JP6357906B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and an image forming apparatus.

  In an image forming apparatus, an image reading function for reading an image after formation may be provided, and feedback may be provided for color conversion processing control during image formation.

  Japanese Patent Application Laid-Open No. 2004-151858 describes that the amount of change in shading data acquired with different light amounts is obtained by using dimming control to detect white dust and black dust on the white reference plane.

  Patent Document 2 describes that white dust and black dust on the white reference and the window glass are detected from the read signals of the white reference surface and the black reference surface.

  Japanese Patent Application Laid-Open No. 2004-228561 describes that in a read signal of a white reference surface, the difference between adjacent pixels is compared with two types of threshold values, and the presence or absence of dust and an attached optical component are specified.

  Japanese Patent Application Laid-Open No. H10-228561 describes that a defective pixel is obtained from a change amount of image data obtained with different light amounts by using dimming control to detect dirt and dust on a reading target.

  Patent Document 5 describes that the amount of change in shading data acquired with different amounts of light is obtained using dimming control, and white dust on the white reference surface is detected.

JP 2011-130232 A JP 2008-147816 A Japanese Patent Laid-Open No. 06-105143 Japanese Patent Laid-Open No. 11-220621 JP 2001-086333 A

  In the present invention, when calibrating the image reading means, in addition to the achromatic color reference surface used for correcting the brightness of the image read signal, dust adhering to the chromatic color reference surface used for correcting the color of the image read signal, An object of the present invention is to obtain an image reading apparatus and an image forming apparatus that can reliably determine the presence or absence of dust present on the optical path.

The invention according to claim 1 is a reading means using a color reference surface having an achromatic color reference surface and a chromatic color reference surface, and a first detection means for detecting the presence of dust from the read information of the achromatic color reference surface. And second detection means for detecting the presence of dust from the read information of the chromatic color reference surface, and the type of optical component to which dust has adhered according to the detection results of the first detection means and the second detection means. And third detecting means for detecting.

  According to a second aspect of the present invention, in the first aspect of the present invention, the third detection unit includes the reading information of the relatively low reflectance portion of the achromatic color reference surface and the color separation of the chromatic color reference surface. Compared with the reading information of the color component that has a complementary color relationship with the color of the chromatic color reference surface in the read information, the position of the relatively high reflectivity dust and the type of the attached optical component are detected. To do.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the third detection means includes a reading information of a relatively high reflectance portion on the achromatic color reference plane, and a chromatic color reference. Compared with the reading information of the color component that is not complementary to the color of the chromatic color reference surface in the color-separated reading information of the surface, the attachment position of the dust having a relatively low reflectance and the type of the attached optical component And detect.

  According to a fourth aspect of the present invention, in the second or third aspect of the present invention, the third detection unit is configured to detect dust at the same position in the detection results of the first detection unit and the second detection unit. Is detected, the position is detected by determining that dust is present in the optical component located on the optical path other than the color reference surface. If the dust is present at a different position, the achromatic reference surface and the chromatic color reference are detected. The position is detected by determining that dust is present on at least one of the surfaces.

Invention according to claim 5, in claim 1 the invention of any one of claims 4, if the presence of dust is detected in the third detection means, the detection of the presence of dust It further has the 1st alerting | reporting means to alert | report to a user.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects of the present invention, when the presence of dust is detected by the third detection means, the user is informed of a cleaning location, Second informing means for informing the size and the type of black dust / white dust is further provided.

Invention according to claim 7, in the invention according to any one of the claims 1 to 6, where the presence of dust is detected in the third detection means, the test to be printed for color correction It further has display means for displaying the degree of overlap between the chart and the detected dust .

According to an eighth aspect of the present invention, there is provided image formation in which the image reading device according to any one of the first to seventh aspects is applied for generating a correction coefficient for calibration at the time of image formation in the image forming unit. Device.

  According to the first aspect of the present invention, in addition to the achromatic color reference surface for correcting the density during image reading, the dust adhering to the chromatic color reference surface for correcting the color tone and the dust existing on the optical path The presence or absence of can be reliably determined.

  According to the second aspect of the present invention, it is possible to detect dust (for example, white dust) having a relatively high reflectance (including the presence / absence of adhesion and the type of optical component).

  According to the third aspect of the invention, it is possible to detect dust (for example, black dust) having a relatively low reflectance (including the presence or absence of adhesion and the type of optical component).

  According to the fourth aspect of the present invention, the type of attached optical component can be specified by the positional relationship of dust.

According to invention of Claim 5 , presence of dust can be alert | reported.

According to the sixth aspect of the invention, accurate information for removing dust can be notified.

According to the seventh aspect of the present invention, erroneous update due to dust can be prevented when updating the color correction coefficient.

According to the eighth aspect of the present invention, in addition to the achromatic color reference surface for correcting the density during image reading, the dust adhering to the chromatic color reference surface for correcting the color tone and the dust existing on the optical path The presence or absence of can be reliably determined.

1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to an exemplary embodiment. 1 is a schematic configuration diagram illustrating an example of a configuration of a built-in image sensor provided in an image forming apparatus according to an embodiment. It is a perspective view of the reference | standard roll which concerns on this Embodiment. FIG. 2 is a block diagram illustrating an example of a main configuration of an electric system in the image forming apparatus according to the present embodiment. It is a functional block specialized in dust specific control performed with the control apparatus of this Embodiment. It is a flowchart which shows the dust specific control routine which concerns on this Embodiment and is performed with a control apparatus. It is a flowchart which shows the white dust detection by a yellow reference surface and a detection reference surface (black), and a calibration execution control routine. It is a standardized data characteristic diagram when white dust adheres to the yellow reference plane. It is a standardized data characteristic view when white dust adheres to the window glass. It is a flowchart which shows the black dust detection by a yellow reference surface and a white reference surface, and a calibration process execution control routine. FIG. 11 is a chart showing the correspondence between the determination results 1 to 4 in FIG. 7 and the determination results 1 to 4 in FIG. 10 based on the analysis of the standardization data Yb and Kb and the standardization data Yr and Wr.

(Overall configuration of image forming apparatus)
As shown in FIG. 1, an image forming apparatus 10 according to the present embodiment selectively forms a full color image and a monochrome image, and is connected to a first housing 10A and a first housing 10A. A second housing 10B. An image signal processing unit 13 that performs image processing on image data supplied from an external device such as a computer is provided on the upper portion of the second housing 10B.

  On the other hand, the first special color (V), second special color (W), yellow (Y), magenta (M), cyan (C), and black (K) toners are provided on the upper portion of the first housing 10A. Toner cartridges 14V, 14W, 14Y, 14M, 14C, and 14K are provided.

  Note that examples of the first special color and the second special color include colors other than yellow, magenta, cyan, and black (including transparency). In the following description, the first special color (V), the second special color (W), yellow (Y), magenta (M), cyan (C), and black (K) are distinguished for each component. Will be described with a letter as a symbol followed by any letter of V, W, Y, M, C, or K. When the first special color (V), the second special color (W), yellow (Y), magenta (M), cyan (C), and black (K) are not distinguished, V, W, Y, M , C and K are omitted.

  Under the toner cartridges 14, six image forming units 16 V, 16 W, 16 Y, 16 M, 16 C, and 16 K (collectively referred to as “image forming units 16”) corresponding to the toners of the respective colors are placed in the toner cartridges 14. It is provided to correspond.

  Exposure devices 40V, 40W, 40Y, 40M, 40C, and 40K (collectively referred to as “exposure device 40”) provided for each image forming unit 16 are subjected to image processing by the image signal processing unit 13 described above. Image data is received from the image signal processing unit 13. Then, the light beam L modulated in accordance with the image data is irradiated to image holders 18V, 18W, 18Y, 18M, 18C, and 18K (hereinafter collectively referred to as “image holder 18”). Yes.

  In each image forming unit 16, an electrostatic latent image is formed on each image carrier 18 by irradiating each image carrier 18 with the light beam L from each exposure device 40.

  Around each image carrier 18, a corona discharge (non-contact charging) scorotron charger that charges the image carrier 18 and an electrostatic latent image formed on the image carrier 18 by the exposure device 40 are developed. A developing device that develops with toner, which is an example of an agent, a blade that removes the developer remaining on the image carrier 18 after transfer, and a static eliminator that performs static elimination by irradiating the image carrier 18 after transfer with light. Is provided. The scorotron charger, the developing device, the blade, and the static eliminator are arranged in this order from the upstream side to the downstream side in the rotation direction of the image carrier 18 so as to face the surface of the image carrier 18.

  A transfer unit 32 is provided below each image forming unit 16. The transfer unit 32 includes an annular intermediate transfer belt 34 that contacts each image carrier 18, and primary transfer rolls 36 </ b> V, 36 </ b> W, 36 </ b> Y that multiplex-transfer toner images formed on each image carrier 18 onto the intermediate transfer belt 34. 36M, 36C, 36K (collectively referred to as “primary transfer roll 36”).

  The intermediate transfer belt 34 includes a drive roll 38 that is driven by a motor (not shown), a tension applying roll 41 that applies tension to the intermediate transfer belt 34, an opposing roll 42 that faces a secondary transfer roll 62 described below, It is wound around a plurality of winding rolls 44. And it is circularly moved in one direction (counterclockwise direction in FIG. 1) by the drive roll 38.

  Each primary transfer roll 36 is disposed opposite to the image carrier 18 of each image forming unit 16 with the intermediate transfer belt 34 interposed therebetween. The primary transfer roll 36 is applied with a transfer bias voltage having a polarity opposite to the toner polarity by a power supply unit (not shown). With this configuration, the toner image formed on the image carrier 18 is transferred to the intermediate transfer belt 34.

  On the opposite side of the drive roll 38 across the intermediate transfer belt 34, there is provided a removing device 46 that removes residual toner, paper dust and the like on the intermediate transfer belt 34 by bringing the blade into contact with the intermediate transfer belt 34. .

  Below the transfer unit 32, a plurality of recording medium storage units 48 that store a recording medium P as an example of a medium such as paper are provided. Each of the recording medium accommodating portions 48 can be pulled out from the first housing 10A. A delivery roll 52 that feeds the recording medium P from each recording medium container 48 to the transport path 60 is provided above one end side (right side in front view in FIG. 1) of each recording medium container 48.

  In each recording medium accommodating portion 48, a bottom plate 50 on which the recording medium P is placed is provided. The bottom plate 50 is lowered by an instruction from a control means (not shown) when the recording medium accommodating portion 48 is pulled out from the first housing 10A. When the bottom plate 50 is lowered, a space in which the user replenishes the recording medium P is formed in the recording medium accommodating portion 48.

  When the recording medium accommodating portion 48 pulled out from the first housing 10A is attached to the first housing 10A, the bottom plate 50 is raised by an instruction from the control means. As the bottom plate 50 moves up, the uppermost recording medium P placed on the bottom plate 50 and the delivery roll 52 come into contact with each other.

  On the downstream side in the recording medium conveyance direction of the delivery roll 52 (hereinafter sometimes simply referred to as “downstream side”), a separation roll 56 that separates the recording media P delivered from the recording medium accommodating portion 48 one by one. Is provided. A plurality of transport rolls 54 that transport the recording medium P downstream in the transport direction are provided on the downstream side of the separation roll 56.

  The conveyance path 60 provided between the recording medium storage unit 48 and the transfer unit 32 folds the recording medium P sent out from the recording medium storage unit 48 to the left side as viewed from the front in FIG. Further, the second folding portion 60B extends to the transfer position T between the secondary transfer roll 62 and the opposing roll 42 so as to be folded back to the right in the front view in FIG.

  The secondary transfer roll 62 is applied with a transfer bias voltage having a polarity opposite to the toner polarity by a power feeding unit (not shown). With this configuration, each color toner image transferred onto the intermediate transfer belt 34 is secondarily transferred by the secondary transfer roll 62 onto the recording medium P conveyed along the conveyance path 60.

  A preliminary path 66 extending from the side surface of the first housing 10 </ b> A is provided so as to join the second folding portion 60 </ b> B of the transport path 60. The recording medium P sent out from another recording medium accommodation unit (not shown) arranged adjacent to the first housing 10 </ b> A can enter the conveyance path 60 through the spare path 66.

  On the downstream side of the transfer position T, a plurality of conveyance belts 70 that convey the recording medium P onto which the toner image has been transferred toward the second casing 10B are provided in the first casing 10A, and are conveyed to the conveyance belt 70. A transport belt 80 that transports the recording medium P to the downstream side is provided in the second housing 10B.

  Each of the plurality of conveyor belts 70 and the conveyor belt 80 is formed in an annular shape, and is wound around a pair of winding rolls 72. The pair of winding rolls 72 are respectively arranged on the upstream side and the downstream side in the conveyance direction of the recording medium P, and when one of them is driven to rotate, the conveyance belt 70 (conveyance belt 80) moves in one direction (in FIG. 1). Cycle in the clockwise direction.

  A fixing unit 82 for fixing the toner image transferred onto the surface of the recording medium P to the recording medium P with heat and pressure is provided on the downstream side of the conveyance belt 80.

  The fixing unit 82 includes a fixing belt 84 and a pressure roll 88 disposed so as to contact the fixing belt 84 from below. A fixing unit N is formed between the fixing belt 84 and the pressure roll 88 to fix the toner image by pressurizing and heating the recording medium P.

The fixing belt 84 is formed in an annular shape and is wound around the drive roll 89 and the driven roll 90. The drive roll 89 faces the pressure roll 88 from above,
The driven roll 90 is disposed above the drive roll 89.

  Each of the driving roll 89 and the driven roll 90 includes a heating unit such as a halogen heater. As a result, the fixing belt 84 is heated.

  As shown in FIG. 1, a conveyance belt 108 is provided on the downstream side of the fixing unit 82 to convey the recording medium P sent from the fixing unit 82 to the downstream side.

  A cooling unit 110 that cools the recording medium P heated by the fixing unit 82 is provided on the downstream side of the conveyance belt 108.

  The cooling unit 110 includes an absorption device 112 that absorbs the heat of the recording medium P, and a pressing device 114 that presses the recording medium P against the absorption device 112. The absorption device 112 is disposed on one side (upper side in FIG. 1) with respect to the conveyance path 60, and the pressing device 114 is disposed on the other side (lower side in FIG. 1).

  The absorption device 112 includes an annular absorption belt 116 that contacts the recording medium P and absorbs the heat of the recording medium P. The absorption belt 116 is wound around a driving roll 120 that transmits a driving force to the absorption belt 116 and a plurality of winding rolls 118.

  A heat sink 122 made of, for example, an aluminum material is provided on the inner peripheral side of the absorption belt 116 to dissipate the heat absorbed by the absorption belt 116 in contact with the absorption belt 116 in a planar shape.

  Further, a fan 128 for removing heat from the heat sink 122 and discharging hot air to the outside is disposed on the back side of the second housing 10B (the back side of the paper surface shown in FIG. 1).

  The pressing device 114 that presses the recording medium P against the absorbing device 112 includes an annular pressing belt 130 that conveys the recording medium P while pressing the recording medium P against the absorbing belt 116. The pressing belt 130 is wound around a plurality of winding rolls 132.

  On the downstream side of the cooling unit 110, there is provided a correction device 140 that conveys the recording medium P and corrects the curl of the recording medium P.

  An image reading device (built-in image sensor 200) that detects a toner density defect, an image defect, an image position defect, and the like of the toner image fixed on the recording medium P is provided on the downstream side of the correction device 140. Details of the built-in image sensor 200 will be described later.

  The toner density defect may be caused by the following factors.

(Factor 1) Change in toner density due to changes in temperature and humidity of the space (room) in which the image forming apparatus 10 is installed (environmental changes and machine differences)
(Factor 2) Change in toner density due to aging of parts (Factor 3) Difference in toner density due to machine differences in parts (Factor 4) Color conversion error

  On the downstream side of the built-in image sensor 200, a discharge roll 198 that discharges the recording medium P having an image formed on one side thereof to a discharge unit 196 attached to the side surface of the second housing 10B is provided.

  On the other hand, when images are formed on both sides, the recording medium P sent from the built-in image sensor 200 is conveyed to a reversing path 194 provided on the downstream side of the built-in image sensor 200.

  The reversing path 194 includes a branch path 194A that branches from the transport path 60, a paper transport path 194B that transports the recording medium P transported along the branch path 194A toward the first housing 10A, and a paper transport path. A reversing path 194 </ b> C is provided that turns the recording medium P conveyed along 194 </ b> B in the reverse direction to switch back and reverse the recording medium P.

  With this configuration, the recording medium P that is switched back and conveyed by the reverse path 194C is conveyed toward the first housing 10A, and further enters the conveyance path 60 provided above the recording medium container 48, and is transferred to the transfer position. It is sent to T again.

(Built-in image sensor 200)
The image forming apparatus 10 according to the present embodiment includes a built-in image sensor 200. The built-in image sensor 200 is used for detecting whether or not there is an abnormality in the image formed on the recording medium P by the image forming unit 16.

  The built-in image sensor 200 in this case has a function as a means for measuring gradation reproducibility and color reproducibility of the image forming unit 16. In addition, in order to maintain the function as the measurement unit normally, the built-in image sensor 200 may be calibrated regularly or irregularly.

  In the following description, the length direction of the image forming apparatus 10 (sub-scanning direction that is the conveyance direction of the recording medium P) is the X direction, the height direction of the apparatus is the Y direction, and the depth direction of the apparatus (main scanning direction) is Z. The direction is assumed (see FIGS. 1 and 2).

  As shown in FIG. 2, the built-in image sensor 200, which is an example of an image reading device, includes an illumination unit 202 that emits light toward a recording medium P on which an image is recorded, and a recording medium that is irradiated from the illumination unit 202. An imaging unit 208 having an imaging optical system 206 that forms an image of light reflected by P on a CCD sensor 204 as an example of a reading unit, and various standards and the like when using the built-in image sensor 200 or during calibration. And a setting unit 210 provided.

  The CCD sensor 204 according to the present embodiment includes a plurality of light receiving elements (for example, photodiodes) arranged along a direction corresponding to the main scanning direction, and a red image sensor and a green image sensor. An image sensor and a blue image sensor are provided. Each color image sensor is provided with a filter that transmits light of each color component on the light receiving surface of the light receiving element. Each color image sensor outputs, as a signal, the electric charge accumulated according to the amount of each color component of the light received by the light receiving element.

  The illumination unit 202 is disposed on the upper side of the conveyance path 60 of the recording medium P, and has a pair of a first lamp 212A and a second lamp 212B (hereinafter collectively referred to as “long” in the Z direction (main scanning direction)). , Sometimes referred to as “lamp 212”).

  As the lamp 212, for example, a fluorescent lamp, a xenon lamp, a plurality of white LEDs arranged along the main scanning direction, and the like are used. In the present embodiment, a plurality of white LEDs (not shown) are used. . In the present embodiment, the lamp 212 is configured by arranging a plurality of LED substrates (not shown) on which one or more white LEDs are mounted in the main scanning direction. Of course, the substrate on which the plurality of white LEDs are mounted may be a single substrate.

  Further, the length of the irradiation range of the lamp 212 is set larger than the width of the maximum recording medium P to be conveyed. The lamp 212 is arranged symmetrically with respect to the optical axis OA (designed optical axis) that is reflected by the recording medium P and travels toward the image forming unit 208. More specifically, the lamps 212 are arranged symmetrically with respect to the optical axis OA so that the irradiation angle to the recording medium P is, for example, not less than 45 ° and not more than 50 °.

Specifically, the pair of lamps 212 are arranged along the conveyance path 60 of the recording medium P, and are recorded on the first lamp 212A and the first lamp 212A arranged on the upstream side in the conveyance direction of the recording medium P. And a second lamp 212B disposed on the downstream side in the conveyance direction of the medium P.
Then, the light irradiated from the first lamp 212A and the second lamp 212B is irradiated to the irradiation position D of the transparent window glass 286 on the transport path 60 between the first lamp 212A and the second lamp 212B. It is configured. In the window glass 286, the irradiation area irradiated with light from the lamp 212 is an area that overlaps the area through which the image forming area of the recording medium P passes on the setting unit 210, and is formed on the recording medium P on the conveyance path 60. An area in which the obtained image is read by the CCD sensor 204 is configured to include a predetermined area (image reading area).

  The imaging optical system 206 also reflects the light guided along the optical axis OA in the X direction (in the present embodiment, downstream in the transport direction of the recording medium P), and the first mirror 214. The second mirror 216 that reflects the light reflected by the second mirror 216 upward, the third mirror 218 that reflects the light reflected by the second mirror 216 upstream in the transport direction of the recording medium P, and the light reflected by the third mirror 218 A lens 220 that focuses (images) the CCD sensor 204 is configured as a main part. The CCD sensor 204 is arranged on the upstream side in the transport direction of the recording medium P with respect to the optical axis OA.

  The length of the first mirror 214 in the Z direction is larger than the width of the maximum recording medium P. The first mirror 214, the second mirror 216, and the third mirror 218 are respectively focused (condensed) while reflecting the reflected light of the recording medium P incident on the imaging optical system 206 in the Z direction (main scanning direction). ) It is designed to reflect. Thus, the reflected light from each part in the width direction of the recording medium P is incident on the substantially cylindrical lens 220.

  The built-in image sensor 200 is configured such that the CCD sensor 204 outputs (feeds back) the imaged light, that is, a signal corresponding to the image density, to the control device 20 (see FIGS. 1 and 4) of the image forming apparatus 10. Has been. In addition to the control device 20 of the image forming apparatus 10, a control device that controls the built-in image sensor 200 may be provided separately. “Providing separately” includes not only structurally separate substrates but also separation of components that are commonly controlled by the substrates.

  The control device 20 performs processing for correcting an image formed in the image forming unit 16 based on a signal input from the built-in image sensor 200. As an example of processing for correcting an image, correction of a tone adjustment LUT (lookup table) of the image forming apparatus 10 can be given.

  Other examples of correction include correction of the intensity of irradiation light by the exposure apparatus 40 based on a signal input from the built-in image sensor 200, the image formation position, and the like, and correction of the development potential and transfer current value.

  In addition, a light amount diaphragm unit 224 (224L, 224S, 224U)) is provided between the third mirror 218 and the lens 220 in the imaging optical system 206. The light amount diaphragm unit 224 narrows the light amount of light that forms an image on the CCD sensor 204 across the optical path in the Z direction in the Y direction (direction intersecting with the main scanning direction), and adjusts the amount of light diaphragm by operating from the outside. It is configured freely. The amount of light reduced by the light amount restrictor 224 is adjusted so that the amount of light imaged on the CCD sensor 204 is equal to or greater than a predetermined amount even if the light emission amount of the lamp 212 changes over time.

  The built-in image sensor 200 includes a control circuit 100 provided with a circuit board 262 for controlling a reference roll rotation motor 22 (see FIG. 4) which is a motor for rotating a reference roll 226 described later.

  The setting unit 210 includes a reference roll 226 that is long in the Z direction. The reference roll 226 is formed in a polygonal cylindrical shape in which a predetermined number of faces are formed in the circumferential direction. However, as shown in FIG. 3, the reference roll 226 according to the present embodiment has 10 faces. It is a polygonal cylinder.

  As shown in FIGS. 2 and 3, the reference roll 226 has a detection reference surface 228 (basic color is black) directed toward the conveyance path 60 when the image of the recording medium P is detected, and recording by the built-in image sensor 200. And a retracting surface 230 directed toward the transport path when the image detection of the medium P is not performed.

  In addition, the reference roll 226 is a reference surface (white reference surface 232, yellow reference surface 234, cyan reference surface 237, magenta color reference surface 239, red reference surface 231 and green reference surface) used for color gamut correction processing described later. A surface 233 and a blue reference surface 235) and a composite inspection surface 236 on which a plurality of inspection patterns are formed. In the following, when the reference plane of each color is not distinguished, it may be simply referred to as “color reference plane”.

  The reference roll 226 is configured to switch the surface to be directed to the conveyance path 60 side by rotating around the rotation shaft 226A. The surface of the reference roll 226 is switched by the control circuit 100 provided on the circuit board 262.

  Further, the reference roll 226 is formed in a decagonal cylindrical shape, so that a difference in distance from the rotation center between the center in the circumferential direction of each surface and the corner portion between the surfaces is suppressed. Thus, the corners between the surfaces of the reference roll 226 do not interfere with the illumination unit 202 while keeping the distance between each surface of the reference roll 226 and the irradiation position (window glass 286) of the lamp 212 small.

  The detection reference surface 228 has a circumferential width smaller than that of the other surfaces, and is a position reference surface that positions the detected (read) surface of the conveyed recording medium P at the irradiation position by the lamp 212. ing. In some cases, the circumferential surface of the reference roll 226 is 12 or more, and the circumferentially opposite sides of the detection reference surface 228 are guide surfaces that do not have the above-described functions as a reference.

  The retracting surface 230 has a circumferential width larger than that of other surfaces. The retraction surface 230 is a guide surface that guides the recording medium P when the built-in image sensor 200 does not detect the image of the recording medium P, and the distance from the axis of the rotation shaft 226A is more than the detection reference surface 228. It is said to be small. Accordingly, when the image detection of the recording medium P by the built-in image sensor 200 is not performed, the distance from the illumination unit 202 (window glass 286) is larger than when the image detection of the recording medium P is performed by the built-in image sensor 200. A wide conveyance path is formed.

  The composite inspection surface 236 is formed by arranging a position adjustment pattern for correcting the position in the rotation direction of the reference roll 226 (the conveyance direction of the recording medium P), a focus detection pattern, and a depth detection pattern on the same surface. ing.

  The white reference surface 232 is a reference surface for correcting lightness unevenness in the main scanning direction caused by the lamp 212 or the CCD sensor 204, that is, so-called shading correction, and is configured by adhering a white film, for example. . When the irradiation light from the lamp 212 is applied to the white reference surface 232, the reflected light reflected by the white reference surface 232 is input to the CCD sensor 204 via the imaging optical system 206 as a read signal. .

  Each color reference plane (white reference plane 232, yellow reference plane 234, cyan reference plane 237, magenta reference plane 239, red reference plane 231, green reference plane 233, and white reference plane 232 in the present embodiment) The blue reference surface 235) is used as a reference surface (color sample) for correcting hue / saturation unevenness in the main scanning direction caused by the lamp 212 or the CCD sensor 204. Each color reference surface is configured by attaching a film of each color, for example. When the irradiation light from the lamp 212 is applied to each color reference surface, the reflected light reflected by each color reference surface is input to the CCD sensor 204 via the imaging optical system 206 as a read signal.

  FIG. 4 is a block diagram showing a control system in the image forming apparatus 10 according to the present embodiment.

  As described above, the control device 20 has a function of correcting an image formed in the image forming unit 16 based on a signal from the built-in image sensor 200. The control device 20 also has a function of controlling calibration of the built-in image sensor 200 (for example, calibration of the CCD sensor 204 described above).

  More specifically, as shown in FIG. 4, the control device 20 includes a CPU (Central Processing Unit) 20A, a ROM (Read Only Memory) 20B, a RAM (Random Access Memory) 20C, an NVM (Non Volatile Memory) 20F, and An input / output port 20D is provided. Each is connected to each other via a bus 20E such as an address bus, a data bus, and a control bus.

  Various programs are stored in the ROM 20B, and various controls are performed by the CPU 20A reading the programs from the ROM 20B, developing them in the RAM 20C, and executing them.

  The NVM 20F is a nonvolatile storage medium that stores various types of information that must be retained even when the power switch of the apparatus is turned off.

  A user interface (UI) panel 30, a dimming circuit 370, a control circuit 100, and a read signal processing unit 350 are connected to the input / output port 20D.

  The UI panel 30 includes, for example, a touch panel display in which a transmissive touch panel is superimposed on a display. Various types of information are displayed on the display surface of the display, and information and instructions are received when the user touches the touch panel. In the present embodiment, an example in which the UI panel 30 is applied is described. However, the present invention is not limited to this, and a display unit such as a liquid crystal display and an operation unit provided with a numeric keypad, operation buttons, and the like are provided. It is good also as a form provided separately.

  The dimming circuit 370 is a circuit that continuously changes the brightness of the lamp 212 by controlling the current passed through the white LED constituting the lamp 212 when performing dimming reading of each color reference surface described later. In the present embodiment, “dimming reading” means that the current supplied to the white LED is changed at a predetermined stage to dim the lamp 212, and the reflected light from each color reference surface in the dimming state at each stage. Is read by the CCD sensor 204.

  Further, as described above, the control circuit 100 controls switching of each surface (the detection reference surface 228, the retreat surface 230, the composite inspection surface 236, and each color reference surface) of the reference roll 226. More specifically, the driving of the reference roll rotation motor 22 connected to the control circuit 100 is controlled based on an instruction from the control device 20.

  On the other hand, the read signal processing unit 350 performs at least various calibrations and color gamut correction processes for the built-in image sensor 200 connected to the read signal processing unit 350 in accordance with instructions from the control device 20.

  Examples of the calibration of the built-in image sensor 200 include offset and gain correction for correcting the output upper and lower limit values of the CCD sensor 204.

  Further, shading correction that corrects the lightness distribution in the main scanning direction of the image data based on the profile of the image data obtained by reading the white reference surface 232 can be given.

  Furthermore, correction of hue / saturation unevenness in the main scanning direction for the image data, which is performed based on the profile of the image data obtained by reading each color reference plane, can be mentioned.

  Each of the above components constituting the read signal processing unit 350 according to the present embodiment is controlled by a control signal (not shown) from the CPU 20A input via the input / output port 20D.

  By the way, in the built-in image sensor 200, as one aspect of correction (calibration), color correction is performed on image data based on a read value obtained by reading an image formed on the recording medium P, that is, in addition to brightness. Hue / saturation correction may be performed.

  This is because even if the read value is obtained by reading the same image, a difference in hue / saturation is generated for each built-in image sensor 200 due to a machine difference of the illumination unit 202 or the CCD sensor 204 or a change with time.

  That is, for example, due to a difference in sensitivity caused by a manufacturing deviation of the filter of the CCD sensor 204 or a change in sensitivity due to a change in the filter over time, the reading value as image data for each built-in image sensor 200 may be different from each other or over time. This is because there is a possibility that a change occurs.

  As one method of the above correction, there is a method using a test chart including gradation patch images of component colors with known color characteristics formed on photographic paper or the like. A method of measuring a color by reading the test chart with the built-in image sensor 200 or the like, and calculating a color conversion coefficient for converting image data obtained by the color measurement into target reference image data corresponding to the test chart It is.

When the built-in image sensor 200 performs reading by the CCD sensor 204, the built-in image sensor 200 outputs image data obtained by correcting the read image data or the like with the calculated color conversion coefficient. However, in this method, there is an inconvenience that a test chart for a plurality of colors must be used for each correction. In addition, the test chart itself that needs to strictly manage the color difference is expensive, and the color difference of the test chart changes over time (for example,
(Discoloration).

  Therefore, in the image forming apparatus 10 according to the present embodiment, as one aspect of the calibration process, brightness, hue, and saturation (that is, color gamut) are corrected using each color reference plane. In this case, sensitivity adjustment and read value of the CCD sensor 204 are directly corrected.

  Note that a reading value obtained by irradiating each color reference surface while adjusting the irradiation light from the lamp 212 and reading the reflected light by the CCD sensor 204 (hereinafter, this reading value may be referred to as a “dimming reading value”). And, based on the dimming read value, when the image formed by the image forming apparatus 10 or the like is read by the built-in image sensor 200, the color gamut difference for each built-in image sensor 200 is corrected. It may be.

  The problem here is dust adhering to each color reference surface. Since the proper correction is hindered by the presence of dust, it is necessary to confirm in advance whether dust has adhered.

  On the other hand, a window glass 286 is provided on the optical path along the optical axis OA (see FIG. 3) described above, and dust may adhere to the window glass 286.

  For example, when black dust is attached to the white reference surface 232, a significant difference appears in the detection signal from the CCD sensor 204 depending on the presence or absence of dust. Detection of black dust is easy.

  If the detection of dust is limited to the window glass 286, white dust and black dust can be discriminated by using the white reference surface 232 and the detection reference surface 228 in combination. In this case, it is preferable to turn on the lamp 212. When the lamp 212 is turned off, the read value becomes 0 when there is no light and the image is completely dark.

  However, the reference roll applied to this embodiment includes an achromatic color reference surface (white reference surface 232, detection reference surface 228 (black), and chromatic color reference surface (yellow reference surface 234, cyan). Color reference surface 237, magenta color reference surface 239, red reference surface 231, green reference surface 233, and blue reference surface 235), in particular, whether or not dust adheres to the chromatic color reference surface, and In other words, if dust adheres to the chromatic color reference plane, there may not be a significant difference in density, and the presence / absence of dust adhesion and the location determination are achromatic. It is difficult compared to the reference plane.

  Therefore, in the present embodiment, an algorithm capable of determining whether dust (white dust, black dust) adheres to each reference surface and determining whether the existing dust is the reference surface or the window glass 286. Established.

  FIG. 5 is a functional block specialized for dust identification control executed by the control device 20 of the present embodiment. Note that FIG. 5 shows the functions executed mainly by the CPU 20 </ b> A of the control device 20, which are specialized for dust identification control and are grouped by function, and do not limit the hardware configuration of the control device 20. Moreover, you may make it comprise the control apparatus (for example, ASIC) only for dust specific control.

  As shown in FIG. 5, the control device 20 related to dust identification control includes an information collection unit 250 and an analysis processing unit 252.

  The UI panel 30 is connected to the reception unit 254 of the information collection unit 250. When the reception unit 254 receives an instruction to execute the dust identification control by operating the UI panel 30, the reference panel selection unit 256 is activated.

  The reference plane selection unit 256 is connected to the drive pulse signal output unit 258 and the processing status monitoring unit 260. When activated, the reference plane selection unit 256 selects the reference planes in a predetermined order. Although the order of selection is not particularly determined, it is efficient to follow the circumferential order of the reference rolls 226. As an example, the white reference surface 232 → the green reference surface 233 → the yellow reference surface 234 → the blue reference surface 235. → Cyan reference plane 237 → detection reference plane 228 (black) → magenta reference plane 239 → red reference plane 231 or vice versa. In this case, it is good also as the last of the selection order of the detection reference plane 228 (black) applied to the following process (image reading process).

  The order of the achromatic color reference plane → the chromatic color reference plane, or the order of the chromatic color reference plane → the achromatic color reference plane may be used.

  The reference plane selection information selected by the reference plane selection unit 256 is sent to the drive pulse signal output unit 258 and the processing status monitoring unit 260.

  The drive pulse signal output unit 258 outputs a drive pulse signal for rotating the reference roll rotation motor 22 to the control circuit 100. As a result, the control circuit 100 drives the reference roll rotation motor 22 to place the selected reference plane on the OA optical axis (opposite the window glass 286).

  The control circuit 100 recognizes the driving state of the reference roll rotation motor 22 and outputs a positioning completion signal for positioning the selected reference surface to the positioning confirmation unit 261. In addition, the positioning confirmation unit 261 arranges a rotation position sensor that detects that each reference surface is positioned on the optical axis OA around the reference roll rotation motor 22 and receives a signal from the rotation position sensor. It may be.

  The positioning confirmation unit 261 is connected to the processing status monitoring unit 260 and the selection reference plane reading instruction unit 264. The positioning confirmation unit 261 outputs positioning completion information of a specific reference surface to the processing status monitoring unit 260 and instructs the selected reference surface reading instruction unit 264 to start reading by the CCD sensor 204. .

  Upon receipt of the reading execution start instruction, the selected reference plane reading instruction unit 264 controls the reading signal processing unit 350 to read the image of the positioned reference plane by the CCD sensor 204.

  The read signal processing unit 350 sends the reference plane image information read by the CCD sensor 204 to the read image information collecting unit 268.

  Further, the reading signal processing unit 350 feeds back the end information to the selection reference plane reading instruction unit 264 every time the reading process ends. The selection reference plane reading instruction unit 264 instructs the reading signal processing unit 350 to execute reading a predetermined number of times (N times). In the present embodiment, the number of readings N for one reference plane is set to five.

  Further, this image reading is executed for each color component of RGB. Although details will be described later, in the dust discrimination, a color component that is complementary to the color of the reference surface is used (white dust) or a complementary color depending on the type of dust (white dust or black dust). Unrelated color components are used (black dust).

  White dust and black dust indicate relatively different reflectances. White dust means a relatively high reflectance, and black dust means a relatively low reflectance. For example, with gray (intermediate gradation) as a boundary, a region having a lower reflectance than the gray may be black dust, and a region having a higher reflectance than the gray may be white dust. Gray may belong to any.

  The selection reference plane reading instruction unit 264 outputs a calculation instruction to the read image information collecting unit 268 when N reading instructions are completed to the reading signal processing unit 350.

  When receiving the calculation instruction, the read image information collecting unit 268 collects N times (in this embodiment, 5 times) of read image information, and the intensity (density value) of the read image information for N times. ) Are simply added, and the added data is sent to the difference data calculation unit 270. The read image information collection unit 268 sends an end signal to the processing status monitoring unit 260 every time one addition operation (addition operation for each reference surface) is completed.

  The processing status monitoring unit 260 receives reference surface selection information from the reference surface selection unit 256, receives positioning end information from the positioning confirmation unit 261, and receives calculation end information from the read image information collection unit 268. The image reading process for the reference surface is monitored, the image reading process timing for the next reference surface is grasped, and the next reference surface selection instruction is sent to the reference surface selection unit 256.

  The difference data calculation unit 270 converts the added data into difference data for adjacent information (pixels) and sends the difference data to the standardized data calculation unit 272.

  The standardized data calculation unit 272 calculates standardized data for each color component (red (r), green (g), blue (b)) from the difference data, and stores it in the data storage unit 274. Thus, the data storage unit 274 stores standardized data for each reference plane. For example, Kr, Kg, and Kb are calculated as standardized data for the detection reference surface 228 (black), and Wr, Wg, and Wb are calculated as standardized data for the white reference surface 232. The same applies to the chromatic color reference plane.

  Standardized data is obtained for each color component, and the color component that most significantly expresses dust adhesion is selected. For example, as for white dust on the yellow reference surface 234, dust adhesion is most prominently represented by a blue component (b component) that is complementary to the color of the yellow reference surface 234 (yellow).

  On the other hand, as for black dust on the yellow reference surface 234, the red component (r component) that is not in a complementary relationship with the color (yellow) of the yellow reference surface 234 is most significantly expressed as dust.

  For the yellow reference plane 234, a green component (G component) may be used as a color component that has no complementary color relationship.

  In the data storage unit 274, in addition to all data, that is, an achromatic color reference plane (white reference plane 232, detection reference plane 228 (black), a chromatic color reference plane (yellow reference plane 234, cyan reference plane) 237, the magenta color reference surface 239, the red reference surface 231, the green reference surface 233, and the blue reference surface 235), the signal indicating that the data is complete (storage completion signal) is sent to the processing status monitoring unit 260. Send it out.

  When receiving the storage completion signal, the processing status monitoring unit 260 instructs the data reading unit 276 to read the standardized data of each reference plane from the data storage unit 274 (reading instruction).

  In response to the reading instruction, the data reading unit 276 reads the standardized data for each reference plane from the data storage unit 274 and sends the standardized data for each reference plane to the analysis unit 278 of the analysis processing unit 252.

  In the analysis unit 278, for example, standardized data is collated between a plurality of color reference planes. The collation includes the presence / absence of output that is assumed to be dust and the determination of the consistency of positions based on a plurality of criteria.

  The analysis unit 278 is connected to the analysis result determination unit 280 and determines based on the analysis result, that is, the presence / absence, type, and position of dust.

  For example, the chart shown in FIG. 11 lists the result of collation between the yellow reference surface 234 and the detection reference surface 228 (black), the collation between the yellow reference surface 234 and the white reference surface 232, and the result of the determination. (Details will be described later).

  The analysis result determination unit 280 is connected to the notification information output unit 282. The notification information output unit 282 receives the analysis result determination unit 280, selects a message to be notified to the user, and displays the message on the display surface of the UI panel 30.

  For example, “There is white dust of area s around the coordinates (x, y) of the window glass. ”And“ Black dust of area s is attached around the coordinates (x, y) of the white reference plane. Is displayed. The coordinates may be numerical values or may be ambiguous expressions such as “on the diagonal” or “upper left corner”. The area may be a numerical value or the number of pixels.

  The operation of the present embodiment will be described below.

  First, the image forming process of the image forming apparatus 10 will be described.

The image data that has been subjected to image processing by the image signal processing unit 13 is sent to each exposure device 40.
In each exposure device 40, each light beam L is emitted according to image data, and is exposed to each image carrier 18 charged by a scorotron charger, thereby forming an electrostatic latent image.

  The electrostatic latent image formed on the image carrier 18 is developed by the developing device, and the first special color (V), the second special color (W), yellow (Y), magenta (M), and cyan (C). A toner image of each color of black (K) is formed.

As shown in FIG. 1, each color toner image formed on the image carrier 18 of each of the image forming units 16V, 16W, 16Y, 16M, 16C, and 16K has six primary transfer rolls 36V,
Multiple transfer is sequentially performed on the intermediate transfer belt 34 by 36W, 36Y, 36M, 36C, and 36K.

  The color toner images transferred onto the intermediate transfer belt 34 are secondarily transferred onto the recording medium P conveyed from the recording medium container 48 by the secondary transfer roll 62. The recording medium P onto which the toner image has been transferred is transported toward the fixing unit 82 provided inside the second housing 10B by the transport belt 70.

  The toner images of the respective colors on the recording medium P are fixed on the recording medium P by being heated and pressurized by the fixing unit 82. Further, the recording medium P on which the toner image is fixed is cooled by passing through the cooling unit 110 and then sent to the correction device 140 to correct the curvature generated in the recording medium P.

  The recording medium P whose curvature is corrected is discharged to the discharge unit 196 by the discharge roll 198 after an image defect or the like is detected by the built-in image sensor 200.

  On the other hand, when an image is formed on a non-image surface where no image is formed (in the case of double-sided printing), the recording medium P is reversed by the reversing path 194 after passing through the built-in image sensor 200. Then, the toner is fed into a conveyance path 60 provided above the recording medium accommodating portion 48, and a toner image is formed on the back surface in the above-described procedure.

  In the image forming apparatus 10 according to the present embodiment, components for forming images of the first special color and the second special color (image forming units 16V and 16W, exposure devices 40V and 40W, toner cartridges 14V and 14W). The primary transfer rolls 36V and 36W) are configured to be attachable to the first housing 10A as additional parts according to the user's selection. Therefore, the image forming apparatus 10 does not have a component for forming the first special color and second special color images, and the image of any one of the first special color and the second special color. It is good also as a structure which has only the components for forming.

  Next, the built-in image sensor 200 detects a toner density defect (see Factor 1 to Factor 4 described above), an image defect, an image position defect, and the like of the toner image fixed on the recording medium P.

  The toner density defect is corrected by reading the toner image with the built-in image sensor 200 and feeding back to the image forming unit with respect to environmental changes and machine differences, part deterioration over time, and part machine differences (factor 1 to factor 3). To do.

  Further, the toner density defect is caused by, for example, converting the image data (RGB) received at the time of image formation into an L * a * b * color space or the like in response to the color conversion error (factor 4). The image is converted into cmyk, which is an image, and there may be a color if it is reproduced during the color conversion process. Therefore, the toner image is read by the built-in image sensor 200, fed back to the image forming unit, and corrected so as to achieve proper color conversion.

  Further, the image defect performs feedback correction for interpolating with surrounding image data, and the image position defect performs feedback correction for changing the image position.

  By the way, the feedback correction by the built-in image sensor 200 is based on the premise that the color (lightness, hue, saturation) is properly read by the CCD sensor 204.

  However, due to a difference in sensitivity due to a manufacturing deviation of the filter of the CCD sensor 204 or a change in sensitivity due to a change in the filter over time, the reading value as image data for each built-in image sensor 200 is different from that of the machine. Changes may occur.

  Therefore, the built-in image sensor 200 corrects brightness, hue, and saturation (that is, color gamut) using each color reference plane as one aspect of the calibration process. In this case, sensitivity adjustment and read value of the CCD sensor 204 are directly corrected.

  Note that a reading value obtained by irradiating each color reference surface while adjusting the irradiation light from the lamp 212 and reading the reflected light by the CCD sensor 204 (hereinafter, this reading value may be referred to as a “dimming reading value”). And, based on the dimming read value, when the image formed by the image forming apparatus 10 or the like is read by the built-in image sensor 200, the color gamut difference for each built-in image sensor 200 is corrected. It may be.

(Dust detection)
When the built-in image sensor 200 is calibrated, it is necessary to check whether dust adhering to each color reference plane and / or the window glass 286 has adhered.

  In the present embodiment, an algorithm is established that can determine whether dust (white dust, black dust) adheres to each reference surface and whether the existing dust is a reference surface or a window glass 286. did.

  FIG. 6 is a flowchart showing a dust identification control routine executed by the control device 20.

  In step 400, a reference plane is selected. The order of selection is not particularly limited, but the order of rotation direction is preferable in terms of efficiency. That is, as an example, white reference plane 232 → green reference plane 233 → yellow reference plane 234 → blue reference plane 235 → cyan reference plane 237 → detection reference plane 228 (black) → magenta reference plane 239 → red reference plane 231. Alternatively, selection is made in the reverse order.

  When the reference plane is selected in step 400, in the next step 402, the reference roll rotation motor 22 is driven and positioning is performed so that the selected reference plane faces the window glass 286.

  In the next step 404, it is determined whether or not the positioning is completed. If an affirmative determination is made, the process proceeds to step 406 to instruct the start of image reading, and the process proceeds to step 408.

  In step 408, the image reading process is executed by the CCD sensor 204 of the built-in image sensor 200, and the process proceeds to step 410 for each reading process.

  In step 410, it is determined whether or not the number of readings has reached N times (in this embodiment, 5 times). If a negative determination is made, the process returns to step 406 to repeat the above process (reading process). If the determination in step 410 is affirmative, it is determined that N reading processes have been completed, and the process proceeds to step 412.

  In step 412, N times of read information (each RGB color component) is added to obtain added data, and then the process proceeds to step 414, where an operation for obtaining difference data is executed based on the added data.

  In the next step 416, an operation for obtaining standardized data is executed based on the difference data, and the process proceeds to step 418.

  In step 418, the standardized data is stored, and the process proceeds to step 420. In step 420, it is determined whether or not the storage of standardized data for all reference planes has been completed. If the determination is negative, it is determined that there is a reference plane in which no standardized data is stored, and the process returns to step 400, Repeat the process.

  If the determination in step 420 is affirmative, it is determined that the storage of standardized data for all reference planes has been completed, and the process proceeds to step 422, which is the starting point of the dust detection process.

  In step 422, the type of dust to be detected (white dust, black dust) is selected, and then the process proceeds to step 424, the chromatic color reference plane to be analyzed is selected, and the process proceeds to step 426.

  In step 426, standardized data of a specific color component on the selected chromatic color reference plane is read, and the process proceeds to step 428.

  In step 428, standardized data of the same color component as the specific color component on the achromatic reference surface (white or black) for detecting the type of the selected dust is read, and the process proceeds to step 430.

  In step 430, collation of standardized data is executed, and then in step 432, it is determined whether dust has been detected based on the collation result of standardized data.

  If an affirmative determination is made in step 432, the process proceeds to step 434 to determine the location of the detected dust (on the reference surface or the window glass surface), and then the process proceeds to step 436 to notify the dust information (for example, Message display), and the process proceeds to step 438. In step 438, calibration processing based on the attached dust is executed, and the process proceeds to step 440.

  The message to be notified to the user is displayed on the display surface of the UI panel 30. For example, “white dust having an area s around the coordinates (x, y) of the window glass is attached. ”And“ Black dust of area s is attached around the coordinates (x, y) of the white reference plane. Is displayed. Not only the coordinates but also an ambiguous expression such as “on the diagonal” or “upper left corner” may be used.

  If the determination in step 432 is negative, it is determined that no dust has been detected, and the process proceeds to step 440.

  In step 440, it is determined whether or not to continue the process. If an affirmative determination is made in step 440, the process returns to step 432 and the above steps are repeated.

  The continuation of processing here includes both change of the kind of dust on the same reference plane and change to a different reference plane. For example, when the yellow reference plane 234 is first selected and the execution of the white dust detection process is completed, the continuation of the process is the black dust detection process on the same yellow reference plane 234.

  In addition, when the yellow reference surface 234 is selected and the execution of the white dust detection process and the black dust detection process is finished, the process continues when the white color detection of the reference surface of the next color (for example, the blue reference surface 235) is performed. Processing or black dust detection processing.

  On the other hand, if a negative determination is made in step 440, it is determined that all processing has been completed, and this routine ends.

  Hereinafter, taking the yellow reference surface 234 as an example, more specific to the control (mainly from step 426 to step 438) from collation of normalized data and from dust detection to notification in the dust identification control according to the flowchart of FIG. A detailed procedure will be described.

Example 1
“Detecting white dust using the yellow reference surface 234 and the detection reference surface 228 (black)”
FIG. 7 is a flowchart showing a white dust detection and calibration execution control routine using the yellow reference surface 234 and the detection reference surface 228 (black).

  In step 450W of FIG. 7, standardized data Yb of the blue component of the yellow reference plane 234 is read, and then the process proceeds to step 452W to read standardized data Kb of the blue component of the detection reference plane 228 (black), and the process proceeds to step 454W. .

  In step 454W, it is determined as a result of the analysis of the standardized data Yb whether or not it is determined that there is dust.

  If an affirmative determination is made in step 454W, the process proceeds to step 456W. If a negative determination is made, the process proceeds to step 458W. In each step 456W, 458W, the result of analysis of the standardized data Kb is determined to be “with dust”. It is determined whether or not.

  Here, if an affirmative determination is made in step 454W and an affirmative determination is made in step 456W, the process proceeds to step 460W, and it is determined whether or not the positions of dust in the standardized data Yb and the standardized data Kb match.

  As a result of the determinations in steps 454W, 456W, 458W and step 460W, the following determination results 1 to 4 (steps 462W, 464W, 466W, 468W) and normal determination are classified into five types.

  (Determination result 1) Since dust was not detected by the standardized data Yb but dust was detected by the standardized data Kb, it is determined that white dust is attached to the detection reference surface 228 (black) (step 454W → step 458W → step 462W).

  (Determination result 2) Since dust is detected in both the standardized data Yb and the standardized data Kb, and the positions of the two dusts coincide with each other, it is determined that white dust is attached to the surface of the window glass 286 ( Step 454W → Step 456W → Step 460W → Step 464W).

  (Judgment result 3) Dust is detected by both the standardized data Yb and the standardized data Kb. However, since the positions of the two dusts do not coincide with each other, both the yellow reference surface 234 and the detection reference surface 228 (black) are white. It is determined that dust is attached (Step 454W → Step 456W → Step 460W → Step 466W).

  (Determination result 4) Since dust is detected with the standardized data Yb and dust is not detected with the standardized data Kb, it is determined that white dust is attached to the yellow reference surface 234 (step 454W → step 456W → step 468W).

  In addition, when dust is not detected in both the standardized data Yb and the standardized data Kb, it is naturally judged that there is no dust (step 454W → step 458W → step 480W).

  When the determination (steps 462W, 464W, 466W, 468W) ends, the process proceeds to step 470W. In the case of normal determination, the process proceeds from step 458W to step 480W.

  In step 470W, the position and size of the attached image of dust (white dust) are calculated, and then the process proceeds to step 472W to determine whether calibration processing is possible. For example, if it is determined that the dust does not affect the calibration or is less than or equal to the predetermined influence level, it is determined that the calibration process is possible, and the process proceeds to step 474W.

  If a negative determination is made in step 472W, that is, if it is determined that the calibration process is not possible, the process proceeds to step 476W to display information regarding the determination and a message prompting dust removal, and this routine ends.

  In step 474W, the design is designed for the purpose of calculating the correction amount of the image forming condition of the image forming unit, and the overlap between the test chart printed from the image forming unit and the dust is displayed, and then the process proceeds to step 478W to perform calibration. Wait for an instruction to process.

  If there is an instruction to enable the calibration process in step 478W, the process proceeds to step 480W to execute the calibration process, and this routine ends. On the other hand, if there is an instruction that the calibration process cannot be performed in step 478W, the calibration process is not executed, and this routine ends.

(Verification of judgment results)
FIG. 8 is a standardized data characteristic diagram when white dust adheres to the yellow reference surface 234. FIG. 8A shows the flow until the standardized data Yb is generated from the B component read signal of the yellow reference plane 234, and FIG. 8B shows the standardized data from the B component read signal of the detection reference plane 228 (black). The flow until Yb is generated is shown.

  The upper characteristic diagram of FIG. 8A is the result of adding the read data for five times on the yellow reference plane 234, and it can be seen that noise A appears prominently around pixel number 50. FIG.

  The characteristic diagram in the middle part of FIG. 8A is difference data, and it can be seen that the noise A has an output difference to the extent that it is noted with respect to the read signals of adjacent pixels.

  The lower characteristic diagram of FIG. 8A is standardized data obtained from the difference data, and it is determined that the noise A is caused by dust.

  Next, the upper characteristic diagram of FIG. 8B is the result of adding the read data for five times on the detection reference plane 228 (black), including pixel number around 50, and no significant noise is generated. I understand.

  The characteristic diagram in the middle part of FIG. 8B is difference data, and it can be seen that there is no output difference to the extent that it is specially noted for the read signals of adjacent pixels.

  The lower characteristic diagram of FIG. 8B is standardized data obtained from the difference data, and it is determined that there is no dust.

  From the results of FIGS. 8A and 8B, it is determined that white dust adheres to the yellow reference surface 234 (determination result 4 in FIG. 7).

  Next, FIG. 9 is a standardized data characteristic diagram when white dust adheres to the window glass 286. FIG. 9A shows the flow until the standardized data Yb is generated from the B component read signal of the yellow reference plane 234, and FIG. 9B shows the standardized data from the B component read signal of the detection reference plane 228 (black). The flow until Yb is generated is shown.

  The upper characteristic diagram of FIG. 9A is the result of adding the read data for five times on the yellow reference plane 234, and it can be seen that noise B appears prominently around pixel number 50. FIG.

  The characteristic diagram in the middle part of FIG. 9A is difference data, and it can be seen that the noise B has an output difference to the extent that it is noted with respect to the read signals of adjacent pixels.

  The lower characteristic diagram of FIG. 9A is standardized data obtained from the difference data, and it is determined that the noise B is caused by dust.

  Next, the upper characteristic diagram of FIG. 9B is a result of adding the read data for five times on the detection reference plane 228 (black), and the noise B ′ appears remarkably around the pixel number 50. I understand.

  The characteristic diagram in the middle part of FIG. 9A is difference data, and it can be seen that the noise B ′ has an output difference to the extent that it is noted with respect to the read signals of adjacent pixels.

  The lower characteristic diagram of FIG. 9A is standardized data obtained from the difference data, and it is determined that the noise B ′ is caused by dust.

  From the results of FIG. 9A and FIG. 9B, both the yellow reference surface 234 and the detection reference surface 228 (black) are present due to the presence of noise B and noise B ′ at the same position (around pixel number 50). It is unlikely that white dust is attached, and it is appropriate to assume that noise B and noise B ′ are caused by the same dust. As a result, it is determined that white dust is attached to the window glass 286 (that is, on the optical path) (determination result 2 in FIG. 7).

(Example 2)
“Detecting black dust using the yellow reference surface 234 and the white reference surface 232”
FIG. 10 is a flowchart showing a black dust detection and calibration processing execution control routine by the yellow reference surface 234 and the white reference surface 232.

  In step 450K of FIG. 10, the standardized data Yr for the red component of the yellow reference plane 234 is read, and then the process proceeds to step 452K to read the standardized data Wr for the red component of the white reference plane 232, and the process proceeds to step 454K.

  In step 454K, it is determined whether or not it is determined that “there is dust” as a result of the analysis of the standardized data Yr.

  If an affirmative determination is made in step 454K, the process proceeds to step 456K. If a negative determination is made, the process proceeds to step 458K. In each step 456K, 458K, the result of analysis of the standardized data Wr is determined as “there is dust”. It is determined whether or not.

  Here, if an affirmative determination is made in step 454K and an affirmative determination is made in step 456K, the process proceeds to step 460K, and it is determined whether or not the position of the dust matches in the standardized data Yr and the standardized data Wr.

  As a result of the determination in the above steps 454K, 456K, 458K and step 460K, the following determination results 1 to 4 (steps 462K, 464K, 466K, 468K) and normal determination are classified into five types.

  (Determination result 1) Dust is not detected from the standardized data Yr, but dust is detected from the standardized data Wr. Therefore, it is determined that black dust is attached to the white reference surface 232 (step 454K → step 458K → step 462K).

  (Determination result 2) Since dust is detected in both the standardized data Yr and the standardized data Wr, and the positions of the two dusts coincide with each other, it is determined that black dust is attached to the surface of the window glass 286 ( Step 454K → Step 456K → Step 460K → Step 464K).

  (Judgment result 3) Dust is detected in both the standardized data Yr and the standardized data Wr, but the positions of the two dusts do not match, so black dust adheres to both the yellow reference surface 234 and the white reference surface 232. (Step 454K → Step 456K → Step 460K → Step 466K).

  (Determination result 4) Since dust is detected with the standardized data Yr and dust is not detected with the standardized data Wr, it is determined that black dust is attached to the yellow reference surface 234 (step 454K → step 456K → step 468K).

  In addition, when dust is not detected in both the standardized data Yr and the standardized data Wr, naturally, it is judged as normal (no dust) (step 454K → step 458K → step 480K).

  When the determination (steps 462K, 464K, 466K, 468K) ends, the process proceeds to step 470K. In the case of normal determination, the process proceeds from step 458K to step 480K.

  In step 470K, the adhesion image position and size of dust (black dust) are calculated, and then the process proceeds to step 472K to determine whether or not calibration processing is possible. For example, if it is determined that the dust does not affect the calibration or is less than or equal to a predetermined influence level, it is determined that the calibration process is possible, and the process proceeds to step 474K.

  On the other hand, if a negative determination is made in step 472K, that is, if it is determined that the calibration process is not possible, the routine proceeds to step 476, where information relating to the determination and a message for prompting dust removal are displayed, and this routine ends.

  In step 474K, the degree of overlap between the test chart and the dust is displayed, and then the process proceeds to step 478K to wait for an instruction on whether or not calibration processing is possible.

  If there is an instruction to enable the calibration process in step 478K, the process proceeds to step 480K to execute the calibration process, and this routine ends. On the other hand, if there is an instruction that the calibration process cannot be performed in step 478K, the calibration process is not executed and the routine ends.

  FIG. 11 is a chart showing the correspondence between the determination results 1 to 4 in FIG. 7 and the determination results 1 to 4 in FIG. 10 based on the analysis of the standardization data Yb and Kb and the standardization data Yr and Wr. According to this embodiment, it is possible to reliably determine the presence or absence of dust attached to the chromatic color reference surface.

(Example 3)
"Each color reference plane and color components that are optimal for black dust detection, and color components that are optimal for white dust detection"
Table 1 shows the reference planes of each color applied in the present embodiment (yellow reference plane 234, cyan reference plane 237, magenta reference plane 239, red reference plane 231, green reference plane 233, and blue reference plane 235). Is a list of color components applied to determine the presence or absence and position of dust (black dust, white dust).

  In any color reference plane, color components that have a complementary color relationship are selected in the case of black dust discrimination, and color components that do not have a complementary color relationship are selected in the case of white dust discrimination.

  By using the color component selection list shown in Experimental Example 3, a color reference surface (cyan color reference surface 237, magenta color reference surface 239, red) other than the yellow reference surface 234 shown in Experimental Example 1 and Experimental Example 2 is used. Also on the reference surface 231, the green reference surface 233, and the blue reference surface 235), it is possible to reliably determine the presence / absence of dust classified as white dust and black dust, and the position when dust is present.

  In the above-described embodiment, an example in which a white reference surface is used as an achromatic color reference surface has been described. However, the present invention is not limited to this. For example, a form using a black reference surface, a gray color reference surface, or the like may be used. In addition, although an example in which a yellow reference surface, a magenta reference surface, a cyan reference surface, a red reference surface, a green reference surface, and a blue reference surface are used as the chromatic color reference surface has been described, the present invention is not limited thereto. I can't. One or a plurality of other color reference planes may be added in consideration of required accuracy of color gamut correction.

L Light beam P Recording medium OA Optical axis 10 Image forming apparatus 10A First housing 10B Second housing 13 Image signal processing unit 14 (14V, 14W, 14Y, 14M, 14C, 14K) Toner cartridge 16 (16V, 16W, 16Y, 16M, 16C, 16K) Image forming unit 18 (18V, 18W, 18Y, 18M, 18C, 18K) Image carrier 20 Controller 20A CPU
20B ROM
20C RAM
20F NVM
20D I / O port 20E Bus 22 Reference roll rotation motor 30 User interface (UI) panel 32 Transfer section 34 Intermediate transfer belt 36 (36V, 36W, 36Y, 36M, 36C, 36K) Primary transfer roll 38 Drive roll 40 (40V, 40W, 40Y, 40M, 40C, 40K) Exposure device 41 Tension applying roll 42 Opposing roll 44 Winding roll 46 Removal device 48 Recording medium storage unit 52 Sending roll 50 Bottom plate 54 Conveying roll 56 Separating roll 60 Conveying path 60A First folding part 60B Second folding section 62 Secondary transfer roll 66 Preliminary path 70 Conveying belt 72 Rolling roll 80 Conveying belt 82 Fixing unit 84 Fixing belt 88 Pressing roll 89 Driving roll 90 Followed roll 100 Control circuit 108 Conveying belt 110 Cooling unit 112 Absorbing device 114 Pressing device 116 Absorbing belt 118 Winding roll 120 Drive roll 122 Heat sink 128 Fan 130 Pressing belt 140 Straightening device 194 Reverse path 194A Branch path 194B Paper transport path 194C Reverse path 196 Discharge unit 198 Discharge roll 200 Built-in image Sensor 202 Illumination unit 204 CCD sensor 206 Imaging optical system 208 Imaging unit 212 Lamp 212A First lamp 212B Second lamp 214 First mirror 216 Second mirror 218 Third mirror 220 Lens 224 (224L, 224S, 224U) Section 226 Reference roll 210 Setting section 226 Reference roll 228 Detection reference plane 230 Retraction plane 231 Red reference plane 232 White reference plane 233 Green reference plane 234 Yellow reference plane 235 Blue Color reference surface 236 Composite inspection surface 237 Cyan color reference surface 239 Magenta color reference surface 250 Information collection unit 252 Analysis processing unit 254 Reception unit 256 Reference surface selection unit 258 Drive pulse signal output unit 260 Processing status monitoring unit 261 Positioning confirmation unit 262 Circuit Substrate 264 Selection reference plane reading instructing unit 268 Reading image information collecting unit 270 Difference data calculating unit 272 Standardized data calculating unit 274 Data storage unit 276 Data reading unit 278 Analysis unit 280 Analysis result determination unit 282 Notification information output unit 286 Window glass 350 Reading Signal processing unit 370 dimming circuit

Claims (8)

Reading means using a color reference surface having an achromatic color reference surface and a chromatic color reference surface ;
First detection means for detecting the presence of dust from the read information of the achromatic reference plane;
Second detection means for detecting the presence of dust from the read information of the chromatic color reference plane;
Third detection means for detecting the type of optical component to which dust has adhered, based on the detection results of the first detection means and the second detection means;
An image reading apparatus.   The third detecting means is a color having a complementary color relationship with the reading information of the relatively low reflectivity portion on the achromatic color reference surface and the color of the chromatic color reference surface in the color-separated reading information of the chromatic color reference surface. 2. The image reading apparatus according to claim 1, wherein the position of the dust having a relatively high reflectance and the type of the attached optical component are detected as compared with the component reading information.   The third detection means includes color information that is not complementary to the color information of the chromatic color reference surface in the read information of the relatively high reflectance portion of the color reference surface and the color separated color information of the color reference surface. 3. The image reading apparatus according to claim 1, wherein the position of the dust having a relatively low reflectivity and the type of the attached optical component are detected as compared with the read information.   In the detection results of the first detection unit and the second detection unit, the third detection unit may detect that dust is present in an optical component located on the optical path other than the color reference plane when dust is present at the same position. The position is detected by determination, and when dust is present at a different position, the position is detected by determining that dust is present on at least one of the achromatic color reference surface and the chromatic color reference surface. The image reading apparatus described. 5. The apparatus according to claim 1 , further comprising: a first notification unit that notifies the user that the presence of dust is detected when the presence of dust is detected by the third detection unit. Image reading apparatus. 2. The apparatus according to claim 1 , further comprising second informing means for informing the user of the cleaning location, the size of the dust, and the type of black / white dust when the third detecting means detects the presence of dust. The image reading apparatus according to any one of 5 to 5 . 7. The display device according to claim 1 , further comprising display means for displaying a degree of overlap between the test chart printed for color correction and the detected dust when the presence of dust is detected by the third detection means. The image reading apparatus according to claim 1. An image forming apparatus to which the image reading apparatus according to claim 1 is applied for generating a correction coefficient for calibration at the time of image formation in an image forming unit.

Images