JP2008164698A - Image forming method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which image data is developed on a recording material, such as recording paper, with a developing material such as toner, the apparatus being designed so as to reduce consumption of the developing material without degrading image recognizability significantly. <P>SOLUTION: A selecting part 30 switches a mode switching part 20 based on a user operation read by a setting reading part 29, a quantity of remaining toner read by a remaining toner quantity reading part 28, and the result of the determination of solid or non-solid, determined by a solid determining part 25. Consequently, a color profile P1 for an output image in a regular mode or a color profile P2 for an output image in a toner save mode is set for PGB→CMYK altering part 26. The PGB→CMYK conversion part 26 carries out color alteration and, in the toner save move, corrects image data so that the density of a solid portion is low. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a save mode of a developer such as toner and an image forming method thereof, and more particularly to an apparatus capable of forming a full color image.

A typical example of an image forming apparatus having the toner save mode is disclosed in Japanese Patent Application Laid-Open No. H10-228707. According to the prior art, when the user changes the color gamut (density change) through the operation unit, the potential of the developing sleeve is controlled according to the color gamut (density value) set and changed by the control unit. When the development bias voltage, which is a potential difference between the developing unit and the photosensitive drum, is changed, and the printing is performed with the changed development bias voltage, the gradation of the output image is changed and set. By creating a tone correction table that provides the target tone according to the user, the user can change the print density range according to the printing application while realizing high quality image quality (toner save mode Is realized). In other conventional technologies, the density range is shifted not by adjusting the developing bias but by reducing the amount of developer supplied or by thinning out dots (to achieve toner save by reducing the density). Is generally done.
JP 2005-43445 A

  In the above-described conventional technology, when the toner save mode is selected, the density is uniformly reduced (toner consumption is reduced). Therefore, although Patent Document 1 is devised so as not to impair gradation expression by creating a gradation correction table corresponding to the set density range and converting the gradation of the image to be printed, Depending on the type of data, there is a problem that recognition is greatly impaired. For example, for images that require high definition, such as photographs, the density range is narrowed, resulting in no sharpness (contrast) on the screen. For presentation materials and test prints, lines of drawings and text can be used regardless of color. Deterioration of information, such as the width not being accurately reproduced, becomes a problem.

  An object of the present invention is to provide an image forming method and apparatus capable of reducing the consumption of developer without significantly degrading the image recognizability.

  The image forming method of the present invention is a method for visualizing image data on a recording material with a developer, a step of extracting a solid part from input image data, and a threshold value determined in advance by the area of the extracted solid part Determining whether or not it is above, and correcting the image data so that the density of the solid portion becomes light when it is determined that the area of the solid portion is greater than or equal to the threshold value. It is characterized by that.

  The image forming apparatus of the present invention is an image forming apparatus in which image data is visualized on a recording material with a developer, and an extraction unit that extracts a solid portion from input image data, and the extraction unit extracts A solid image determination unit that determines whether or not the area of the solid portion that has been determined is greater than or equal to a predetermined threshold, and when the solid image determination unit determines that the area of the solid portion is greater than or equal to the threshold And a correction unit that corrects the image data so that the density of the solid portion is reduced.

  According to the above configuration, in the image forming method and apparatus in which image data is visualized on a recording material such as recording paper with a developer such as toner, the extraction unit extracts a solid portion from the input image data. If the solid image determination unit determines that the area of the extracted solid portion is equal to or greater than a predetermined threshold value, the correction unit enters a save mode for a developer such as toner so that the density of the solid portion is reduced. The image data is corrected.

  Therefore, it is possible to reduce the consumption of the developer without significantly degrading the image recognizability.

  Furthermore, the image forming apparatus of the present invention determines a remaining amount detection unit that detects the remaining amount of the developer, and whether or not the remaining amount of the developer is equal to or greater than a predetermined threshold by the remaining amount detection unit. And a remaining amount determination unit that pauses the correction operation in the correction unit when the threshold value is equal to or greater than the threshold value.

  According to the above configuration, the remaining amount determination unit causes the correction unit to perform the developer save mode in a state where the remaining developer is sufficiently remaining from the remaining amount of the developer detected by the remaining amount detection unit. By avoiding this, faithful density (color in the case of full color) can be reproduced.

  The image forming apparatus according to the present invention further includes a file determination unit that determines whether the input image data is photo data or electronically created data, and if the input image data is photo data, pauses the correction operation in the correction unit. It is further provided with the feature.

  According to the above configuration, when the input image data is photographic data regardless of the remaining amount of the developer, the file determination unit prevents the correction unit from performing the developer save mode, Faithful density (color in the case of full color) can be reproduced.

  In the image forming method and apparatus of the present invention, as described above, in the image forming method and apparatus in which image data is visualized on a recording material such as recording paper with a developer such as toner, the extraction unit inputs If a solid part is extracted from the image data, and the solid image determination unit determines that the area of the extracted solid part is equal to or greater than a predetermined threshold, the correction unit enters a save mode for a developer such as toner, and the solid part is determined. The image data is corrected so that the density of the portion becomes light.

  Therefore, it is possible to reduce the consumption of the developer without significantly degrading the image recognizability.

  Furthermore, as described above, in the image forming apparatus of the present invention, when the developer is sufficiently remaining from the remaining amount of the developer detected by the remaining amount detection unit, the remaining amount determination unit includes the correction unit. Prevent the developer from going into save mode.

  Therefore, faithful density (color in the case of full color) can be reproduced.

  Further, as described above, in the image forming apparatus of the present invention, when the input image data is photographic data regardless of the remaining amount of the developer, the file determination unit performs a developer save mode on the correction unit. Do not let them.

  Therefore, faithful density (color in the case of full color) can be reproduced.

  FIG. 1 is a longitudinal sectional view showing a mechanical configuration of a printer 1 which is an image forming apparatus according to an embodiment of the present invention. The printer 1 includes a sheet feeding cassette 201, a sheet feeding roller 202, a transfer roller 203, an intermediate transfer body roller 204, a photosensitive drum 205, an exposure device 206, and developing devices 207Y and 207M for yellow, magenta, cyan, and black colors. , 207C, 207K, a fixing roller 208, and a discharge tray 210.

  The photosensitive drum 205 is uniformly charged by a charging device (not shown) while rotating in the direction of the arrow. The exposure device 206 converts a modulation signal generated based on image data input from a personal computer or the like into a laser beam and outputs the laser beam, and forms an electrostatic latent image on the photosensitive drum 205 for each color. The developing devices 207Y, 207M, 207C, and 207K supply toner of each color to the photosensitive drum 205 to form a toner image for each color. The intermediate transfer roller 204 is transferred with the toner image of each color from the photosensitive drum 205, and a color toner image is formed on the intermediate transfer roller 204.

  On the other hand, the paper feeding roller 202 pulls out the recording paper from the paper feeding cassette 201 in which the recording paper is stored, and feeds the recording paper to the transfer roller 203. The transfer roller 203 transfers the toner image on the intermediate transfer body roller 204 onto the conveyed recording paper, and the fixing roller 208 heats and fixes the transferred toner image on the recording paper. Thereafter, the recording paper is discharged to the discharge tray 210.

  FIG. 2 is a block diagram illustrating an electrical configuration of the printer 1. The printer 1 generally includes an image processing unit 21, a printer unit 31, a control unit 41, an operation panel unit 51, a network I / F unit 71, a parallel I / F unit 72, and a serial I / F unit 73. The printer 1 and the HDD 74 are provided. The operation panel unit 51 gives an operation command (command) by the user to the control unit 41. The operation panel unit 51 includes a display unit 52 and an operation key unit 53.

  The image processing unit 21 performs various image processing on the image data. For example, the image processing unit 21 performs various image processing (processing) such as predetermined correction processing such as level correction and γ correction, compression or expansion processing of image data, enlargement or reduction processing, and the like on the image data. . Further, the image processing unit 21 performs density correction of image data as will be described later in the toner save mode. The image processing unit 21 includes an image memory 22 and stores the processed image data or the like in the image memory 22 or outputs it to the printer unit 31.

  The printer unit 31 receives image data received from an external personal computer or the like via the network I / F unit 71 after the image processing unit 21 performs a predetermined process, and then applies the corresponding image to a predetermined recording sheet. It is something to print. The printer unit 31 includes a paper transport unit 32 having a paper feed cassette and paper feed rollers, an image transfer unit 33 having an intermediate transfer body roller, a photosensitive drum, an exposure device, a developing device, etc., a transfer unit having a transfer roller, etc. 34, and a fixing unit 35 having a fixing roller and the like. Specifically, the paper transport unit 32 transports the recording paper to the image forming unit 33, the image forming unit 33 forms a toner image corresponding to the image data, and the transfer unit 34 transfers the toner image to the recording paper. The fixing unit 35 fixes the toner image on the recording paper to form an image.

  The control unit (control unit) 41 is a RAM (Random Access Memory) or a ROM (Read Only Memory) that stores a program that defines the operation of the CPU in a CPU (Central Processing Unit) (not shown). In addition, peripheral devices such as a RAM for temporarily storing data and a nonvolatile storage unit are included. Thus, the control unit 41 controls the entire printer 1 in accordance with the instruction information received by the operation panel unit 51 and the like, and detection signals from sensors provided in various parts of the printer 1. More specifically, the control unit 41 functions as the printer controller 44.

  The program can be supplied through a recording medium such as a ROM or a CD-ROM, or can be supplied through a transmission medium such as a network connected to the network I / F unit 71. The transmission medium is not limited to a wired transmission medium, and may be a wireless transmission medium. The transmission medium includes not only a communication line but also a relay device that relays the communication line, for example, a communication link such as a router.

  When the program is supplied through the ROM, the ROM in which the program is recorded is mounted on the control unit 41 so that the program can be executed by the CPU. When the program is supplied through a CD-ROM, the CD-ROM reader can be connected to the parallel I / F unit 72, for example, and transferred to the RAM, so that the program can be executed by the CPU. When the program is supplied through a transmission medium, the program received through the network I / F unit 71 can be transferred to the RAM for execution by the CPU.

  The network I / F unit 71 uses a network interface (for example, 10 / 100Base-TX) or the like, and controls transmission / reception of various data to / from a user personal computer connected via the network. . The parallel I / F unit 72 receives print data or the like from an external device or the like by parallel transmission in which data is transmitted in units of a plurality of bits using a plurality of signal lines using a high-speed bidirectional parallel interface (for example, conforming to IEEE 1284). It is to be equal. The serial I / F unit 73 uses a serial interface (for example, RS-232C) or the like, and receives various data from an external device or the like by serial transmission that sequentially transmits data bit by bit using a single signal line. To do.

  FIG. 3 is a functional block diagram of a portion according to the present invention in the image processing unit 21 of the printer 1 configured as described above. The image processing unit 21 according to the present invention includes a color profile P1 for an output image in a normal mode and a color profile P2 for an output image in a toner save mode, an input image data analysis unit 23, and a solid part. Detection unit 24, solid coating determination unit 25, RGB → CMYK conversion unit 26, output image data formation unit 27, toner remaining amount reading unit 28, setting reading unit 29, mode selection unit 30, and mode switching Unit 20.

  The input image data is expanded into one screen data in the input image data analysis unit 23 and analyzed for each block having a predetermined number of pixels. From the analysis result, a solid part detection unit which is an extraction unit 24, a solid portion having a substantially equal density in the adjacent portion is extracted, and a solid coating determination unit 25, which is a solid image determination unit, has a density equal to or higher than a predetermined threshold and the number of pixels in the solid portion. Is equal to or greater than a predetermined ratio of the number of pixels in the block, it is determined that the color is solid, and the determination result is input to the selection unit 30.

  Specifically, as shown in FIG. 4, the solid part detection unit 24 extracts a solid part in which the density of the adjacent parts is almost equal, obtains the area (X) thereof as indicated by the reference sign 24 a, and the reference sign. As indicated by 24b, the respective densities of C, M, and Y in the solid portion are obtained. On the other hand, in the solid coating determination unit 25, first, in the calculation unit 25a, the area (X) of the detected solid portion and the respective densities of C, M, and Y used for the solid portion are the darkest. The product value (Z) with the density value (50% of Y in the example of FIG. 4) is calculated, and then the product value (Z) is determined in the determination unit 25b by the threshold value (Y ), And it is determined that the paint is solid if it is equal to or greater than the threshold (Y).

  In this way, regardless of the product value (Z) of the density value and the area (X), the pixel density (X) having a predetermined density, for example, 30% or more, is simply compared with the threshold value of the area. For example, it may be determined that the solid color is 80% or more of the block. However, by determining from the product value (Z) as described above, it can be ignored if it is a thin and wide portion or a region that is dark but has a small area. However, even if the concentration is high, it cannot be said that there is a difference, and preferably, by incorporating a parameter of concentration variation (density fluctuation range), control with higher accuracy can be performed.

  On the other hand, the selection unit 30 detects the setting in the operation panel unit 51 read by the setting reading unit 29 and the setting transmitted prior to the printer data and the image forming unit 33 of the printer unit 31. Then, the remaining toner amount of each color C, M, Y, K in the developing devices 207Y, 207M, 207C, 207K read by the remaining toner amount reading unit 28 is input.

  From these input results, the selection unit 30 switches the mode switching unit 20 so that either the color profile P1 of the output image in the normal mode or the color profile P2 for the output image in the toner save mode is changed from RGB → CMYK. This is set in the conversion unit 26. The RGB → CMYK conversion unit 26 serving as a correction unit uses the set color profile P1 or P2 to perform color conversion of the input image data developed by the input image data analysis unit 27 and, if necessary, will be described later. The output image data forming unit 27 outputs the density correction to the image forming unit 33 of the printer unit 31.

  Table 1 and FIG. 5 show an example of toner consumption for each printing rate in the normal mode and the toner save mode. As described above, in the present embodiment, in the toner save mode, image formation is performed with half of the toner consumption amount in the normal mode.

  FIG. 6 is a flowchart for explaining color conversion and density correction operations using the RGB → CMYK conversion unit 26 from the mode switching by the selection unit 30. First, in the present embodiment, when the toner save mode key 404 of the operation unit 400 is operated when switching between the normal mode and the toner save mode, the following modes can be selected by the touch panel 401. The first is a mode for fixing to the normal mode, the second is a mode for forcibly shifting to the toner save mode, the third is a mode for automatically shifting to the toner save mode from the remaining amount of toner, Is a mode for automatically shifting to the normal mode (forcibly suspending the toner save mode) if it is a photographic image. Further, a fifth mode may be set in which it is possible to select whether to prioritize the remaining amount of toner or whether the image is a photographic image (in FIG. 6, priority is given to a photographic image).

  In step S1, various settings such as a threshold value for the remaining amount of toner, which will be described later, and the threshold value (Y) for solid coating determination are performed. In step S2, the input image data analysis unit 23 displays one screen of input image data. And is analyzed for each block having a predetermined number of pixels.

  Subsequently, in steps S <b> 3 to S <b> 6, the mode determination is performed in the selection unit 30 from the operation on the operation unit 400 read by the setting reading unit 29. First, in step S3, it is determined whether or not the image is fixed in the normal mode. If so, the process proceeds to step S11, and the RGB → CMYK conversion unit 26 performs color conversion using the color profile P1 of the output image in the normal mode. The output image data is generated and output from the output image data forming unit 27 to the image forming unit 33 of the printer unit 31 in step S12.

  If the normal mode is not fixed in step S3, the process proceeds to step S4, where it is determined whether or not the toner save mode is set. The process proceeds to S21 and subsequent steps. If the toner save mode is not set in step S4, the remaining amount of any one of C, M, Y, and K is determined in advance in step S5 from the reading result by the remaining toner amount reading unit 28; For example, it is determined whether or not it is 1/3 or more. If so, it is determined that all the remaining amount of toner is sufficient, and the process proceeds to the normal mode processing from step S11. If not, the process proceeds to step S6. . In step S6, it is determined whether or not the input image data is photo data. If the input image data is photo data, the process proceeds to normal mode processing from step S11 onward. If the input image data is not photo data, toner save from step S21 onward is executed. Move on to mode processing. Whether or not the data is photo data can be determined from the number of colors used, for example. Specifically, when each color data of RGB is expressed by 8 bits, that is, 256 gradations, the number of colors that can be expressed is about 16 million colors. However, if the number of colors actually used is 1000 or less, It is determined that the data is. Thus, even if the toner save mode is not set, if the normal mode is not fixed, the remaining amount of toner is small, and if it is not photo data, the process is performed in the toner save mode.

  In the toner save mode, the block is divided into blocks having a predetermined number of pixels in step S21. In step S22, the solid part detection unit 24 extracts a solid part for a certain block. In step S23, the solid coating determining unit 25 calculates the product value (X) of the detected area (X) of the solid portion and the darkest density value of each of C, M, and Y used in the solid portion. Z) is calculated, and in step S24, the product value (Z) is compared with the threshold value (Y). If it is equal to or greater than the threshold (Y), it is determined that the color is solid. In step S25, the RGB → CMYK conversion unit 26 performs color conversion and density correction on the color profile P2 of the output image in the toner save mode, and outputs the output image. When the data is created and is less than the threshold value, it is determined that the color is not solid, and in step S26, the RGB → CMYK conversion unit 26 performs color conversion with the color profile P1 of the output image in the normal mode, and outputs image data. Is created. From steps S25 and S26, the process proceeds to step S27, where it is determined whether or not there is a solid paint portion for all the blocks. If there is a block that has not yet been determined, the process returns to step S22. If the next block is determined and all blocks have been determined, the process proceeds to step S31.

  In performing the block division in step S21, the entire screen is not sequentially divided into blocks each having a predetermined number of pixels as described above. Even if the number of pixels is the same, adjacent pixels are not divided. Arbitrary sections may be cut out from the entire screen with a region having a small density variation as one block. In that case, the size of the block may be appropriately changed.

  In step S31, it is determined whether or not the remaining amount of C toner has become a predetermined threshold, for example, ¼ or less. If so, in step S32, the distribution of the C toner is further adjusted, and the process proceeds to step S33. If not, the process proceeds directly to step S33. The adjustment of the toner distribution is performed in order to further lower the toner density of the color when the remaining amount of toner becomes small. The density of the color is determined from the data created in steps S25 and S26. Is, for example, uniformly reduced by 10%. In step S33, the remaining amount of the M toner is determined in the same manner as in step S31. If the remaining amount is small, the distribution of the M toner is further adjusted in step S34 in the same manner as in step S32. Similarly, in steps S35 and S36, distribution adjustment is performed from the determination of the remaining amount of Y toner. Thus, when output image data is created even in the toner save mode, the process proceeds to step S12, and the created image data is output.

  With this configuration, if the area of the solid part is large, the toner save mode is set, and the output image data is corrected so that the density of the solid part becomes thin. Therefore, the solid area is small even if the density is high. Even if the portion or the solid area is large, the density of the portion with a low density is not changed, and the toner consumption can be reduced without significantly impairing the recognizability of the image.

  Also, when you want to print in the normal mode regardless of the remaining amount of toner, or when you want to print in the toner save mode, you can switch to those modes, for example, the color (look) of the image such as test printing has changed If there is no problem, the toner save mode can be selected to reduce the amount of toner consumption.

  Furthermore, if the mode is not selected, the mode is selected based on the remaining amount of toner and whether the image is a photographic image. Therefore, according to such a situation, the density is as faithful as possible (in the case of full color). Color) can be reproduced.

  Also, in the toner save mode, when there is toner that is extremely low (in the above example, less than ¼), adjustment is made to reduce the toner distribution amount (−10% in the above example). For example, as shown in FIG. 7, when (C, M, Y) = (30%, 30%, 50%) → (C, M, Y), (C, M, Y) = ( 20%, 30%, 50%), and further saving can be performed. The process of reducing the toner distribution amount is not limited to the correction of the image data. For example, the same processing can be performed by reducing the rotation speed of the developing roller of the developing devices 207Y, 207M, 207C, and 207K or by reducing the developing bias. An effect can be obtained.

1 is a longitudinal sectional view showing a mechanical configuration of a printer that is an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of the printer. It is a functional block diagram of the part which concerns on this invention in the image process part of the said printer. It is a functional block diagram of the composition for solid paint judging concerning one embodiment of the present invention. 6 is a graph showing an example of toner consumption for each printing rate in a normal mode and a toner save mode. 6 is a flowchart for explaining color conversion and density correction operations from the switching of the two modes. 10 is a graph for explaining a process of further reducing the toner distribution amount when the remaining amount of toner is small.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer 21 Image processing part 23 Input image data analysis part 24 Solid part detection part 25 Solid coating determination part 26 RGB-> CMYK conversion part 27 Output image data formation part 28 Toner remaining amount reading part 29 Setting reading part 30 Mode selection part 31 Printer Unit 41 Control unit 51 Operation panel unit 71 Network I / F unit 72 Parallel I / F unit 73 Serial I / F unit 205 Photosensitive drum 206 Exposure devices 207Y, 207M, 207C, 207K Developing device

Claims (4)

In a method for visualizing image data on a recording material with a developer,
Extracting a solid part from the input image data;
Determining whether the area of the extracted solid portion is equal to or greater than a predetermined threshold;
And a step of correcting the image data so that the density of the solid portion becomes light when it is determined that the area of the solid portion is equal to or greater than the threshold value. In an image forming apparatus in which image data is visualized on a recording material with a developer,
An extraction unit for extracting a solid part from input image data;
A solid image determination unit that determines whether the area of the solid portion extracted by the extraction unit is equal to or greater than a predetermined threshold;
And a correction unit that corrects the image data so that the density of the solid portion becomes light when the solid image determination unit determines that the area of the solid portion is equal to or larger than the threshold value. Image forming apparatus. A remaining amount detecting unit for detecting the remaining amount of the developer;
A remaining amount determination unit that determines whether or not the remaining amount of the developer is equal to or greater than a predetermined threshold in the remaining amount detection unit; The image forming apparatus according to claim 2, further comprising:   3. A file determination unit that determines whether the input image data is photo data or electronically generated data, and if the input image data is photo data, further includes a file determination unit that pauses the correction operation in the correction unit. Or the image forming apparatus according to 3.

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