JP5817269B2 - Image forming apparatus, toner consumption calculation method, and computer program - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus, a toner consumption calculation method, and a computer program for calculating toner consumption.

  In an electrophotographic image forming apparatus that prints a toner image corresponding to image data on a sheet, the amount of toner consumed in each printing is calculated based on the image data. Since there is a correlation between the toner consumption and the number of dots in the toner image, the toner consumption per one dot (toner adhesion amount on the photosensitive member) estimated in advance and the number of dots determined by the image data are used. It is possible to calculate a toner consumption amount per image (strictly speaking, an estimated consumption amount). The calculation result is used for controlling toner supply from the toner bottle to the developing device, for example. The calculated toner consumption is integrated, and when the integrated value exceeds a predetermined value, a maintenance display such as a toner bottle empty display or a waste toner box full display is performed.

By the way, in the electrophotographic process, there is a difference in the toner adhesion amount when developing the electrostatic latent image between the edge portion and the non-edge portion in the image. In general, since a strong edge electric field is generated at the edge portion of the electrostatic latent image, more toner adheres at the edge portion than at the non-edge portion even at the same gradation. Therefore, Patent Document 1 proposes that the edge portion of the image data is detected, the frequency of appearance of the edge portion pixel is counted for each gradation, and the toner consumption is calculated by multiplying the count value by a predetermined coefficient. ing. Japanese Patent Application Laid-Open No. 2004-228561 describes a method of calculating the ratio of edges in the entire image and correcting the toner consumption amount of the entire image according to the ratio.

JP 2006-276422 A JP 2009-169307 A

  It is necessary to determine the toner consumption amount in each printing more accurately. By accurately obtaining the toner consumption, the error of the integrated toner consumption can be reduced, and the reliability of message display based on the integrated toner consumption for the user can be increased. For example, the cumulative number of prints is set based on the durable print number of toner bottles (standard area ratio is used as a reference) even though only images with an area ratio on the paper smaller than the standard value (generally 5%) are printed. ), It is possible to prevent a situation that is inconvenient for the user to request replacement of the toner bottle when it does not exceed.

  In view of such circumstances, an object of the present invention is to provide an apparatus and a method for more accurately obtaining a toner consumption amount in each printing.

An image forming apparatus that achieves the above object is an image forming apparatus capable of switching an operation speed for determining a time required for image formation by an electrophotographic process by specifying a mode, and when forming a toner image corresponding to image data. A counting unit that counts the number of pixels of the image data for each pixel value and for each attribute that distinguishes between edge attribute pixels and non-edge attribute pixels indicated by the attribute information added to the image data; the number of different pixel pixel-value-basis and attribute counted by parts, based on the coefficient determined in said operating speed compatible pixel value by and demographic which is switched by the mode designation, specific pixel values and attributes A calculating unit that calculates another toner consumption amount and calculates the total toner consumption amount as a toner consumption amount in the formation of the toner image.

  According to the present invention, the toner consumption amount is calculated by distinguishing whether it corresponds to an edge and applying a coefficient determined according to the operation speed in units of pixels, so that the toner consumption amount depends on the operation speed. It is possible to reduce an error in calculating the toner consumption amount.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a block diagram illustrating a hardware configuration of the image forming apparatus. FIG. It is a figure which shows the function structure of a printer controller. FIG. 4 is a diagram illustrating a configuration of a main part related to calculation of toner consumption. It is a figure which shows typically the exposure spot corresponding to an edge pixel and a non-edge pixel, respectively. It is a figure which shows qualitatively the relationship between the toner adhesion amount and printing speed of an edge part and a non-edge part. It is a figure which shows qualitatively the printing speed dependence of a toner adhesion characteristic. It is a figure which shows typically the exposure spot corresponding to image quality setting. It is a figure which shows the image quality dependence of a toner adhesion characteristic qualitatively. It is a figure which shows the structure of the count table used for calculation of toner consumption. It is a figure which shows the structure of the coefficient table used for calculation of toner consumption. It is a figure which shows the structure of the coefficient table used for calculation of toner consumption. It is a figure which shows the structure of the coefficient table used for calculation of toner consumption. 6 is a flowchart illustrating a flow of processing for calculating a toner consumption amount. It is a figure which shows the modification of a coefficient table. It is a figure which shows the modification of a coefficient table. It is a figure which shows the modification of a coefficient table.

  A function for calculating the toner consumption based on the image data can be mounted on any image forming apparatus that prints an image by electrophotography. There are many types of electrophotographic image forming apparatuses such as printers, copiers, facsimile machines, and MFPs (multi-functional peripherals). In the following, an MFP having many uses including copying and network printing is taken as an example.

  An image forming apparatus 1 illustrated in FIG. 1 includes a tandem printer engine that forms a color or monochrome image by electrophotography. The printer engine uses four imaging units 11, 12, 13, and 14 to form toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (K) in parallel. be able to. The imaging units 11, 12, 13, and 14 each have one photosensitive drum 15, 16, 17, and 18 as an image carrier, and can be individually attached to and detached from the apparatus main body. In each of the imaging units 11, 12, 13, and 14, devices necessary for forming a toner image, such as a charging charger, a developing device, and a cleaner, are arranged around a cylindrical photosensitive member. The toner of the corresponding color is supplied to the developing device from the toner cartridges 25, 26, 27, and 28 at appropriate times.

  The image forming apparatus 1 is given a print job by a direct operation using the operation panel 35 or an access from an external device (typically a personal computer) (not shown) connected via a network. The print job includes a copy job in which an original image is read by the image scanner 30 and copied. For example, when a print job for forming a color image is given, the image forming apparatus 1 operates as follows.

  The image forming apparatus 1 generates a raster image, which is exposure pattern data for each color of Y, M, C, and K, based on scan image data read from a document or image data given from an external device. In a state where the photoconductor drums 15, 16, 17, and 18 are rotating, the print head 22 irradiates the charged photoconductor with laser light. At this time, the print head 22 controls the light source in accordance with the raster image, thereby performing main scanning for each color on the photosensitive member. An electrostatic latent image is formed on the photoconductor by main scanning and sub-scanning (rotation of the photoconductor). Since the development format is reversal development, the charge of the dot portion to which the toner is to be attached in the electrostatic latent image is less than the charge of the other portion by exposure. The developing units of the imaging units 11, 12, 13, and 14 cause the toner to be attracted to the photoreceptor to form a toner image corresponding to the electrostatic latent image. The formed toner image is primarily transferred to an intermediate transfer belt 23 that is an endless transfer body that moves along the arrangement of the photoreceptors. The order of toner image formation and the order of primary transfer are determined by the arrangement of the imaging units 11, 12, 13, and 14. In this example, the order is Y, M, C, and K from the upstream side. The timings of latent image formation and primary transfer for the four colors are set so that the four color toner images overlap on the intermediate transfer belt 23 in an appropriate positional relationship without being shifted from each other.

  In parallel with the operation of forming four toner images per sheet surface, the sheet P is taken out from the multistage sheet stacker 40 by the pickup roller 41 and conveyed. In some cases, paper is fed from the manual feed tray 48. A one-dot chain line in the drawing indicates a conveyance path of the paper P. The pair of registration rollers 44 temporarily hold the paper and feed it to the secondary transfer position at an appropriate timing. The secondary transfer position is a position where the intermediate transfer belt 23 and the pressure roller 45 face each other so as to form a nip portion. The toner images having the four colors overlapped from the intermediate transfer belt 23 are secondarily transferred onto the sheet P passing through the secondary transfer position. Thereafter, the paper P passes through the inside of the fixing unit 29 and is discharged onto the paper discharge tray 46. When the paper passes through the fixing unit 29, the toner is melted by heating and pressurization, and the toner image is fixed on the paper as a print image.

  In the image forming apparatus 1, an operation speed (referred to as a printing speed) for determining a time required for image formation by a series of electrophotographic processes is variable. The printing speed can be switched to, for example, three levels (large, medium, and small) according to the mode designation by the user. The lower the printing speed, the better the finished image quality, but the higher the printing speed is advantageous from the viewpoint of the time required for image formation. The default printing speed is “medium”. A mode with a low printing speed is designated by a user who wants to obtain a higher quality printed material, and a mode with a large printing speed is designated by a user who wants to obtain a printed material earlier.

  In the image forming apparatus 1, the printing resolution is variable. The resolution can be switched to, for example, three levels (high, medium, low) according to the image quality designation by the user. The default image quality is “medium”. The high resolution mode is set when "High" image quality is specified, the normal mode is set when "Medium" image quality is specified, and the low resolution mode is set when "Low" image quality is specified. .

  As shown in FIG. 2, the image forming apparatus 1 includes a main controller 60 that controls the entire control. The main controller 20 performs predetermined control in response to a user instruction from the operation panel 35 and an operation request from an external device communicating via the communication interface 66. In the copying operation, an image scanner 30 and an ADF (Auto Document Feeder) 31 are controlled. In various printing operations including copying, an instruction is given from the main controller 20 to the engine controller 80 that controls the printer engine 10. Further, a hard disk drive (HDD) as the built-in storage 68 is accessed by the main controller 20 as necessary. The main controller 20 includes a central processing unit (CPU) that executes a control program and various applications, a read only memory (ROM) that stores the control program, and a random access memory (RAM) that is a work area for executing the program. Have. The main controller 20 includes a printer controller 70 as an image generation unit that is a functional element realized by executing a control program.

  As illustrated in FIG. 3, the printer controller 70 includes an analysis unit 71, a rasterization unit 72, and a gradation reproduction unit 73. The printer controller 70 generates raster images D4y, D4m, D4c, and D4k corresponding to the four color toner images for printing the print target data D1. The printer controller 70 receives a scan image from the image scanner 30 as print target data D1 in a copy operation, and receives print target data D1 from the communication interface 66 in network printing and facsimile reception. When printing a document stored in the image forming apparatus 1, print target data D <b> 1 is input from the storage 68 to the printer controller 70.

  When the print job is a network printing job, the analysis unit 71 interprets print target data D1 described in a page description language (PDL), generates intermediate data representing the contents to be rendered, and rasterizes the data. Delivered to part 72. That is, the intermediate data is the data D2 output by the analysis unit 71 in this case. The contents to be drawn described in PDL are roughly divided into three attributes (types) of “text” representing characters, “graphics” representing figures and lines, and “image” representing raster images. The intermediate data includes information indicating the attribute of the area in the page. On the other hand, when print target data D1 not described in PDL is input as in a copy job or a facsimile reception job, the analysis unit 71 delivers the print target data D1 to the rasterization unit 72 as data D2 substantially as it is. At the same time, the analysis unit 71 extracts a text region and a graphic region from the print target data D1 using a known region discrimination technique, and gives region attribute information DA indicating the result to the rasterization unit 72.

  The rasterizing unit 72 performs color conversion processing from RGB to YMCK on the data D2 delivered from the analyzing unit 71, and multi-value raster images (frames) D3y, D3m, D4m corresponding to each of the four colors of YMCK. D3c and D3k are generated. In addition, the rasterizing unit 72 determines whether the pixel in the region where the region attribute in each raster image D3y, D3m, D3c, D3k corresponds to text or graphic is an edge pixel corresponding to an edge or a non-edge pixel that is not the case. To do. Then, edge attribute information (tag) DEy, DEm, DEc, DEk indicating which pixel is the edge pixel is added to the raster images D3y, D3m, D3c, D3k of the corresponding color. The edge here is a boundary portion between the background and a character or a figure, and a portion where a difference in pixel values between adjacent pixels in the figure is equal to or greater than a threshold value.

  The tone reproduction unit 73 converts the raster images D3y, D3m, D3c, and D3k into raster images D4y, D4m, D4c, and D4k for exposure control by properly using a plurality of tone reproduction methods according to the type of job. . In the present embodiment, the gradation reproduction unit 73 uniformly applies one selected from the three kinds of gradation reproduction methods to the four colors and to the entire image of each color. More specifically, the error diffusion method is applied in the case of a copy operation, and the screen processing (dither method) is applied in the case of a printer operation that prints an electronic document having attribute information. In the case of operation, binarization is applied. However, a plurality of gradation reproduction methods may be applied to one image by using, for example, the error diffusion method and the screen processing separately for each region in the image. Since the print head 22 of the image forming apparatus 1 can increase or decrease the exposure amount for each pixel by one or both of pulse width modulation and light source power control, a raster image D4y generated by applying an error diffusion method or screen processing. , D4m, D4c, and D4k are multi-valued images. The raster images D4y, D4m, D4c, and D4k generated by the gradation reproduction unit 73 are sent to the print head 22 via the engine controller 80. Then, in order to calculate the toner consumption amount of each color in the imaging units 11, 12, 13, and 14 by distinguishing between edge pixels and non-edge pixels, the edge attribute information DEy, DEm, DEc, DEk of each color is sent to the engine controller 80. It is done.

  As shown in FIG. 4, the engine controller 80 includes a CPU 81 as a computer for executing a control program, a RAM 82 as a work area for executing the program, and a CSIC as a non-volatile memory 83 for storing various data including the program. (Customer Specific Integrated Circuit). The CPU 81 controls the operation of various mechanisms constituting the printer engine 10 and calculates the amount of toner consumed by the imaging units 11, 12, 13, and 14 for each printing operation. In calculating the toner consumption amount, a count table CT for counting the number of pixels for each pixel value is provided in the RAM 82, and coefficient tables T1, T2, and T3 (described later) stored in advance in the nonvolatile memory 83 are referred to.

  In calculating the toner consumption amount, the printing speed (process speed) and the image quality setting are taken into consideration. This is because the amount of toner adhering to the photoconductor depends on the rotational speed of the photoconductor and also on the dot density on the photoconductor. The CPU 81 of the engine controller 80 takes in the coefficients to be applied to the calculation from the coefficient tables T1, T2, and T3 according to the printing speed information DS and the image quality setting information DG from the main controller 60. The printing speed information DS is control information indicating the setting state of the printing speed, and the image quality setting information DG is control information indicating the setting state of the image quality.

  The calculation result of the toner consumption calculated for each color is used to control the toner replenishing mechanism 56 that sends toner from the toner cartridge to the developing device. When displaying the toner consumption amount of each printing on the operation panel 35, the calculation result of the toner consumption amount is notified to the main controller 60 responsible for the display control. For example, the integrated toner consumption amount stored in the nonvolatile memory 83 is updated to a value obtained by adding the newly calculated toner consumption amount.

  Hereinafter, the calculation of the toner consumption amount in the image forming apparatus 1 will be described in more detail.

  5A and 5B schematically show an exposure method for distinguishing between edge pixels and non-edge pixels. As shown in FIG. 5A, when the character pattern G1 having a uniform density is reproduced by the error diffusion method, in order to prevent the character from appearing to spread due to excessive toner adhering to the edge, The pixel values of the exposure raster images D4y, D4m, D4c, and D4k are determined so that the area of the exposure spot Se corresponding to the edge pixel is smaller than the area of the exposure spot Sne corresponding to the non-edge pixel. Further, as shown in FIG. 5B, even when the character pattern G2 having a uniform density is reproduced by the screen processing, the area of the exposure spot Se corresponding to the edge pixel corresponds to the non-edge pixel in order to prevent character thickening. It is made smaller than the area of the exposure spot Sne.

  However, the toner adhesion amount on the photosensitive member increases as the exposure area (that is, pixel value) increases, but is not proportional. If the toner consumption amount is simply calculated on the assumption that the toner adhesion amount is proportional to the exposure area, an error occurs between the calculated value and the actual consumption amount. The relationship between the toner adhesion amount and the exposure area differs between edge pixels and non-edge pixels. Therefore, it is necessary to calculate the toner consumption for each pixel value and distinguishing between edge pixels and non-edge pixels.

  As shown in FIG. 5C, when the character pattern G3 having a uniform density is reproduced by binarization, the pixel values of the raster images D4y, D4m, D4c, and D4k are values corresponding to dots (black pixels) or the background. One of the values corresponding to (white pixel). That is, the area of the exposure spot Se corresponding to the edge pixel is equal to the area of the exposure spot Sne corresponding to the non-edge pixel. However, the toner adhesion amount differs between edge pixels and non-edge pixels. Therefore, even in the case of binarization, it is necessary to calculate the toner consumption for each pixel value by distinguishing between edge pixels and non-edge pixels.

  FIG. 6 qualitatively shows the relationship between the toner adhesion amount at the edge portion and the non-edge portion and the printing speed. When reproducing a pattern having a uniform density from the position p1 to the position p2, the toner adhesion amount is substantially equal at the non-edge portion even if the printing speed is different. However, the toner adhesion amount is larger at the edge portion than when the printing speed is low. Therefore, when calculating the toner consumption amount, it is necessary to distinguish between edge pixels and non-edge pixels and to distinguish printing speed.

  FIG. 7 qualitatively shows the printing speed dependence of toner adhesion characteristics. As shown in the figure, the larger the exposure amount per pixel, the larger the toner adhesion amount on the photoreceptor. Then, over the entire range of exposure, the print speed level is higher for “Medium” than for “Large” and more for “Small” than for “Medium”. Toner adheres. Here, the image forming apparatus 1 has an automatic stabilization function, and adjusts the developing bias voltage (Vdc), for example, in order to reduce the influence of the printing speed on the density of the printed image. Thereby, as shown in FIG. 7, the toner adhesion amount corresponding to the maximum exposure amount is set to a predetermined value regardless of the printing speed.

  However, when looking at the toner adhesion amount corresponding to the exposure amount excluding the minimum exposure amount and the maximum exposure amount, the value of the toner adhesion amount varies depending on the printing speed. Therefore, in order to calculate the toner consumption more accurately, it is necessary to reflect the printing speed during printing in the calculation.

  FIGS. 8A and 8B schematically show exposure spots corresponding to image quality settings. As shown in FIG. 8A, in the case of normal image quality (“medium” of the above-mentioned image quality), the area of the exposure spot Se corresponding to the edge pixel is the area of the exposure spot Sne corresponding to the non-edge pixel in order to prevent character thickening. Is made smaller. As shown in FIG. 8B, the exposure spot Sne corresponding to the non-edge pixel has an area of the exposure spot Se corresponding to the edge pixel in order to prevent character thickening even in the case of high definition (“high” in the above-described image quality). Is smaller than the area. That is, the toner adhesion amount per unit area differs between the edge portion and the non-edge portion. Therefore, it is necessary to calculate the toner consumption amount by distinguishing between edge pixels and non-edge pixels.

  FIG. 9 qualitatively shows the image quality dependence of the toner adhesion characteristics. As shown in the figure, the larger the exposure amount per pixel, the larger the toner adhesion amount on the photoreceptor. Over the entire exposure range, more toner is stored in the “medium” case than in the “low” image quality setting compared to the “medium” case. Adhere to. That is, as the resolution increases and the pixel density increases, more toner adheres. Therefore, in order to calculate the toner consumption more accurately, it is necessary to calculate for each image quality setting.

  FIG. 10 shows the configuration of the count table CT used for calculating the toner consumption. The count table CT is a memory area for counting the number of pixels for each tone reproduction method, for each pixel value, and for each edge attribute for each YMCK raster image D4y, D4m, D4c, D4k indicating the exposure amount for each pixel. is there. In the figure, the pixel values (exposure gradation) of the raster images D4y, D4m, D4c, and D4k are 64 levels from 0 to 63. However, the present invention is not limited to this, and the number of exposure gradations may be more or less than 64. In addition, when only one gradation reproduction method is used according to the job type (copy, print, facsimile), an area for storing the count value related to another gradation reproduction method can be omitted.

The toner consumption amount (Q) for one image printed on the paper is the toner adhesion amount (q ₁ to 1 pixel) for each of a plurality of count values (N _{1 to} N _x ) stored in the count table CT. q _x ) is the sum (N ₁ q ₁ + N2q2... N _x-1 q _x-1 + N _x q _x ) obtained by adding the products obtained by multiplication. The toner adhesion amount for one pixel is determined for each type of pixel counted separately. Specifically, the toner adhesion amount for one pixel is set to a basic toner adhesion amount predetermined according to pixel value and edge attribute (edge pixel or non-edge pixel). Is a product multiplied by a correction coefficient that reflects. This correction coefficient is determined in advance by experiment or calculation based on the characteristics shown in FIGS. 7 and 9, and is stored in the engine controller 80 as data of the coefficient tables T1, T2, and T3.

  The coefficient table T1 shown in FIG. 11 has correction coefficients when the error diffusion method is applied when generating the raster images D4y, D4m, D4c, and D4k. Although most of them are omitted in the drawing, a total of 1152 correction coefficients are stored. For each of the 128 pixel types classified into edge pixels and non-edge pixels for each of the 64 pixel values from 0 to 63, three cases are classified according to the printing speed. There are three cases according to image quality.

  The coefficient table T2 shown in FIG. 12 has correction coefficients when screen processing is applied when generating raster images D4y, D4m, D4c, and D4k. Although most of them are omitted in the drawing, a total of 1152 correction coefficients are also stored in the coefficient table T2.

  The coefficient table T3 shown in FIG. 13 has correction coefficients when binarization is applied when generating raster images D4y, D4m, D4c, and D4k. In the binarization, the pixel values are not distinguished, and each of the two pixel types classified into the edge pixel and the non-edge pixel is divided into three cases according to the printing speed. Depending on the case, there are three cases. A total of 18 correction coefficients are stored in the coefficient table T2.

  In each of the coefficient tables T1, T2, and T3, a plurality of correction coefficients may include correction coefficients having the same value. In addition, the correction coefficient values may or may not be partially shared between the coefficient tables T1, T2, and T3.

  FIG. 14 shows the flow of processing for calculating the toner consumption.

  The CPU 81 of the engine controller 80 takes in the image data sent from the main controller 60 (S10). That is, raster images D4y, D4m, D4c, and D4k are captured in the case of color printing, and raster images of the printing color (generally black) are captured in the case of monochrome printing. Then, the CPU 81 determines whether each pixel of the captured raster image is an edge pixel or a non-edge pixel based on the edge attribute information DEy, DEm, DEc, DEk (S11), and distinguishes between the edge pixel and the non-edge pixel. The number of pixels is counted for each pixel value (S12). The count table CT is used at this time. When executing these steps S11 and S12, the CPU 81 operates as a counting unit.

Next, the CPU 81 determines the job type notified from the main controller 60 based on the job type.
The gradation reproduction method applied to the generation of the raster image is determined (S13). Subsequently, the CPU 81 takes in the printing speed information DS from the main controller 60 and determines which of the above three-stage speed levels the current printing speed corresponds to (S14), and based on the image quality setting information DG. It is determined whether the image quality set in the current printing corresponds to one of the three types of image quality (high, medium, low) described above (S15). The operation in step S14 is an operation as a speed determination unit, and the operation in step S15 is an operation as an image quality determination unit.

  In accordance with the gradation reproduction method, speed, and image quality determined in steps S13 to S15, the CPU 81 calculates a correction coefficient corresponding to each count value of the number of pixels for each pixel value and each edge attribute from the coefficient tables T1, T2, and T3. Selected (S16). Then, the CPU 81 multiplies the count value of each pixel number, the basic toner adhesion amount for one pixel corresponding thereto, and the selected correction coefficient, and adds the obtained products to obtain the toner consumption amount for one image ( S17).

  FIGS. 15, 16 and 17 show coefficient tables T1b, T2b and T3b used in the modified example of the toner consumption calculation. These coefficient tables T1b, T2b, and T3b are used when calculating the toner consumption amount that is not classified according to the image quality in the calculation of the toner consumption amount. If the influence of the image quality setting on the toner adhesion is slight, the classification according to the image quality can be omitted.

  The coefficient table T1b in FIG. 15 has correction coefficients when the error diffusion method is applied when generating the raster images D4y, D4m, D4c, and D4k, and the coefficient table T2b in FIG. 16 shows correction coefficients when the screen processing is applied. Have. In the coefficient tables T1b and T2b, for each of the 128 pixel types classified into edge pixels and non-edge pixels for each of 64 pixel values from 0 to 63, there are three cases according to the printing speed. Thus, 384 correction coefficients are stored in each of the coefficient tables T1b and T2b. The coefficient table T3b in FIG. 17 has correction coefficients when binarization is applied. In the coefficient table T3b, for each of the two pixel types classified into edge pixels and non-edge pixels, three cases are classified according to the printing speed, and a total of six correction coefficients are stored.

  According to the above embodiment, the toner consumption amount is more accurately calculated using the correction coefficient corresponding to the printing speed, and toner is replenished based on the calculation result, so that the toner density in the developing device is stabilized. be able to. The error in the accumulated toner consumption can be reduced, and the reliability of the message display based on the accumulated toner consumption for the user can be improved. That is, it is inconvenient for the user to request replacement of the toner cartridge when the cumulative number of printed sheets does not exceed the durable print number of the toner cartridge even though only the image whose area ratio on the paper is smaller than the standard value is printed. The occurrence of unusual situations can be prevented.

  In the above-described embodiment, the basic toner adhesion amount is multiplied by the correction coefficient indicated by the coefficient tables T1, T2, T3, T1b, T2b, and T3b to calculate the toner adhesion amount for one pixel. The stored toner adhesion amount is stored as a coefficient in the coefficient tables T1, T2, T3, T1b, T2b, and T3b. The coefficient is multiplied by the count value of the number of pixels, and the total sum of the obtained products is stored for one image. You may make it calculate as a toner consumption.

  The coefficient tables T1, T2, T3, T1b, T2b, and T3b have been described as commonly applied to the four colors. However, when there is a significant difference in toner adhesion characteristics among the four colors, each of the four colors is used. On the other hand, coefficient tables T1, T2, T3, T1b, T2b, and T3b may be prepared. A correction coefficient may be shared for colors having similar toner adhesion characteristics, and correction coefficients may be individually determined for the remaining colors.

  The number of printing speed categories is not limited to three as illustrated, but may be two or more. The number of image quality categories is not limited to three as illustrated, but may be two or more.

1 Image forming apparatus D4y, D4m, D4c, D4k Raster image (image data)
81 CPU (counter, calculator)
DS Print speed information DG Image quality setting information 70 Printer controller (image generator)
T1, T2, T3, T1b, T2b, T3b coefficient table

Claims (5)

An image forming apparatus capable of switching an operation speed for determining a time required for image formation by an electrophotographic process by specifying a mode ,
When forming a toner image corresponding to the image data, the image data is classified according to the pixel value and the attribute that distinguishes the edge attribute pixel and the non-edge attribute pixel indicated by the attribute information added to the image data. A counting unit for counting the number of pixels;
Wherein the number of counted pixel value by and demographic of the pixel by counting section, based on the coefficient determined in said operating speed compatible pixel value by and demographic which is switched by a mode designation, the pixel-value-basis An image forming apparatus comprising: a calculation unit that calculates a toner consumption amount for each attribute and calculates a sum of the obtained toner consumption amounts as a toner consumption amount in forming the toner image. An image quality determination unit for determining which of the plurality of image quality with different resolutions the image quality set for the toner image is based on setting information indicating a state of image quality setting;
The calculation unit includes a number of pixel values by and demographic pixels counted by the counting unit, before conform to kidou operation speed and defined by the toner image pixel value by and compatible with the resolution of attribute The image forming apparatus according to claim 1, wherein a toner consumption amount for each pixel value and attribute is calculated based on the coefficient, and a total sum of the obtained toner consumption amounts is calculated as a toner consumption amount in forming the toner image. An image generation unit that generates the image data by applying any one of a plurality of gradation reproduction methods uniformly to the entire image or for each region in the image;
The counting unit counts the number of pixels of the image data for each pixel value, for each attribute, and for each applied gradation reproduction method,
The calculating unit is configured and the counted number of pixel values by and demographic and tone reproduction method by the pixel by counting section, before kidou operation adapted to the speed and resolution matching pixel values by said toner image And calculating toner consumption by pixel value, by attribute, and by gradation reproduction method based on a coefficient determined for each attribute and for each gradation reproduction method, and the total amount of toner consumption obtained is calculated as the toner image. The image forming apparatus according to claim 2, wherein the image forming apparatus calculates the toner consumption amount in forming the toner. A method of calculating the toner consumption amount by the mode specified in the time required to determine the operation speed switching capable images forming device of the image formation by an electrophotographic process,
When forming a toner image corresponding to the image data, the image data is classified according to the pixel value and the attribute that distinguishes the edge attribute pixel and the non-edge attribute pixel indicated by the attribute information added to the image data. Count the number of pixels,
Determine which speed level the operation speed switched by mode designation is ,
Based on the counted number of pixels for each pixel value and each attribute, and a coefficient determined for each pixel value and each attribute that matches the determined speed level , the toner consumption amount for each pixel value and each attribute is calculated. A method for calculating a toner consumption amount, comprising: calculating and calculating a total toner consumption amount as a toner consumption amount in forming the toner image. The mode specifying a computer program executed by a computer for calculating the toner consumption in the time required to determine the operation speed switching capable images forming device of the image formation by an electrophotographic process,
In response to the image forming apparatus forming a toner image corresponding to the image data, the pixel having the edge attribute and the pixel having the non-edge attribute indicated by the attribute information added to the image data for each pixel value are distinguished. A counting process for counting the number of pixels of the image data for each attribute to be performed;
Based on the number of pixels for each pixel value and attribute counted by the counting process, and a coefficient determined for each pixel value and attribute that matches the operation speed switched by mode designation, and for each pixel value and A computer program for causing the computer to execute calculation processing for calculating a toner consumption amount for each attribute and calculating a sum of the obtained toner consumption amounts as a toner consumption amount in forming the toner image.

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