storage device (memory) used as a work area for the CPU 24 and used for storing various data such as image data. The CPU 24 implements various controls in the image reading apparatus 100 by reading the control program stored in the ROM 12 into the RAM 27 and executing it. The operation unit 105 includes a display unit (liquid crystal display or the like), receives a user operation, transmits operation information indicating the content of the user operation to the CPU 24, and operates an operation screen based on the screen information transmitted from the CPU 24. Is displayed on the display.

  In the image sensor unit 50, the analog electrical signal (analog image signal) output from the light receiving sensor 53 is amplified and converted into a digital signal by the amplifier / A / D converter 54 in the image sensor unit 50. Thereby, for example, image data (luminance data) in which one pixel is expressed by 8 bits is generated. In this case, the data of each pixel included in the image data can represent 256 levels of luminance (density) values from 0 to 255. For example, “0” represents black and “255” represents white. Image data generated by the image sensor unit 50 is stored in the RAM 27 via the image processing unit 41. The drive unit 44 performs drive control of the drive motor 55 in order to move the image sensor unit 50 in the sub-scanning direction (the direction of the arrow H shown in FIG. 1A).

  The image processing unit 41 can perform predetermined image processing on the image data generated by the image sensor unit 50. The image data generation unit 43 edits the input image data (luminance data) into image data for each line in the main scanning direction, and generates image data for one page of the recording medium. Further, the image data generation unit 43 can generate data of a necessary size area (original image area) from the generated image data for one page. The image data generated by the image data generation unit 43 is output to the image forming unit 111 or transmitted to an external host device or the like via the communication interface I / F 42. The image forming unit 111 forms an image on a sheet based on the input image data. Note that the sheet may be referred to as recording paper, recording material, recording medium, paper, transfer material, transfer paper, or the like.

  The angle detection sensors 201 and 202 are sensors for detecting an opening / closing angle that is an angle formed by the document feeder 120 with respect to the document table glass 10. The angle detection sensor 201 is a sensor for detecting a first angle (25 degrees in the present embodiment) among the opening and closing angles of the document feeder 120. The angle detection sensor 201 outputs a signal indicating OFF when the opening / closing angle exceeds the first angle, and ON when it is equal to or less than the first angle. The angle detection sensor 202 is a sensor for detecting a second angle (5 degrees in the present embodiment) smaller than the first angle among the opening and closing angles of the document feeder 120. The angle detection sensor 202 outputs a signal indicating OFF when the opening / closing angle exceeds the second angle, and ON when it is equal to or less than the second angle.

  The CPU 24 detects the opening / closing angle of the document feeder 120 based on the output signals of the angle detection sensors 201 and 202. Further, the CPU 24 determines the open / close state of the document feeder 120 with respect to the document table glass 10 based on the detection result of the open / close angle. Specifically, the CPU 24 determines that the document feeder 120 is open when the opening / closing angle of the document feeder 120 exceeds the first angle (25 degrees). When the opening / closing angle of the document feeder 120 is equal to or smaller than the first angle, the CPU 24 determines that the document feeder 120 has started to close. Further, when the opening / closing angle of the document feeder 120 is equal to or smaller than the second angle (5 degrees), the CPU 24 determines that the document feeder 120 is closed.

  The document size detection sensor 70 is an optical sensor used for detecting the size of the document placed on the document table glass 10 in the sub-scanning direction. As shown in FIG. 3, the document size detection sensor 70 is disposed in the area of the document table glass 10 and is disposed below the document table glass 10.

  In the present embodiment, the CPU 24 detects (determines) the size in the main scanning direction of the document placed on the document table glass 10 based on the image data (luminance data) output from the image sensor unit 50. Based on the detection result of the size of the original in the main scanning direction and the detection result of the original by the original size detection sensor 70, the CPU 24 determines which standard size (A3, A4, A4R, etc.) the original is. Determine. For example, the CPU 24 uses the image sensor unit 50 to determine that the size of the document in the main scanning direction is a size corresponding to A4 or A3, and when the document is not detected by the document size detection sensor 70. Determines that the document is an A4 document. The CPU 24 detects (determines) the size of the document in the sub-scanning direction based on such a determination result.

<Document size detection processing>
Next, a document size detection process performed when the image reading apparatus 100 reads a document by the fixed reading method will be described. In this case, the user opens the document feeding unit 120, places the document on the platen glass 10, closes the document feeding unit 120, and inputs an image reading execution instruction via the operation unit 105. At that time, it is assumed that the user presses the document by hand or places and puts something on the document so that the document on the platen glass 10 does not move. However, for example, when the user's hand holding the document is in contact with the platen glass 10, the image reading unit 110 may erroneously detect the size of the document placed on the platen glass 10.

  In the present embodiment, according to the procedure of the flowcharts shown in FIGS. 4 and 5, the document size is detected and determined so as to prevent the erroneous detection of the document size as described above, and the image can be read. FIG. 4 is a flowchart showing a procedure of processing for detecting and determining the size of the document placed on the platen glass 10 in the image reading apparatus 100. Each process shown in FIG. 4 is realized in the image reading apparatus by the CPU 24 reading the program stored in the ROM 12 into the RAM 27 and executing it.

  In order for the user to cause the image reading apparatus 100 to start reading a document by the fixed reading method, the user needs to open the document feeding unit 120 and place the document on the platen glass 10. Therefore, first, in S101, the CPU 24 determines whether or not the document cover is opened based on the output signals of the angle detection sensors 201 and 202. Here, the document cover is a pressing member for pressing the document placed on the document table glass 10 against the document table glass 10, and corresponds to the document feeder 120 in this embodiment. In an image reading apparatus that does not include the document feeder 120, a pressure plate may be used as the document cover.

  In S101, when the output signals of the angle detection sensors 201 and 202 indicate that the opening / closing angle of the document cover has changed from an angle equal to or less than the first angle (25 degrees) to an angle greater than the first angle, the CPU 24 displays the document cover. Is opened, and the process proceeds to S102. In other cases, the CPU 24 repeats the determination process of S101.

  In S102, the CPU 24 moves the image sensor unit 50 to a predetermined detection position (detection position 301 in FIG. 3). The detection position 301 is a default position of the image sensor unit 50 for detecting the size of the document placed on the platen glass 10. As will be described later, the CPU 24 moves the image sensor unit 50 from the default position when necessary, and detects the document size using the image sensor unit 50.

  In step S <b> 103, the CPU 24 uses the image sensor unit 50 to perform processing for detecting the presence or absence of a document placed on the document table glass 10. Specifically, the CPU 24 controls the image sensor unit 50 such that the light sources 51 a and 51 b are turned on and the reflected light of the light emitted from the light sources is received by the light receiving sensor 53. Thereby, the CPU 24 acquires image data for one line in the main scanning direction and stores it in the RAM 27 via the image processing unit 41. Furthermore, the CPU 24 detects the presence or absence of a document placed on the document table glass 10 based on the acquired image data. When the acquisition of the image data is completed, the CPU 24 controls the image sensor unit 50 so that the light sources 51a and 51b are turned off.

  For example, the CPU 24 determines that the luminance value of each pixel in the region in the main scanning direction where the document of any size shown in FIG. 3 is placed among the luminance values included in the acquired image data exceeds a predetermined threshold Th1. Check if it is. In S104, the CPU 24 determines that there is a document when the luminance value of each pixel in the area where the document of any size (for example, A5) is above the threshold Th1, advances the processing to S106, If not, it is determined that there is no document and the process proceeds to S105.

  In S105, the CPU 24 determines whether or not the document cover has started to close. Specifically, when the output signals of the angle detection sensors 201 and 202 indicate that the opening / closing angle of the document cover has become equal to or less than the first angle (25 degrees), the CPU 24 determines that the document cover has started to close, The process proceeds to S106. In other cases, the CPU 24 returns the process to S103, and performs the detection process of the presence / absence of a document again.

  In S106, the CPU 24 performs document size detection processing according to the procedure shown in the flowchart of FIG. First, in S201, the CPU 24 controls the image sensor unit 50 to turn on the light sources 51a and 51b. In step S <b> 202, the CPU 24 determines the main scanning direction of the document placed on the platen glass 10 based on the image data (luminance data) for one line in the main scanning direction output from the image sensor unit 50. The size in the sub-scanning direction is detected. Note that the size in the sub-scanning direction can be detected based on the detection result of the size of the document in the main scanning direction and the detection result of the document by the document size detection sensor 70 as described above.

  The CPU 24 detects the size of the document placed on the document table glass 10 in the main scanning direction for the document size detection area shown in FIG. FIG. 6 is a diagram illustrating an example of luminance values included in the image data output from the image sensor unit 50. FIG. 6A shows an example in which a foreign substance exists in an area other than the original area where the original exists in the original size detection area, and FIG. 6B shows an original in the original size detection area. An example in which no foreign matter exists in an area other than the document area is shown. In FIG. 6A, as shown in FIG. 7A, the user's hand holding the document D is in contact with the document table glass 10 in a region other than the document region, and such a user's hand is a foreign object. The example of the luminance value acquired when it exists as is shown.

  When the size of the document is detected based on the image data obtained by the image sensor unit 50, there is a possibility that a foreign object existing in an area other than the document area is erroneously detected as the document. For example, when the threshold value to be compared with the luminance value included in the image data is set to Th2 in FIG. 6 and a pixel having a luminance value exceeding the threshold value Th2 is detected as a document portion, the document size is erroneously detected. become.

  In the present embodiment, when the CPU 24 detects the document size based on the image data obtained by the image sensor unit 50, based on the image data, the CPU 24 detects within the detection region (document size detection region) in the main scanning direction. Detects existing foreign objects. Further, the CPU 24 determines whether or not to determine the detected document size for reading the document according to the foreign object detection result. For example, the CPU 24 does not determine the document size as long as a foreign object is detected in the detection area in the main scanning direction, and determines the document size when no foreign object is detected. Thus, the CPU 24 determines the size of the document on the document table glass 10 based on the document size detection result and the foreign object detection result. As a result, it is possible to prevent erroneous detection of the size of the document even if foreign matter exists on the document table glass 10.

  In the present embodiment, a luminance value range (foreign matter detection range) for detecting foreign matter existing in the document size detection region is predetermined. For example, the foreign object detection range is set to a range between the threshold values Th1 and Th2 shown in FIG. As will be described later, the CPU 24 determines whether or not the image data obtained by the image sensor unit 50 includes a luminance value within the foreign matter detection range, thereby detecting foreign matter existing in the document size detection area. I do. Further, the CPU 24 specifies an area including pixels having a luminance value within the foreign object detection range as a foreign object area, and specifies an area including pixels having a luminance value exceeding the range as an original area.

  Specifically, in S202, the CPU 24 compares the luminance value of each pixel of one line included in the image data obtained by the image sensor unit 50 with the threshold Th1, and has a luminance value exceeding the threshold Th1. Identify the pixel. Further, as shown in FIG. 6A, the CPU 24 specifies an area composed of pixels having a luminance value exceeding the threshold value Th1 as an original area, and sets the size (for example, the number of pixels) of the original area to the main scanning of the original. Identified as the size of the direction. At this time, the image sensor unit 50 is disposed at the default position 301 in the sub-scanning direction.

  In step S <b> 203, the CPU 24 detects a foreign substance by determining whether or not a foreign substance exists in the document size detection area based on the image data obtained by the image sensor unit 50. For example, as shown in FIG. 7A, the processing of S203 is performed when the user's hand holding the document D is in contact with the document table glass 10 in an area other than the document area. Is detected as a foreign object. Specifically, the CPU 24 determines that there is a foreign object when the image data obtained by the image sensor unit 50 includes a luminance value within the foreign object detection range (a range between Th1 and Th2). To do. Further, the CPU 24 identifies an area composed of pixels having such a luminance value as a foreign substance area where a foreign substance exists.

  In S203, the CPU 24 advances the process to S206 if a foreign object is detected based on the image data obtained by the image sensor unit 50, and advances the process to S204 if no foreign object is detected. When the process proceeds to S204, the CPU 24 waits for a predetermined time, and then determines whether or not the foreign object detection state in the document size detection area has changed in S205. Specifically, the CPU 24 acquires image data again by the image sensor unit 50, and detects a foreign object as described above. This is because, for example, a state in which an object other than the original is placed after the original is placed on the platen glass 10 (for example, a sheet or magazine is placed to press the original) is detected. It is a process performed. If a foreign object is detected as a result of this processing (ie, the foreign object detection state has changed), the CPU 24 advances the process to S206, and otherwise performs a document size detection process (S106). finish.

  In S206, the CPU 24 moves the image sensor unit 50 by a predetermined amount in the sub-scanning direction. As shown in FIG. 7B, this makes it possible to detect the document size while avoiding a foreign object (for example, a user's hand) existing on the document table glass 10. This is a process of moving from the default position 301. Thereafter, in S207, the CPU 24 acquires image data from the image sensor unit 50 again, and detects the size of the document placed on the document table glass 10 based on the acquired image data.

  Next, in S208, the CPU 24 determines whether or not the luminance value of the pixel in the specific area specified as the foreign substance area in S203 included in the image data obtained by the image sensor unit 50 is within the foreign substance detection range. judge. If the luminance value of the pixel in the specific area is still within the foreign object detection range, the CPU 24 returns the process to S206, and otherwise advances the process to S209. In S209, the CPU 24 determines whether or not the pixel value of the pixel in the specific area is below the threshold Th2 that is the lower limit of the foreign object detection range used in the determination in S208. If not, the process proceeds to S206. If it is lower, the document size detection process (S106) ends. As described above, the processes in S206 to S209 are repeated until no foreign object is detected in the specific area (as long as a foreign object is detected in the specific area). As a result of the processing in S206 to S209, as shown in FIG. 6B, no foreign matter is detected in the foreign matter region (specific region) where the foreign matter was detected in FIG. 6A. Therefore, it becomes possible to detect the document size more accurately.

  When the document size detection process in S106 is completed, the CPU 24 next determines whether or not the document cover is closed in S107. Specifically, when the output signals of the angle detection sensors 201 and 202 indicate that the opening / closing angle of the document cover has become equal to or smaller than the second angle (5 degrees), the CPU 24 determines that the document cover is closed, The process proceeds to S111. In other cases, the CPU 24 advances the processing to S108. In S108, the CPU 24 determines whether or not a timeout has occurred (a predetermined time has elapsed). If the timeout has occurred, the process proceeds to S111, and otherwise, the process proceeds to S109. In S109, the CPU 24 determines whether or not execution of a job for reading an image is started. If the execution of the job is started, the process proceeds to S111. Otherwise, the process proceeds to S110. . In S110, the CPU 24 waits for a predetermined time, and then returns the process to S103.

  In S111, the CPU 24 finally determines the document size detected in S202 or S207 so that it can be used for image reading. Thereafter, in S112, the CPU 24 controls the image sensor unit 50 so as to turn off the light sources 51a and 51b, and ends the process.

  As described above, according to the present embodiment, in the image reading apparatus 100 that detects the size of a document by reading an image, an erroneous detection of the size of the document occurs even if a foreign object exists on the platen glass 10. Can be prevented. Thus, it is possible to automatically determine the size of the detected document and execute image reading without requiring the user to specify the correct document size.

<Other embodiments>
The functions of the above embodiments can also be realized by the following configuration. That is, it is also achieved by supplying a program code for performing the processing of the present embodiment to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus executing the program code. In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code also realizes the function of the present embodiment.

  Further, the program code for realizing the function of the present embodiment may be executed by one computer (CPU, MPU), or may be executed by a plurality of computers cooperating. Also good. Further, the program code may be executed by a computer, or hardware such as a circuit for realizing the function of the program code may be provided. Alternatively, a part of the program code may be realized by hardware and the remaining part may be executed by a computer. Further, the CPU is not limited to the one that performs all the processing by one CPU, and a plurality of CPUs may perform the processing while appropriately cooperating.

  In the above embodiment, the document size is detected based on the reading result by the image sensor unit 50. However, the document size detection sensor is provided separately from the document image reading sensor. May be. Also with this configuration, by using the embodiment described above, it is possible to prevent erroneous detection of the size of the document even if foreign matter is present on the platen glass 10.

100: Image reading device, 10: Document glass, 12: ROM, 24: CPU, 27: RAM, 41: Image processing unit, 42: Communication I / F, 43: Image data generation unit, 50: Image sensor unit, 70: Document size detection sensor, 105: Operation unit, 110: Image reading unit, 111: Image forming unit, 120: Document feeding unit, 201, 202: Angle detection sensor

Claims (11)

A platen on which the document is placed;
Document size detection means for detecting the size of the document placed on the document table;
Foreign matter detection means for detecting foreign matter on the document table;
Determination means for determining the size of the document on the document table based on the detection result of the document size detection means and the detection result of the foreign matter by the foreign matter detection means;
An image reading apparatus comprising: Further comprising reading means for reading an image of a document placed on the document table;
The document size detection means detects the size of the document on the document table from the reading result of the reading means,
2. The image according to claim 1, wherein the determination unit determines a document size based on a reading result acquired by the reading unit, and determines a document size when no foreign matter is detected by the foreign matter detection unit. Reader. The reading unit acquires image data for one line in the first direction,
The foreign object detection means detects the foreign object by determining whether or not the luminance value of each pixel included in the image data is a luminance value within a predetermined range,
The image reading apparatus according to claim 2, wherein the determination unit determines the document size in the first direction based on the image data acquired by the reading unit. Further comprising control means for controlling the reading means to be movable in a second direction orthogonal to the first direction,
The control means moves the reading means in the second direction when the foreign matter is detected by the foreign matter detection means,
The image reading apparatus according to claim 3, wherein the determination unit determines the document size based on a reading result of the reading unit moved by the control unit. The control means moves the reading means until no foreign matter is detected by the foreign matter detection means, and determines the document size determined by the determination means at a position where no foreign matter is detected by the foreign matter detection means. The image reading apparatus according to claim 4. The determination unit determines, as the document size, a size of an area composed of pixels having a luminance value exceeding a first threshold among luminance values included in the image data,
The foreign object detection means determines an area composed of pixels having a luminance value within a range between the first threshold value and a second threshold value smaller than the first threshold value as an area where the foreign object exists. The image reading apparatus according to claim 3. A document cover that can be opened and closed with respect to the document table;
An angle detection sensor for detecting an opening / closing angle that is an angle formed by the document cover with respect to the document table;
The determination unit is configured to determine the document size when the angle detection sensor detects that the open / close angle changes from the first angle to the first angle or less. The image reading apparatus according to any one of 2 to 6. The determination unit is configured such that when the foreign object detection unit does not detect the foreign object and the angle detection sensor detects that the opening / closing angle is equal to or smaller than a second angle smaller than the first angle, The image reading apparatus according to claim 7, wherein the detected document size is determined. The reading unit includes a light source and a plurality of light receiving elements arranged in a line in a first direction for receiving reflected light of the light emitted from the light source, and is output from the plurality of light receiving elements. The image reading apparatus according to claim 2, wherein the signal is generated as image data for one line. A method for controlling an image reading apparatus including a document table on which a document is placed,
A document size detecting step of detecting a size of a document placed on the document table;
A foreign matter detection step of detecting foreign matter on the platen;
A determination step of determining the size of the document on the document table based on the detection result in the document size detection step and the detection result of the foreign matter in the foreign matter detection step;
A control method for an image reading apparatus.   The program for making a computer perform each process of the control method of the image reading apparatus of Claim 10.

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