JP2024175516A - Image forming device - Google Patents

Abstract

To solve the problem in which: toner consumption cannot be determined by a plurality of methods.SOLUTION: An image forming apparatus 102 has: a halftone unit 504 that executes halftone processing on image data; a density correction unit 503 that converts the image data on the basis of a conversion condition; a printer engine 104 that forms an image by using toner on the basis of image data obtained through the conversion; a toner amount calculation unit 510 that determines toner consumption on the basis of the image data before being converted by the density correction unit 503; and a toner amount calculation unit 505 that determines toner consumption on the basis of the image data after being converted by the density correction unit 503.SELECTED DRAWING: Figure 12

Description

The present invention relates to a remaining amount determination process that determines the remaining amount of toner in an image forming device.

Some electrophotographic copiers and printers calculate the amount of toner consumed each time an image is formed, and display the remaining toner amount on a panel based on the calculation results. One method for detecting the remaining toner amount is to use a sensor, but this method is subject to mechanical constraints due to miniaturization and space saving, and problems arise such as increased costs due to the addition of parts and design changes. For this reason, several methods have been proposed for estimating the amount of toner consumed from image data.

In Patent Document 1, the density value of each pixel of multi-value input image data before halftone correction processing is calculated, and the density value of each pixel is converted into the toner consumption amount, and the count value is added up for each page, thereby calculating the toner consumption amount for each page. Halftone correction processing is a process that corrects the input signal value so that the relationship between the input signal value and the density of the gradation part becomes an ideal constant state. Therefore, in models that perform halftone correction processing, it is known that the toner consumption amount of the gradation part can be calculated with high accuracy by calculating the toner consumption amount using the multi-value image data before halftone correction processing.

Patent Document 2 proposes the following method to take into account the phenomenon (edge effect) in which print dots placed on the edge of an image consume more toner than parts where print dots are placed comprehensively (solid parts). This method involves preparing a weighting factor according to the number of consecutive print pixels in advance, multiplying each pixel by the corresponding weighting factor to find the toner consumption per pixel, and accumulating this for all pixels in the image to calculate the toner consumption for one page of an image. It is known that this method can be used to accurately calculate the toner consumption for text parts, which are strongly affected by the edge effect.

JP 2007-114593 A JP 2009-98185 A

However, the toner consumption calculation method of Patent Document 1 can accurately calculate the toner consumption in gradation areas, but has the problem that it does not calculate the toner consumption in text areas, which are strongly affected by edge effects, with high accuracy. The toner consumption calculation method of Patent Document 2 can accurately calculate the toner consumption in text areas, but has the problem that it does not calculate the toner consumption in gradation areas, where pixel on/off patterns are repeated at high density and many complex dot patterns exist.

Therefore, if one of the toner consumption calculation methods is used, and many image patterns are included that have low calculation accuracy using the selected toner consumption calculation method, a large error will occur in the calculation of toner consumption. In other words, the problem with conventional image forming devices is that toner consumption can only be determined using one predetermined method.

The present invention aims to provide an image forming device that determines toner consumption using multiple methods.

To solve the above problem, the image forming device of the present invention is characterized by having a halftone processing means for performing halftone processing on image data, a conversion means for converting the image data based on conversion conditions corresponding to the type of halftone processing, an image forming means for forming an image using toner based on the image data converted by the conversion means, a first determination means for determining the amount of toner to be consumed by the image forming means based on the image data before being converted by the conversion means, and a second determination means for determining the amount of toner to be consumed by the image forming means based on the image data after being converted by the conversion means.

According to the present invention, toner consumption can be determined in a number of ways.

1 is a diagram showing an overall configuration of an image forming apparatus; Cross-sectional view of an image forming apparatus Printer engine configuration diagram Video controller configuration diagram Data processing unit configuration diagram Configuration diagram of density correction processing unit Configuration diagram of toner amount calculation unit 1 Graph showing the relationship between pixel value and toner consumption Pixel Value Correction Table Configuration diagram of toner amount calculation unit 2 Example of counter value correction based on line width 1 is a flowchart of a process for calculating a remaining amount of toner according to the first embodiment; FIG. 1 shows the effects of the first and second embodiments. 11 is a flowchart of a process for calculating a remaining amount of toner according to a second embodiment of the present invention; Example table of identification values for printing applications and toner calculation methods

Below, a preferred embodiment of the present invention will be described in detail by way of example with reference to the drawings. However, the relative positions and numerical values of the components described in this embodiment are not intended to limit the scope of the present invention to those alone unless otherwise specified.

Example 1
(Overall configuration of image forming apparatus)
The configuration of the image forming apparatus 102 will be described with reference to FIG. 1. In this embodiment, a color image forming apparatus that forms an image using four color materials (coloring materials) of yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and K) will be described. The image forming apparatus 102 has a video controller 103 that performs various controls and data processing, and a printer engine 104 that forms a visualized image on a transfer material. The transfer material is also called a recording material, a recording medium, a paper, a sheet, or a transfer paper. A host computer 101 and the like are connected to the image forming apparatus 102 via a network, a parallel interface, a serial interface, or the like. The host computer 101 issues a print execution request to the image forming apparatus 102 based on print conditions (e.g., paper size, number of copies, print orientation, print purpose, etc.) set by a user on a printer driver. The video controller 103 rasterizes print data sent from the host computer 101 together with an instruction to execute printing into image data, performs data processing (described later), and sends the data to the printer engine 104.

(Printer engine control)
2 and 3, the operation of an electrophotographic printer engine 104 that forms a multi-color image using Y, M, C, and K toners will be described. When describing matters common to the four colors, the letters YMCK will be omitted from the reference symbols. FIG. 2 shows an example of an electrophotographic image forming apparatus 102. The image forming apparatus 102 is a tandem-type color image forming apparatus that employs an intermediate transfer body 27. FIG. 3 is a block diagram showing a control unit of the printer engine 104. The printer engine 104 has an engine control unit 301 and an engine mechanism unit 302. The engine mechanism unit 302 operates according to various instructions from the engine control unit 301.

The laser/scanner system 308 of the engine mechanism section 302 has the scanner section 24 shown in FIG. 2. The scanner section 24 includes a laser light emitting element, a laser driver circuit, a scanner motor, a rotating polygon mirror, a scanner driver, etc. The scanner section 24 turns on the laser in accordance with a laser drive signal indicating the laser exposure time sent from the video controller 103, and exposes and scans the photosensitive drum 22 by reflecting the laser light by the rotating polygon mirror. The exposure light selectively exposes the surface of the photosensitive drum 22, forming an electrostatic latent image.

The image forming system 309 is the central part of the printer engine 104, and develops the latent images formed on the photosensitive drums 22Y, 22M, 22C, and 22K to form toner images, which are then transferred to a transfer material and fixed. As shown in FIG. 2, the image forming system 309 has four image forming units. Each image forming unit has a photosensitive drum 22, a charger 23, and a developer 26. The image forming system 309 further has an intermediate transfer body 27, a transfer roller 28, and a fixing unit 30, as well as a high-voltage power supply circuit that generates various biases (high voltages) required for image formation. The chargers 23Y, 23M, 23C, and 23K have charging rollers 23YS, 23MS, 23CS, and 23KS that uniformly charge the surfaces of the photosensitive drums 22Y, 22M, 22C, and 22K. The developing units 26Y, 26M, 26C, and 26K, which are developing means, each have a developing sleeve 26YS, 26MS, 26CS, and 26KS for attaching a toner image to the latent image.

The charger 23, the developer 26 and the photosensitive drum 22 are detachably attached to the main body of the image forming apparatus 102 as a process cartridge. The intermediate transfer body 27 is driven by a drive roller 25, and the toner image is primarily transferred from the photosensitive drums 22Y, 22M, 22C and 22K. The transfer roller 28 comes into contact with the intermediate transfer body 27, and the transfer material 11 is sandwiched and transported, and the toner image on the intermediate transfer body 27 is secondarily transferred to the transfer material 11. The transfer roller 28 abuts against the transfer material 11 while the toner image is being transferred onto the transfer material 11, and moves away from the intermediate transfer body 27 when the transfer is completed. The fixing unit 30 melts and fixes the toner image while transporting the transfer material 11.

The fixing unit 30 includes a fixing roller 31 that heats the transfer material 11, and a pressure roller 32 that presses the transfer material 11 against the fixing roller 31. The fixing roller 31 and the pressure roller 32 are hollow, and heaters 33 and 34 are installed inside, respectively. The cleaning unit 29 cleans toner remaining on the intermediate transfer body 27. Each of the four process cartridges has a non-volatile memory device. The CPU 303 and ASIC 304 of the engine control unit 301 read and write various information (total number of images formed and operating time) from and to the memory device.

The paper feed/transport system 310 is responsible for feeding and transporting the transfer material 11, and is composed of various transport system motors, the paper feed section 21 (paper feed cassette 21a and paper feed tray 21b), paper feed rollers, and various transport rollers including a paper discharge roller. The paper feed/transport system 310 feeds and transports the transfer material 11 from the paper feed cassette 21a or paper feed tray 21b in accordance with the operation of the image creation system 309.

The sensor system 311 is a group of sensors that collect information required for the CPU 303 and ASIC 304 to control the laser/scanner system 308, the imaging system 309, and the paper feed/transport system 310. This group of sensors includes a temperature sensor for the fixing unit 30, a density sensor 40 that detects the density of the toner image formed on the photoconductor drum 22, the intermediate transfer body 27, or the transfer material 11, a sensor that detects color shift, a paper size sensor, a paper leading edge detection sensor, a paper transport detection sensor, and the like. The CPU 303 acquires the information detected by the sensor system 311 and reflects it in the control of the print sequence.

The CPU 303 of the engine control unit 301 uses the RAM 305 as a main memory and a work area, and controls the engine mechanism unit 302 according to various control programs stored in the non-volatile storage unit 306. The system bus 312 has an address bus and a data bus. The components of the engine control unit 301 and the engine mechanism unit 302 are connected to the system bus 312 and can access each other.

When the CPU 303 receives a print execution command from the video controller 103 via the engine interface unit 307, it first drives the image creation system 309 and charges the surface of the photoconductor drum 22 with the charger 23. The CPU 303 generates and outputs a laser drive signal to drive the laser/scanner system 308, and forms an electrostatic latent image on the photoconductor drum 22 with the scanner unit 24.

Next, CPU 303 drives image-forming system 309, causing developer 26 to develop the electrostatic latent image to form a monochrome toner image. This monochrome toner image is primarily transferred onto intermediate transfer body 27 so that the images are superimposed on the intermediate transfer body 27, forming a full-color toner image on the intermediate transfer body 27. CPU 303 controls paper feed/transport system 310, causes the paper feed roller to feed transfer material 11 from paper feed unit 21, and transfers the toner image onto transfer material 11. CPU 303 then controls fixing unit 30 to fix the toner image on transfer material 11.

The ASIC 304 controls the motors and high-voltage power supplies such as the development bias when executing various print sequences in accordance with instructions from the CPU 303. Note that the CPU 303 may be configured to realize some or all of the functions of the ASIC 304.

(Video Controller Configuration)
An example of the configuration of the video controller 103 will be described with reference to Fig. 4. The CPU 401 is a CPU that controls the entire video controller 103. The non-volatile storage unit 402 is a storage means that stores various control codes executed by the CPU 401 and data used for control. The storage unit 402 is, for example, a ROM, an EEPROM, or a hard disk. The storage unit 402 stores a tone correction table as a conversion condition used to convert image data. The RAM 403 is a temporary storage memory that functions as the main memory, work area, etc. of the CPU 401.

The host interface unit 404 is an interface that receives print data and control data from the host computer 101. The print data received by the host interface unit 404 is stored in the RAM 403. Here, the print data may be bitmap data after halftone processing has been performed in the host computer 101, or it may be PDL (page description language) data. PDL data is data described in a page description language. The print data includes attribute data for characters, graphics, and photographs.

The DMA control unit 407 transfers data in the RAM 403 to the engine interface unit 409 and the data processing unit 406 in response to instructions from the CPU 401. The data processing unit 406 performs various data processing (e.g., estimating toner consumption) on the image data in the RAM 403 in response to instructions from the CPU 401. The detailed operation of the data processing unit 406 will be described later.

The operation/display unit 408 accepts various settings and instructions input from the user, and displays various information about the image forming device 102. The engine interface unit 409 is an input/output unit for signals to the printer engine 104. For example, the engine interface unit 409 sends a laser drive signal output from the data processing unit 406 to the printer engine 104.

The toner amount management unit 405 updates the remaining amount of toner in the process cartridge based on the amount of toner consumed per page notified by the data processing unit 406, and displays it on the operation/display unit 408. The toner amount management unit 405 may notify the host computer 101 of the remaining amount of toner via the host interface unit 404.

The density correction processing unit 411 performs density correction processing according to instructions from the CPU 401 or instructions from the printer engine 104 via the engine interface unit 409. The density correction processing unit 411 generates a gradation correction table used during density correction by the density correction unit 503 described below. The gradation correction table generated by the density correction processing unit 411 is stored in the memory unit 402. The detailed operation of the density correction processing unit 411 will be described later.

The system bus 410 has an address bus and a data bus. Each of the above-mentioned components is connected to the system bus 410 and can access each other. The functions of the data processing unit 406 may be realized as an ASIC (application specific integrated circuit) or dedicated hardware, or some or all of the functions may be realized by the CPU 401. Alternatively, some or all of the functions of the video controller 103 may be realized by the host computer 101.

(Configuration of Data Processing Unit)
5 is a block diagram for explaining the processing contents of the data processing unit 406. The RIP unit 501 analyzes the contents of image data described in PDL stored in the RAM 403 to generate intermediate language data, and further rasterizes the intermediate language data to generate raster image data. RIP is an abbreviation for raster image processor. The raster image data is written to the RAM 403 as RGB image data.

The color conversion unit 502 performs color matching processing to convert the RGB image data into device RGB signals that match the color reproduction range of the image forming device 102. Furthermore, the color conversion unit 502 performs color separation processing to convert the device RGB signals into YMCK signals, which are the toner color material colors of the image forming device 102. In this way, the color conversion unit 502 sequentially converts the RGB image data output by the RIP unit 501 into YMCK image data and writes it to the RAM 403.

The density correction unit 503 converts each tone value of the YMCK signal (image data) output by the color conversion unit 502 based on the tone correction table stored in the storage unit 402 (FIG. 4). This is to make the relationship between each tone value of the YMCK signal (image data) and the density of the image formed on the transfer material 11 by the printer engine 104 a desired relationship. Here, the density correction unit 503 selects a conversion condition (tone correction table) from a plurality of conversion conditions (tone correction tables) based on the printing purpose. This is because the conversion condition (tone correction table) is generated corresponding to the type of halftone processing (halftone processing) used by the halftone unit 504 described later. The density correction unit 503 converts the image data based on the conversion condition (tone correction table) corresponding to the type of halftone processing (halftone processing) applied to the image data by the halftone unit 504 described later. The printing purpose can also be said to be user instruction information regarding the tone correction table corresponding to the type of halftone processing (halftone processing).

The halftone unit 504 performs halftone processing on the image data (8 bits) of each color corrected by the density correction unit 503. Halftone processing is also called dither processing. As a result, the image data of each color is converted into 1-bit image data that can be reproduced by the printer engine 104, and stored in the image memory in the RAM 403. Here, the halftone unit 504 switches the type of halftone processing based on the printing purpose. For example, if the printing purpose is a document, the halftone unit 504 performs halftone processing on the image data using a 200-line dither (high-line dither). For example, if the printing purpose is a photograph, the halftone unit 504 performs halftone processing on the image data using a 140-line dither (low-line dither). The printing purpose can also be said to be user instruction information regarding the type of halftone processing.

The toner amount calculation unit 2 (505) calculates the amount of toner consumed per page (toner consumption amount) for each color component based on image data (halftone processed image data) that has been halftone processed by the halftone unit 504. The toner amount calculation unit 2 (505) determines the toner consumption amount from the halftone processed image data stored in the image memory of the RAM 403. Note that the toner amount calculation unit 2 (505) of this embodiment is not limited to a configuration that determines the toner consumption amount based on halftone processed image data that has been halftone processed by the halftone unit 504. For example, the toner amount calculation unit 2 (505) may be configured to determine the toner consumption amount based on image data converted by the density correction unit 503 before being input to the halftone unit 504. For example, the toner amount calculation unit 2 (505) may be configured to determine the toner consumption amount based on a laser drive signal that has been PWM processed by the PWM unit 506 described later.

The PWM unit 506 converts the halftone processed image data in the image memory into a laser drive signal (laser exposure time) using PWM (Pulse Width Modulation) processing.

The toner amount calculation unit 1 (510) calculates the amount of toner consumed per page (toner consumption amount) for each color component based on the image data (color conversion processed image data) before being converted by the density correction unit 503. The toner amount calculation unit 1 (510) determines the toner consumption amount from the color conversion processed image data stored in the image memory of the RAM 403. Here, in order to determine the toner consumption amount according to the density of the original (original image), the toner amount calculation unit 1 (510) calculates the toner consumption amount based on the image data before the conversion process by the density correction unit 503, the halftone unit 504, and the PWM unit 506 is performed. However, the toner consumption amount when printing characters or figures deviates from the toner consumption amount predicted by the toner amount calculation unit 1 (510) due to the influence of the edge effect. Therefore, the image forming apparatus 102 has a toner amount calculation unit 2 (505) that determines the amount of toner consumption based on the image data after conversion processing by the density correction unit 503, the halftone unit 504, and the PWM unit 506, in addition to the toner amount calculation unit 1 (510).

The toner consumption calculated by toner amount calculation unit 1 (510) and the toner consumption calculated by toner amount calculation unit 2 (505) are input to toner amount management unit 405. The detailed operations of toner amount calculation unit 1 (510), toner amount calculation unit 2 (505), and toner amount management unit 405 will be described later.

(Configuration of Density Correction Processing Unit)
6 is a block diagram for explaining the processing contents of the density correction processing unit 411. In the density correction processing, in order to control the gradation characteristics (also called gamma characteristics) of the printer engine 104 to ideal gradation characteristics for each color of YMCK, a gradation correction table is generated based on the measurement results of the gradation patch image. The gradation patch image is an image that the printer engine 104 forms on the intermediate transfer body 27 in order to detect the gradation characteristics of the printer engine 104. The gradation patch image has a plurality of images with different gradations.

The gradation characteristic detection unit 601 determines the gradation characteristics of the printer engine 104 based on the measurement results of the gradation patch image measured by the density sensor 40. The correction table calculation unit 602 generates a gradation correction table that converts the signal values of the image data so that the gradation characteristics determined by the gradation characteristic detection unit 601 become ideal gradation characteristics. The gradation correction table is then stored in the memory unit 402. The image forming device 102 converts the signal values of the YMCK signals of the image data based on the gradation correction table in order to maintain the desired relationship between each gradation value of the YMCK signal (image data) and the density output on the transfer material 11.

(Video controller operation)
The following describes the overall flow from receiving a print command from the host computer 101 to transmitting data to the printer engine 104. When a print command is received from the host computer 101 via the host interface unit 404, the CPU 401 receives the print data via the host interface unit 404 and stores it in the RAM 403.

Next, the CPU 401 controls the RIP unit 501 of the data processing unit 406 to rasterize the print data in the RAM 403. The print data that has been rasterized is image data. The CPU 401 further controls the color conversion unit 502 to perform color conversion processing on the image data, controls the density correction unit 503 to perform density correction processing on the image data (color conversion processed image data), and controls the halftone unit 504 to perform halftone processing on the image data. Furthermore, the CPU 401 controls the PWM unit 506 to generate a laser drive signal from the image data (halftone processed image data), and transmits the laser drive signal to the printer engine 104 via the engine interface unit 409. At this time, the toner amount calculation unit 1 (510) and the toner amount calculation unit 2 (505) calculate the toner consumption amount for each color component according to the instruction of the CPU 401, and notify the toner amount management unit 405 of the calculation result. The color components are yellow, magenta, cyan, and black.

(Operation of Toner Amount Calculation Unit 1)
The detailed operation of toner amount calculation unit 1 (510) will be described. Fig. 7 shows an example of the configuration of toner amount calculation unit 1 (510). Here, black (K) will be used as an example. Note that the process of calculating the toner consumption amounts of yellow (Y), magenta (M), and cyan (C) is the same as the process of calculating the toner consumption amount of black (K), so the description will be omitted below.

The toner amount calculation unit 1 (510) calculates the amount of black toner consumed based on the pixel values of the black color conversion processed image data stored in the image memory of the RAM 403. The toner amount calculation unit 1 (510) includes an image data correction unit 701, an accumulation unit 702, and a toner consumption calculation unit 703.

As shown in graph L4 of FIG. 8, the toner consumption is not proportional to the pixel value indicated by the pixel data output from the color conversion unit 502, but is nonlinear as shown in graph L5. In this embodiment, the toner consumption required for a certain pixel value is used as a reference, and a correction value weighted by a predetermined coefficient is determined in advance to eliminate the difference between the toner consumption required for each pixel value and the reference toner consumption.

Figure 9 shows an example of a weighting coefficient table that indicates the correspondence between each pixel value of the color conversion processed image data and the weighted correction value. As shown in Figure 9, the weighting coefficient table associates each pixel value indicated by the color conversion processed image data with the correction value that corresponds to this pixel value.

The image data correction unit 701 corrects each pixel value of the color conversion processed image data based on the weighting coefficient table. That is, if the pixel value of the color conversion processed image data is, for example, 31, the image data correction unit 701 converts the pixel value 31 to a weighting value 23 based on the weighting coefficient table.

The accumulator 702 accumulates the weighting value 23 output for each pixel from the image data correction unit 701. The toner consumption calculation unit 703 calculates the amount of toner consumed from the accumulated value calculated by the accumulator 702, and notifies the toner amount management unit 405 of the calculation result.

(Operation of Toner Amount Calculation Unit 2)
The detailed operation of toner amount calculation unit 2 (505) will be described. Fig. 10 shows an example of the configuration of toner amount calculation unit 1 (510). Here, black (K) will be described as an example. Note that the process of calculating the toner consumption amounts of yellow (Y), magenta (M), and cyan (C) is the same as the process of calculating the toner consumption amount of black (K), so the description will be omitted below.

The toner amount calculation unit 2 (505) calculates the amount of black toner consumed based on the line width and number of print pixels contained in the black halftone processed image data stored in the image memory of the RAM 403. The toner amount calculation unit 2 (505) includes a pattern detection unit 1001, a dot counting unit 1002, an arithmetic unit 1003, and a toner consumption calculation unit 1004.

The pattern detection unit 1001 analyzes the binary data of the halftone processed image data and detects areas of different line widths (number of consecutive print dots). Specifically, it detects multiple pixel patterns in which the number of consecutive print dots is changed in the range of 1 to 8 from the dot arrangement of the target image (an image based on the halftone processed image data).

The dot counting unit 1002 counts how many pixel patterns with consecutive print dots of 1 to 8 are there. The number of pixels that correspond to a pixel pattern with a line width of 1 pixel is counted as Count 1. The number of pixels that correspond to a pixel pattern with a line width of 2 pixels is counted as Count 2. Counting continues in the same manner, with the number of pixels that correspond to a pixel pattern with a line width of 8 pixels being counted as Count 8. The number of pixels that correspond to a pixel pattern with a line width of 9 pixels or more being counted as Count*_*.

In this embodiment, the pattern detection unit 1001 detects the corresponding area according to a predetermined line width based on the scanning direction of the laser light in the scanner unit 24, and the dot counting unit 1002 counts the number of pixels contained in the area.

The calculation unit 1003 multiplies the number of print pixels counted for each consecutive number of print dots by a correction coefficient corresponding to that category to obtain an integrated value. The correction coefficient is a numerical value that can be determined in advance based on actual measurements. For example, it is preferable to set the amount of toner consumed by one pixel of a solid image with no edge portions to 1, measure the amount of toner consumed per pixel for each pixel pattern with different line widths, and obtain the rate of change as the correction coefficient. Figure 11 shows an example of the relationship between the number of consecutive print dots and the correction coefficient.

The toner consumption calculation unit 1004 calculates the toner consumption amount using the integrated value obtained by the calculation unit 1003 and the toner consumption amount per unit pixel, and notifies the toner amount management unit 405 of the calculation result.

(Operation of Toner Amount Management Unit)
The detailed operation of toner amount management unit 405 will be described. Toner amount management unit 405 selects whether to use the toner consumption amount determined by toner amount calculation unit 1 or toner amount calculation unit 2 as the toner consumption amount for each color component. Then, toner amount management unit 405 subtracts the toner consumption amount from the total amount of toner in the process cartridge to update the remaining toner amount in the process cartridge. Operation/display unit 408 displays the remaining toner amount updated by toner amount management unit 405.

Text-based prints (documents) are imaged using black toner, while graphic-based prints are imaged using color (yellow, magenta, cyan) toners. Therefore, the toner consumption of text parts imaged using black toner is calculated using toner amount calculation unit 2. On the other hand, the toner consumption of gradation parts imaged using color (yellow, magenta, cyan) toners is calculated using toner amount calculation unit 1.

The processing flow of the toner amount management unit 405 will be explained using the flowchart in Figure 12 (S1201 to S1207).

The toner amount management unit 405 calculates the amount of toner remaining in the process cartridge each time the printer engine 104 outputs one page of image. This process proceeds in the order of yellow (Y), magenta (M), cyan (C), and black (K).

The toner amount management unit 405 determines that the color for which the remaining toner amount is to be calculated is black (K) (S1201). If the image data is black (K) in step S1201 (YES), the toner amount management unit 405 reads out the toner consumption amount determined by the toner amount calculation unit 2 (505), which has high accuracy in calculating the toner consumption amount for characters and lines (S1202).

On the other hand, if the image data is not black (K) in step S1201 (NO), the toner amount management unit 405 reads out the toner consumption amount determined by the toner amount calculation unit 1, which has high accuracy in calculating the toner consumption amount for graphics and photographs (S1203).

After the toner consumption amount is read in step S1202 or step S1203, the toner amount management unit 405 subtracts the toner consumption amount from the total amount of toner in the toner cartridge and updates (stores) the remaining toner amount (S1204). Then, the toner amount management unit 405 causes the operation/display unit 408 to display the updated remaining toner amount (S1205).

The toner amount management unit 405 determines whether the updating of the remaining toner amounts of all colors has been completed (S1206). If the updating of the remaining toner amounts of all colors has been completed in step S1206 (YES), the toner amount management unit 405 ends the process.

On the other hand, if updating of the remaining toner amounts of all colors is not complete in step S1206 (NO), the toner amount management unit 405 returns the process to step S1201 and executes the process of updating the remaining toner amounts of colors for which the remaining toner amounts have not been updated. As described above, the toner amount management unit 405 proceeds in the order of yellow (Y), magenta (M), cyan (C), and black (K). For example, when updating of the remaining toner amount of magenta (M) is finished, the toner amount management unit 405 moves the process from step S1207 to step S1201, and executes steps S1202 to S1205 to update the remaining toner amount of the next color, cyan (C).

(Explanation of effects)
Here, the effects of the invention will be described with reference to Figs. 13a, 13b and 13c.

First, we will explain how to read the plots common to Figures 13a to 13c. The horizontal axis indicates the print rate [%] within a page. The vertical axis indicates the ratio [%] of the actual toner consumption [mg/cnt] per count when the ideal toner consumption [mg/cnt] per count is used as the standard. The ideal toner consumption per count here is a typical office document. Each plot is the result of changing the type of image and the print rate within the page. Specifically, the ■ plot is an image with 100% density over the entire page (hereinafter referred to as solid), the ▲ plot is graphics or photos, the ◆ plot is text or lines, and the ● plot is a typical office document (an image with a mixture of graphics and text). The graphic image is intended for use mainly in printing POP images such as posters, and the text and lines are intended for use in printing text and drawings. The closer these plots are to 100% in Figure 13, the more accurately the toner consumption can be calculated regardless of the user's use.

Next, we will explain the accuracy of the toner consumption in each figure.

Figure 13a shows the toner amount results when calculated by toner amount calculation unit 1. The values for "solid images (■)" and "graphics and photographs (▲)" are close to 100%, which is close to the ideal toner consumption per count (●). However, it can be seen that "characters and lines (◆)" are 120-140%, which is outside the ideal toner consumption per count. In other words, this shows that when calculated by toner amount calculation unit 1, the accuracy of the toner consumption for characters and lines is not high.

Next, Figure 13b shows the toner consumption results when calculated by toner amount calculation unit 2. "Characters and lines (◆)" and "solid images (■)" have values close to the ideal toner consumption per count (●). However, "graphics and photographs (▲)" are at 120-140%. This shows that when calculated by toner amount calculation unit 2, the accuracy of toner consumption for graphics and photographs is not high.

Finally, Figure 13c shows the toner consumption results when calculated using the toner amount calculation method of the present invention. As mentioned above, characters and lines are generally formed using "K" image data, so by using the toner consumption calculated using toner consumption amount 2 for "K" image data, it can be seen that "characters and lines (◆)" will have a value close to 100%. In other words, it can be said that the toner consumption for characters and lines can be calculated with high accuracy. On the other hand, graphics and photographs are formed using "YMC" image data, so by using the toner consumption calculated using toner consumption amount 1 for "YMC" image data, it can be seen that "graphics and photographs (▲)" will have a value close to 100%. In other words, it can be said that the toner consumption for graphics and photographs can be calculated with high accuracy.

Therefore, by switching the counting method used to calculate toner consumption for each color of the YMCK image being formed, it is possible to accurately calculate toner consumption regardless of the user's printing purpose (for example, general office documents, posters or POP images, text or drawings).

In addition, in this embodiment, toner amount calculation unit 1 (510) and toner amount calculation unit 2 (505) are described as being arranged in video controller 103, but they may be arranged in printer engine 104. In addition, in this embodiment, a YMCK image is described, but an image of two or more colors including K does not have to be a YMCK image (for example, red, green, blue, white, colorless, gray, etc.).

Example 2
Another embodiment of the present invention will be described. In this embodiment, a means will be described for selecting a calculation method for toner consumption for each color of a YMCK image based on the "printing purpose" included in the printing conditions set by the user on the printer driver when the toner amount management unit calculates the toner consumption. This makes it possible to calculate the toner consumption appropriately according to the user's printing purpose.

The basic operation of the image forming device 102 in this embodiment is the same as in embodiment 1, so a description of the common parts will be omitted and only the differences will be described.

(Operation of Toner Amount Management Unit)
A detailed operation of the toner amount management unit 405 will be described. The toner amount management unit 405 selects whether to use the toner consumption amount notified from the toner amount calculation unit 1 or the toner amount calculation unit 2 for each color component based on the print application identification value (FIG. 15) stored in the RAM 403 and transmitted from the host computer 101. The toner amount management unit 405 updates the remaining toner amount in the process cartridge based on the toner consumption amount for each page and displays it on the operation/display unit 408.

From here, the processing flow of the toner amount management unit 405 will be explained using the flowchart in Figure 14 (S1401 to S1408) and Figure 15.

The toner amount management unit 405 starts calculating the remaining amount of toner in the process cartridge each time the printer engine 104 outputs an image. This process proceeds in the order of Y, M, C, and K.

The toner amount management unit 405 acquires the print purpose identification value stored in the RAM 403 (S1401). A specific example is shown in FIG. 15.

The toner amount management unit 405 determines the toner consumption amount value from the printing purpose identification value acquired in step S1401 (S1402). Specifically, as shown in FIG. 15, the toner amount management unit 405 selects the toner consumption amount notified from the toner amount calculation unit 1 or the toner consumption amount notified from the toner amount calculation unit 2 according to the toner amount calculation method defined in the printing purpose identification value and color table.

The toner amount management unit 405 updates (stores) the remaining toner amount (S1403). The remaining toner amount is calculated by subtracting the amount of toner consumption determined in step S1403 from the previous remaining toner amount. The calculated remaining toner amount is updated (stored).

The toner amount management unit 405 notifies the operation/display unit 408 of the updated remaining toner amount (S1404).

The toner amount management unit 405 determines whether the toner remaining amount has been updated for all colors (S1405). If the toner remaining amount has been updated for all colors (YES), the toner management unit 405 ends the process. If not (NO), the toner management unit 405 returns to S1402 and updates the toner remaining amount for colors that have not been updated. As described above, this process flow proceeds in the order of Y, M, C, and K, so for example, when the toner remaining amount for "M" has been updated, the process determines "NO" in S1407 and proceeds with the processes of S1402 to S1404 for the next color, "C."

(Explanation of effects)
The effect of the invention in the second embodiment will be described with reference to Fig. 13. Here, the description will be continued by taking the image data of "K" as an example.

In the first embodiment, the toner consumption amount of the "K" image data is mainly used for printing text, so the toner consumption amount calculated by the toner amount calculation unit 2 is used. However, when used for printing graphics or photographs, the calculation method of the toner amount calculation unit 2 results in a lower accuracy of the toner consumption amount (Figure 13b).

On the other hand, as in the second embodiment, the printing purpose set by the user on the printer driver is known, so that the optimum calculation method can be selected based on that information, and the toner consumption amount can be calculated with high accuracy. For example, if the printing purpose is graphics or photographs (identification value is "02"), "K" uses the toner consumption amount calculated by toner amount calculation unit 2 (Figure 13a), so the toner consumption amount is highly accurate.

Therefore, by switching the counting method used to calculate toner consumption depending on the user's print application setting and the color of the YMCK image to be formed, it is possible to accurately calculate the toner consumption that suits the user's print application.

102 Image forming apparatus 104 Printer engine 503 Density correction unit 504 Halftone unit 505 Toner amount calculation unit 2
510 Toner amount calculation unit 1

Claims (3)

A halftone processing means for performing halftone processing on image data;
a conversion means for converting the image data based on a conversion condition corresponding to the type of halftone processing;
an image forming unit that forms an image using toner based on the image data converted by the conversion unit;
a first determination unit that determines an amount of toner to be consumed by the image forming unit based on image data before being converted by the conversion unit;
and a second determination unit that determines an amount of toner to be consumed by the image forming unit based on the image data converted by the conversion unit. the image forming means includes a black image forming section for forming a black image and a color image forming section for forming a color image,
the first determining unit determines an amount of toner consumed by the color image forming unit,
2. The image forming apparatus according to claim 1, wherein the second determining unit determines an amount of toner consumed by the black image forming unit. The image processing method further includes: acquiring information regarding a type of the halftoning process to be performed on the image data;
when the halftone processing means performs a first type of halftone processing on the image data based on the information, the first determination means determines an amount of toner to be consumed by the image forming means;
2. The image forming apparatus according to claim 1, wherein when the halftone processing means performs a second type of halftone processing having a higher number of lines than the first type of halftone processing on the image data based on the information, the second determination means determines the amount of toner to be consumed by the image forming means.

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