JP2014235285A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus configured to reduce the number of recording sheets to be used for removing toner contamination, by printing multiple blank sheets on the same surface.SOLUTION: A control apparatus 10 includes: a contamination degree calculation unit 105 which calculates a contamination degree on the basis of image data from a solid-state image sensor 62 of an image inspection apparatus 6; a contamination degree change calculation unit 106 which calculates the amount of change in contamination degree of a recording sheet P1; and a conveyance control unit 107 for issuing an instruction for discharging or conveying the recording sheet P2. In executing a cleaning function, the conveyance control unit 107 controls conveyance state of the recording sheet for blank sheet printing, on the basis of calculation results of the contamination degree calculation unit 105 and the contamination degree change calculation unit 106.

Description

  The present invention relates to an image forming apparatus for forming an image on recording paper by an electrophotographic method, and more particularly to an image forming apparatus having a cleaning function for removing dirt on a recording paper conveyance path.

  The electrophotographic image forming apparatus forms an image on the paper surface by fixing the toner image after transferring the toner image onto the recording paper in the printing operation. At this time, on the downstream side of the image forming apparatus that transfers the toner image to the recording paper, the residual toner that has not been transferred to the recording paper floats and adheres to the conveyance path for conveying the recording paper. Further, when a paper jam or the like occurs in the fixing device that fixes the toner image on the recording paper, the toner that is not fixed on the recording paper may become dirty and adhere to the conveyance path around the fixing device. When the recording paper is passed through the conveyance path having the toner contamination, noise based on the toner contamination is generated on the image formed on the recording paper, and the image quality is deteriorated.

  In order to suppress such a deterioration in image quality due to toner contamination on the conveyance path, an image forming apparatus capable of executing a cleaning function of passing the conveyance path through the recording sheet in a state where the toner transfer operation is stopped has been proposed. (See Patent Document 1). The image forming apparatus disclosed in Patent Document 1 can remove toner stains on the conveyance path with the recording paper that has passed through the conveyance path by executing the cleaning function. In addition, the image forming apparatus disclosed in Patent Document 1 has an inspection apparatus that inspects the quality of an image formed on a recording sheet on which an image has been formed. Then, the inspection apparatus inspects the image on the paper surface with respect to the recording paper on which the printing operation by the cleaning function (blank paper printing) has been performed, thereby determining the presence or absence of toner contamination on the conveyance path.

JP 2006-162855 A

  The image forming apparatus disclosed in Patent Document 1 determines whether or not blank paper printing is possible when the cleaning function is executed based on the inspection result of the inspection apparatus. However, in the image forming apparatus of Patent Document 1, blank paper printing for executing the cleaning function is performed for each recording sheet. For this reason, the density and range of toner stains adhering to the recording paper decreases every time the number of times of blank paper printing is repeated, but cannot be used for normal printing, and the recording paper used for blank paper printing is discarded. Therefore, in the image forming apparatus of Patent Document 1, since the same number of recording sheets as the number of times of blank printing performed at the time of executing the cleaning function is used, the recording sheets are wasted.

  In view of such a problem, an object of the present invention is to provide an image forming apparatus capable of reducing the number of recording sheets used for removing toner stains by enabling a plurality of blank sheet printings on the same surface. And

  In order to achieve the above object, an image forming apparatus of the present invention includes a transfer unit that transfers a toner image onto a recording sheet, a fixing unit that fixes the toner image transferred onto the recording sheet at the transfer unit, and the transfer unit. A main conveyance path for conveying the recording paper to the image forming section and the fixing section, a paper feeding section for feeding the recording paper to the main conveyance path, and an image passing through the transfer section and the fixing section by the main conveyance path. A paper discharge unit that discharges the formed recording paper to the outside of the apparatus, and an image having a cleaning function for removing dirt on the main conveyance path by white paper printing in which the transfer operation by the transfer unit is stopped In the forming apparatus, an image inspection unit that is disposed between the fixing unit and the paper discharge unit on the main conveyance path and inspects an image formed on the recording paper, and based on an inspection result by the image inspection unit , When the blank printing is executed Based on the degree of contamination of the recording paper obtained by the contamination degree calculating unit, the degree of contamination transferred to the paper is calculated. A conveyance control unit that determines whether or not to pass again through the conveyance path, and when the printing function is executed and the blank sheet printing is repeated a plurality of times, the degree of contamination of the recording sheet exceeds the recording sheet reuse threshold. Up to this point, it is characterized in that the conveyance control unit determines that the blank printing with the same recording paper is repeated.

  In this image forming apparatus, when the blank printing with the same recording paper is repeated, the smearing degree of the recording paper calculated by the smearing degree calculation unit, and the smearing degree of the recording paper calculated by the previous blank paper printing, Thus, a stain degree change amount calculating unit for calculating the stain degree change amount of the recording paper is further provided, and the conveyance control unit is configured to determine whether the stain degree change amount of the recording paper obtained by the stain degree change amount calculating unit is obtained. It may be determined that the execution of the cleaning function is stopped when the cleaning execution threshold is exceeded.

  In each of the image forming apparatuses described above, the conveyance control unit is in a state where the amount of change in the degree of contamination of the recording paper in the continuous white paper printing does not decrease when the white paper is continuously printed during the execution of the cleaning function. Counting may be performed and it may be determined that an apparatus abnormality has occurred when the count value exceeds a predetermined value.

  In each of the image forming apparatuses described above, the blank printing is repeated a predetermined number of times after the start of the execution of the cleaning function, and the same recording is performed based on the degree of smearing of the recording paper obtained by the smear degree calculating unit in each blank paper printing. A timing prediction unit that predicts the number of times that blank paper printing can be repeated on paper and sets the number of reuse limits, and until the transport control unit reaches the number of reuse limits Alternatively, it may be determined that the blank printing with the same recording paper is repeated.

  At this time, the timing prediction unit sets the number of times of blank paper printing to be repeated thereafter as the number of cleaning completions based on the degree of contamination of the recording paper obtained in each blank paper printing repeated a predetermined number of times after the start of execution of the cleaning function. The transport control unit may stop the execution of the cleaning function when the blank sheet printing is performed for the number of cleaning completion times.

  Each of the above-described image forming apparatuses includes a circulation path for circulating the recording paper that has passed through the image inspection unit, and when the conveyance control unit determines that the blank printing with the same recording paper is repeated, the image The recording paper that has passed through the inspection apparatus may be circulated through the circulation path to the main conveyance path to execute blank paper printing on the recording paper.

  At this time, the circulation path may include a reversal conveyance path that reverses the surface of the recording paper, and performs blank paper printing on both sides of the recording paper during execution of the cleaning function.

  In the image forming apparatus described above, each time the blank sheet is printed, the recording sheet that has passed through the image inspection unit is discharged to the discharge unit, and the conveyance control unit prints the blank sheet using the same recording sheet. If it is determined that the process is to be repeated, the recording paper discharged to the paper discharge unit after white paper printing may be notified to the outside so as to be placed on the paper supply unit.

  Further, in each of the image forming apparatuses described above, when the conveyance control unit determines that the recording paper to be printed with a blank sheet is to be changed, the recording sheet printed with the blank sheet is discharged to the paper discharge unit and then another recording is performed. Paper may be fed out from the paper feeding unit to the main conveyance path to be printed on white paper.

  According to the present invention, blank paper printing can be repeated on the same recording paper during execution of the cleaning function, so that the consumption of recording paper used for the cleaning function can be reduced. Moreover, since both sides of the recording paper can be targeted for the blank printing of the cleaning function a plurality of times, the consumption of the recording paper can be further reduced. Furthermore, by providing a configuration capable of predicting the number of times of blank paper printing required for executing the cleaning function, it is possible to execute replenishment of recording paper for the number of times of blank paper or termination of the cleaning function based on the predicted number of times. Therefore, it is only necessary to operate the image inspecting unit only when performing blank paper printing necessary for predicting the number of times when executing the cleaning function, and the power consumption when executing the cleaning function can be reduced.

1 is a schematic configuration diagram showing an internal configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram illustrating a configuration of an image inspection apparatus in the image forming apparatus illustrated in FIG. 1. These are schematic block diagrams which show another structure of the image inspection apparatus in the image forming apparatus shown in FIG. FIG. 2 is a block diagram showing a part of a configuration of a control device in the image forming apparatus of FIG. 1. These are flowcharts which show the operation at the time of executing the cleaning function in the first embodiment. These are flowcharts which show the operation at the time of executing the cleaning function in the first embodiment. Indicates the relationship between the degree of smearing and the degree of smearing change due to white paper printing, where (a) shows the state of the recording paper during the first white paper printing, and (b) shows the second time. This shows the state of the recording paper when printing blank paper. These are the schematic block diagrams which show the internal structure of the image forming apparatus in the 2nd Embodiment of this invention. These are flowcharts which show the operation | movement at the time of the cleaning function execution in 2nd Embodiment. These are flowcharts which show the operation | movement at the time of the cleaning function execution in 2nd Embodiment. These are block diagrams which show a part of a structure of the control apparatus in the image forming apparatus of 3rd Embodiment. These are flowcharts which show the operation | movement at the time of the cleaning function execution in 3rd Embodiment. These are flowcharts which show the operation | movement at the time of the cleaning function execution in 3rd Embodiment. These are the schematic block diagrams which show the internal structure of the image forming apparatus in the 4th Embodiment of this invention. These are the flowcharts which show the operation | movement at the time of execution of the cleaning function in 4th Embodiment. These are the flowcharts which show the operation | movement at the time of execution of the cleaning function in 4th Embodiment.

<First Embodiment>
An image forming apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of the image forming apparatus according to the present exemplary embodiment. Note that an image forming apparatus in each of the following embodiments including the present embodiment may be an apparatus that includes both an image reading mechanism and an image inspection mechanism. For example, a copier, a printer or a multifunction peripheral having a copy function, and the like. It does not matter.

1. Configuration of Image Forming Apparatus The configuration of the image forming apparatus 1 will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing an internal configuration of the image forming apparatus 1.

  An image forming apparatus 1 shown in FIG. 1 stores an image reading apparatus 2 that reads an image from a document and a recording sheet P1 for printing an image, and feeds the recording sheet P1 into the image forming apparatus 1. The image forming apparatus 4 that transfers the toner image to the recording paper P1 based on the document image data obtained by reading by the image reading apparatus 2 and the image reading apparatus 2, and the toner image transferred to the recording paper P1 by the image forming apparatus 4 The fixing device 5 for fixing, the image inspection device 6 for inspecting the printing state of the recording paper P1 on which the toner image is fixed by the fixing device 5, and the recording paper P1 after the printing inspected by the image inspection device 6 And an operation unit 8 composed of a touch panel for displaying an operation instruction button group and a device status display and simultaneously accepting an operation from a user.

  The image reading apparatus 2 forms an image on the solid-state imaging device 22, a light source 21 that irradiates light on the document, a solid-state image sensor 22 that receives reflected light from the document and converts it into an electrical signal, and the reflected light from the document. The imaging lens 23, the original glass plate 24 on which the original is placed, the reflecting mirror 25 that reflects the light from the light source 21 and irradiates the surface of the original, and the reflected light from the original is guided to the imaging lens 23. The reflectors 26A to 26C and a reference plate 27 for generating a correction value for shading correction are provided.

  The imaging lens 23 and the solid-state imaging device 22 each have a plurality of elements in a direction (corresponding to “main scanning direction”) perpendicular to the document reading direction (corresponding to “sub-scanning direction”). It consists of a group of elements arranged for each. Further, in the solid-state imaging device 22, since a primary color or complementary color filter is installed on the light receiving surface of each pixel, the light of the light transmitted through the color filter is received by each pixel device, so Read the image as a color image. Further, the light source 21 and the reflecting mirrors 25 and 26A are provided in the first slider portion 211, and the reflecting mirrors 26B and 26C are provided in the second slider portion 212. The first and second slider parts 211 and 212 are simultaneously moved in the sub-scanning direction by a moving mechanism (not shown) such as a rail and a motor, so that the sub-scanning direction of the original placed on the surface of the original glass plate 24 is increased. Reading to is performed.

  In the image reading apparatus 2 configured as described above, when reading an image of a document, the document is placed on a document glass plate 24 of a document placing table, or an automatic document feeder (ADF: Auto Document Feeder). ) To the original glass plate 24. At this time, when the irradiation light from the light source 21 and the reflected light from the reflecting mirror 25 are irradiated to the reading position of the document, the reflected light from the document with respect to this irradiation light is incident on the reflecting mirror 26A. Then, the reflected light from the reflecting mirror 26A is sequentially reflected by the reflecting mirrors 26B and 26C, guided to the imaging lens 23, and the reflected light from the original is transmitted through the imaging lens 23, and the solid-state imaging device 22 takes an image. The image is formed on the area. The solid-state imaging device 22 outputs an electric signal corresponding to the amount of received light for each line at a constant interval in accordance with the reading width along the sub-scanning direction, so that a two-dimensional original image based on the image on the original is obtained. Data is generated.

  Further, the image reading device 2 moves the first slider portion 211 and the second slider portion 212 to move the first slider portion 211 to a position directly below the reference plate 27 before performing the image reading operation of the document. The reference plate 27 is read. Thereby, the correction value for carrying out the shading correction | amendment of the output value of the electric signal output from the solid-state image sensor 22 to a main scanning direction is generable. Therefore, by performing shading correction based on this correction value for the electrical signal output from the solid-state image pickup device 22, variation in the amount of light in the main scanning direction by the light source 21 can be suppressed in the generated document image data.

  As shown in FIG. 1, the paper feed device 3 includes a paper feed cassette 31 that stores a recording paper P1 on which an image is printed, a paper feed roller pair 32 that takes out the recording paper P1 stored in the paper feed cassette 31, Is provided. Further, on the downstream side of the paper feeding device 3, a registration roller pair 33 is provided for transporting the recording paper P 1 fed from the paper feeding cassette 31 to the recording paper transporting path by the paper feeding roller pair 32 to the image forming device 4. ing. The sheet feeding device 3 configured in this manner takes out the recording sheets P1 stored in the sheet feeding cassette 31 one by one by feeding the pair of sheet feeding rollers 32, and supplies them to the recording sheet conveyance path. Then, the recording paper P1 discharged from the paper feeding cassette 31 is conveyed toward the image forming device 4 by a conveying roller pair 91 installed on the downstream side of the paper feeding device 3 along the conveying direction of the recording paper P1. The Thereafter, the registration roller pair 33 controls the conveyance timing to the image forming device 4 so that the recording paper is conveyed in accordance with the transfer timing in the image forming device 4.

  The image forming device 4 is carried on each of the photosensitive drums 41 to 44 on which electrostatic latent images of each color of Y (Yellow) M (Magenta) C (Cyan) K (Black) are formed, and the photosensitive drums 41 to 44, respectively. An intermediate transfer portion 45 to which toner of each color of YMCK is transferred, and a secondary transfer roller 46 to transfer the toner transferred to the intermediate transfer portion 45 to the recording paper P1. At this time, although not shown, each of the photosensitive drums 41 to 44 is provided with a charger for charging the photosensitive drums 41 to 44 by corona discharge or the like, and a laser beam or the like to the charged photosensitive drums 41 to 44. An exposure device that forms an electrostatic latent image by irradiation, a developing device that charges the YMCK toners by stirring and adheres them to the photosensitive drums 41 to 44, and the photosensitive drums 41 to 44 after being transferred to the intermediate transfer unit 45. And a cleaning member for removing the toner remaining on the toner.

  The intermediate transfer unit 45 also includes an intermediate transfer belt 451 to which toner of each color of YMCK is transferred from the photosensitive drums 41 to 44, a driving roller 452 and a driven roller 453 for rotating the intermediate transfer belt 451, and photosensitive drums 41 to 44, respectively. Are provided with primary transfer rollers 454 to 457 installed at positions facing each other with the intermediate transfer belt 451 interposed therebetween. Further, the intermediate transfer unit 45 includes a cleaning member (not shown) in order to remove toner remaining on the intermediate transfer belt 451 without being transferred onto the recording paper P1 from the surface of the intermediate transfer belt 451. The secondary transfer roller 46 is installed at a position facing the driving roller 452 with the intermediate transfer belt 451 interposed therebetween.

  In the image forming apparatus 4 configured as described above, the photosensitive drums 41 to 44 have electrostatic latent images of each color of YMCK on the surfaces of the photosensitive drums 41 to 44 based on the document image data acquired by the image reading mechanism 2. Is formed, the charged YMCK color toners are carried on the electrostatic latent images of the photosensitive drums 41 to 44, respectively. In the intermediate transfer unit 45, the intermediate transfer belt 451 is rotated by the driving roller 452, and the toner images of each color of YMCK carried on the photosensitive drums 41 to 44 are primary transfer rollers 454 to 457 to which a predetermined potential is applied. Is transferred to the intermediate transfer belt 451 by the electrostatic force.

  At this time, the intermediate transfer belt 451 sequentially transfers the toner images of the respective colors from the photosensitive drums 41 to 44 in the order of YMCK by the portions where the toner images to be transferred to the recording paper P1 are sequentially contacted with the photosensitive drums 41 to 44. Is done. Further, YMCK toner images on the surfaces of the photosensitive drums 41 to 44 are formed in the order of the photosensitive drums 41 to 44 in accordance with the timing of transferring the toner to the intermediate transfer belt 451.

  The toner image formed by transferring the YMCK color toners onto the surface of the intermediate transfer belt 451 moves to a position where the surface of the intermediate transfer belt 451 on which the toner image is formed is opposed to the secondary transfer roller 46. Then, the toner image is transferred to the recording paper P1 sandwiched between the intermediate transfer belt 451 and the secondary transfer roller 46. The transfer of the toner image onto the recording paper P1 is realized by the charged toner of each color being attracted to the secondary transfer roller 46 by the voltage applied to the secondary transfer roller 46.

  The fixing device 5 includes a heating roller 51 including a halogen lamp that heats the toner on the recording paper P1, and a pressure roller 52 that presses the recording paper P1 while sandwiching the heating roller 51 and the recording paper P1. The recording paper P1 on which the toner image is transferred by the image forming device 4 is conveyed. The recording paper P1 onto which the toner image has been transferred passes between the heating roller 51 and the pressure roller 52, thereby being heated by the heating roller 51 and pressurized by the heating roller 51 and the pressure roller 52. . As a result, the transferred toner image is fixed on the recording paper P1, and an image based on the original image data is printed on the recording paper P1. The heating roller 51 may be one in which the surface of the heating roller 51 is heated by generating an eddy current on the surface by electromagnetic induction.

  The paper discharge device 7 is provided outside the image forming apparatus 1 and discharged by the paper discharge roller 71 for discharging the recording paper P1 that has passed through the image inspection device 6 to the outside of the image forming device 1. A paper discharge tray 72 for receiving the printed recording paper P1. In the paper discharge device 7 configured as described above, the recording paper P1 on which the toner image is fixed on the recording surface by the fixing device 5 is guided from the image inspection device 6 by driving the paper discharge roller pair 71. Then, the paper is discharged to a paper discharge tray 72 outside the image forming apparatus 1.

  As described above, the image forming apparatus 1 including the devices 2 to 8 branches from the main conveyance path 80 (solid line portion in FIG. 1) for forming an image on the recording paper and the main conveyance path 80 and forms an image. And a reversal conveyance path 81 (a chain line portion in FIG. 1) for reversing the recorded paper and circulating it to the main conveyance path 80. The main transport path 80 is a transport path until the recording paper fed from the paper feed cassette 31 of the paper feed device 3 is discharged to the paper discharge tray 72 of the paper discharge device 7. The reverse conveyance path 81 is a conveyance path that branches on the upstream side of the paper discharge roller pair 71 and joins the upstream side of the registration roller pair 33 with respect to the main conveyance path 80, and the reverse roller pair 85 is arranged along the path. Have. By the normal reversing operation of the reversing roller pair 85 in the reversing conveyance path 81, the recording paper conveyed from the main conveying path 80 is reversed and sent again to the main conveying path 80.

  On the main conveyance path 80, along the recording paper conveyance direction, a transfer roller nip portion formed by a paper feed roller pair 32, a conveyance roller pair 91, a registration roller pair 33, an intermediate transfer belt 451 and a secondary transfer roller 46, and a heating roller 51 The fixing nip portion by the pressure roller 52, the transport roller pair 92, the image inspection apparatus 6, the transport roller pair 93, and the paper discharge roller pair 71 are arranged in order. For the reverse conveyance path 81, the conveyance roller pair 94 and the reverse roller pair 85 are arranged on the conveyance path 81 a branched from the downstream side of the conveyance roller pair 93. A transport roller pair 95 is arranged on the transport path 81b branched on the upstream side of the reverse roller pair 85 of the transport path 81a, and the transport path 81b joins the main transport path 80 on the upstream side of the registration roller pair 33. To do.

  In such a configuration, when single-side printing is instructed to the image forming apparatus 1, the pair of paper feed rollers 32 feeds the recording paper P <b> 1 from the paper feed tray 31 to the main transport path 80 in the paper feed device 3. Then, the recording paper P <b> 1 is conveyed toward the image forming device 4 by the conveyance roller pair 91. The recording paper P 1 is conveyed to the image forming device 4 by the registration roller pair 33 in accordance with the image forming timing in the image forming device 4. As a result, the toner image formed on the intermediate transfer belt 451 of the image forming device 4 is transferred to the recording paper P1 by the electrostatic force of the secondary transfer roller 46.

  The recording paper P1 that has passed through the image forming device 4 passes through the fixing device 5, whereby the transferred toner image is melted and fixed on the paper surface by heating and pressing of the heating roller 51 and the pressure roller 52. The recording paper P <b> 1 formed in this way passes through the image inspection apparatus 6 disposed on the main transport path 80 by the rotational drive of the transport roller pair 92, 93, and as will be described later, the recording paper P <b> 1. The quality of the image formed on P1 is inspected. Since the transport roller pair 93 together with the transport guide (not shown) guides the recording paper P1 to the paper discharge roller pair 71 side, the recording paper P1 is transported on the main transport path 80 and then the paper discharge roller pair 71. The paper is discharged to a paper discharge tray 72 outside the image forming apparatus 1 by rotation driving.

  On the other hand, when double-sided printing is instructed to the image forming apparatus 1, as in the case of single-sided printing, the recording paper P 1 fed from the paper feed tray 31 to the main transport path 80 by the paper feed roller pair 32 is It is conveyed toward the image forming device 4 by the conveyance roller pair 91 and the registration roller pair 33. After the recording paper P1 passes through the image forming device 4 and the fixing device 5 on the main conveyance path 80, an image is formed on one side thereof, and then the image inspection apparatus is driven by the rotation of the conveyance roller pairs 92 and 93. Passing through 6, the quality of the formed image is inspected.

  When the recording paper P1 image-formed on one side in this way passes through the image inspection apparatus 6, the conveyance roller pair 93 together with a conveyance guide (not shown) guides the recording paper P1 to the reverse conveyance path 81. Accordingly, the recording paper P1 having an image formed on one side is guided to the reverse roller pair 85 by the transport roller pair 94 in the transport path 81a of the reverse transport path 81. The reverse roller pair 85 rotates the recording paper P1 in the same direction as the transport direction on the transport path 81a by rotating in the same direction as the transport roller pair 94, and then reverses the rotation direction. At the same time as the rotation direction of the reverse roller pair 85 is reversed, the recording paper P1 is guided to the conveyance path 81b of the reverse conveyance path 81 by a guide (not shown).

  As a result, the recording paper P1 is turned upside down and transported through the transport path 81b, and the recording paper P1 is guided to the main transport path 80 by the transport roller pair 95 and a guide (not shown). Thereafter, the recording paper P <b> 1 conveyed from the reverse conveyance path 81 to the main conveyance path 80 is conveyed toward the image forming device 4 by the registration roller pair 33. At this time, the recording paper P1 contacts the intermediate transfer belt 451 and the heating roller 51 with the opposite side surface (back surface) of the surface (front surface) on which the image has already been formed, so that the recording paper P1 moves the image forming device 4 and the fixing device 5 together. By passing, an image is also formed on the back surface.

  The recording paper P1 formed with images on both sides thereof passes through the image inspection device 6 by the rotational driving of the conveyance roller pairs 92 and 93, so that the quality of the image formed on the back surface of the recording paper P1 is described later. Is inspected. Since the conveyance roller pair 93 guides the recording paper P1 to the paper discharge roller pair 71 side together with a conveyance guide (not shown), the double-sided recording paper P1 is driven by the rotation of the paper discharge roller pair 71 to form an image forming apparatus. 1 The paper is discharged to an external paper discharge tray 72.

2. Configuration of Image Inspection Apparatus As shown in FIG. 2, the image inspection apparatus 6 receives a light source 61 such as a laser diode that irradiates light onto a recording paper P1 on which an image is printed, and reflected light from the recording paper P1. In the solid-state image sensor 62 that converts to an electrical signal, the imaging lens 63 that forms an image of the reflected light from the recording paper P1 on the solid-state image sensor 62, and the sub-scanning direction (corresponding to the transport direction in the main transport path 80). A glass plate 64 with which the image recording surface of the moving recording paper P1 comes into contact, a reflecting mirror 65 that reflects light from the light source 61 and irradiates the recording paper surface, and guides reflected light from the recording paper to the imaging lens 63. Reflecting mirrors 66A to 66C, and a reference plate 67 for generating a correction value for shading correction.

  At this time, each of the solid-state imaging device 62 and the imaging lens 63 is configured by an element group in which a plurality of elements are arranged for each pixel in the main scanning direction. The solid-state image sensor 62 is provided with a primary color or complementary color filter on the light receiving surface of each pixel, and reads an image on a recording sheet as a color image. The image inspection apparatus 6 is constituted by a housing whose surface on the main conveyance path 80 side is covered with a glass plate 64, and includes a light source 61, a solid-state imaging device 62, an imaging lens 63, and reflecting mirrors 65 and 66A. To 66C are fixed inside the casing, and a reference plate 67 is fixed at a position directly below the reflecting mirror 66A via the main conveyance path 80.

  When the recording paper P1 is transported through the main transport path 80 to the image inspection apparatus 6 configured as described above, the image on the recording paper P1 is read line by line along the sub-scanning direction. That is, when the irradiation light from the light source 61 and the reflection light from the reflecting mirror 65 are irradiated to the reading position of the recording paper P1, the reflected light from the recording paper P1 with respect to this irradiation light is reflected by the reflecting mirrors 66A to 66C. Are sequentially reflected. Then, the reflected light from the recording paper P <b> 1 reflected by the reflecting mirror 66 </ b> C passes through the imaging lens 63 and forms an image on the imaging region of the solid-state imaging device 62. The solid-state imaging device 62 outputs an electric signal corresponding to the amount of received light for each line at a constant interval according to the reading width along the sub-scanning direction, so that a two-dimensional image based on the image on the recording paper P1 is obtained. Recording paper image data is generated.

  Further, the image inspection apparatus 6 performs a reading operation of the reference plate 67 disposed at a position opposed to the main conveyance path 80 before performing the image reading operation of the recording paper P1. Thereby, the correction value for carrying out the shading correction | amendment of the output value of the electrical signal output from the solid-state image sensor 62 to a main scanning direction is generable. Accordingly, by performing shading correction based on this correction value for the electrical signal output from the solid-state image sensor 62, variation in the amount of light in the main scanning direction by the light source 61 can be suppressed in the generated recording paper image data. .

  The image inspection device 6 is similar to the image reading device 2 for the recording paper on which the toner image transferred by the image forming device 4 is fixed by the fixing device 5 during a normal printing operation on the recording paper P1. An image reading operation is performed. That is, the image inspection apparatus 6 operates the light source 61 and the solid-state image sensor 62 to read an image on the recording paper P1 passing through the main conveyance path 80, and the read image is the control apparatus 10 (FIG. 4) described later. Send it to Then, the control device 10 forms the image acquired on the recording paper P1 by comparing the image acquired from the image inspection device 6 with an image read from the document by the image reading device 2 or an image given from an external network. The quality of the printed image is inspected to determine whether the printing state is good or bad.

  The configuration of the image inspection apparatus 6 is not limited to the configuration of FIG. 2 described above. For example, only the reflecting mirror 66 is disposed to form an optical path for guiding the reflected light from the recording paper to the solid-state imaging device 62. However, the configuration may be simplified as in the configuration shown in FIG.

3. Cleaning Function The image forming apparatus 1 including the image inspection apparatus 6 having the above configuration performs a main transport by executing a cleaning function for passing the recording paper P1 in a state where the toner image forming operation in the image forming apparatus 4 is stopped. Dirt due to toner or the like in the path 80 can be removed. The configuration and operation for executing this cleaning function will be described below with reference to the drawings. FIG. 4 is a block diagram showing a configuration for executing the cleaning function in the control device of the image forming apparatus 1, and FIGS. 5 and 6 are flowcharts showing the control operation when the cleaning function is executed. In the following description, the execution operation of the cleaning function is simply “blank printing” because printing is performed without image formation by the image forming device 4.

  As shown in FIG. 4, the control device 10 temporarily stores a CPU (Central Processing Unit) 101 that executes various arithmetic processes and controls, a ROM (Read Only Memory) 102 that stores a control program, and arithmetic data. A RAM (Random Access Memory) 103 for storing, a storage unit 104 such as an EEPROM (Electrically Erasable Programmable Read-Only Memory) for storing data used for reference during blank printing, and a solid-state image sensor 62 of the image inspection apparatus 6 A stain level calculation unit 105 that calculates a stain level based on image data from the image data, a stain level change amount calculation unit 106 that calculates a change level of the stain level of the recording paper P1, and an instruction to discharge or convey the recording paper P2. Between the blocks in the control apparatus 10, the input / output interface 108 for transmitting and receiving signals to and from the apparatuses 2 to 8 in the image forming apparatus 1 It includes a bus 109 for transmitting and receiving signals in order to establish communications, the.

  When the control device 10 is configured in this way, the storage unit 104 stores the contamination level and the contamination level change amount calculated by the contamination level calculation unit 105 and the contamination level change amount calculation unit 106, and the contamination level of the recording paper P1. The high smudge degree count value based on the count value for high white paper printing is stored corresponding to each of the front surface (first surface) and the back surface (second surface) of the recording paper P1 used for white paper printing. The storage unit 104 also has a cleaning execution threshold value (first threshold value) serving as a reference value for determining whether or not blank printing is complete, and a reference value for determining whether or not the recording paper P1 can be reused for blank printing. The recording paper reuse threshold value (second threshold value) is stored.

  When the control device 10 executes the control operation according to the operation flow shown in FIGS. 5 and 6, the image forming apparatus 1 executes the cleaning function by printing on the blank paper using the recording paper P1. At this time, for example, when the control device 10 receives a notification of the completion of the repair work for the image forming apparatus 1 through the input / output interface 108 by a user operation or the like in the operation unit 8, the control operation for blank paper printing is started. (STEP 1).

  Note that, as an example of the trigger for executing the blank page printing, the trigger based on the completion of the repair work on the image forming apparatus 1 has been described as an example. However, the execution of the blank page printing itself may be instructed by the operation of the operation unit 8. In addition, the operation of notifying the image forming apparatus 1 of the completion of the repair work is not limited to accepting the operation to the operation unit 8. For example, the sensor senses that the failure occurrence location of the image forming apparatus 1 has been repaired. The control device 10 may be able to confirm the completion of the repair work based on the signal from the sensor.

  When the control device 10 starts a control operation for printing blank paper, first, the high stain count value, the stain detection value, and the stain change amount stored in the storage unit 104 are reset to initial values. (STEP2). The initial value of the smear level detection value is determined for each paper type of the recording paper P1 before the printing operation on the recording paper P1 is performed, for example, when the image forming apparatus 1 is shipped or installed. Blank printing is executed in advance, and the value calculated by the smear level calculation unit 105 is stored in the recording unit 104 as an initial value. For example, when the user stores the recording paper P1 in the paper feeding cassette 31 of the paper feeding device 3, the operation unit 8 is operated to notify the control device 10 of the paper type of the recording paper P1. The initial value of the contamination level detection value corresponding to the recording paper P1 accommodated in the paper cassette 31 may be selected.

  In STEP 2, the CPU 101 resets each value stored in the storage unit 104 to an initial value, and then feeds the recording paper P 1 from the paper feed cassette 31 by the paper feed device 3 to the main transport path 80. A paper feed control signal is generated by 107 (STEP 3). This paper feed control signal is given to the paper feed roller pair 32 through the input / output interface 108, whereby the paper feed roller pair 32 is driven to rotate, and the recording paper P1 of the paper feed cassette 31 is fed out to the main transport path 80. It is.

  Thereafter, the control device 10 generates a control signal for executing blank printing of the recording paper P1 fed out from the paper feed cassette 31, and outputs it through the input / output interface 108 (STEP 4). At this time, the conveyance control unit 107 rotationally drives the conveyance roller pair 91 to 93, the registration roller pair 33, the driving roller 452 in the intermediate transfer unit 45, and the heating roller 51 or the pressure roller 52 in the fixing device 5 at a predetermined timing. Thus, a transport control signal is generated and output from the input / output interface 108. Simultaneously with the output of the transport control signal, the CPU 101 generates a heating control signal for executing the heating operation of the heating roller 51 in the fixing device 5 and outputs it from the input / output interface 108.

  Based on each control signal from the control device 10, each pair of rollers in the main transport path 80 is driven, whereby the recording paper P 1 is transported on the main transport path 80, and the image forming device 4 and the fixing device 5. Through in order. At this time, in the image forming device 4, the driving of the charger and the exposure unit provided for the photosensitive drums 41 to 44 is stopped, and the voltage application to the primary transfer rollers 454 to 457 is also stopped. . Accordingly, the intermediate transfer belt 451 is in a state where no toner is transferred from the photosensitive drums 41 to 44.

  Therefore, when the recording paper P1 passes through the image forming device 4 and reaches the fixing device 5, the toner stain on the main conveyance path 80 adheres to the recording paper P1. Then, when the recording paper P1 to which the toner stain has adhered passes through the fixing device 5, the toner stain adhered to the recording paper P1 on the surface of the recording paper P1 due to heating and pressurization by the heating roller 51 and the pressure roller 52. To fix. The recording paper P1 that has passed through the fixing device 5 is transported to the image inspection device 6 on the main transport path 80 by the rotational drive of the transport roller pair 92.

  In this way, when the recording paper P1 reaches the image inspection apparatus 6, the CPU 101 generates an inspection control signal for driving the image inspection apparatus 6 and supplies it to the image inspection apparatus 6 from the input / output interface 108. 6 is executed (STEP 5). At this time, the image inspection apparatus 6 causes the light source 61 to emit light and simultaneously performs the imaging operation by the solid-state imaging device 62 at predetermined timings, thereby acquiring image data from the recording paper P1 after blank printing, and the control apparatus 10 to send. As a result, the image inspection device 6 functions as a contamination level detection device, and the control device 10 receives the image data obtained from the recording paper P1 at the input / output interface 108 as a contamination level detection signal.

  When the control device 10 receives the smear level detection signal (image data) from the image inspection device 6 by the input / output interface 108, the control device 10 confirms whether the blank paper printing on the recording paper P1 is the printing on the front surface or the back surface. (STEP 6). Note that a printing status flag for indicating the printing status is stored in the storage unit 104 as to whether or not the printing on the front side or the back side of the recording paper P1 is blank. The printing status flag stored in the storage unit 104 is reversed every time the sheet passes through the reverse conveyance path 81.

  When printing on the surface of the recording paper P1 (hereinafter referred to as “front surface printing”) (Yes in STEP 6), the CPU 101 determines the degree of smearing, the degree of smearing change, and the high smearing count value for the front surface printing. (Surface printing parameter) is read from the storage unit 104 (STEP 7). On the other hand, in the case of printing on the back side of the recording paper P1 (hereinafter referred to as “back side printing”) (NO in STEP 6), the CPU 101 determines the degree of smearing, the degree of smearing change, and the high smearing degree count value for backside printing. (Parameter for back side printing) is read from the storage unit 104 (STEP 8). The stain degree read in STEP 7 or STEP 8 is given to the stain degree change amount calculation unit 106, and the high stain degree count value and the stain degree change amount are given to the conveyance control unit 107.

  In the control device 10, the contamination level detection signal received by the input / output interface 108 is given to the contamination level calculation unit 105, and the contamination level calculation unit 105 performs image analysis on the image data based on the contamination level detection signal, thereby recording. The degree of contamination based on the amount of toner attached to the paper P1 is calculated (STEP 9). At this time, the stain level calculation unit 105 counts the number of pixels in the area (dirt area) where the toner is attached on the recording paper P1, and acquires the area of the area. Thereafter, the stain calculation unit 105 calculates the concealment rate on the recording paper P1 based on the ratio of the stain region to one sheet of the recording paper P1, and sets the concealment rate as the degree of contamination.

  When the contamination level calculation unit 105 calculates the contamination level, the calculated contamination level is given to the contamination level change amount calculation unit 106, so that the contamination level change amount calculation unit 106 has already been read from the storage unit 104. The amount of change in the contamination level is calculated based on the difference from the contamination level (STEP 10). At this time, the contamination level change amount calculation unit 106 temporarily stores the contamination level read from the storage unit 105 in STEP 7 or STEP 8 as the previous contamination level. Then, the stain level change amount calculation unit 106 receives the stain level newly calculated by the stain level calculation unit 105 and subtracts the previous stain level from the calculated stain level to calculate the stain level change amount. . That is, the stain level change amount corresponds to the level of stain due to one blank paper printing.

  After that, the conveyance control unit 107 first receives the contamination degree change amount calculated by the contamination degree change amount calculation unit 106, and then the cleaning execution threshold (first value) stored in the recording unit 104 for the contamination degree change amount. (STEP 11). At this time, if the stain level change amount is equal to or less than the first threshold (YES in STEP 11), the conveyance control unit 107 determines that the toner contamination in the main conveyance path 80 has been sufficiently removed, and the discharge roller pair 71. Is generated and output from the input / output interface 108 (STEP 12). Thus, when the recording paper P1 after inspection in the image inspection apparatus 6 is transported by the transport roller pair 93, the recording paper P1 is discharged to the paper discharge tray 72 by the rotational drive of the paper discharge roller pair 71, and the cleaning function End execution.

  On the other hand, when the contamination degree change amount is larger than the first threshold (No in STEP 11), the conveyance control unit 107 receives the contamination degree change amount obtained by the contamination degree change amount calculation unit 106 and has already read out from the storage unit 104. Compared with the previous change in the degree of contamination (STEP 13). At this time, the conveyance control unit 107 temporarily stores the contamination degree change amount read from the storage unit 105 in STEP 7 or STEP 8 as the previous contamination degree change amount. Then, the conveyance control unit 107 receives the contamination degree change amount newly calculated by the contamination degree change amount calculation unit 106, and compares the calculated contamination degree change amount with the previous contamination degree change amount.

  When the conveyance control unit 107 confirms that the calculated stain level change amount is equal to or greater than the previous stain level change amount (Yes in STEP 13), the toner stain amount in the main transport path 80 is large and the stain is sufficiently removed. It is determined that it is not, and the high contamination degree count value is counted once (STEP 14). Then, the conveyance control unit 107 checks whether or not the high contamination count value counted in STEP 14 has reached a predetermined number (STEP 15). That is, in STEP 15, the conveyance control unit 107 confirms the number of times of blank paper printing in which the recording paper P <b> 1 is determined to have a high degree of contamination based on the high contamination degree count value, for example, an apparatus abnormality such as toner leakage. Whether or not has occurred is determined.

  At this time, when the conveyance control unit 107 confirms that the high stain count value has reached the predetermined number of times (YES in STEP 15), it is determined that an apparatus abnormality has occurred, and the recording paper P1 is to be discharged. A paper discharge control signal similar to STEP 12 is generated and output from the input / output interface 108 (STEP 16). As a result, the recording paper P <b> 1 after the inspection in the image inspection apparatus 6 is discharged onto the discharge tray 72 by the rotation driving of the discharge roller pair 71. After that, the CPU 101 generates an external notification signal for notifying the outside of the device abnormality based on the determination result of the occurrence of the device abnormality by the transport control unit 107 and transmits it to the operation unit 8 through the input / output interface 108 (STEP 17). . Accordingly, the display unit of the operation unit 8 displays a display indicating that the apparatus has failed such that it is impossible to remove dirt by the cleaning function, and the execution of the cleaning function is terminated.

  On the other hand, when the calculated contamination degree change amount is smaller than the previous contamination degree change amount (NO in STEP 13), or when the high contamination degree count value has not reached the predetermined number of times (NO in STEP 15), the conveyance control unit 107 compares the stain level calculated by the stain level calculation unit 105 with the recording paper reuse threshold (second threshold) (STEP 18). At this time, if the stain level is lower than the second threshold (YES in STEP 18), the conveyance control unit 107 determines that the recording paper P1 for which blank printing has been completed can be reused, and the stain level calculation unit 105 and the stain level change amount calculation. The degree of contamination and the amount of change in the degree of contamination calculated by each unit 106 are stored in the storage unit 104 (STEP 19).

  Then, the conveyance control unit 107 generates a reversal control signal to circulate the recording paper P1 through the reversal conveyance path 81, and the reversal roller pair 85 and the conveyance roller pairs 94 and 95 of the reversal conveyance path 81 from the input / output interface 108. (STEP 20). As a result, the recording paper P1 that has passed through the image inspection apparatus 6 by the transport roller pair 93 is guided to the reverse transport path 81 by a guide (not shown). Thereafter, the recording paper P1 is reversed by rotating the reversing roller pair 85 after the recording paper P1 is moved along the conveying path 81a by the rotational driving of the conveying roller pair 94 and the reversing roller pair 85. When the conveyance roller pair 95 is rotationally driven together with the reversing roller pair 85, the recording paper P1 moves along the conveyance path 81b and is guided to the registration roller pair 33 in the main conveyance path 80.

  Further, in the control device 10, after the reverse control signal is output from the transport control unit 107, the printing status flag in the storage unit 104 is inverted and stored (STEP 21). That is, when a printing status flag indicating front side printing (back side printing) is stored in the storage unit 104, switching to back side printing (front side printing) is performed by the reverse control of STEP 20, so the flag is inverted at STEP 21 and back side printing ( A printing status flag indicating “front side printing” is stored in the storage unit 104. Thereafter, the process proceeds to STEP 4, and blank paper printing is performed on the recording paper P 1 reversed by the passage through the reverse conveyance path 81, and then the operations after STEP 5 are repeated.

  On the other hand, when the contamination level is equal to or greater than the second threshold (No in STEP 18), the conveyance control unit 107 determines the contamination level stored in the storage unit 104 when determining that the recording paper P1 for which blank printing has been completed cannot be reused. The initial value is reset (STEP 22). Further, the contamination degree change amount calculated by the contamination degree change amount calculation unit 106 is stored in the storage unit 104 (STEP 23). Then, the transport control unit 107 generates a paper discharge control signal similar to STEP 12 in order to discharge the recording paper P1, and outputs it from the input / output interface 108 (STEP 24). As a result, the recording paper P <b> 1 after the inspection in the image inspection apparatus 6 is discharged onto the discharge tray 72 by the rotation driving of the discharge roller pair 71. Further, the printing status flag stored in the storage unit 104 is also reset to front side printing (STEP 25). Thereafter, the process proceeds to STEP 3, and a new recording sheet P 1 is fed out from the paper feed cassette 31 to the main transport path 80, and then the operations after STEP 4 are repeated.

  When the cleaning function is executed as described above, the front surface printing and the back surface printing are alternately performed on the recording paper P1. Hereinafter, the above-described cleaning function will be briefly described based on the change in the amount of dirt on the recording paper P1 in the front surface printing. By the first blank paper printing on the surface of the recording paper P1, as shown in FIG. 7A, the toner stain on the main conveyance path 80 becomes a toner image (dirt image) 500 and is formed on the surface of the recording paper P1. .

  As the recording paper P1 passes through the image inspection device 6, image data based on the dirty image 500 of the recording paper P1 is given to the control device 10 as a contamination level detection signal. In the control device 10, the contamination level calculation unit 105 calculates the concealment rate (region area of the contamination region) based on the number of pixels of the contamination image 500 from the contamination level detection signal, thereby acquiring the contamination level H1. Note that, as described above, the stain level may be calculated by a value obtained by integrating the toner density in each pixel constituting the stain image 500.

  Further, since the initial value of the contamination degree change amount is 0, it is the same value as the contamination degree H1. Then, the control device 10 compares the contamination degree change amount H1 with the cleaning execution threshold (first threshold) and determines whether or not to stop the cleaning function. On the other hand, the control device 10 determines the contamination state of the surface of the recording paper P1 as compared with the recording paper reuse threshold (second threshold) for the degree of contamination H1, and circulates the recording paper P1 to perform white paper printing. It is determined whether it can be executed again.

  Thereafter, after the first back side printing of the recording paper P1, the toner image (dirt image) is printed on the surface of the recording paper P1 by the second blank paper printing on the surface of the recording paper P1, as shown in FIG. ) 501 is additionally formed. As a result, the contamination level calculation unit 105 acquires the contamination level H2 (H2> H1) from the contamination level detection signal from the image inspection apparatus 6. On the other hand, the stain level change amount is a difference value ΔH (= H2−H1) from the stain level H1 in the first blank printing. Therefore, the control device 10 compares the contamination degree change amount ΔH with the first threshold value, while comparing the contamination degree H2 with the second threshold value. Further, the contamination degree change amount ΔH is also compared with the first contamination degree change amount H1, and when the contamination degree change amount H1 is equal to or greater than the contamination degree change amount H1, it is determined that there is a high possibility of device abnormality, and the high contamination degree meter Count the numbers.

  By repeating such blank paper printing, when the amount of change in the degree of contamination of the recording paper P1 falls below the cleaning threshold (first threshold), the controller 10 assumes that the main conveyance path 80 has been removed, and the control device 10 records. The paper P1 is discharged and the cleaning function is terminated. Further, if the high stain count value reaches a predetermined number without reducing the stain level change amount even if the white paper printing is repeated, the control device 10 determines that a device abnormality has occurred and performs the cleaning function. End. On the other hand, when the amount of change in the degree of smearing is reduced each time white paper printing is repeated, if the degree of smearing of the recording paper P1 exceeds the recording paper reuse threshold (second threshold), the control device 10 determines that the recording paper P1 It is determined that reuse is impossible, and a new recording sheet P1 is fed from the sheet feeding cassette 31 for blank sheet printing.

<Second Embodiment>
An image forming apparatus according to a second embodiment of the present invention will be described below with reference to the drawings. FIG. 8 is a block diagram illustrating a configuration of the image forming apparatus according to the present exemplary embodiment. In the configuration of the image forming apparatus in FIG. 8, devices and parts used for the same purpose as in the configuration of FIG. 1 are assigned the same reference numerals, and detailed descriptions thereof are omitted.

1. Configuration of Image Forming Apparatus As shown in FIG. 8, the image forming apparatus 1 a according to this embodiment is configured so that the image forming apparatus 1 according to the first embodiment (see FIG. 1) A circulation path 82 that branches and joins the transport path 81b is added. The circulation path 82 is a conveyance path that branches on the upstream side of the conveyance roller pair 94 with respect to the conveyance path 81a and merges between the reverse roller pair 85 and the conveyance roller pair 95 with respect to the conveyance path 81b. A conveyance roller pair 96 is provided on the path.

  Unlike the image forming apparatus 1 in the first embodiment, the image forming apparatus 1 a configured as described above has a circulation path 82 that relays the reverse conveyance path 81, and the recording paper P 1 conveyed through the circulation path 82 is Inversion by the inversion roller pair 85 is omitted. That is, when the recording paper P1 conveyed from the main conveyance path 80 to the conveyance path 81a is guided to the circulation path 82, it is conveyed by the conveyance roller pair 96 toward the conveyance roller pair 95 of the conveyance path 81b. Therefore, the recording paper P <b> 1 is conveyed to the registration roller pair 33 in the main conveyance path 80 without being reversed by the conveyance paths 81 a and 81 b and the circulation path 82. Accordingly, when the blank sheet is printed, the recording sheet P1 is conveyed using the circulation path 82, so that the same surface of the recording sheet P1 can be repeatedly subjected to blank sheet printing.

2. Cleaning Function Unlike the image forming apparatus 1 according to the first embodiment (see FIG. 1), the image forming apparatus 1a having the above configuration performs blank paper printing by circulating conveyance of the recording paper P1 using the circulation path 82, and has a cleaning function. Run. The operation for executing this cleaning function will be described below with reference to the drawings. 9 and 10 are flowcharts showing a control operation when the cleaning function is executed.

  Note that the configuration for performing the cleaning function in the image forming apparatus 1a of the present embodiment is the configuration shown in the block diagram of FIG. 4 as in the image forming apparatus 1 of the first embodiment. Therefore, in the present embodiment, the control device 10 illustrated in FIG. 4 executes the control operation according to the operation flow illustrated in FIGS. 9 and 10, so that the image forming apparatus 1 a performs white paper printing using the recording paper P 1. Execute the cleaning function. Also, in the flowcharts of FIGS. 9 and 10, steps showing the same operations as those in the flowcharts of FIGS. 5 and 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

  When the control operation of the blank printing is started (STEP 1), the control device 10 resets the high stain count value, the stain detection value, and the stain change value stored in the storage unit 104 to initial values ( (Step 2). Then, the recording paper P1 accommodated in the paper feed cassette 31 is fed out to the main conveyance path 80 (STEP 3), and blank paper printing is performed by the image forming device 4 and the fixing device 5 (STEP 4), and then the image inspection device. 6 is performed (STEP 5).

  According to the above STEP 3 to STEP 5, white paper is printed on the recording paper P 1, and when the control device 10 receives the smear level detection signal from the image inspection apparatus 6 by the input / output interface 108, in this embodiment, first, the smear level calculation is performed. The unit 105 calculates the degree of contamination of the recording paper P1 (STEP 9). Then, the contamination level change amount calculation unit 106 calculates the contamination level change amount from the difference between the contamination level calculated in SETP9 and the previous contamination level (STEP 10), and the transport control unit 107 calculates the contamination level. The amount of change is compared with the cleaning execution threshold (first threshold) (STEP 11). At this time, if the contamination degree change amount is equal to or smaller than the first threshold value (Yes in STEP 11), the discharge roller pair 71 is driven to rotate and the recording paper P is discharged to the discharge tray 72 (STEP 12). End execution.

  On the other hand, when the contamination degree change amount is larger than the first threshold (No in STEP 11), the conveyance control unit 107 receives the contamination degree change amount from the contamination degree change amount calculation unit 106, and is stored in the storage unit 104 last time. (STEP 13). If the calculated stain level change amount is equal to or greater than the previous stain level change amount (Yes in STEP 13), the conveyance control unit 107 counts the high stain level count value once (STEP 14). It is confirmed whether or not the count value has reached a predetermined number (STEP 15). At this time, if the high stain count value reaches the predetermined number (YES in STEP 15), the recording roller P is driven to rotate and the recording paper P is discharged to the discharge tray 72 (STEP 16). Thereafter, the image forming apparatus 1a informs the outside of the occurrence of the apparatus abnormality by a display operation or the like in the operation unit 8 (STEP 17), and ends the execution of the cleaning function.

  In addition, when the calculated contamination degree change amount is smaller than the previous contamination degree change amount (No in STEP 13), or when the high contamination degree count value has not reached the predetermined number of times (NO in STEP 15), the conveyance is performed. The control unit 107 compares the calculated stain level with the recording paper reuse threshold (second threshold) (STEP 18). At this time, if the contamination level is lower than the second threshold (YES in STEP 18), first, the calculated contamination level and the contamination level change amount are stored in the storage unit 104 (STEP 19). Then, the conveyance control unit 107 generates a circulation control signal so that the recording paper P1 is circulated through the conveyance paths 81a and 81b and the circulation path 82, and the conveyance rollers of the conveyance path 81b and the circulation path 82 are respectively input from the input / output interface 108. The data is output to the pairs 95 and 96 (STEP 30).

  As a result, the recording paper P1 that has passed through the image inspection apparatus 6 by the transport roller pair 93 is guided to the circulation path 82 via the transport path 81a by a guide (not shown), and then recorded by the rotational drive of the transport roller pair 96. The paper P1 passes through the circulation path 82 and moves to the transport path 81b. Thereafter, the conveyance roller pair 95 is driven to rotate, whereby the recording paper P1 moves along the conveyance path 81b and is guided to the registration roller pair 33 in the main conveyance path 80. In this way, the recording paper P1 sequentially passes through the transport path 81a, the circulation path 82, and the transport path 82a, so that the same surface as the previous printing surface is set as the printing surface in the recording paper P1. Thereafter, the process proceeds to STEP 4, and blank sheet printing is performed on the transport path 81 a, the circulation path 82, and the recording paper P 1 circulated by passing through the transport path 82 a, and then the operations in STEP 5 and subsequent steps are repeated.

  On the other hand, when the contamination level is equal to or greater than the second threshold (No in STEP 18), the contamination level stored in the storage unit 104 is reset to an initial value (STEP 22), and the contamination level calculated by the contamination level change amount calculation unit 106 is reset. The amount of change is stored in the storage unit 104 (STEP 23). Then, the transport control unit 107 confirms whether the blank page printing on the recording paper P1 is the front side printing or the back side printing based on the printing status flag stored in the storage unit 104 (STEP 31).

  At this time, when the blank paper printing on the recording paper P1 is the front surface printing (Yes in STEP 31), the conveyance control unit 107 outputs a reverse control signal (STEP 20). Thus, after the recording paper P1 that has passed through the image inspection apparatus 6 is guided to the reverse conveyance path 81, it is reversed by the rotational driving of the conveyance roller pairs 94 and 95 and the reverse roller pair 85, and the registration in the main conveyance path 80 is performed. Guided to roller pair 33. After that, when the printing status flag in the storage unit 104 is reversed and stored so as to indicate the reverse side printing (STEP 21), the process proceeds to STEP 4, and blank paper printing is performed on the recording paper P1 reversed by passing through the reverse conveyance path 81. After the execution, the operation from STEP5 is repeated.

  On the other hand, when the blank paper printing on the recording paper P1 is the reverse side printing (No in STEP 31), the paper discharge roller pair 71 is driven to rotate and the recording paper P1 is discharged onto the paper discharge tray 72 (STEP 24). In the storage unit 104, the printing status flag is reset to a value indicating front side printing (STEP 25). Thereafter, the process proceeds to STEP 3, and a new recording sheet P 1 is fed out from the paper feed cassette 31 to the main transport path 80, and then the operations after STEP 4 are repeated.

  By executing the cleaning function described above, in this embodiment, unlike in the first embodiment, blank paper printing (front surface printing) is repeatedly performed on the surface of the recording paper P1, and the degree of contamination is reduced. When the usage threshold (second threshold) is exceeded, the printing is switched to blank paper printing (backside printing) for the back side of the recording paper P1. Then, each time the white paper printing is repeated after switching to the white paper printing on the back surface of the recording paper P1, it is determined whether or not the recording paper P1 can be reused by comparing the degree of contamination with the second threshold value.

  As described above, in this embodiment, when the cleaning function is executed, the front surface printing and the back surface printing are not performed alternately as in the first embodiment, and the front surface printing is repeatedly performed and then the back surface printing is repeatedly performed. . Therefore, when the front surface printing and the back surface printing are alternately performed as in the case of the first embodiment, it is inevitably necessary to perform double-sided printing, and there is a possibility that blank paper printing is performed wastefully. On the other hand, in the present embodiment, when the cleaning function is executed, the front side printing of the recording paper P1 is repeated and then switched to the back side printing. Can be stopped. Therefore, the image forming apparatus according to the present embodiment does not need to repeat the front surface printing and the rear surface printing alternately as in the first embodiment when the cleaning function is performed, and can reduce the execution time and power consumption. Can be reduced.

<Third Embodiment>
An image forming apparatus according to a third embodiment of the present invention will be described below with reference to the drawings. Similar to the image forming apparatus of the second embodiment, the image forming apparatus of the present embodiment has the configuration shown in the schematic configuration diagram of FIG. Therefore, hereinafter, the configuration and operation for executing the cleaning function in the image forming apparatus of the present embodiment will be described with reference to the block diagram of FIG. 11 and the flowcharts of FIGS. 12 and 13. In the configuration of FIG. 11, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and detailed descriptions thereof are omitted. Also, in the flowcharts of FIGS. 12 and 13, steps showing the same operations as those in the flowcharts of FIGS. 9 and 10 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 11, the control device 10a in the image forming apparatus 1a of the present embodiment has a cleaning function completion timing and a discharge of the recording paper P1 with respect to the configuration of the control device 10 in the first and second embodiments. The timing prediction unit 110 that predicts the paper timing is added. As will be described later, the timing prediction unit 110 determines the end timing of the cleaning function, the discharge timing of the recording paper P1, and the discharge timing of the recording paper P1, based on the degree of contamination and the amount of change in the recording paper P2 that has been circulated a predetermined number of times and printed on white paper Predict inversion timing.

  The control device 10a configured as described above performs a cleaning function by operating according to the flowcharts of FIGS. When the control device 10a starts the blank printing control operation (STEP 1), the control device 10a performs a reset operation in the storage unit 104 (STEP 2). After that, the recording paper P1 is fed from the paper feed cassette 31 and blank paper printing is performed, and then the smear level detection operation by the image inspection apparatus 6 is performed (STEP 3 to STEP 5). In the present embodiment, unlike the first and second embodiments, the storage unit 104 of the control device 10a stores the number of times of blank paper printing instead of the high stain degree count value. Then, after the stain level calculation unit 105 calculates the stain level of the recording paper P1 (STEP 9), the stain level change amount calculation unit 106 calculates the stain level change amount (STEP 10).

  Thereafter, the conveyance control unit 107 compares the contamination degree change amount with the cleaning execution threshold (first threshold) (STEP 11). At this time, if the contamination degree change amount is equal to or smaller than the first threshold value (Yes in STEP 11), the discharge roller pair 71 is driven to rotate to discharge the recording paper P1 to the discharge tray 72 (STEP 12). End execution. On the other hand, if the stain level change amount is larger than the first threshold value (No in STEP 11), the conveyance control unit 107 checks whether or not the number of times of blank paper printing has reached the first predetermined number of times (STEP 40). The first predetermined number of times is set to two or more times, and is set by, for example, the number of times of blank paper printing (predicted number of times of printing) required for predicting the end timing of the cleaning function. Alternatively, it may be set as the minimum number of times that the effect of the cleaning function can be obtained.

  When the number of times of blank paper printing is smaller than the first predetermined number of times (the number of times of printing for prediction) (No in STEP 40), the conveyance control unit 107 calculates the number of times of blank paper printing after counting the number of times of blank paper printing (STEP 41). The storage unit 104 stores the contamination level and the contamination level change amount (STEP 42). Then, the control device 10a generates a circulation control signal by the conveyance control unit 107 and outputs it from the input / output interface 108, thereby circulating the recording paper P1 through the conveyance paths 81a and 81b and the circulation path 82 (STEP 43). ), The process proceeds to STEP4, and blank paper printing is executed again.

  In this way, if the amount of change in the smear level becomes equal to or less than the first threshold value while the blank paper printing of the recording paper P1 is repeated until the number of blank paper prints reaches the first predetermined number of times (Yes in STEP 11). Then, the recording paper P1 is discharged (STEP 12), and the execution of the cleaning function is finished. On the other hand, if the number of times of blank printing has reached the first predetermined number of times without the stain level change amount being equal to or less than the first threshold (YES in STEP 40), the conveyance control unit 107 receives a stain level change amount calculation unit 106 from the stain level change amount calculation unit 106. The degree change amount is received and compared with the previous stain degree change amount stored in the storage unit 104 (STEP 13).

  In the present embodiment, when the calculated stain level change amount is equal to or greater than the previous stain level change amount (Yes in STEP 13), the transport control unit 107 determines that an apparatus abnormality has occurred. The roller pair 71 is driven to rotate, and the recording paper P is discharged onto the paper discharge tray 72 (STEP 16). Thereafter, the image forming apparatus 1a informs the outside of the occurrence of the apparatus abnormality by a display operation or the like in the operation unit 8 (STEP 17), and ends the execution of the cleaning function.

  On the other hand, when the calculated stain degree change amount is smaller than the previous stain degree change amount (No in STEP 13), the timing prediction unit 110 determines the recording paper P1 based on the calculated stain degree and the stain degree change amount. The paper discharge timing and reversal timing and the end timing of the cleaning function are predicted and stored in the storage unit 104 (STEP 44). At this time, the timing prediction unit 110 calculates a limit number of times (reuse limit number) that the same surface of the recording paper P1 can be reused for blank printing as the reversal timing and discharge timing of the recording paper P1. Similarly, the timing prediction unit 110 calculates, as the end timing of the cleaning function, the number of repetitions of blank paper printing (cleaning end count) at which a sufficient cleaning effect is obtained.

  Thereafter, the transport control unit 107 refers to the storage unit 104 and confirms whether or not the number of times of blank printing has reached the reuse limit number (STEP 45). In other words, the conveyance control unit 107 determines whether or not the limit for blank paper printing on the same surface of the recording paper P1 has been reached. Then, when the number of times of blank paper printing reaches the reuse limit number (YES in STEP 45), it is confirmed from the printing status flag stored in the storage unit 104 whether or not the blank paper printing by the recording paper P1 is the front surface printing ( (STEP 46).

  At this time, when the blank paper printing on the recording paper P1 is the front surface printing (Yes in STEP 46), the conveyance control unit 107 outputs a reverse control signal (STEP 20). As a result, the recording paper P <b> 1 that has passed through the image inspection apparatus 6 is reversed by passing through the reverse conveyance path 81 and is guided to the main conveyance path 80. On the other hand, when the blank paper printing on the recording paper P1 is the reverse side printing (No in STEP 46), after the recording paper P1 is discharged to the paper discharge tray 72 (STEP 24), the same as in STEP 3, from the paper feed cassette 31. A new recording paper P1 is fed out to the main conveyance path 80 (STEP 47).

  When either the reversing operation of the recording paper P1 in STEP 20 or the feeding operation of the recording paper P1 in STEP 47 is executed, the timing prediction unit 110 newly sets the reuse limit count, and the storage unit 104 The reusable limit number stored in is updated (STEP 48). At this time, in the storage unit 104, the printing status flag is inverted and stored together with the update of the reuse limit count.

  If the number of times of blank paper printing has not reached the reusable limit number (NO in STEP 45), the conveyance control unit 107 checks whether or not the number of times of blank paper printing has reached the number of cleaning end times (STEP 49). Then, when the number of times of blank paper printing reaches the number of times of cleaning completion (YES in STEP 49), the conveyance control unit 107 determines that the effect of the cleaning function by blank paper printing has been obtained. Is discharged (STEP 12), and the execution of the cleaning function is terminated. On the other hand, when the cleaning completion count has not been reached (No in STEP 49), the circulation control signal is generated by the conveyance control unit 107 and output from the input / output interface 108 as in STEP 43, whereby the recording paper P1 is conveyed in the conveyance path. It is made to circulate by 81a, 81b and the circulation path 82 (STEP 30).

  As described above, when the reuse limit count is updated in STEP 48 or the recording paper P1 is circulated and conveyed in STEP 30, the control device 10a counts and updates the number of times of blank paper stored in the storage unit 104 once. (STEP 50). Then, blank paper printing is performed by the image forming device 4 and the fixing device 5 on the recording paper P1 passing through the main conveyance path 80 (STEP 51), and then the process proceeds to STEP 45. Note that when the blank printing of STEP 51 is executed, the smear level detection operation by the image inspection apparatus 6 remains stopped. That is, the image inspection apparatus 6 is stopped in blank paper printing repeated after the completion timing of the cleaning function is predicted in STEP 44.

  By executing the cleaning function described above, in the present embodiment, unlike the second embodiment, first, blank paper printing (front surface printing) on the surface of the recording paper P1 is repeated a first predetermined number of times. At this time, when the stain level change amount falls below the cleaning execution threshold value (first threshold value), it is assumed that the main transport path 80 has been cleaned, and the execution of the cleaning function is terminated. On the other hand, when the number of times of blank paper printing reaches the first predetermined number without the stain level change amount falling below the first threshold, the control device 10a, based on the stain level and the stain level change amount acquired at the time of printing each blank page. And set the reuse limit count and the cleaning end count.

  At this time, for example, when the degree of contamination is high, it is determined that the number of times of blank paper printing needs to be increased, and the cleaning end count is set to be larger. For example, when there is no difference in the amount of change in the degree of stain or when the amount of change in the stain is relatively large, it is determined that the number of times that blank paper can be repeatedly printed on one side of the recording paper P1 is small, and the reuse limit Set a little. Furthermore, the reuse limit count is set every time the surface of the recording paper P1 that is the target of blank printing is switched. However, each time the blank printing target surface is switched, the number of repetitions of blank printing increases. It may be set.

  As described above, when the reuse limit count and the cleaning end count are set, first, the front side printing of the recording paper P1 is repeatedly executed, and when the blank paper printing count reaches the reuse limit count, the back side printing of the recording paper P1 is performed. Blank paper printing is executed. Thereafter, when the back side printing of the recording paper P1 is repeated for the set reuse limit number, the recording paper P1 is discharged, and a new recording paper P1 is supplied from the paper supply tray 31, Repeat blank printing by printing. Such an operation is repeated, and finally, when the number of times of blank paper printing reaches the number of times of cleaning completion, the recording paper P1 is discharged, and the execution of the cleaning function is ended.

  In the present embodiment, the prediction accuracy is increased by increasing the number of times for the first predetermined number of times that the blank printing is repeated in order to predict the reuse limit number and the cleaning process number. Therefore, the first predetermined number of times may be one in which a fixed number of two or more times is stored in the storage unit 104, or can be set by the user or the like through the operation unit 8 according to the required prediction accuracy. It doesn't matter as a thing. In this embodiment, the image forming apparatus has the same configuration as that of the second embodiment. However, in the case of the image forming apparatus similar to that of the first embodiment, the front surface printing and the back surface printing are alternately performed. The use limit count is used only at the discharge timing for newly feeding the recording paper P1.

<Fourth Embodiment>
An image forming apparatus according to a fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 14 is a block diagram illustrating a configuration of the image forming apparatus according to the present exemplary embodiment. In the configuration of the image forming apparatus in FIG. 14, devices and parts used for the same purpose as those in the configuration of FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

1. Configuration of Image Forming Apparatus As shown in FIG. 14, the image forming apparatus 1b of the present embodiment feeds recording paper P1 from the outside of the apparatus to the image forming apparatus 1a (see FIG. 8) in the second embodiment. A possible manual feed tray 83 is added and the reverse conveyance path 81 and the circulation path 82 are omitted. The manual feed tray 83 has a paper feed roller pair 97 on the apparatus side so as to feed the recording paper P1 to the upstream side of the transport roller pair 91 in the main transport path 80. Accordingly, the recording paper P1 on the manual feed tray 83 is sent out one by one from the uppermost layer toward the main transport path 80 by the rotational driving of the paper feed roller pair 97.

2. Cleaning Function Unlike the image forming apparatus 1a of the second embodiment (see FIG. 8), the image forming apparatus 1b having the above configuration does not have a path for circulating the recording paper P1 in the apparatus. Therefore, in this embodiment, when the recording paper P1 becomes reusable when the cleaning function is executed, the reusable recording paper P1 is loaded on the manual feed tray 83 by the user. The operation for executing this cleaning function will be described below with reference to the drawings. 15 and 16 are flowcharts showing the control operation when the cleaning function is executed.

  Note that the configuration for performing the cleaning function in the image forming apparatus 1b of the present embodiment is the configuration shown in the block diagram of FIG. 4 as in the image forming apparatus 1a of the second embodiment. Therefore, in the present embodiment, the control device 10 shown in FIG. 4 executes the control operation according to the operation flow shown in FIGS. 15 and 16, so that the image forming apparatus 1b prints blank paper using the recording paper P1. Execute the cleaning function. In the flowcharts of FIGS. 15 and 16, steps showing the same operations as those in the flowcharts of FIGS. 9 and 10 are denoted by the same reference numerals, and detailed description thereof is omitted.

  When the control device 10 starts the control operation for blank paper printing (STEP 1), after performing the reset operation in the storage unit 104, the control device 10 performs blank paper printing on the recording paper P1 fed from the paper feed cassette 31 and prints the blank paper. The degree of contamination of the subsequent recording paper P1 is detected (STEP3 to STEP5). Thereafter, the control device 10 rotates the paper discharge roller pair 71 to discharge the recording paper P2 that has passed through the image inspection device 6 to the paper discharge tray 72 (STEP 12). Then, after each of the contamination level calculation unit 105 and the contamination level change amount calculation unit 106 calculates the contamination level and the contamination level change amount, the conveyance control unit 107 sets the contamination level change amount as the cleaning execution threshold (first threshold). (STEP 9 to STEP 11).

  When the contamination degree change amount is equal to or less than the first threshold (YES in STEP 11), the control device 10 outputs a display control signal for notifying the completion of the cleaning function from the input / output interface 108 to the operation unit 8 (STEP 71). ). As a result, the display of the operation unit 8 displays the completion of the cleaning function, for example, “I will end the cleaning function”, and the execution of the cleaning function ends. On the other hand, when the contamination degree change amount is larger than the first threshold (No in STEP 11), the contamination degree change amount is received from the contamination degree change amount calculation unit 106, and the previous contamination degree change amount stored in the storage unit 104 is calculated. Compare (STEP 13).

  If the calculated contamination degree change amount is equal to or more than the previous contamination degree change amount (Yes in STEP 13), the conveyance control unit 107 counts the high contamination degree count value and determines whether or not the predetermined number of times has been reached. Is confirmed (STEP14, STEP15). At this time, if the high contamination count value reaches the predetermined number of times (Yes in STEP 15), the conveyance control unit 107 displays a device error such as “Please use maintenance service” on the display unit of the operation unit 8, for example. The display indicating the occurrence is performed (STEP 17), and the execution of the cleaning function is ended.

  In addition, when the calculated contamination degree change amount is smaller than the previous contamination degree change amount (No in STEP 13), or when the high contamination degree count value has not reached the predetermined number of times (NO in STEP 15), the conveyance is performed. The control unit 107 compares the calculated stain level with the recording paper reuse threshold (second threshold) (STEP 18). At this time, if the contamination level is lower than the second threshold (YES in STEP 18), the storage level 104 is stored in the storage unit 104 (STEP 19), and then the discharged recording paper P1 can be reused. A display control signal for informing this is output from the input / output interface 108 to the operation unit 8 (STEP 72).

  As a result, a display indicating that the discharged recording paper P1 can be reused is displayed on the display unit of the operation unit 8, for example, “Please set the recording paper on the paper discharge tray on the manual feed tray”. The Thereafter, the control device 10 confirms whether or not the recording paper P2 discharged to the paper discharge tray 72 is placed on the manual feed tray 83 (STEP 73). When the recording paper P2 is placed on the manual feed tray 83 (Yes in STEP 73), the conveyance support unit 107 generates a paper feed control signal for driving the paper feed roller pair 97 to rotate, and the input / output interface 108 is set. (STEP 74).

  Accordingly, by shifting to STEP 74, the paper feed roller pair 97 is rotationally driven, and the recording paper P 1 placed on the manual feed tray 83 is guided to the main conveyance path 80. Thereafter, the process proceeds to STEP 4, and blank paper printing is executed again for the recording paper P 2 fed from the manual feed tray 83. The manual feed tray 83 may be provided with an optical sensor, a contact sensor, or the like, and the control device 10 may determine whether to place the recording paper P2 on the manual feed tray 83 based on signals from these sensors. . Alternatively, the user who has placed the recording paper P2 on the manual feed tray 83 operates the operation unit 8, so that the control device 10 may determine whether to place the recording paper P1 on the manual feed tray 83.

  If the contamination level is equal to or greater than the second threshold (NO in STEP 18), the contamination level stored in the storage unit 104 is reset to an initial value, and the calculated contamination level change amount is stored in the storage unit 104 (STEP 22). , STEP23). Then, a display control signal for notifying that the discharged recording paper P1 cannot be reused is output from the input / output interface 108 to the operation unit 8 (STEP 75). As a result, a display indicating that the discharged recording paper P1 cannot be reused is displayed on the display unit of the operation unit 8, for example, “new recording paper is fed”. Thereafter, the process proceeds to STEP 3, and a new recording sheet P 1 is fed from the sheet feeding cassette 31 to the main conveyance path 80, and then blank sheet printing is executed.

  Thus, unlike the first to third embodiments, the present embodiment is not configured to have a circulation path for the recording paper P1, and therefore, when it is determined that the recording paper P1 on which blank paper printing has been performed is reusable, The user is requested to place the recording paper P2 on the manual feed tray 83 by the display on the display unit of the operation unit 8 or the like. Accordingly, even in an image forming apparatus having no circulation path, one sheet of recording paper P1 can be used for the execution of the cleaning function, so the number of recording sheets P1 used for the cleaning function is suppressed. it can.

  In this embodiment, when the cleaning function is executed, the surface printing of the recording paper P1 is repeatedly performed, and when it is determined that the recording paper P1 cannot be reused, a new recording paper P1 is fed. Similarly to the embodiment, the user may be notified to perform the back side printing of the recording paper P1. That is, when the cleaning function is executed, the front side printing of the recording paper P1 is repeatedly performed, and if it is determined that the recording paper P1 cannot be reused, the back surface of the recording paper P2 is displayed on the display unit of the operation unit 8 or the like. A request is made to place it on the manual feed tray 83 so that it is a target for blank paper printing.

  Similarly to the third embodiment, the recording paper P1 is repeatedly printed with a blank paper for the first predetermined number of times, thereby predicting the reuse limit number and the cleaning end number, and depending on the predicted reuse limit number and the cleaning end number. The user may be requested to place the recording paper P1 on the manual feed tray 83. Further, instead of the manual feed tray 83 in the present embodiment, an image forming apparatus including only a circulation path for circulating the recording paper P1 is used, and the front surface printing of the recording paper P1 is automatically repeated when the cleaning function is executed. It does n’t matter.

  In the first to fourth embodiments, the cleaning execution threshold value (first threshold value) and the recording paper reuse threshold value (second threshold value) have been described as single, but values can be set for each color of YMCK. It does n’t matter. For example, when comparing the color Y (Yellow) and the color K (Black) as the color of the toner stain, the effect of the toner stain due to the color K (Black) on the image quality of the image formed on the recording paper P1. Is big. Therefore, by setting the cleaning execution threshold value of the color K (Black) higher than the color Y (Yellow), the toner contamination by the color K (Black) that greatly affects the image quality is set to be completely removed. It is preferable.

  As for the recording paper reuse threshold (second threshold), for example, the value of the color K (Black) with a high toner density is set to be higher than the color Y (Yellow) with a low toner density. You may set so that the frequency | count that it can repeatedly perform blank paper printing becomes comparable. Further, when the cleaning execution threshold value (first threshold value) and the recording paper reuse threshold value (second threshold value) are set for each color of YMCK, the contamination level and the contamination level change amount are calculated for all the colors of YMCK. Then, it is preferable to end the cleaning function when the amount of change in the degree of contamination of each color of YMCK falls below the respective cleaning execution threshold (first threshold). On the other hand, when the stain level of at least one of the colors of YMCK exceeds the recording paper reuse threshold (second threshold), the back side printing of the recording paper P1 or the feeding of a new recording paper P1 is executed. It is preferable.

  The image forming apparatus according to the present invention may be an MFP (Multifunction Peripheral) having a copy function, a scanner function, a printer function, and a fax function as long as it performs the cleaning function in each of the above-described embodiments. It may be a printer, a copier, a facsimile, or the like. In addition, the structure of each part is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image reading apparatus 3 Paper feeding apparatus 4 Image forming apparatus 3 Fixing apparatus 6 Image inspection apparatus 7 Paper discharge apparatus 8 Operation unit 10, 10a Control apparatus 21 Light source 22 Solid-state image sensor 23 Imaging lens 24 Original glass plate 25 Reflective mirrors 26A to 26C Reflective mirror 27 Reference plate 31 Paper feed cassette 32 Paper feed roller pair 33 Registration roller pair 41 to 44 Photosensitive drum 45 Intermediate transfer section 46 Secondary transfer roller 51 Heating roller 52 Pressure roller 61 Light source 62 Solid-state image sensor 63 Imaging lens 64 Glass plate 65 Reflective mirror 66A-66C Reflective mirror 67 Reference plate 71 Discharge roller pair 72 Discharge tray 80 Main conveyance path 81 Reverse conveyance path 81a, 81b Conveyance path 82 Circulation path 83 Manual feed tray 85 Reverse roller pair 91-96 Transport roller pair 97 Feed roller pair 1 01 CPU
102 ROM
103 RAM
104 Storage Unit 105 Contamination Level Calculation Unit 106 Contamination Level Change Calculation Unit 107 Conveyance Control Unit 108 Input / Output Interface 109 Bus 110 Timing Prediction Unit

Claims (9)

A transfer unit that transfers the toner image to the recording paper, a fixing unit that fixes the toner image transferred to the recording paper by the transfer unit, a main conveyance path that conveys the recording paper to the transfer unit and the fixing unit, A paper feed unit that feeds the recording paper to the main transport path, and a paper discharge unit that discharges the recording paper on which the image is formed by passing through the transfer unit and the fixing unit through the main transport path to the outside of the apparatus. And an image forming apparatus having a cleaning function for removing dirt on the main conveyance path by blank paper printing in which the transfer operation by the transfer unit is stopped,
An image inspection unit that is disposed between the fixing unit and the paper discharge unit on the main conveyance path and inspects an image formed on the recording paper;
Based on the inspection result by the image inspection unit, a smear degree calculation unit that calculates the degree of smear transferred to the recording paper when performing blank paper printing;
A conveyance control unit for determining whether or not to pass the recording sheet again through the main conveyance path when executing the next blank sheet printing based on the degree of contamination of the recording sheet obtained by the contamination degree calculation unit; ,
With
When the cleaning function is executed and the blank printing is repeated a plurality of times, the conveyance control unit repeats the blank printing with the same recording paper until the degree of contamination of the recording paper exceeds the recording paper reuse threshold. An image forming apparatus characterized by determining. When the blank printing with the same recording paper is repeated, the smearing degree of the recording paper calculated by the smearing degree calculation unit and the smearing degree of the recording paper calculated by the previous white paper printing are determined. A dirt degree change amount calculating unit for calculating the degree of dirt change;
The conveyance control unit determines that the execution of the cleaning function is stopped when the amount of change in the degree of contamination of the recording paper obtained by the degree of contamination change calculation unit falls below a cleaning execution threshold. The image forming apparatus according to claim 1.   The conveyance control unit counts a state in which the amount of change in the degree of contamination of the recording paper in the continuous white paper printing does not decrease when the white paper is continuously printed during the execution of the cleaning function, and the count value is a predetermined value. The image forming apparatus according to claim 1, wherein when the value is exceeded, it is determined that an apparatus abnormality has occurred. Blank paper printing is repeated a predetermined number of times after the start of the execution of the cleaning function, and blank paper printing is repeated on the same recording paper based on the degree of dirt of the recording paper obtained by the smear degree calculation unit in each blank paper printing. A timing prediction unit that predicts the number of times that can be performed and sets it as the reuse limit number,
The said conveyance control part determines with repeating the blank paper printing by the same recording paper until the frequency | count of blank paper printing reaches | attains the said reusable limit frequency, It is any one of Claims 1-3 characterized by the above-mentioned. The image forming apparatus described. The timing prediction unit sets the number of times of blank paper printing to be repeated thereafter as the number of cleaning completions based on the degree of smearing of the recording paper obtained in each blank paper printing repeated a predetermined number of times after the start of execution of the cleaning function,
The image forming apparatus according to claim 4, wherein the conveyance control unit stops the execution of the cleaning function when the blank printing is performed for the number of times of the cleaning completion. A circulation path for circulating the recording paper that has passed through the image inspection unit;
When the conveyance control unit determines to repeat the blank printing with the same recording paper, the recording paper that has passed through the image inspection apparatus is circulated to the main conveyance path through the circulation path, and the blank printing is performed on the recording paper. The image forming apparatus according to claim 1, wherein the image forming apparatus is executed.   The image according to claim 6, wherein the circulation path includes a reversal conveyance path that reverses the surface of the recording paper, and performs blank paper printing on both sides of the recording paper during the execution of the cleaning function. Forming equipment. Each time the blank sheet is printed, the recording sheet that has passed through the image inspection unit is discharged to the discharge unit,
When the conveyance control unit determines that the blank printing with the same recording paper is to be repeated, it notifies the outside so that the recording paper discharged to the paper discharge unit after the white paper printing is placed on the paper feeding unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   When the conveyance control unit determines that the recording paper to be printed with blank paper is to be changed, the recording paper printed with the blank paper is discharged to the paper discharge unit, and another recording paper is then transferred from the paper supply unit to the main conveyance. The image forming apparatus according to claim 1, wherein the image forming apparatus is fed out to a path and printed with a blank sheet.

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