JP5817268B2 - 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-described object is an image forming apparatus that forms a toner image corresponding to image data, and performs any one of a plurality of gradation reproduction methods for the entire image or for each region in the image. applied to the image and the image generation unit for generating data, edge attribute of pixels and non-edge attributes of pixels and the distinguishing demographic and the image represented by the attribute information added to the pixel value by and the image data in the For each gradation reproduction method applied by the generation unit , the current operating environment is classified in advance based on the output of a counting unit that counts the number of pixels of the image data and a sensor that detects at least one of temperature and humidity. by environmental determination unit for determining which of the plurality of environment, and the counted number of pixel values by and demographic and gradation reproduction method different pixels by the counting section, the environment judgment Based on the coefficients determined for has been adapted pixel-value-basis and by demographic and tone reproduction method in the environment determined by, calculating the specific pixel value and demographic and gradation reproduction method different toner consumption, A calculation unit that calculates the total amount of toner consumption obtained as toner consumption in the formation of the toner image , and one of a plurality of gradation reproduction methods applied by the image generation unit is an error diffusion method The calculation unit uses coefficients determined for each pixel value and each environment for edge attribute pixels to which the error diffusion method is applied, and for non-edge attribute pixels to which the error diffusion method is applied. The toner consumption amount is calculated using a coefficient determined for each pixel value but not for each environment.

  According to the present invention, the toner consumption amount is calculated by discriminating whether it corresponds to an edge and applying a coefficient determined according to the operating environment in units of pixels, so that the toner consumption amount depends on the operating environment. 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 environmental dependence of a toner adhesion characteristic. It is a figure which shows qualitatively the integrated operation amount dependence of a toner adhesion characteristic. 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 1st modification of a coefficient table. It is a figure which shows the 1st modification of a coefficient table. It is a figure which shows the 1st modification of a coefficient table. It is a figure which shows the 2nd modification of a coefficient table. It is a figure which shows the 2nd 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 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.

  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 value between adjacent pixels in the figure is a threshold value or more.

  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 that executes a control program, a RAM 82 that is a work area for executing the program, and a CSIC (Customer Specific Integrated Circuit) as a nonvolatile memory 83 that stores various data. Have. 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 operating environment (temperature and humidity) of the printer engine 10 and the integrated operation amount are taken into consideration. This is because the amount of toner adhering to the photoreceptor depends on the operating environment and also depends on the degree of wear of the members related to image formation such as the photoreceptor and developer. The CPU 81 of the engine controller 80 stores the output of the temperature / humidity sensor 52 assembled in the printer engine 10 and non-volatile memories 91, 92, 93, 94 provided in the detachable imaging units 11, 12, 13, 14 respectively. The coefficient to be applied to the calculation is fetched from the coefficient tables T1, T2, and T3 according to the accumulated operating amount DU.

  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.

  The accumulated operation amount DU stored in the imaging units 11, 12, 13, and 14 is updated in a timely manner to reflect the number of prints counted by the operation amount counter 54, the number of rotations of the photosensitive drum, and the like. Is done.

  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 photoreceptor is substantially proportional to the exposure area (that is, pixel value), but not completely proportional. In other words, if the toner consumption amount is 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. Accordingly, it is necessary to calculate the toner consumption for each pixel value by 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 environmental 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. As shown in FIG. 6A, more toner adheres in the NN environment than in the LL environment and in the HH environment compared to the NN environment over the entire exposure amount range. Here, the LL environment is a state where the temperature is less than 15 ° C. and the humidity is less than 30%, the NN environment is a state where the temperature is 15 ° C. or more and less than 26 ° C. and the humidity is 30% or more and less than 70%, and the HH environment is The temperature is 26 ° C. or higher and the humidity is 70% or higher.

  The image forming apparatus 1 has an automatic stabilization function, and adjusts, for example, the developing bias voltage (Vdc) in order to reduce the influence of the operating environment on the density of the printed image. As a result, as shown in FIG. 6B, the toner adhesion amount corresponding to the maximum exposure amount is set to a predetermined value regardless of the operating environment.

  However, 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 operating environment. Therefore, in order to calculate the toner consumption more accurately, it is necessary to reflect the operating environment during printing in the calculation.

  FIG. 7 qualitatively shows the dependence of the toner adhesion characteristics on the accumulated operation amount. As shown in the figure, the larger the exposure amount per pixel, the larger the toner adhesion amount on the photoreceptor. Then, as shown in FIG. 7A, more toner adheres when the integrated operation amount is smaller over the entire exposure amount range. Here, the accumulated operation amount is a ratio of the current accumulated number of rotations with respect to the standard life of the photoreceptor expressed by the number of rotations. For example, “small” is less than 30%, “medium” is 30% or more and less than 70%, and “many” is 70% or more.

  As shown in FIG. 7B, even if the above-mentioned automatic stabilization function is adjusted to set the toner adhesion amount corresponding to the maximum exposure amount to a predetermined value, it corresponds to the exposure amount excluding the minimum exposure amount and the maximum exposure amount. The amount of toner attached varies depending on the accumulated operating amount. Therefore, in order to calculate the toner consumption more accurately, it is necessary to reflect the accumulated operation amount during printing in the calculation.

  FIG. 8 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 determined based on the basic toner adhesion amount determined in advance according to the pixel value and edge attribute (edge pixel or non-edge pixel), the printing operation environment and the accumulated operation amount. 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. 6 and 7, 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. 9 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 every 64 pixel values from 0 to 63, three cases are classified according to the operating environment. There are three cases according to the accumulated operating amount.

  The coefficient table T2 shown in FIG. 10 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.

  A coefficient table T3 shown in FIG. 11 has correction coefficients when binarization is applied when generating raster images D4y, D4m, D4c, and D4k. In the binarization, pixel values are not distinguished, and each of the two pixel types classified into edge pixels and non-edge pixels is divided into three cases according to the operating environment, and each case is further integrated. There are three cases according to the amount of operation. 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. 12 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 output of the temperature / humidity sensor 52 to determine which of the above three environments corresponds to the current operating environment (S14), and stores it in the nonvolatile memories 91, 92, 93, 94. It is determined whether the value of the accumulated operation amount DU as the stored durability information corresponds to any of the above-mentioned three ranges (small, medium, or large) (S15). The operation in step S14 is an operation as an environment determination unit, and the operation in step S15 is an operation as an operation status determination unit.

  In accordance with the gradation reproduction method determined in steps S13 to S15, the operating environment, and the range of accumulated operating amounts, the CPU 81 sets the count values for the number of pixels for each pixel value and each edge attribute from the coefficient tables T1, T2, and T3. A corresponding correction coefficient is selected (S16). Then, the CPU 81 multiplies the count value of each pixel number, the basic toner adhesion amount per pixel corresponding thereto, and the selected correction coefficient, and adds the obtained products to obtain the toner consumption amount per image ( S17).

  FIGS. 13, 14 and 15 show coefficient tables T1b, T2b and T3b used in the first modification of the toner consumption calculation. These coefficient tables T1b, T2b, and T3b are used when calculating the toner consumption amount that is not divided according to the integrated operation amount in the calculation of the toner consumption amount. If the influence of the accumulated operation amount on the toner adhesion is slight, the case classification based on the accumulated operation amount can be omitted.

  The coefficient table T1b in FIG. 13 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. 14 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 operating environment. Thus, 384 correction coefficients are stored in each of the coefficient tables T1b and T2b. The coefficient table T3b in FIG. 15 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 operating environment, and a total of six correction coefficients are stored.

  16 and 17 show coefficient tables T1c and T3c used in the second modified example of the toner consumption calculation. The second modified example has a tendency that “when the error diffusion method is applied, the influence of the operating environment on the toner adhesion of the non-edge pixels is small and when the binarization is applied, the influence of the operating environment is small”. Suitable for the situation seen. It is possible to reduce the number of correction counts by omitting the case classification depending on the operating environment for the pixel type having a small influence, thereby reducing the data amount of the coefficient tables T1c and T3c. That is, the coefficient table T1c in FIG. 16 is a coefficient table applied to a raster image generated by the error diffusion method, and the edge attribute pixels are determined by pixel value, operation environment, and operation amount range. A correction coefficient is indicated, and for a pixel having a non-edge attribute, a correction coefficient that is determined for each pixel value and for each operation amount range but not for each operation environment is indicated. A coefficient table T3c in FIG. 17 is a coefficient table applied to a raster image generated by binarization, and is determined for each pixel value and each operation amount range for edge attribute pixels and non-edge pixels. The correction coefficient which is not defined separately is shown.

  According to the above embodiment, the toner consumption is more accurately calculated using the correction coefficient corresponding to the operating environment, and the 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 embodiment described above, the toner adhesion amount per pixel is calculated by multiplying the basic toner adhesion amount by the correction coefficient indicated by the coefficient tables T1, T2, T3, T1b, T2b, T3b, T1c, and T3c. The toner adhesion amount calculated in advance is stored as a coefficient in the coefficient tables T1, T2, T3, T1b, T2b, T3b, T1c, and T3c, and the coefficient is multiplied by the count value of the number of pixels. The total sum of products may be calculated as a toner consumption amount per image.

  The coefficient tables T1, T2, T3, T1b, T2b, T3b, T1c, and T3c have been described as commonly applied to the four colors. However, if there is a significant difference in toner adhesion characteristics among the four colors, the coefficient table Coefficient tables T1, T2, T3, T1b, T2b, T3b, T1c, and T3c may be prepared for each color. 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 operating environment categories is not limited to three as illustrated, but may be two or more. The number of integrated operation amount categories is not limited to three as illustrated, and may be two or more.

1 Image forming apparatus D4y, D4m, D4c, D4k Raster image (image data)
81 CPU (counting unit, environment determining unit, calculating unit, operating status determining unit)
52 Temperature / humidity sensor 70 Printer controller (image generator)
T1, T2, T3, T1b, T2b, T3b, T1c, T3c coefficient table

Claims (5)

An image forming apparatus that forms a toner image corresponding to image data,
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;
For each pixel value, for each attribute for distinguishing between edge attribute pixels and non-edge attribute pixels indicated by attribute information added to the image data, and for each gradation reproduction method applied by the image generation unit , the image A counter for counting the number of pixels of data;
An environment discriminating unit for discriminating which of the plurality of previously classified environments the current operating environment is based on the output of a sensor that detects at least one of temperature and humidity;
The number of the count by counting pixel values by and demographic and tone reproduction method by unit pixels, by the pixel-value-basis and the attribute adapted to the determined environment by the environment judgment unit and by the tone reproduction method Based on the determined coefficient, the toner consumption amount is calculated for each pixel value, for each attribute, and for each gradation reproduction method, and the sum of the obtained toner consumption amounts is calculated as the toner consumption amount in the formation of the toner image. A calculation unit ,
One of a plurality of gradation reproduction methods applied by the image generation unit is an error diffusion method,
The calculation unit uses a coefficient determined for each pixel value and environment for an edge attribute pixel to which the error diffusion method is applied, and for each pixel value for a non-edge attribute pixel to which the error diffusion method is applied. The toner consumption is calculated using a coefficient that is determined and not determined for each environment.
An image forming apparatus. An operating state determining unit that determines which of a plurality of predetermined operating amount ranges the accumulated operating amount recorded in the image forming apparatus is;
The calculation unit conforms to the number of pixels counted by the counting unit according to pixel value, attribute, and tone reproduction method, and the environment determined by the environment determination unit, and is determined by the operation status determination unit. based on the has been operated weight ranges stipulated pixel-value-basis and by demographic and gradation reproduction method compatible with the coefficient, out calculation the toner consumption Alternatively another and demographic and tone reproduction pixel value The image forming apparatus according to claim 1. It has a table showing coefficients defined by gradation reproduction method, pixel value, attribute, environment, and operation amount range,
The calculation unit extracts coefficients corresponding to the environment determined by the environment determination unit and the operation amount range determined by the operation status determination unit from the table, and reproduces the gradation by pixel value, attribute, and gradation. The image forming apparatus according to claim 2 , wherein the image forming apparatus is used for calculating the toner consumption amount for each method. A method for calculating a toner consumption amount in an image forming apparatus that forms a toner image corresponding to image data,
Applying any one of a plurality of gradation reproduction methods to the entire image uniformly or for each region in the image, to generate the image data,
Gradation reproduction applied to the generation of the image data for each pixel value that can be taken by the image data 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 For each method , the number of pixels of the image data is counted,
Based on the output of a sensor that detects at least one of temperature and humidity, determine whether the current operating environment is a plurality of pre-classified environments,
Based on the number of pixels counted for each pixel value, attribute, and gradation reproduction method, and the coefficient determined for each pixel value and attribute and adapted to the determined environment, and for each pixel value, attribute, and Calculating a toner consumption amount for each gradation reproduction method, and calculating a total toner consumption amount obtained as a toner consumption amount in the formation of the toner image ;
One of a plurality of gradation reproduction methods applied to the generation of the image data is an error diffusion method,
In calculating toner consumption by pixel value, attribute, and tone reproduction method, error diffusion is applied to pixels with edge attributes to which the error diffusion method is applied, using coefficients determined by pixel value and environment. A non-edge attributed pixel to which the law is applied uses a coefficient that is determined for each pixel value but not for each environment, and a method for calculating a toner consumption amount. A computer program executed by a computer for calculating toner consumption in an image forming apparatus that forms a toner image corresponding to image data ,
An image generation processing for generating the image data by applying one to each area of uniform or the image for the entire image of a plurality of tone reproduction methods,
For each pixel value, for each attribute that distinguishes between edge attribute pixels and non-edge attribute pixels indicated by the attribute information added to the image data, and for each gradation reproduction method applied to the generation of the image data , A counting process for counting the number of pixels of the image data;
An environment determination process for determining which of a plurality of pre-classified environments the current operating environment is based on the output of a sensor that detects at least one of temperature and humidity;
The number of the counting process counts pixel values by and demographic and gradation reproduction method different pixels by, by the environment determination processing determined environment to fit the pixel-value-basis and attribute by and by the tone reproduction method Based on the determined coefficient, the toner consumption amount is calculated for each pixel value, for each attribute, and for each gradation reproduction method, and the sum of the obtained toner consumption amounts is calculated as the toner consumption amount in the formation of the toner image. Calculation processing is executed by the computer ,
One of a plurality of gradation reproduction methods applied in the image generation process is an error diffusion method,
In the calculation process, for edge attribute pixels to which the error diffusion method is applied, coefficients determined for each pixel value and for each environment are used, and for non-edge attribute pixels to which the error diffusion method is applied, for each pixel value. The toner consumption is calculated using a coefficient that is determined and not determined for each environment.
A computer program characterized by that.

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