JP6394993B2 - Image forming apparatus and toner consumption calculation method - Google Patents

Description

  The present invention relates to an image forming apparatus and a toner consumption calculation method.

  In an image forming apparatus that employs a predetermined developing method such as a touch-down developing method, for example, as shown in FIG. 6, the toner density at the rear end portion of the electrostatic latent image on the photosensitive drum becomes high. As a result, rear end accumulation occurs (see, for example, Patent Document 1). Specifically, when the developing roller rotates at a higher speed than that of the photosensitive drum, excessive toner is supplied from the image roller to the rear end of the solid image portion, thereby causing a rear end accumulation.

JP 2012-163842 A

  In order to reduce such rear end accumulation, halftone processing may be performed on the solid portion. As shown in FIG. 7, by performing the halftone process, a small rear end pool is generated for each halftone dot, and the rear end pool becomes inconspicuous.

  Therefore, in the density calibration, the solid maximum density is adjusted to a density higher than the target density, and then the halftone process is performed to reduce the solid maximum density to the target density. Since the maximum density that can be developed changes depending on the development process characteristics over time, the intensity of the halftone process is changed according to the maximum density that can be developed. That is, when the toner density is lowered due to a change over time, the strength of the halftone process is lowered, and when the toner density is further lowered and the developable maximum density is equal to or lower than the target density, the halftone process is not executed.

  On the other hand, as a method of measuring the toner consumption amount, there is a method of predicting the toner consumption amount from the value of the multi-value image data of each color plane before the halftone process.

  As described above, when the toner consumption is measured by the method of predicting the toner consumption from the value of the multi-valued image data of each color plane before the halftone process as described above, the trailing edge is changed according to the change with time of the development process characteristic. When halftone processing for reducing accumulation is turned on / off, an error in the measured value of toner consumption increases due to the on / off of the halftone processing.

  The present invention has been made in view of the above problems, and even if halftone processing for reducing trailing edge accumulation is turned on / off in accordance with a change in development process characteristics with time, the measured value of toner consumption is measured. It is an object of the present invention to obtain an image forming apparatus and a toner consumption calculation method that reduce errors.

An image forming apparatus according to the present invention includes a halftone processing unit that performs halftone processing on image data, and a count processing unit that counts the density of the image data before the halftone processing to predict a toner consumption amount With. The count processing unit corrects the density count value of the image data in accordance with the presence / absence of the halftone process for the solid portion. The count processing unit is (a) a count value of the density of the image data at the edge portion of the image data when the halftone processing is performed on the solid portion, and (b) the above-described case when the halftone processing is performed on the solid portion. (D) a count value of the density of the image data at the non-edge portion of the image data; and (c) a count value of the density of the image data at the edge portion of the image data when the halftone processing is not performed on the solid portion. The density count value of the image data in the non-edge portion of the image data when the halftone process is not performed on the solid portion is corrected with correction coefficients having different values.

In the toner consumption calculation method according to the present invention, the density of image data before halftone processing is counted, and the density count value of the image data is corrected according to the presence or absence of the halftone processing with respect to a solid portion. The toner consumption is predicted based on the count value later. When correcting the density count value of the image data in accordance with the presence / absence of the halftone process for the solid part, (a) the image data at the edge part of the image data when the halftone process is performed for the solid part The density count value of the image data, (b) the density count value of the image data at the non-edge portion of the image data in the case where the halftone processing is performed on the solid portion, and (c) the case where the halftone processing is not performed on the solid portion And (d) a count value of the density of the image data in the non-edge portion of the image data when the halftone process is not performed on the solid portion, Corrections are made using correction factors having different values.

  According to the present invention, it is possible to obtain an image forming apparatus that can reduce an error in a measured value of toner consumption even when halftone processing for reducing trailing edge accumulation is turned on / off according to a change in development process characteristics with time. .

  These and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a diagram showing an example of the correction coefficient for the density count value used by the count processing unit 32 in FIG. FIG. 4 is a diagram for explaining the change over time in the development density characteristics of the developing device and the presence or absence of a halftone in the solid portion in the image forming apparatus shown in FIGS. 1 and 2. FIG. 5 is a diagram for explaining calculation coefficients used for calculation of the density count value of halftone image data in the image forming apparatus shown in FIGS. 1 and 2. FIG. 6 is a diagram for explaining a rear end reservoir. FIG. 7 is a diagram for explaining reduction of rear end accumulation by halftone processing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is an apparatus having an electrophotographic printing function, such as a printer, a facsimile machine, a copying machine, or a multifunction machine.

  The image forming apparatus of this embodiment has a tandem color developing device. The color developing device includes photosensitive drums 1a to 1d, exposure devices 2a to 2d, and developing units 3a to 3d. The photoconductor drums 1a to 1d are four-color photoconductors of cyan, magenta, yellow, and black. For example, the photosensitive drums 1a to 1d are made of amorphous silicon, and the developing device performs development by a touch-down development method. For this reason, it has a development characteristic in which a rear end accumulation occurs.

  The exposure devices 2a to 2d are devices that form electrostatic latent images by irradiating the photosensitive drums 1a to 1d with laser light while scanning. The laser beam is scanned in a direction (main scanning direction) perpendicular to the rotation direction (sub-scanning direction) of the photosensitive drums 1a to 1d. The exposure apparatuses 2a to 2d have a laser scanning unit including a laser diode that is a light source of laser light and an optical element (lens, mirror, polygon mirror, etc.) that guides the laser light to the photosensitive drums 1a to 1d.

  Further, around the photosensitive drums 1a to 1d, a charger such as a scorotron, a cleaning device, a static eliminator and the like are arranged. The cleaning device removes residual toner on the photosensitive drums 1a to 1d after the primary transfer, and the static eliminator neutralizes the photosensitive drums 1a to 1d after the primary transfer.

  The developing units 3a to 3d have toner containers filled with toners of four colors of cyan, magenta, yellow and black, and attach the toners to the electrostatic latent images on the photosensitive drums 1a to 1d. Form an image. The toner constitutes a developer together with the carrier, and an external additive such as titanium oxide is further added.

  The photosensitive drum 1a, the exposure device 2a, and the developing unit 3a develop magenta, and the photosensitive drum 1b, the exposure device 2b, and the developing unit 3b develop cyan, the photosensitive drum 1c, and the exposure device 2c. The developing unit 3c performs yellow development, and the photosensitive drum 1d, the exposure device 2d, and the developing unit 3d perform black development.

  The intermediate transfer belt 4 is an annular image carrier (intermediate transfer member) that comes into contact with the photosensitive drums 1a to 1d and primarily transfers the toner images on the photosensitive drums 1a to 1d. The intermediate transfer belt 4 is stretched around the driving roller 5 and circulates in the direction from the contact position with the photosensitive drum 1d to the contact position with the photosensitive drum 1a by the driving force from the driving roller 5.

  The transfer roller 6 brings the conveyed paper into contact with the intermediate transfer belt 4 and secondarily transfers the toner image on the intermediate transfer belt 4 to the paper. The sheet on which the toner image has been transferred is conveyed to the fixing device 9 and the toner image is fixed on the sheet.

  The roller 7 has a cleaning brush, and the cleaning brush is brought into contact with the intermediate transfer belt 4 to remove the toner remaining on the intermediate transfer belt 4 after the transfer of the toner image onto the paper.

  The sensor 8 irradiates the intermediate transfer belt 4 with a light beam, and detects reflected light from the surface of the intermediate transfer belt 4 or a toner pattern on the surface. For example, the sensor 8 irradiates a predetermined region of the intermediate transfer belt 4 with light when detecting toner density, detects reflected light of the light, and outputs an electrical signal corresponding to the amount of light.

  FIG. 2 is a block diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention. As illustrated in FIG. 2, the image forming apparatus includes a communication device 11, an arithmetic processing device 12, and a printing device 13.

  The communication device 11 can be connected to a host device via a network or a peripheral device interface, and performs data communication using a predetermined communication protocol.

  The arithmetic processing unit 12 includes an ASIC (Application Specific Integrated Circuit) and / or a computer, and implements various processing units with hardware and / or software. The computer has a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., loads a program from a storage device (not shown), ROM, etc. to the RAM, and executes the program on the CPU. By doing so, various processing units are realized by software.

  The printing apparatus 13 is an internal device that prints a document image with a mechanical configuration as shown in FIG.

  In this embodiment, the processing unit 12 implements processing units such as an operating system (not shown), a communication processing unit 21, a rendering unit 22, a controller 23, and an image processing unit 24.

  The communication processing unit 21 is a processing unit that controls the communication device 11 to execute data communication with a host device or the like. For example, the communication processing unit 21 receives document data as a print request from the host device.

  The rendering unit 22 receives a print request based on a user operation on the operation panel or a print request supplied from the host device, and executes a print job corresponding to the request. For example, when document data in a predetermined data format such as PDL (Page Description Language) or PDF (Portable Document Format) is received as a print request from the host device, the rendering unit 22 generates bitmap image data from the document data. Is generated. This bitmap image data is, for example, 8-bit RGB data. When document data of bitmap data is received from the host device, the rendering unit 22 uses the document data as it is as image data.

  The controller 23 is a processing unit that monitors and controls an internal device such as the printing apparatus 13. The controller 23 controls a toner source development, transfer, and fixing by controlling a driving source (not shown) that drives the above-described roller, a bias application circuit that applies a development bias and a primary transfer bias, and exposure devices 2a to 2d. And a processing circuit for executing paper feeding, printing, and paper ejection. The developing bias is applied between the photosensitive drums 1a to 1d and the developing units 3a to 3d, respectively, and the primary transfer bias is applied between the photosensitive drums 1a to 1d and the intermediate transfer belt 4, respectively.

  The image processing unit 24 performs predetermined image processing such as color conversion (for example, color conversion from RGB data to CMYK data), gamma correction, and halftone processing on the image data, and print data (for example, Binarized print image data) is generated for each color plane. The image processing unit 24 includes a color conversion unit 31, a count processing unit 32, and a halftone processing unit 33.

  The color conversion unit 31 performs color conversion (here, color conversion from RGB data to CMYK data corresponding to the toner color) on the image data generated by the rendering unit 22.

  The count processing unit 32 counts the density of image data before halftone processing for each color plane (here, CMYK planes) to predict the toner consumption amount. That is, the count processing unit 32 accumulates the density (that is, the pixel value) for each pixel, and predicts the toner consumption based on the accumulated value. Then, the count processing unit 32 corrects the density count value of the image data in accordance with the presence or absence of the halftone process for the solid portion in the image data. If the density of the object in the image data is constant, the product of the density and the number of dots (number of pixels) of the object may be used as the density count value.

  The count processing unit 32 includes: (a) the count value of the density of the image data at the edge of the image data when the halftone processing unit 33 performs halftone processing on the solid portion; and (b) the halftone processing unit 33 is solid. The count value of the density of the image data at the non-edge portion of the image data when the halftone processing is performed on the portion, and (c) the edge portion of the image data when the halftone processing portion 33 does not perform the halftone processing on the solid portion And (d) the count value of the density of the image data at the non-edge portion of the image data when the halftone processing unit 33 does not perform the halftone processing for the solid portion. Correct with different correction factors.

  Therefore, the count processing unit 32 calculates the toner consumption amount according to the following equation.

  (Toner consumption) = (conversion coefficient) × {(non-edge portion density count value) × (non-edge portion correction coefficient) + (edge portion density count value) × (edge portion correction coefficient)}

  The conversion coefficient is a coefficient for converting the density count value into the toner consumption amount.

  FIG. 3 is a diagram showing an example of the correction coefficient for the density count value used by the count processing unit 32 in FIG. In the example shown in FIG. 3, (a) when the halftone processing unit 33 performs halftone processing on a solid portion, the correction coefficient of the count value of the density of the image data at the edge portion of the image data is 1.5, (B) When the halftone processing unit 33 performs halftone processing on the solid portion, the correction coefficient of the density count value of the image data of the non-edge portion of the image data is 1.2, and (c) halftone processing When the unit 33 does not perform halftone processing on the solid portion, the correction coefficient of the density count value of the image data at the edge portion of the image data is 1.3, and (d) the halftone processing unit 33 performs processing on the solid portion. When the halftone process is not performed, the correction coefficient of the density count value of the image data at the non-edge portion of the image data is 1.0.

  Note that the count processing unit 32 detects the edge of the solid part in the image of each color plane, determines an area having a predetermined pixel width (for example, a few pixels) on the high density side of the edge as an edge part, and otherwise The solid portion (that is, the inside of the edge portion) is determined as a non-edge portion.

  FIG. 4 is a diagram for explaining the change over time in the development density characteristics of the developing device and the presence or absence of a halftone in the solid portion in the image forming apparatus shown in FIGS. 1 and 2. As shown in FIG. 4, when the solid maximum density can be adjusted to a density higher than the target density, the solid maximum density is set to the target density by reducing the density by halftone processing for reducing the trailing edge accumulation. The When the solid maximum density cannot be adjusted to a density higher than the target density due to the change with time, the solid maximum density is made close to the target density without performing the halftone process for reducing the trailing edge accumulation.

  Therefore, the count processing unit 32 determines that the halftone process for the solid portion is not performed when the density of the solid portion is less than the target density for each color plane in the density calibration or the like, and If the density is the target density, it is determined that halftone processing is being performed on the solid portion.

  The halftone processing unit 33 performs halftone processing on the image data after color conversion by a predetermined halftone method.

  In the density calibration, when the solid maximum density is set to the target density by adjusting the solid maximum density to a density higher than the target density and then performing the halftone process, the halftone processing unit 33 performs the rear end. In order to reduce accumulation, halftone processing is performed on the solid portion of each plane of the image data after color conversion. On the other hand, in the density calibration, when the maximum density that can be developed is equal to or less than the target density, the halftone processing unit 33 does not perform the halftone process on the solid part in each plane of the image data after color conversion.

  Next, the operation of the image forming apparatus will be described.

  The rendering unit 22 generates image data from the print request, and the color conversion unit 31 performs color conversion from the image data generated by the rendering unit 22 to image data corresponding to the toner color.

  First, the count processing unit 32 determines, for each color plane, whether or not halftone processing is performed on the solid portion for the purpose of reducing the trailing edge accumulation, and the above-described correction coefficient ( Edge portion correction coefficient and non-edge portion correction coefficient).

  Here, it is assumed that the solid portion has the maximum density.

  Next, the count processing unit 32 calculates, for each color plane, the density count value (total density value) of the edge part in the solid part and the density count value (total density value) of the non-edge part in the solid part.

  Then, the count processing unit 32 calculates the toner consumption amount for each color plane according to the above formula.

  In addition, for the halftone solid part (that is, the solid part less than the maximum density), the count processing unit 32 specifies a calculation coefficient corresponding to the density (data value) of the solid part and calculates it as the solid part of the maximum density. By multiplying the calculated density count value by the calculation coefficient, the density count value at the density of the halftone solid portion is calculated. FIG. 5 is a diagram for explaining calculation coefficients used for calculation of the density count value of halftone image data in the image forming apparatus shown in FIGS. 1 and 2. The count processing unit 32 has data (table or function) indicating conversion characteristics as shown in FIG. 5, and specifies a calculation coefficient corresponding to the density (data value) of the solid portion.

  In this way, the toner consumption amount of each toner color is calculated for each page. For example, based on the toner consumption calculated in this way, the total toner consumption after the replacement of the toner cartridge is calculated, and when it is determined that the toner amount in the toner cartridge has become less than a predetermined value, A warning is displayed on an operation panel (not shown).

  On the other hand, the halftone processing unit 33 performs halftone processing on the solid part of each color plane of the color-converted image data as necessary.

  Thereafter, the controller 23 controls the printing device 13 to print an image based on the print image data after the image processing by the image processing unit 24.

  As described above, according to the above embodiment, the halftone processing unit 33 performs halftone processing on image data. The count processing unit 32 counts the density of the image data before the halftone process and predicts the toner consumption. Then, the count processing unit 32 corrects the density count value of the image data in accordance with the presence / absence of the halftone process for the solid portion.

  Thereby, even if the halftone processing for reducing the trailing edge accumulation is turned on / off according to the change in the development process characteristics with time, the error of the measured value of the toner consumption is reduced.

  Various changes and modifications to the above-described embodiment will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. That is, such changes and modifications are intended to be included within the scope of the claims.

  The present invention is applicable to, for example, an image forming apparatus.

32 Count processing unit 33 Halftone processing unit

Claims (4)

A halftone processing unit that performs halftone processing on image data;
A count processing unit that counts the density of the image data before the halftone process and predicts a toner consumption amount,
The count processing unit corrects the density count value of the image data in accordance with the presence or absence of the halftone process for the solid part ,
The count processing unit is (a) a count value of the density of the image data at the edge portion of the image data when the halftone processing is performed on the solid portion, and (b) the above-described case when the halftone processing is performed on the solid portion. (D) a count value of the density of the image data at the non-edge portion of the image data; and (c) a count value of the density of the image data at the edge portion of the image data when the halftone processing is not performed on the solid portion. Correcting the count value of the density of the image data of the non-edge portion of the image data when there is no halftone processing for the solid portion, with correction coefficients having different values, respectively.
An image forming apparatus. When the density of the solid part is less than the target density, the count processing unit determines that the halftone process for the solid part is not performed, and when the density of the solid part is the target density, the solid part the image forming apparatus according to claim 1 Symbol placement and judging the halftone processing is performed for. Further comprising a developing device having a developing characteristic in which rear end accumulation occurs;
The halftone processing unit performs halftone processing on the solid portion of the image data in order to reduce trailing edge accumulation;
The image forming apparatus according to claim 1 or claim 2 wherein. Count the density of the image data before halftone processing,
According to the presence or absence of the halftone process for the solid portion, the density count value of the image data is corrected,
Predict toner consumption based on the corrected count value ;
When correcting the density count value of the image data in accordance with the presence / absence of the halftone process for the solid part, (a) the image data at the edge part of the image data when the halftone process is performed for the solid part The density count value of the image data, (b) the density count value of the image data at the non-edge portion of the image data in the case where the halftone processing is performed on the solid portion, and (c) the case where the halftone processing is not performed on the solid portion And (d) a count value of the density of the image data in the non-edge portion of the image data when the halftone process is not performed on the solid portion, Correct each with a different correction factor,
A toner consumption calculation method characterized by the above.

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