JP2021056445A - Image forming apparatus - Google Patents

Abstract

To adjust a fixing temperature of a fixing unit without reducing productivity of printing to prevent fixing failure caused by an insufficient fixing temperature, and reduce power consumption.SOLUTION: An image forming apparatus has: a page area placement amount detection unit that detects a placement amount of toner in a page area for image data; a division area placement amount detection unit that detects, for each of division areas, a placement amount of toner in the division area for the image data; a fixing unit that can adjust to an individual temperature for each of the division areas, and fixes a toner image to a recording medium; and a control unit that sets the temperature for each of the division areas of the fixing unit based on results of detection performed by the page area placement amount detection unit and the division area placement amount detection unit. The control unit takes a page to which a toner image is to be fixed as one page ahead, and sets the temperature for each of the division areas of the fixing unit, based on a placement amount of toner in a page area of every image data for P1 pages ahead and a placement amount of toner for each of the division areas of every image data for P2 pages ahead smaller than the number of pages for P1 pages ahead.SELECTED DRAWING: Figure 7

Description

The present invention relates to an image forming apparatus that heat-fixes a toner image formed by an electrophotographic method on a recording medium.

In an image forming apparatus that heat-fixes a toner image formed by an electrophotographic method on a recording paper, a technique for determining a fixing temperature at a fixing portion according to the amount of coloring material (hereinafter referred to as the toner loading amount) placed on the recording paper. It has been known. As a result, it is possible to suppress fixing due to overtemperature while preventing fixing failure due to insufficient fixing temperature, and the power consumption of the fixing portion is reduced.

In Patent Document 1, considering that the fixing temperature of the fixing portion cannot be changed abruptly, the high toner loading amount of the image data of a plurality of pages (for example, 5 pages) ahead is detected, and the fixing temperature is stepwise from 5 pages before. The technology to be raised to is disclosed. By controlling in this way, it is possible to avoid fixing defects while maintaining printing productivity.

Patent Document 2 discloses a technique in which a plurality of heating elements for fixing are provided in a width direction orthogonal to the transport direction of the recording paper, and the fixing temperature is determined according to the image formation pattern of the recording paper for each heating element. Has been done. By controlling in this way, it is possible to reduce power consumption while avoiding fixing defects.

On the other hand, a general image forming apparatus has a page aggregation function and has a means for saving the number of sheets to be output. Page aggregation is the printing of a plurality of pages of images on a single sheet of paper. For example, two A4 size images can be arranged side by side and printed on A3 size paper, or an A4 size image can be reduced to 1/2 size and two pages of images can be printed on one sheet of A4 size paper. Is. The process of performing scaling processing and rotation processing on the input image to the image forming apparatus in this way to generate an image pattern of the recording paper is called layout processing.

Japanese Unexamined Patent Publication No. 2015-1546 Japanese Unexamined Patent Publication No. 2015-52722

Here, in order to appropriately control the fixing temperature for each of a plurality of heating elements in the fixing portion while performing the layout processing, the image data after the layout processing is used to set the heat generation region by each heating element. In addition, it is necessary to calculate the amount of toner loaded.

On the other hand, in the layout process, the processing content is determined according to the orientation of the recording paper stored in the cassette, in addition to the instruction setting from the user. Therefore, the process of calculating the toner loading amount according to the heat generating region by each heating element using the image data after the layout processing is performed on the scan input side (image reading) in, for example, the image processing flow of the copying machine. It is generally executed on the print output side (image printing side) after this process, not on the side).

However, in order to gradually raise the fixing temperature over multiple pages, it takes more time as the number of pages increases to calculate the amount of toner loaded according to the heat generation area of each heating element up to the image data of multiple pages ahead. It will take. Therefore, although it is possible to reduce the power consumption while avoiding the fixing failure due to the insufficient fixing temperature, the printing productivity is lowered.

On the other hand, the process of calculating the toner loading amount for each page area up to a plurality of pages ahead is shorter than the process of calculating the toner loading amount for each heat generating region of the heating element. However, in this case, the entire page area is set to the fixing temperature according to the largest amount of toner loaded, and there is a possibility that an unnecessarily high fixing temperature is set in a certain area on the page. Therefore, although it is possible to avoid fixing defects while maintaining printing productivity, it is difficult to reduce power consumption.

Therefore, an object of the present invention is to adjust the fixing temperature of the fixing portion so as not to reduce the printing productivity even when the layout processing is performed, and to prevent the fixing failure due to the insufficient fixing temperature. It is to reduce power consumption.

In order to solve the above problems, the present invention is an image forming apparatus that forms a toner image on a recording medium based on input image data, and detects the amount of toner on the page area of the entire page with respect to the image data. The page area loading amount detection unit, the divided area loading amount detecting unit that detects the toner loading amount of the divided area obtained by dividing the page for the image data into a plurality of divided areas, and the divided area loading amount detecting unit, which adjusts the temperature individually for each divided area. The temperature of each divided region of the fixing portion is set based on the detection results of the fixing portion for fixing the toner image on the recording medium, the page area loading amount detecting unit, and the divided region loading amount detecting unit. The control unit has a control unit, and the control unit has a page to be fixed as one page ahead, and the amount of toner in the page area of each image data up to the P1 page destination and the number of pages to the P1 page destination are smaller than P2. It is characterized in that the temperature for each divided region of the fixing portion is set based on the amount of toner loaded for each divided region of each image data up to the page destination.

According to the present invention, even when layout processing is performed, the fixing temperature of the fixing portion is adjusted so as not to reduce the productivity of printing, and consumption is performed while preventing fixing defects due to insufficient fixing temperature. Power can be reduced.

Overview of the image forming apparatus according to the first embodiment Block diagram of the system controller according to the first embodiment Block diagram of the print controller according to the first embodiment Sectional drawing of the image forming apparatus which concerns on Example 1. Schematic cross-sectional view explaining the configuration of the fixing portion of the image forming apparatus according to the first embodiment. The figure explaining the heater composition of the fixing part which concerns on Example 1. (A) and (b) are flowcharts showing the image processing method according to the first embodiment. (A) and (b) are explanatory views about the toner loading amount detection method of the image forming apparatus which concerns on Example 1. (A) and (b) are explanatory views on the toner loading amount detection method of the layout image according to the first embodiment. The figure which shows the relationship between the toner loading amount and fixing temperature which concerns on Example 1. (A) and (b) are flowcharts showing the processing related to the fixing temperature control according to the first embodiment. The figure which shows the relationship between the toner loading amount and the fixing temperature for each page which concerns on Example 1. (A) and (b) are diagrams showing an example of temperature setting according to the first embodiment. The figure which shows an example of the fixing temperature control at the time of printing of the image forming apparatus which concerns on Example 1. Flow chart showing processing related to fixing temperature control according to the second embodiment

Hereinafter, preferred embodiments of the present invention will be described in detail exemplarily with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the following embodiments should be appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions. It is not intended to limit the scope of the invention to those alone.

[Example 1]
<Appearance of copier>
A copying machine, which is an example of the image forming apparatus according to the first embodiment, will be described with reference to FIG. FIG. 1 is a diagram showing an example of the appearance of the copying machine 100 in the first embodiment.

The copying machine 100 as an image forming apparatus includes a printer unit 120, a reader unit 140, an operation unit 160, and the like.

The reader unit 140, which is an image reading means, converts image information into an electric signal by inputting reflected light obtained by exposing and scanning an image of a document by light emission of an illumination lamp into a linear image sensor (CCD sensor). .. The reader unit 140 further converts an electric signal into a luminance signal composed of each color of red (R), green (G), and blue (B), and outputs the luminance signal as image data to the system controller 200 described later.

The manuscript is set in the tray 142 of the manuscript feeder 141. When the user instructs the operation unit 160 to start reading, the system controller 200 sends a document reading instruction to the reader unit 140. Upon receiving this instruction, the reader unit 140 feeds the originals one by one from the tray 142 of the original feeder 141 and performs a document reading operation. The original can also be read by placing it on a platen glass (not shown).

The printer unit 120 is an image forming device that forms a toner image on paper, which is a recording medium, based on image data received from the system controller 200.

The image forming method in this embodiment is an electrophotographic method using a photoconductor such as a photosensitive drum or a photosensitive belt. Further, the printer unit 120 includes a plurality of paper cassettes 121, 122, 123 capable of supporting different paper sizes or different paper orientations. The printed paper is ejected to the output tray 124.

<Copier-System Controller>
The hardware configuration of the copying machine 100 according to the first embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing in detail the hardware configuration of the copying machine 100 of this embodiment, particularly the configuration example of the system controller 200.

The system controller 200 is connected to a reader unit 140 which is an image input device, a printer unit 120 which is an image output device, and a LAN 50, and comprehensively controls the operation of the copying machine 100 and inputs / outputs image information and device information. Take control.

The CPU 201 is a processor (control unit) that controls the entire copying machine, and comprehensively controls access to various connected devices based on a control program or the like stored in the ROM 204. Further, the CPU 201 also comprehensively controls various processes performed inside the system controller 200. The RAM 202 is a system work memory, and is also an image memory for temporarily storing image data and the like. ROM 204 is a boot ROM and stores a system boot program. The HDD 205 is a hard disk drive, and is a non-volatile storage unit that mainly stores information (system software) and image data necessary for starting and operating a computer. These data are not limited to the HDD 205, and may be stored in a storage medium that can store and hold the data even when the power is turned off.

The LANC (LAN controller) 203 is connected to the LAN 50 and inputs / outputs output image data and information related to device control to / from the user PC 60.

The operation unit IF206 outputs the image data to be displayed on the operation unit 160 from the system controller 200 to the operation unit 160. Further, it is an interface for outputting the information input from the operation unit 160 by the user of the copying machine to the system controller 200.

The image processing unit 210 has various image processing blocks inside for appropriately generating image data to be printed. As an image processing block, the image processing unit 210 includes an image rotation unit 211, a color conversion unit 212, a halftone processing unit 213, an image scaling unit 214, a compression / expansion unit 215, a RIP unit 216, and a page area loading amount detection unit 217. It has a divided area loading amount detection unit 218 inside. This will be described below.

First, the image rotation unit 211 performs layout processing and processing for rotating the image data according to the orientation of the paper in the paper cassettes 121, 122, 123.

The color conversion unit 212 performs CMYK conversion of RGB data according to the toner color to generate CMYK data. The image data at this stage shows the density in pixel units, and is represented by, for example, 8 BIT of 0 to 255. As a specific value, 0 for each color indicates that toner is not used, and the density increases as the value increases, and 255 means the maximum density for each color.

The halftone processing unit 213 performs halftone processing on the data of each CMYK color output from the color conversion unit 212. As a specific configuration of the halftone processing unit, there are those by screen processing and those by error diffusion processing. The screen processing uses a plurality of predetermined dither matrices and input image data to convert them into N values. Further, in the error diffusion processing, the input image data is compared with a predetermined threshold value to be converted into an N value, and the difference between the input image data and the threshold value at that time is converted into an N value for the surrounding pixels. It is a process of spreading.

The image scaling unit 214 performs scaling processing such as image enlargement / reduction on RGB image data. The variable magnification can be set from 25% to 400% in 1% increments. Further, by repeatedly inputting the scaled RGB image data to the image scaling unit 214, the scaled processing can be further performed, and the scaled processing is appropriately executed according to the layout processing content.

The compression / decompression unit 215 compresses the multi-valued image data into JPEG, the binary image data into JBIG, MMR, MH, etc., and further decompresses the compressed image data as necessary. Basically, the image data stored in the HDD 205 is compressed before being stored, and the image data read from the HDD 205 is decompressed. Further, in the case of a lossy compression method such as JPEG, the image data deteriorates as the compression is repeated, so it is desirable that the number of compressions is small.

The RIP unit 216 expands the image data (PDL code) received from the user PC 60 via the LAN 50 into raster image data that can be printed, and outputs it as RGB data for each pixel.

The page area loading amount detection unit 217 detects the toner loading amount of the page area, which is an area of the entire page, with respect to the CMYK data before layout processing generated by the color conversion unit 212. This detection process outputs one detection result for the entire page, and a specific method for detecting the amount of toner loaded will be described later.

The divided area loading amount detection unit 218 detects the toner loading amount of the divided area in which the page is divided into a plurality of divided areas for each divided area with respect to the CMYK data after the layout processing. This detection process outputs the detection result for each divided area in which the page is divided into a plurality of divided areas, and a specific method for detecting the amount of toner loaded in each divided area will be described later.

When the toner loading amount detection by the page area loading amount detecting unit 217 or the divided area loading amount detecting unit 218 is completed, the toner loading amount information of the processed image data is held in each detection unit. The toner loading amount information held in each detection unit is read out by the CPU 201.

Next, the reader unit IF207 connects to the reader unit 140 and communicates with the CPU mounted on the reader unit 140. Further, the image read by the reader unit 140 is received, and various image processes such as shading correction are executed by using a known technique.

The printer unit IF208 connects to the printer unit 120 and communicates with the CPU mounted on the printer unit 120. In addition to the print instruction, the communication content also includes the toner loading amount detection result detected by the page area loading amount detecting unit 217 or the divided area loading amount detecting unit 218. Although the details will be described later in the printer unit 120, the image forming unit 310 mainly forms an image on a recording medium such as printing paper.

<Copier-Print Controller>
The hardware configuration of the printer unit in the copying machine according to the first embodiment will be described with reference to FIG. FIG. 3 is a block diagram showing in detail a hardware configuration example of the printer unit 120 of this embodiment.

The print controller 300 controls the image forming unit 310 and comprehensively controls the printing operation of the copying machine 100.

The CPU 301 is a processor that controls the entire printer unit 120, and controls the printer unit 120 in an integrated manner based on a control program or the like stored in the ROM 303. The RAM 302 is used for storing a program or as a work memory.

The controller IF 304 is an IF unit for communicating with the printer unit IF 208 in the system controller 200. The information communicated here includes the control signal and image data from the system controller 200, as well as the toner loading amount information detected by the page area loading amount detecting unit 217 or the divided area loading amount detecting unit 218.

The VIDEO IF 305 transfers image data to the scanner unit 24 of the image forming unit 310 in synchronization with the VIDEO synchronization signal. The image data is sent from the system controller 200 via the controller IF304.

The fixing control unit 306 controls the temperature of the fixing unit 31 based on the fixing temperature information calculated from the toner loading amount information received from the system controller 200.

<Copier-Printer section>
The operation of the image forming unit 310 in the printer unit 120 will be described with reference to FIG. FIG. 4 is an example of the image forming unit 310 of the electrophotographic copying machine of this embodiment, and is a cross-sectional view of a tandem copying machine using the intermediate transfer body 28.

The image forming unit 310 drives the exposure according to a desired exposure time, forms an electrostatic latent image, and develops the electrostatic latent image to form a monochromatic toner image. The monochromatic toner images are superposed to form a multicolor toner image, and the multicolor toner image is transferred to the recording medium 11 to fix the multicolor toner image on the recording medium 11.

The photoconductors 22Y, 22M, 22C, and 22K rotate in the counterclockwise direction according to the image forming operation by transmitting the driving force of a drive motor (not shown), and are yellow (Y), magenta (M), and. It is provided for each of the cyan (C) and black (K) colors. Around each photoconductor, a charging means, an exposure means, a developing means, a primary transfer means, and the like acting on the photoconductor are provided.

The injection chargers 23Y, 23M, 23C, and 23K are charged to charge the photoconductors 22Y, 22M, 22C, and 22K for each color of yellow (Y), magenta (M), cyan (C), and black (K). It is a means. Each injection charger 23Y, 23M, 23C, 23K includes sleeves 23YS, 23MS, 23CS, 23KS.

The scanner units 24Y, 24M, 24C, 24K irradiate the photoconductors 22Y, 22M, 22C, 22K with laser light based on image data of a plurality of colors (Y, M, C, K), and the photoconductors 22Y, 22M, 22C. , An exposure means for selectively exposing a 22K surface. By irradiating light based on the image data from the scanner units 24Y, 24M, 24C, 24K, an electrostatic latent image is formed on the photoconductors 22Y, 22M, 22C, 22K.

In the developing devices 26Y, 26M, 26C, 26K, the developing means is yellow (Y), magenta (M), cyan (in order to visualize the electrostatic latent image formed on the photoconductors 22Y, 22M, 22C, 22K). This is a developing means for developing each of the colors C) and black (K). Sleeves 26YS, 26MS, 26CS, and 26KS are provided on each of the developing machines 26Y, 26M, 26C, and 26K. The developing means is a means for developing an electrostatic latent image formed on a photoconductor to form a monochromatic toner image on each photoconductor.

The primary transfer rollers 27Y, 27M, 27C, and 27K are provided at positions facing each other of the photoconductors 22 via the intermediate transfer body 28, and are primary transfers for transferring a monochromatic toner image from each photoconductor 22 to the intermediate transfer body 28. It is a means. The primary transfer means is a means for transferring a monochromatic toner image formed on each photoconductor by each developing means so as to be sequentially superimposed on the intermediate transfer body.

The monochromatic toner images formed on the photoconductors 22Y, 22M, 22C, and 22K of each station are transferred to the primary transfer rollers 27Y, 27M, 27C, and 27K so as to be superimposed on the intermediate transfer body 28. The multicolor toner image superimposed on the intermediate transfer body 28 is conveyed to the secondary transfer roller 29 as the secondary transfer means as the intermediate transfer body 28 rotates. At the same timing, the recording medium 11 is conveyed from the paper cassette 121 to the secondary transfer roller 29. Then, the secondary transfer roller 29 as the secondary transfer means applies an appropriate bias voltage to electrostatically collectively transfer the multicolor toner image on the intermediate transfer body 28 to the recording medium 11.

The fixing unit 31 applies a fixing sleeve 32 for heating the recording medium 11 and a fixing sleeve 32 for pressing the recording medium 11 against the fixing sleeve 32 in order to melt and fix the multicolor toner image transferred to the recording medium 11 on the recording medium 11. A pressure roller 33 is provided. The fixing unit 31 conveys the recording medium 11 holding the multicolor toner image by the fixing sleeve 32 and the pressure roller 33, and applies heat and pressure to fix the toner image on the recording medium 11.

The recording medium 11 on which the toner image is fixed is then discharged to the paper ejection tray 124 by an ejection roller (not shown). Then, the image forming operation is terminated.

<Copier-Fixing part>
Next, the fixing portion 31 will be described with reference to FIG. The fixing portion 31 has a heating member composed of a fixing sleeve 32 and a heater 35 in contact with the inner surface of the fixing sleeve 32. Further, the fixing portion 31 has a pressurizing roller 33 as a pressurizing member (opposing member) that faces the heater 35 via the fixing sleeve 32 and forms a fixing nip portion together with the heater 35.

Here, the heater 35 is held by the holding member 34. The holding member 34 also has a guide function for guiding the rotation of the fixing sleeve 32. The pressurizing roller 33 receives power from a motor (not shown) and rotates in the counterclockwise direction. Then, as the pressure roller 33 rotates, the fixing sleeve 32 also follows and rotates in the arrow direction (clockwise direction).

A thermistor (not shown) is installed on the inner surface of the fixing sleeve 32 as a temperature detecting means. The fixing sleeve 32 is temperature-controlled to a set temperature by calculating the electric power corresponding to the temperature detected by the thermistor by the print controller 300 and supplying the electric power from the external power source to the heater 201. Further, the set temperature is changed according to the amount of toner loaded on the recording medium in this embodiment. Then, the recording medium carrying the toner image is fixed while being sandwiched and conveyed from the direction of the arrow.

<Copier-Heater section>
The configuration of the heater in the fixing portion will be described with reference to FIG. FIG. 6 is a schematic view showing the configuration of the heater 35 of the first embodiment.

FIG. 6 shows a plan view of the heater 35 on the side (referred to as the back surface layer) that does not come into contact with the inner surface of the fixing sleeve 32. The heater 35 is a heating element that generates heat when electric power is supplied. A plurality of heat generating blocks A1 to A7 composed of a pair of a conductor 403 and a heat generating resistor 402 are provided on the back surface layer of the heater 35 in the longitudinal direction of the heater 35 (the width direction orthogonal to the transport direction of the recording medium).

The heater 35 of this embodiment has a total of seven heat generating blocks A1 to A7 in the longitudinal direction of the heater 35. The heat generation region is from the left end of the heat generation block A1 in the figure to the right end of the heat generation block A7 in the figure. In this example, the widths (lengths) of the heat generating blocks A1 to A7 in the longitudinal direction are all the same.

The heat generation blocks A1 to A7 are formed by the heat generation resistors 402a-1 to 402a-7 and the heat generation resistors 402b-1 to 402b-7 formed symmetrically in the lateral direction (conveying direction of the recording medium) of the heater 35. Each is configured. The conductor 403 is divided into seven conductors 403-1 to 403-7 in order to correspond to the seven heat generating blocks A1 to A7.

The electrodes 401-1 to 401-7 are electrodes for supplying electric power to the heat generating blocks A1 to A7 via the conductors 403-1 to 403-7, respectively.

The heater 35 has a configuration in which electric power can be supplied from the back surface layer side. Further, the electric power supplied to at least one heat generating block of the heat generating blocks and the electric power supplied to the other heat generating blocks can be controlled independently. Therefore, each heat generating block has a configuration in which the temperature can be adjusted (adjustment of the amount of heat generated) individually.

In the heater 35 of this embodiment, the temperature of each of the plurality of heat generating blocks provided in the width direction of the recording medium is individually adjusted according to the amount of toner loaded on the recording medium.

<Flowchart showing image processing method>
Next, with reference to FIG. 7, the copy image processing flow in the system controller 200, and the processing contents of the detection of the toner loading amount in the page area and the detection of the toner loading amount in the divided region, which are characteristic in this embodiment, will be described. FIG. 7A is a processing flow on the image reading side in the copy image processing, and FIG. 7B is a processing flow on the image printing side in the copy image processing.

The processing flow of FIGS. 7A and 7B is executed by the CPU 201 which is a control unit and the image processing unit 210 controlled by the CPU 201 according to the program stored in the ROM 204.

In step S701, the reader unit 140 executes an image reading process for reading the image of the original set on the tray 142 of the document feeder 141 or the original set on the platen glass. The read image data is input into the system controller 200 via the reader unit IF207 and temporarily stored in the RAM 202.

Next, in step S702, the image scaling unit 214 performs scaling processing of the image data as needed. Here, "necessary" refers to a case where the size of the input image data is changed to the size of the output image data by scaling, for example, when page aggregation is performed (4in1 or the like). In that case, it is necessary to reduce the input image size, and it is necessary to change the size of the image data by scaling.

Next, in step S703, the color conversion unit 212 performs CMYK conversion of RGB data according to the toner color to generate CMYK data. That is, the color conversion unit 212 performs color processing.

Next, in step S704, the page area loading amount detection unit 217 detects the toner loading amount in the page area. Here, the reason for detecting the amount of toner loaded is that by detecting using the image data before being stored in the HDD 205 which is the storage unit, the image of the page area of a plurality of pages ahead (P1 page ahead) of the print page is detected. This is because the amount of toner loaded can be detected. Considering that the fixing temperature of the fixing part cannot be changed suddenly, the high toner loading amount of the image data of multiple pages ahead (for example, 5 pages ahead) is detected, and the fixing temperature is gradually raised from 5 pages before. , It is possible to avoid fixing defects while maintaining printing productivity.

Next, in step S705, the halftone processing unit 213 performs halftone processing such as binarization by a method by screen processing or a method by error diffusion processing.

Here, the page area loading amount detection method in the copying machine 100 according to the present embodiment will be described in detail with reference to FIG. The toner loading amount means the amount of toner per unit area, and the unit will be described as%. Specifically, when the maximum value of each CMYK color is set to 100%, the toner loading amount of 200% is defined for the pixel when the maximum value is overlapped for two colors. Since each color has a gradation property, a value between 0 and 100% can be taken for each color. For example, in the case of image data in which the four-color toner of CMYK is fully used in the full-color printing mode, the maximum amount of toner is large, and in the case of a monochrome image of K single color, the maximum amount of toner is small.

First, when the page area loading amount detection unit 217 receives the CMYK data, it calculates the required toner loading amount for each pixel. FIG. 8A shows a part of the image data processed by the page area loading amount detection unit 217, the minimum unit represented by 501 represents one pixel, and 502 represents a pixel block in units of 4 × 4 pixels. ing. Further, it is assumed that the numerical value shown in the frame within one pixel of FIG. 8A represents the toner loading amount (%) for each pixel detected by the page area loading amount detecting unit 217.

Subsequently, the page area loading amount detection unit 217 calculates the average value of the toner loading amount in the pixel block in units of 4 × 4 pixel pixel blocks. Here, the reason for calculating the average value in the pixel block is that the temperature required for fixing an image generally depends on the amount of toner within a certain range, not on the amount of toner loaded on each pixel. Is. Note that 503 in FIG. 8B represents a 1-pixel block (502 in FIG. 8A is a pixel block in units of 4 × 4 pixels), and the numerical values described in the frame of the 1-pixel block are in each pixel block. It represents the average value of the toner loading amount of.

Subsequently, the page area loading amount detection unit 217 reaches the maximum value among the average values of all the blocks in the processed image data at the stage when the calculation of the average value of the toner loading amount in the processed pixel block is completed. Is retained as the toner loading amount information of the target page. This is the page area loading amount information which is the page area loading amount detection result. The meaning of this information is the toner loading amount information of the pixel block, which is the darkest toner loading amount on the page. Since this toner loading amount information is one in the page area, it can be calculated without being affected by layout processing such as image scaling and image rotation. If, unlike this embodiment, the toner loading amount in the page area is detected before the scaling process, the toner loading amount similar to that in this embodiment can be changed by changing the size of the pixel block according to the scaling factor. It is possible to detect information. For example, assuming that the pixel block of the same size is 4 × 4 pixels, if the reduction / scaling is 50%, the number of pixels may be 8 × 8 pixels, which is twice the pixel block.

Next, in step S706 of FIG. 7A, a compression process of compressing the CMYK halftone image data is performed by the compression / expansion unit 215. In this embodiment, JBIG is used as the compression method in order to compress the image data after the halftone processing. Unlike this embodiment, JPEG is used when compressing the image data (contone image) before halftone processing.

Next, in step S707, the compressed halftone image data is stored in the HDD 205. Since the HDD 205 generally has a large capacity and the image data is also compressed, it is possible to store a large amount of image data at low cost.

This completes the processing flow on the image reading side in the copy image processing of FIG. 7A. For example, when this processing flow is executed 5 pages ahead of the processing flow on the image printing side, image data for 5 pages is accumulated in the HDD 205. Then, the page area loading amount detection process can calculate the toner loading amount information of the page area 5 pages ahead (P1 page ahead) of the print page.

Next, the processing flow on the image printing side in the copy image processing of FIG. 7B will be described.

In step S711, the image data spooled in the HDD 205 is read out, and the compression / decompression unit 215 performs decompression processing for decompressing the CMYK halftone image data. In this embodiment, JBIG is used as the stretching method in order to stretch the image data after the halftone processing.

Next, in step S712, the image rotation unit 211 performs image rotation processing as necessary. Here, if necessary, for example, when an A4 vertical document is read by the reader unit 140, the printing paper, which is a recording medium, is placed horizontally on the paper cassette. In this case, the read image data needs to be rotated by 90 ° according to the state set in the paper cassette. Further, even when performing page aggregation processing such as 4in1, rotation processing is executed as necessary.

Next, in step S713, a spool process is performed in which the image data processed in step S712 is temporarily stored in the RAM 202. Here, in the step S713, when the layout process such as page aggregation is executed, the image data is stored in the RAM 202 in consideration of the position where the image after the layout process is placed. As an example, in the case of layout processing for performing 4in1 page aggregation, the processing of steps S711 to S713 is performed four times using the image data spooled in the HDD 205 which is the storage unit by the above-mentioned image reading flow for four pages. repeat. Then, in consideration of the position of the image data after the layout processing, the image data is spooled on the RAM 202. This is called imposition processing.

Further, in step S714, the divided area loading amount detecting unit 218 detects the toner loading amount of the divided area in the page using the image data after the imposition processing. Here, the reason why the divided area loading amount is detected is that the toner loading amount of the divided area in the page and the image area in the area can be matched by detecting using the image data after the imposition processing. This is because the loading amount can be detected.

The toner loading amount detection method is the same as the method shown in FIG. However, the load amount detection performed in step S714 is a halftone image after the halftone processing in step S704. Therefore, for example, in the case of 1-bit gradation (binarized data), the loading amount is 0% or 100% per color. Further, in the case of 2-bit gradation (quadrature data), the loading amount is 0%, 33%, 67%, and 100% per color. Therefore, the loading amount detection performed in step S714 accurately detects the loading amount by further increasing the pixel block size as compared with the loading amount detection performed in step S705. For example, a pixel block is formed with a size of 32 × 32 or 64 × 64 pixels, and the average value thereof is used as the pixel block loading amount information.

Here, the divided region loading amount detection method in the copying machine 100 according to the present embodiment will be described in detail with reference to FIG.

9 (a) and 9 (b) are examples of 4in1 in which the input image data on page 4 is reduced to 1/4 and rotated by 90 °, respectively, and laid out and output on the output image data on page 1. is there.

FIG. 9A shows a scanned image (image data spooled in the HDD) generated by the image scanning flow shown in FIG. 7A. On the 1st and 4th pages of the scanned image, the characters with 100% toner loading are shown, on the 2nd page, the image with 200% toner loading, and on the 3rd page, the image with 150% toner loading is shown. It is described in. FIG. 9B shows a printed image spooled in the RAM 202 in the imposition process of step S713 of the image printing flow shown in FIG. 7B, and the 4in1 layout is completed.

The division area loading amount detection in step S714 shown in FIG. 7B is executed for the printed image (image data after layout processing) shown in FIG. 9B. At this time, in this embodiment, a plurality of divided regions are provided in the main scanning direction of the printed image (width direction orthogonal to the paper transport direction), and are seven regions A1 to A7 in FIG. 9B. .. These seven divided regions show the same regions as the heat generating blocks A1 to A7 of the heater 35 shown in FIG. Therefore, the divided region loading amount detection is a process of detecting the toner loading amount according to the heat generation blocks A1 to A7 whose temperature can be adjusted individually. For example, in the divided area A1, 100% of the character portion is calculated as the loading amount detection result. Further, in the divided regions A2 to A4, 150% of the image portion having a higher toner loading amount than the character portion is calculated as the loading amount detection result. Further, in the divided regions A5 to A7, 200% of the image portion having the highest toner loading amount is calculated as the loading amount detection result. By detecting the load amount in the divided area using the printed image after the layout processing in this way, it is possible to correctly detect and calculate the load amount information corresponding to the heat generation blocks (divided areas) A1 to A7 of the heater 35. Become.

However, on the other hand, it is difficult to detect a high toner loading amount for each divided region of image data of a plurality of pages ahead (for example, 5 pages ahead). In order to realize the load amount detection of a plurality of page destinations (P1 page destination), it is necessary to execute the spool processing for primary storage of the image data layout-processed in step S713 in the RAM 202 for five pages. However, if such a large amount of image data is stored in the RAM 202, the capacity of the RAM 202 increases, resulting in high cost. Further, if the image is recompressed here, an additional compression / decompression portion is required, which also leads to an increase in cost. Further, when the HDD spool or the like is tried to be executed again, the amount of image data reciprocating between the HDD 205 and the RAM 202 increases, which may put pressure on the memory band of the RAM such as the DRAM and cause a deterioration in performance. Therefore, it is assumed that the divided area loading amount detection information can be stored in the RAM 202 up to P2 pages ahead, which is less than the number of pages up to P1 pages ahead of the page area loading amount detection information. In this embodiment, it is assumed that the divided area loading amount detection information can be stored in the RAM 202 for only two pages.

In addition to the user-instructed settings, the layout process determines the processing content according to the orientation of the printing paper stored in the cassette. Therefore, the process of detecting the amount of toner in the divided region as in step S714 is executed not on the image reading side but on the image printing side in the subsequent stage in the image processing flow. Further, by doing so, even in the case of so-called BOX printing in which the image spooled in the HDD is printed according to the instruction from the operation unit 160, the layout can be performed in the same processing flow as the image printing side flow at the time of copying. ..

In step S715 shown in FIG. 7B, print image data is transmitted to the print controller 300 via the printer unit IF208 shown in FIG.

This completes the processing flow on the image printing side in the copy image processing of FIG. 7B. If the print image processing is performed from the user PC 60 instead of the copy image processing, the image reading processing of S701 is replaced with the raster image data generation processing using the RIP unit 216. After that, the processing flow is the same as the copy image processing.

Further, by separating the reading side and the printing side by the HDD spool as in this embodiment, it is possible to make the reading operation by the reader unit 140 and the printing operation by the printer unit 120 asynchronous. This enables reading / printing operations at different speeds and reading / printing operations with page differences.

<Calculation method of fixing temperature based on the amount of toner loaded>
Next, a method of calculating the minimum fixing temperature required for fixing the output image data will be described with reference to FIG.

As described above, the toner loading amount means the amount of toner per unit area on the image. In order to fix the toner without fixing defects, it is necessary to set the temperature of the fixing portion to a fixing temperature at which the maximum value of the toner loading amount in the target region can be surely fixed.

Since the maximum toner loading amount differs depending on the image data to be printed, the fixing temperature required for fixing also differs for each image data, and the larger the maximum toner loading amount, the higher the fixing temperature required for fixing.

FIG. 10 is a diagram showing the relationship between the toner loading amount and the fixing temperature of the copying machine 100 according to this embodiment. In FIG. 10, the horizontal axis represents the amount of toner loaded, and the vertical axis represents the fixing temperature required for fixing.

From FIG. 10, for example, when the detection result by the page area loading amount detecting unit or the divided area loading amount detecting unit is 200%, the minimum temperature required for fixing is T1, and when the detection result is 100%, the target area is fixed. It can be read that the required minimum temperature is T5.

If the temperature of the heater 35 in the fixing portion is raised to a temperature at which the maximum toner loading amount appearing on the printed page can be fixed, problems such as poor fixing will not occur in the entire image. Therefore, it is possible to obtain the minimum temperature required for fixing the output page based on the toner loading amount information detected by each of the loading amount detecting units described above.

Since the relationship shown in the graph of FIG. 10 is used for temperature control of the fixing portion, it is stored in the RAM 302 or the like in the form of a lookup table, for example. Then, the CPU 304 of the print controller 300 executes the conversion to the fixing temperature based on the toner loading amount information received from the system controller 200. Then, the temperature control of the fixing unit 31 is executed via the fixing control unit 306. This conversion process is executed for each divided region (for each of the heat generating blocks A1 to A7 of the heater) if the amount is on the divided region.

<Fixing temperature control based on toner loading amount detection result>
A fixing temperature control process using the toner loading amount detection result in the copying machine 100 according to the present embodiment will be described with reference to FIG.

FIG. 11A shows a process executed under the control of the CPU 201 of the system controller 200 according to the program stored in the ROM 204. Further, FIG. 11B shows a process executed under the control of the CPU 301 of the print controller 300 according to the program stored in the ROM 303.

First, a process executed under the control of the CPU 201 of the system controller 200 will be described with reference to FIG. 11A.

The page in the description of the flowchart shown in FIG. 11 is the image data of one page to be output, and when layout processing such as page aggregation is performed, it is interpreted as the image data after the layout processing.

In step S1101, the CPU 201 receives the copy job input from the reader unit 140. Then, in step S1102, the image reading flow shown in FIG. 7A is executed. In the copying machine 100 according to the present embodiment, the temperature of the fixing portion cannot be changed abruptly. Therefore, in order to control the temperature of the fixing portion without reducing the productivity, the page to be fixed several pages ahead. It is necessary to detect the amount of toner on the surface in advance.

Here, for the sake of simplification of the description, the copying machine 100 will be described as a copying machine 100 in which it is necessary to detect in advance the amount of toner on the page to be fixed after one page and the page to be fixed after five pages. Further, immediately after the start of printing, if the temperature of the fixing portion is controlled after detecting the amount of toner applied, the printing instruction from the user cannot be immediately responded and the productivity drops. Therefore, here, the fixing temperature is not controlled up to the 4th page of the printing start, the maximum toner loading amount that can be considered as the copying machine 100 is controlled to the fixing temperature that can be fixed, and the toner loading amount is calculated from the image data on the 5th page of the printing start. This will be described as a copying machine 100 that detects and controls the temperature.

In step S1103, the CPU 201 determines whether the page to be image-processed is the Nth page or later on which the fixing temperature control control is started, or, here, the fifth page or later. If the page to be image-processed in step S1103 is the fifth page or later on which the fixing temperature control is started, the process proceeds to step S1104.

In step S1104, the page area loading amount information of the target page to be output is calculated by using the page area loading amount detecting unit 217 in this embodiment. Here, for example, in the case of a 4in1 layout in the latter stage, the page area loading amount of the first page on which the page area loading amount information of the highest toner loading amount is printed among the four image data read by the reader unit 140. Calculate as information. Here, it is assumed that the page area loading amount information can be calculated from the printed page to the P1 page ahead. Specifically, it is possible to calculate up to 5 pages ahead.

In step S1105, the CPU 201 notifies the CPU 301 of the print controller 300 of the page area loading amount information of the target page calculated in step S1104 through the printer unit IF208.

In step S1106, the CPU 201 determines whether to start printing. For example, in the case of a 4in1 layout, printing cannot be started until the reading of 4 pages is completed, so the process returns to S1102. If printing is possible, the process proceeds to S1107.

In step S1107, the image printing flow shown in FIG. 7B is executed. In the copying machine 100 according to the present embodiment, the temperature of the fixing portion cannot be changed abruptly. Therefore, in order to control the temperature of the fixing portion without reducing the productivity, the page to be fixed several pages ahead. It is necessary to detect the amount of toner on the surface in advance.

In step S1108, similarly to S1103, the CPU 201 determines whether the page to be image-processed is the Nth page or later on which the fixing temperature control is started, or, here, the fifth page or later. If the page to be image-processed in step S1108 is the fifth page or later on which the fixing temperature control is started, the process proceeds to step S1109.

In step S1109, the divided area loading amount information of the target page to be output is calculated by using the divided area loading amount detecting unit 218 in this embodiment. Here, for example, when the target page is laid out in 4in1, the divided area loading amount information is calculated for each divided area (for each of the heat generating blocks A1 to A7 of the heater) for the image data after the layout. In this calculation process, as described above, it is difficult to calculate the page ahead of the print page (up to P1 page ahead) due to the capacity limitation of the RAM 202, as compared with the calculation of the page area loading amount information. Here, it is assumed that the process of calculating the divided area loading amount information can calculate up to P2 page ahead, which is less than the number of pages up to P1 page ahead. Specifically, it is possible to calculate up to two pages ahead.

In step S1110, the CPU 201 notifies the CPU 301 of the print controller 300 of the divided area loading amount information of the target page calculated in step S1109 through the printer unit IF208.

In step S1111, the CPU 201 determines whether to end printing. If the copy job has the next page, the process returns to S1102. If there is no next page, this flowchart ends.

Next, a process executed under the control of the CPU 301 of the print controller 300 will be described with reference to FIG. 11B.

In step S1121, the CPU 301 waits for a print instruction from the system controller 200. If there is a print instruction from the system controller 200, the process proceeds to step S1122.

In step S1122, in order to print the first four pages without reducing productivity, the fixing control unit 306 sets the temperature of each heater in the fixing unit to the temperature Tmax at which the maximum toner loading amount can be fixed (fixing temperature T1 in FIG. 10). ) To start printing.

In step S1123, the system controller 200 waits for the reception of the toner loading amount information necessary for adjusting the fixing temperature of the target page. When the toner loading amount information is received from the system controller 200 in step S1123, the process proceeds to step S1124. The toner loading amount information received here is both the page area loading amount detection result calculated in step S705 of FIG. 7A and the divided area loading amount detection result calculated in step S714 of FIG. 7B. .. The page area loading amount detection result is the page area loading amount information up to 5 pages ahead (P1 page ahead) with the page to be fixed as one page ahead. The divided area loading amount detection result is the divided area loading amount information up to two pages ahead (P2 page ahead) with the page to be fixed as one page ahead.

In step S1124, the fixing control unit 306 displays the page of the maximum toner loading amount (maximum fixing temperature) from the page area loading amount information up to 5 pages ahead and the divided area loading amount information up to 2 pages ahead that have already been notified. Use as a control target page.

In step S1125, the temperature of the fixing portion is controlled in consideration of the current fixing temperature and the fixing temperature of the control target page determined in step S1124. Specifically, if necessary to reach the target temperature by the control target page, the temperature of the fixing portion is gradually raised over a plurality of pages. Alternatively, if it is possible to lower the fixing temperature with respect to the target temperature, control is performed to lower the temperature. The control of step S1124 and step S1125 will be described in detail later with reference to FIGS. 12 and 13.

It should be noted that step S1124 and step S1125 are executed for each divided region (heat generation blocks A1 to A7 of the heater 35) in which the fixing temperature can be individually controlled. That is, the control for raising or lowering the fixing temperature is individually executed for each of the heat generating blocks A1 to A7 of the heater 35 corresponding to the divided region.

In step S1126, the CPU 301 determines whether the page has ended, and if the page has not ended, the process from step S1123 is repeated.

<Temperature control of fixing part>
FIG. 12 is a table showing the printed page in this embodiment, the amount of information on the printed page, and the minimum temperature required for fixing the printed page. In this embodiment, 15 pages shown in FIG. 12 will be printed, and a specific temperature control of the fixing portion will be described.

The horizontal axis of FIG. 12 represents the number of printed pages, and the vertical axis represents the divided area IDs (heat generating blocks A1 to A7 of the heater) for each printed page. Further, each numerical value at which the divided area ID and the number of printed pages intersect indicates the toner loading amount information of the divided area of the page in%, and the numerical value in parentheses indicates the minimum temperature required for fixing. .. For example, on the first page of the divided region A1, the toner loading amount information is 100%, and the minimum temperature required for fixing the toner is T5.

In the copying machine 100 in this embodiment, the relationship between the toner loading amount and the minimum temperature required for fixing is as shown in FIG. Therefore, the temperature required for fixing an image with a toner loading amount of 200% is T1, the temperature required for fixing an image with a toner loading amount of 150% is T3, and an image with a toner loading amount of 100% is fixed. Let T5 be the temperature required for.

Ideally, it is desirable that each divided region of each page can be fixed at the temperature shown in FIG. However, in order to print without reducing productivity, there is a limit to the amount by which the temperature of the fixing portion can be changed between pages. In this embodiment, it is assumed that the temperature in five stages of T1 to T5 can be changed by only one stage between each page. Therefore, the temperature change from T5 to T3 cannot be carried out in one page, and it is necessary to change the temperature stepwise over a plurality of pages such as T5-T4-T3. Therefore, the actual temperature control is different from the temperature shown in FIG.

FIG. 13 shows an example of temperature control in this embodiment. The table on the left side of FIG. 13A shows the toner loading amount information in the state before the start of printing on the 10th page shown in FIG. At this time, since the divided area loading amount detection result is calculated up to P2 page ahead (here, 2 pages ahead), the toner loading amount information of each of the divided areas A1 to A7 is displayed on the 10th and 11th pages as shown in the figure. And the minimum temperature required for fixing has been calculated. On the other hand, the page area loading amount detection result is calculated up to P1 page destination (here, 5 page destination), which is larger than the number of pages up to P2 page destination. Therefore, as shown in the figure, from the 12th page to the 14th page, the toner loading amount information in the page area and the minimum temperature required for fixing are calculated. The toner loading amount information in this page area is the information on the toner loading amount that is the darkest (requires the highest temperature) in the page, and in this embodiment, in determining the fixing temperature of the divided regions A1 to A7. This is information that each area refers to in common.

The temperature determination result on the 10th page at this time is shown as a set value on the right side of FIG. 13 (a). In the table on the left side of FIG. 13A, the temperature of the divided area A3 and the divided area A4 on the 10th page, which is one page ahead, is T5, but the divided area A3 and the divided area on the 11th page, which is two pages ahead. Since the temperature of A4 is T3, the temperature T3 is the control target. Therefore, when printing the 10th page, the temperature determination result controls the temperature of the divided region A3 and the divided region A4 on the 10th page from T5 to T4 as shown in the table on the right side of FIG. 13 (a). .. The temperature T3 of the page area of the 12th page, which is 3 pages ahead, is the control target for the other divided areas on the 10th page, but since the temperature can still be T5, it is T5. This is because if the temperature is raised by one step at the time of the eleventh page, which is two pages ahead, the temperature can be further raised by one step at the time of the twelfth page, which is three pages ahead, and the temperature can be controlled to T3, which is the target temperature. Is. Therefore, at the time of the 10th page, the temperature of the divided regions A3 and A4 is controlled from T5 to T4, and the temperature of the other divided regions can still be T5, so that the temperature is T5.

Next, the table on the left side of FIG. 13B shows the toner loading amount information in the state before the start of printing on the 11th page shown in FIG. The temperature determination result on the 11th page at this time is shown on the right side of FIG. 13 (b). In the table on the left side of FIG. 13B, the temperature of the divided area A3 and the divided area A4 on the 11th page, which is one page ahead, is T3, and the divided area A3 and the divided area on the 10th page which are currently fixed are set. Since the temperature of A4 is T4, the temperature T3 is the control target. Therefore, when printing the 11th page, the temperature determination result controls the temperature of the divided region A3 and the divided region A4 from T4 to T3 as shown in the table on the right side of FIG. 13B. The temperature T3 of the page area of the 14th page, which is 4 pages ahead, is the control target for the other divided areas on the 11th page, but the temperature can still be T5, so the temperature is T5. This is because if the temperature is raised by one step at the time of the 13th page, which is 3 pages ahead, the temperature can be further raised by 1 step at the time of the 14th page, which is 4 pages ahead, and the temperature can be controlled to T3, which is the target temperature. Is. Therefore, at the time of the 11th page, the temperature of the divided regions A3 and A4 is controlled from T4 to T3, and the temperature of the other divided regions can still be T5, so that the temperature is T5.

Here, if the temperature is controlled using only the page area loading amount information, in FIG. 13A, the temperature T3 two pages ahead (11th page) is the control target in all areas, and all areas are set. It is controlled by the temperature T4. Similarly, in FIG. 13B, the temperature T3 one page ahead (11th page) is the control target in all regions, and all regions are controlled by the temperature T3. Therefore, the effect of reducing the power consumption of the fixing portion by temperature control is reduced.

On the other hand, if the temperature is controlled using only the divided region loading amount information, the toner loading amount 3 pages ahead (12th page) cannot be grasped. Therefore, in FIG. 13A, the amount of toner loaded on the 12th page cannot be grasped, and for example, when the temperature rises in two or more stages in regions other than the divided regions A3 and A4, the temperature cannot be controlled stepwise in advance. .. Therefore, in order to prevent fixing failure due to insufficient fixing temperature, it is necessary to wait until the region rises to the maximum temperature. The same applies to FIG. 13B, and the toner loading amount cannot be grasped on the 13th page, which is 3 pages ahead. Similarly, when the temperature rises in two or more stages, the temperature cannot be controlled stepwise in advance. Therefore, in order to prevent fixing failure due to insufficient fixing temperature, it is necessary to wait until the region rises to the maximum temperature. Therefore, the productivity of the fixing portion by temperature control is lowered.

FIG. 14 shows the transition of the fixing temperature in this example. FIG. 14 shows the transition of the fixing temperature of the divided region A7 when printing the 15 pages shown in FIG. 12 as an example. The horizontal axis of FIG. 14 represents the number of printed pages, and the vertical axis represents the fixing temperature in the divided region A7.

As a characteristic effect in this embodiment, since the page area loading amount detection result can be grasped up to 5 pages ahead, the 9th to 12th pages can be set to the minimum temperature T5. Further, since the result of detecting the amount of the divided area is also used for temperature control, the fixing temperature of the divided area A7 can be set without being affected by the toner amount information of the areas such as the divided areas A3 and A4 on the 11th and 12th pages. The 11th and subsequent pages can be kept to the minimum necessary.

By performing the above control, even when the layout process is performed, the fixing temperature is adjusted for each divided region (for each heating element of the fixing portion) without reducing the printing productivity, and the fixing temperature is insufficient. It is possible to reduce the power consumption while preventing the fixing failure due to the above.

As described above, by using both the page area loading amount detection and the divided area loading amount detection, the fixing temperature for each divided area (heat generation area of the fixing portion) is appropriately performed even when the layout processing is performed. Can be adjusted. Therefore, it is possible to provide an image forming apparatus capable of power saving control while guaranteeing the image of the image data to be output.

[Example 2]
In the first embodiment, a method of constantly executing the page area loading amount detection process and the divided area loading amount detection process for each page when the control of the fixing temperature is started has been described. In the second embodiment, a method of constantly executing the page area loading amount detection process for each page and executing the divided area loading amount detection process as needed will be described.

The configuration of the image forming apparatus, the image processing flow, and the toner loading amount detection processing contents in this embodiment are the same as those in FIGS. 1 to 10 of Example 1, and thus are omitted.

Although the control flow is shown in FIG. 11A of the first embodiment, the detailed control contents are different in the present embodiment in some steps in the flow. In this embodiment, only the difference from the first embodiment will be described.

FIG. 15 describes a fixing temperature control process using the toner loading amount detection result of the copying machine 100 in the second embodiment. Note that FIG. 15 shows a process executed under the control of the CPU 201 of the system controller 200 according to the program stored in the ROM 204. Further, the process executed under the control of the CPU 301 of the print controller 300 is the same as in FIG. 11B, and thus is omitted.

In FIG. 15, the processes from step S1501 to step S1508 are the same as those from step S1101 to step S1108 in FIG. 11A.

In step S1509, the CPU 201 determines whether or not the page area loading amount detection result is equal to or greater than the threshold value. This page area loading amount detection result is the page area loading amount detection result calculated in step S1504. The page area loading amount detection process is executed several pages ahead of the divided area loading amount detection process, but the reference here is the same as the page for which the divided area loading amount is to be calculated in step S1510. This is the result of the page area loading amount detection process of the page.

Further, the threshold value in step 1509 is determined based on the lower limit of the setting range of the fixing temperature in the fixing unit 31, and is the value of the toner loading amount that can be fixed at the lowest temperature in the fixing temperature control. In this embodiment, since T5 shown in FIG. 10 is the minimum temperature in the fixing temperature control, the threshold value is 100%, which is the value of the toner loading amount. This threshold basically changes according to the relationship between the amount of toner loaded and the fixing temperature.

In this embodiment, whether or not the threshold value or more indicates whether or not the maximum toner loading amount in the page area is 100% or more. Therefore, if the page area loading amount information is less than 100%, it can be inferred that the divided area loading amount information is less than 100% in all the divided areas A1 to A7 of the page. In that case, since it can be inferred that the page can be fixed even at the lowest temperature (T5) in all the divided regions, the divided region loading amount calculation control in step S1510 and the print controller 300 in step S1511 to the CPU 301 Notifications can be omitted. In other words, it is possible to control to the minimum temperature (T5) without executing the detection of the toner loading amount in the divided region by the divided region loading amount detecting unit 218.

Therefore, if the page area loading amount detection result is less than the threshold value (NO) in step S1509, the process proceeds to step S1512, and if the page area loading amount detection result is equal to or greater than the threshold value (YES) in step S1509, the process proceeds to step S1510.

In FIG. 15, the processes from step S1510 to step S1512 are the same as the processes from steps S1109 to S1111 in FIG. 11A.

As described above, the divided area loading amount detection process is executed as necessary based on the page area loading amount detection result. Specifically, when the toner loading amount of the page area detected by the page area loading amount detecting unit is less than the threshold value, the divided area loading amount detecting unit does not detect the toner loading amount of the divided area. Even in such a case, as in the first embodiment, the fixing temperature can be adjusted without reducing the printing productivity, and the power consumption can be reduced while preventing the fixing failure due to the insufficient fixing temperature. .. As a result, in the case where the CPU 201 executes the divided area loading amount detection process as a software program, it is possible to speed up the fixing temperature control flow based on the toner loading amount detection result.

[Other Examples]
In the above-described embodiment, the copying machine has been exemplified as the image forming apparatus, but the present invention is not limited to this, and other image forming apparatus such as a printer and a facsimile apparatus, or a combination thereof is combined. It may be another image forming apparatus such as a multifunction device. Further, an image forming apparatus is exemplified in which an intermediate transfer body is used, toner images of each color are sequentially superimposed and transferred to the intermediate transfer body, and the toner images supported on the intermediate transfer body are collectively transferred to a recording medium. , Not limited to this. An image forming apparatus may be used in which a recording medium carrier is used and toner images of each color are sequentially superimposed and transferred onto the recording medium supported on the recording medium carrier. Similar effects can be obtained by applying the present invention to these image forming devices.

A1 to A7 ... Heat generation block (divided area)
31 ... Fixing unit 32 ... Fixing sleeve 33 ... Pressurizing roller 34 ... Holding member 35 ... Heater 100 ... Copier 120 ... Printer unit 140 ... Leader unit 200 ... System controller 201 ... CPU
202 ... RAM
203 ... LANC
204… ROM
205 ... HDD
210 ... Image processing unit 211 ... Image rotation unit 212 ... Color conversion unit 213 ... Halftone processing unit 214 ... Image scaling unit 215 ... Compression / expansion unit 216 ... RIP unit 217 ... Page area loading amount detection unit 218 ... Divided area loading amount Detector 300 ... Print controller 301 ... CPU
302… RAM
303 ... ROM
306 ... Fixing control unit 310 ... Image forming unit 401 ... Electrode 402 ... Heat-generating resistor 403 ... Conductor

Claims (8)

An image forming apparatus that forms a toner image on a recording medium based on input image data.
A page area loading amount detecting unit that detects the toner loading amount of the page area of the entire page with respect to the image data, and
A divided area loading amount detecting unit that detects the toner loading amount of the divided region obtained by dividing the page for the image data into a plurality of divided regions for each divided region.
A fixing portion for fixing the toner image on a recording medium, which can be adjusted to an individual temperature for each divided region, and a fixing portion.
It has a page area loading amount detecting unit and a control unit that sets the temperature of each divided region of the fixing unit based on the detection result of the divided area loading amount detecting unit.
The control unit sets the page to be fixed as one page ahead, and the toner loading amount in the page area of each image data up to P1 page ahead and each image data up to P2 page ahead, which is less than the number of pages up to P1 page ahead. An image forming apparatus characterized in that the temperature of each divided region of the fixing portion is set based on the amount of toner loaded on each divided region. The image forming apparatus according to claim 1, wherein the control unit executes detection by the page area loading amount detecting unit prior to detection by the divided area loading amount detecting unit. The image forming apparatus according to claim 1 or 2, wherein the control unit raises the temperature of each divided region stepwise over a plurality of pages. It has a non-volatile storage unit that stores the input image data.
The control unit executes detection by the page area loading amount detecting unit before storing the image data in the storage unit, stores the image data in the storage unit, and then detects by the divided area loading amount detecting unit. The image forming apparatus according to any one of claims 1 to 3, wherein the image forming apparatus is performed. It has a halftone processing unit that performs halftone processing using the input image data.
The control unit executes the detection by the page area loading amount detection unit on the image data before the halftone processing, and the detection by the divided area loading amount detecting unit on the image data after the halftone processing. The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is executed. The control unit executes the detection by the page area loading amount detecting unit on the image data before the layout processing, and executes the detection by the divided area loading amount detecting unit on the image data after the layout processing. The image forming apparatus according to any one of claims 1 to 5, which is characterized. A claim characterized in that when the toner loading amount of the page area detected by the page area loading amount detecting unit is less than the threshold value, the toner loading amount of the divided area is not detected by the divided area loading amount detecting unit. Item 6. The image forming apparatus according to any one of Items 1 to 6. The image forming apparatus according to claim 7, wherein the threshold value of the toner loading amount is determined based on the lower limit of the setting range of the fixing temperature in the fixing portion.

Images