JP6369370B2 - Image reading apparatus, image processing apparatus, and image reading apparatus control method - Google Patents

Description

  The present invention relates to an image reading apparatus, an image processing apparatus including the image reading apparatus, and a method for controlling the image reading apparatus.

  In general, an image reading apparatus includes an image scanning unit that scans a document while detecting the amount of light emitted from the document placed on a transparent document table. The image scanning unit includes a light emitting unit that irradiates light on a document and an image sensor that receives reflected light from a linear region along the main scanning direction of the document, and scans the document along the sub-scanning direction. The image sensor outputs a data string corresponding to the detected light amount for each pixel of the linear region in the document. The sub-scanning direction is a direction orthogonal to the main scanning direction.

  The image data of the two-dimensional image of the document is obtained by synthesizing along the sub-scanning direction a data string of the image density of the linear region obtained through the image scanning unit. An image processing apparatus such as a copying machine includes an image reading apparatus and an image forming apparatus. An image forming apparatus of a copying machine forms a secondary image on a recording sheet by sequentially forming on the recording sheet a linear image corresponding to an image density data string of the linear region obtained through the image scanning unit. .

  Further, normal image density data obtained when the light quantity of the light emitting unit is set to a normal light quantity, and comparison image density data obtained when the light quantity of the light emitting part is set to another comparative light quantity, It is known that a pixel region having a large density difference is specified as a document region (see, for example, Patent Document 1).

JP 2013-110506 A

  By the way, in the image reading apparatus, the document scanning may be performed by the image scanning unit in a state where the cover of the document table is opened. In this case, a noise image caused by external light such as room lighting entering the image sensor tends to appear in the document outside area.

  In order to remove the noise image in the area outside the original, it is conceivable to specify the original area from the image data. For example, it is conceivable to detect the boundary position between the document area and the document outside area by edge detection processing. It is also conceivable to specify a pixel area having a large density difference between the normal image data obtained with the normal light quantity and the comparison image data obtained with the comparative light quantity as the document area.

  However, in the above-described processing for specifying the document area, there may occur a situation in which the document area cannot be correctly specified without a significant difference in density when the background state of the document is various. For example, there may occur a situation in which the document area cannot be correctly specified in one of the case where the background of the document is a light color close to white and the color close to black.

  Therefore, it is desired that a noise image appear in the area outside the document due to the influence of external light regardless of the difference in the background state of the document.

  An object of the present invention is to prevent a noise image from appearing in an area outside a document due to the influence of external light, regardless of the state of the background of the document, when the document is scanned with the document table cover open. An image reading apparatus, an image processing apparatus, and a method for controlling the image reading apparatus are provided.

  An image reading apparatus according to one aspect of the present invention includes a light emitting unit, an image scanning unit, a light emission control unit, a scanning control unit, a first temporary area dividing unit, a second temporary area dividing unit, and a main area. And a section. The light emitting unit emits light toward a document placed on a transparent document table. The image scanning unit can execute an image reading process. The image reading process is performed on the document table along the sub-scanning direction orthogonal to the main scanning direction while detecting the amount of light emitted from the linear region along the main scanning direction on the document table for each pixel. This is a process of sequentially outputting an image data sequence corresponding to the detected light amount for each pixel in the linear region by scanning. The light emission control unit executes a process of switching the state of the light emitting unit between a reference state and a comparison state while alternately selecting an extinguished state and a brightening state as the comparison state. The reference state of the light emitting unit is a state in which light is emitted with a predetermined reference light amount. The comparison state of the light emitting unit is a state different from the reference state. The brightening state is a state in which light is emitted with a larger amount of light than the reference state. The scanning control unit causes the image scanning unit to execute the image reading process in parallel with switching of the state of the light emitting unit. Each time the first image data string is obtained, the first temporary area segmentation unit includes the first image data string and the second image data string obtained one time before the first image data string is obtained. Each pixel is divided into a document area pixel and a document outside area pixel according to a difference in data of the pixels corresponding to each other. The first image data string is the image data string corresponding to the reference state of the light emitting unit. The second image data string is the image data string corresponding to the comparison state of the light emitting unit. Each time the second image data string is obtained, the second temporary area segmenting unit obtains the first image data string obtained one time before the second image data string and the second image data string are obtained. Each of the pixels is divided into the document area pixel and the document outside area pixel according to a difference in data of the pixels corresponding to each other. The main area sorting section classifies each pixel into the original area pixel and the non-original area pixel for each switching period of the reference state and the comparison state of the light emitting section. At this time, the main area dividing unit divides the pixels divided into the original area pixels by at least one of the first temporary area dividing part and the second temporary area dividing part into the original area pixels, The pixel is divided into the original area pixel.

  An image processing apparatus according to another aspect of the present invention includes the image reading apparatus according to one aspect of the present invention and an image forming apparatus. The image forming apparatus forms an image corresponding to the plurality of first image data strings obtained by the image reading apparatus on a recording sheet.

  An image reading apparatus control method according to another aspect of the present invention includes the following steps. The first step is a step of executing a process of alternately switching the state of the light emitting unit between the reference state and the comparison state while alternately selecting the extinguishing state and the brightening state as the comparison state. The second step is a step of causing the image scanning unit to execute the image reading process in parallel with the switching of the state of the light emitting unit. The third step is a step of executing the first temporary area segmentation process every time the first image data string is obtained. The second provisional area segmentation process includes a difference in data of the pixels corresponding to each other in the first image data string and the second image data string obtained one time before the first image data string is obtained. In this process, each of the pixels is divided into the original area pixel and the non-original area pixel. The fourth step is a step of executing a second temporary area division process every time the second image data sequence of the light emitting unit is obtained. The second provisional area segmentation process includes a difference between the pixel data corresponding to each other in the second image data string and the first image data string obtained one time before the second image data string is obtained. In this process, each of the pixels is divided into the original area pixel and the non-original area pixel. The fifth step is a step of executing a main area dividing process for each switching cycle of the reference state and the comparison state of the light emitting unit. In the main area dividing process, the pixels divided into the original area pixels by at least one of the first temporary area dividing process and the second temporary area dividing process are divided into the original area pixels, and the other pixels are classified into the original area pixels. This is a process of dividing the original area pixel.

  According to the present invention, when a document is scanned with the cover of the document table opened, a phenomenon in which a noise image appears in an area outside the document due to the influence of external light regardless of the state of the background of the document is avoided. It is possible to provide an image reading apparatus, an image processing apparatus, and a control method for the image reading apparatus.

FIG. 1 is a configuration diagram of an image processing apparatus including the image reading apparatus according to the first embodiment. FIG. 2 is a block diagram of an image processing related device provided in the image reading apparatus according to the first embodiment. FIG. 3 is a block diagram of an image processing unit in the image reading apparatus according to the first embodiment. FIG. 4 is a time chart illustrating a state change of the light emitting unit and a data state change of the image processing unit in the image processing apparatus according to the first embodiment. FIG. 5 is a diagram illustrating an example of a document. FIG. 6 is a diagram illustrating an example of a two-dimensional image synthesized from an image data sequence obtained when the light emitting unit is turned on in the image reading apparatus according to the first embodiment. FIG. 7 is a diagram illustrating an example of a two-dimensional image synthesized from an image data sequence obtained when the light emitting unit is turned off in the image reading apparatus according to the first embodiment. FIG. 8 is a diagram illustrating an example of a two-dimensional image synthesized from an image data sequence output by the image reading apparatus according to the first embodiment. FIG. 9 is a block diagram of an image processing unit in the image processing apparatus according to the second embodiment. FIG. 10 is a graph showing the distribution of the values of the image data sequence obtained by the image scanning unit when different amounts of light are irradiated on the document whose background is light. FIG. 11 is a graph showing the distribution of the values of the image data sequence obtained by the image scanning unit when different amounts of light are irradiated on the document whose background is dark.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: It does not have the character which limits the technical scope of this invention.

[First Embodiment]
First, the configuration of the image processing apparatus 10 including the image reading apparatus 1 according to the first embodiment will be described with reference to FIGS. The image processing apparatus 10 includes an image reading apparatus 1 and an image forming apparatus 2. Further, the image processing apparatus 10 also includes a control unit 8 and an operation display unit 80 that are common to the image reading apparatus 1 and the image forming apparatus 2.

  For example, the image processing apparatus 10 is a copying machine, a printer or a facsimile machine having a copying machine function, or a multifunction machine having a plurality of image processing functions including an image reading function.

  As shown in FIG. 1, the image reading apparatus 1 includes a transparent document table 13, an image scanning unit 11, and a document table cover 12. An ADF (Auto Document Feeder) 120 is incorporated in the document table cover 12.

  The document table 13 is a portion on which a document 90 that is an image reading object is placed. Generally, the document table 13 is called platen glass. The document table cover 12 is supported by the casing 100 of the image processing apparatus 10 so as to be rotatable between a closed position that covers the document table 13 and an open position that releases the document table 13.

  The image scanning unit 11 includes a light emitting unit 112, a scanning mechanism 111, an optical system 113 such as a mirror and a lens, an image sensor 114, and the like. In the following description, one direction in the horizontal plane and a direction perpendicular thereto are referred to as a main scanning direction R1 and a sub-scanning direction R2, respectively.

  The light emitting unit 112 is a light source that irradiates light toward the document 90 placed on the transparent document table 13. The light emitting unit 112 irradiates the document 90 with the strip-shaped light along the main scanning direction R <b> 1 through the document table 13. For example, it is conceivable that the light emitting unit 112 is an LED array including a plurality of light emitting diodes arranged along the main scanning direction R1. It is also conceivable that the light emitting unit 112 is a straight tubular fluorescent lamp along the main scanning direction R1.

  The optical system 113 includes a mirror and a lens for guiding emitted light from a linear region on the document table 13 along the main scanning direction R1 to the light receiving unit of the image sensor 114. When the document 90 is placed on the document table 13, the emitted light from the linear area on the document table 13 includes the emitted light from the document 90 and the emitted light from the region outside the document. When the light emitting unit 112 is turned on, the light emitted from the original 90 is reflected light of the light emitted from the light emitting unit 112 irradiated on the original 90.

  When the document table cover 12 is closed, the emitted light from the outside region of the document is emitted light from the inner surface of the document table cover 12. In the state where the document table cover 12 is closed, the inner surface of the document table cover 12 is along the surface of the document table 13.

  In a state where the document table cover 12 is opened, the emitted light from the outside region of the document is external light that enters the document table 13 from above the document table 13. This external light causes a noise image in the area outside the document in the image read by the image reading apparatus 1.

  The image sensor 114 detects the amount of light emitted from the linear region along the main scanning direction R1 on the document table 13 for each pixel, and uses the detected light amount data of each pixel as an image data string of the linear region. It is a sensor that outputs. For example, the image sensor 114 may be a CCD (Charge Coupled Device) 114.

  The image sensor 114 outputs an image data string corresponding to the detected light amount for each pixel in the linear region. The image data string includes data of a plurality of pixels that are partitioned regions in the main scanning direction R1 in the linear region.

  The scanning mechanism 111 is a mechanism that supports a part of the light emitting unit 112 and the optical system 113 and moves it along the sub-scanning direction R2. Thereby, the position in the sub-scanning direction R <b> 2 of the linear region that is the light irradiation target of the light emitting unit 112 is changed. The linear region irradiated with light from the light emitting unit 112 is also a target for detecting the amount of emitted light by the image sensor 114. The scanning mechanism 111 also includes a driving unit (not shown) such as a stepping motor.

  The scanning mechanism 111 moves a part of the optical system 113 that guides light from the light emitting unit 112 and the linear region to the image sensor 114 along the sub-scanning direction R2. As a result, the image scanning unit 11 scans the document table 13 along the sub-scanning direction R2 while detecting the amount of light emitted from the linear region along the main scanning direction R1 on the document table 13 for each pixel. . In a state where the document 90 is placed on the document table 13, a part or all of the scanning target of the image scanning unit 11 is the document 90.

  Note that a contact image sensor (CIS) in which the light emitting unit 112, the image sensor 114, and the lens are integrated may be employed in the image scanning unit 11. In this case, the contact image sensor is supported by the scanning mechanism 111 so as to be movable along the sub-scanning direction R2.

  The ADF 120 conveys the document 90 set on the document tray 121 to the document discharge tray 123 via the image reading position by a plurality of rotating conveyance rollers 122. At that time, the image scanning unit 11 reads the image of the document 90 in a state where the scanning mechanism 111 is stopped at the image reading position.

  In the example illustrated in FIG. 1, the image reading apparatus 1 also includes a document sensor 801 and a cover sensor 802. The document sensor 801 is a sensor that detects whether or not the document 90 is set on the document tray 121. The cover sensor 802 is a sensor that detects whether or not the document table cover 12 is closed.

  As described above, the image scanning unit 11 scans the document table 13 along the sub-scanning direction R2 while detecting the amount of light emitted from the linear region on the document table 13 for each pixel. Thereby, the image scanning unit 11 can execute an image reading process for sequentially outputting the image data sequence corresponding to the detected light amount for each pixel in the linear region.

  The image forming apparatus 2 is an apparatus that forms an image on the recording sheet 9 according to the image data string output from the image reading apparatus 1. The recording sheet 9 is a sheet-like image forming medium such as paper, coated paper, postcard, envelope, and OHP sheet.

  For example, the image forming apparatus 2 includes a sheet conveying unit 3, an image forming unit 4, an optical scanning unit 5, a fixing unit 6, and the like. An image forming apparatus 2 shown in FIG. 1 is an electrophotographic image forming apparatus. It is also conceivable that the image forming apparatus 2 is an image forming apparatus of another method such as an ink jet method.

  In the sheet conveying unit 3, the sheet delivery unit roller 31 sends the recording sheet 9 from the sheet storage unit 30 to the sheet conveying path 300. Further, the sheet conveyance roller 32 conveys the recording sheet 9 along the sheet conveyance path 300. Further, the discharge roller 33 discharges the recording sheet 9 on which the image has been formed from the exit of the sheet conveyance path 300 onto the recording sheet discharge tray 101.

  The image forming unit 4 forms an image on the surface of the recording sheet 9 moving on the sheet conveyance path 300. The image forming unit 4 includes a drum-shaped photoreceptor 41, a charging unit 42, a developing unit 43, a transfer unit 45, a cleaning unit 47, and the like. The photoconductor 41 is an example of an image carrier.

  The photoconductor 41 rotates, and the charging unit 42 uniformly charges the surface of the photoconductor 41. Further, an electrostatic latent image is written on the surface of the photoreceptor 41 charged by the optical scanning unit 5 scanning the laser beam. Further, the developing unit 43 supplies the developer to the photosensitive member 41 to develop the electrostatic latent image into the image of the developer. The developer is supplied to the developing unit 43 from a developer supply unit (not shown).

  Further, the transfer unit 45 transfers the image of the developer on the surface of the photosensitive member 41 to the recording sheet 9 moving on the sheet conveyance path 300. Finally, the cleaning unit 47 removes the developer remaining on the surface of the photoreceptor 41.

  The fixing unit 6 sandwiches the recording sheet 9 on which an image is formed between a fixing roller 61 including a heater such as a halogen heater and a pressure roller 62, and sends the recording sheet 9 to a subsequent process. As a result, the fixing unit 6 heats the image that is the image of the developer on the recording sheet 9 and fixes the image on the recording sheet 9.

The control unit 8 controls various electric devices included in the image processing apparatus 10 based on input information input through the operation display unit 80 and detection results of various sensors including the document sensor 801 and the cover sensor 802.
The control unit 8 displays an operation menu or the like on the operation display unit 80. Further, the control unit 8 performs image processing on an image input through the image reading device 1. further,

  For example, as shown in FIG. 2, the control unit 8 includes an MPU (Micro Processor Unit) 81, a storage unit 82, a scanning control unit 83, a light emission control unit 84, an image processing unit 85, a laser control unit 86, a signal interface 87, and the like. Is provided.

  The MPU 81 is a processor that executes various arithmetic processes. The storage unit 82 is a nonvolatile information storage medium in which information such as programs Pr1 and Pr2 for causing the MPU 81 to execute various processes is stored in advance. Furthermore, the storage unit 82 is also an information storage medium in which various information can be read and written by the MPU 81.

  The control unit 8 comprehensively controls the image processing apparatus 10 by the MPU 81 executing various programs Pr1 and Pr2 stored in the storage unit 82 in advance.

  The signal interface 87 is an interface circuit that relays signal exchange between the MPU 81 and the sensor, control target device, and the like. The MPU 81 inputs detection signals (measurement signals) from various sensors such as the document sensor 801 and the cover sensor 802 via the signal interface 87. Further, the MPU 81 outputs a control signal to the control target device via the signal interface 87.

  The scanning control unit 83 controls the scanning mechanism 111 of the image scanning unit 11 so that the scanning position in the sub-scanning direction R2 by the image scanning unit 11, that is, the position of the linear region that the image scanning unit 11 scans. To control.

  The light emission control unit 84 controls the light emitting unit 112 of the image scanning unit 11 and switches the light emitting state of the light emitting unit 112 according to the situation. The image processing unit 85 inputs image data obtained through the image scanning unit 11 and executes image processing.

  The laser control unit 86 inputs the recording image data sequence output from the image processing unit 85, and adjusts the amount of laser light output from the optical scanning unit 5 in accordance with the density of each pixel indicated by the recording image data sequence. To do.

  In the following description, an area where the original 90 is present in all the scanning areas of the image scanning unit 11 on the original table 13 is referred to as an original area, and the remaining area is referred to as an area outside the original.

  By the way, in the image reading apparatus 1, the document 90 may be scanned by the image scanning unit 11 with the document table cover 12 opened. In this case, a noise image caused by external light such as room lighting entering the image sensor 114 tends to appear in the outside area of the document.

  In order to remove the noise image in the area outside the original, it is conceivable to specify the original area from image data. For example, it is conceivable to detect a boundary position between the document area and the document outside area by edge detection processing. It is also conceivable to specify a pixel area having a large density difference between the normal image data obtained with the normal light quantity and the comparison image data obtained with the comparative light quantity as the document area.

  However, in the above-described processing for specifying the document area, when the background state of the document 90 is various, there may occur a situation in which the document area cannot be specified correctly without the density difference being noticeable. For example, there may occur a situation in which the document area cannot be correctly specified in one of a case where the background of the document 90 is a light color close to white and a color close to black.

  FIG. 10 is a graph showing a distribution of values of the image data sequence obtained by the image scanning unit 11 when different amounts of light are irradiated on the original 90 having a light background such as white. FIG. 11 is a graph showing the distribution of the values of the image data sequence obtained by the image scanning unit when different amounts of light are irradiated on a document whose background is a dark color such as black.

  10 and 11, the horizontal axis represents the position in the main scanning direction R1, and the vertical axis represents the data value of each pixel in the image data sequence. The data value of each pixel corresponds to the amount of light detected by the image sensor 114.

  10 and 11, a solid line graph g0 is a value of an image data string obtained when the light emitting unit 112 is in a reference state in which the light emitting unit 112 emits light with a reference light amount, and a broken line graph g1 indicates that the light emitting unit 112 is off. The values of the image data sequence obtained at times and the broken line graph g2 indicate the values of the image data sequence obtained when the light emitting unit 112 is in a light-intensifying state in which light is emitted with a light amount larger than the reference light amount. The reference light amount is a light amount of the light emitting unit 112 that is set in a normal image reading process for reading an image of the document 90.

  10 and 11, ΔB1 is the pixel value of the background portion of the document 90 in the image data sequence in the reference state and the pixel value of the background portion of the document 90 in the image data sequence in the unlit state. It is a difference. ΔB2 is the difference between the pixel value of the background portion of the document 90 in the image data sequence in the reference state and the pixel value of the background portion of the document 90 in the image data sequence in the bright state. Hereinafter, the former is referred to as a first difference ΔB1, and the latter is referred to as a second difference ΔB2.

  As shown in FIG. 10, when the background color of the original 90 is light, the second difference ΔB2 is smaller than the first difference ΔB1. Therefore, when the background color of the original 90 is light, if the second difference ΔB2 is used for specifying the original area, a situation may occur in which the original area cannot be specified correctly.

  On the other hand, as shown in FIG. 11, when the background color of the original 90 is dark, the first difference ΔB1 is smaller than the second difference ΔB2. For this reason, when the first difference ΔB1 is used for specifying the document area, it may occur that the document area cannot be specified correctly.

  The image reading apparatus 1 according to the present embodiment has a function for avoiding a phenomenon in which a noise image appears in the area outside the original document due to the influence of external light regardless of the difference in the state of the background of the original document 90. The function will be described below with reference to FIGS.

  FIG. 3 is a block diagram of the image processing unit 85. FIG. 4 is a time chart showing a state change of the light emitting unit 112 and a data state change of the image processing unit 85.

[Light emission control unit 84]
The light emission control unit 84 controls the light emission state Le of the light emitting unit 112. More specifically, the light emission control unit 84 has three light emission states Le: a light-off state, the reference state that emits light with the reference light amount, and the light-increasing state that emits light with a light amount larger than the reference light amount. Can be set to either. The amount of light emitted from the light emitting unit 112 in each of the reference state and the brightening state is determined in advance.

  In the present embodiment, when the operation mode signal Md is a signal representing the open scanning mode, the light emission control unit 84 alternately changes the state of the light emitting unit 112 between the reference state and a comparison state different from the reference state. Switch. At that time, the light emission control unit 84 alternately selects the extinguishing state and the brightening state as the comparison state. In FIG. 4, “STN” represents the standard state, “CMP” represents the comparison state, “OFF” represents the extinguishing state, and “UP” represents the brightening state.

  Accordingly, as shown in FIG. 4, the light emission state Le alternately changes between the comparison state (“CMP”) and the standard state (“STN”). At that time, the comparison state (“CMP”) is alternately switched between the extinguishing state (“OFF”) and the brightening state (“UP”). Therefore, it can be said that the light emission state Le periodically changes with the change in the order of the light-off state, the standard state, the light-intensifying state, and the standard state as one cycle.

  The light emission control unit 84 outputs a shift gate signal Gs for causing the image sensor 114 to output the primary image data sequence X0 every time the light emitting unit 112 is switched between the standard state and the comparison state. At that time, one of the extinguishing state and the brightening state is alternately selected as the comparison state.

  Further, the light emission control unit 84 generates a synchronization signal Ss synchronized with the switching cycle of the light emitting unit 112 between the standard state and the comparison state, and supplies the synchronization signal Ss to the image processing unit 85.

  On the other hand, when the operation mode signal Md is a signal representing the closed scanning mode, the light emission control unit 84 sets the light emitting unit 112 to the reference state when the image scanning unit 11 operates. Thereby, the general image reading process is executed.

  For example, it is conceivable that the MPU 81 sets the operation mode signal Md according to an operation on the operation display unit 80 by the user by executing the operation mode setting program Pr1.

  It is also conceivable that the MPU 81 automatically sets the operation mode signal Md according to whether the detection results of the document sensor 801 and the cover sensor 802 satisfy a predetermined open scanning mode condition. In this case, the MPU 81 automatically sets the operation mode signal Md by executing the operation mode setting program Pr1.

  For example, in the open scanning mode condition, the document sensor 801 detects a state where the document 90 is not set on the document tray 121, and the cover sensor 802 indicates a state where the document table cover 12 is not closed. It is detecting. When the MPU 81 detects that a copy execution operation has been performed on the operation display unit 80 in a state where the open scan mode condition is satisfied, the MPU 81 sets the operation mode signal Md to the open scan mode state. In other cases, the operation mode signal Md is set to the closed scanning mode.

[Scanning Control Unit 83]
The scanning control unit 83 controls the scanning mechanism 111 and the image sensor 114 to cause the image scanning unit 11 to execute the image reading process. More specifically, the scanning control unit 83 controls the scanning mechanism 111 so that the light emitting unit 112 and a part of the optical system 113 that guides the light from the linear region to the image sensor 114 in the sub-scanning direction R2. Move to the target position in the scanning range. Further, the scanning control unit 83 controls the image sensor 114 to cause the image sensor 114 to output the image data string.

  When the scanning control unit 83 operates the image scanning unit 11, the image scanning unit 11 scans the scanning range from the start point to the end point in the sub-scanning direction R2.

  For example, each of the starting point and the end point in the scanning range may be a preset position. In this case, it is conceivable that the positions of the starting point and the ending point are positions at both ends of the scannable range in the sub-scanning direction R2 of the image scanning unit 11.

  It is also conceivable that the position of one or both of the start point and the end point is set within the scannable range by an operation on the operation display unit 80. For example, when information on the size and orientation of the document 90 is input to the operation display unit 80, one end of the scannable range is set as the position of the starting point, and the position corresponding to the size and orientation of the document 90 Is set as the position of the end point.

  It is also conceivable that the image processing unit 85 automatically sets one or both of the start point and the end point. In this case, the image processing unit 85 performs document edge detection processing for detecting one or both of the leading edge position and trailing edge position in the sub-scanning direction R2 of the document 90 on the document table 13, and the detection result is set as the starting point or the Set as end point. Various known algorithms can be employed as the document edge detection processing algorithm.

  In the present embodiment, the MPU 81 outputs an operation mode signal Md described later. The operation mode signal Md is a signal indicating one of the open scanning mode and the closed scanning mode as well as the start signal of the image reading process.

  When the MPU 81 detects that a predetermined reading start operation has been performed on the operation display unit 80, the MPU 81 outputs an operation mode signal Md to the scanning control unit 83, the light emission control unit 84, and the image processing unit 85. . The scanning control unit 83, the light emission control unit 84, and the image processing unit 85 execute the image reading process when the operation mode signal Md is input.

  The open scanning mode is an operation mode in which the document 90 on the document table 13 is scanned assuming that the document table cover 12 is opened. The closed scanning mode is an operation mode in which the document 90 on the document table 13 is scanned assuming that the document table cover 12 is closed.

  When the operation mode signal Md output from the MPU 81 is a signal representing the open scanning mode, the scanning control unit 83 operates the image scanning unit 11 at half the standard speed. On the other hand, when the operation mode signal Md is a signal representing the closed scanning mode, the scanning control unit 83 operates the image scanning unit 11 at the standard speed. That is, the moving speed of the image scanning unit 11 in the open scanning mode is half of the moving speed of the image scanning unit 11 in the closed scanning mode.

[Image processing unit 85]
As shown in FIG. 3, the image processing unit 85 includes a first delay buffer 851, a temporary region partitioning unit 852, a second delay buffer 853, a main region partitioning unit 854, and a data selection unit 856. Furthermore, the image processing unit 85 in the present embodiment also includes a preprocessing unit 850, a replacement unit 855, and a postprocessing unit 857. For example, the image processing unit 85 may be configured by an ASIC (Application Specific Integrated Circuit) or a DSP (Digital Signal Pocessor).

  The preprocessing unit 850 performs well-known image correction processing such as shading correction and gamma correction on the primary image data sequence X0, and outputs a secondary image data sequence X1 that is an image data sequence after correction.

  The first delay buffer 851 is a buffer memory that temporarily stores image data sequences sequentially obtained through the image scanning unit 11 that is scanning the original 90 until the next new image data sequence is obtained. In the present embodiment, the first delay buffer 851 temporarily stores the secondary image data sequence X1 obtained sequentially through the image scanning unit 11 and the preprocessing unit 850.

  The first delay buffer 851 then outputs the previous secondary image data sequence X2 when a new secondary image data sequence X1 is obtained. Therefore, when the pre-processing unit 850 outputs the latest secondary image data sequence X1, the first delay buffer 851 outputs the secondary image data sequence X2 of the previous one in parallel.

  In FIG. 4, “Xoff”, “Xstn”, and “Xup” represent secondary image data strings X1, X2 corresponding to the extinguished state, the standard state, and the brightened state, respectively. When the latest secondary image data sequence X1 corresponding to the standard state is obtained by the action of the first delay buffer 851, the secondary image data sequence X2 of the previous time corresponding to the comparison state is simultaneously acquired. can get. Further, when the latest secondary image data sequence X1 corresponding to the comparison state is obtained, the secondary image data sequence X2 of the previous time corresponding to the standard state is obtained in parallel therewith.

  The temporary area dividing unit 852 executes a temporary area dividing process every time the image data sequence corresponding to each of the reference state and the comparison state of the light emitting unit 112 is obtained. In the example shown in FIG. 4, the temporary area dividing unit 852 executes the temporary area dividing process in synchronization with the shift gate signal Gs.

  In the temporary area dividing process, each pixel in the linear area is divided into a document area pixel and a document outside area pixel according to the difference between the latest secondary image data string X1 and the secondary image data string X2 of the previous time. It is processing to do. The classification result of the main area classification process, which will be described later, is the final classification result, whereas the classification result of the temporary area classification process is a classification result in the middle of obtaining the final result.

  The temporary area classification unit 852 outputs temporary area classification data Y1 representing the result of the temporary area classification processing. The temporary area classification data Y1 is data for discriminating between the original area pixel and the original area pixel for each pixel of the linear area.

  When the temporary area division data Y1 is 1-bit data for each pixel, the original area pixel and the non-original area pixel may be represented by “1” and “0”, respectively.

  The temporary area classification unit 852 determines the pixels as the original area pixel and the original according to the difference in the data of the pixels corresponding to each other in the latest secondary image data string X1 and the secondary image data string X2 immediately before. This is divided into outer area pixels. At this time, the provisional area classification unit 852 classifies the pixels in which the difference satisfies a predetermined document area condition into the document area pixels.

  For example, it is conceivable that the temporary area dividing unit 852 executes the pixel classification according to the first classification rule shown below. The first classification rule determines whether or not the document area condition is satisfied for each of the plurality of pixels continuous in the main scanning direction R1, classifies the pixels in the area satisfying the document area condition into the document area pixels, and others. The above-mentioned pixel is divided into the non-document area pixels.

  The document area condition in the first classification rule is a condition that the difference shows a difference larger than a predetermined threshold light amount difference continuously for a predetermined number or more in the main scanning direction.

  In addition, it is conceivable that the temporary area classification unit 852 executes the pixel classification according to the second classification rule shown below. In the second division rule, all pixels in the range from the pixel closest to the first end of the linear region to the pixel closest to the second end of the linear region in the pixels satisfying the document region condition are satisfied. The rule is to divide the pixels into the document area pixels.

  It is conceivable that the document area condition in the second classification rule is the same as the document area condition in the first classification rule. For example, it is conceivable that the MPU 81 has a function of selecting one of the first classification rule and the second classification rule in accordance with an operation on the operation display unit 80. In this case, the temporary area classification unit 852 executes the pixel classification according to the selected one classification rule.

  It is also conceivable that the temporary area classification unit 852 determines whether or not the document area condition is satisfied for each pixel, and classifies the pixels satisfying the document area condition into the document area pixels. In this case, the document area condition is a condition that the difference shows a difference larger than a predetermined light amount difference.

  In the present embodiment, the provisional area classification unit 852 includes a combination of the image data strings to be determined for the original area condition, that is, the latest secondary image data string X1 and the previous secondary image data string X2. There are two types of combinations.

  The first combination is a combination of two secondary image data strings X1, X2 corresponding to each of the standard state and the extinguishing state. In this case, the temporary area sorting unit 852 determines whether the first difference ΔB1 is larger than a predetermined first light amount difference when determining whether or not the document area condition is satisfied (FIGS. 10 and 11). reference).

  The second combination is a combination of two secondary image data strings X1 and X2 corresponding to each of the standard state and the brightening state. In this case, the provisional area sorting unit 852 determines whether or not the second difference ΔB2 shows a difference larger than a predetermined second light amount difference when determining whether or not the document area condition is satisfied (FIG. 10). , 11).

  The first light amount difference when the comparison state is the extinguishing state is different from the second light amount difference when the comparison state is the brightening state. In general, the first light amount difference corresponding to the extinguishing state is larger than the second light amount difference corresponding to the brightening state.

  The second delay buffer 853 is a buffer memory that temporarily stores the temporary area division data Y1 sequentially output by the temporary area division unit 852 until the temporary area division data Y1 corresponding to the next new secondary image data string X1 is obtained. It is.

  The second delay buffer 853 outputs the temporary area division data Y2 of the previous time when new temporary area division data Y1 corresponding to the new secondary image data string X1 is output. Therefore, when the temporary area segmenting unit 852 outputs the latest temporary area segment data Y1 corresponding to the latest secondary image data string X1, the second delay buffer 853 simultaneously outputs the previous temporary area segment data Y1. The division data Y2 is output.

  In FIG. 4, “Div1” is a temporary area obtained by the determination of the original area condition based on the first difference ΔB1 in the two secondary image data strings X1 and X2 corresponding to the standard state and the extinguished state, respectively. The division data Y1 and Y2 are represented. “Div2” is provisional area division data obtained by the determination of the original area condition based on the second difference ΔB2 in the two secondary image data strings X1 and X2 corresponding to the standard state and the brightening state, respectively. Y1 and Y2 are represented.

  Here, the secondary image data strings X1, X2 ("Xstn") corresponding to the reference state are referred to as first image data strings, and the secondary image data strings X1, X2 ("Xoff" corresponding to the comparison state). “Or“ Xup ”) is referred to as a second image data string.

  In the present embodiment, the provisional region sorting unit 852 performs the first time before the first image data sequence and the first image data sequence are obtained each time a new first image data sequence (“Xstn”) is obtained. The temporary area segmentation process using the difference between the pixel data corresponding to each other in the second image data sequence ("Xoff" or "Xup") obtained in the above is executed. The temporary area dividing unit 852 that executes the temporary area dividing process at this timing (between “K + 1” to “K + 2” and “K + 3” to “K + 4” in FIG. 4) is an example of the first temporary area dividing unit.

  In addition, each time the new second image data string (“Xoff” or “Xup”) is obtained, the temporary area sorting unit 852 performs the once operation to obtain the second image data string and the second image data string. The temporary area segmentation process using the difference between the pixel data corresponding to each other in the first image data string ("Xstn") obtained previously is executed. At this timing (between “K” and “K + 1” in FIG. 4, between “K + 2” and “K + 3” and between “k + 4” and “k + 5”), the temporary region partitioning unit 852 that executes the temporary region partitioning process is the second. It is an example of a temporary area division part.

  In addition, it is also conceivable that the first temporary area section and the second temporary area section are provided separately.

  The main area division unit 854 performs main area division data corresponding to the contents of the latest temporary area division data Y1 and the previous temporary area division data Y2 for each switching period of the reference state and the comparison state of the light emitting unit 112. Y3 is output. In the example shown in FIGS. 3 and 4, the main area segmenting unit 854 executes processing for outputting the main area segmenting data Y <b> 3 in synchronization with the synchronization signal Ss supplied from the light emission control unit 84.

  The main area segment data Y3 is also data for discriminating between the original area pixel and the non-original area pixel for each of the pixels in the linear area, similarly to the temporary area segment data Y1 and Y2. The main area division data Y3 is the final division result, while the temporary area division data Y1 and Y2 are the division results in the middle of obtaining the main area division data Y3.

  “Every cycle of switching between the reference state and the comparison state of the light emitting unit 112” means “every pair of the image data strings corresponding to each of the standard state and the comparison state of the light emitting unit 112 is obtained”. means.

  The main area dividing unit 854 divides the pixels divided into the original area pixels by at least one of the latest temporary area dividing data Y1 and the previous temporary area dividing data Y2 into the original area pixels, The pixels are divided into the original area pixels.

  For example, when the temporary area division data Y1 and Y2 are data in which the original area pixel is “1”, that is, “true”, and the non-original area pixel is “0”, that is, “false”, the main area dividing section 854 The logical sum data of the latest temporary area division data Y1 and the previous temporary area division data Y2 is output as main area division data Y3.

  As described above, in the image reading apparatus 1, the light emission control unit 84 executes the light emission control process shown below. In the light emission control step, the light emission control unit 84 performs a light emission state switching process for alternately switching the state of the light emitting unit 112 between the reference state and the comparison state. At that time, the light emission control unit 84 executes the light emission state switching process while alternately selecting the light-off state and the light-intensifying state as the comparison state.

  Further, in the image reading apparatus 1, the scanning control unit 83 causes the image scanning unit 11 to execute the image reading process in parallel with the switching of the state of the light emitting unit 112.

  In addition, every time the first image data sequence corresponding to the reference state of the light emitting unit 112 is obtained, the temporary region sorting unit 852 executes a first temporary region sorting process. The first provisional region segmentation process includes the processing of the pixel data corresponding to each other in the first image data sequence and the second image data sequence obtained one time before the first image data sequence is obtained. In this process, each pixel is divided into the original area pixel and the non-original area pixel by the difference.

  Similarly, every time the second image data sequence is obtained, the temporary area classification unit 852 executes a second temporary area classification process. The second temporary area segmentation process is performed by performing the pixel data corresponding to each other in the second image data string and the first image data string obtained one time before the second image data string is obtained. In this process, each pixel is divided into the original area pixel and the non-original area pixel by the difference.

  Further, the main area sorting unit 854 executes main area sorting processing for each switching cycle of the light emitting unit 112 between the reference state and the comparison state. In the main area dividing process, the pixels divided into the original area pixels by at least one of the first temporary area dividing process and the second temporary area dividing process are divided into the original area pixels, and the other pixels are classified into the original area pixels. This is a process of dividing the original area pixel.

  In the present embodiment, the two types of temporary region segmentation results based on each of the two types of combinations described above are always reflected in the main region segmentation data Y3. The first of the two types of combinations is a combination of two secondary image data strings X1 and X2 corresponding to each of the standard state and the extinguished state. The second of the two types of combinations is a combination of two secondary image data strings X1 and X2 corresponding to each of the standard state and the brightening state.

  Therefore, the original area pixels can be correctly classified regardless of whether the background of the original 90 is a light color close to white or a dark color close to black.

  Further, the extinguishing state and the brightening state are alternately selected as the comparison state. In this case, the state of the light emitting unit 112 is switched between the extinguished state and the brightened state before and after being brought into the standard state. Therefore, although the state of the light emitting unit 112 is switched to three types of states, the number of times of scanning of the image in the standard state in the sub scanning direction R2 is the case where the state of the light emitting unit 112 is switched to two types of states Is equivalent to

  Therefore, when the operation mode signal Md is the open scanning mode, it is not necessary to reduce the moving speed of the image scanning unit 11 to one third of the moving speed in the closed scanning mode. That is, if the moving speed of the image scanning unit 11 is halved of the moving speed in the closed scanning mode, the resolution of the image in the sub-scanning direction R2 is equivalent to that in the normal image reading process in the closed scanning mode. Resolution.

  The replacement unit 855 performs replacement processing for replacing the data of the pixels that have been classified into the non-document area pixels by the main area classification unit in the first image data sequence with one background data. In the present embodiment, the replacement unit 855 performs the replacement process on the secondary image data sequence X2 corresponding to the standard state output from the first delay buffer 851 in synchronization with the synchronization signal Ss.

  For example, it is conceivable that the replacement unit 855 replaces the data of each pixel divided into the area outside the document with data output as an image of white or other arbitrary gradation at the time of image formation. In general, the image forming unit 4 does not have a function of forming a white image. That is, the white image area is an area that is not developed by the image forming unit 4 and is a base area of the recording sheet 9.

  Therefore, the replacement unit 855 replaces the data of each pixel divided into the document outside area with data corresponding to a white image, so that the replacement unit 855 forms an image for each pixel divided into the document outside area. This is synonymous with controlling the image forming unit 4 so as not to be performed.

  The data selection unit 856 receives two data strings, the image data string Xa after the replacement process and the secondary image data string X1 not subjected to the replacement process, and according to the operation mode signal Md output by the MPU 81. Then, one of the two data strings is selected and output.

  When the operation mode signal Md is a signal indicating the open scanning mode, the data selection unit 856 selects and outputs the image data string Xa after the replacement process. On the other hand, when the operation mode signal Md is a signal representing the closed scanning mode, the data selection unit 856 selects and outputs the secondary image data string X1.

  The post-processing unit 857 performs a predetermined adjustment process on the image data string Xb output from the data selection unit 856, and generates a recording image data string Xc that is a data string after the adjustment process. The recording image data sequence Xc generated by the post-processing unit 857 is used by the laser control unit 86 to adjust the amount of laser light in the optical scanning unit 5.

  More specifically, the post-processing unit 857 converts each pixel data corresponding to the amount of light emitted from the linear region in the image data sequence Xb into data representing pixel density. For example, it is conceivable that the data of each pixel in the image data sequence Xb is data of 256 gradations from 0 to 255. In this case, the post-processing unit 857 calculates the pixel density of 256 gradations by subtracting the data of each pixel input from 255 which is the maximum gradation value.

  As described above, the laser control unit 86 adjusts the amount of laser light output from the optical scanning unit 5 in accordance with the density of each pixel indicated by the recording image data sequence Xc output from the image processing unit 85. Accordingly, when the operation mode signal Md is in the open scanning mode, the image forming apparatus 2 responds to the image data string Xa after the replacement process sequentially generated by the image reading apparatus 1 is performed. An image is formed on the recording sheet 9.

  On the other hand, when the operation mode signal Md is in the closed scanning mode, the image forming apparatus 2 forms an image corresponding to the secondary image data string X1 on the recording sheet 9.

  When the image reading apparatus 1 is an apparatus that can read a color image, the image scanning unit 11 may include a plurality of image sensors 114 that detect different colors of light. In this case, the image processing unit 85 includes a plurality of pre-processing units 850, a plurality of first delay buffers 851, a plurality of temporary area partitioning units 852, and a plurality of second delay buffers 853 corresponding to the image data strings of different colors. It is conceivable to include a plurality of main area dividing sections 854, a plurality of replacement sections 855, and a plurality of post-processing sections 857.

  Further, when the image reading apparatus 1 is an apparatus capable of reading a color image, it is conceivable that the image forming apparatus 2 includes a plurality of image forming units 4 corresponding to different color developers. In this case, each of the image forming units 4 transfers an image to an intermediate transfer belt (not shown), and the image on the intermediate transfer belt is transferred to the recording sheet 9.

[Specific examples of image processing results]
Next, an example of a specific two-dimensional image obtained by image processing executed by the image processing apparatus 10 will be described with reference to FIGS. FIG. 5 is a diagram illustrating an example of the document 90. 6 to 8 show various first image data sequences obtained when the document 90 on the document table 13 is scanned in the open scanning mode with the document table cover 12 opened in the image processing apparatus 10. A two-dimensional image synthesized from is shown.

  FIG. 6 is a diagram illustrating an example of a two-dimensional image synthesized from the first image data sequence obtained when the light emitting unit 112 is in the reference state. FIG. 7 is a diagram illustrating an example of a two-dimensional image synthesized from the second image data sequence obtained when the light emitting unit 112 is in the extinguished state. FIG. 8 is a diagram illustrating an example of a two-dimensional image synthesized from the image data sequence Xa after the background replacement process when the background data is data corresponding to black.

  Consider a case in which two originals 90 shown in FIG. 5 are scanned in the open scanning mode in the image processing apparatus 10. One of the two documents 90 is a document in which an opening 900 is partially formed. Further, the background color of each of the two originals 90 shown in FIG. 5 is white.

  When two originals 90 shown in FIG. 5 are scanned in the open scanning mode, a two-dimensional image obtained by synthesizing the first image data sequence corresponding to the reference state of the light emitting unit 112 is, for example, shown in FIG. The image looks like this.

  As shown in FIG. 6, the image when the light emitting unit 112 is in the reference state is an image including two images of the original 90 and an image outside the original. In the example shown in FIG. 6, the image of the outside area of the document includes a noise image Ng including an image of outside light and a shadow image of an object that blocks outside light.

  On the other hand, as shown in FIG. 7, the image when the light emitting unit 112 is in the extinguished state is an image including the shadow image of the two documents 90 and the image of the area outside the document. As shown in FIGS. 6 and 7, the image in the outside area of the document is substantially the same when the light emitting unit 112 is in the reference state and in the extinguished state.

  Then, the image after the pixels in the area outside the document are replaced with black pixels by the background replacement process is an image as shown in FIG. As shown in FIG. 8, according to the image reading apparatus 1, the document area and the document outside area are correctly divided.

  In addition, when the said brightening state is selected as the said comparison state of the said light emission part 112, the image when the said light emission part 112 is the said comparison state differs from the image shown in FIG.

  The image of the original area when the light emitting unit 112 is in the bright state is a brighter image than the image shown in FIG. On the other hand, the image in the area outside the original when the light emitting unit 112 is in the bright state is equivalent to the image shown in FIGS.

  Then, according to the image reading apparatus 1, as shown in FIG. 8, both when the background of the original 90 is a light color such as white and when the background of the original 90 is a dark color such as black. The document area and the outside-document area are correctly classified.

[Second Embodiment]
Next, the image processing unit 85A provided in the image forming apparatus according to the second embodiment of the present invention will be described with reference to FIG. The image processing unit 85A is an application example of the image processing unit 85 of the image processing apparatus 10.

  FIG. 9 is a block diagram of the image processing unit 85A. In FIG. 9, the same components as those shown in FIG. 3 are denoted by the same reference numerals. Hereinafter, differences from the image processing unit 85 in the image processing unit 85A will be described.

  The image processing unit 85A has a configuration in which a rearrangement unit 858 and a data selection unit 859 are added to the configuration of the image processing unit 85.

  In the image processing unit 85A, the rearrangement unit 858 performs rearrangement processing described later on a plurality of recording image data sequences Xc for one page of the recording sheet 9, and outputs page image data Xd obtained thereby. .

  The data selection unit 859 receives the page image data Xd and the page image data Xd not subjected to the rearrangement process, and selects and outputs one of the two data according to the operation mode signal Md output from the MPU 81.

  The rearrangement process generates and outputs page image data Xd from a plurality of page image data Xd obtained for the entire scanning range in the sub-scanning direction R2. The page image data Xd is a two-dimensional image that includes image data in a circumscribed rectangle of the whole pixel divided into the document area pixels by the main area dividing unit 854 in the entire scanning range in the sub-scanning direction R2. It is data.

  For example, the preset position may be the left end of the start end, the center of the start end, or the center of the page. The arrangement position designation information Lr for designating these set positions is set in advance through an operation on the operation display unit 80, and is notified from the MPU 81 to the image processing unit 85A. The MPU 81 executes the arrangement position setting program Pr2 to execute a process for setting the position where the image data in the circumscribed rectangle of the entire pixel divided into the document area pixels is arranged.

  When the left end of the start end is set, the rearrangement unit 858 sets the image data in the circumscribed rectangle of the entire pixel segmented into the document region pixels by the main region segmentation unit 854 to a recording sheet having a preselected size. 9 generates page image data Xd arranged in a rectangular area starting from the left end of the starting end.

  When the center of the starting edge is set, the rearrangement unit 858 records the image data in the circumscribed rectangle of the entire pixel divided into the document area pixels by the main area dividing unit 854 with a recording sheet having a preselected size. 9 generates page image data Xd arranged in the central region in the main scanning direction R1 starting from the starting end.

  When the center of the page is set, the rearrangement unit 858 has the recording sheet 9 of the size selected in advance as the image data in the circumscribed rectangle of the entire pixel divided into the original region pixels by the main region dividing unit 854. The page image data Xd arranged in the central region in the main scanning direction R1 and the sub-scanning direction R2 is generated.

  If the image processing unit 85A is employed, the image of the pixel divided into the document area pixels is automatically rearranged at a desired position in the output image. As a result, the degree of freedom of the output form of the image of the original 90 is increased and the convenience is enhanced.

[Application example]
In the image reading apparatus 1, the main area dividing unit 854 may include a third temporary dividing unit and a sampling unit. The third temporary partition unit executes the main region partitioning process based on the latest temporary region partition data Y1 and the previous temporary region partition data Y2 in synchronization with the shift gate signal Gs. The sampling unit samples and outputs the sorting result output from the third temporary sorting unit every time the synchronization signal Ss is generated.

  When the main area dividing unit 854 includes the third temporary dividing unit and the sampling unit, in the main area dividing process repeatedly executed by the third temporary dividing unit, one of the two consecutive processes This process is an invalid process in which the processing result is not used. In this case, the main area sorting unit 854 substantially executes the main area sorting process for each switching cycle of the light emitting unit 112 between the reference state and the comparison state. In other words, it is sufficient for the main area dividing unit 854 to execute the main area dividing process at least for each switching cycle of the reference state and the comparison state.

  Further, in the image reading apparatus 1, when the operation mode signal Md is in the open scanning mode, the image scanning unit 11 in the sub-scanning direction R2 is more than when the operation mode signal Md is in the closed scanning mode. It is also conceivable to shorten the light amount detection cycle of the linear region. Thereby, it can be avoided that the image resolution in the sub-scanning direction R2 by the image scanning unit 11 in the open scanning mode is reduced to half of the image resolution in the closed scanning mode. Furthermore, it can be avoided that the scanning time of the image scanning unit 11 becomes long.

  It is also conceivable that the processing of the image processing unit 85 shown above is realized by a processor that executes a computer program. For example, it is conceivable that the MPU 81 or another MPU for image processing executes a process equivalent to the process of the image processing unit 85 by executing a program stored in advance in the storage unit 82.

  The image reading apparatus, the image processing apparatus, and the control method for the image reading apparatus according to the present invention can be freely combined within the scope of the invention described in each claim, Alternatively, the embodiment and application examples can be appropriately modified or partly omitted.

1: Image reading device 2: Image forming device 3: Sheet conveying unit 4: Image forming unit 5: Optical scanning unit 6: Fixing unit 8: Control unit 9: Recording sheet 10: Image processing device 11: Image scanning unit 12: Document Table cover 13: Document table 30: Sheet storage unit 31: Sheet delivery unit roller 32: Sheet conveying roller 33: Discharge roller 41: Photoconductor (image carrier)
42: charging unit 43: developing unit 45: transfer unit 47: cleaning unit 61: fixing roller 62: pressure roller 80: operation display unit 81: MPU
82: storage unit 83: scanning control unit 84: light emission control unit 85, 85A: image processing unit 86: laser control unit 87: signal interface 90: document 100: casing 101: recording sheet discharge tray 111: scanning mechanism 112: light emission Unit 113: Optical system 114: Image sensor 121: Document tray 122: Conveying roller 123: Document discharge tray 300: Sheet conveying path 801: Document sensor 802: Cover sensor 850: Pre-processing unit 851: First delay buffer 852: Temporary area Sorting section (first temporary area sorting section, second temporary area sorting section)
853: second delay buffer 854: main area section 855: replacement unit 856: data selection unit 857: post-processing unit 858: rearrangement unit 859: data selection unit 900: aperture Gs: shift gate signal Le: light emission state Lr: Arrangement position designation information Md: operation mode signal Ng: noise image Pr1: operation mode setting program Pr2: arrangement position setting program R1: main scanning direction R2: sub-scanning direction Ss: synchronization signal

Claims (6)

A light emitting unit that emits light toward a document placed on a transparent document table;
The line is obtained by scanning the document table along the sub-scanning direction orthogonal to the main scanning direction while detecting the amount of light emitted from the linear region along the main scanning direction on the document table for each pixel. An image scanning unit capable of executing an image reading process for sequentially outputting an image data sequence corresponding to a detected light amount for each of the pixels in the stripe region;
When the preset operation mode is an open scanning mode corresponding to a state in which the cover of the document table is not closed , the reference state in which the light emitting unit emits light with a predetermined reference light amount and the reference state A process of alternately switching to a different comparison state is performed while alternately selecting a light-off state and a light-enhanced state that emits light with a light quantity larger than the reference state as the comparison state, and the operation mode is the open scanning mode A light emission control unit that changes the state of the light emitting unit to the reference state in a closed scanning mode different from
When the operation mode is the closed scanning mode, when the light emitting unit is in the reference state, the image scanning unit performs the image reading process at a standard scanning speed, and the operation mode is the open scanning mode. A scanning control unit that causes the image scanning unit to execute the image reading process of outputting the image data sequence each time the state of the light emitting unit is switched at a scanning speed that is half the standard scanning speed ;
Each time the first image data sequence that is the image data sequence corresponding to the reference state of the light emitting unit is obtained, the first image data sequence and the first image data sequence are obtained one time before being obtained. Each of the pixels is divided into a document area pixel and a document outside area pixel according to a difference in data of the pixels corresponding to each other in the second image data string that is the image data string corresponding to the comparison state of the light emitting unit. A first temporary area section;
Each time the second image data sequence is obtained, the pixels corresponding to each other in the second image data sequence and the first image data sequence obtained one time before the second image data sequence is obtained. A second temporary area dividing unit that divides each of the pixels into the original area pixel and the outside original area pixel according to a data difference;
The pixels divided into the document region pixels by at least one of the first temporary region partitioning unit and the second temporary region partitioning unit for each switching period of the reference state and the comparison state of the light emitting unit An image reading apparatus comprising: a main area dividing unit that divides pixels into other pixels outside the original area.   Each of the first temporary area section and the second temporary area section has an area where the difference is greater than a predetermined light amount difference continuously for a predetermined number or more in the main scanning direction. 2. The image reading apparatus according to claim 1, wherein the pixel division can be executed in accordance with a first division rule that divides the pixels into the document area pixels and divides the other pixels into the non-document area pixels.   Each of the first temporary area section and the second temporary area section has the linear shape in the pixel that satisfies the document area condition that requires the difference to be larger than a predetermined light amount difference. Execute the pixel division according to a second division rule that divides all the pixels in the range from the pixel closest to the first end of the region to the pixel closest to the second end of the linear region into the original region pixels. The image reading apparatus according to claim 1, which is possible.   4. The image processing apparatus according to claim 1, further comprising: a replacement unit that replaces data of the pixels that are divided into the non-document area pixels by the main area dividing unit in the first image data sequence with one background data. 5. The image reading apparatus according to item.   Rearrangement for generating two-dimensional image data including image data in a circumscribed rectangle of the whole pixel divided into the original region pixels by the main region dividing unit in a predetermined position in the entire scanning range in the sub-scanning direction The image reading apparatus according to claim 1, further comprising a unit. An image reading apparatus according to any one of claims 1 to 5,
An image processing apparatus comprising: an image forming apparatus that forms, on a recording sheet, images corresponding to the plurality of first image data sequences obtained by the image reading apparatus.

Images