JP5162205B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus capable of reading both sides of a document, and an image forming apparatus including the image reading apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a facsimile, the front and back surfaces of a document are automatically read by an image reading device provided with an automatic document feeder (ADF). In this document reading, a method is widely employed in which an image sensor reads an image on the front side of a document, then reverses the front and back sides of the document, and the image sensor reads the image on the back side of the document again.

In Patent Document 1, reading of one surface of a document is performed by a reduction optical system image sensor provided on the apparatus main body side, and reading of the other surface of the document is performed by close contact provided on the automatic document feeder. Double-sided simultaneous reading mode that scans both sides of the document almost simultaneously with one document transport (one pass) without inverting the document, and inverting the document read by the reduction optical system image sensor. An apparatus capable of setting either of the double-sided reverse reading mode for reading by an optical image sensor is disclosed.
JP 2004-15299 A

  However, in the apparatus described in Patent Document 1, when dust adheres to the contact optical system image sensor, no measures are taken, so black streaks appear in the read image data, and the read image The problem that the image quality of data deteriorates occurs.

  An object of the present invention is to provide an image reading apparatus and an image forming apparatus that can read image data without deteriorating image quality when dust adheres to a contact optical system image sensor.

An image reading apparatus according to claim 1 is conveyed by a document feeding unit that conveys a document, a first reading unit that reads one side of a document conveyed by the document feeding unit, and the document feeding unit. After the reading of one side of the document by the second reading unit that reads the other side of the document and the first reading unit, the document is reversed so that the other side is read by the first reading unit. And a reversing unit that conveys the original and the first reading unit reads one side of the original, and after the original is reversed by the reversing unit, the first reading unit reads the other side of the original. Mode and double-sided simultaneous reading mode in which the first reading unit reads one side of the original and the second reading unit reads the other side of the original in one original conveyance by the original feeding unit. In either mode A mode setting unit for detecting dust adhering to the second reading unit, and the mode setting unit is a case where dust adhering is detected by the dust detecting unit, If the size of the dust that is is larger Ri by predetermined size, it said without setting the dual-side scanning mode is set to the duplex copy reading mode, the dust detection unit, by the mode setting unit When the double-sided simultaneous reading mode is set, during the continuous reading of the document, a process for detecting adhesion of dust is executed every time each document is read by the second reading unit, and the mode setting unit When the dust detection is detected by the detection unit and the size of the detected dust is larger than a predetermined size, the double-sided simultaneous reading mode is canceled and the double-sided reverse reading mode is set. Constant, and the rest of the document to read in the duplex copy reading mode, said mode setting section, to read the white roller disposed to face the first reading unit to the first reading section, obtained The image data is added to each pixel constituting the first reading unit arranged in one line in the main scanning direction, and a pixel whose added value exceeds a certain level is detected. If it is present continuously, it is determined that the size of the detected dust is larger than a predetermined size, the first reading unit is constituted by a reduction optical system image sensor, and the second reading unit is closely contacted A process comprising an optical image sensor, wherein the first reading unit reads a document at a predetermined document reading position, and the dust detection unit detects whether dust is present at the document reading position. Run further and before When the dust detection unit detects the presence of dust at the document reading position, the dust detection unit further includes a position setting unit that sets the document reading position to a position where dust does not exist, and the position setting unit includes the document reading position. The position is moved by a predetermined distance in the sub-scanning direction, and the dust detection unit is caused to execute again the process of detecting whether dust is present at the document reading position, and the process is repeated to repeat the process. Is set .

According to this configuration, when it is detected that dust is attached to the second reading unit, the double-sided reverse reading mode for reading a document without using the second reading unit without setting the double-sided simultaneous reading mode. Therefore, even when dust is attached to the second reading unit, the image is read without being deteriorated as a result of the original being read by the first reading unit, not the second reading unit having dust attached. Data can be read. Note that dust includes dirt and dirt.
Further, according to this configuration, during the continuous reading of the document, each time each document is read by the second reading unit, the process for detecting the attachment of dust is executed, and the dust attached to the second reading unit is detected. Since the original to be read thereafter is read in the double-sided reverse reading mode, the image data can be read without degrading the image quality when dust adheres to the second reading unit during the continuous reading.
Further, according to this configuration, since the first reading unit used for reading both sides of the document is a reduction optical system image sensor, if both sides of the document are read by the first reading unit by reversing the front and back, both sides of the document are read. A color image can be read with high quality without causing a difference in color of the image. Furthermore, since the second reading unit that reads the other side of the document is a contact optical system image sensor, the second reading unit does not require a large space as in the case where the reduction optical system image sensor is provided, and it is a relatively small space. Can be arranged.
Further, according to this configuration, when dust is attached to the document reading position, the document reading position is set to a different position where dust does not exist, so that image data can be read without degrading image quality. .

  The image reading apparatus according to claim 2 is characterized in that the double-sided simultaneous reading mode is prohibited when the dust detection unit detects adhesion of dust.

  According to this configuration, when the adhesion of dust is detected, the double-sided simultaneous reading mode is prohibited, so that it is possible to prevent a low-quality image from being output.

The image reading apparatus according to claim 3 further includes an image processing unit, and the mode setting unit detects the size of the detected dust smaller than a predetermined size even when the dust is detected by the dust detection unit. In this case, the image processing unit is caused to perform image processing for reducing deterioration in image quality due to dust in image data of a document read by the second reading unit without canceling the setting of the double-sided simultaneous reading mode. To do.

  According to this configuration, even when dust adhering to the second reading unit is detected, if the size of the dust is small, the document is read in the double-sided simultaneous reading mode, and the obtained image data Since the appearing dust is removed by image processing, the double-sided simultaneous reading mode capable of high-speed reading is continuously set, so that double-sided reading can be performed at high speed.

According to a fourth aspect of the present invention, there is provided an image forming apparatus that records an image on the basis of the image reading apparatus according to any one of the first to third aspects and read image data read by the first reading unit and the second reading unit. And an image forming unit to be formed.

  According to the present invention, even if dust adheres to the second reading unit including the contact optical system image sensor, the document is read by the first reading unit, not the second reading unit on which dust is attached. Image data can be read without degrading the image quality.

(Embodiment 1)
Hereinafter, an image reading apparatus and an image forming apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. In the following embodiment, an example in which the image reading apparatus and the image forming apparatus according to the present invention are integrated into a multifunction machine having functions such as a color copy, a scanner, a facsimile, and a printer will be described.

  FIG. 1 is a longitudinal sectional view schematically showing an internal configuration of the multifunction machine 1 according to the first embodiment. The multifunction device 1 is roughly composed of an image reading device 2 and a device body 3. The image reading apparatus 2 includes a document feeding unit 21 (see FIG. 3), a scanner unit 23 (see FIG. 3), a CIS 231, an operation unit 5, and a reversing mechanism and control unit 61 to be described later (see FIG. 3). And comprising. The document feeder 21 includes an ADF (Automatic Document Feeder), and includes a document tray 211, a pickup roller 212, a transport drum 213, a paper discharge roller 214, and a paper discharge tray 215. A document to be read is placed on the document tray 211. Documents placed on the document tray 211 are taken one by one by the pickup roller 212 and conveyed to the conveyance drum 213. The document that has passed through the transport drum 213 is discharged to a discharge tray 215 by a discharge roller 214.

  The scanner unit (first reading unit) 23 optically reads an image of a document and generates image data. The scanner unit 23 includes a platen glass 221, a light source 222, a first mirror 223, a second mirror 224, a third mirror 225, a first carriage 226, a second carriage 227, an imaging lens 228, and a CCD (Charge Coupled Device) 229. Prepare. In the scanner unit 23, a white fluorescent lamp such as a cold cathode fluorescent tube is used as the light source 222, and the first mirror 223, the second mirror 224, the third mirror 225, the first carriage 226, the second carriage 227, and the imaging. A lens 228 guides light from the document to the CCD 229. Since the scanner unit 23 uses a white fluorescent lamp such as a cold cathode fluorescent tube as the light source 222, it is superior in color reproducibility to the CIS 231 described later in which a three-color LED or the like is used as the light source.

  A document is manually placed on the platen glass 221 by a user's manual operation when reading the document without using the document feeder 21. The light source 222 and the first mirror 223 are supported by the first carriage 226, and the second mirror 224 and the third mirror 225 are supported by the second carriage 227.

  As a document reading method of the image reading apparatus 2, the scanner unit 23 reads a document placed on the platen glass 221, and the document is loaded by the document feeding unit 21 (ADF). There is an ADF reading mode for reading a document. In the flatbed reading mode, the light source 222 irradiates a document placed on the platen glass 221, and reflected light for one main scanning line is reflected in the order of the first mirror 223, the second mirror 224, and the third mirror 225. Then, the light enters the imaging lens 228. The light incident on the imaging lens 228 is imaged on the light receiving surface of the CCD 229. The CCD 229 is a one-dimensional image sensor, and simultaneously processes a document image for one line. The first carriage 226 and the second carriage 227 are configured to be movable in a direction orthogonal to the main scanning direction (sub-scanning direction, arrow Y direction). The first carriage 226 and the second carriage 227 move in the orthogonal direction, and the next line is read.

  In the ADF reading mode, the document feeder 21 takes in the documents placed on the document tray 211 one by one by the pickup roller 212. At this time, the first carriage 226 and the second carriage 227 are disposed below the reading window 230. When the document is transported by the document feeder 21, when the document passes over the reading window 230 provided in the transport path from the transport drum 213 to the paper discharge tray 215, the light source 222 irradiates the document and corresponds to one main scanning line. The reflected light is reflected in the order of the first mirror 223, the second mirror 224, and the third mirror 225 and enters the imaging lens 228. The light incident on the imaging lens 228 is imaged on the light receiving surface of the CCD 229. Subsequently, the document is conveyed by the document feeder 21 and the next line is read.

  Further, the document feeder 21 has a reversing mechanism (reversing unit) including a switching guide 216, a reversing roller 217, and a reversing conveyance path 218. The reversing mechanism reverses the front and back of the original whose front side (one side of the original) has been read by the first ADF reading and transports it again to the reading window 230, so that the back side (the other side of the original) is re-charged by the CCD 229. Is read. This reversing mechanism operates only when reading both sides and does not operate when reading one side. After reading the back side during single-sided reading and double-sided reading, the switching guide 216 is switched to the upper side, and the document that has passed through the transport drum 213 is discharged to the discharge tray 215 by the discharge roller 214. After the surface reading at the time of double-sided reading, the switching guide 216 is switched to the lower side, and the document that has passed through the transport drum 213 is transported to the reverse transport path 218 by the reverse roller 217. Thereafter, the switching guide 216 is switched to the upper side, the reverse roller 217 rotates in the reverse direction, and the original is fed again to the transport drum 213. Hereinafter, a mode in which both sides of a document are read using a reversing mechanism is referred to as a double-sided reversal reading mode or a high image quality mode.

  Further, in the ADF reading mode, the image reading apparatus 2 according to the present embodiment causes the CCD 229 to read the surface of the document while the document is being conveyed as described above, and at the same time, the CIS (second reading unit) 231. Can read the back side of the document. In this case, the surface of the document conveyed from the document tray 211 by the document feeder 21 is read by the CCD 229 when passing through the reading window 230, and the back surface is read when passing through the location where the CIS 231 is arranged. In CIS231, RGB three-color LEDs or the like are used as light sources. By using the CCD 229 and the CIS 231 in this way, it is possible to read both the front and back sides of a document by a single document transport operation (one pass) from the document tray 211 to the paper discharge tray 215 by the document feeder 21. Hereinafter, a mode in which both sides of the document are read using the CCD 229 and the CIS 231 in this way is referred to as a double-sided simultaneous reading mode or a high-speed mode.

  Here, the high image quality mode (double-sided reverse reading mode) and the high-speed mode (double-sided simultaneous reading mode) will be described. In the high image quality mode, both sides of the original are read by the same image sensor (CCD 229). Therefore, even if duplex printing is performed based on the acquired image data, there is no difference in the image quality of the printed images on both sides. However, in the high-speed mode, reading is performed by different image sensors such as the CCD 229 on the front side and the CIS 231 on the back side. Therefore, particularly in the case of a color original, if duplex printing is performed based on the image data acquired by each image sensor, There is a difference in the image quality of the printed images. This is because the CCD 229 is configured as an image sensor in which a plurality of light receiving elements are formed on a single chip in addition to the above-described difference in spectral distribution of the light source used when reading the original by the CCD 229 and the CIS 231. In CIS231, since a plurality of solid-state image sensors are connected to form an image sensor, sensitivity variation occurs between the solid-state image sensors, which is considered to cause a difference in image quality.

  Therefore, in the multi-function device 1 of the present embodiment, in order to solve the above-described difference in image quality, when performing double-sided reading of an original using the ADF reading mode, the user can use the high-quality mode (double-sided reverse reading mode) or high-speed. One of the modes (double-sided simultaneous reading mode) can be selected. In other words, high-quality mode (double-sided reverse reading mode) is used to match the image quality of double-sided printed images, and high-speed mode (priority is given to shortening the reading time even if there is a difference in image quality of double-sided printed images) The user can select a mode according to the situation, for example, “double-sided simultaneous reading mode”.

  Further, the multifunction machine 1 includes an apparatus main body 3 and a stack tray 6 disposed on the left side of the apparatus main body 3. The apparatus main body 3 includes a plurality of paper feed cassettes 461, a paper feed roller 462 that feeds recording paper from the paper feed cassette 461 one by one and transports it to the recording unit 40, and a recording paper transported from the paper feed cassette 461. And a recording unit 40 for forming an image.

  The recording unit 40 is based on a charge eliminating device 421 that removes residual charges from the surface of the photosensitive drum 43, a charging device 422 that charges the surface of the photosensitive drum 43 after charge removal, and image data acquired by the scanner unit 23. The laser beam is output to expose the surface of the photosensitive drum 43, and an exposure device 423 for forming an electrostatic latent image on the surface of the photosensitive drum 43, and on the photosensitive drum 43 based on the electrostatic latent image. , Cyan (C), magenta (M), yellow (Y), and black (K) toner images of respective colors formed on the photosensitive drum 43 and developing devices 44K, 44Y, 44M, and 44C that form toner images of the respective colors. The transfer drum 49 on which the image is transferred and superimposed, the transfer device 41 that transfers the toner image on the transfer drum 49 to the paper, and the paper on which the toner image has been transferred are heated to transfer the toner image to the paper And a fixing device 45 for fixing. Note that toner is supplied to each color of cyan, magenta, yellow, and black from a toner supply container (toner cartridge) (not shown). In addition, conveyance rollers 463 and 464 that convey the recording paper that has passed through the recording unit 40 to the stack tray 6 or the discharge tray 48 are provided.

  When forming images on both sides of the recording paper, the recording unit 40 forms an image on the surface of the recording paper, and then the recording paper is nipped by the conveyance roller 463 on the discharge tray 48 side. In this state, the conveyance roller 463 is reversed to switch the recording paper, the recording paper is sent to the paper conveyance path L and conveyed again to the upstream area of the recording unit 40, and an image is formed on the back surface by the recording unit 40. The recording paper is discharged to the stack tray 6 or the discharge tray 48.

  Further, in front of the apparatus main body 3, an operation unit 5 having a display unit through which a user can visually recognize an operation screen and various messages, and operation buttons for inputting various operation commands is provided. FIG. 2 is an example of a front view of the operation unit 5. The operation unit 5 includes a display unit 51, a touch panel 52, a numeric key group 53, various operation buttons 54 to 57, a function selection button 58, and the like. The display unit 51 is configured by an LCD (Liquid Crystal Display), an ELD (Electronic Luminescent Display), or the like, and displays an operation guidance screen for the user such as paper size selection, magnification selection, density selection, and the like. The display unit 51 is formed integrally with the touch panel 52. The touch panel 52 detects a touch position and outputs a detection signal to a control unit described later when a touch operation is performed by the user.

  The numeric key group 53 is for inputting, for example, the number of copies when operating the copy function of the multifunction machine 1 and the telephone number of the transmission destination when operating the facsimile function. The power saving button 54 is a button for setting the multifunction machine 1 in a power saving (low power) mode. The start button 55 is a button for starting a copy operation or a scanner operation, and the stop / clear button 56 is a button for stopping the copy operation or the scanner operation or canceling an input operation. The reset button 57 is a button for setting the display of the display unit 51 and various settings to an initial state or a standard operation state. The function selection button 58 is a button for setting a copy function, a printer function, a scanner function, and a facsimile function.

  FIG. 3 is a block diagram showing an electrical configuration of the multifunction machine 1. The same parts as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted. The multifunction device 1 includes a control unit 61, a document feeding unit 21, a scanner unit 23, a CIS 231, an operation unit 5, an image processing unit 64, a recording unit 40, and a communication unit 66.

  The control unit 61 controls the overall operation of the multifunction machine 1 and is configured by a CPU or the like. The document feeding unit 21, the scanner unit 23, the CIS 231, the operation unit 5, the image processing unit 64, the recording unit 40, and the communication unit 66 operate under the control of the control unit 61. The control unit 61 executes processing based on an operation control program stored in an unillustrated ROM or HDD in accordance with various instruction signals input to the operation unit 5 from the user, The multifunction device 1 is comprehensively controlled by outputting an instruction signal, transferring data, and the like.

  The control unit 61 includes a mode setting unit 611 and a dust detection unit 612. The mode setting unit 611 sets the multifunction device 1 to the double-sided reverse reading mode or the double-sided simultaneous reading mode according to the operation input of the operation unit 5 by the user. The control unit 61 operates the required units in the mode set by the mode setting unit 611.

  Here, the double-sided reverse reading mode is a mode in which the scanner unit 23 reads the front surface of the document and the scanner unit 23 reads the back surface of the document after the document is reversed by the reversing mechanism. The double-sided simultaneous reading mode is a mode in which the scanner unit 23 reads the front side of the original and the CIS 231 reads the back side of the original by conveying the original once by the original feeding unit 21. When the dust detection unit 612 detects dust adhering to the CIS 231 when the double-sided simultaneous reading mode is set, the mode setting unit 611 cancels the setting of the double-sided simultaneous reading mode and reads both sides simultaneously. The mode is forbidden, that is, cannot be set by the user, and is set to the double-sided reverse reading mode.

  The dust detection unit 612 detects dust attached to the CIS 231. Here, for example, the dust detection unit 612 causes the CIS 231 to read the white roller 219 (see FIG. 1) disposed so as to face the CIS 231, causes the image processing unit 64 to perform shading correction, and The image data after shading correction is added for each pixel arranged in one line in the main scanning direction constituting the CIS 231. If there is a pixel whose added value exceeds a certain level, dust adheres to the pixel. Judge that

  In addition, when the duplex setting mode is set by the mode setting unit 611, the dust detection unit 612 executes a process of detecting dust adhesion every time each document is read by the CIS 231 during continuous document reading. In this case, the mode setting unit 611 cancels the setting of the double-sided simultaneous reading mode and sets the double-sided reverse reading mode when the dust detection unit 612 detects the adhesion of dust, and sets the rest of the original on both sides. Read in reverse reading mode. Note that the dust detection unit 612 prevents CIS 231 from adhering before each document is read by the CIS 231, that is, before the first document in the document bundle is read by the CIS 231 and between the documents. To detect.

  Further, in this case, even when dust is detected by the dust detection unit 612, the mode setting unit 611 cancels the setting of the double-sided simultaneous reading mode when the size of the detected dust is smaller than a predetermined size. First, the image processing unit 64 is caused to perform image processing for reducing deterioration in image quality due to dust in the image data of the document read by the CIS 231. Here, a size that can be removed by image processing can be adopted as the predetermined size.

  As image processing, for example, processing for replacing image data read by pixels of the CIS 231 determined to have dust attached by the dust detection unit 612 using the neighboring pixel data, Image processing such as replacement with image data and smoothing processing using neighboring pixel data may be employed as appropriate.

Further, the dust detection unit 612 executes processing for detecting whether dust is attached to a predetermined document reading position RP set in the reading window 230 in the scanner unit 23. Here, the dust detection unit 612 may detect adhesion of dust using a method described in, for example, Japanese Patent Application Laid-Open No. 2000-310820, or, for example, a shading plate (not shown) may be added to the CCD 229 for one or more lines. A process is adopted in which the sum of gradation values is calculated for each pixel of the CCD 229, and when there is a pixel exceeding a predetermined value, it is determined that dust is attached on the optical axis of the pixel. May be. Incidentally, the document reading position RP indicates the line of intersection between the optical axis and the reading window 230 of the reflected light from the original toward the first mirror 223 as shown in FIG. 1, the main scanning direction as the longitudinal direction.

  The document feeder 21 automatically captures a document placed on the document tray 211 when the document is copied or scanned in the ADF reading mode so that the document can be read by the CCD 229 or the CIS 231. Transport.

  The display unit 63 is for displaying various screens, and displays the display screen based on a display signal input from the control unit 61.

  The image processing unit 64 performs various image processing relating to image data. For example, the image processing unit 64 processes image data acquired by the CCD 229 or the CIS 231 or image data transferred via the communication unit 66 from a personal computer connected via a network, a facsimile machine connected via a public line, or the like. Then, correction processing such as level correction and gamma correction, image data compression or expansion processing, and image processing processing such as enlargement or reduction processing are performed.

  The recording unit 40 forms on the recording paper an image based on image data obtained by the CCD 229 or the CIS 231 or image data transferred from the personal computer or facsimile apparatus via the communication unit 66.

  The communication unit 66 uses a network interface to transmit / receive various data to / from an external device such as a computer or a facsimile machine connected via a network.

  Next, the operation of the multifunction machine 1 will be described with reference to the flowchart shown in FIG. First, when a bundle of documents is placed on the document tray 211 and an instruction for starting document reading is received by the operation unit 5, the document feeder 21 picks up one document from the document tray 211. When the mode setting unit 611 is set to the double-sided simultaneous reading mode (YES in step S1), the process proceeds to step S2 and is set to the double-sided reverse reading mode. (NO in step S1), the MFP 1 is caused to read the original in the double-sided reverse reading mode (step S9).

  Next, in step S2, the dust detection unit 612 determines whether dust is attached to the CIS 231. If dust is attached to the CIS 231 (YES in step S2), the dust attached to the CIS 231 is determined. Is determined to be larger than the predetermined size (step S3), and if dust is not attached to the CIS 231 (NO in step S2), the process proceeds to step S11, and in the double-sided simultaneous reading mode, that is, The front surface of the document is read by the CCD 229, and the back surface of the document is read by the CIS 231.

  Here, the dust detection unit 612 determines that the size of the dust is larger than the predetermined size when, for example, the CIS 231 has a predetermined number or more of pixels that are determined to have dust attached continuously (see FIG. In step S3, the process proceeds to step S4. When the predetermined number or more of pixels determined to have dust are not continuously present, it is determined that the size of the dust is equal to or smaller than the predetermined size (step S3). NO), the process proceeds to step S6.

  In step S4, the mode setting unit 611 switches from the double-sided simultaneous reading mode to the double-sided reverse reading mode, disables the double-sided simultaneous reading mode (step S5), and returns the process to step S1. Thereafter, the original is read in the double-sided reverse reading mode, and the user cannot set the double-sided simultaneous reading mode by operating the operation unit 5. Therefore, even when the user places the bundle of documents on the document tray 211 again, even if the user performs an operation for setting the double-sided simultaneous reading mode on the operation unit 5, the mode setting unit 611 sets the double-sided simultaneous reading mode. Without executing the next job, the next job is executed in the double-sided reverse reading mode.

  In step S <b> 6, the mode setting unit 611 reads the multifunction device 1 in the double-sided simultaneous reading mode, that is, the front side of the original is read by the scanner unit 23 and the back side of the original is read by the CIS 231. In step S <b> 7, the image processing unit 64 performs the above-described image processing on the image data of the document read by the CIS 231, and corrects image quality degradation due to dust attached to the CIS 231.

  In step S8, the recording unit 40 forms the image data read by the scanner unit 23 on the surface of the recording paper, then switches back the recording paper, and forms the image data read by the CIS 231 on the back surface of the recording paper. And then eject the recording paper.

  Next, when the next document remains in the document tray 211 in step S10 (YES in step S10), the process returns to step S1, the same process is performed on the next document, and the document tray 211 is processed. If the next original does not remain (NO in step S10), the process ends. Here, the determination of whether or not a document remains on the document tray 211 can be easily realized by providing a document detection sensor (not shown) in the vicinity of the document tray 211.

  As described above, according to the multi-function device 1, when dust adhesion is detected on the CIS 231, the double-sided simultaneous reading mode is canceled and the double-sided reverse reading mode that does not use the CIS 231 is set. When is attached, image data can be read without degrading the image quality.

  In addition, during the continuous reading of the original, each time the original is read by the CIS 231, a process for detecting the adhesion of dust in the CIS 231 is executed. Therefore, when dust adheres to the CIS 231 during the continuous reading, the image data can be read without degrading the image quality.

  Further, even when dust adhesion on the CIS 231 is detected, if the size of the dust is small, the document is read in the double-sided simultaneous reading mode, and dust appearing in the obtained image data is removed by image processing. Therefore, the double-sided simultaneous reading mode capable of high-speed reading is continuously set. As a result, double-sided reading can be performed at high speed.

(Embodiment 2)
Next, a case where the image reading apparatus and the image forming apparatus according to the second embodiment of the present invention are integrated in the multifunction machine 1a will be described. In the present embodiment, the same components as those in the first embodiment will not be described, and only differences will be described. The overall configuration diagram and block diagram are the same as those in the first embodiment.

  The multifunction device 1a according to the second embodiment detects whether or not dust is present at the document reading position RP of the scanner unit 23 before starting reading of the document bundle, and if dust is present, The document reading position RP is set to a position where no dust exists.

  FIG. 5 shows a block diagram of the multifunction machine 1a. The position setting unit 613 sets the document reading position RP to a different position in the reading window 230 when the dust detection unit 612 detects adhesion of dust. Here, the position setting unit 613 sets the reading position to a different position using the method described in Japanese Patent Laid-Open No. 2000-310820. Specifically, the first mirror 223 is moved by a predetermined distance in the sub-scanning direction, the document reading position RP is moved by a predetermined distance in the sub-scanning direction, and the dust detection unit 612 is again executed with the dust detection process described above. By repeating these processes, the document reading position RP is set.

  FIG. 6 is a flowchart showing the operation of the multifunction machine 1a. First, when a document bundle is placed on the document tray 211 and an instruction for starting document reading is received by the operation unit 5 by the user, the CCD 229 is caused to read the shading plate, and dust is present at the document reading position RP. In the case where dust is present at the document reading position RP (YES in step S21), processing for changing the document reading position RP is executed (step S22), and dust is detected at the document reading position RP. Is not present (NO in step S21), the process of step S22 is passed through and the process proceeds to step S23.

  Next, when the double-sided simultaneous reading mode is set (YES in step S23), the process proceeds to step S24, and when the double-sided reverse reading mode is set (NO in step S23), the double-sided reverse reading mode is set. Then, the document is read (step S31), and the process is terminated.

  FIG. 7 is a flowchart showing the subroutine of step S23. First, in step S41, the position setting unit 613 moves the first mirror 223 by a predetermined distance and moves the document reading position RP by a predetermined distance. In step S42, the dust detection unit 612 causes the CCD 229 to read the shading plate again, and determines whether dust is present at the document reading position RP moved by a predetermined distance. In step S43, when the dust detection unit 612 detects the presence of dust at the document reading position RP (YES in step S43), the process returns to step S41, and when dust adhesion is not detected at the document reading position RP. (NO in step S43), the position moved in step S41 is set as the document reading position RP (step S44).

  Here, the document reading position RP is shifted from the center position in the sub-scanning direction of the reading window 230 by a predetermined distance toward the left end, set to a predetermined leftmost position, and then from the center position. It is moved so as to be shifted by a predetermined distance toward the right end. The processes in steps S24 to S33 shown in FIG. 6 are the same as the processes in steps S2 to S11 shown in FIG.

  As described above, according to the multifunction peripheral 1a, when dust is attached to the document reading position RP, the document reading position RP is set to a different position where dust does not exist. Can be read.

1 is a longitudinal sectional view schematically showing an internal configuration of a multifunction machine according to an embodiment of the present invention. It is the figure which showed an example of the front view of an operation part. FIG. 2 is a block diagram illustrating an electrical configuration of the multifunction machine illustrated in FIG. 1. 6 is a flowchart illustrating an operation of the multifunction machine. It is a block diagram which shows the electric constitution of the multifunctional device concerning Embodiment 2 of this invention. 6 is a flowchart showing the operation of the multifunction machine according to the second embodiment of the present invention. It is a flowchart which shows the subroutine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunctional device 2 Image reading apparatus 23 Scanner part 61 Control part 64 Image processing part 230 Reading window 611 Mode setting part 612 Dust detection part 613 Position setting part RP Original reading position

Claims (4)

A document feeder for transporting documents,
A first reading unit that reads one side of a document conveyed by the document feeding unit;
A second reading unit for reading the other side of the document conveyed by the document feeding unit;
A reversing unit for reversing and transporting the document so that the other side is read by the first reading unit after the first reading unit has finished reading one side of the document;
A two-sided reverse reading mode in which one side of the original is read by the first reading unit and the other side of the original is read by the first reading unit after the original is reversed by the reversing unit; A mode in which the first reading unit reads one side of the document and the second reading unit reads the other side of the document in one-sided simultaneous reading mode in one-time document conveyance by A setting section;
A dust detection unit for detecting dust adhering to the second reading unit,
Wherein the mode setting unit, the even when the by dust detector adhesion of dust is detected, if the size of the detected dust is greater Ri by predetermined size, thereby setting the dual-side scanning mode Without setting the double-sided reverse reading mode,
The dust detection unit is configured to detect adhesion of dust every time each document is read by the second reading unit during continuous document reading when the duplex setting mode is set by the mode setting unit. Run
The mode setting unit cancels the setting of the double-sided simultaneous reading mode when dust attachment is detected by the dust detection unit and the size of the detected dust is larger than a predetermined size. To set the double-sided reverse reading mode, and read the remaining document in the double-sided reverse reading mode,
The mode setting unit causes the first reading unit to read a white roller disposed opposite to the first reading unit, and the obtained image data is arranged in one line in the main scanning direction. Addition is performed for each pixel that constitutes the first reading unit, and when the addition value exceeds a certain level and a predetermined number or more of pixels are continuously present, the size of the detected dust is preliminarily determined. Judge that it is larger than the set size,
The first reading unit includes a reduction optical system image sensor,
The second reading unit includes a contact optical system image sensor,
The first reading unit reads a document at a predetermined document reading position,
The dust detection unit further executes a process of detecting whether dust is present at the document reading position,
When the dust detection unit detects the presence of dust at the document reading position, the dust detection unit further includes a position setting unit that sets the document reading position to a position where dust does not exist,
The position setting unit moves the document reading position by a predetermined distance in the sub-scanning direction, causes the dust detection unit to execute again a process of detecting whether dust exists at the document reading position, and An image reading apparatus , wherein the document reading position is set by repeating processing .   The image reading apparatus according to claim 1, wherein the mode setting unit prohibits the double-sided simultaneous reading mode when dust adhesion is detected by the dust detection unit. An image processing unit;
The mode setting unit does not cancel the setting of the double-sided simultaneous reading mode when the size of the detected dust is smaller than a predetermined size even when dust is detected by the dust detection unit. The image reading apparatus according to claim 1, wherein the image processing unit causes the image processing unit to perform image processing for reducing deterioration in image quality due to dust in image data of the document read by the second reading unit. An image reading apparatus according to any one of claims 1 to 3,
An image forming apparatus comprising: an image forming unit configured to form an image on a recording sheet based on read image data read by the first reading unit and the second reading unit.

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