JP6948779B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

In an image forming apparatus that heat-fixes a toner image formed by an electrophotographic method on a recording paper to form an image, the fixing temperature of the fuser is set according to the amount of color material (toner amount) per unit area placed on the recording paper. decide. Normally, the maximum amount of color material that can be placed per unit area of the recording paper is determined in advance, and the temperature of the fuser is controlled so that the transferred image can be reliably fixed with the maximum amount of color material. In addition to this, various methods of analyzing image data and controlling the fixing temperature according to the image data have also been proposed. For example, Patent Document 1 describes a method of finely controlling the fixing temperature according to the area of a portion of a toner on which a predetermined amount or more is applied. Further, in Patent Document 2, the characteristics of an image (many characters, graphs, halftones, and high density parts) are obtained from the relationship between the distribution rate of each pixel density and the area of the image, and the fixing temperature is determined according to the characteristics. How to adjust is described. On the other hand, if the fuser cannot be operated at an appropriate temperature with respect to the amount of toner loaded, hot offset and cold offset occur, and the fuser is soiled with the offset toner. Therefore, Patent Document 3 describes a method for cleaning a fuser, in which a blank sheet of paper is passed through to clean the fuser, and the blank sheet is adhered with dirt to be cleaned.

Japanese Unexamined Patent Publication No. 2014-074894 Japanese Unexamined Patent Publication No. 2000-221831 Japanese Unexamined Patent Publication No. 2000-47509

However, in the method of controlling the fuser at a fixing temperature suitable for a high loading amount portion on which a predetermined amount or more of toner is loaded as in Patent Document 1, fixing suitable for a low loading amount portion having a small toner loading amount. Cannot be controlled by temperature. For this reason, there is a possibility that an excessive amount of heat may occur in the low loading amount portion and the fixability may be deteriorated. In the low loading amount (toner loading amount is less than about 70%), the halftone dot density is low in the local region, so that the contact surface between the heating roller and the paper increases, and the water content of the paper evaporates during fixing to reduce the amount of heat. I will take it away. At this time, in an environment where the water content of the paper is high, the amount of heat taken away when the water evaporates is large, so that the amount of heat required for melting the toner cannot be obtained, and the density on the page surface may become uneven, causing image defects. ..

On the contrary, in an environment where the water content of the paper is low, the amount of heat taken away when the water is evaporated is small, so that the amount of heat controlled in the high loading amount portion is excessive for the low loading amount portion.

Further, in the method of controlling the fixing temperature by roughly analyzing the characteristics of the image data to be printed in Patent Document 2, a low loading amount portion (toner loading amount is less than about 70%) in which an area where image defects are conspicuous is large is formed. It is not controlled by accurately determining whether or not it exists. For this reason, the temperature of the fuser is raised more than necessary, and it becomes impossible to suppress the amount of heat that was to be reduced by controlling the temperature according to the high loading amount portion or using the low melting point toner.

An object of the present invention is to solve the above-mentioned problems of the prior art.

An object of the present invention is to provide a technique for reducing the occurrence of image defects by controlling the temperature of a fuser at the time of fixing a recording paper including a loading amount region in which the toner loading amount is less than a predetermined value. It is in.

In order to achieve the above object, the image forming apparatus according to one aspect of the present invention has the following configuration. That is,
An image forming apparatus that forms an image in an electrophotographic process.
A receiver that receives image data and
An image forming means for forming a toner image on a recording paper based on the image data received by the receiving unit, and an image forming means.
A fuser that heat-fixes the toner image formed by the image forming means to the recording paper, and
It has a temperature control means for setting a fixing temperature at the time of heat fixing by the fixing device and controlling the temperature of the fixing device so as to reach the set fixing temperature.
The temperature control means
By analyzing the image data received by the receiving unit, the first loading amount region in which the toner loading amount per unit area transferred to the recording paper is within the range from the first threshold value to the second threshold value. Then, a process is performed to detect a second loading amount region in which the toner loading amount per unit area transferred to the recording paper exceeds the third threshold value.
When said mixed first applied amount region and the second bearing amount region is detected, the mixing of the first toner amount region and the second bearing amount region is not detected and the first The fixing temperature of the fuser is set to a higher temperature than when the loading area is not detected, the third threshold value is larger than the second threshold value, and the detected area of the first loading area is , The second loading area is larger than the detected area.

According to the present invention, there is an effect that good image quality can be maintained by controlling the temperature of the fuser at the time of fixing the recording paper including the loading amount region in which the toner loading amount is smaller than a predetermined value.

Other features and advantages of the present invention will become apparent in the following description with reference to the accompanying drawings. In the attached drawings, the same or similar configurations are given the same reference numbers.

The accompanying drawings are included in the specification and are used to form a part thereof, show an embodiment of the present invention, and explain the principle of the present invention together with the description thereof.
The figure explaining the structure of the system including the image forming apparatus which concerns on Embodiment 1. FIG. The block diagram explaining the structure of the image forming apparatus which concerns on Embodiment 1. FIG. FIG. 3 is a block diagram illustrating a functional configuration of an image processing unit of the image forming apparatus according to the first embodiment. The flowchart explaining the image processing by the image processing unit which concerns on Embodiment 1. The figure which shows an example of the function setting screen displayed in the UI part of the image forming apparatus which concerns on Embodiment 1. FIG. The flowchart explaining the processing by the image forming apparatus which concerns on Embodiment 1. FIG. 5 is a flowchart illustrating an image analysis process by an image analysis unit of the image forming apparatus according to the first embodiment. FIG. 5 is a flowchart illustrating a process of calculating the toner loading amount (TnrSum) in a local region unit in S701 of FIG. 7. In the flowchart of FIG. 7, a diagram illustrating an outline of a process for obtaining an area of a low loading region continuous in the sub-scanning direction and the main scanning direction. The figure which shows an example of each of the gradation correction table, the halftone dot ratio table, and the toner loading amount conversion table which concerns on Embodiment 1. FIG. The figure explaining the relationship between the toner loading amount, the fixing temperature control, and the cleaning control which concerns on Embodiment 1. FIG. The flowchart explaining the fixing temperature control of S601 of FIG. 6 by the image forming apparatus which concerns on Embodiment 1. FIG. The flowchart explaining the cleaning control of S603 of FIG. 6 by the image forming apparatus which concerns on Embodiment 1. FIG. The figure explaining the relationship between the amount of toner loading which concerns on Embodiment 2, the temperature control of a fuser, and the frequency of a cleaning request. The figure explaining the relationship between the toner loading amount and the water content of paper at the time of controlling the temperature of the fixing device with respect to the high loading part with a large toner loading amount. The flowchart explaining the fixing temperature control of S601 of FIG. 6 by the image forming apparatus which concerns on Embodiment 2. The flowchart explaining the cleaning control of S603 of FIG. 6 by the image forming apparatus which concerns on Embodiment 2. FIG. 5 is a flowchart illustrating an image analysis process by an image analysis unit of the image forming apparatus according to the third embodiment. FIG. 3 is a diagram illustrating an outline of a process for obtaining a low loading area according to the flowchart of FIG. 18 in the third embodiment. FIG. 5 is a flowchart illustrating a modification of the image analysis process of FIG. 18 by the image analysis unit of the image forming apparatus according to the third embodiment. The figure which shows two low loading part divided into the perimeter of a fuser. FIG. 5 is a flowchart illustrating an image analysis process by an image analysis unit of the image forming apparatus according to the fourth embodiment. The flowchart explaining the process of S2201 of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the present invention according to the claims, and not all combinations of features described in the present embodiment are essential for the means for solving the present invention. ..

In the embodiment described below, an image forming apparatus that detects whether or not there is a low loading portion having an area equal to or larger than a predetermined area based on the image data and controls the temperature control and cleaning of the fuser will be described. ..

[Embodiment 1]
FIG. 1 is a diagram illustrating a configuration of a system including an image forming apparatus 101 according to a first embodiment of the present invention.

The image forming apparatus 101 forms an image by an electrophotographic process, for example, as will be described later with reference to FIG. Further, the image forming apparatus 101 detects whether or not there is a low loading portion having an area equal to or larger than a predetermined area from the input image data to be formed, and based on the detection result, cleaning control and temperature control of the fuser. Take control. Here, the fuser fixes the unfixed toner image on the paper. Here, as described above, the low loading amount portion is, for example, a region where the loading amount of toner (transfer agent) is less than about 70%. The image forming apparatus 101 receives and prints image data from a host computer 102, a mobile terminal 103, a server 104, another image processing apparatus (not shown), or the like via the network 105 (image forming) (including FAX reception printing). To execute. Further, the image data obtained by scanning the original by the image reading device (scanner) attached to the image forming device 101 can be transmitted to the host computer 102, the mobile terminal 103, and the server 104 via the network 105. Further, the copy operation can be realized by printing the image data obtained by reading the image data by using the printing unit attached to the image processing device 101.

In the following description, an example will be described in which it is detected from the image data whether or not there is a low loading portion having an area equal to or larger than a predetermined area, and the temperature control and cleaning control of the fuser are performed based on the detection result. However, the present invention is not limited to such a configuration, and detection of a low loading portion having an area equal to or larger than a predetermined area, instructions to an image forming apparatus for cleaning / fixing temperature control, and the like are sources of image data. It may be executed by the host computer 102 or the like. Alternatively, this process may be distributed in cooperation with the image forming apparatus 101 and the host computer 102, the mobile terminal 103, the server 104, etc., which are the sources of the image data.

Next, the configuration of the image forming apparatus 101 will be described.

FIG. 2 is a block diagram illustrating the configuration of the image forming apparatus 101 according to the first embodiment.

The image forming apparatus 101 includes a data input unit (reception unit) 201, an image reading unit 202, a control unit 203, a storage unit 204, a UI unit 205, a printing unit 206, an image processing unit 207, a fixing temperature control unit 208, and cleaning control. It has a part 209. The data input unit 201 receives and inputs print data transmitted from, for example, the server 104 via the network 105. The image reading unit 202 has a scanner, reads an image of a document, and outputs the image data. The control unit 203 controls the operation of the image forming apparatus 101, and has a CPU 210, a ROM 211, and a RAM 212. The CPU 210 executes a program stored in the ROM 211 to execute the processes shown in the flowcharts described later. The storage unit 204 can store a large amount of data such as a hard disk drive (HDD). The CPU 210 may be configured to expand the program stored in the storage unit 204 into the RAM 212 and execute a process described later. The UI unit 205 includes an operation panel and a display unit, displays a message to the user, and receives an operation instruction by the user. The UI unit 205 may have a touch panel function. The printing unit 206 is a printer engine, in which an image is formed on paper by an electrophotographic method.

The image processing unit 207 detects from the image data whether or not there is a low loading portion having an area equal to or larger than a predetermined area. Then, in response to the detection result from the image processing unit 207, the fixing temperature control unit 208 controls the temperature control of the fixing device of the printing unit 206. Further, the cleaning control unit 209 controls the frequency of the cleaning request in response to the detection result from the image processing unit 207, and issues the cleaning request to the UI unit 205 or the printing unit 206. The cleaning control here is characterized in that the frequency of cleaning requests is controlled, and does not limit the display contents on the UI unit 205 and the cleaning method of the printing unit 206. The environment sensor 213 is a sensor that detects temperature and humidity, and detects the state of the environment in which the image forming apparatus 101 is installed.

Here, the image processing unit 207, the fixing temperature control unit 208, and the cleaning control unit 209 are not processing units such as specialized hardware, but the functions are realized by, for example, the CPU 210 executing the above-mentioned program. It may be configured to be used.

Next, the function settings at the time of printing will be described.

FIG. 5 is a diagram showing an example of a function setting screen displayed on the UI unit 205 of the image forming apparatus 101 according to the first embodiment.

In the item list 502, setting items of functions that can be specified as options and a list of current setting contents are displayed. Then, the item selected in the item list 502 (here, "halftone" is selected) is displayed in the selection item 503, and the setting content can be changed. In the function that can set the details, the detail button 504 is displayed, and by pressing the detail button 504, the details can be set from the detailed setting window of each function (not shown) that is activated and displayed.

When the high-saturation printing mode 506 is selected in the item list 502, the toner loading limit per unit area can be changed, and the high-saturation image can be printed with higher saturation. As shown in FIG. 5, when the high-saturation printing mode 506 is set to “not used”, the toner loading amount is limited to 200% in consideration of energy saving, running cost, productivity, and the like. When the high-saturation printing mode 506 is set to "use", the amount of toner applied can be increased up to 230% by increasing the amount of heat of the fuser, so that a high-saturation image can be printed with higher saturation.

In FIG. 5, halftone 505 is selected in the item list 502. In this case, the image forming method is performed according to the attribute signal (Text, Graphics, Image, etc.) of the object generated from the information described in PDL. You can change the pattern. The default setting is "Pattern 2" as shown in the figure. In this "Pattern 2", a high number of lines (around 200 lines) is assigned to the Text attribute where detailed reproduction is important, and a low number of lines (around 150 lines) is assigned to the Graphics / Image attribute where stable dot reproduction is important. Then, by changing the setting of this pattern to another pattern, the combination of the number of lines assigned to each attribute can be changed, the number of lines of all attributes can be made uniform, and the error diffusion process can be assigned.

When gray compensation 507 is selected in the item list 502, an attribute for performing gray compensation can be specified. In the example of FIG. 5, the attribute for performing gray compensation is set to "text only". The gray compensation is a function of printing a color image signal value (a signal value of RGB equal amount or its vicinity) that looks gray on a display in a single black color.

Next, when the image forming apparatus 101 according to the first embodiment forms (prints) an image using the printing unit 206, the image processing unit 207 performs image processing on the image data included in the input print data. The configuration will be described.

FIG. 3 is a block diagram illustrating the functional configuration of the image processing unit 207 of the image forming apparatus 101 according to the first embodiment. As described above, the function of the image processing unit 207 may be realized by hardware, or may be realized by the CPU 210 executing a program.

The image processing unit 207 includes an input unit 301, a color conversion processing unit 302, a rendering processing unit 303, a gradation correction processing unit 304, an image forming processing unit 305, an output unit 306, and an image analysis unit 307. The input unit 301 receives, for example, image data described in PDL (page description language) included in the print data input by the data input unit 201. The color conversion processing unit 302 performs color conversion from RGB to YMCK, for example. The rendering processing unit 303 renders the PDL data and converts it into image data. The gradation correction processing unit 304 corrects the gradation of the image data. The image forming processing unit 305 creates information of each color necessary for image forming from the converted image data. The image analysis unit 307 analyzes the CMYK data after the image formation process to detect a low loading portion having an area equal to or larger than a predetermined value.

Next, the process of detecting the low loading portion of the image from the image data by the image analysis unit 307 will be described.

FIG. 4 is a flowchart illustrating image processing by the image processing unit 207 according to the first embodiment. Here, an example will be described in which the CPU 210 of the control unit 203 controls each unit of the image processing unit 207 according to a program.

First, in S401, the CPU 201 outputs the document data for print output received by the data input unit 201 to the input unit 301 of the image processing unit 207. Next, the process proceeds to S402, and the rendering processing unit 303 converts the input document data into raster image data, and supplies the image data to the color conversion processing unit 302 to execute the color conversion processing. At this time, the CPU 210 controls the rendering processing unit 303 to determine the characteristics (characters, figures, photographs, etc.) of each pixel from the PDL data. Then, attribute data such as Text, Graphics, Image, SmallText, ThinLine, etc. are generated. Then, the generated attribute data is passed to the color conversion processing unit 302. Next, proceeding to S403, the CPU 210 color-converts the RGB data generated by the color conversion processing unit 302 into CMYK data to generate raster image data, and passes it to the gradation correction processing unit 304. Further, the CPU 210 also passes the attribute data received from the color conversion processing unit 302 to the gradation correction processing unit 304 to execute the gradation correction processing.

In the color conversion from RGB data to CMYK data, the printing unit 206 converts so as not to exceed the maximum amount of toner that can be printed (for example, 200%). For example, when the high-saturation printing mode of the item list 502 in FIG. 5 is set to "use", the maximum loading amount can be up to 230%. Further, the CPU 210 converts RGB data into CMYK data while switching the presence / absence of gray compensation according to the attribute data received from the color conversion processing unit 302 and the gray compensation setting of the item list 502.

In this way, in S403, the CPU 210 controls the gradation correction processing unit 304 to perform gradation correction processing on the CMYK data in consideration of the gradation characteristics of the printing unit 206 of the image forming apparatus 101, and the processed image data. Is passed to the image forming processing unit 305. Further, the CPU 210 controls the gradation correction processing unit 304 so that the attribute data is also passed to the image forming processing unit 305.

Since the gradation characteristics of the printing unit 206 vary depending on the image forming method, it is necessary to switch the gradation correction processing according to the image forming method. Therefore, the CPU 210 shall perform the gradation correction processing according to the attribute data received by the gradation correction processing unit 304 and the setting of the halftone of the item list 502.

Next, proceeding to S404, the CPU 210 controls the image forming processing unit 305 to perform processing such as error diffusion processing and screen processing on the CMYK data after gradation correction, and passes the data to the output unit 306 and the image analysis unit 307. .. Next, in S405, the CPU 210 controls the image analysis unit 307 to analyze the CMYK data after the above-mentioned processing, and performs detection processing of a low loading portion having an area equal to or larger than a predetermined area. Then, the detection result is transmitted to the fixing temperature control unit 208 and the cleaning control unit 209. The details of the image analysis process at this time and the fixing temperature control and cleaning control using the results will be described later. Then, the CPU 210 controls the output unit 306 to output the CMYK data processed for image formation to the printing unit 206 for printing.

FIG. 6 is a flowchart illustrating processing by the image forming apparatus 101 according to the first embodiment. This process is achieved by the CPU 210 expanding the program stored in the storage unit 204 into the RAM 212 and executing the program.

First, in S601, the CPU 210 receives the analysis result of the image data from the image analysis unit 307, controls the fixing temperature control unit 208 using the information of the analysis result, and determines the temperature of the fixing device in page units (paper units). Control. Next, the process proceeds to S602, and the CPU 210 receives the CMYK data for image formation output from the output unit 306 of the image processing unit 207, controls the printing unit 206 based on the CMYK data, and responds to the analysis result of S601. Fixing is performed at the temperature of the fuser and printing is performed. Next, proceeding to S603, the CPU 210 receives the analysis result of the image data from the image analysis unit 307, and controls the frequency of the cleaning request to the cleaning control unit 209 according to the information of the analysis result. Further, a cleaning request is issued to the UI unit 205 or the printing unit 206 as needed, and this process is terminated.

Next, with reference to FIGS. 7 to 9, the image analysis unit 307 analyzes the CMYK data processed for image formation in S405 of FIG. 4, and obtains a low loading portion having an area equal to or larger than a predetermined value. The analysis process to be detected will be described. Here, as an example, a portion where the local toner loading amount is 10 to about 70% is defined as a low loading amount portion, and a region whose area is equal to or larger than a predetermined size, for example, 10 mm × 10 mm or more is detected as a low loading amount region.

FIG. 7 is a flowchart illustrating an image analysis process by the image analysis unit 307 of the image forming apparatus 101 according to the first embodiment. Here, it is assumed that the CPU 210 expands the program stored in the storage unit 204 into the RAM 212 and executes the expanded program to realize the process shown in this flowchart.

First, in S701, the CPU 210 analyzes the CMYK data after the image formation process received in S405 of FIG. 4 to calculate the loading amount (TnrSum) in the local region unit. Since the effect of evaporation of water contained in the recording paper on the fixability is determined by the amount of toner loaded in this local region, the calculation of the amount of toner loaded has the same resolution as the image forming process, or It shall be performed at a high resolution of 600 dpi or more. Details of this process will be described later with reference to FIG.

Next, the process proceeds to S702, and the CPU 210 determines whether or not the toner loading amount (TnrSum) in the local region calculated in S701 is within the threshold range specified in advance. Here, if it is determined that the value is within the threshold range, PickupTnrArea = 1, and if it is not within the threshold range, PickupTnrArea = 0.

Here, as an example of the threshold range specified in advance, 10% <TnrSum <70% is set, but the present invention is not limited to this. Within the toner loading range (about 0% to 70%) where the contact surface between the roller of the fuser and the recording paper becomes large, the threshold range is set in consideration of the fact that density unevenness is easily noticeable due to the decrease in fixability. do. Alternatively, the threshold range may be set in consideration of the amount of toner loaded, which may cause stains on the fuser due to offset toner.

Next, proceeding to S703, the CPU 210 counts the amount yRun (main scanning position) of lines in which the local region where PickupTnrArea = 1 is continuous in the sub-scanning direction at the main scanning position N. Since the size of the image quality defect that is conspicuous in the low loading amount portion is a size exceeding millimeters, for example, when the image resolution is 600 dpi, the main scanning position and the sub-scanning direction are roughened, for example, in units of 100 dpi. You may sample and count the number of consecutive lines. Here, the initial value of N is "1", and here, the continuous amount in the sub-scanning direction of the local region at each main scanning position is obtained until the value of N becomes the maximum number of pixels in the main scanning direction. However, as described above, since the size in which the image quality is conspicuously deteriorated in the low loading amount portion is a size exceeding a millimeter, a continuous amount may be counted by coarsely sampling, for example, in units of 100 dpi. In this way, the number of consecutive lines of a plurality of pixel blocks is obtained.

Next, the process proceeds to S704, and the CPU 210 determines the continuous amount yRun from the number of continuous lines of the plurality of pixel blocks. That is, it is determined whether or not the continuous amount yRun (main scanning position) exceeds the threshold value yRunThre (= 10 mm) specified in advance. Here, if there is a continuous amount yRun exceeding the threshold value at this main scanning position, the process proceeds to S705, and the CPU 210 proceeds to S706 with yRunThreOver (main scanning position) = 1. The initial value of this yRunThreOver (main scanning position) is set to "0".

When it is determined that the processing in the main scanning direction is completed, the process proceeds to S706, and the CPU 210 obtains the continuous amount in the main scanning direction of the region where yRunThreOver (main scanning position) = 1 as a result of determining the continuous amount in the sub-scanning direction. Here, the continuous amount xRun in which the continuous region in the sub-scanning direction in which yRunThreOver (main scanning position) = 1 is continuous in the main scanning direction is counted. Since the size at which the image quality is conspicuously deteriorated in the low loading amount portion is defined by a size exceeding millimeters, a continuous amount may be obtained by roughly sampling in the main scanning direction, for example, in units of 100 dpi.

Next, the process proceeds to S707, and the CPU 210 determines whether or not any of the continuous amounts xRun in the main scanning direction exceeds the predetermined threshold value xRunThre (= 10 mm). If it is determined that there is a continuous amount in the main scanning direction that exceeds the threshold value, the process proceeds to S708, and xRunThreOver = 1 to proceed to S709. The initial value of this xRunThreOver is set to "0". Next, the process proceeds to S709, and the CPU 210 stores in the RAM 212 that the page includes a low loading portion having an area of a predetermined value or more based on the result detected in the above processing, and ends this processing. When the continuous amount of a plurality of blocks is obtained in S703 and S706, whether or not the maximum amount of the continuous amount of the plurality of blocks exceeds the threshold value in the corresponding S704 and S707, or the continuous amount of the plurality of blocks is obtained. It may be determined whether at least one of the quantities exceeds the threshold. Alternatively, the number of blocks exceeding the threshold value, the continuous amount of the maximum block, etc. are recorded, and in S709, they are stored as the feature amount of the page and used for the temperature control of the subsequent fuser. You may.

In this way, it is possible to detect a low loading portion having a processing area. As a result, in the subsequent image forming process, when the paper printed with the image data of the page is fixed, it can be determined whether or not the page includes a low loading portion of a predetermined area or more.

FIG. 9 is a diagram illustrating an outline of a process for obtaining an area of a low loading region continuous in the sub-scanning direction and the main scanning direction in the flowchart of FIG. 7.

A portion where the toner loading amount in the local region falls within a predetermined low loading amount region (for example, 10% <total CYMK amount <70%) is determined (901). Then, the portion divides the main scanning position and obtains a continuous amount continuous in the sub-scanning direction (902). Then, for the portion (903) in which the continuous amount in the sub-scanning direction exceeds the threshold value (for example, 10 mm), the continuous amount continuous in the main scanning direction is obtained (904). Then, it is determined whether or not the page has a portion where the continuous amount continuous in the main scanning direction is equal to or more than a threshold value (for example, 10 mm) (905). Then, if there is such a continuous portion, the area of the region is obtained, and the temperature of the fuser is controlled according to the area.

By the process described above, the area is measured from the continuous amount in the sub-scanning direction of the low loading amount portion and the continuous amount in the main scanning direction, and the low loading on the page is less than a predetermined area where there is a great concern that the fixability is deteriorated. It can be determined whether the area of quantity exists. If offset toner is continuously generated at the same main scanning position, dirt tends to concentrate. Therefore, in the first embodiment, the continuous amount in the sub-scanning direction is emphasized, and the continuous amount in the main scanning direction is obtained for the portion where the continuous amount in the sub-scanning direction is equal to or larger than the threshold value. However, the present invention is not limited to this. In short, it is sufficient if it is possible to detect whether or not the area of the low loading portion is equal to or larger than a predetermined value in the page.

Further, in the first embodiment, the image data is analyzed on a page-by-page basis. However, the present invention is not limited to this, and when printing a plurality of copies, the analysis result of one copy is temporarily stored in the storage unit 204, and when printing repeatedly, the image data is analyzed for each page. The analysis result stored in the storage unit 204 may be used without performing the analysis.

Further, in the first embodiment, the threshold value of the continuous amount in the sub-scanning direction and the continuous amount in the main scanning direction is set to 10 mm, but the present invention is not limited to this. Further, independent threshold values may be set for the main scanning direction and the sub-scanning direction. Further, it is sufficient to specify a size in which uneven density is easily noticeable, or a size in which offset toner is continuously generated at the same main scanning position and dirt is concentrated and easily accumulated.

Further, in the first embodiment, the image analysis processing is not performed separately for the density unevenness due to insufficient heat and the stain due to offset toner due to excessive heat. However, the threshold value may be set and determined according to the intended use. Alternatively, as shown in FIG. 15, since the amount of heat for the toner changes according to the environmental conditions, the high temperature / high humidity environment and other areas are discriminated from the environmental information received from the environmental sensor 213, and the area is correspondingly determined. You may switch the size threshold.

For example, as an example of this threshold value, if the continuous amount in the sub-scanning direction is large at the same main scanning position, dirt tends to accumulate. Therefore, it may be 10 mm × 100 mm for cleaning, or when limited to a high temperature / high humidity environment. , 5 mm × 5 mm or the like may be used with an emphasis on density unevenness.

FIG. 15 is a diagram illustrating the relationship between the toner loading amount and the water content of the paper when the temperature of the fixing device is controlled for the high loading portion where the toner loading amount is large.

The circles indicate that there is no problem with this temperature control. In the high-loading portion where the amount of toner loaded is large, the contact surface between the roller of the fuser and the paper is small. Therefore, since the moisture of the paper does not escape to the surface of the paper, the heat is not easily taken away. Therefore, no problem occurs regardless of the water content of the paper even when the temperature and humidity are high or not.

On the other hand, in the low loading amount portion where the toner loading amount is small, the contact surface between the roller of the fuser and the paper becomes large, so that the environment and the water content of the paper are greatly affected.

For example, in the case of 1501 in FIG. 15, the amount of toner loaded is small and the amount of water in the paper is small, so that the amount of heat is excessive, and hot offset occurs in the low loading amount portion to stain the fixing film. Further, in the case of 1502, the amount of heat applied is small and the amount of water in the paper is large, so that the amount of heat is insufficient. That is, since the amount of heat is taken away by the evaporation of a large amount of water contained in the paper, the amount of heat supplied to the toner is insufficient.

FIG. 8 is a flowchart illustrating a process of calculating the toner loading amount (TnrSum) in the local region unit in S701 of FIG. 7.

In the first embodiment, since the image analysis is performed in S405 of FIG. 4, the CMYK data (each color loading amount information) after the color conversion is subjected to the gradation correction processing and the image formation processing, and the area gradation is obtained. The image is represented. Therefore, the halftone dot ratio per unit area is analyzed, and the amount of toner loaded is calculated back from that.

First, in S801, the CPU 210 calculates the amount of load in the local region from the CMYK data after the image formation process received by the image analysis unit 307 in S405 of FIG. 4, so that the image data is stored in a predetermined region unit corresponding to the local region. Cut out. Next, the process proceeds to S802, and the CPU 210 counts the number of pixels included in the image data existing in the area. Next, the process proceeds to S803, and the CPU 210 obtains the halftone dot ratio from the number of pixels with respect to the area of the area. That is, the halftone dot ratio is calculated assuming that the area is filled with a solid solid color as 100%. Next, the process proceeds to S804, and the CPU 210 generates a table that is inversely converted into the toner loading amount from the halftone dot ratio obtained in S803, and calculates the toner loading amount from the halftone dot ratio. By executing the processes S801 to S804 on each of the CMYK data in this way, the amount of toner loaded on each of the CMYK data is calculated. Then, the process proceeds to S805, and the CPU 210 calculates the total amount of toner corresponding to the CMYK data in the local region (see FIG. 9) from the amount of toner loaded in the CMYK data obtained in S804, and ends this process.

FIG. 10 is a diagram showing an example of each of the gradation correction table, the halftone dot ratio table, and the toner loading amount conversion table according to the first embodiment.

FIG. 10A shows an example of a gradation correction table, which is a table used in the gradation correction processing of S403 in FIG. 4, and is the floor of the printing unit 206 that varies depending on the environment, durability, machine body variation, and the like. The tonal characteristics are corrected.

FIG. 10B shows an example of the halftone dot ratio table, and the input multi-value signal and the unit area in the conversion from the multi-value (10-bit) gradation expression to the area gradation by the image formation process of S404 in FIG. The relationship between the halftone dot ratios is shown. In FIG. 10B, the halftone dot ratios corresponding to the multi-valued signals of each color have a substantially linear relationship.

FIG. 10C shows an example of a toner loading amount conversion table, which is a table for calculating the toner loading amount from the halftone dot ratio.

Since the halftone dot ratio can be obtained by multiplying the gradation correction table and the halftone dot ratio table with respect to the amount of toner loaded, the gradation correction table and the halftone dot ratio table can be combined and the inverse conversion thereof can be obtained. , It is possible to generate a table for obtaining the amount of toner loaded from the halftone dot ratio.

As described above, the amount of toner loaded in each local region can be calculated. In the first embodiment, the image analysis process of S405 in FIG. 4 is described as being performed after the image formation process of S404 in FIG. 4, but the present invention is not limited thereto. For example, the image analysis process of S405 may be performed after the color conversion process of S402 of FIG. In that case, since the image signal of the CMYK data after color conversion is the toner loading amount information, it is not necessary to back-calculate the toner loading amount from the halftone dot ratio, and the pixel value can be used as it is. good.

FIG. 11 is a diagram illustrating the relationship between the toner loading amount, the fixing temperature control, and the cleaning control according to the first embodiment.

In S601 of FIG. 6, the CPU 210 receives the analysis result of the image data from the image analysis unit 307, and controls the fixing temperature control unit 208 based on the analysis result and the environmental information from the environment sensor 213. The fixing temperature is controlled as shown in 11.

Further, in S603 of FIG. 6, the CPU 210 receives the analysis result of the image data from the image analysis unit 307, controls the cleaning control unit 209 based on the analysis result and the environment information from the environment sensor 213, and is shown in FIG. So that you control how often you issue cleaning requests.

For example, in a high temperature / high humidity environment, when a page has a low loading portion having a predetermined area, a shortage of heat quantity is likely to occur. Therefore, the fixing temperature of the page (paper unit) is raised by 3 degrees from the usual level. The temperature rise according to the presence or absence of the low loading amount portion shall be performed within a range in which the offset due to the excessive heat amount does not occur in the high loading amount portion.

In other environments, the temperature does not rise due to excessive heat. And the frequency of cleaning requests is increased by 10%. In other environments, the temperature is not lowered according to the low loading portion so that the heat quantity is not insufficient when the high loading portion is present. This is because the decrease in fixability in the high loading portion has a greater effect than in the low loading portion.

FIG. 12 is a flowchart illustrating the fixing temperature control of S601 of FIG. 6 by the image forming apparatus according to the first embodiment.

First, in S1201, the CPU 210 acquires the environmental information detected by the environmental sensor 213, here, the temperature and humidity in the environment in which the image forming apparatus 101 is installed. Next, the process proceeds to S1202, and the CPU 210 acquires from the RAM 211 information indicating whether or not the current page to be printed, which is stored in the above-mentioned S713, includes a low loading portion of a predetermined area or more. Next, the S1203 advance CPU 210 determines whether the environment in which the image forming apparatus 101 is installed is high temperature and high humidity. If this is not the case, the temperature of the fuser according to the first embodiment is not controlled, so the process proceeds to S1206, normal fixing temperature control is performed, and this process is completed.

On the other hand, if it is determined in S1203 that the environment in which the CPU 210 is installed is high temperature and high humidity, the process proceeds to S1204, and the CPU 210 determines whether or not it includes a low loading portion of a predetermined area or more, that is, a low toner region. If it is determined that the low toner region is not included, the process proceeds to S1206, but if not, the process proceeds to S1205, for example, as shown in FIG. 11, the temperature of the fuser is controlled to rise by 3 ° C., and this process ends. ..

Since it is necessary to improve the fixability of the image on a page-by-page basis in the temperature control of the fuser, the control is performed in real time.

FIG. 13 is a flowchart illustrating the cleaning control of S603 of FIG. 6 by the image forming apparatus according to the first embodiment.

First, in S1301, the CPU 210 acquires the environmental information detected by the environmental sensor 213, here, the temperature and humidity in the environment in which the image forming apparatus 101 is installed. Next, the process proceeds to S1302, and the CPU 210 acquires from the RAM 211 information indicating whether or not the current page to be printed, which is stored in the above-mentioned S713, includes a low loading portion of a predetermined area or more. Next, the CPU 210 advances to S1303 and determines whether the environment in which the image forming apparatus 101 is installed is high temperature and high humidity. If this is the case, since the cleaning control of the fuser according to the first embodiment is not performed, the process proceeds to S1306, normal cleaning control is performed, and this process is completed.

On the other hand, if it is determined in S1303 that the environment in which the CPU 210 is installed is not high temperature and high humidity, the process proceeds to S1304, and the CPU 210 determines whether or not it includes a low loading portion of a predetermined area or more, that is, a low toner region. If it is determined that the low toner region is not included, the process proceeds to S1306, but if not, the process proceeds to S1305, for example, as shown in FIG. 11, the frequency of cleaning requests is controlled to increase by 10%, and this process ends. ..

The control of the frequency of this cleaning request does not have to be in real time, and the easiness of contamination by the offset toner is counted as an offset level value, for example, +1 in normal times, and +1.1 if the frequency is increased by 10%. .. Then, when the offset level value exceeds a predetermined threshold value (for example, 100), a cleaning request is issued to the print unit 206 or the UI unit 205 immediately after one page or immediately after the print job.

As described above, according to the first embodiment, the deterioration of the formed image can be suppressed by controlling the temperature of the fuser with respect to the page having the low loading amount portion where the deterioration of the image quality is conspicuous. In addition, good image quality can be maintained by increasing the frequency of cleaning requests for pages having a low loading amount portion where stains due to offset toner tend to accumulate in the fuser.

Further, according to the first embodiment, it is possible to prevent the deterioration of the image by controlling the fixing temperature according to the presence / absence of the low loading amount portion where the deterioration of the image quality is conspicuous and the environmental information.

In addition, it is possible to prevent image deterioration by controlling the frequency of cleaning requests for the fuser according to the presence or absence of a low loading portion where dirt due to offset toner tends to accumulate in the fuser and environmental information.

[Embodiment 2]
Next, as the second embodiment of the present invention, the relationship between the portion where the amount of toner is applied (highly loaded portion) and the frequency of temperature control and cleaning request of the fuser will be described. Since the configuration of the image forming apparatus 101 and the system configuration including the image forming apparatus 101 according to the second embodiment are the same as those of the first embodiment, the description thereof will be omitted.

FIG. 14 is a diagram illustrating the relationship between the amount of toner loaded, the temperature control of the fuser, and the frequency of cleaning requests according to the second embodiment.

In FIG. 14, the image analysis unit 307 determines in S702 of FIG. 7 whether or not there is a high loading amount portion in which the threshold value of the toner loading amount is 200% or more. It should be noted that the high loading amount portion has a large influence on image formation, such as causing the paper to wrap around the fixing film strongly when the fixability is lowered, and therefore has a smaller area (for example, the low loading amount portion) than the low loading amount portion. It is supposed to be detected at 0.2 mm × 0.2 mm).

Further, the high loading amount portion and the low loading amount portion include the case where the maximum loading amount of the high loading amount portion is switched between 200% and 230% according to the setting of the high saturation printing mode in the item list 502 of FIG. It shows the frequency of fixing temperature control and cleaning request when mixed. For example, in the high-saturation printing mode 230% in a high-temperature / high-humidity environment shown in 1401, the amount of heat required to melt the toner is required to increase the amount of toner in the high-loading portion more than usual. Therefore, the temperature of the fuser is raised by 5 ° C. than usual.

In addition, on pages where a high loading amount portion and a low loading amount portion are mixed, priority is given to the condition where the temperature is higher. For this reason, in a high-saturation printing mode (230%) and a low loading amount (50% (large area)) in a high-temperature and high-humidity environment shown by 1402, the required temperature is higher than usual in the low loading amount portion. Is also raised by 55 ° C. Therefore, the low loading amount portion is not insufficient in heat quantity but excessive in heat quantity, so that the frequency of cleaning request is increased by 5%.

FIG. 16 is a flowchart illustrating the fixing temperature control of S601 of FIG. 6 by the image forming apparatus 101 according to the second embodiment.

First, in S1601, the CPU 210 acquires the environmental information detected by the environmental sensor 213, here, the temperature and humidity in the environment in which the image forming apparatus 101 is installed. Next, the process proceeds to S1602, and the CPU 210 acquires from the RAM 211 information indicating whether or not the current page to be printed, which is stored in the above-mentioned S713, includes a low-loading portion having a predetermined area or more and a high-saturation printing mode. Next, the S1603 advance CPU 210 determines whether the environment in which the image forming apparatus 101 is installed is high temperature and high humidity, and if so, proceeds to S1604, and if not, proceeds to S1611. In S1604, the CPU 210 checks whether or not the high-saturation printing mode is set, and if it is in the high-saturation printing mode, proceeds to S1605, raises the temperature of the fuser by 5 ° C., and ends this process. When the high-saturation printing mode is not set in S1604, the process proceeds to S1606, and the CPU 210 determines whether or not the low-loading portion and the high-loading portion are mixed. If it is determined that the mixture is mixed, the process proceeds to S1607, it is determined whether or not the mixture includes the high-saturation printing mode, if the high-saturation printing mode is included, the process proceeds to S1605, and if not, the process proceeds to S1608. The temperature is raised by 3 ° C. to end this process. Further, if it is determined in S1606 that they are not mixed, the process proceeds to S1609, and the CPU 210 determines whether or not this page includes a low loading portion. When the low loading portion is included, the process proceeds to S1608 to raise the temperature of the fuser by 3 ° C., and when not, the process proceeds to S1610 to set the temperature of the normal fuser to end this process.

Further, if it is determined in S1603 that the installed environment is not high temperature and high humidity, the process proceeds to S1611 and the CPU 210 determines whether or not the high saturation printing mode is set. If it is determined in S1611 that the high-saturation printing mode is set, the process proceeds to S1608 to raise the temperature of the fuser by 3 ° C., but if not, the process proceeds to S1612. In S1612, the CPU 210 determines whether or not the low loading portion and the high loading portion are mixed. Here, if it is determined that they are not mixed, the process proceeds to S1610 to set the temperature of the normal fuser, but if they are mixed, the process proceeds to S1613 to determine whether or not the high saturation printing mode is set. If it is determined that the high-saturation printing mode is set, the process proceeds to S1608 to raise the temperature of the fuser by 3 ° C., and if not, the process proceeds to S1610 to set the temperature of the normal fuser to perform this process. finish.

FIG. 17 is a flowchart illustrating cleaning control of S603 of FIG. 6 by the image forming apparatus according to the second embodiment.

First, in S1701, the CPU 210 acquires the environmental information detected by the environmental sensor 213, here, the temperature and humidity in the environment in which the image forming apparatus 101 is installed. Next, the process proceeds to S1702, and the CPU 210 acquires from the RAM 211 information indicating whether or not the current page to be printed, which is stored in the above-mentioned S713, includes a low-loading portion having a predetermined area or more and a high-saturation printing mode. Next, the S1703 advance CPU 210 determines whether the environment in which the image forming apparatus 101 is installed is high temperature and high humidity, and if so, proceeds to S1704, and if not, proceeds to S1708. In S1704, the CPU 210 determines whether or not the current page has a low loading portion and a high loading portion mixed. If it is determined that they are not mixed here, the process proceeds to S1705, the cleaning frequency is set to a normal frequency, and this process ends.

On the other hand, if it is determined in S1704 that the low load portion and the high load portion are mixed, the process proceeds to S1706, and the CPU 210 checks whether the high saturation print mode is set, and if the high saturation print mode is set, the S1707 is displayed. move on. In S1707, the CPU 210 increases the cleaning frequency by 5% and ends this process. On the other hand, when the high-saturation printing mode is not set in S1704, the process proceeds to S1705, a normal cleaning frequency is set, and this process ends.

Further, if it is determined in S1703 that the installed environment is not high temperature and high humidity, the process proceeds to S1708, and the CPU 210 determines whether or not the low loading portion and the high loading portion are mixed. If it is determined that they are mixed here, the process proceeds to S1711, and the CPU 210 determines whether or not the high-saturation printing mode is set. If it is determined in S1711 that the high-saturation printing mode is set, the process proceeds to S1712 to increase the cleaning frequency by 15%, but if not, the process proceeds to S1710 to increase the cleaning frequency by 10% and end this process. do.

Further, if it is determined in S1708 that the low loading portion and the high loading portion are not mixed, the process proceeds to S1709. In S1709, the CPU 210 determines whether or not there is a low loading portion of a predetermined area or more, and if it determines that there is, the process proceeds to S1710, the cleaning frequency is increased by 10%, and this process is completed. On the other hand, if it is determined that there is no low loading portion, the process proceeds to S1705, the cleaning frequency is set to a normal frequency, and this process ends.

The temperature value to be raised, the frequency of cleaning, and the like described in the second embodiment are not limited to the above-mentioned numerical values.

As described above, according to the second embodiment, even when the low loading amount portion and the high loading amount portion are mixed in the image on one page, the temperature control and the cleaning control of the fuser are appropriately executed to form the image. It has the effect of preventing deterioration of the resulting image.

[Embodiment 3]
Next, as the third embodiment of the present invention, the same main scanning position of the fuser (fixing roller / fixing film) and the region where the loading amount is low a plurality of times in succession at the sub-scanning position are detected, and the area thereof is detected. An example of detecting whether or not is equal to or more than a predetermined value will be described. Since the configuration of the image forming apparatus 101 and the system configuration including the image forming apparatus 101 according to the third embodiment are the same as those of the first embodiment, the description thereof will be omitted.

If a low-load toner image is fixed multiple times in succession at the same position on the fuser (fixing roller / fixing film), the amount of heat fluctuates intensively at that position, resulting in a decrease in fixability. It occurs more prominently. For example, when A4 (210x297mm) paper and the peripheral length of the fixing roller are 60 mm, the same position of the fixing roller is fixed five times (from 297/60 = 4.45) while printing one page on the paper. It will be.

Therefore, in the third embodiment, the position of the local region on the sheet, which is a low loading amount generated during printing of one page, is mapped to the coordinate system (fixer coordinates) of the rollers of the fuser, and each main of the fuser coordinates is mapped. The number of times a low loading amount is continuously generated is counted at the scanning position and its sub-scanning position. The area where the low loading area is continuous is measured at the low loading overlapping position where the maximum value of this number exceeds a predetermined number (2 in this case). The area measurement method will be described basically using the same method as in the first embodiment, but the present invention is not limited to this.

First, in the area measurement, the maximum value at which the low loading amount is continuous in the sub-scanning direction is obtained at each main scanning position of the fuser coordinates, and the maximum value is a predetermined value (10 mm in this case). Detect the excess part. Then, the maximum amount in which the portion having the continuous amount in the sub-scanning direction equal to or larger than the predetermined value is continuous in the main scanning direction is obtained, and it is determined whether or not it exceeds the predetermined value (here, 10 mm). In this way, when a page having an area where the portion having a low loading amount exceeds 10 × 10 mm is detected a plurality of times in succession in the fuser coordinates, the temperature control (S601) of the fuser at the time of fixing the page is performed.

FIG. 18 is a flowchart illustrating an image analysis process by the image analysis unit 307 of the image forming apparatus 101 according to the third embodiment. Here, as an example, a portion where the toner loading amount in the local region is 10 to about 70% is defined as a low loading amount portion, and a portion (10 mm x 10 mm) in which the low loading amount is repeated twice or more at the same position of the fuser coordinates is detected. .. Here, it is assumed that the CPU 210 expands the program stored in the storage unit 204 into the RAM 212 and executes the expanded program to execute the process shown in this flowchart. In FIG. 18, the same processing as in FIG. 7 described above is designated by the same reference numerals.

First, in S701, the CPU 210 analyzes the CMYK data after the image forming process received in S405 of FIG. 4 to calculate the toner loading amount (TnrSum) in the local region unit. Next, the process proceeds to S702, and the CPU 210 determines whether or not the loading amount (TnrSum) of the local region calculated in S701 falls within the threshold range specified in advance. Here, if it is determined that the value is within the threshold range, PickupTnrArea = 1, and if it is not within the threshold range, PickupTnrArea = 0. Here, as an example of the threshold range, 10% <TnrSum <70% is set, but the present invention is not limited to this.

Next, the process proceeds to S1801, and the CPU 210 calculates the fuser coordinates (fpx, fpy) corresponding to each local region in the page. Since the size at which the image quality is conspicuously deteriorated in the low loading amount portion is a large size exceeding the mm size, the fuser coordinates may be obtained for the loading amount of the coarsely sampled local region such as 100 dpi unit. For example, when both the local area coordinates (kpx, kpy) and the fuser coordinates (fpx, fpy) are set to 100 dpi.
fpx = kpx
fpy = kpy% (perimeter of the fuser roller)
Will be. In this equation,% means the remainder. The fuser coordinates refer to the coordinates on the fixing roller / fixing film, and here, the peripheral length of the fixing roller is 60 mm (about 236 pix in terms of 100 dpi) as an example.

Next, the process proceeds to S1802, and the CPU 210 determines whether or not the position indicated by the fuser coordinates (fpx, fpy) obtained in S1801 has a low loading amount (PickupTnrArea = 1) in the local area of the page corresponding to the fuser coordinates. Judgment is made based on whether or not PickupTnrArea is "1". Here, if the position indicated by the fuser coordinates is a low loading amount, the process proceeds to S1803, and the CPU 210 advances to S1806 by incrementing the duplication counter FuserPosRepeat [fpx] [fpy] by +1. On the other hand, when the PickupTnrArea of the local area of the page corresponding to the fuser coordinates is "0", it is judged that the continuation of the low loading amount is interrupted, and the process proceeds to S1804, and the value of the duplicate counter at that time is the duplicate maximum value FuserPosRepeatMax. Record in [fpx] [fpy]. Specifically, the duplicate maximum value FuserPosRepeatMax [fpx] [fpy] is compared with the duplicate counter FuserPosRepeat [fpx] [fpy], and the duplicate maximum value FuserPosRepeatMax [fpx] [fpy] is updated with the larger value. Then, since the continuation of the low loading amount is interrupted, the duplication counter is cleared in S1805 and the process proceeds to S1806. In S1806, the CPU 210 determines whether or not the processing for the page is completed, and if not, returns to S1802. In this way, the value of the maximum overlap value FuserPosRepeatMax [fpx] [fpy] at each fuser coordinate is obtained for each page to be printed.

Next, the process proceeds to S1807, and the CPU 210 determines whether or not the maximum overlap value in each fuser coordinate exceeds a predetermined threshold value (repeatThre (here, 2). If the threshold value is exceeded, the threshold value is set to S1808. Proceed and proceed to S1810 with duplicate determination FuserPosRepeatThreOver [fpx] [fpy] = 1. On the other hand, if it is below the threshold value, proceed to S1809 and proceed to S1810 with duplicate determination FuserPosRepeatThreOver [fpx] [fpy] = 0. Although (repeatThre) is set to "2", the present invention is not limited to this. Further, the value may be changed according to the conditions such as the engine speed and the environmental condition where the fixing performance changes. The result of the duplication determination in the coordinates will be obtained.

In S1810, the CPU 210 determines whether or not the overlap determination FuserPosRepeatThreOver [fpx] [] = 1 at each main scanning position of the fuser coordinates, and if so, proceeds to S1811 and proceeds to S1811, and the continuous amount yRun [which is continuous in the sub-scanning direction. fpx] is incremented by 1 to proceed to S1814. Here, unlike the first embodiment, the amount of overlapping portions of the fuser coordinates in each main scanning direction is obtained in the sub-scanning direction, not the result of determining the amount of the local area on the page. Since the rollers and film of the fuser are rotating, the same coordinates are referred to periodically and repeatedly in the sub-scanning direction. Therefore, when the continuity is not interrupted at the lower end fpy = 235 (perimeter around the fuser-1 pix), it is necessary to consider the possibility that the continuity wraps around to the upper end fpy = 0. Therefore, when FuserPosRepeatThreOver [fpx] [] = 1, it is determined that the low loading portion is continuous in the sub-scanning direction, and the continuous amount yRun [fpx] is incremented by 1.

However, in the case of FuserPosRepeatThreOver [fpx] [0] = 1 in which a low loading amount portion is generated from the upper end, the continuous amount is stored in yRunUpperObj [fpx] when the continuity is interrupted for the first time. And, when FuserPosRepeatThreOver [fpx] [235] = 1 where the lower end has a low loading amount, it is connected with the continuous amount at the upper end and updated with the continuous amount yRun [fpx] = yRun [fpx] + 1 + yRunUpperObj [fpx]. do.

On the other hand, if FuserPosRepeatThreOver [fpx] [] = 0 in the duplication determination of S1810, it is determined that the continuity in the sub-scanning direction is interrupted, and the process proceeds to S1812. In S1812, the CPU 210 records the maximum continuous amount yRunMax [fpx] of the sub-scan continuity. Specifically, the maximum continuous amount yRunMax [fpx] is compared with the continuous amount yRun [fpx] at that time, and the maximum continuous amount yRunMax [fpx] is updated with the larger value. Then, in S1813, the continuous amount yRun [fpx] = 0 is set, and the process proceeds to S1814. In this way, in S1814, it is determined whether or not the processing has been performed for one page, and if the processing has not been performed for one page, the process returns to S1810, and when the processing for one page is completed, the process proceeds to S704 (FIG. 7).

Then, in the same manner as in the first embodiment, the processes S704 to S709 of FIG. 7 are executed, and the area of the portion where the loading amount is low is calculated a plurality of times in succession in the sub-scanning direction at each main scanning position of the fuser coordinates. .. Based on the result detected in the above processing, the CPU 210 in S709 stores in the RAM 212 that the page includes a low loading portion having an area equal to or larger than a predetermined value, and ends this processing. Then, when the area exceeds, for example, 10x10 mm, the fixing temperature control and the cleaning control are performed as pages in which the fixing property is remarkably lowered.

FIG. 19 is a diagram illustrating an outline of a process for obtaining a low loading area according to the flowchart of FIG. 18 in the third embodiment.

In FIG. 19, 1901 indicates a low loading area within the page, and 1902 maps it as a low loading portion of the fuser coordinates. Reference numeral 1903 indicates a process of detecting a portion in which a low loading portion is continuous by a predetermined amount in the sub-scanning direction at each main scanning position of the fuser coordinates. 1904 shows an example in which a portion where the low loading portion is continuous by 10 mm or more in the sub-scanning direction is detected at each main scanning position in the fuser coordinates. Further, 1905 detects a region in which the low loading portion is continuous by 10 mm or more in the sub-scanning direction and is continuous by 10 mm or more in the main scanning direction.

In FIG. 18, the overlap amount of the fuser coordinates corresponding to the print data of one page is counted, and then the overlap determination is performed to obtain the area where the low loading amount portion is continuous in the main scan and the sub scan directions. , The present invention is not limited to this.

FIG. 20 is a flowchart illustrating a modification of the image analysis process of FIG. 18 by the image analysis unit 307 of the image forming apparatus 101 according to the third embodiment. Here, the steps common to FIG. 18 are indicated by the same reference numbers, and their description will be omitted.

If it is determined in S2001 that it is the end in the sub-scanning direction, the process proceeds to S2002, and the CPU 210 determines whether the load amount calculation and the overlap count of the fuser coordinates have been performed up to a position that is a constant multiple of the rotation cycle of the fuser. It is determined whether the double exceeds the threshold value (repeatThre = 2). Here, if the determination result is Yes, the process proceeds to S2003, the processes S1807 to S1814 described with reference to FIG. 18 and the processes S704 to S709 of FIG. The area where the quantity part is continuous is calculated. Then, in S2005, the CPU 210 determines whether or not a low loading portion having an area of 10 x 10 mm already exists in the N circumferences of the fuser (N is repeatThre or more and 2 or more). Then, if it is determined that the fixability of the page is low because there is a low loading amount portion having an area of 10x10 mm, this process is terminated, but if not, the process proceeds to S2006 and the calculation position of the toner loading amount is moved. Then, the process proceeds to S701, and the above-mentioned process is executed.

Thereby, for example, if the page has a low loading amount portion of 10 x 10 mm on the page tip side, it can be determined that the page has low fixing property at a higher speed.

As described above, according to the third embodiment, at the same position of the fuser (fixing roller / fixing film), a portion having a low loading amount is repeatedly fixed, and a page in which heat quantity fluctuations are concentrated is detected. can do. Thereby, the fixing temperature control and the cleaning control can be performed on such a page.

[Embodiment 4]
In the third embodiment described above, the area of the low loading portion in the fuser coordinates was detected. However, it is a high-cost mechanism such that it is necessary to have an overlap counter for the peripheral length of the fuser member (fixing roller / fixing film).

Further, when the area of the low loading portion is set in consideration of the peripheral length of the fixing device (fixing roller / fixing film) by the method of the first embodiment described above, a very large area is specified. Moreover, detection omission also occurs. For example, when the peripheral length of the fuser (fixing roller / fixing film) is 60 mm, in order to detect a page in which 10x10 mm is repeated at the same position for two cycles, the method of the above-described first embodiment detects an area of 10x70 mm. There is a need to. Further, it is good if the low loading amount portion is continuous by 10x70 mm, but for example, as shown in FIG. 21, the low loading amount region of 10x10 mm is divided into a plurality of parts, and the low loading amount is at the same position for two cycles. Cannot be detected if the area of

Therefore, in the fourth embodiment, if the gap portion from the start object of the low loading portion to the next low loading portion is a predetermined size or less, these two low loading portions are used as a continuous low loading region. Find the area. As a result, even if the low loading portion is divided into a plurality of areas in the sub-scanning direction, it is possible to determine whether or not the same position of the fuser coordinates is a page for continuously fixing the low loading portion. Since the configuration of the image forming apparatus 101 and the system configuration including the image forming apparatus 101 according to the fourth embodiment are the same as those of the first embodiment, the description thereof will be omitted.

FIG. 22 is a flowchart illustrating an image analysis process by the image analysis unit 307 of the image forming apparatus 101 according to the fourth embodiment. Here, it is assumed that the CPU 210 expands the program stored in the storage unit 204 into the RAM 212 and executes the expanded program to execute the process shown in this flowchart.

Here, as an example, it is assumed that the portion where the local loading amount is 10 to about 70% is the low loading amount portion, the peripheral length of the roller of the fuser is 60 mm, and the low loading amount 10x70 mm area (gap 50 mm is allowed) is detected. As a result, as shown in FIG. 21, a portion having a low loading amount of 10 × 10 mm, which is divided into a plurality of parts for two consecutive cycles, is detected.

First, in S701, the CPU 210 analyzes the CMYK data after the image formation process received by the image analysis unit 307 and calculates the loading amount (TnrSum) in units of local regions. Next, the process proceeds to S702, and the CPU 210 determines whether the calculated loading amount of the local region falls within the threshold range specified in advance. If it falls within the range, PickupTnrArea = 1, and if it does not fall within the range, PickupTnrArea = 0. Here, 10% <TnrSum <70% is set as an example of setting the threshold range, but the present invention is not limited to this.

Next, proceeding to S2201, the CPU 210 obtains a continuous amount yRun [main scanning position] in which the local region where PickupTnrArea = 1 is continuous in the sub-scanning direction at each main scanning position. In the fourth embodiment, unlike the first embodiment, when a specific condition is met, a portion having a non-low loading amount is treated as a gap, and the low loading region including the gap is assumed to be continuous in the sub-scanning direction. Count. The details will be described later with reference to the flowchart of FIG.

Then, in the same manner as in the first embodiment, S704 to S709 are carried out to calculate the area of the portion having a low loading amount that is repeatedly fixed by the fixing device. Then, when the area exceeds, for example, 10x70 mm, it is determined that the page has a decrease in fixability, and the fixing temperature control and the cleaning control are performed in the image formation of the page.

FIG. 23 is a flowchart illustrating the process of S2201 of FIG. 22.

In S2301, the CPU 210 determines whether or not the sub-scanning position to be processed has reached the end of the page in the sub-scanning direction. This process of reaching the end in the sub-scanning direction ends, but if not, the process proceeds to S2302. In S2302, the CPU 210 determines whether or not PickupTnrAre, which is the result of determining the local loading amount, is "1", that is, whether or not the local region is the low loading amount portion. Here, when the local region is a low loading portion, it is determined that the low loading portion is continuous in the sub-scanning direction, and the process proceeds to S2303. On the other hand, if it is not a low loading portion, the process proceeds to S2304, and it is determined whether a gap is generated in the sub-scanning direction or the continuity is interrupted.

When the loading amount portion is continuous in the sub-scanning direction, the CPU 210 increments the continuous amount yRun [main scanning position] of the low loading amount portion in the sub-scanning direction by +1 in S2303. In addition, the continuous amount of gaps in the sub-scanning direction accumulated up to that point is added to the low-loading amount of sub-scanning continuous amount yRun [main scanning position] and treated as a continuous low-loading portion including the gaps. .. That is, here, yRun [main scanning position] + sukima_yRun [main scanning position] = yRun [main scanning position]. Then, the gap continuous amount sukima_yRun [main scanning position] = 0 is cleared, and the process proceeds to S2308.

On the other hand, in S2304, the CPU 210 sets the portion where the low loading portion up to the current sub-scanning position is continuous as the start object, and the continuous amount in the sub-scanning direction at that time is the threshold value FirstObjectSizeThre (= 10 mm) specified in advance. ) Is exceeded. Here, if the continuous amount of the start object exceeds the threshold value, the process proceeds to S2305, but if not, it is determined that the continuity in the sub-scanning direction is lost and the process proceeds to S2306.

In S2305, the CPU 210 determines whether or not the continuous amount of the gap portion, which is not a low loading amount, is shorter than the predetermined threshold value sukima_yRunThre (50 mm in the example of FIG. 21). If the gap continuous amount is shorter than the threshold value, the process proceeds to S2307, the gap continuous amount is incremented by 1, and the process proceeds to S2308. On the other hand, when the gap continuous amount is longer than the threshold value, it is determined that the continuity of the low loading amount portion is interrupted, and the process proceeds to S2306. In S2306, the CPU 210 stores the maximum value yRunMax [main scan position] of the sub-scan continuity of the low loading portion. Specifically, the maximum continuous amount yRunMax [main scanning position] is compared with the current continuous amount yRun [main scanning position], and the value of the maximum continuous amount yRunMax [main scanning position] is updated with the larger value. .. Then, the continuous amount yRun [main scanning position] = 0 is set, and the gap continuous amount sukima_yRun [main scanning position] = 0 is cleared, and the process proceeds to S2308.

Next, in S2308, the CPU 210 moves to the next sub-scanning position and refers to the local loading amount determination result PickupTnrArea. Then, in S2301, the processing of S2301 to S2308 is repeated until the processing for the end portion in the sub-scanning direction is completed.

FIG. 21 is a diagram illustrating an example of determining the continuity of the low loading portion in the sub-scanning direction in the fourth embodiment.

Here, a gap of 50 mm 2102 is generated between the starting object 2100 of the low loading portion of 10 mm × 10 mm and the next second object 2101 of 10 mm × 10 mm. Here, it is determined whether the length of the gap 2102 exceeds the threshold value sukima_yRunThre (50 mm). If the length of the gap 2102 is equal to or less than the threshold value sukima_yRunThre (50 mm), the start object 2100 and the second object 2101 are treated as continuous. Therefore, in the example of FIG. 21, when the peripheral length of the roller of the fuser is 60 mm and the gap 2102 between the start object 2100 and the second object 2101 is 50 mm, this region has an area of 10 mm × 70 mm. It will be processed as 2103.

As described above, by executing the process shown in the flowchart of FIG. 23, for example, as shown in FIG. 21, two low load portions separated in the sub-scanning direction are treated as continuous low load portions. Can be done. That is, in the case of FIG. 21, it can be treated as an object in which the low loading portion is continuous by 70 mm in the sub-scanning direction.

As described above, according to the fourth embodiment, even if an overlap counter corresponding to the peripheral length of the fuser member (fixing roller / fixing film) is not provided, the amount of repetitive low loading is repeated at the same position of the fuser member. You can detect the page where the part occurs. Thereby, when the image of such a page is formed, the temperature control of the fuser and the cleaning control of the photoconductor can be performed.

In the fourth embodiment, the case where there is a gap in the low loading region in the sub-scanning direction has been described, but the same may be applied to the main scanning direction. As a result, even if there is a gap in the main scanning direction, for example, as shown by the dotted line of a thin line, if the length of the gap is less than the threshold value, it is ignored and the low loading portion continues in the main scanning direction. It can be detected as an area.
(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

The present invention is not limited to the above embodiments, and various modifications and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to make the scope of the present invention public, the following claims are attached.

101 ... image forming device, 203 ... control unit, 204 ... storage unit, 205 ... UI unit, 206 ... printing unit, 207 ... image processing unit, 208 ... fixing temperature control unit, 209 ... cleaning control unit

Claims (14)

An image forming apparatus that forms an image in an electrophotographic process.
A receiver that receives image data and
An image forming means for forming a toner image on a recording paper based on the image data received by the receiving unit, and an image forming means.
A fuser that heat-fixes the toner image formed by the image forming means to the recording paper, and
It has a temperature control means for setting a fixing temperature at the time of heat fixing by the fixing device and controlling the temperature of the fixing device so as to reach the set fixing temperature.
The temperature control means
By analyzing the image data received by the receiving unit, the first loading amount region in which the toner loading amount per unit area transferred to the recording paper is within the range from the first threshold value to the second threshold value. Then, a process is performed to detect a second loading amount region in which the toner loading amount per unit area transferred to the recording paper exceeds the third threshold value.
When said mixed first applied amount region and the second bearing amount region is detected, the mixing of the first toner amount region and the second bearing amount region is not detected and the first The fixing temperature of the fuser is set to a higher temperature than when the loading area is not detected, the third threshold value is larger than the second threshold value, and the detected area of the first loading area is , An image forming apparatus characterized in that it is larger than the detection area of the second loading area. The image forming apparatus according to claim 1, further comprising a cleaning control means for controlling cleaning of the fuser when image forming is performed based on image data including the first loading area. The temperature control means has an amount in which a region in which the amount of the toner loaded is smaller than the second threshold value is continuous in the sub-scanning direction at a position in the main scanning direction of the image data, and is continuous in the sub-scanning direction. When the area is continuous in the sub-scanning direction and the main scanning direction based on the amount of the area continuous in the main scanning direction, and the area is equal to or larger than a predetermined size. The image forming apparatus according to claim 2, wherein the first loading area is detected. The temperature control means obtains an area in which the first loading area is continuous by giving priority to a continuous amount in which the area is continuous in the sub-scanning direction in consideration of cleaning by the cleaning control means. The image forming apparatus according to claim 3. The temperature control means has a calculation means for calculating the halftone dot ratio from the number of pixels included in the local region of the image data, and obtains the loading amount of the transfer agent in the first loading amount region from the halftone dot ratio. The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is used. The image forming apparatus according to any one of claims 2 to 4, further comprising an environmental sensor for detecting an environmental state in which the image forming apparatus is installed. The image forming apparatus according to claim 2, wherein the cleaning control means controls the frequency of requesting cleaning of the fuser. The sixth aspect of the present invention is that when the environmental state detected by the environmental sensor indicates a temperature / humidity environment higher than a predetermined value, the temperature control means raises the temperature of the fuser by a predetermined amount. The image forming apparatus according to the description. The eighth aspect of the present invention, wherein the cleaning control means increases the frequency of requesting cleaning of the fuser by a predetermined amount when the environmental state detected by the environmental sensor does not indicate a high humidity environment. Image forming device. The temperature control means determines whether or not a region in which the pre-described amount is smaller than the second threshold value and a region in which the pre-described amount is larger than the second threshold value coexist.
The eighth aspect of the present invention is characterized in that the temperature control means raises the temperature of the fuser by a predetermined amount when it is determined that they are mixed and the environmental state detected by the environmental sensor indicates a high humidity environment. The image forming apparatus according to the description. The temperature control means determines whether or not a region in which the toner loading amount is smaller than the second threshold value and a region in which the previously described amount is larger than the second threshold value coexist.
When it is determined that they are mixed and the environmental state detected by the environmental sensor does not indicate a high humidity environment, the cleaning control means increases the frequency of requesting cleaning of the fuser by a predetermined amount. The image forming apparatus according to claim 9. The temperature control means calculates the amount of toner loaded in the local area, and when the calculated amount of toner loaded is equal to or greater than the first threshold value and less than the second threshold value, the fuser coordinates mapped to the fuser. The number of times the first loading area is continuous is counted at each position of the above, and the fixing is based on the continuous area of the area determined by the fuser coordinates that the first loading area is continuous a plurality of times. The image forming apparatus according to any one of claims 1 to 11, wherein the temperature is set. The temperature control means is characterized in that even if there is a gap between the first loading areas, if the gap is equal to or less than a predetermined threshold value, the area is calculated as a continuous area. 12. The image forming apparatus according to 12. The image forming apparatus according to claim 13, wherein the predetermined gap is a value determined based on the peripheral length of the fixing roller of the fixing device.

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