JP7793965B2 - Image forming system and evaluation program - Google Patents

Description

The present invention relates to an image forming system and an evaluation program.

In an electrophotographic image forming device, 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. The toner image is then transferred to an intermediate transfer member, which then transfers it from the intermediate transfer member to paper. The toner image on the paper is then fixed by applying heat and pressure, forming an image on the paper, etc.

The appropriate 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 by referring to a temperature table that defines fixing temperatures for each of the roughly grouped media, assuming a relatively simple image pattern determined during the development stage. As a result, the fixing state is not always optimal. If the fixing state is not optimal, 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 using a temperature table.

Patent Document 1 below discloses the following prior art: A patch image for fixation evaluation formed on recording paper is fixed at a predetermined fixing temperature, and then a portion of it is rubbed with a rubbing roller. An optical sensor then detects the density of the rubbed and non-rubbed portions of the patch image, and the fixing temperature is optimized by adjusting the fixing temperature so that the density ratio falls within a predetermined reference range. Patent Document 2 below discloses the following prior art: A gray fixation test image is formed on a transfer material, and after fixing, a portion of the fixation test image is rubbed with a pair of rubbing rollers. The densities of the non-rubbed and rubbed portions are then detected with a density sensor that detects density using reflected light, and if 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.

Japanese Patent Application Laid-Open No. 2016-51056 JP 2011-221338 A

However, the above prior art detects the density of the non-rubbed and rubbed areas as the average density of areas 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 a variety of images formed on media. This poses the problem of not being able to optimize fixing conditions for a variety of image and media combinations.

The present invention was made to solve these problems. Specifically, its purpose is to provide an image forming system and evaluation program that can optimize fixing conditions for a variety of image and media combinations.

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

(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.

(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 waste paper based on the read image data of the image on the recording medium that has not been rubbed.

(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.

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

(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.

(6) An 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 light receiving element.

(7) An 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 light receiving element.

(8) An image forming system according to 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, which has not been rubbed after the image has been fixed, using the reading unit.

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

(10) An 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 toner has not been fixed sufficiently.

(11) The image forming system described in (10) above, wherein the fixing conditions are at least one of fixing temperature, fixing speed, fixing pressure, and lighting control of the heater of the fixing unit.

(12) An image forming system according to 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.

(13) The image forming system described in (12) above, wherein the rubbing members are arranged in multiple rows in the width direction of the recording medium.

(14) The image forming system described in any one of (1) to (13) above, wherein the control unit evaluates the fixing state in one of two switchable modes: a first mode in which the fixing state is evaluated during execution of a print job, and a second mode in which the fixing state is evaluated before execution of the print job.

(15) The image forming system described in any one of (1) to (13) above, 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.

(16) The image forming system described in any of (1) to (15) above, wherein the control unit compares the reference image data with the scanned 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.

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

(18) The image forming system described in (12) above, wherein the rubbing member has a comb-like shape with multiple teeth for contacting the recording medium.

(19) The 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.

(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 unit; (b) reading the rubbed image on the recording medium with a reading unit having a sensor including multiple light-receiving elements to generate read image data; and (c) evaluating the fixation state of the toner based on the read image data.

After fixing on the recording medium, the toner fixing state is evaluated based on the read image data generated by reading the rubbed image with multiple light-receiving elements. This allows the fixing conditions to be optimized for a variety of image and media combinations.

FIG. 1 is a schematic diagram illustrating an image forming system. FIG. 2 is a block diagram illustrating a hardware configuration of the image forming apparatus. FIG. 2 is a block diagram showing the hardware configuration of the image inspection device. FIG. 2 is a block diagram showing a hardware configuration of a post-processing device. FIG. 2 is an explanatory diagram showing the configuration of a rubbing unit and an image reading unit of the image inspection device. FIG. 2 is an explanatory diagram showing the configuration of a sensor and a rubbing member. 10A and 10B are explanatory diagrams showing an image of reference image data and a toner image after rubbing; 10 is a flowchart illustrating an example of the operation of the image forming system in creating reference image data. 10 is a flowchart showing another example of the operation of the image forming system in creating reference image data. 10 is a flowchart illustrating an example of the operation of the image forming system. 10 is a flowchart showing another example of the operation of the image forming system.

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that identical elements throughout the drawings will be designated by the same reference numerals, and redundant description will be omitted. Dimensional proportions in the drawings have been exaggerated for the sake of clarity and may differ from the actual proportions. While this embodiment will use "paper" as an example of a recording medium, recording media also includes various films and envelopes. Paper includes paper made from plant-derived mechanical pulp and/or chemical pulp. Paper types (paper grades) include gloss paper (also known as coated paper), matte paper, plain paper, fine paper, and high-gloss paper.

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

(Overall structure)
1, the image forming system 1000 includes an image forming apparatus 100, an image inspection apparatus 200, and a post-processing apparatus 300. 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 along the transport direction of the paper 900.

(Image forming apparatus 100)
The 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 communicatively connected to one another via a bus. The image forming apparatus 100 may be configured as an MFP (Multifunction Peripheral).

The control unit 110 is equipped with a CPU (Central Processing Unit) and various memories, and controls the above-mentioned components and performs various calculation processes according to programs. Furthermore, the control unit 110 can control the components of the image inspection device 200 and the post-processing device 300 through cooperative control with the control unit 210 of the image inspection device 200 and the control unit 310 of the post-processing device 300.

The storage unit 120 is configured using a solid state drive (SDD) or hard disc drive (HDD), and stores various programs and data.

The communication unit 130 is an interface for communication between the image forming apparatus 100 and external devices. Network interfaces conforming to standards such as Ethernet (registered trademark), SATA, and IEEE 1394 are used as the communication unit 130. Various local connection interfaces, such as wireless communication interfaces such as Bluetooth (registered trademark) and IEEE 802.11, are also used as the communication unit 130.

The operation display unit 140 is equipped with a touch panel, numeric keypad, start button, stop button, etc., and is used to display various information and input various instructions.

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 shines light from the light source onto a document set at a predetermined reading position, photoelectrically converts the reflected light using the imaging element, and generates image data from the electrical signal.

The image control unit 160 performs layout processing and rasterization processing on the print data contained in the print job, etc. received by the communication unit 130, and generates image data in bitmap format.

A print job is a general term for print commands sent to the image forming device 100, and includes print data and print settings. Print data is document data to be printed, and can include various types of data, such as image data, vector data, and text data. Specifically, print data can 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 include various settings such as the number of pages, number of copies, paper type, selection of color or monochrome, and page layout.

The image forming unit 170 includes an image creating unit 40, a fixing unit 50, a paper feeding unit 60, and a paper transport unit 70.

The image-forming unit 40 includes imaging units 41Y, 41M, 41C, and 41K, each corresponding to a toner of each color: Y (yellow), M (magenta), C (cyan), and K (black). Each imaging 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 achieved 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 a 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."

The fixing unit 50 includes a heating roller 51, a pressure roller 52, a heater 53, and a temperature sensor 54 (see Figure 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 transported to the fixing nip at the fixing nip, and rotates the heating roller 51 and the pressure roller 52 to melt and fix the toner image 901 on the paper 900 to the surface of the paper 900.

After a toner image 901 is formed and fixed on one side of the paper 900, the paper is transported to the switchback path 73 and turned over, so that a toner image 901 can be formed and fixed on the other side. This allows images to be formed on both sides of the paper 900.

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 made of fluororesin or the like. Multiple halogen lamp heaters 53 are arranged inside the core. Each of the multiple 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 multiple 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 the desired temperature distribution.

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 specified fixing conditions. Furthermore, in the first and second modes described below, which are modes for evaluating the fixing state, 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 onto 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, fixing pressure, and heater 53 lighting control.

The paper feed unit 60 has multiple paper feed trays 61 and 62, and sends out the paper 900 stored in the paper feed trays 61 and 62 one sheet at a time to the downstream paper transport path.

The paper transport unit 70 has multiple 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 multiple 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.

The paper transport unit 70 transports the paper 900 with the image formed on it to a downstream device.

(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.

The configurations of the control unit 210, memory unit 220, and communication unit 230 are the same as those of the image forming device 100, so redundant explanations will be omitted.

The control unit 210 can cooperate with the control unit 110 of the image forming apparatus 100 to control the above-mentioned units and perform various calculation processes, and inspect the toner image 901 on the paper 900. The control unit 210 can also independently control the above-mentioned units and perform various calculation processes, and inspect the toner image 901 on the paper 900.

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

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 this displacement member 243, the rubbing member 241 abuts against the paper 900 and is abutted against the paper 900 with a predetermined contact pressure utilizing 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, while the pair of upper and lower rubbing members 241 are shown at the same position in the transport direction in Figure 5, they may be positioned offset in the transport direction. By using the control unit 210 to move the displacement member 243 in the opposite direction relative to the paper 900, the rubbing member 241 is separated from the paper 900. By adjusting the distance between the displacement member 243 and the paper 900 (more specifically, the transport path of the paper 900), the contact pressure of the rubbing member 241 against the paper 900 can be increased or decreased. The displacement member 243 and spring 242 constitute the first and second mechanisms.

The image inspection device 200 can transport a sheet of paper 900 after a toner image 901 has been formed and fixed on one side of the sheet, which has then been inverted by the switchback path 73 and the toner image 901 has been formed and fixed on the other side. The rubbing members 241 can be positioned on either side of the transport path for the sheet of paper 900, in order to rub the toner images 901 on both the front and back sides of the sheet of paper 900.

The image reading unit 250 includes a sensor 251 that includes multiple light-receiving elements 252 (see Figure 6). The sensor 251 can be, for example, a line sensor in which multiple 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 transport 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's sake, the following description will be given taking the case where the sensor 251 is a line sensor as an example.

Figure 6 is an explanatory diagram showing the configuration of the sensor 251 and the rubbing member 241. In Figure 6, the arrow indicates the transport direction of the paper 900.

In the example shown in FIG. 6 , multiple light-receiving elements 252 of sensor 251, which is a line sensor, are arranged in a row across the width of the paper 900. Multiple light-emitting elements (LEDs) or the like may be arranged beside the light-receiving elements 252 to emit linear light. Additionally, multiple plate-like elements constituting the rubbing member 241 are arranged at positions corresponding to the respective light-receiving elements 252. In this manner, the rubbing member 241 may have an overall comb-like shape with multiple 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 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 sensor 251.

After a toner image 901 is formed and fixed on the paper 900, the image reading unit 250 uses a sensor 251 to read the rubbed toner image 901 and 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 located on both sides of the paper 900 transport path, and read image data for the front and back sides of the paper 900 can be generated.

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.

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.

The scanned image data is used to evaluate the toner fixing state. If the evaluation determines 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.

(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 device 100, so redundant explanations will be omitted.

The control unit 310 cooperates with the control unit 110 of the image forming device 100 to control the above-mentioned units and perform various calculation processes, thereby performing post-processing on the paper 90. The control unit 210 may also independently control the above-mentioned units and perform various calculation processes, thereby performing post-processing on the paper 90.

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

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 undergoing post-processing. Waste paper includes rubbed paper 900 that has been used to evaluate the toner fixation state based on the read image data generated by the image inspection device 200. Waste paper may also 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.

(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 an operation resulting from 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 an independent operation of the control unit 210 of the image inspection apparatus 200.

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 the 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 the 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 is not fixed sufficiently. At this time, the comparison between the reference image data and the scanned image data can be performed for each corresponding pixel.

The control unit 110 can further detect worn paper by determining defects other than the toner fixing state based on the scanned image data of the unabraded toner image 901 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 scanned image data of the unabraded toner image 901 with reference image data. Defects other than the toner fixing state include dirt, etc.

After fixing the toner image 901 to the paper 900, the control unit 110 can generate reference image data by reading the toner image 901 in the image inspection device 200 without rubbing. 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 material).

The control unit 110 may use the image data used when forming a toner image 901 (e.g., an image of a product (printed material)) on the paper 900 to be inspected as the reference image data. In this case, the reference image data may be converted to make the resolution of the reference image data the same as the resolution of the scanned image data.

Figure 7 is an explanatory diagram showing the image of the reference image data and the toner image 901 after rubbing.

Compared to the image of the reference image data, the toner image 901 after rubbing has been scraped off by rubbing. This scraping of the toner image 901 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 if the difference exceeds a predetermined threshold. The toner image 901 may be scraped off in various ways, such as when all layers of the toner image 901 formed by overlapping the three primary color layers (e.g., C, M, and Y layers) of the color toner image 901 are scraped off, as shown in FIG. 7 . Alternatively, the toner image 901 may be scraped off in such a way that only one or two of the top layers of the three primary color layers are scraped off. All 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.

The control unit 110 compares the reference image data with the scanned data, and if it determines that a position (e.g., 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 scanned image data based on at least one of the difference in colorimetric value and the difference in density at corresponding positions (e.g., pixel coordinates).

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 the image defect is due to a cause other than insufficient toner fixation. Positions (portions) in the toner image 901 that are 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 non-rubbed positions in parts of the toner image 901, it is possible to evaluate the toner fixation state in the rubbed portions, and to evaluate image defects other than the toner fixation state in the non-rubbed portions.

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 switchable between each other. This switching can be set by the user for each print job or for all print jobs.

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

The control unit 110 determines (evaluates) the fixing state while the print job is being executed, and ejects the paper 900 used for the determination to the paper output tray 342 as waste paper.

The control unit 110 can selectively determine the portion of the paper 900 where the toner fixing state is to be evaluated, based on the image data of the toner image 901 to be formed on the paper 900. Specifically, the control unit 110 may, for example, selectively determine the portion of 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 where the toner fixing state is to be evaluated may also be the portion where the toner amount exceeds a predetermined threshold. When selectively determining the portion where the toner fixing state is to be evaluated, the rubbing member 241 may be brought into contact only with the portion of the paper 900 that corresponds to the determined portion.

The control unit 110 can change the level of evaluation 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.

Figure 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 device 100 in accordance with a program. This flowchart may also be executed by the control unit 110 of the image forming device 100 and the control unit 210 of the image inspection device 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 device 200 (the same applies to Figures 9 to 11).

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

The control unit 110 reads the toner image 901 on the paper 900 using 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.

The control unit 110 stores the image data generated by scanning in the memory unit 120 as reference image data. Note that the reference image data may also be stored in the memory unit 220 of the image inspection device 200.

Figure 9 is a flowchart showing another example of the operation of the image forming system when creating reference image data.

The control unit 110 stores the product image data in the memory unit 120 as reference image data (S201). The control unit 110 may store the reference image data in the memory unit 220 of the image inspection device 200. As described above, the control unit 110 may convert the reference image data to make the resolution of the reference image data the same as the resolution of the scanned image data.

Figure 10 is a flowchart showing an example of the operation of the image forming system.

Steps S301 to S306 are for adjusting the fixing conditions before production printing (product image formation), and are executed as a second mode for evaluating the fixing status before executing a print job.

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

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).

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

The control unit 110 evaluates the fixation state of the toner image 901 on the paper 900 by comparing the read image data with the reference image data (S304).

If the control unit 110 determines that the fixing is sufficient as a result of evaluating the fixing state (S305: YES), it performs the final printing (product image formation) (S307). Note that by separating the rubbing member 241 from the paper 900 (more specifically, separating it from the transport path of the paper 900) before performing the final printing, the quality of the printed matter is not compromised.

If the control unit 110 determines that the fixing is insufficient (S305: NO), it changes the fixing conditions (S306). The changes to the fixing conditions include at least one of the following: (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 to the fixing conditions include increasing the fixing temperature by 10°C, reducing the fixing speed to 80% of the previous level, and increasing the lighting level 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: The temperature of the heating roller 51 and other components may become uneven in the width direction of the paper 900, 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 heaters of the heater 53 of the fixing unit 50 at the location where the fixing failure is occurring, it is possible to reduce the local fixing failure.

Note that the number of sheets of paper 900 used to evaluate the toner fixing state in steps S301 to S305 is not limited to one, and multiple sheets may be used.

Figure 11 is a flowchart showing another example of the operation of the image forming system.

Steps S401 to S408 are for adjusting the fixing conditions during production printing, and are executed as the first mode for evaluating the fixing status while a print job is being executed.

The control unit 110 determines whether to evaluate the fixing state during execution of the final printing job (S401). For example, the control unit 110 may determine to evaluate the fixing state each 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, 100, or 1,000 sheets, and can be set appropriately through experiments from the perspective of the stability of the fixing state.

If the control unit 110 determines not to evaluate the fixing state (S401: NO), it continues with image formation for the actual printing (S402).

If the control unit 110 determines that the fixing state should be evaluated (S401: YES), it proceeds to step S403 and continues processing.

Steps S403 to S408 are similar to steps S301 to S306 in Figure 10, so their explanation will be omitted.

If the control unit 110 determines that fixing is sufficient after changing the fixing conditions (S407: YES), it resumes image formation for the actual printing (S409).

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

The embodiment provides the following advantages:

After fixing on the recording medium, the toner fixing state is evaluated based on the read image data generated by reading the rubbed image with multiple light-receiving elements. This allows the fixing conditions to be optimized for a variety of image and media combinations.

Furthermore, an image on a recording medium that has not been rubbed is read to generate scanned image data, and waste paper is detected based on the scanned image data of the image that has not been rubbed. This allows the image reading means to be used for both evaluating the toner fixation state and evaluating things other than the toner fixation state, thereby reducing the size of the device and shortening the inspection time.

Furthermore, the scanned image data is read at a specified resolution, and the fixing state is evaluated based on the scanned image data at the specified resolution. This allows for highly accurate evaluation of the fixing state for a variety of images.

Furthermore, the image is read 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 parameters. The benefits of using a relatively high-resolution line sensor compared to using a densitometer to read images are described below in detail. When evaluating density differences, the test image requires a certain area size, limiting the 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 contains areas with a high toner amount locally on the surface of the paper 900, the fixing temperature in those areas will be set lower than the appropriate value. Furthermore, when evaluating density differences, the accuracy of detecting the fixation state can be reduced 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 adjusted properly. However, the densitometer may measure a density value above a predetermined threshold due to the influence of the toner in the lower layer, resulting in an erroneous assessment that the toner is sufficiently fixed. These problems can be overcome by reading the image with a relatively high-resolution line sensor in which multiple light-receiving elements are arranged in a specific direction.

In addition, the arrangement direction of the light-receiving elements of the sign sensor is the width direction of the recording medium. This makes it possible to more simply and efficiently improve the accuracy of evaluation of the fixing state, etc.

In addition, 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 relatively 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 primary color toner layers, peeling off of only the upper layer can be detected with high accuracy.

In addition, the image is read by detecting the density of the image on the recording medium for each light-receiving element. This allows for highly accurate evaluation of the fixing state, etc., using a simple device.

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 reference images.

Furthermore, the image data used when forming an image on a recording medium is set as reference image data. This makes it easier to generate a reference image.

Furthermore, if the toner is judged to have not been fixed sufficiently, the fixing conditions of the fixing unit are changed. This effectively reduces the occurrence of waste paper due to poor fixing.

Furthermore, the fixing conditions are set to at least one of the fixing temperature, fixing speed, fixing pressure, and heater on/off control of the fixing unit. This makes it possible to simply and effectively prevent paper waste due to insufficient fixing.

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. This makes it possible to evaluate the fixing state, etc., with a simpler configuration.

Furthermore, multiple rubbing members are arranged in the width direction of the recording medium. This allows for effective and easy rubbing across a wide area of the recording medium surface.

Furthermore, the fixing state is evaluated in either of two switchable modes: a first mode, which evaluates the fixing state while a print job is being executed, or a second mode, which evaluates the fixing state before a print job is executed. This allows for more flexible evaluation of the fixing state, etc.

The fixing state is evaluated while the print job is running, 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.

Furthermore, the reference image data is compared with the scanned image data, and if it is determined that the position where the difference exceeds a predetermined threshold corresponds to the rubbed position, it is evaluated as having insufficient toner fixing. 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 due to 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.

Furthermore, the reference image data and scanned image data are compared based on at least one of the differences in colorimetric values and the differences in density at corresponding positions. This allows for easy and highly accurate evaluation of the fixing state for a variety of images.

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 areas of the image that are rubbed and areas that are not rubbed, it is easier to distinguish between evaluation of the fixing state and evaluation of image defects other than the fixing state.

Based on the image data of the image formed on the recording medium, the areas on the recording medium where the toner fixing state is evaluated are selectively determined. This allows for selective evaluation of areas with high density where toner is likely to peel off, for example, further improving the accuracy of the fixing state evaluation and shortening the time required for evaluation.

The means and methods for performing the various processes in the image forming system, image forming device, and image inspection device described above can be implemented using either dedicated hardware circuits or programmed computers. The programs may be provided, for example, on computer-readable recording media such as USB memory or 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 media are typically transferred to 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.

1000 Image forming system,
100 Image forming apparatus,
110 control unit,
120 storage unit,
130 Communications Department,
140 operation display section,
150 image reading unit,
160 Image control unit,
170 Image forming unit,
200 Image inspection device,
210 control unit,
220 storage unit,
230 Communications Department,
240 sliding part,
241 sliding member,
242 springs,
243 displacement member,
250 image reading unit,
251 sensors,
252 light receiving element,
300 post-treatment device,
310 control unit,
320 storage unit,
330 Communications Department,
340 post-processing unit,
341 paper output tray,
342 Paper output tray.

Claims (20)

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 . 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 . 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 . the reading unit further reads the image on the recording medium that has not been rubbed, and generates the read image data;
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. the reading unit has a predetermined resolution,
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. 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. 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. The image forming system according to claim 1 , 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. 8. The image forming system according to claim 1 , 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. 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. 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 image data used when forming the image on the recording medium as reference image data. 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. 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. The image forming system of any one of claims 1, 3 to 13, 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. 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. The image forming system according to any one of claims 1 to 15, wherein the control unit evaluates the fixing state in either a first mode in which the fixing state is evaluated during execution of a print job, or a second mode in which the fixing state is evaluated before execution of the print job, which are switchable between the first mode and the second mode. 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. 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. 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 . 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 .