JP6885078B2 - Image reader, image forming device, image processing device, and image processing method - Google Patents

Description

The present invention relates to an image reading device, an image forming device, an image processing device, and an image processing method.

Conventionally, in an image reader, shading data is used to correct variations in the amount of illumination light incident on a photoelectric conversion element in the main scanning direction, manufacturing variations in each pixel circuit of the photoelectric conversion element, and the like. The shading data is obtained by reading the density reference member, which is the reference white portion, by the photoelectric conversion element in the entire main scanning direction, and the reading image is subtracted to correct the above variation. If foreign matter such as dirt adheres to parts (density reference member, contact glass, etc.) on the optical path of the illumination light when reading the density reference member, a foreign matter signal is added to the shading data and the value is corrected to an appropriate value. Not done. Therefore, as one of the measures for eliminating the foreign matter signal, there is a method in which a movable mechanism is provided in the concentration reference member.

In contact image sensors (CIS), etc., it is often provided in a small space inside the ADF (Auto Document Feeder) device, and if a movable mechanism is provided in the concentration reference member, the ADF device becomes complicated. It leads to large size and high cost. Therefore, a foreign matter detection technique for detecting foreign matter such as dirt from shading data of a concentration reference member is disclosed. For example, when the output level in the main scanning direction exceeds a predetermined range in the shading data, it is determined that foreign matter is contained (see Patent Document 1).

However, the output level from each pixel circuit of the photoelectric conversion elements arranged in the main scanning direction is not constant due to the influence of the configuration and arrangement of the optical lens that forms the light. For example, at the output level from each pixel circuit, an output pattern of a waveform in which high-frequency components and low-frequency components are mixed appears in the main scanning direction. The conventional foreign matter detection technique has a problem that the foreign matter detection accuracy is low because it is not possible to detect a foreign matter signal buried in the fluctuation width of the output level in the entire main scanning direction.

The present invention has been made in view of the above, and an object of the present invention is to provide an image reading device, an image forming device, an image processing device, and an image processing method having improved detection accuracy of foreign matter.

In order to solve the above-mentioned problems and achieve the object, the image reading device of the present invention forms an image of the density reference member, the light source that irradiates the density reference member with light, and the light from the density reference member. and the predetermined pitch lenses, a plurality of pixel circuits for converting an imaging light into electrical signals by the lens, and a data processing means for generating shading data from the output value of each pixel circuit, the shading data or al the resulting extraction means for extracting foreign matter, have a, and output means for outputting information indicating that the condition that foreign matter exists that the foreign matter is extracted, the extraction means, the moving average from the shading data From the data string of the moving average result, the foreign matter whose difference of the moving average result is out of the normal range is extracted, and further, the high frequency component is shown from the data string showing the high frequency component after removing the low frequency component from the shading data. Foreign matter outside the normal range determined by the maximum and minimum values of the amplitude of is extracted .

According to the present invention, there is an effect that the detection accuracy of foreign matter is improved.

FIG. 1 is a diagram showing an example of the configuration of the image forming apparatus according to the embodiment. FIG. 2 is a cross-sectional view showing an example of a specific configuration of the ADF. FIG. 3 is a diagram showing an example of the hardware configuration of the control unit. FIG. 4 is a diagram showing an example of the arrangement relationship between the second fixed reading unit and the concentration reference member. FIG. 5 is a diagram showing an example of the configuration of the control block of the second fixed reading unit. FIG. 6 is a diagram showing an example of a block configuration of a digital image processing circuit. FIG. 7 is a diagram showing an example of a processing procedure of the white correction processing block. FIG. 8 is a diagram showing an example of the configuration of the detailed block of the foreign matter determination processing block of the first embodiment. FIG. 9 is an explanatory diagram of the foreign matter determination process. FIG. 10 is an explanatory diagram of a smoothing unit with a moving average. FIG. 11 is a diagram showing a correspondence relationship between the pixel number output by the smoothing unit and the pixel number of the determination unit 402. FIG. 12 is an explanatory diagram of the foreign matter determination process of the second embodiment. FIG. 13 is a diagram showing an example of the configuration of the detailed block of the foreign matter determination processing block. FIG. 14 is a diagram showing an example of the processing flow of the detailed block. FIG. 15 is an explanatory diagram of a method of calculating the maximum value and the minimum value by the amplitude estimation unit. FIG. 16 is a diagram showing an example of the correspondence between the pixel number of the high frequency component output pattern data and the pixel number of the average value of the maximum value max and the minimum value min. FIG. 17 is an explanatory diagram of the determination process of the determination unit. FIG. 18 is a diagram showing an example of a state in which the rod lens is displaced from the sensor and the rod lens when the rod lens is arranged in the image sensor in a bent state according to the third embodiment. FIG. 19 is a diagram showing an example of a high frequency component output pattern of data obtained by removing low frequency components from shading data. FIG. 20 is a diagram conceptually showing the division into N blocks and the setting of the threshold value for each block performed by the amplitude estimation unit. FIG. 21 is an explanatory diagram of the fourth embodiment. FIG. 22 is a diagram showing an example of the configuration of the detailed block of the foreign matter determination processing block of the fifth embodiment.

(Embodiment)
Hereinafter, embodiments of an image reading device, an image forming device, an image processing device, and an image processing method will be described in detail with reference to the accompanying drawings. In the following, an example of application to the above-mentioned "image forming apparatus" as the above-mentioned "image reading device" will be shown.

FIG. 1 is a diagram showing an example of the configuration of the image forming apparatus according to the embodiment. In FIG. 1, the image forming apparatus 1 is configured as a multifunction device that can use a printer function, a scanner function, and a copy function.

In FIG. 1, the image forming apparatus 1 includes an image reading unit 10 as the “image reading apparatus”, a recording paper supply unit 20, and an image forming unit 30. Further, the image forming apparatus 1 is provided with an operation panel (not shown) on the upper part of the housing.

The operation panel is, for example, a display input device in which a touch panel is superposed on a liquid crystal display, and an operation instruction (for example, reading start) of an image reading unit 10, a recording paper supply unit 20, an image forming unit 30 or the like by a user is used. Accept instructions, etc.).

The image scanning unit 10 has a scanner 10a and an automatic document transfer device (hereinafter referred to as ADF (Auto Document Feeder)) 10b arranged on a contact glass 11 on the upper surface of the scanner 10a, and the document set in the ADF 10b. It has a scanning method in which a document is read by a fixed scanning unit while being conveyed at a predetermined speed.

The ADF 10b has a document mounting table 12 for mounting a document bundle before scanning and a document stacking table 13 for stacking a stack of documents after scanning on the main body cover. Inside the main body of the ADF 10b, there is a document transport path 14 for ejecting a document from the document mounting table 12 through the contact glass 11 to the document stack table 13. The ADF 10b is fixed to the scanner 10a with a hinge so as to be openable and closable, and when the ADF 10b is opened, the contact glass 11 on the upper surface of the scanner 10a is exposed, and the document placed on the contact glass 11 can be read.

The scanner 10a has a first fixed reading unit 15 below the contact glass 11, and the ADF 10b has a second fixed reading unit 16 along the document transport path 14. The image scanning unit 10 transports the document through the document transport path 14, and the first fixed scanning unit 15 reads the first surface (front surface) of the document. Subsequently, the image reading unit 10 reads the second surface (back surface) of the document with the second fixed reading unit 16.

FIG. 2 is a cross-sectional view showing an example of a specific configuration of the ADF 10b. The configuration of the ADF10b and its operation will be described with reference to FIG.

The ADF10b includes a document set unit A, a separation transfer unit B, a resist unit C, a turn unit D, a first reading transfer unit E, a second reading transfer unit F, and a paper ejection along the document transfer path 14. It has a unit G and a stack unit H.

The document setting unit A mainly has a component that stands by the document bundle MS in the transport start state. The separation and transfer unit B mainly has a component that separates and feeds the originals one by one from the original bundle MS in the standby state on the original mounting table 12. The resist unit C mainly has a component that temporarily abuts the document fed from the separation and transport unit B to align the document, and then sends out the document. The turn unit D mainly has a C-shaped curved transport path included in the document transport path 14, and the front and back sides of the document are reversed when the document passes through the curved transport path. The first reading / conveying unit E mainly has a component that reads the first surface (surface) of the document. The second reading / conveying unit F mainly has a component that reads the second surface (back surface) of the document. The paper ejection unit G mainly has a component for ejecting the scanned document toward the stack unit H. The stack unit H mainly has a document stack base 13 for stacking documents after being read.

Specifically, the document set unit A is composed of a document mounting table 12, a set filler 42, a pickup roller 43, and the like. The document mounting table 12 includes a movable document table 40 that supports the front end side of the document bundle MS, and a fixed document table 41 that supports the rear end side of the document bundle MS.

On the fixed document table 41, document length sensors 60 for detecting the length of the document bundle MS in the transport direction are arranged at predetermined intervals. The document length sensor 60 determines the approximate length of the document bundle MS in the transport direction. As the document length sensor 60, a reflective photo sensor, an actuator type sensor that can detect even one document, and the like are used.

Further, the fixed document table 41 has side guides (not shown) at both ends in a direction (width direction) orthogonal to the transport direction of the document bundle MS, and the fixed document table 41 is abutted against the document bundle MS to cause the document bundle MS. Positioning in the width direction is done.

The movable document table 40 is provided by a cam mechanism so as to be vertically movable in the directions of arrows a and b in the drawing. Further, a set filler 42, which is a lever member, is provided above the movable document table 40 so as to be swingable. When the document bundle MS is set on the document mounting table 12 so that the first side of the document faces upward, the document bundle MS pushes up the set filler 42, and the document set sensor 61 detects the set of the document bundle MS. Then, the movable document table 40 is raised so that the uppermost surface of the document bundle MS comes into contact with the pickup roller 43.

A pickup roller 43 is provided above the movable document table 40. The pickup roller 43 can be operated in the directions of arrows c and d in the figure by the cam mechanism. The pickup roller 43 is pushed up by the upper surface of the document bundle MS in the direction of arrow c in the drawing as the movable document table 40 rises. The ascending of the movable document table 40 is stopped when the table ascending sensor 62 detects the upper limit.

When the scanning start key on the operation panel is pressed, the pickup roller 43 rotates in the direction of transporting the top-level document of the document bundle MS to the paper feed port 44, and picks up one to several sheets from the top-level document. .. One to several originals picked up enter the separation / transport unit B and are fed between the paper feed belt 45 and the reverse roller 46.

The paper feed belt 45 is stretched by a drive roller 47 and a driven roller 48, and moves endlessly in the paper feed direction. The reverse roller 46 comes into contact with the lower surface of the paper feed belt 45 and rotates in the direction opposite to the paper feed direction. As a result, the top-level document and the document below it are separated, and only the top-level document is fed.

The manuscript separated into one sheet enters the resist unit C. The original is fed first by the paper feed belt 45, and the tip is detected by the abutting sensor 63. Then, the pickup roller 43 is retracted from the upper surface of the document, and the document is fed only by the conveying force of the paper feed belt 45. The tip of the document enters the nip of the upper and lower rollers of the pull-out roller 49, and the tip is aligned (skew correction).

The pull-out roller 49 has a skew correction function, and sends the skew-corrected document to the intermediate roller 50. The sent document passes through the document width sensor 64.

The document width sensor 64 is a sensor in which a plurality of paper detection sensors made of a reflective photo sensor or the like are arranged in the width direction of the document, and detects the size of the document in the width direction. On the other hand, the size in the length direction (conveyance direction) of the document is detected by the abutting sensor 63 detecting the passage of the rear end of the document and counting the motor pulses from the detection of the tip of the document.

The document is conveyed by the pull-out roller 49 and the intermediate roller 50 and enters the turn unit D. The entered document passes through the curved transport path by the intermediate roller 50 and the reading inlet roller 51, and the front and back sides are reversed.

When the tip of the document is detected by the reading inlet sensor 65, the feeding speed of the document is reduced before the tip of the document enters the nip of the pair of upper and lower rollers of the reading inlet roller 51. Further, when the document enters the first scanning and transporting unit E and the tip of the document is detected by the resist sensor 66, the document transport is temporarily stopped before the first scanning position 52 of the first fixed scanning unit 15. To do.

After that, when the start of scanning is permitted, the transport is started, and the first surface of the document is read by the first fixed reading unit 15 while the document passes through the first scanning position 52 at a predetermined transport speed.

After passing through the first reading and transporting unit E, the document passes through the second reading and transporting unit F at a predetermined speed. When reading both sides (first side and second side) of the document, the tip of the document is detected by the paper ejection sensor 67. Then, the second surface of the document is read by the second fixed reading unit 16 while the document passes through the second reading position 53.

The second fixed reading unit 16 is, for example, a contact image sensor (CIS). A density reference member 54 is provided at a position facing the transfer path through which the document at the second reading position 53 passes.

After passing through the second reading / conveying unit F, the original is conveyed to the paper ejection unit G, and the rotation of the paper ejection roller 55 causes the original to escape from the nip of the roller pair of the paper ejection roller 55 to the original stack base 13 of the stack unit H. The paper is ejected.

Returning to FIG. 1, the remaining parts will be described. The recording paper supply unit 20 is fed by two recording paper paper feed cassettes 21 and 22 arranged in multiple stages, a recording paper feeding roller 23 for feeding the recording paper as a recording body from the recording paper paper feed cassettes 21 and 22. It has a recording paper separation roller 25 that separates the recording paper and supplies it to the recording paper supply path 24.

The recording paper supplied to the recording paper supply path 24 enters the image forming unit 30 from the recording paper supply unit 20 and is sent to the secondary transfer device 36 via the resist roller.

The image forming unit 30 mainly includes an optical writing device 31, a tandem image forming unit 32Y, 32M, 32C, 32K, an intermediate transfer belt 35, and a fixing device 37, and is a liquid (example) on a recording paper. Toner is used as a toner) to form an image.

Specifically, the image-forming units 32Y, 32M, 32C, and 32K have four photoconductor drums 33 of yellow (Y), magenta (M), cyan (C), and black (K), respectively. It is provided side by side so as to be rotatable clockwise, and an image forming element including a charging roller, a developing device, a primary transfer roller 34, a cleaner unit, and a static eliminator is provided around each photoconductor drum 33.

The intermediate transfer belt 35 is arranged on the nip between each photoconductor drum 33 and each primary transfer roller 34 by being stretched by a driving roller and a driven roller.

The image forming unit 30 having this configuration charges the surface of each photoconductor drum 33 with a charger, and irradiates, for example, laser light from the optical writing device 31 toward the surface of each charged photoconductor drum 33. By irradiating the laser beam, an electrostatic latent image is formed on the surface of each photoconductor drum 33. Subsequently, the image forming unit 30 supplies the toner of the corresponding color from the developing device toward each photoconductor drum 33 to develop the electrostatic latent image.

Further, the image forming unit 30 primary transfers the developed toner images of each color on the surface of each photoconductor drum 33 to the intermediate transfer belt 35 traveling clockwise in the figure by the primary transfer roller 34. Subsequently, the image forming unit 30 secondarily transfers the primary transferred toner image on the intermediate transfer belt 35 to the recording paper conveyed to the position by the secondary transfer device 36. After that, the image forming unit 30 conveys the recording paper on which the toner image is transferred to the fixing device 37, and the fixing device 37 fixes the toner image of each color on the recording paper as a color image by pressurizing or heating, and then outside the machine. Discharge to the output tray.

The electric charge and toner remaining on the surface of each photoconductor drum 33 after the primary transfer are removed by a static eliminator, a cleaner unit, or the like around each photoconductor drum 33.

A switchback device 38, which is a recording paper reversing device, is arranged below the fixing device 37. This is for reversing the recording paper having the image fixed on one side in the case of performing double-sided printing and re-entering the secondary transfer device 36.

In the above description, the recording body on which the image forming unit 30 forms an image is described as a recording paper which is a paper medium, but the present invention is not limited to this. In addition to the recording paper, other media such as a recording film may be used.

Subsequently, the configuration of the control unit that controls the image forming apparatus 1 will be described.
FIG. 3 is a diagram showing an example of the hardware configuration of the control unit 100. Here, as the configuration of the control unit 100, the configuration of the image reading unit 10 related to the foreign matter determination process described later is mainly shown.

The main body control board 102 includes a microcomputer and comprehensively controls an image reading unit 10 (see FIG. 1), a recording paper supply unit 20 (see FIG. 1), an image forming unit 30 (see FIG. 1), and the like. .. Specifically, the main body control board 102 includes a microcomputer, an input / output interface circuit of the operation panel 101, a communication interface circuit (including "transmitting means" and "receiving means"), and the like. The input / output interface circuit and the communication interface circuit of the operation panel 101 are connected to the microcomputer via a bus.

The microcomputer has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the CPU loads a control program of the ROM into the RAM and executes it. By executing the control program, the microcomputer controls the image reading unit 10, the recording paper supply unit 20, the image forming unit 30, and the like by communicating with each controller via a communication interface circuit. Further, the microprocessor communicates with the operation panel 101 via the input / output interface circuit, detects a user operation (operation of the reading start key, etc.) on the operation panel 101, and displays display information on the operation panel 101 (“notification”). (Including display of notification information as "means").

The reading controller 103 is provided in the ADF 10b, and is configured in an ASIC (Application Specific Integrated Circuit) or the like. As an external interface (I / F), the reading controller 103 includes a communication I / F 200 that communicates with the main body control board 102, an input I / F that inputs outputs from various detection sensors of the image reading unit 10, and an image reading unit. Output I / F that outputs control signals to 10 various drive motors, and input / output I / O that outputs timing signals to the second fixed reading unit 16 and inputs output data from the second fixed reading unit 16. It has / F and so on. The other first fixed reading unit 15 (see FIG. 2) is provided in the scanner 10a and is communicably connected to the main body control board 102.

The reading controller 103 is activated by receiving power supplied from the main body control board 102 or the like, and performs a reading operation in a predetermined procedure. For example, the reading controller 103 reads in the following procedure while monitoring the output from the detection sensor, controlling the motor, controlling the second fixed reading unit 16, and communicating with the main body control board 102. Do the action. Here, only the main procedure of the reading operation including the communication with the main body control board 102 will be shown.

When the scanning controller 103 reads the detection signal of the document bundle MS from the document setting sensor 61, the scanning document setting operation is completed. Then, when the scanning controller 103 receives the scanning start signal indicating the operation of the scanning start key by the user from the main body control board 102, the scanning controller 103 separates and conveys the documents one by one from the document bundle MS. When the document reaches the resist stop position by a predetermined transport operation, the reading controller 102 stops the document at the resist stop position and transmits a resist stop signal to the main body control board 102. Then, upon receiving the operation start signal from the main body control board 102, the reading controller 103 starts conveying the document at a predetermined speed, and controls the first fixed reading unit 15 and the second fixed reading unit 16. Performs a predetermined reading operation.

The reading controller 103 includes a digital image processing circuit 300. The digital image processing circuit 300 performs black correction, white correction, and the like of the read data (image data) output from the second fixed reading unit 16, converts the corrected image data into a format, and outputs the corrected image data to the main body control board 102. To do.

Further, after the digital image processing circuit 300 is started, the second fixed reading unit 16 is made to read the density reference member 54 at a predetermined timing when there is no document at the second reading position 53 (see FIG. 2), and the reading thereof is performed. Foreign matter determination processing is performed based on the shading data generated from the data. The “foreign matter determination process” is a process for detecting foreign matter such as dirt adhering to a member on the optical path of light imaged on the image sensor of the second fixed reading unit 16. The member on the optical path is, for example, the contact glass of the second fixed reading unit 16 for bringing the original into close contact, the concentration reference member 54 (see FIG. 2), and the like.

(Foreign matter judgment)
FIG. 4 is a diagram showing an example of the arrangement relationship between the second fixed reading unit 16 (see FIG. 2) and the concentration reference member 54 (see FIG. 2). As shown in FIG. 4, the second fixed reading unit 16 includes an image sensor 161, a rod lens array 162, and the like. In addition, although not shown, it also has contact glass, a lighting device, and the like.

The image sensor 161 is a CMOS (Complementary MOS) image sensor or the like. The image sensor 161 has photoelectric conversion elements spread in the main scanning direction. Here, in order to facilitate the explanation, it is assumed that the photoelectric conversion elements are laid out in a row in the main scanning direction, but R (Red) G (Green) B (Blue) color filters are provided and each of them is provided. It may be arranged in a plurality of rows according to the color.

The rod lens array 162 is an example of a “lens”, in which a plurality of rod lenses are arranged in a row in the main scanning direction.

The document X is conveyed with the first surface side of the document X along the density reference member 54, and the second surface side of the document X is illuminated by the lighting device. When there is no document X, the density reference member 54 is illuminated.

Due to the illumination of the illumination device, the reflected light from the density reference member 54, the document X conveyed to the second reading position 53, and the like is incident on the rod lens array 162 and imaged on the image sensor 161.

The density reference member 54 functions as a reference white portion for correcting the data read by the image sensor 161. Further, the density reference member 54 also has a function of suppressing the floating of the document at the second reading position 53 here.

FIG. 5 is a diagram showing an example of the configuration of the control block of the second fixed reading unit 16. As shown in FIG. 5, the second fixed reading unit 16 has a light source unit 201 as a lighting device, and has a pixel circuit 202, an amplifier 203, and an A / D (Analog-to-Digital) as an image sensor 161. It has a conversion circuit 204.

The light source unit 201 has a light source such as an LED (Light Emitting Diode), a fluorescent lamp, and a cold cathode tube, and drives the light source. The pixel circuit 202 has a photoelectric conversion element, and photoelectrically converts the light imaged on the photoelectric conversion element to output an electric signal (analog pixel signal). The amplifier 203 amplifies the pixel signal output from each pixel circuit 202. The A / D conversion circuit 204 converts the amplified signal into a digital signal.

As shown in FIG. 5, the reading controller 103 to the second fixed reading unit 16 receive an on / off signal d1 for driving the lighting device and a drive timing signal d2 for driving the pixel circuit 202 via the output I / FC10. Etc. are entered. In addition, a power source for driving is also supplied from the reading controller 103 to the second fixed reading unit 16. From the second fixed reading unit 16 to the reading controller 103, the data string D1 output from the A / D conversion circuit 204, that is, the reading data of the density reference member 54 (later shading data) and the reading data of the document X (later). Image data) is input via the input I / FC11.

FIG. 6 is a diagram showing an example of a block configuration of the digital image processing circuit 300. The digital image processing circuit 300 is a circuit that digitally processes the read data input from the second fixed reading unit 16. The digital image processing circuit 300 includes a black correction processing block 301, a white correction processing block 302, an image processing block 303, a frame memory 304 for storing image data output by the image processing block 303, and image data of the frame memory 304. Has an output control circuit 305 for converting the format to the main body control board 102. Further, the digital image processing circuit 300 has a foreign matter determination processing block 400.

The black correction processing block 301 has an offset memory, and stores data (offset data) indicating a black level offset component in the offset memory. The offset data is the data string D1 (in this case, black level data for each pixel) input from the second fixed reading unit 16 (see FIG. 5) with the light source unit 201 (see FIG. 5) turned off. is there.

The white correction processing block 302 has a shading data memory, and white-corrects the read data (that is, image data) of the original X by the shading data. The procedure for generating shading data in the shading data memory will be described later.

The image processing block 303 performs image processing on the image data of the original X after white correction. Specifically, when the data string D1 (image data of the original X) is input from the second fixed reading unit 16 with the light source unit 201 lit, the white correction processing block 302 first white-corrects the input image. The image processing block 303 performs image processing such as interline correction on the image after white correction, and stores the processed image in the frame memory 304.

The foreign matter determination processing block 400 performs the foreign matter determination processing based on the shading data. When the foreign matter determination processing block 400 determines that there is no foreign matter, it notifies the communication I / F 200 or the like to that effect.

FIG. 7 is a diagram showing an example of a control procedure when the digital image processing circuit 300 generates shading data. First, the white correction processing block 302 acquires offset data from the offset memory of the black correction processing block 301 (S1).

Subsequently, the digital image processing circuit 300 lights the light source unit 201 (S2), and the white correction processing block 302 inputs the data string D1 (read data of the density reference member 54) from the second fixed reading unit 16 (S3). ).

Then, the white correction processing block 302 generates shading data from the read data of the density reference member 54 and stores it in the shading data memory (S4). Specifically, the white correction processing block 302 generates shading data by subtracting the offset data from the read data of the density reference member 54.

By subtracting the offset data, the shading data is obtained by removing the offset component individually possessed by each photoelectric conversion element.

In the present embodiment, the white correction processing block 302 of the digital image processing circuit 300 mainly corresponds to the "data processing means". Further, the foreign matter determination processing block 400 mainly corresponds to the "extraction means" and the "output means". Hereinafter, an example of the foreign matter determination processing block 400 will be described.

(Example 1)
FIG. 8 is a diagram showing an example of the configuration of the detailed block of the foreign matter determination processing block 400 of the first embodiment. The foreign matter determination processing block 400 shown in FIG. 8 has a smoothing unit 401 as an example of the “smoothing means” and a determination unit 402 as an example of the “first determination means”.

The smoothing unit 401 is a processing unit that performs a process of smoothing the output data (shading data) of the shading data memory 3000. The determination unit 402 is a processing unit that performs a process of determining whether or not a foreign substance is contained. Each process of the smoothing unit 401 and the determination unit 402 will be specifically described with reference to FIGS. 9 to 11.

FIG. 9 is an explanatory diagram of the foreign matter determination process. The black dots shown in each figure of FIG. 9 represent the output levels of each pixel in an arrangement in the main scanning direction.

FIG. 9A is an example of an output pattern showing the output level of each pixel of the output data (that is, “shading data”) of the shading data memory 3000. FIG. 9A shows, as an example, a state in which the black spot P1 indicating the presence of a foreign matter suddenly drops and the foreign matter signal is buried between the maximum amplitude and the minimum amplitude in the vicinity.

The smoothing unit 401 smoothes the value (output value) taken by each black dot in FIG. 9A by moving average in units of the number of pixels corresponding to the pitch interval of the rod lens. For example, the pitch interval of the rod lenses is 0.3 mm, and the resolution in the main scanning direction is 600 dpi. In this case, since the number of pixels corresponding to the pitch interval of the rod lens is about 7.09, the moving average is performed by setting the parameter "m" of the number of moving average pixels to "m = 7".

FIG. 10 is an explanatory diagram of the smoothing unit 401 for the smoothing process accompanied by the moving average. The smoothing unit 401 sets each pixel value (output value) of the shading data output from the shading data memory 3000 in the main scanning direction order to the pixel numbers 0 to pixel numbers n of the input unit M1 of the smoothing unit 401 in this order. input. Further, the smoothing unit 401 defines the parameter α = (m-1) / 2 (rounded down to the nearest whole number), calculates the average based on the number of moving average pixels (m = 7), and shifts the pixel numbers to average each of them. The result is output to the pixel number of the output unit M2 that satisfies the relationship of the following equation (1).

"Pixel number of output unit M2" = "Pixel number of averaging end of input unit M1" -α ... (1)

For example, since α = 3 at m = 7 as in this example, “the averaging end pixel number of the input unit M1” = “6” for the pixel numbers 0 to 6 of the input unit M1. Therefore, from the equation (1), the "pixel number of the output unit M2" is "3", and the output destination of the average result is the pixel number 3 of the output unit M2. Similarly, for the pixel numbers 1 to 7 of the input unit M1 in which the pixel numbers are shifted by one, "the averaging end pixel number of the input unit M1" = "7". Therefore, from the equation (1), the “pixel number of the output unit M2” is “4”, and the output destination of the average result is the pixel number 4 of the output unit M2.

When the pixel numbers are shifted one by one in this way, finally, from the pixel numbers n-6 of the input unit M1 to the pixel number n, "the averaging end pixel number of the input unit M1" = "n". From the equation (1), the "pixel number of the output unit M2" is "n-3", and the output destination of the average result is the pixel number n-3 of the output unit M2.

This moving average also removes random noise contained in the shading data.

FIG. 9B shows the result when the value (output value) taken by the black spot in FIG. 9A is smoothed by the moving average by the smoothing unit 401, and corresponds to the data string of the moving average result in the main scanning direction. Then, this is output from the output unit M2.

As shown in FIG. 9B, the average values of the seven pixels not including the discontinuity of the black point P1 in FIG. 9A show substantially the same value and become substantially constant (output Q1). On the other hand, the average value of each of the seven pixels including the discontinuity of the black point P1, and in this example, each of the seven consecutive moving average results, has a discontinuity, so the value drops by approximately the same width and is substantially constant ( Output Q2). That is, the black spot P1 (foreign matter signal) buried between the maximum amplitude and the minimum amplitude in the vicinity can be separated from the output Q1 of the pixel without foreign matter as a result of the moving average and can be extracted. The determination unit 402 determines the foreign matter by calculating the amount of change in the front and rear pixels from the moving average result (data of the moving average result in the main scanning direction of the output unit M2) output from the smoothing unit 401.

FIG. 11 is a diagram showing a correspondence relationship between the pixel number of the moving average result (moving average data) output by the smoothing unit 401 and the pixel number of the determination unit 402 outputting the amount of change in the front and rear pixels of the moving average data. is there. The determination unit 402 outputs the moving average result output from the smoothing unit 401 to the output unit M3 by taking the difference between the front and rear pixels in the main scanning direction. The pixel number of the output destination of the difference data is subject to the following condition (2).

"Pixel number of output unit M3" = "Pixel number" on the rear side of the previous and next pixel numbers ... (2)

For example, the determination unit 402 takes the difference between the moving average results of the pixel number 3 (rear side) and the pixel number 4 (front side) as the front and rear pixel numbers, and the difference result (difference data) is a condition (2). ), The data is output to the pixel number 3 of the output unit M3. Similarly, the determination unit 402 takes the difference between the moving average results of the pixel number 4 (rear side) and the pixel number 5 (front side), and sets the difference result (difference data) as the output unit from the condition (2). Output to pixel number 4 of M3.

In this way, the differences are sequentially taken along the main scanning direction, and finally, the determination unit 402 determines the difference between the moving average results of the pixel numbers n-4 (rear side) and the pixel numbers n-3 (front side). And output the difference result (difference data) to the pixel number n-4 of the output unit M3.

FIG. 9C shows the result when the moving average result shown by the black dot in FIG. 9B is subjected to the difference processing by the determination unit 402, that is, the data of the output unit M3. As shown in FIG. 9C, in each of the output Q1 and the output Q2 of FIG. 9B, the difference between the front and rear pixels is substantially 0, so that the output is approximately 0. On the other hand, at the boundary including the output Q1 and the output Q2 in the front and rear pixels, the difference = output Q1-output Q2 (difference> 0) or the difference = output Q2-output Q1 (difference <0), and the output is a positive value or a negative value. Takes the value of.

The determination unit 402 sets the upper limit value H1 and the lower limit value L1 in advance, determines that the difference is within the range of the upper limit value H1 and the lower limit value L1 from the difference of the output unit M3, determines that it is a normal range, and determines the upper limit value H1. If it deviates from the range of the lower limit value L1, it is determined to be a foreign substance. It should be noted that, in advance, stains exceeding a predetermined size, stains exceeding a predetermined density, etc. are regarded as foreign substances, and other normal ranges are determined in advance, and the upper limit value H1 and the lower limit value L1 are set as threshold values. To do.

As shown in FIG. 9C, when there is a foreign substance, the normal range is exceeded and it can be determined that the foreign substance is a foreign substance. In FIG. 9C, foreign matter is detected at two places, but the actual foreign matter is at one of them near the main scanning direction.

When the determination unit 402 determines that the foreign matter is determined, the determination unit 402 notifies the main body control board 102 of the discovery of the foreign matter via the communication I / F 200 of the reading controller 103.

(Example 2)
Next, the second embodiment of the foreign matter determination process will be described. When the rod lens array 162 is used, the incident light passing through each rod lens has a difference in intensity depending on each position on the image sensor 161. This difference is represented by a displacement that changes over a long period in the main scanning direction. The displacement is layered as a low frequency component in the read data output from the image sensor 161. Therefore, in the second embodiment, a foreign matter determination process for detecting a foreign matter buried in the swing width of the entire main scanning direction including the low frequency component of the read data output from the image sensor 161 will be described.

FIG. 12 is an explanatory diagram of the foreign matter determination process of the second embodiment. In FIG. 12, black dots indicating the output level of each pixel are omitted.

FIG. 12A is an example of an output pattern of shading data having the low frequency component (this is referred to as an “original output pattern”). The pattern R1 shown by the solid line is the original output pattern. The pattern R2 shown by the broken line is a low frequency component included in the pattern R1.

The distance between the peaks of the pattern R1 corresponds to the pitch of the rod lens. The output decreases as the distance from the position of the optical axis (mountain position) of the rod lens within one pitch increases.

FIG. 12A shows an output value T1 as a signal indicating a foreign substance. Since the output value T1 is out of the vibration range of the pattern R1 (the vibration range of the vibration centered on the pattern R2), it should be detected as a foreign substance. However, due to the influence of the pattern R2, the swing width as a whole in the main scanning direction is widened, and the output value T1 is buried within the swing width, so that the output value T1 cannot be detected. Specifically, the interval between the maximum value of the amplitude and the minimum value of the amplitude common to the entire pattern R1 is widened by the pattern R2, and as a result, the swing width of the entire main scanning direction indicated by the maximum value and the minimum value is widened. The output value T1 indicating an abnormality is buried inside.

Therefore, in the second embodiment, as shown in FIG. 12B, the low frequency component (pattern R2) included in the original output pattern (pattern R1) is detected, and as shown in FIG. 12C, the original output pattern is detected. The low frequency component (pattern R2) is removed from (pattern R1), and the output value T1 can be detected from the high frequency component (pattern R3) after removal. In the second embodiment, the foreign matter determination processing block 400 is configured as follows.

FIG. 13 is a diagram showing an example of the configuration of the detailed block of the second embodiment of the foreign matter determination processing block 400. The foreign matter determination processing block 400 shown in FIG. 13 includes a smoothing unit 401, an example calculation unit 500 of the “low frequency component removing means”, an amplitude estimation unit 501 of an example of the “threshold determination means”, and a “second second”. It has a determination unit 502, which is an example of the "determination means". The arrow shown in FIG. 13 indicates the flow of data to be processed. The same processing blocks as those in the first embodiment are designated by the same reference numerals. Hereinafter, the processing of the detailed block of the second embodiment and the flow of the processing will be specifically described.

FIG. 14 is a diagram showing an example of the processing flow of the detailed block of the second embodiment. As shown in FIG. 14, first, the smoothing unit 401 performs a process of smoothing the original output pattern data output from the shading data memory 3000 (S11).

Specifically, the smoothing unit 401 moves and averages the original output pattern data to generate a low frequency from the original output pattern (see pattern R1 in FIG. 12A) by smoothing the original output pattern. The component output pattern (see pattern R2 in FIG. 12B) is detected. Since the moving average processing will be described repeatedly in the first embodiment, the description thereof will be omitted.

Subsequently, the calculation unit 500 outputs the original output pattern data (data of the pattern R1) output from the shading data memory and the output pattern data after smoothing (data of the pattern R2) output from the smoothing unit 401. Data (high frequency component output pattern data) of the output pattern (see pattern R3 in FIG. 12C) obtained by removing the output pattern of the low frequency component from the original output pattern by input and calculation is extracted (S12).

For example, the calculation unit 500 extracts the high frequency component output pattern data by subtracting (or dividing) the output value of the corresponding pixel number of the low frequency component output pattern data from the output value of each pixel number of the original output pattern data. To do. If there is no corresponding pixel number, it shall be excluded from the judgment target in the subsequent stage.

Subsequently, the amplitude estimation unit 501 inputs the high frequency component output pattern data from the calculation unit 500, calculates the maximum value and the minimum value of the amplitude of the high frequency component output pattern, and determines the normal range (S13). Further, the amplitude estimation unit 501 sets the threshold value in the normal range in the determination unit 502 (S14).

Since the threshold value in the normal range is obtained in this process, it should be performed in a state where there is no foreign matter on the parts on the optical axis such as the concentration reference member 54, such as when manufacturing a product or when replacing a part to be read such as the concentration reference member 54. Is desirable. Therefore, this process is selectively executed when, for example, an instruction is received by the operation panel 101 and an instruction is given from the main body control board 102 at the time of manufacturing a product or replacing a part of the concentration reference member 54. Alternatively, the reading controller 103 may be provided with a changeover switch such as a DIP switch, and the process may be executed by manually switching the changeover switch.

After the selective execution of steps S13 and S14, the determination unit 502 compares each value of the high frequency component output pattern data input from the calculation unit 500 with the set threshold value, and the foreign matter in the high frequency component output pattern. (S15).

Here, the processing of the amplitude estimation unit 501 and the determination unit 502 in steps S13 to S15 will be described in more detail. Since the amplitude of the high-frequency component changes depending on the assembly variation and the individual variation of the parts, a method of calculating the amplitude for each individual will be described here.

15 and 16 are explanatory views of a method of calculating the maximum value and the minimum value by the amplitude estimation unit 501 (step S13 of FIG. 14). The amplitude estimation unit 501 sequentially extracts the maximum value and the minimum value in the order of pixel numbers from the output data of the calculation unit 500 (that is, high frequency component output pattern data) in units of the number of corresponding pixels of the rod lens (number of pixels m = 7). And calculate the average value of the maximum value and the average value of the minimum value.

Specifically, as shown in FIG. 15, the amplitude estimation unit 501 is based on the first pixel number (pixel number 3 as an example) of the high-frequency component output pattern data, and from this reference pixel to the number of corresponding pixels of the rod lens. (In this example, the number of corresponding pixels including the reference pixel is set to "7") is set in the range, that is, the pixel numbers 3 to 9 are set in the range, and the maximum value max and the minimum value min are extracted.

Subsequently, the amplitude estimation unit 501 uses the next pixel number 4 as a reference, and ranges from the reference pixel number to the number of corresponding pixels of the rod lens, that is, the pixel numbers 4 to 10 in the range. The maximum value max and the minimum value min are extracted.

The amplitude estimation unit 501 performs the extraction process of the maximum value max and the minimum value min by increasing the pixel number as the reference pixel by 1, and the last pixel corresponding to the number of corresponding pixels becomes the final pixel n-3. Repeat until.

FIG. 16 is a diagram showing an example of the correspondence between the pixel number of the input unit M4 of the high frequency component output pattern data of the amplitude estimation unit 501 and the pixel number of the holding unit M5 of the maximum value max and the minimum value min.

The amplitude estimation unit 501 outputs the maximum value max and the minimum value min to the holding unit M5 so as to satisfy the following condition (3).

"Pixel number" = "reference pixel number" + m-1-α ... (3)
However, the "reference pixel number" is limited to the pixel number n- (m-1).

The example shown in FIG. 16 is for the case of m = 7 and α = 3. For example, the amplitude estimation unit 501 holds the maximum value max and the minimum value min in the range of pixel numbers 3 to 9 with the pixel number 3 of the input unit M4 as a reference pixel according to the condition (3). Output to pixel number 6 of. Further, the maximum value max and the minimum value min in the range from the pixel number 4 to the pixel number 10 with the pixel number 4 of the input unit M4 as the reference pixel are output to the pixel number 7 of the holding unit M5 according to the condition (3). To do. In this way, the amplitude estimation unit 501 outputs the maximum value max and the minimum value min in the range from the reference pixel to the pixel number one larger than the holding unit M5 while increasing the pixel number of the reference pixel by one. Is repeated until the pixel number n-6 of the holding unit M5 is filled.

The amplitude estimation unit 501 determines a threshold value indicating a normal range based on the maximum value max and the minimum value min held in each pixel number of the holding unit M5. Specifically, the amplitude estimation unit 501 calculates the average value of the maximum value max of each pixel number, adds a predetermined positive value (margin) to the calculated average value, and sets the upper limit of the normal range as the addition result. The threshold value (upper limit value H1 (see FIG. 17)) is determined. Further, the amplitude estimation unit 501 calculates the average value of each minimum value min of each pixel number, and subtracts a predetermined positive value (margin) from the calculated average value to subtract a predetermined positive value (margin) from the subtraction result, which is a threshold value indicating the lower limit of the normal range. (Lower limit value L1 (see FIG. 17)) is determined.

However, the upper limit margin is set so that the upper limit value H1 takes a value larger than the maximum value max of each pixel number, and the lower limit margin is set so that the lower limit value L1 is larger than the respective minimum value min of each pixel number. Is set to take a small value.

FIG. 17 is an explanatory diagram of the determination process of the determination unit 502. As shown in FIG. 17, the determination unit 502 sets the output value T1 (signal indicating a foreign substance) appearing in the high frequency component (pattern R3) after removing the low frequency component (pattern R2) to a threshold value (upper limit value H1) indicating a normal range. And the lower limit value L1).

In this example, the output value T1 appears on the lower limit side, and the value is lower than the lower limit value L1. Therefore, the determination unit 502 determines that the output value T1 is a foreign substance by the determination based on the lower limit value L1.

(Example 3)
Next, the third embodiment of the foreign matter determination process will be described. If the rod lens array 162 is arranged in a bent state when the close contact type image sensor is assembled, the amplitude of the shading data output pattern is attenuated in the main scanning direction and is not constant. In the third embodiment, on the premise of the second embodiment, the shading data is further divided into N blocks in the main scanning direction, and a threshold value in the normal range is set for each block.

FIG. 18 is a diagram showing an example of a state in which the rod lens is displaced from the sensor when the rod lens is arranged in the image sensor in a bent state. In FIG. 18, assuming that the rod lens array 162 is arranged in a state of being bent in a horizontal plane with respect to the image sensor 161 from above the rod lens array 162 (above the rod lens array 162 in FIG. 4). An example of the state of deviation between the rod lens array 162 and the image sensor 161 when viewed is shown.

The center line J2 of the rod lens array 162 shown in FIG. 18 is a line indicating the arrangement of each rod lens, and the center line J1 of the image sensor 161 is a center line in the longitudinal direction of the image sensor 161. As shown in FIG. 18, when the center line J2 of the rod lens array 162 deviates from the center line J1 of the image sensor 161, it is from the center line J2 as compared with the photoelectric conversion element in the range on the center line J2 of the rod lens array 162. The light intensity of the photoelectric conversion element in the warped range decreases, and the output decreases.

FIG. 19 is a diagram showing an example of a high frequency component output pattern of data obtained by removing low frequency components from the shading data generated in the arrangement configuration shown in FIG. As shown in FIG. 19, the amplitude of the high frequency component output pattern P3 is attenuated in the main scanning direction.

When the amplitude is not constant in this way, the gap with the threshold value (upper limit value H1, lower limit value L1) in the normal range becomes large at the position where the amplitude is small, and when foreign matter is contained here, it becomes difficult to detect it. Become. Therefore, when the amplitude is not constant due to attenuation (or amplification) in this way, the high frequency component output pattern P3 is divided into N blocks, and a threshold value in the normal range is set for each block.

FIG. 20 is a diagram conceptually showing division into N blocks and setting of a threshold value for each block performed by the amplitude estimation unit 501 as a “division means”. The amplitude estimation unit 501 divides the high-frequency component output pattern P3 into N blocks as shown in FIG. 20 (a), and each divided block has a threshold value (upper limit value, lower limit value) = as shown in FIG. 20 (b). (H1, L1), (H2, L2) ..., (HN, LN) are determined. The number of divisions and the number of pixels included in each block may be set as appropriate.

For example, if the attenuation in the main scanning direction is steep, the number of divisions is increased to reduce the number of pixels in the block, and if the attenuation is gradual, the number of divisions is decreased to increase the number of pixels in the block. Further, if the image sensor 161 is configured by combining a plurality of sensor chips, one block may be assigned to each sensor chip. However, when N = 1, it corresponds to the second embodiment.

Specifically, the amplitude estimation unit 501 divides the holding unit M5 into N blocks (N is a positive integer indicating the number of divisions), and from the maximum value max and the minimum value min stored in each pixel number in the block. The threshold value indicating the normal range is determined for each block. Then, the amplitude estimation unit 501 sets the block information indicating the range of the pixel number and the threshold value determined for the block in the determination unit 502.

The determination unit 502 determines the foreign matter for each pixel of the high-frequency component output pattern data by using the threshold value of the block to which the pixel belongs.

(Example 4)
Due to the internal circuit configuration of the sensor chip such as the close contact type image sensor, a predetermined photoelectric conversion element in the sensor chip may exhibit characteristics different from those of other photoelectric conversion elements.

FIG. 21A is a diagram showing an example of an output pattern when several pixels at the end of the sensor chip show extremely low output as compared with other pixels. As shown in FIG. 21A, the output value of several pixels Y1 at the end of the sensor chip is extremely lower than that of the other pixels, and the output exceeds the threshold value. In this case, even if there is no foreign matter, it may be erroneously detected as having a foreign matter.

FIG. 21B is a diagram showing a mask region set as a “mask setting means” so as not to perform foreign matter determination in a range showing its specific characteristics. As shown in FIG. 21B, a mask region Y2 indicating that the foreign matter is not a determination target is set in the few pixels Y1 showing the specific characteristics of FIG. 21.

Specifically, in the determination unit 502, mask information is set in advance for the pixel number indicating a specific characteristic among the pixel numbers to be determined in the high frequency component output pattern data input from the calculation unit 500.

As a result, the determination unit 502 does not determine the foreign matter for the pixel set as the mask information in the high frequency component output pattern data, but determines the foreign matter for the other pixels.

In this way, if the mask area is set in advance in a range showing specific output characteristics, false detection as a foreign substance can be avoided. Further, even when the total length of the reading sensor is longer than the total length of the density reference member 54, if the region without the density reference member 54 is set as the mask region, foreign matter can be foreign matter even for shading data outside the range of the density reference member 54. There will be no false positives.

(Example 5)
A combination of the configurations of the first embodiment and the second embodiment as the foreign matter determination processing block 400 is shown.

FIG. 22 is a diagram showing an example of the configuration of the detailed block of the fifth embodiment of the foreign matter determination processing block 400. The foreign matter determination processing block 400 shown in FIG. 22 includes a smoothing unit 401, a determination unit (first determination unit) 402, a calculation unit 500, an amplitude estimation unit 501, and a determination unit (second determination unit) 502. And have. The arrow shown in FIG. 22 indicates the flow of data to be processed. The same processing blocks as those in the first and second embodiments are designated by the same reference numerals.

In the configuration of the fifth embodiment, the foreign matter can be determined by the two foreign matter determination processes of the first embodiment and the second embodiment. Specifically, the smoothing unit 401 and the determination unit (first determination unit) 402 determine the foreign matter of the first embodiment. Further, the smoothing unit 401, the calculation unit 500, the amplitude estimation unit 501, and the determination unit (second determination unit) 502 perform the foreign matter determination of the second embodiment.

With this configuration, it becomes possible to detect foreign matter signals inside and outside the high frequency component, which are buried in the shading data including the low frequency component.

(Example 6)
When the foreign matter determination processing block 400 determines a foreign matter, the processing in which the foreign matter determination processing block 400 notifies the user of the removal of the foreign matter will be described as information indicating that there is a foreign matter.

When the foreign matter determination processing block 400 detects a foreign matter, the foreign matter determination processing block 400 notifies the main body control board 102 of a signal indicating the detection of the foreign matter via the communication I / F 200. When the main body control board 102 receives the signal indicating the detection of the foreign matter, the main body control board 102 transmits the notification screen information prompting the user to remove the foreign matter to the operation panel 101. The notification screen information includes display information such as "Please clean the concentration reference member, contact glass, etc."

Although it has been described here that the main body control board 102 transmits the notification screen information to the operation panel 101 when a signal indicating the detection of a foreign substance is received, the main body control board 102 transmits the information indicating that there is a foreign substance. The signal is not limited to this. For example, it may be a signal for designating a notification sound for prompting cleaning, a signal for designating lighting of a lamp, or the like.

As described above, in the present embodiment, it is possible to detect the foreign matter signal buried in the entire swing width from the output level from each pixel circuit, and the foreign matter detection accuracy is improved.

In the present embodiment, an example is shown in which the image reading device is applied to the image forming device and the scanned image of the image reading device is used for image forming. However, the scanned image generated by using the image reading device alone is shown. May be output as a file to a hard disk or recording medium.

Further, in the present embodiment, the image reading device has a built-in reading controller 103, but a part or all of the reading controller 103 is supplied and supplied in the form of an image processing device (for example, an IC chip). The image processing device may be mounted on a corresponding image reading device to perform foreign matter determination. The image processing device includes at least the foreign matter determination processing block 400.

300 Digital image processing circuit 301 Black correction processing block 302 White correction processing block 303 Image processing block 304 Frame memory 305 Output control circuit 400 Foreign matter judgment processing block

Japanese Patent No. 4737044

Claims (11)

Concentration reference member and
A light source that irradiates the concentration reference member with light,
A lens that forms the light from the density reference member and
A plurality of pixel circuits that convert the light imaged by the lens into an electric signal, and
A data processing means that generates shading data from the output value of each pixel circuit,
An extraction means for extracting foreign matter from the shading data,
An output means for outputting information indicating that there is a foreign substance on condition that the foreign substance has been extracted, and
Have,
The extraction means
From the data string of the moving average result obtained by the moving average from the shading data, a foreign substance whose difference of the moving average result is out of the normal range is extracted.
Further, from the data string showing the high frequency component after removing the low frequency component from the shading data, foreign matter outside the normal range determined by the maximum value and the minimum value of the amplitude of the high frequency component is extracted.
Image reader. The lens is a rod lens array.
The extraction means
From the shading data, a data string of the moving average result is obtained by a moving average in units of the number of pixels corresponding to the pitch interval of the rod lens of the lens.
The image reading device according to claim 1. The lens is a rod lens array.
The extraction means has a maximum value and a minimum amplitude of the high frequency component in a data string showing the high frequency component after removal of the low frequency component, in units of the number of pixels corresponding to the pitch interval of the rod lenses of the rod lens array. Each value is extracted to determine the normal range determined by the maximum value and the minimum value.
The image reading device according to claim 1 or 2. The extraction means removes the low frequency component from the shading data by subtraction or division.
The image reading device according to any one of claims 1 to 3. The extraction means determines the upper limit value of the normal range from the average value of the maximum values extracted in units of the number of pixels corresponding to the pitch interval of the rod lens, and extracts the number of pixels corresponding to the pitch interval in units. The lower limit of the normal range is determined from the average value of the minimum values.
The image reading device according to claim 3. The extraction means
The data string showing the high frequency component after the removal of the low frequency component is divided into N blocks, and the normal range determined by the maximum value and the minimum value is determined for each block of the N block.
The image reading device according to claim 1 or 2. The extraction means further includes a setting means for setting a mask in a range showing specific characteristics.
The image reading device according to any one of claims 1 to 6. The image reading device according to any one of claims 1 to 7.
An image forming means for forming an image read by the image reading device on a recording medium, and
An image forming apparatus having. In addition
A receiving means for receiving information output from the output means of the image reading device, and
A notification means for notifying that there is a foreign substance based on the information received by the reception means, and
The image forming apparatus according to claim 8. Concentration reference member and
A light source that irradiates the concentration reference member with light,
A lens that forms the light from the density reference member and
A plurality of pixel circuits that convert the light imaged by the lens into an electric signal, and
An image processing device that can be mounted on an image reader having the above.
A data processing means that generates shading data from the output value of each pixel circuit,
An extraction means for extracting foreign matter from the shading data,
An output means for outputting information indicating that there is a foreign substance on condition that the foreign substance has been extracted, and
Have,
The extraction means
From the data string of the moving average result obtained by the moving average from the shading data, a foreign substance whose difference of the moving average result is out of the normal range is extracted.
Further, from the data string showing the high frequency component after removing the low frequency component from the shading data, foreign matter outside the normal range determined by the maximum value and the minimum value of the amplitude of the high frequency component is extracted.
Image processing device. Concentration reference member and
A light source that irradiates the concentration reference member with light,
A lens that forms the light from the density reference member and
A plurality of pixel circuits that convert the light imaged by the lens into an electric signal, and
It is an image processing method of an image reader having the above.
Steps to generate shading data from the output value of each pixel circuit,
The step of extracting foreign matter from the shading data and
A step of outputting information indicating that there is a foreign substance on condition that the foreign substance has been extracted, and
Including
In the step of extracting the foreign matter,
From the data string of the moving average result obtained by the moving average from the shading data, a step of extracting a foreign substance whose difference of the moving average result is out of the normal range, and
Further, a step of extracting foreign matter outside the normal range determined by the maximum value and the minimum value of the amplitude of the high frequency component from the data string showing the high frequency component after removing the low frequency component from the shading data.
Image processing method including.

Images