Image forming system and evaluation program

Abstract

To provide an image formation system capable of optimizing fixing conditions in various combinations of images and media.SOLUTION: An image formation system includes: an image forming section that forms an image on a recording medium with toner; a fixing section that fixes the image formed on the recording medium onto the recording medium; a reading section that reads the image fixed on the recording medium with a sensor including a plurality of light receiving elements to generate read image data; a rubbing section that can rub the image fixed on the recording medium; and a control section that causes the rubbing section to rub the fixed image and evaluate a fixing state of the toner on the basis of the read image data generated by reading the rubbed image by the reading section.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to an image forming system and an evaluation program. [Background technology]

[0002] In an electrophotographic image forming apparatus, for example, an electrostatic latent image formed by exposing a charged photosensitive member to light is developed with toner to form a toner image on the surface of the photosensitive member, and the toner image is then transferred to an intermediate transfer member, which then transfers the toner image onto paper.The toner image on the paper is then fixed by applying heat and pressure to form an image on the paper, etc.

[0003] The optimum fixing temperature for the fixing process varies depending on the media (recording medium), such as paper, and the image pattern to be formed on the media. However, currently, the fixing temperature is determined based on a relatively simple image pattern determined during the development stage, and is determined by referring to a temperature table that defines fixing temperatures for each of the roughly grouped media. As a result, the fixing state is not necessarily optimized. If the fixing state is not optimized, the toner image may peel off from the media, resulting in waste paper. Furthermore, with the increase in media types and the development of special color toners in recent years, the number of combinations of media and image patterns is increasing, making it difficult to respond to them using a temperature table.

[0004] The following prior art is disclosed in Patent Document 1: A patch image for evaluating fixability formed on recording paper is fixed at a predetermined fixing temperature, and then a portion of the patch image is rubbed with a rubbing roller. An optical sensor detects the respective densities of the rubbed and non-rubbed portions of the patch image, and the fixing temperature is adjusted so that the density ratio falls within a predetermined reference range, thereby optimizing the fixing temperature. Patent Document 2: The following prior art is disclosed: A gray fixability test image is formed on a transfer material, and after fixing, a portion of the fixability test image is rubbed with a pair of rubbing rollers. The densities of the non-rubbed and rubbed portions are detected by a density sensor that detects density using reflected light, and when the ratio of the density of the rubbed portion to the density of the non-rubbed portion is less than a predetermined value, the fixing temperature is optimized by increasing the fixing temperature. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-51056 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-221338 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned prior art detects the density of the non-rubbed and rubbed areas as the average density of each area of ​​a certain size. As a result, it is not possible to accurately detect localized fixing problems, and therefore it is not possible to accurately evaluate fixing problems across various images formed on media. This results in the problem that it is not possible to optimize fixing conditions for various combinations of images and media.

[0007] The present invention has been made to solve these problems, and has as its object to provide an image forming system and evaluation program that can optimize fixing conditions for various combinations of images and media. [Means for solving the problem]

[0008] The above-mentioned problems of the present invention are solved by the following means.

[0009] (1) An image forming system having an image forming unit that forms an image using toner on a recording medium, a fixing unit that fixes the image formed on the recording medium onto the recording medium, a reading unit that reads the image fixed on the recording medium with a sensor including multiple light-receiving elements and generates read image data, a rubbing unit that can rub the image fixed on the recording medium, and a control unit that rubs the fixed image with the rubbing unit, reads the rubbed image with the reading unit, and evaluates the fixing state of the toner based on the generated read image data.

[0010] (2) The image forming system described in (1) above, wherein the reading unit further reads the image on the recording medium that has not been rubbed to generate the read image data, and the control unit further detects worn paper based on the read image data of the image on the recording medium that has not been rubbed.

[0011] (3) The image forming system described in (1) or (2) above, wherein the reading unit has a predetermined resolution, and the control unit evaluates the fixing state based on the read image data read at the predetermined resolution.

[0012] (4) The image forming system according to any one of (1) to (3) above, wherein the reading unit is a line sensor in which a plurality of the light receiving elements are arranged in a predetermined direction.

[0013] (5) The image forming system described in (4) above, wherein the predetermined direction is the width direction of the recording medium, and the reading unit reads the image on the recording medium using the light receiving elements arranged in the width direction.

[0014] (6) The image forming system according to any one of (1) to (5) above, wherein the reading unit reads the image by detecting the color of the image on the recording medium for each of the light receiving elements.

[0015] (7) The image forming system according to any one of (1) to (5) above, wherein the reading unit reads the image by detecting the density of the image on the recording medium for each of the light receiving elements.

[0016] (8) An image forming system described in any one of (1) to (7) above, wherein the control unit evaluates the fixing state of the toner by comparing the read image data with reference image data generated by reading the recording medium that has not been rubbed after the image has been fixed using the reading unit.

[0017] (9) An image forming system described in any one of (1) to (7) above, wherein the control unit evaluates the fixing state of the toner by comparing the image data used when forming the image on the recording medium with the read image data as reference image data.

[0018] (10) The image forming system according to any one of (1) to (9) above, wherein the control unit changes the fixing conditions of the fixing unit when it determines that the fixing of the toner is insufficient.

[0019] (11) The image forming system according to (10), wherein the fixing conditions are at least one of fixing temperature, fixing speed, fixing pressure, and lighting control of a heater in the fixing unit.

[0020] (12) An image forming system described in any one of (1) to (11) above, wherein the rubbing unit has a first mechanism that brings the rubbing member into contact with and separates from the recording medium, and a second mechanism that changes the contact pressure when the rubbing member is brought into contact with the recording medium.

[0021] (13) The image forming system according to (12), wherein the rubbing members are arranged in a plurality in the width direction of the recording medium.

[0022] (14) An image forming system according to any one of (1) to (13) above, wherein the control unit evaluates the fixing state in one of two switchable modes: a first mode for evaluating the fixing state during execution of a print job, and a second mode for evaluating the fixing state before execution of the print job.

[0023] (15) The image forming system according to any one of (1) to (13), wherein the control unit evaluates the fixing state during execution of a print job and discharges the recording medium used for the evaluation as waste paper.

[0024] (16) The control unit compares the reference image data with the read image data, and if it determines that the position where the difference exceeds a predetermined threshold corresponds to the rubbed position, it evaluates that the toner is not fixed sufficiently, and if it determines that the position where the difference exceeds the threshold does not correspond to the rubbed position, it determines that the image defect has occurred due to a cause other than insufficient toner fixation, in an image forming system described in any of (1) to (15) above.

[0025] (17) The image forming system described in (16) above, wherein the control unit compares the reference image data and the read image data based on at least one of the difference in colorimetric value and the difference in density at corresponding positions.

[0026] (18) The image forming system according to (12) above, wherein the rubbing member has a comb shape having a plurality of teeth for contacting the recording medium.

[0027] (19) An image forming system described in any one of (1) to (18) above, wherein the control unit selectively determines the portion on the recording medium where the fixing state of the toner is to be evaluated based on image data of the image to be formed on the recording medium.

[0028] (20) An evaluation program for causing a computer to execute a process comprising the steps of: (a) rubbing a toner image formed and fixed on a recording medium with a rubbing section; (b) reading the rubbed image on the recording medium with a reading section having a sensor including multiple light-receiving elements to generate read image data; and (c) evaluating the fixing state of the toner based on the read image data. [Effects of the Invention]

[0029] After fixing on the recording medium, the toner fixing state is evaluated based on the image data generated by reading the rubbed image with multiple light-receiving elements, allowing for optimization of fixing conditions for a variety of image and media combinations. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a schematic diagram illustrating an image forming system. [Figure 2] FIG. 2 is a block diagram showing a hardware configuration of the image forming apparatus. [Figure 3] FIG. 2 is a block diagram showing the hardware configuration of the image inspection device. [Figure 4] FIG. 2 is a block diagram showing a hardware configuration of a post-processing device. [Figure 5] FIG. 2 is an explanatory diagram showing the configuration of a rubbing unit and an image reading unit of the image inspection device. [Figure 6] FIG. 2 is an explanatory diagram showing the configuration of a sensor and a rubbing member. [Figure 7] 10A and 10B are explanatory diagrams showing an image of reference image data and a toner image after rubbing; [Figure 8] 10 is a flowchart illustrating an example of the operation of the image forming system in creating reference image data. [Figure 9] 10 is a flowchart showing another example of the operation of the image forming system in creating reference image data. [Figure 10] 10 is a flowchart illustrating an example of the operation of the image forming system. [Figure 11]10 is a flowchart showing another example of the operation of the image forming system. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, identical elements are designated by the same reference numerals, and redundant description will be omitted. The dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions. In the present embodiment, "paper" is used as an example of a recording medium, but recording media also include various films and envelopes. Paper includes those made from plant-derived mechanical pulp and / or chemical pulp. Paper types (paper grades) include gloss paper (also called coated paper), matte paper, plain paper, fine paper, and high-gloss paper.

[0032] Fig. 1 is a schematic diagram showing an image forming system 1000 according to an embodiment of the present invention. Fig. 2 is a block diagram showing the hardware configuration of the image forming apparatus 100. Fig. 3 is a block diagram showing the hardware configuration of an image inspection apparatus 200. Fig. 4 is a block diagram showing the hardware configuration of a post-processing apparatus 300.

[0033] (Overall composition) 1, the image forming system 1000 includes an image forming apparatus 100, an image inspection apparatus 200, and a post-processing apparatus 300. Along the conveyance direction of the paper 900, the image forming apparatus 100, the image inspection apparatus 200, and the post-processing apparatus 300 are connected in this order from the upstream side.

[0034] (Image forming apparatus 100) Image forming apparatus 100 includes a control unit 110, a storage unit 120, a communication unit 130, an operation display unit 140, an image reading unit 150, an image control unit 160, and an image forming unit 170. These components are communicably connected to one another via a bus. Image forming apparatus 100 may be configured as an MFP (Multi Function Peripheral).

[0035] The control unit 110 is equipped with a CPU (Central Processing Unit) and various memories, and controls the above-mentioned units and performs various arithmetic processing according to a program. Furthermore, the control unit 110 can control the units of the image inspection device 200 and the post-processing device 300 by controlling them in cooperation with the control unit 210 of the image inspection device 200 and the control unit 310 of the post-processing device 300.

[0036] The storage unit 120 is configured by a solid state drive (SDD) or a hard disk drive (HDD), and stores various programs and various data.

[0037] The communication unit 130 is an interface for communicating between the image forming apparatus 100 and an external device. A network interface conforming to standards such as Ethernet (registered trademark), SATA, or IEEE1394 is used as the communication unit 130. Alternatively, various local connection interfaces such as wireless communication interfaces such as Bluetooth (registered trademark) or IEEE802.11 are used as the communication unit 130.

[0038] The operation display unit 140 includes a touch panel, a numeric keypad, a start button, a stop button, and the like, and is used to display various information and input various instructions.

[0039] The image reading unit 150 has a light source such as a fluorescent lamp and an imaging element such as a CCD (Charge Coupled Device) image sensor. The image reading unit 150 irradiates a document set at a predetermined reading position with light from the light source, photoelectrically converts the reflected light with the imaging element, and generates image data from an electrical signal.

[0040] The image control unit 160 performs layout processing and rasterization processing on the print data included in the print job or the like received by the communication unit 130, and generates image data in bitmap format.

[0041] A print job is a general term for a print command to image forming apparatus 100, and includes print data and print settings. Print data is data of a document to be printed, and may include various types of data, such as image data, vector data, and text data. Specifically, print data may be PDL (Page Description Language) data, PDF (Portable Document Format) data, or TIFF (Tagged Image File Format) data. Print settings are settings related to image formation on paper 900, and may include various settings such as the number of pages, number of copies, paper type, selection of color or monochrome, and page layout.

[0042] The image forming section 170 includes an image creating section 40, a fixing section 50, a paper feeding section 60, and a paper transport section .

[0043] The image forming unit 40 has image forming units 41Y, 41M, 41C, and 41K corresponding to the toners of the respective colors of Y (yellow), M (magenta), C (cyan), and K (black). Each image forming unit 41Y, 41M, 41C, and 41K forms a toner image 901 (see FIG. 5) on the photosensitive drum 42 through processes of charging, exposure, and development based on image data. Exposure is performed by scanning the photosensitive drum 42 with a laser beam. The toner images formed on the photosensitive drum 42 are sequentially superimposed and primarily transferred onto the intermediate transfer belt 43 by electrostatic force generated by a constant-voltage-controlled transfer voltage applied to the primary transfer roller 44. This results in the color toner image 901 being held on the intermediate transfer belt 43. The color toner image 901 on the intermediate transfer belt 43 is then secondarily transferred onto paper 900 by the secondary transfer roller 45. The toner image 901 constitutes an "image."

[0044] The fixing unit 50 includes a heating roller 51, a pressure roller 52, a heater 53, and a temperature sensor 54 (see FIG. 5). The heater 53 heats the heating roller 51. The temperature sensor 54 measures the temperature of the heating roller 51. The heating roller 51 and the pressure roller 52 are pressed together to form a fixing nip between them. The fixing unit 50 heats and presses the paper 900 conveyed to the fixing nip at the fixing nip, and rotates the heating roller 51 and the pressure roller 52, thereby melting and fixing the toner image 901 on the paper 900 to the surface of the paper 900.

[0045] After the toner image 901 is formed and fixed on one side of the paper 900, the paper 900 is transported to the switchback path 73 and turned over, so that the toner image 901 can be formed and fixed on the other side. In this way, images can be formed on both sides of the paper 900.

[0046] The heating roller 51 comprises, from the inside out, a cylindrical metal core, an elastic layer formed on the surface of the core and made of a material such as silicone rubber or foamed silicone rubber, and a release layer such as fluororesin. Multiple halogen lamp heaters 53 are arranged inside the core. Each of the heaters 53 can be divided into multiple partial heaters in the width direction of the paper 900 (a direction perpendicular to the paper 900 transport direction). Each of the heaters 53 can have a different heat distribution in the width direction of the paper 900. Therefore, by supplying or not supplying power to each heater 53 or partial heater, or by varying the amount of power supplied to each heater 53 or partial heater, the temperature distribution of the heaters 53 as a whole in the width direction of the paper 900 can be controlled (lighting control) to a desired temperature distribution.

[0047] Based on the temperature information from the temperature sensor 54, the heater 53 can be controlled so that the heating roller 51 reaches a fixing temperature that falls within the predetermined fixing conditions. In addition, in a first mode and a second mode, which are modes for evaluating the fixing state, which will be described later, the fixing state of the toner is evaluated based on image data read by the image inspection device 200 of the toner image 901 rubbed on the paper 900 after fixing, and the fixing conditions can be set or changed based on the evaluation results. In addition to the fixing temperature, the fixing conditions include the fixing speed, the fixing pressure, and the lighting control of the heater 53.

[0048] The paper feed unit 60 has a plurality of paper feed trays 61 and 62, and sends out the paper sheets 900 stored in the paper feed trays 61 and 62 one by one to a downstream paper transport path.

[0049] The paper transport unit 70 has a plurality of transport rollers for transporting the paper 900, and transports the paper 900 between the imaging unit 40, the fixing unit 50, and the paper feed unit 60. The plurality of transport rollers include a registration roller 71 for correcting the skew of the paper 900, and a loop roller 72 for forming a predetermined amount of loop in the paper 900.

[0050] The paper transport section 70 transports the paper 900 on which the image has been formed to a downstream device.

[0051] (Image inspection device 200) 3, the image inspection device 200 includes a control unit 210, a storage unit 220, a communication unit 230, a rubbing unit 240, and an image reading unit 250. These components are communicatively connected to one another via a bus.

[0052] The configurations of the control unit 210, the storage unit 220, and the communication unit 230 are the same as those of the image forming apparatus 100, and therefore a duplicated description will be omitted.

[0053] Control unit 210 can cooperate with control unit 110 of image forming apparatus 100 to control the above-mentioned units and perform various arithmetic processing, and inspect toner image 901 on paper 900. Control unit 210 may also independently control the above-mentioned units and perform various arithmetic processing, and inspect toner image 901 on paper 900.

[0054] Fig. 5 is an explanatory diagram showing the configuration of the rubbing unit 240 and the image reading unit 250 of the image inspection device 200. For ease of explanation, Fig. 5 also shows the fixing unit 50 and the control unit 110 of the image forming device 100.

[0055] The toner image 901 fixed on the paper 900 in the fixing unit 50 is rubbed by the plate-shaped rubbing member 241 of the rubbing unit 240. The displacement member 243 moves up and down under the control of the control unit 210. In conjunction with the up and down movement of the displacement member 243, the rubbing member 241 abuts against the paper 900, and abuts against the paper 900 with a predetermined contact pressure using the restoring force of the compressed spring 242. A support plate may be provided on the opposite side of the rubbing member 241, sandwiching the paper 900 on the transport path, to support the back side of the paper 900. One of the upper and lower parallel transport plates that make up the transport path may also serve as the respective support plate. Also, although the pair of upper and lower rubbing members 241 are shown at the same position in the transport direction in FIG. 5, they may be positioned offset in the transport direction. The control unit 210 moves the displacement member 243 in the opposite direction relative to the paper 900, thereby separating the rubbing member 241 from the paper 900. By adjusting the distance between the displacement member 243 and the paper 900 (more specifically, the conveyance path of the paper 900), it is possible to increase or decrease the contact pressure of the rubbing member 241 against the paper 900. The displacement member 243 and the spring 242 constitute a first mechanism and a second mechanism.

[0056] After a toner image 901 is formed and fixed on one side of the paper 900, the paper 900 can be conveyed to the image inspection device 200 after being turned over by the switchback path 73 and having a toner image 901 formed and fixed on the other side. The rubbing members 241 can be arranged on both sides of the conveyance path for the paper 900, sandwiching the conveyance path, to rub the toner images 901 on the front and back sides of the paper 900, respectively.

[0057] The image reading unit 250 includes a sensor 251 that includes a plurality of light receiving elements 252 (see FIG. 6). The sensor 251 can be, for example, a line sensor in which the plurality of light receiving elements 252 are arranged in a predetermined direction. The predetermined direction is, for example, the width direction of the paper 900 (a direction perpendicular to the conveyance direction of the paper 900). The sensor 251 has a predetermined resolution. The resolution of the sensor 251 is preferably 400 dpi or higher. For simplicity of explanation, the following description will be given taking the case where the sensor 251 is a line sensor as an example.

[0058] Fig. 6 is an explanatory diagram showing the configuration of the sensor 251 and the rubbing member 241. In Fig. 6, the conveying direction of the paper 900 is indicated by an arrow.

[0059] In the example of FIG. 6 , a plurality of light receiving elements 252 of the sensor 251, which is a line sensor, are arranged in a row in the width direction of the paper 900. A plurality of light emitting elements (LEDs) or the like may be arranged beside the light receiving elements 252 to emit linear light. Furthermore, a plurality of plate-like elements constituting the rubbing member 241 are arranged at positions corresponding to the light receiving elements 252. In this manner, the rubbing member 241 may have a comb-like shape having a plurality of teeth (plate-like elements) for contacting the paper 900. As the paper 900 is transported in contact with the respective rubbing members 241, the toner image 901 on the paper 900 is rubbed by the respective plate-like elements of the rubbing member 241. Then, as the paper 900 is transported, the light receiving elements 252 of the sensor 251 detect reflected light from the toner image 901, etc., and the entire toner image 901 on the paper 900 after rubbing (more specifically, the entire surface of the paper 900) is read by the sensor 251.

[0060] After a toner image 901 is formed and fixed on the paper 900, the image reading unit 250 reads the rubbed toner image 901 with a sensor 251 to generate read image data. The read image data is image data with a predetermined resolution. When a toner image 901 is formed and fixed on both sides of the paper 900, the toner images 901 fixed on both sides of the paper 900 are rubbed, and then read by sensors 251 arranged on both sides of the transport path of the paper 900, respectively, to generate read image data for the front and back sides of the paper 900.

[0061] The image reading unit 250 can generate read image data by reading the toner image 901 by detecting the color of the toner image 901 on the paper 900 for each light receiving element 252 of the sensor 251 .

[0062] The image reading unit 250 may generate read image data by reading the toner image 901 by detecting the density of the toner image 901 on the paper 900 for each light receiving element 252 of the sensor 251 .

[0063] The scanned image data is used to evaluate the toner fixing state. If the evaluation results indicate that the toner fixing state is insufficient, the fixing conditions are changed. Note that the paper 900 used to evaluate the toner fixing state may be determined to be waste paper.

[0064] (Post-processing device 300) 4, post-processing device 300 includes control unit 310, storage unit 320, communication unit 330, and post-processing unit 340. The configurations of control unit 210, storage unit 220, and communication unit 230 are the same as the configurations of the corresponding components of image forming apparatus 100, so redundant explanations will be omitted.

[0065] The control unit 310 cooperates with the control unit 110 of the image forming apparatus 100 to control the above-mentioned units and perform various arithmetic processing, thereby performing post-processing on the paper 90. The control unit 210 may independently control the above-mentioned units and perform various arithmetic processing, thereby performing post-processing on the paper 90.

[0066] The post-processing unit 340 performs various post-processing such as stapling, punching, booklet formation, etc. For example, the post-processing unit 340 has a stacking unit that stacks the paper sheets 900 and a staple unit, and after stacking multiple sheets 900 in the stacking unit, performs side-stitching using staples in the staple unit.

[0067] The paper 900 that has undergone post-processing is discharged to the paper output tray 341. Paper 900 that has been determined (detected) as waste paper by the image inspection device 200 is discharged to the paper output tray 342 without being subjected to post-processing. The waste paper includes the rubbed paper 900 that has been used in the evaluation of the toner fixing state based on the read image data generated by the image inspection device 200. The waste paper may further include paper 900 that has been determined to be defective (waste paper) based on the read image data of the toner image 901 that has been read by the sensor 251 without being rubbed by the rubbing member 241.

[0068] (Function of the control unit 110 of the image forming apparatus 100) The following describes the operation of the control unit 110 of the image forming apparatus 100. All or part of the operation described below may be performed by cooperation between the control unit 110 of the image forming apparatus 100 and the control unit 210 of the image inspection apparatus 200, or may be performed by the control unit 210 of the image inspection apparatus 200 alone.

[0069] The control unit 110 receives scanned image data from the image inspection device 200 and evaluates the toner fixing state based on the received scanned image data. Specifically, the control unit 110 evaluates the toner fixing state by comparing scanned image data generated by rubbing the toner image 901 on the paper 900 in the image inspection device 200 and then reading it with reference image data that serves as a basis for evaluating the toner fixing state, etc. The control unit 110 compares the reference image data with the scanned image data, and if the difference exceeds a predetermined threshold, determines that the toner fixing is insufficient. At this time, the comparison between the reference image data and the scanned image data can be performed for each corresponding pixel.

[0070] The control unit 110 can further detect worn paper by determining defects other than the toner fixing state based on the read image data of the toner image 901 that has not been rubbed on the paper 900. Specifically, the control unit 110 can detect worn paper by determining defects other than the toner fixing state by comparing the read image data of the toner image 901 that has not been rubbed with the reference image data. Defects other than the toner fixing state include stains and the like.

[0071] After fixing the toner image 901 on the paper 900, the control unit 110 can generate reference image data by reading the toner image 901 without rubbing it in the image inspection device 200. The toner image 901 read to generate the reference image data can be, for example, an image formed on the paper 900 as a product (printed matter).

[0072] The control unit 110 may use, as the reference image data, image data used when forming a toner image 901 (for example, an image of a product (printed matter)) on the paper 900 to be inspected. In this case, the reference image data may be converted so that the resolution of the reference image data is the same as the resolution of the read image data.

[0073] FIG. 7 is an explanatory diagram showing an image of the reference image data and a toner image 901 after rubbing.

[0074] Compared with the image of the reference image data, the toner image 901 after rubbing has been scraped off by rubbing. The scraping of the toner image 901 due to rubbing indicates that the toner is not sufficiently fixed to the paper 900. The scraping of the toner image 901 can be determined (detected) by comparing the reference image data with the scanned image data and determining whether the difference exceeds a predetermined threshold. The scraping of the toner image 901 can occur, for example, in a case where all layers of the toner image 901 formed by overlapping layers of the three primary colors (e.g., layers of C, M, and Y colors) of the color toner image 901 are scraped off, as shown in FIG. 7 . Another possible scraping of the toner image 901 is when only one or two of the upper layers of the three primary colors of the color toner image 901 are scraped off. Any of these scraping modes of the color toner image 901 can be determined (evaluated) based on the color or density of the toner image 901 detected by the sensor 251.

[0075] The control unit 110 compares the reference image data with the read data, and when it determines that a position (for example, pixel coordinates) where the difference exceeds a predetermined threshold corresponds to a rubbed position, it can determine (evaluate) that the toner is not sufficiently fixed. Specifically, the control unit 110 can perform this comparison by comparing the reference image data with the read image data based on at least one of the difference in colorimetric value and the difference in density at corresponding positions (for example, pixel coordinates).

[0076] The control unit 110 compares the reference image data with the read data, and if it determines that a position where the difference exceeds a predetermined threshold does not correspond to a rubbed position, it can determine (evaluate) that an image defect has occurred due to a cause other than insufficient toner fixing. A position (portion) in the toner image 901 that is not rubbed can be created, for example, by not placing the rubbing member 241 in a position that corresponds to some of the multiple light receiving elements 252. By creating a non-rubbed position in part of the toner image 901, it is possible to evaluate the toner fixing state in the rubbed portion, and also to evaluate image defects other than the toner fixing state in the non-rubbed portion.

[0077] The control unit 110 determines (evaluates) the fixing state in either a first mode in which the fixing state is determined (evaluated) during execution of a print job, or a second mode in which the fixing state is evaluated before execution of a print job. The first mode and the second mode can be configured to be mutually switchable. This switching can be set by the user for each print job or for all print jobs in common.

[0078] When the control unit 110 determines that the toner is not sufficiently fixed, it changes the fixing conditions of the fixing unit 50.

[0079] The control unit 110 determines (evaluates) the fixing state during execution of a print job, and discharges the paper 900 used for the determination to the paper discharge tray 342 as waste paper.

[0080] The control unit 110 can selectively determine a portion on the paper 900 for evaluating the toner fixing state based on image data of the toner image 901 to be formed on the paper 900. Specifically, the control unit 110 may, for example, selectively determine a portion in the image data where the density of the image (toner image 901) is equal to or greater than a predetermined threshold, and evaluate the toner fixing state in the determined portion (coordinate range). The portion for evaluating the toner fixing state may be a portion where the toner amount exceeds a predetermined threshold. When selectively determining a portion for evaluating the toner fixing state, the rubbing member 241 may be brought into contact only with the portion of the paper 900 corresponding to the determined portion.

[0081] The control unit 110 can change the evaluation level of the fixing state by changing the magnitude of the contact pressure of the rubbing member 241 on the paper 900. By increasing the contact pressure, the fixing conditions can be adjusted until the toner is fixed to the paper 900 at a level that can withstand a stronger load (rubbing force). On the other hand, by decreasing the contact pressure, the fixing conditions can be adjusted so that the toner is fixed to a level that does not peel off under a light load. This allows for flexible response to the level of fixing state desired by the customer.

[0082] 8 is a flowchart showing an example of the operation of the image forming system in creating reference image data. This flowchart can be executed by the control unit 110 of the image forming apparatus 100 in accordance with a program. This flowchart may also be executed by the control unit 110 of the image forming apparatus 100 and the control unit 210 of the image inspection apparatus 200 in cooperation with each other. All or part of this flowchart may also be executed independently by the control unit 210 of the image inspection apparatus 200 (the same applies to FIGS. 9 to 11).

[0083] The control unit 110 causes the fixing unit 50 to fix the toner image 901 onto the paper 900 (S101).

[0084] The control unit 110 reads the toner image 901 on the paper 900 by the image reading unit 250 of the image inspection device 200 while separating the rubbing member 241 from the paper 900 (S102). In other words, the control unit 110 reads the toner image 901 on the paper 900 without rubbing it.

[0085] The control unit 110 stores the image data generated by reading as reference image data in the storage unit 120. The reference image data may be stored in the storage unit 220 of the image inspection device 200.

[0086] FIG. 9 is a flowchart showing another example of the operation of the image forming system in creating reference image data.

[0087] The control unit 110 stores the image data of the product as reference image data in the storage unit 120 (S201). The control unit 110 may store the reference image data in the storage unit 220 of the image inspection device 200. As described above, the control unit 110 may convert the reference image data so that the resolution of the reference image data is the same as the resolution of the read image data.

[0088] FIG. 10 is a flowchart showing an example of the operation of the image forming system.

[0089] Steps S301 to S306 are for adjusting the fixing conditions before the final printing (product image formation), and are executed as a second mode for evaluating the fixing state before the execution of a print job.

[0090] The control unit 110 causes the fixing unit 50 to fix the toner image 901 on the paper 900 (S301).

[0091] The control unit 110 causes the image reading unit 250 of the image inspection device 200 to bring the rubbing member 241 into contact with the paper 900, thereby rubbing the toner image 901 on the paper 900 (S302).

[0092] The control unit 110 generates read image data by reading the toner image 901 on the paper 900 (S303). That is, the control unit 110 generates read image data by rubbing the toner image 901 on the paper 900 and then reading it.

[0093] The control unit 110 compares the read image data with the reference image data to evaluate the fixing state of the toner image 901 on the paper 900 (S304).

[0094] If the control unit 110 determines that the fixing is sufficient as a result of the evaluation of the fixing state (S305: YES), it performs the final printing (image formation of the product) (S307). Note that, before the final printing is performed, the rubbing member 241 is separated from the paper 900 (more specifically, separated from the transport path of the paper 900) to prevent the quality of the printed matter from being impaired.

[0095] If the control unit 110 determines that the fixing is insufficient (S305: NO), it changes the fixing conditions (S306). The changes in the fixing conditions include at least one of (1) increasing the fixing temperature, (2) slowing the fixing speed (the speed at which the paper 900 passes through the fixing unit 50), (3) increasing the fixing pressure (the pressure applied to the paper 900 at the fixing nip), and (4) changing the lighting control of the heater 53. More specifically, possible changes in the fixing conditions include increasing the fixing temperature by 10°C, reducing the fixing speed to 80% of the previous value, and increasing the lighting level of the heaters on the front side of the image forming apparatus 100 in the width direction of the paper 900. The reason for changing the fixing conditions (4) is as follows: In the width direction of the paper 900, the temperature of the heating roller 51 and the like may become uneven, which may result in uneven heating of the paper 900 and result in poor fixing. For example, by increasing the lighting power (lighting ratio) of the partial heater of the heater 53 of the fixing unit 50 at the position where the fixing failure occurs, the fixing failure can be reduced locally.

[0096] The number of sheets of paper 900 used to evaluate the toner fixing state in steps S301 to S305 is not limited to one, but may be multiple.

[0097] FIG. 11 is a flowchart showing another example of the operation of the image forming system.

[0098] Steps S401 to S408 are for adjusting the fixing conditions during the actual printing, and are executed as a first mode for evaluating the fixing state during the execution of a print job.

[0099] The control unit 110 determines whether to evaluate the fixing state during execution of the final printing print job (S401). For example, the control unit 110 may determine to evaluate the fixing state every time fixing of the toner image 901 to a predetermined number of sheets of paper 900 is completed during final printing. The predetermined number of sheets is, for example, 10 sheets, 100 sheets, or 1000 sheets, and may be set appropriately through experiments from the viewpoint of the stability of the fixing state.

[0100] When the control unit 110 determines not to evaluate the fixing state (S401: NO), it continues to perform image formation for the actual printing (S402).

[0101] When the control unit 110 determines that the fixing state is to be evaluated (S401: YES), the process proceeds to step S403 and continues the process.

[0102] Steps S403 to S408 are the same as steps S301 to S306 in FIG. 10, and therefore a description thereof will be omitted.

[0103] After changing the fixing conditions, if the control unit 110 determines that the fixing is sufficient (S407: YES), it resumes the image formation for the actual printing (S409).

[0104] If the control unit 110 determines that the fixing is insufficient after changing the fixing conditions (S407: NO), it repeats steps S403 to S408 until it determines that the fixing is sufficient.

[0105] The embodiment provides the following advantages.

[0106] After fixing on the recording medium, the toner fixing state is evaluated based on the image data generated by reading the rubbed image with multiple light-receiving elements, allowing for optimization of fixing conditions for a variety of image and media combinations.

[0107] Furthermore, the image on the recording medium that has not been rubbed is read to generate read image data, and waste paper is detected based on the read image data of the image that has not been rubbed. This allows the image reading means to be used for both evaluating the toner fixing state and evaluating other things, thereby reducing the scale of the device and shortening the inspection time.

[0108] Furthermore, the scanned image data is read at a predetermined resolution, and the fixing state is evaluated based on the scanned image data at the predetermined resolution, thereby enabling the fixing state to be evaluated with high accuracy for a variety of images.

[0109] Furthermore, the image is scanned using a line sensor with multiple light-receiving elements arranged in a predetermined direction. This allows for easier and more efficient evaluation of the fixation state and other characteristics. The advantages of using a relatively high-resolution line sensor compared to scanning an image using a densitometer are described below. Density-based differential evaluation requires a certain area of ​​the image to be inspected, limiting the number of image patterns that can be evaluated. Therefore, even if the fixing temperature is adjusted using a specific evaluation chart, if the image the customer requests has localized areas of high toner mass within the surface of the paper 900, the fixing temperature may be set lower than the appropriate value in those areas. Furthermore, density-based differential evaluation can reduce the accuracy of fixing state detection due to the influence of color differences on density measurements. For example, if a toner image contains multiple toner layers, even if the toner in the upper layer is not sufficiently fixed, while the toner in the lower layer is, the fixing temperature may not be optimized, and the densitometer may measure the density at a value above a predetermined threshold due to the influence of the toner in the lower layer, resulting in an erroneous evaluation that the toner is sufficiently fixed. This problem can be overcome by reading the image with a relatively high-resolution line sensor in which a plurality of light-receiving elements are arranged in a predetermined direction.

[0110] Furthermore, the arrangement direction of the light receiving elements of the sign sensor is set to the width direction of the recording medium, which makes it possible to more simply and efficiently improve the accuracy of evaluation of the fixing state, etc.

[0111] Furthermore, the image is read by detecting the color of the image on the recording medium for each light-receiving element. This allows for highly sensitive evaluation of the toner fixing state, even in cases where only the upper layer of the toner image that makes up the image has peeled off. In particular, when the image is a color image made up of multiple overlapping toner layers of primary colors, peeling of only the upper layer can be detected with high accuracy.

[0112] In addition, the image is read by detecting the density of the image on the recording medium for each light receiving element, which allows for highly accurate evaluation of the fixing state and other conditions using a simple device.

[0113] Furthermore, the toner fixation state is evaluated by comparing the scanned image data with reference image data generated by scanning a recording medium that has not been rubbed after the image has been fixed. This makes it easier and more flexible to generate a reference image.

[0114] Furthermore, image data used when forming an image on a recording medium is used as reference image data, which makes it easier to generate a reference image.

[0115] Furthermore, if the toner fixing is judged to be insufficient, the fixing conditions of the fixing unit are changed, thereby effectively suppressing the generation of waste paper due to poor fixing.

[0116] Furthermore, the fixing conditions are set to at least one of the fixing temperature, fixing speed, fixing pressure, and heater control of the fixing unit, which makes it possible to simply and effectively prevent paper waste due to insufficient fixing.

[0117] Furthermore, the rubbing unit that rubs the image includes a first mechanism that brings the rubbing member into contact with and away from the recording medium, and a second mechanism that changes the contact pressure when the rubbing member is brought into contact with the recording medium, which makes it possible to evaluate the fixing state and other conditions with a simpler configuration.

[0118] Furthermore, a plurality of rubbing members are arranged in the width direction of the recording medium, which allows the surface of the recording medium to be rubbed effectively and easily over a wide range.

[0119] Furthermore, the fixing state is evaluated in either a first mode, which evaluates the fixing state during execution of a print job, or a second mode, which evaluates the fixing state before execution of a print job, which can be switched between. This allows for more flexible evaluation of the fixing state, etc.

[0120] The fixing state is evaluated during the execution of a print job, and the recording medium used for the evaluation is discharged as waste paper. This allows the fixing state to be stabilized without stopping the print job, even when image formation is performed for a relatively long period of time.

[0121] Furthermore, by comparing the reference image data with the scanned image data, if it is determined that the position where the difference exceeds a predetermined threshold corresponds to the rubbed position, it is evaluated that the toner fixing is insufficient. If it is determined that the position where the difference exceeds the threshold does not correspond to the rubbed position, it is determined that the image defect is caused by a cause other than insufficient toner fixing. This makes it easier to distinguish between the evaluation of the fixing state and the evaluation of image defects other than the fixing state.

[0122] Furthermore, the reference image data and the scanned image data are compared based on at least one of the difference in colorimetric value and the difference in density at corresponding positions, thereby enabling simple and highly accurate evaluation of the fixing state for a variety of images.

[0123] Furthermore, the rubbing member is shaped like a comb with multiple teeth for contacting the recording medium. This allows for more efficient rubbing of all images and simplifies the mechanism for contacting the rubbing member with the recording medium. Furthermore, since it is easy to create rubbed and non-rubbed portions of the image, it is possible to more easily distinguish between evaluation of the fixing state and evaluation of image defects other than the fixing state.

[0124] The portion of the recording medium where the toner fixing state is evaluated is selectively determined based on the image data of the image formed on the recording medium. This allows for selective evaluation of, for example, a high-density portion where toner peeling is likely to occur, thereby further improving the accuracy of the evaluation of the fixing state and shortening the time required for evaluation.

[0125] The means and methods for performing various processes in the image forming system, image forming apparatus, and image inspection apparatus described above can be realized by either dedicated hardware circuits or a programmed computer. The programs may be provided, for example, by a computer-readable recording medium such as a USB memory or a DVD (Digital Versatile Disc)-ROM, or online via a network such as the Internet. In this case, the programs recorded on the computer-readable recording medium are typically transferred and stored in a storage unit such as a hard disk. The programs may also be provided as standalone application software or may be incorporated into the device's software as a function. [Explanation of symbols]

[0126] 1000 imaging system, 100 Image forming device, 110 control section, 120 storage section, 130 Communications Department, 140 Operation display section, 150 image reading unit, 160 Image control unit, 170 Image forming unit, 200 Image inspection equipment, 210 control section, 220 storage section, 230 Communications Department, 240 sliding part, 241 Sliding members, 242 springs, 243 Displacement member, 250 Image reading unit, 251 sensors, 252 photodetector, 300 aftertreatment device, 310 control section, 320 storage section, 330 Communications Department, 340 post-processing section; 341 paper output tray, 342 output tray.

Claims

1. an image forming unit that forms an image using toner on a recording medium; a fixing unit that fixes the image formed on the recording medium onto the recording medium; a reading unit that reads the image fixed on the recording medium with a sensor including a plurality of light receiving elements to generate read image data; a rubbing unit capable of rubbing the image fixed on the recording medium; a control unit that rubs the fixed image with the rubbing unit, reads the rubbed image with the reading unit, and evaluates the fixing state of the toner based on the read image data, The control unit compares the reference image data with the read image data, and if it determines that the position where the difference exceeds a predetermined threshold corresponds to the rubbed position, it evaluates that the toner is not fixed sufficiently, and if it determines that the position where the difference exceeds the threshold does not correspond to the rubbed position, it determines that the image defect has occurred due to a cause other than insufficient toner fixation.

2. an image forming unit that forms an image using toner on a recording medium; a fixing unit that fixes the image formed on the recording medium onto the recording medium; a reading unit that reads the image fixed on the recording medium with a sensor including a plurality of light receiving elements to generate read image data; a rubbing unit capable of rubbing the image fixed on the recording medium; a control unit that rubs the fixed image with the rubbing unit, reads the rubbed image with the reading unit, and evaluates the fixing state of the toner based on the read image data, the rubbing unit has a first mechanism that brings a rubbing member into contact with and separates from the recording medium, and a second mechanism that changes the contact pressure when the rubbing member is brought into contact with the recording medium, An image forming system, wherein the rubbing member has a comb shape having a plurality of teeth for contacting the recording medium.

3. an image forming unit that forms an image using toner on a recording medium; a fixing unit that fixes the image formed on the recording medium onto the recording medium; a reading unit that reads the image fixed on the recording medium with a sensor including a plurality of light receiving elements to generate read image data; a rubbing unit capable of rubbing the image fixed on the recording medium; a control unit that rubs the fixed image with the rubbing unit, reads the rubbed image with the reading unit, and evaluates the fixing state of the toner based on the read image data, The control unit selectively determines a portion on the recording medium where the fixing state of the toner is to be evaluated based on image data of the image to be formed on the recording medium.

4. the reading unit further reads the image on the recording medium that has not been rubbed, and generates the read image data; 4. The image forming system according to claim 1, wherein the control unit further detects waste paper based on the read image data of the image on the recording medium that is not rubbed.

5. the reading unit has a predetermined resolution, 5. The image forming system according to claim 1, wherein the control unit evaluates the fixing state based on the read image data read at the predetermined resolution.

6. 6. The image forming system according to claim 1, wherein the reading unit is a line sensor in which a plurality of the light receiving elements are arranged in a predetermined direction.

7. 7. The image forming system according to claim 6, wherein the predetermined direction is a width direction of the recording medium, and the reading unit reads the image on the recording medium by the light receiving elements arranged in the width direction.

8. 8. The image forming system according to claim 1, wherein the reading section reads the image by detecting the color of the image on the recording medium for each of the light receiving elements.

9. 8. The image forming system according to claim 1, wherein the reading section reads the image by detecting the density of the image on the recording medium for each of the light receiving elements.

10. The image forming system according to any one of claims 1 to 9, wherein the control unit evaluates the fixing state of the toner by comparing the read image data with reference image data generated by reading the recording medium that has not been rubbed after the image has been fixed using the reading unit.

11. The image forming system according to any one of claims 1 to 9, wherein the control unit evaluates the fixing state of the toner by comparing the image data used when forming the image on the recording medium with the read image data as reference image data.

12. 12. The image forming system according to claim 1, wherein the control unit changes a fixing condition of the fixing unit when the control unit determines that the toner has not been fixed sufficiently.

13. 13. The image forming system according to claim 12, wherein the fixing condition is at least one of a fixing temperature, a fixing speed, a fixing pressure, and lighting control of a heater of the fixing unit.

14. The image forming system according to any one of claims 1, 3 to 13, wherein the rubbing unit has a first mechanism that brings a rubbing member into contact with and separates from the recording medium, and a second mechanism that changes the contact pressure when the rubbing member is brought into contact with the recording medium.

15. The image forming system according to claim 14 , wherein a plurality of the rubbing members are arranged in the width direction of the recording medium.

16. The control unit evaluates the fixing state in one of two switchable modes: a first mode for evaluating the fixing state during execution of a print job, and a second mode for evaluating the fixing state before execution of the print job.

17. 16. The image forming system according to claim 1, wherein the control unit evaluates the fixing state during execution of a print job, and discharges the recording medium used for the evaluation as waste paper.

18. 2. The image forming system according to claim 1, wherein the control unit compares the reference image data and the scanned image data based on at least one of a difference in colorimetric value and a difference in density at corresponding positions between the reference image data and the scanned image data.

19. a step (a) of rubbing a toner image formed and fixed on a recording medium with a rubbing unit; (b) reading the rubbed image on the recording medium with a reading unit having a sensor including a plurality of light receiving elements to generate read image data; and (c) evaluating a fixing state of the toner based on the read image data, In step (c), the evaluation program causes a computer to execute a process in which the reference image data and the read image data are compared, and if it is determined that the position where the difference exceeds a predetermined threshold corresponds to the rubbed position, it evaluates that the toner is not fixed sufficiently, and if it is determined that the position where the difference exceeds the threshold does not correspond to the rubbed position, it determines that the image defect has occurred due to a cause other than insufficient toner fixation.

20. a step (a) of rubbing a toner image formed and fixed on a recording medium with a rubbing unit; (b) reading the rubbed image on the recording medium with a reading unit having a sensor including a plurality of light receiving elements to generate read image data; and (c) evaluating a fixing state of the toner based on the read image data, In step (c), an evaluation program is provided for causing a computer to execute a process of selectively determining a portion on the recording medium for evaluating the fixing state of the toner based on image data of the image to be formed on the recording medium.

Images