JP2022059179A - Reading device, image forming apparatus, and method - Google Patents

Abstract

To provide a reading device, an image forming apparatus, and a method that can detect even a foreign substance with a small output variation.SOLUTION: A reading device of the present invention has: reading means that reads a reading object with a plurality of pixel sensors; movable means that, when the plurality of pixel sensors read a member to be corrected, changes the positions of the pixels for reading the member to be corrected; storage means that stores a plurality of pieces of output data at the reading positions output from the pixels sensors by changing the reading positions of the pixels with the variable means; detection means that detects a foreign substance based on the plurality of pieces of output data; and correction means that corrects an image of the reading object read by the reading means based on output data obtained at a predetermined position for reading the member to be corrected.SELECTED DRAWING: Figure 3

Description

The present invention relates to a reader, an image forming apparatus and a method.

Conventionally, a reading means such as a line sensor has a variation in accuracy in the output data of each pixel sensor of the reading means. The accuracy variation is, for example, the variation in the output light amount of the light source irradiating the reading target, the variation in the sensitivity of the element of each pixel in the reading means, and the SLA (Selfoc® lens array) provided in the reading means. ) Is caused by periodic fluctuations in the amount of incident light in the pixel arrangement direction based on the refractive index distribution. Therefore, in the conventional image reading device, a predetermined density reference member, which is a correction target member, is read by a reading means, and the shading data, which is the reading data, is used to correct the read image to be read.

On the other hand, if the scanned image is corrected using the shading data created with foreign matter such as dirt adhering to the density reference member, the pixels that read the foreign matter will be overcorrected or undercorrected, and vertical streaks will appear in the image. Causes quality defects that enter. Therefore, it is recommended to remove foreign matter from the concentration reference member before creating shading data.

As a technique for detecting a foreign substance on a concentration reference member, for example, Patent Document 1 discloses a foreign substance detection technique for detecting the presence of a foreign substance when the output level of shading data exceeds a predetermined threshold value. Further, Patent Document 2 discloses a technique for determining whether a foreign substance adheres to a concentration reference member or a glass surface based on shading data.

However, in the conventional method, there is a problem that a foreign substance having a large output fluctuation of shading data can be detected, but a foreign substance having a small output fluctuation cannot be detected.

The present invention has been made in view of the above, and an object of the present invention is to provide a reading device, an image forming device, and a method capable of detecting a foreign substance having a small output fluctuation.

In order to solve the above-mentioned problems and achieve the object, the reading device of the present invention includes a reading means for reading a reading target by a plurality of pixel sensors, and the pixels when the plurality of pixel sensors read the correction target member. A movable means for changing the reading position of the correction target member, a storage means for storing a plurality of output data at each reading position output from each pixel sensor by changing the reading position of the pixel by the movable means, and the plurality of outputs. It is characterized by having a detection means for detecting a foreign object based on data and a correction means for correcting an image to be read read by the reading means based on output data obtained at a predetermined reading position of the correction target member. And.

According to the present invention, it is possible to detect a foreign substance having a small output fluctuation.

FIG. 1 is a diagram showing an example of a reading device according to the first embodiment. FIG. 2 is a diagram showing an example of the configuration of a system block of a reader. FIG. 3 is a diagram showing an example of the configuration of the image processing unit. FIG. 4 is an explanatory diagram when dirt is attached to the concentration reference member. FIG. 5 is an explanatory diagram when the concentration reference member is driven in the main scanning direction to shift the reading position. FIG. 6 is an explanatory diagram of shading data when dirt is attached to the glass surface. FIG. 7 is an explanatory diagram of the processing of the preprocessing unit. FIG. 8 is a diagram showing an example of a case where the threshold value is set based on the output level of the pixel value before averaging. FIG. 9 is an explanatory diagram of threshold value setting performed by the foreign matter detection unit. FIG. 10 is a diagram showing an example of the configuration according to the modification 1 of the image processing unit. FIG. 11 is a diagram showing a calculation result in the difference calculation unit. FIG. 12 is an explanatory diagram when a plurality of stains are attached to the concentration reference member and the interval between them is the same as the driving distance of the concentration reference member. FIG. 13 is an explanatory diagram when a plurality of stains are attached to the concentration reference member and the interval between them is the same as the driving distance of the concentration reference member. FIG. 14 is a diagram showing an example of the configuration according to the second modification of the reading device. FIG. 15 is a diagram showing the configuration of an example of the image forming apparatus according to the second embodiment.

Hereinafter, embodiments of a reading device, an image forming device, and a method will be described in detail with reference to the accompanying drawings.

(First Embodiment)
FIG. 1 is a diagram showing an example of a reading device according to the first embodiment. FIG. 1 shows the configuration of a reading device 1 equipped with an ADF (Automatic Document Feeder) as an example of the reading device.

The reading device main body 10 has a contact glass 11 on the upper surface thereof, and has a reading means inside the reading device main body 10. Here, as an example of the reading means, the configuration of the reading means (first reading means) of the reduced optical system method is shown. The first reading means includes a light source 13, a first carriage 14, a second carriage 15, a lens unit 16, a sensor board 17, and the like. In FIG. 1, the first carriage 14 has a light source 13 and a reflection mirror 14-1, and the second carriage 15 has reflection mirrors 15-1 and 15-2.

The reading device main body 10 irradiates the reading target with the light of the light source 13, and the reflected light from the reading target is folded back by the mirror 14-1 of the first carriage 14 and the mirrors 15-1 and 15-2 of the second carriage 15. The image of the object to be read, which is incident on the lens unit 16 and is formed on the light receiving surface on the sensor board 17 from the lens unit 16, is read. The sensor board 17 has a line sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary MOS) as a reading unit, and the image of the reading target formed on the light receiving surface of the line sensor is sequentially converted into an electric signal and read. ..

The reference white plate 12 is a correction target member used for correcting the output image from the line sensor. As an example, the reference white plate 12 uses a white plate concentration reference member. In the present embodiment, the correction target member is provided so as to be movable. The configuration of the member to be corrected will be described in detail later.

The reading device 1 is provided with a control board in the reading device main body 10, and controls each part of the reading device main body 10 and each part of the ADF 20 to read the reading target by a predetermined reading method. The reading target is, for example, a recording medium on which characters or patterns are formed or a recording medium before image formation. Hereinafter, a manuscript (also referred to as a manuscript paper), which is an example of a recording medium, will be described as an example.

The reading device 1 uses the ADF 20 to read the document 100 in a sheet-through manner. In the configuration shown in FIG. 1, the reading device 1 separates the originals from the original bundle of the tray 21 of the ADF 20 one by one by the pickup roller 22 and conveys the original 100 to the transport path 23, and determines the surface to be read of the original 100. The original 100 is ejected to the paper ejection tray 25 by scanning at the reading position of. The document 100 is transported by rotating various transport rollers 24.

To read the document 100, for example, the scanning device 1 moves the first carriage 14 and the second carriage 15 to a predetermined home position and fixes them, and the document 100 has the reading window 19 and the background portion 26 in a fixed state. It is done at the timing of passing between. The reading window 19 is a slit-shaped reading window provided in a part of the contact glass 11, and when the document 100 passes through the reading window 19 by automatic transfer, the sub-scanning direction of the document 100 is scanned. The background portion 26 is a background member having a predetermined background color, which is arranged at a position facing the slit. The reading device 1 transmits the reflected light of the light source 13 irradiating the first surface (for example, the surface) of the document 100 directed toward the reading window 19 while the document 100 passes through the reading window 19 on the sensor board 17. Read sequentially with the line sensor of.

When scanning both sides of the document 100, after passing through the reading window 19, the second surface (back surface) of the document 100 is read by a second scanning means, which is another example of the scanning means. In the reading device 1 shown in FIG. 1, the second surface is read by the reading module 27 provided on the back surface side of the first surface of the document 100 of the transport path 23 provided in the ADF 20. The reading module 27 has an irradiation unit and a contact-type image sensor which is a second reading unit, and the contact-type image sensor reads the reflected light of the light irradiated to the second surface of the document 100. The background member 28 provided so as to face the reading module 27 is configured to be movable. The background member 28 corresponds to the correction target member of the second reading means, and is composed of, for example, a white density reference member.

In the configuration of the reading device 1 of this example, reading by the first reading means is also possible by the flatbed method. Specifically, the ADF 20 is lifted to expose the contact glass 11, and the original 100 is placed directly on the contact glass 11. Then, the ADF 20 is lowered to the original position, and the back surface of the document 100 is pressed by the lower part of the ADF 20. In the flatbed method, since the document 100 is fixed, the carriage (first carriage 14, the second carriage 15) side is moved with respect to the document 100 to perform scanning. The first carriage 14 and the second carriage 15 are driven by a scanner motor and scan the sub-scanning direction of the document 100. For example, the first carriage 14 moves at a speed V, and at the same time, the second carriage 15 moves at a speed of 1 / 2V, which is half the speed of the first carriage 14, so that the first carriage 11 on the contact glass 11 side of the document 100 can be used. Read the face. In this case, the lower part of the ADF 20 (a background member such as white that holds the document 100 from the back) corresponds to the background portion. Further, the reference white plate 12 is read by the line sensor by the movement of the first carriage 14 and the second carriage 15, and is used as a “correction target member”.

In this example, the first carriage 14, the second carriage 15, the lens unit 16, the sensor board 17, and the like are shown separately, but these may be provided individually or may be integrated into an integrated sensor. It may be provided as a module.

Before reading the document 100, the first reading means and the second reading means read the corresponding density reference members and generate shading data, respectively. The shading data is used to correct the accuracy variation for each pixel appearing in the output data from the reading unit, and the first reading means and the second reading means function as the correction means before reading the document 100, for example. It is generated at a predetermined timing such as when the power of the scanning device 1 is turned on, when the power is turned off, immediately before scanning the document 100, or at a predetermined time set in advance, and the latest shading data is used to correct the scanned image of the document 100.

The causes of the accuracy variation for each pixel are, for example, the variation in the output light amount of the light source irradiating the document 100, the variation in the sensitivity of the element of each pixel in the reading unit, and the SLA (selfoc lens) provided for the reading unit. Periodic variation in the amount of incident light in the pixel arrangement direction based on the refractive index distribution of the array) or the like.

However, if foreign matter such as dust or dirt adheres to the concentration reference member, the information on the foreign matter is reflected in the shading data by the pixels that read the foreign matter. When correction is performed with the shading data, the read portion of the foreign matter becomes overcorrected or insufficiently corrected, and the quality of the image deteriorates.

In the present embodiment, when the reading unit reads the density reference member, a plurality of shading data are acquired from the reading unit while changing the reading position of the density reference member by each pixel of the reading unit by the movable means. Then, the foreign matter is detected based on the plurality of shading data, the foreign matter is removed, and then the shading data without the foreign matter is updated. For example, in the case of the first reading means, the first carriage 14 and the second carriage 15 are fixed at the reading position of the reference white plate 12, and the concentration reference member is mainly scanned by a mechanism for reciprocating the concentration reference member in the main scanning direction. Controls the shift to the direction side. The main scanning direction is an orthogonal direction when the transport direction for transporting the document 100 is the sub-scanning direction. Further, in the case of the second reading means, a mechanism for reciprocating the concentration reference member in the main scanning direction orthogonal to the transport direction (secondary scanning direction) of the document 100 with respect to the reading module 27 fixed at a predetermined position. Controls to shift the concentration reference member in the main scanning direction.

For example, the concentration reference member is reciprocated in the main scanning direction by a mechanism that changes the rotational force of the drive motor into a linear motion in the main scanning direction. The concentration reference member may be fixed and the reading module may be moved. Further, a mechanism for relatively moving the concentration reference member and the reading module may be used. In either case, the same effect can be obtained. Further, other movable means may be appropriately applied as long as the reading position on the density reference member by each pixel such as the reading module can be changed regardless of the mechanism for moving the density reference member or the like.

Next, the system configuration of the reading device 1 will be described.
FIG. 2 is a diagram showing an example of the configuration of the system block of the reading device 1. FIG. 2 shows the configuration of system blocks mainly related to the creation of shading data, and some of the other blocks are omitted. As shown in FIG. 2, the reading device 1 includes a control unit 300, an operation panel 301, various sensors 302, a scanner motor 303, various motors 304 in the transport path, a drive motor 305 of a movable means, and a reading means. 306 and included. The reading means 306 shows a typical configuration of a first reading means and a second reading means. The configuration of the first reading means and the second reading means is not limited to the configuration of the reading means 306. Further, although the present embodiment shows that two reading means are provided as an example, the number of reading means may be one or three or more.

The operation panel 301 is an operation panel having operation buttons for operating the reading device 1. Further, as an example of the means for notifying the user, the operation panel 301 includes a display screen, a voice output unit, and the like. The operation panel 301 accepts input operations such as various settings and reading execution from the user with an operation button (may be a touch panel), and transmits the corresponding operation signal to the control unit 300. Further, the operation panel 301 can display various information on the display screen based on the display control signal from the control unit 300, or can output voice based on the notification signal from the control unit 300.

The control unit 300 is a control board that controls each unit of the reading device 1. The control unit 300 has a CPU or the like, and is based on input information from the operation panel 301 and sensor information input from various sensors 302 such as a document position sensor and a document size detection sensor provided in the transport path. , The reading operation of the document 100 is controlled in a predetermined step. For example, the control unit 300 outputs a control signal to the scanner motor 303 to move the first carriage 14 and the second carriage 15 to the reading position of the density reference member or the reading position of the document 100. Further, the control unit 300 outputs a control signal to the drive motor 305 and drives the concentration reference member in the main scanning direction by a movable means (as an example, a reciprocating mechanism).

The reading means 306 is driven by the controller 307 based on a reading control signal (timing signal or the like) output by the control unit 300 to perform a predetermined reading operation. In the example shown in FIG. 2, the reading means 306 includes a light source unit 401, a sensor chip 402, an amplifier 403, an A / D 404, an image processing unit 405, a frame memory 406, an output control circuit 407, and an I /. It has an F circuit 408, and the read image data is output from the output control circuit 407 to the control unit 300 through the I / F circuit 408 for each frame.

For example, the reading means 306 irradiates the document 100 with light by lighting the light source unit 401 based on the lighting signal from the controller 307. Further, the reading means 306 converts the light (reflected light or the like) from the document 100 imaged on each sensor chip 402 into an electric signal and outputs the light. The sensor chip 402 is an example of a pixel sensor. In this example, one sensor chip 402, one amplifier 403, and one A / D404 pair constitute one pixel (pixel circuit), but this is an example, and the pixel configuration is limited to this. It's not something to do.

The reading means 306 amplifies the electric signal (pixel signal) output from each sensor chip 402 by the amplifier 403, converts it from an analog signal to a digital signal by the A / D 404, and outputs it as a pixel level signal (output signal). do. The image processing unit 405 inputs an output signal from each pixel and performs image processing on the obtained digital image data.

The image processing unit 405 is a correction means for correcting the digital image data obtained by reading the document 100. As an example, the image processing unit 405 holds the shading data obtained by reading the density reference member, and performs a process of correcting the digital image data obtained by reading the document 100 with the shading data. Further, when updating the shading data, foreign matter detection processing is performed here. The foreign matter detection process will be described later. The image processing unit 405 stores the frame image after shading correction in the frame memory 406.

Therefore, the reading means 306 transfers the image data of each frame stored in the frame memory 406 to the control unit 300 via the output control circuit 407 and the I / F circuit 408.

FIG. 3 is a diagram showing an example of the configuration of the image processing unit 405. FIG. 3 shows an example of the configuration of the processing unit for detecting foreign matter as an example of the configuration of the image processing unit 405. As shown in FIG. 3, the image processing unit 405 has a shading data memory 601, a pre-processing unit 602, and a foreign matter detecting unit 603 as processing units for detecting foreign matter. Here, the shading data memory 601 corresponds to the "storage means", and the preprocessing unit 602 and the foreign matter detecting unit 603 correspond to the "detecting means".

The shading data memory 601 is a memory for holding a plurality of shading data in which the front stage portion of the image processing unit 405 reads the density reference member 500 at different timings and sequentially outputs the shading data memory 601. For example, at the timing of a first arrangement and the timing of a second arrangement, or at a plurality of preset timings between the first arrangement and the second arrangement including the first arrangement and the second arrangement. Holds all the acquired shading data. The shading data memory 601 has a memory capacity for holding a plurality of shading data that are sequentially output.

The preprocessing unit 602 performs an operation (averaging operation) for averaging a plurality of shading data held by the shading data memory 601.

The foreign matter detecting unit 603 detects the adhesion of foreign matter from the data obtained by the averaging calculation by the preprocessing unit 602.

(Shading correction when there is foreign matter)
FIG. 4 is an explanatory diagram when dirt is attached to the concentration reference member. FIG. 4A shows a concentration reference member 500 to which dirt is attached and a reading means 306 for reading the concentration reference member 500. The reading means 306 and the concentration reference member 500 are in an arrangement relationship in which the positions are fixed to each other (referred to as “first arrangement relationship”) as in the conventional case, and are arranged so as to face each other. It is shown schematically.

In FIG. 4A, a large number of pixel sensors (sensor chips 402) are arranged in the main scanning direction with the light receiving surface facing down on the lower surface of the reading means 306, that is, the surface facing the concentration reference member 500 side. It is assumed that the light receiving surface is covered with glass.

Further, an irradiation unit of the light source 401 that irradiates parallel light rays is arranged so as to correspond to the pixel arrangement. Each pixel sensor reads the reflected light for one line from the density reference member 500 of the parallel light beam irradiated by the irradiation unit. The irradiation unit may be configured as a sensor module together with the pixel sensor, or may be provided separately from the pixel sensor. Here, it is assumed that it is configured as a sensor module for convenience. Further, although the pixel sensor for one row will be described for the sake of clarity, a plurality of rows may be provided in parallel, such as a row for each color of RGB. Further, a plurality of columns in the main scanning direction may be divided.

In FIG. 4A, dirt X is attached to the position of 4000 [px (pixel)] of the density reference member 500. The position of 4000 [px] corresponds to the reading position read by the pixel of the 4000 [px] eye of the reading means 306. When the density reference member 500 is read by the reading means 306 in the first arrangement, when the reading resolution is 600 dpi, the output data of the pixel values in the main scanning direction shows the characteristics as shown in FIG. 4 (b), for example.

The characteristic data f in FIG. 4B is output data when the horizontal axis is the main scanning position and the vertical axis is the pixel value (gradation value), and the pixel values include variations at each main scanning position. ing. This characteristic data f corresponds to the shading data at the time of the first arrangement. Since the pixel value is lightness or luminance, it is a large value for bright pixels and a small value for dark pixels. In FIG. 4B, since the value at the position where the main scanning position is 4000 dpi is the position where the dirt X is read, the value is prominently smaller than the pixel values at the main scanning positions before and after that, that is, a dark value is shown.

In the example shown in FIG. 4B, since the white density reference member 500 is read, the pixel value is as large as 220 [digit] at the position where there is no stain X, but the stain X is attached to 4000. At the position of [px], the pixel value is reduced to 40 [digit].

FIG. 5 is an explanatory diagram when the concentration reference member 500 is driven in the main scanning direction to shift the reading position. FIG. 5A shows an arrangement (referred to as “second arrangement”) of the reading means 306 and the concentration reference member 500 after the concentration reference member 500 is driven by +2 mm in the main scanning direction, that is, is moved by the movable means. ing. FIG. 5B is output data (characteristic data) of pixel values in the main scanning direction when the density reference member 500 is read by the reading means 306 in the second arrangement.

As shown in FIG. 5A, by driving the density reference member 500 by + 2 mm in the main scanning direction, each reading position on the density reference member 500 read by each pixel sensor of the reading means 306 is in the main scanning direction. The deviation is +47 [px], and the stain X also moves to the pixel position of 4047 [px]. From this, as shown in FIG. 5B, the characteristic data f has the same overall characteristics, but the output of reading the stain X moves to the position of 4047 [px].

FIG. 6 is an explanatory diagram of shading data when dirt is attached to the glass surface. Here, the glass surface is assumed to be glass that covers the light receiving surface of the reading means 306, but the optical path of light between the light source unit 401 and the light receiving surface of the reading means 306 that receives light from the concentration reference member. Members provided inside are also included. For example, the contact glass 11, the reading window, the lens surface, and the like may be included.

As shown in FIG. 6A, since the dirt Y is attached to the position of 4000 [px] on the glass surface in the first arrangement, the pixel value at the position where the main scanning position is 4000 [px] is the pixel value. The value is prominently smaller than the pixel values of the front and rear main scanning positions, that is, it is a dark value. On the other hand, as shown in FIG. 6B, even after the density reference member 500 is driven, the position of the glass surface with respect to each pixel of the reading means 306 does not change, so that the pixel for reading the stain Y remains the same. .. That is, when dirt is detected, it can be seen that the position of dirt can also be detected by examining the change in the pixel position before and after driving.

FIG. 7 is an explanatory diagram of the processing of the preprocessing unit 602. FIG. 7A shows the arrangement of the concentration reference member 500 and the reading means 306 when the concentration reference member 500 is driven, and the concentration reference member 500 as an explanatory diagram when dirt X is attached to the concentration reference member 500. The figure which arranged the shading data acquired in the predetermined line period in the drive period in the vertical axis direction is shown. Further, as an explanatory diagram in the case where the dirt Y is attached to the glass surface in FIG. 7B, the arrangement of the concentration reference member 500 and the reading means 306 when the concentration reference member 500 is driven, and the arrangement of the concentration reference member 500 and the concentration reference member 500. The figure which arranged the shading data acquired in the predetermined line period in the drive period in the vertical axis direction is shown. The shading data at each timing arranged in the vertical axis direction is held in the shading data memory 601.

As shown in both FIGS. 7 (a) and 7 (b), the movable concentration reference member 500 is driven in the main scanning direction with respect to the reading means 306 having a fixed position. In this example, it is driven by + 2 mm. Shading data is acquired in a predetermined line cycle during this drive period, and an averaging calculation is performed for all the acquired shading data (data held in the shading data memory 601) for each main scanning position.

As shown in FIG. 7A, when the stain X is attached to the density reference member 500, the pixel value of the main scan position where the stain X is read continuously moves to another main scan position. .. Further, as shown in FIG. 7B, when the stain Y is attached to the glass surface, the pixel value of the main scanning position where the stain Y is read always appears at the same main scanning position, so that after averaging. The position of dirt can also be detected from the data.

The averaged data is generated, for example, by adding a plurality of shading data in pixel units and averaging them in pixel units. This compresses the vibration of noise other than foreign matter in the characteristic data. Specifically, the line counter adds the pixel values for each pixel in the vertical axis direction of the characteristic data of FIG. 7, and calculates the average value of each pixel.

8 and 9 are diagrams illustrating a method of setting a threshold value of the foreign matter detection unit 603. Both FIGS. 8 and 9 show an example of the output level of the pixel values before and after averaging. FIG. 8 shows an example in which the threshold value is set based on the output level of the pixel value before averaging. As shown in FIG. 8, before averaging, the output level fluctuates greatly due to uneven illuminance of the light source and uneven density of the density reference member. If the threshold value is set based on the output level before averaging without performing averaging as it is, the threshold value A is obtained by further reducing the noise margin φ from the lower limit of the output level, so that the threshold value A becomes low. The threshold value for detecting foreign matter is a value obtained by setting a noise margin φ, which is determined in advance by a statistical method so as not to pick up noise, with reference to a lower limit of noise.

However, when a foreign substance having a small output fluctuation of, for example, about 150 [digit] is detected, it is not detected at the threshold value A (140 [digit]). Foreign matter with a small output fluctuation cannot cross the threshold value A and is not detected.

FIG. 9 is an explanatory diagram of threshold value setting performed by the foreign matter detection unit 603. As shown in FIG. 9, in the threshold value setting method performed by the foreign matter detection unit 603, it is possible to reduce the output fluctuation caused by the density unevenness of the concentration reference member after averaging as shown in FIG. 9, and the output level thereof can be reduced. The noise margin φ can be taken from the lower limit. Therefore, even a foreign substance having a small output fluctuation of about 150 [digit] can be detected. That is, according to the detection method of the present embodiment, the detection accuracy of foreign matter is improved, and foreign matter having a small output fluctuation can be detected.

The shape and arrangement of the concentration reference member shown in this embodiment is an example. Any shape and arrangement that can be read by the reading means may be appropriately changed. For example, a plate-shaped member is shown as a concentration reference member, but the same effect can be obtained by using, for example, a roller member that can be driven in the main scanning direction.

Further, in the present embodiment, the image processing unit of the reading means is provided with means for shading correction and foreign matter detection, but the control unit may be modified to perform shading correction and foreign matter detection.

(Modification 1)
In the reading device according to the first embodiment, a configuration is shown in which a detection result of the presence of a foreign substance can be obtained when a foreign substance is present including a device having a small output fluctuation. When the reading device according to the first embodiment is used and the result with foreign matter is obtained, the user removes the foreign matter by cleaning the concentration reference member or the glass surface. However, it is not known in detail whether the foreign matter is present on the concentration reference member or on the glass surface. Therefore, as a modification 1 of the reading device, the configuration of the image processing unit 405 for obtaining the detection result indicating whether the foreign matter is present on the concentration reference member or on the glass surface is shown.

FIG. 10 is a diagram showing an example of the configuration according to the modification 1 of the image processing unit 405. As shown in FIG. 10, the image processing unit 405 according to the modification 1 further includes a difference calculation unit 604 and an attachment position determination unit 605 in the configuration of the image processing unit 405 according to the first embodiment (see FIG. 3). include. Here, the difference calculation unit 604 and the attachment position determination unit 605 correspond to the "determination means".

The difference calculation unit 604 and the adhesion position determination unit 605 operate when the foreign matter is detected by the foreign matter detection unit 603, and determine whether the foreign matter is attached to the concentration reference member or the glass surface.

As an example, the difference calculation unit 604 averages the shading data of a predetermined number of two lines among the plurality of shading data held in the shading data memory 601 by the preprocessing unit 602 (SH data). Difference calculation (SH data 1-SH data 2) is performed using 1 and SH data 2). Here, the SH data 1 corresponds to the shading data acquired before the concentration reference member is driven as an example, and the SH data 2 corresponds to the shading data acquired after the concentration reference member is driven. The adhesion position determination unit 605 determines the adhesion position of the foreign matter from the calculation result of the difference calculation unit 604. The operations of the difference calculation unit 604 and the adhesion position determination unit 605 will be described in more detail with reference to FIGS. 11 to 13.

FIG. 11 is a diagram showing a calculation result in the difference calculation unit 604. FIG. 11A shows the difference calculation result between SH data 1 and SH data 2 when dirt adheres to the concentration reference member, and FIG. 11B shows SH when dirt adheres to the glass surface. The difference calculation result of the data 1 and the SH data 2 is shown.

From FIGS. 11 (a) and 11 (b), paying attention to 4000 [px] in which dirt was attached before driving the concentration reference member, it depends on whether the position where the dirt is attached is on the concentration reference member or on the glass surface. It can be seen that the results of each calculation are different. That is, as shown in FIG. 11A, when dirt adheres to the concentration reference member, the pixel that detects the dirt after driving also changes to 4047 [px], and the difference becomes +180 [digit] at 4000 [px]. If dirt is attached to the glass surface, there is no movement between pixels, so the difference is 0 [digit].

Therefore, by inputting the calculation result of the pixel (4000 [px] in this example) to which the stain was attached before driving the density reference member into the determination formula, it is possible that the stain is attached to the density reference member on the glass surface. It is possible to determine whether or not it is attached to.

The following equations (1) and (2) are examples of determination equations in which the adhesion position determination unit 605 makes a determination. The adhesion position determination unit 605 compares the absolute values of the calculation results of the SH data 1 and the SH data 2 output by the difference calculation unit 604 with a predetermined threshold value (pixel level), and when the equation (1) is satisfied, the density reference member. It is determined that dirt is attached to the glass surface, and when the formula (2) is satisfied, it is determined that dirt is attached to the glass surface. Here, 15 [digit] is shown as an example of the threshold value, but the present invention is not limited to this, and any value may be appropriately changed as long as the dirt adhesion position is a value that can be separated between the glass surface and the concentration reference member.

| SH data 1-SH data 2 |> 15 [digit] ... Equation (1)
| SH data 1-SH data 2 | ≤15 [digit] ... Equation (2)

If there are a plurality of stains on the concentration reference member and the interval between them is the same as the driving distance of the concentration reference member, the detection is performed as follows.

12 and 13 are explanatory views when a plurality of stains are attached to the concentration reference member and the interval thereof is the same as the driving distance of the concentration reference member. 12 (a) and 12 (b) show shading data obtained before and after driving, respectively.

As shown in FIGS. 12 (a) and 12 (b), the dirt X1 and the dirt X2 are attached at the same distance +2 mm (corresponding to 47 [px]) as the driving distance of the concentration reference member +2 mm. Therefore, even in the shading data after the drive of the concentration reference member shown in FIG. 12B, the stain X2 at the position of 4000 [px] before the drive is 40 [px] at the position of 4000 [px] as well as the stain X2 of 40 [digit]. Dirt X1 of] is detected.

FIG. 13 is a difference calculation result between SH data 1 and SH data 2 when a plurality of stains are attached to the density reference member and the interval is the same as the driving distance of the density reference member. As shown in FIG. 13, when focusing on 4000 [px], the calculation result becomes 0 [digit], but when focusing on 3053 [px], the calculation result becomes +180 [digit]. Therefore, even if the calculation result is 0 at 4000 [px], it is attached to the concentration reference member by determining whether dirt is attached to any of the pixels, such as 3053 [px] in this example. It is possible to judge that.

Since the processing is performed by the difference calculation unit 604, the calculation processing of the difference calculation has been described here. It may be carried out as a process.

(Modification 2)
When a foreign substance is detected according to the first embodiment or the configuration of the first modification, it is conceivable to stop the operation of the reading device or notify the user of the detection of the foreign substance. Therefore, as a modification 2 of the reading device, a configuration for notifying the user of the detection of a foreign substance is shown.

FIG. 14 is a diagram showing an example of the configuration according to the second modification of the reading device 1. As shown in FIG. 14, a notification unit 700 is further provided in the configuration of the modified example 1 (see FIG. 10). Here, the notification unit 700 corresponds to the "notification means".

When the notification unit 700 detects a foreign object, the notification unit 700 notifies the user of the presence of the foreign substance. In this example, since the notification unit 700 can detect the adhesion position up to the adhesion position by the adhesion position determination unit 605, the notification unit 700 notifies the user of the adhesion position based on the determination result of the adhesion position determination unit 605. If the configuration does not have the adhesion position determination unit 605 as shown in the first embodiment, the notification unit 700 notifies the user of the presence of the foreign matter on condition that the foreign matter detection unit 603 detects the foreign matter. You may.

The notification unit 700 outputs information indicating the presence or position of a foreign substance to the operation panel 301 to display the presence or position of the foreign substance on the display screen of the operation panel 301 or output voice by the voice output unit. It is possible.

(Modification 3)
The concentration reference member may be a rotating member. In this case, the reading device drives the concentration reference member in the forward rotation direction or the reverse rotation direction, and changes the reading position in the rotation direction on the rotation surface of the concentration reference member. If the foreign matter is short in the vertical direction, that is, the foreign matter is short in the rotation direction of the concentration reference member, a region without foreign matter appears if the reading position is changed in the rotation direction. The pixel value changes and foreign matter can be detected. In particular, the effect is maximized when the attached foreign matter has a width equivalent to the driving distance of the concentration reference member.

On the contrary, when the foreign matter is sufficiently small with respect to the driving distance, the foreign matter is also made uniform by averaging the acquired shading data of a plurality of lines, and the accuracy of foreign matter detection is reduced. Therefore, by providing a configuration that can be driven also in the sub-scanning direction, even if the foreign matter has a narrow width in the main scanning direction, the foreign matter having a width in the sub-scanning direction can be detected with high accuracy.

(Second embodiment)
FIG. 15 is a diagram showing the configuration of an example of the image forming apparatus according to the second embodiment. The image forming apparatus 2 shown in FIG. 15 is an image forming apparatus generally referred to as a multifunction device (MFP), which has at least two functions of a copy function, a printer function, a scanner function, and a facsimile function.

The image forming apparatus 2 has a reading apparatus 1, and the image of the original document 100 read by the reading apparatus 1 is printed on the recording paper by the image forming unit 80 at the lower part of the reading apparatus 1. Here, the image forming unit 80 corresponds to the “image forming means”.

Specifically, the image forming unit 80 includes an optical writing device 81, a tandem image forming unit (Y, M, C, K) 82, an intermediate transfer belt 83, a secondary transfer belt 84, and the like. The optical writing device 81 writes an image on the photoconductor drum 820 of the image forming unit 82 based on the image corrected by the reading device 1, and the toner image is transferred from each photoconductor drum 820 onto the intermediate transfer belt 83.

In the example shown in FIG. 15, the image forming unit (Y, M, C, K) 82 has four rotatable photoconductor drums (Y, M, C, K) 820, and each photoconductor drum 820 has four rotatable photoconductor drums (Y, M, C, K) 820. Surroundingly, each image forming element including a charging roller, a developer, a primary transfer roller, a cleaner unit, and a static eliminator is provided. By operating each image forming element around each photoconductor drum 820 in a predetermined image forming process, an image is formed on each photoconductor drum 820, and the image formed on each photoconductor drum 820 is a primary transfer roller. Is transferred as a toner image on the intermediate transfer belt 83.

The intermediate transfer belt 83 is arranged on the nip between each photoconductor drum 820 and each primary transfer roller by being stretched by a driving roller and a driven roller. The toner image primaryly transferred to the intermediate transfer belt 83 is secondarily transferred to the recording paper on the secondary transfer belt 84 by the secondary transfer device by running the intermediate transfer belt 83. The recording paper is conveyed to the fixing device 85 by the running of the secondary transfer belt 84, and the toner image is fixed on the recording paper as a color image. After that, the recording paper is ejected to the output tray outside the machine.

As for the recording paper, for example, the paper feed unit 90 feeds out the predetermined recording paper from the paper feed cassettes 91 and 92 for storing the recording papers having different paper sizes, and conveys the recording paper by the conveying means 93 including various rollers for secondary transfer. Supply to the belt 84.

The image forming unit 80 is not limited to the one that forms an image by the electrophotographic method as described above, and may be one that forms an image by an inkjet method.

Although the embodiments and modifications of the present invention have been described above, the embodiments and modifications are presented as examples and are not intended to limit the scope of the invention. These novel embodiments and modifications can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalent scope thereof.

1 Reading device 306 Reading means 405 Image processing unit 601 Shading data memory 602 Preprocessing unit 603 Foreign matter detection unit

Japanese Unexamined Patent Publication No. 2018-12147 Japanese Unexamined Patent Publication No. 2018-07886

Claims (8)

A reading means that reads the reading target by a plurality of pixel sensors,
A movable means that changes the reading position of the correction target member by the pixels when the plurality of pixel sensors read the correction target member.
A storage means for storing a plurality of output data at each reading position output from each pixel sensor by changing the reading position of the pixel by the movable means.
A detection means for detecting a foreign substance based on the plurality of output data,
A correction means for correcting an image to be read read by the reading means based on output data obtained at a predetermined reading position of the correction target member, and a correction means.
A reader characterized by having. The detection means detects foreign matter by setting a threshold value after averaging the plurality of output data.
The reading device according to claim 1. moreover,
The detection means has a determination means for determining the adhesion position of the foreign matter when the foreign matter is detected.
The determination means determines whether or not the foreign matter is attached to the correction target member from the difference between the two output data of the storage means.
The reading device according to claim 1 or 2. moreover,
The detection means has a notification means for notifying the user when a foreign substance is detected.
The reading device according to any one of claims 1 to 3. The notification means is
Notify the adhesion position based on the determination result by the determination means.
The reading device according to claim 4. The movable means changes the reading position of the correction target member by the pixels by moving the correction target member in the main scanning direction in which a plurality of pixel sensors are arranged or in a direction orthogonal to the main scanning direction.
The reading device according to any one of claims 1 to 5. The reading device according to any one of claims 1 to 6.
An image forming means for forming an image on a recording paper based on the corrected image data output by the reading device, and an image forming means.
An image forming apparatus characterized by having. This method is performed by a reader having a storage unit.
A movable step that changes the reading position of the correction target member by the pixels when a plurality of pixel sensors read the correction target member.
A storage step of storing a plurality of output data at each reading position output from each pixel sensor by changing the reading position of the pixel in the storage unit, and a storage step.
A detection step for detecting a foreign substance based on the plurality of output data,
A reading step of reading the reading target by the plurality of pixel sensors,
A correction step of correcting the image to be read based on output data obtained at a predetermined reading position of the member to be corrected, and a correction step.
How to include.

Images