JP2007279150A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming method, wherein the use amount of color material is reduced in a color material saving mode and deterioration in image quality is suppressed. <P>SOLUTION: When a toner saving instruction is discriminated by a toner saving discrimination part 12, a processing parameter during toner saving is set to each part, from a processing parameter storing part 18. Then, an exposing condition control part 22 controls to reduce the consumed amount of the toner by lowering laser beam amount and a fixing control part 24 controls fixing temperature of the fixing part in an image forming part 17 to be higher than in a normal mode. Thus, by increasing the degree of toner fusion, the image quality which is deteriorated by reducing of the consumed toner quantity is improved up to the image quality in a normal mode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming technique capable of forming an image in at least a normal mode and a color material saving mode in which the color material consumption is suppressed.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image using a color material has a color material save mode that can reduce the amount of color material used and the cost required for image formation. As a conventional color material saving method, for example, in Patent Document 1, a laser printer irradiates a photosensitive member with a laser printer to adjust the laser light irradiation level to reduce the density, thereby reducing the amount of toner as a coloring material attached to the photosensitive member. And a method of applying a gray screen to an image and thinning dots to reduce the amount of toner used. Patent Document 1 describes that these methods are selected for each object.

  In Patent Document 2, the amount of toner used is reduced by changing the gamma table according to the toner save rate. Further, Japanese Patent Application Laid-Open No. 2004-228561 describes that processing to uniformly reduce an image, processing to make an image only an edge, processing to reduce the image, and the like save the amount of toner used.

  Although all of these conventional color material saving methods can reduce the amount of color material used, there is a problem that the image quality deteriorates. For example, in the method of adjusting the laser light irradiation level described in Patent Document 1, the image quality becomes blurred because the density decreases. Further, in the method using the gray screen, the edge reproduction failure occurs due to the fact that the screen structure is visible particularly for characters and the like. For example, even when the density is changed, such as changing the gamma table in Patent Document 2, the screen structure appears due to the decrease in density, which causes poor reproduction such as edges. Furthermore, as described in Patent Document 3, if processing for uniformly narrowing the image is performed, the amount of information in the image details will be deleted accordingly, and there is a trade-off in reducing color material consumption. Directly connected to image quality degradation.

  As described above, all the conventional color material saving methods can reduce the amount of the color material, but have a problem that the image quality is deteriorated.

JP 2001-83845 A JP 2003-295701 A JP 2000-326594 A

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an image forming apparatus and an image forming method that reduce the amount of color material used in the color material save mode and suppress deterioration in image quality. To do.

  The present invention relates to an image forming apparatus capable of forming an image in at least a normal mode and a color material save mode, and an image forming method thereof. In the color material save mode, the amount of color material used in the image forming unit is reduced as compared with the normal mode. In addition, an image is formed by controlling so as to increase the degree of melting of the color material by the fixing unit. Increasing the degree of melting of the color material can be realized by increasing the fixing temperature in the fixing unit, increasing the heating time, or performing the fixing a plurality of times. The amount of the color material can be reduced, for example, by changing exposure conditions, changing the charging potential or bias potential of the image carrier, or changing the density of the color material during development. Further, it is preferable that the color material reduction amount and the degree of melting of the color material by the fixing unit are changed according to the type of the recording medium.

  Furthermore, gradation characteristics, color reproduction characteristics, halftone characteristics, and the like change by reducing the amount of color material and increasing the degree of melting of the color material. These can be configured to be corrected in advance. In addition, the color material can be reduced and the melting degree of the color material can be changed by some methods, and the control can be performed according to the selected method.

  According to the present invention, the image quality deteriorated by reducing the amount of the color material is improved by increasing the degree of melting of the color material. Accordingly, there is an effect that the image quality can be maintained while reducing the amount of the color material.

  FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is an image forming apparatus, 2 is an application, 3 is a printer driver, 11 is a drawing processing unit, 12 is a toner save discrimination unit, 13 is a color reproduction processing unit, 14 is a gradation correction unit, and 15 is halftone processing. 16, an image formation control unit, 17 an image formation unit, 18 a processing parameter storage unit, 21 a charging potential control unit, 22 an exposure condition control unit, 23 a development control unit, 24 a fixing control unit, and 31 A toner save selection unit. In this example, an electrophotographic image forming apparatus using toner as a color material is shown, but the present invention is not limited to this. Here, it is assumed that the input image created by the application 2 or the like is output by the image forming apparatus 1 via the printer driver 3, and the toner save selection unit 31 of the printer driver 3 selects the execution contents of the toner save. The image printing apparatus is illustrated as notifying the execution contents of toner save together with the input image.

  The image forming apparatus 1 receives image data from the outside through a printer driver 3 or the like, forms an image on a recording medium such as paper, and outputs the image. Here, the image forming apparatus 1 includes a drawing processing unit 11, a toner save determination unit 12, a color reproduction processing unit 13, a gradation correction unit 14, a halftone processing unit 15, an image formation control unit 16, an image formation unit 17, and processing parameters. The storage unit 18 and the like are included.

  The drawing processing unit 11 draws an image according to image data received from the outside. The toner save discriminating unit 12 discriminates whether or not the toner save is designated or the designation of the toner save method according to the parameter received from the outside together with the image data. The determination result is passed to the processing parameter storage unit 18.

  The color reproduction processing unit 13 performs various color processes on the image drawn by the drawing processing unit 11. For example, color space conversion is performed to convert the toner color used for image formation into color signals. Also, conversion to a color within the color reproduction range is performed. The gradation correction unit 14 performs shading correction processing for each color component. The halftone processing unit 15 generates a pseudo halftone image by, for example, screen processing.

  The image forming control unit 16 controls each unit of the image forming unit 17 to cause the image forming unit 17 to form an image. The image forming unit 17 forms and outputs a pseudo halftone image generated by the halftone processing unit 15 on a recording medium such as paper. Here, the image forming unit 17 includes a charging unit, a laser driving unit, a developing unit, a fixing unit, and the like, and the image forming control unit 16 controls the respective units of the image forming unit 17 so that charging is performed. The voltage control unit 21 includes an exposure condition control unit 22, a development control unit 23, a fixing control unit 24, and the like.

  The processing parameter storage unit 18 holds processing parameters corresponding to a plurality of toner saving methods, selects one of the processing parameters according to the determination result by the toner save determination unit 12, and sets it in each unit. In this example, the color reproduction processing unit 13, gradation correction unit 14, halftone processing unit 15, image formation control unit 16 (charging potential control unit 21, exposure condition control unit 22, development control unit 23, fixing control unit 24). Is configured to set processing parameters.

  In the present invention, the control for reducing the toner amount in the toner save mode is performed mainly by controlling each part of the image forming unit 17. First, an example of the configuration of the image forming unit 17 will be described. A specific example of the operation in the toner save mode will be described.

  2 and 3 are explanatory diagrams of an example of the image forming unit. In the figure, 41 and 41-1 to 4 are photosensitive members, 42 and 42-1 to 4 are charging units, 43 and 43-1 to 4 are laser driving units, 44 and 44-1 to 4 are developing units, and 45 is a developing unit. A sheet conveyance path, 46 is a transfer roll, 47 is a fixing unit, and 48 is a transfer belt. The example shown in FIG. 2 shows an example of a 4-cycle image forming unit 17. After the photosensitive member 41, which is an image carrier, is charged to a predetermined charging potential by the charging unit 42, a laser beam is irradiated from the laser driving unit 43 to the photosensitive member 41 according to an image to be formed, and an electrostatic latent image is formed. Is done. Thereafter, the electrostatic latent image is developed with toner in the developing unit 44. On the other hand, a recording material such as paper on which an image is recorded is conveyed along a paper conveyance path 45, and the image developed on the photoconductor 41 is transferred onto the recording material at a contact point between the transfer roll 46 and the photoconductor 41. The This operation is repeated a plurality of times while switching the color of the toner used in the developing unit 44. The recording body onto which the images of the toners of a plurality of colors are transferred is sent to the fixing unit 47, where the toner is heated and melted and fixed to the recording body, whereby a final fixed image is obtained.

  The example illustrated in FIG. 3 illustrates an example of the tandem image forming unit 17. The basic configuration is the same as that of the 4-cycle type shown in FIG. 2, but the tandem type has a photoconductor, a charging unit, a laser driving unit, and a developing unit for each color component. The operation until an image developed with a recording material such as toner of each color is formed on the photoreceptors 41-1 to 41-4 is as described above. The recording material is conveyed along the paper conveyance path 45 and further conveyed on the transfer belt 48. Then, the toner images of the respective colors are sequentially transferred and superimposed at the contact points between the transfer belt 48 and the photoreceptors 41-1 to 41-4. In this example, after the toner images for each of the four colors are transferred and superimposed, the recording body is heated in the fixing unit 47, and the toner is fixed to the recording body. In this way, a color image is formed on the recording medium.

  Next, a specific example for maintaining image quality while suppressing toner consumption in the present invention will be described using an example of such an image forming unit 17. First, a change in output characteristics when the fixing temperature is changed in the fixing unit 47 will be described. FIG. 4 is a graph showing an example of a change in output density when the fixing temperature is changed, and FIGS. 5 and 6 are graphs showing an example of a change in the color gamut. Note that FIG. 4 shows only one color toner (for example, black (K)) among a plurality of color toners. The same applies to other color toners.

  4 to 6, the broken line indicates the case of the fixing temperature in the normal mode, and the solid line indicates the case where the fixing temperature is higher than that in the normal mode. As shown in FIG. 4, the maximum density of the formed image is higher in the maximum density Dmax_B when the fixing temperature is set higher than the maximum density Dmax_A in the normal mode. Recognize. As a result, it is possible to change characteristics such as an increase in the contrast of the output image and an expansion of the color reproduction range. On the contrary, if the same density as in the normal mode is reproduced, the density of the input image can be set low when the fixing temperature is high.

  FIG. 5 shows an example of a color reproduction range at a certain lightness. It can be seen that the color reproduction range when the fixing temperature indicated by the solid line is increased is wider than the color reproduction range in the normal mode indicated by the broken line. In particular, it can be seen that the secondary color indicated by the solid line circle has a larger color gamut than the primary color indicated by the dotted line circle.

  Further, FIG. 6 shows an example of a color reproduction range in a certain hue. Also from this figure, it can be seen that the color gamut when the fixing temperature indicated by the solid line is increased is wider than the color gamut in the normal mode indicated by the broken line. In particular, it can be seen that the color gamut is enlarged in the low lightness portion.

  In this way, if the fixing temperature is increased, the color gamut can be expanded, so if an image is formed in the same color gamut as in the normal mode, the amount of toner consumed is reduced by the narrowing of the color gamut. Is possible. In general, when the fixing temperature is increased, disadvantages such as the occurrence of gloss when the maximum density is approached occur. However, if the toner consumption is reduced and only the density and color gamut equivalent to those in the normal mode are used as in the present invention, the toner can be used in a range where no disadvantages such as gloss occur.

  Next, an example of the control of the image forming unit 17 for reducing the toner consumption will be described. Here, the change when the fixing temperature is changed in the fixing unit 47 is also shown. FIG. 7 is a graph showing an example of the relationship between the laser light quantity and the output density. Here, only one color among a plurality of color toners is shown, but the same applies to other color toners. In FIG. 7, the normal mode is indicated by a broken line, and the fixing temperature is indicated by a solid line.

  As shown in FIG. 7, when the amount of laser light is changed, the output density naturally changes. At this time, even with the same amount of laser light, the output density increases when the fixing temperature is increased. For example, when the laser light quantity is LP_A, if the fixing temperature is set higher than that in the normal mode, the output density increases by ΔD in this example. On the other hand, considering that the output density in the normal mode is maintained, the amount of laser light can be reduced by ΔLP to LP_B. That is, even if the amount of laser light is reduced, the same density can be obtained by increasing the fixing temperature. By reducing the amount of laser light, the amount of toner adhering to the surface of the photoconductor 41, which is an image carrier, can be reduced, and the amount of toner consumed can be reduced. The concentration can be obtained.

  FIG. 8 is a graph showing an example of the change in output density when the laser light quantity and the fixing temperature are changed, and FIGS. 9 and 10 are graphs showing an example of the change in the color gamut. FIG. 8 shows only one color toner (for example, black (K)) among a plurality of color toners. The same applies to other color toners.

  In the graphs shown in FIGS. 4 to 6 described above, the laser light amount is set to a value in the normal mode (for example, LP_A shown in FIG. 8). As described with reference to FIG. 7, by increasing the fixing temperature and reducing the amount of laser light, it is possible to obtain a density equivalent to that in the normal mode. FIG. 8 shows the change in the output density with respect to the input signal when the fixing temperature is increased and the amount of laser light is decreased, and the color reproduction range is shown in FIGS. 8 to 10, the case of the normal mode is indicated by a broken line, and the case where the fixing temperature is increased and the amount of laser light is reduced is indicated by a solid line.

  For example, as can be seen by comparing FIG. 4 and FIG. 8, when the fixing temperature is increased, the maximum output density is higher than that in the normal mode, but by reducing the amount of laser light, the maximum output density equivalent to that in the normal mode is obtained. Can be obtained. On the other hand, if it is sufficient to obtain the maximum output density equivalent to that in the normal mode, the laser light quantity can be reduced and the toner consumption can be reduced by increasing the fixing temperature.

  As shown in FIG. 8, the gradation characteristics are slightly different between the normal mode and the case where the fixing temperature is increased and the laser light quantity is decreased. In order to reduce such a difference in gradation characteristics, the gradation correction parameter used in the gradation correction unit 14 shown in FIG. 1 may be changed. In FIG. 1, the gradation correction unit 14 is also configured to set processing parameters from the processing parameter storage unit 18, and this configuration can cope with differences in gradation characteristics.

  Further, comparing FIG. 5 and FIG. 9, the primary color portion indicated by the dotted circle has the same density in any case as shown in FIG. However, in the secondary color portion indicated by a solid circle, the color gamut does not match and widens. This is because the fixing property to the overlapping toner of the secondary color or higher is improved by increasing the fixing temperature in the fixing unit 47. The toner consumption can be reduced even in the portion where the color gamut is enlarged. In order to reduce the amount of toner consumed in this portion, the processing parameters for the color conversion processing in the color reproduction processing unit 13 may be changed. In FIG. 1, the color reproduction processing unit 13 is also configured to set the processing parameters from the processing parameter storage unit 18, and this configuration can cope with the difference in the color reproduction range.

  Further, when FIG. 6 and FIG. 10 are compared, the color reproduction range is expanded in the low brightness range as compared with the normal mode. This is for the same reason as in FIG. 9, and it is possible to reduce the amount of toner consumed for the portion where the color reproduction range is enlarged. In this case as well, it is only necessary to change the processing parameters in the color conversion processing in the color reproduction processing unit 13, and this can cope with the difference in the color gamut.

  Thus, by raising the fixing temperature of the fixing unit 47 as compared with the normal mode, it is possible to reduce the amount of laser light and reduce the toner consumption, and to maintain the image quality. In addition, the toner consumption corresponding to the expanded portion of the color gamut by increasing the fixing temperature can be reduced.

  Although not shown in the figure, in the case of halftone reproduction, the dot reproducibility and the like may change by reducing the amount of laser light by increasing the fixing temperature as in the case of gradation reproduction. In such a case, it is possible to adjust to the normal halftone reproduction by adjusting the growth order of the screen. As a configuration for this purpose, in FIG. 1, processing parameters are also set from the processing parameter storage unit 18 to the halftone processing unit 15, and this configuration can cause differences in halftone reproduction such as dot reproducibility. Can respond. In this case, the tone characteristics may change further, but the tone correction parameters that take into account the differences in tone characteristics caused by correcting the differences in halftone reproduction as well as the differences in tone characteristics described above are applied. In addition, by performing gradation correction by the gradation correction unit 14, gradation reproduction equivalent to that in the normal mode can be maintained.

  FIG. 11 is an explanatory diagram of a specific example of the relationship between the toner usage amount and the signal value in the device-independent space under each condition. Here, an example of a color (device-independent signal Lab) output by giving a specific color signal (YMCK) to the image forming unit 17 is shown. As a specific example, it is assumed that color signals Y = 0, M = 20, C = 100, and K = 80 are given to the image forming unit 17 in the normal mode. Assume that the colors output from the image forming unit 17 at this time are L = 18.229, a = −5.672, and b = −15.784.

  Here, if the fixing temperature of the fixing unit 47 is increased without changing the color signal applied to the image forming unit 17, the color output from the image forming unit 17 is L = 18. 030, a = −9.213, b = −17.122, and the color shifts in the direction of increasing saturation. The brightness is also somewhat lower. This is because the color reproduction range has expanded in the saturation direction and the low brightness direction by increasing the fixing temperature.

  As shown in the third row of FIG. 11, by increasing the fixing temperature, reducing the amount of laser light, and correcting the difference in gradation characteristics and color reproduction range from the normal mode caused by these controls, The color output from the image forming unit 17 can be made almost equivalent to the normal mode (first stage in FIG. 11). At this time, the color signals given to the image forming unit 17 are Y = 0, M = 18, C = 100, and K = 75. This is due to correction of the color reproduction range difference and gradation characteristics by the color reproduction processing unit 13 and the gradation correction unit 14 (and the halftone processing unit 15), thereby reducing the toner consumption. be able to. As can be seen from FIG. 9 and FIG. 10, this is due to the expansion of the color gamut when the toner of the secondary color or higher is used, and there is little to reproduce the same color as in the normal mode. This is because the amount of toner used is sufficient. This can be said widely in areas where two or more toners other than this specific example are used, so that the toner consumption can be reduced in the corresponding areas. Further, by reducing the amount of laser light, the amount of toner consumed can be reduced in the image forming unit 17. Therefore, the quality of the image formed by the image forming unit 17 can be equivalent to that of the normal mode while reducing the toner consumption as a whole.

  In the above description, the case where the method of reducing the laser light quantity is used as the control in the image forming unit 17 for reducing the toner consumption has been described. As another control method, toner consumption can be reduced by controlling a charging voltage for charging the photosensitive member 41 in the charging unit 41, a bias voltage used in the developing unit 44, and the like. FIG. 12 is a graph showing an example of the relationship between the development potential and the output density. Here, only one color among a plurality of color toners is shown, but the same applies to other color toners. In FIG. 12, the normal mode is indicated by a broken line, and the fixing temperature is indicated by a solid line.

  The development potential shown in FIG. 12 is determined by the charged potential of the photoconductor 41 that is an image carrier, the potential that has been removed by exposure of the photoconductor 41, and the bias potential in the developing unit 44. Even when the developing potential changes, the output density changes as shown in FIG. Further, the relationship between the development potential and the output density varies depending on the fixing temperature. For example, the output density increases when the fixing temperature is set higher as shown by the solid line than in the normal mode shown by the broken line in FIG. To do. For example, when the developing potential in the normal mode is Vdev_A, in order to obtain the same output density as in the normal mode by increasing the fixing temperature, the developing potential may be decreased by ΔVdev to Vdev_B. When the developing potential is lowered, the amount of toner adhering to the photoconductor 41 is reduced, so that the toner consumption can be reduced. However, it is more desirable to consider changes in development latitude caused by changing the characteristics, image quality characteristics other than density (granularity, fine line reproduction, etc.), and effects on image quality defects.

  Here, an example in which the laser light quantity is changed as the exposure condition and an example in which the developing potential is changed as an example in which the charging voltage and the bias voltage are changed have been described. Of course, these are combined or other controllable parameters are set. In addition, the toner consumption may be reduced by appropriately controlling the charging, exposure, and development conditions. Further, processing parameters for the color reproduction processing unit 13, the gradation correction unit 14, and the halftone processing unit 15 according to the difference in the gradation characteristics and the color gamut changed by the control in the image forming unit 17. By switching processing parameters given from the storage unit 18, the image quality in the normal mode can be made closer.

  The amount of toner consumption can be further reduced depending on the type of recording medium. For example, even if papers are classified as the same plain paper, some papers have different densities. To reduce toner consumption, use paper that is darker and reduce the amount of toner used to make it darker than other paper so that images are formed with the same density as other paper. For example, the toner consumption can be further reduced with the same image quality.

  Up to this point, it has been described that the image quality equivalent to that in the normal mode can be maintained even when the toner consumption is reduced by controlling the temperature of the fixing unit 47 and increasing the fixing temperature. In addition to increasing the fixing temperature, several methods are conceivable as methods for maintaining the image quality equivalent to that in the normal mode when the toner consumption is reduced. For example, the same effect can be obtained by changing the process speed. This process speed is a speed at which an image is formed. In the electrophotographic system, it can be represented by a speed at which a recording medium such as paper is conveyed. When this process speed is slowed down, the time for passing through the fixing unit 47 also becomes longer. That is, it is possible to increase the amount of heat given to the toner by increasing the heating time in the fixing unit 47 and improve the degree of melting of the toner as in the case where the fixing temperature is increased. However, there are some points to consider when changing the process speed.

  FIG. 13 is a graph showing an example of a characteristic change when the process speed is changed. The horizontal axis indicates the amount of laser light, and the vertical axis indicates the potential of the photoconductor 41 that is an image carrier. In general, it is known that the laser intensity can be stably output only within a certain range, but it is not stable on the lower intensity side or higher intensity side than that range. This stable range depends on the process speed.

  For example, in FIG. 13, the range of the laser light quantity corresponding to the range in which the laser intensity is stable at the process speed in the normal mode is indicated as LPL_A. Further, a laser light amount range corresponding to a range where the laser intensity is stabilized when the process speed is halved is indicated as LPL_C. At this time, a region that is stable in LPL_A may not be included in LPL_C. In particular, for the purpose of reducing toner consumption, there is a region indicated by ΔLPL in the figure on the side where the laser light quantity is small. This range such as ΔLPL may be further expanded depending on the amount of change in process speed. In such a case, even if the laser light quantity is reduced, the laser intensity needs to be within a stable range. For example, it may be necessary to take measures such as changing the pulse width of the laser.

  In addition to this example, there may be a case where the image density fluctuates due to a change in the process speed, but this can be dealt with by a change in the processing parameters of the gradation correction unit 14, and detailed description thereof is omitted here.

  Further, as another method of maintaining the same image quality as that in the normal mode when the toner consumption is reduced, it is conceivable to perform fixing a plurality of times. For example, if you have a mechanism that can form images on both sides of the recording medium, after fixing the image after forming the image on one side, fix the back side without fixing the image to be formed on the back side. It can be performed. Similarly, for example, after forming a single-sided image, the sheet is conveyed in the reverse direction before discharging and returned to fixing, and then the fixing process is performed again, or the discharged recording medium is subjected to image forming processing again without an image. Also, it is possible to perform the fixing process a plurality of times. Furthermore, a plurality of fixing units 47 may be provided.

  By performing the fixing process a plurality of times as described above, the image quality equivalent to that in the normal mode can be obtained even when the degree of toner melting is increased and the toner consumption is suppressed.

  Next, an outline of the operation of the present invention will be described. In the configuration shown in FIG. 1, first, an input image created by the application 2 or the like is transferred to the image forming apparatus 1 via the printer driver 3. In the printer driver 3, the toner save selection unit 31 allows the user to select execution contents of toner save.

  FIG. 14 is an explanatory diagram of a specific example of a display screen for selecting toner save on the printer driver. In the figure, 51 is a toner save selection field. When an image print is instructed by the application 2 or the like, for example, a property screen of the image forming apparatus 1 as shown in FIG. 14 can be displayed to make various settings. In this example, as one of the setting items, the execution contents of toner save can be selected from the pull-down menu in the toner save selection column 51. In the example shown in FIG. 14, four options “No”, “Toner Save 1”, “Toner Save 2”, and “Toner Save 3” are prepared as options. “No” is a case where the toner save function is not used. “Toner save 1” is an option for reducing the amount of toner consumption with little deterioration in image quality according to the present invention. When this option is selected, the fixing temperature of the fixing unit 47 may be set to a high temperature to control the image quality. “Toner save 2” is also an option for reducing the amount of toner consumed by the present invention with almost no deterioration in image quality. When this option is selected, control is performed so as to maintain the image quality by reducing the process speed. Therefore, when this option is selected, the speed at which an image is formed and output decreases. “Toner save 3” performs toner save processing that has been conventionally performed, and is accompanied by deterioration in image quality. When this option is selected, it can be considered that the user is aware of the deterioration of the image quality. Therefore, for example, after performing the processing for suppressing the deterioration of the image quality as in the present invention, further consumption of toner. It is also possible to control so as to reduce. Note that the options shown in FIG. 14 and the method of presentation (display) to the user are merely examples, and an arbitrary number of options can be provided and presented to the user by any method of presentation.

  When the toner save execution content is set on such a property screen and an output is instructed, the input image and the set toner save execution content are notified to the image forming apparatus 1. When the setting on the property screen is not performed, the execution contents of the toner save are notified with a preset or default setting. In addition, the execution contents of toner save can be directly set for the image forming apparatus 1 by using a setting unit (not shown) of the image forming apparatus 1.

  15 and 16 are flowcharts showing an example of the operation according to the embodiment of the present invention. Here, a description will be given assuming that the mode (toner save mode) for suppressing the toner consumption operates according to any of the above four options including the normal mode. When a print instruction from the printer driver 3 is sent to the image forming apparatus 1, the drawing processing unit 11 of the image forming apparatus 1 performs a drawing process based on the input image in S61. In S <b> 62, the toner save determination unit 12 determines the execution contents of the toner save sent from the printer driver 3. The result of this determination is sent to the processing parameter storage unit 18, and processing parameters according to the determination result of the execution contents of toner save are set in each unit from the processing parameter storage unit 18.

  When the execution content of the toner save is “No”, the image forming process in the normal mode is performed. In this case, the color reproduction processing parameter (DLUT_A) in the normal mode is read from the processing parameter storage unit 18 to the color reproduction processing unit 13 in S63, and the color reproduction processing unit 13 performs color conversion or the like in S64. Perform the color reproduction process. In S65, the gradation correction processing parameter (LUT_A) in the normal mode is read out from the gradation correction unit 14, and in S66, the gradation correction unit 14 performs gradation correction processing. Further, in S67, halftone processing parameters such as a screen in the normal mode are read out to the halftone processing unit 15, and in S68, the halftone processing unit 15 performs halftone processing such as screen processing.

  In S69, the normal process speed (PROC_A) is set. In S70, the charging potential control unit 21 sets the image carrier potential (VH_A) in the normal mode. In S71, the exposure condition control unit 22 sets the normal mode. Set the laser light quantity (LP_A). After performing these settings, the image forming unit 17 starts irradiating the image carrier (photosensitive member 41) with laser light in S72.

  Further, the development control unit 23 adjusts the toner density of the developing device in S73, and sets the bias potential to the normal mode potential (VB_A) in S74. Then, the developing unit 44 of the image forming unit 17 develops the latent image formed on the image carrier (photosensitive member 41) with the laser beam with toner in S75 according to these settings. In S76, the developed toner image is transferred onto the recording medium. At this time, each toner image once transferred to the intermediate transfer member may be transferred from the intermediate transfer member to the recording paper.

  In S77, the fixing control unit 24 sets the fixing temperature (TMP_A) in the normal mode to the fixing unit 47 of the image forming unit 17, and in S78, the fixing unit 47 heats and melts the toner at the normal fixing temperature, Toner is fixed on the recording medium. In this way, an image is formed in the normal mode.

  If the execution content of the toner save is “Toner Save 1” in S62, the fixing temperature is increased and the laser light quantity is reduced according to the present invention, so that the toner consumption is reduced and the image quality is maintained. In this case, the color reproduction processing parameter (DLUT_B) for toner save 1 is read from the processing parameter storage unit 18 to the color reproduction processing unit 13 in S81. This processing parameter is for forming the image in the same color reproduction range as in the normal mode by reducing the toner amount only in the widened portion because the color reproduction range is widened by increasing the fixing temperature as described above. . Using this color reproduction processing parameter for toner save 1, in S64, the color reproduction processing unit 13 performs color reproduction processing such as color conversion.

  In S82, the tone correction processing parameter (LUT_B) for toner save 1 is read out to the tone correction unit 14, and in S66, the tone correction unit 14 performs tone correction processing. This is because, for example, as described with reference to FIG. 8, correction is also performed due to the difference in gradation characteristics. The gradation correction characteristic in the normal mode and the characteristic of the difference in gradation characteristic from that in the normal mode in toner save 1 are combined to generate a processing parameter for actually performing the gradation correction. May be.

  Further, in S83, halftone processing parameters such as a screen for toner save 1 are read out to the halftone processing unit 15, and in S68, the halftone processing unit 15 performs halftone processing such as screen processing. This also corresponds to the case where the dot reproducibility different from that in the normal mode may be exhibited as described above. If the halftone characteristics are not so different from those in the normal mode, halftone processing may be performed using the halftone processing parameters in the normal mode. When this halftone processing parameter is changed, the gradation characteristic also changes due to the change. Therefore, the gradation correction processing parameter set in S82 is also about the change in the gradation characteristic due to the change of the halftone processing parameter. It is necessary to consider.

  The setting of the process speed (PROC_A) in S69 and the setting of the image carrier potential (VH_A) in S70 are the same as in the normal mode. In the case of toner save 1, the exposure condition control unit 22 performs toner save in S84. The laser light quantity (LP_B) for 1 is set. This laser light quantity (LP_B) is set so as to be smaller than that in the normal mode, thereby reducing toner consumption. After performing these settings, the image forming unit 17 starts irradiating the image carrier (photosensitive member 41) with laser light in S72.

  Further, the adjustment of the toner density of the developing device in S73 and the setting of the bias potential (VB_A) in S74 are the same as in the normal mode. In accordance with these settings, the image carrier (photosensitive member 41) is irradiated with laser light in S75. The formed latent image is developed with toner. In S76, the developed toner image is transferred onto the recording medium.

  In S85, the fixing control unit 24 sets the fixing temperature (TMP_B) for toner save 1 to the fixing unit 47 of the image forming unit 17, and in S78, the fixing unit 47 heats the toner at a fixing temperature higher than normal. Melt to fix the toner on the recording medium. As a result, the image quality deteriorated by reducing the toner consumption can be improved to the image quality of the normal mode. In this way, an image is formed when “toner save 1” is designated.

  If the toner save execution content is “toner save 2” in S62, the present invention reduces the process speed to increase the fixing time, reduces the laser light quantity, and further changes the development potential in this example. Thus, reduction of toner consumption and maintenance of image quality are realized. In this case, the color reproduction processing parameter (DLUT_C) for toner save 2 is read from the processing parameter storage unit 18 to the color reproduction processing unit 13 in S91. This processing parameter is for forming the image in the same color reproduction range as that in the normal mode by reducing the toner amount only in the widened portion because the color reproduction range is widened by extending the fixing time. Using the color reproduction processing parameters for toner save 2, the color reproduction processing unit 13 performs color reproduction processing such as color conversion in S64.

  In S92, the tone correction processing parameter (LUT_C) for toner save 2 is read to the tone correction unit 14, and in S66, the tone correction unit 14 performs tone correction processing. This is also to perform correction due to the difference in gradation characteristics due to toner save. As in the case of toner save 1, the gradation correction characteristic in the normal mode and the characteristic of the difference in gradation characteristic in the normal mode in toner save 2 are combined to actually perform the gradation correction. The processing parameters may be generated.

  Further, in S93, halftone processing parameters such as a screen for toner save 2 are read out to the halftone processing unit 15, and in S68, the halftone processing unit 15 performs halftone processing such as screen processing. This is the same as in the case of toner save 1.

  Further, in S94, a process speed (PROC_C) slower than the normal mode is set for the image forming unit 17. Since the development characteristics change due to the change in the process speed, the charging potential control unit 21 sets the image carrier potential (VH_C) for toner save 2 in S95, and the exposure condition control unit 22 for toner save 2 in S96. The laser light quantity (LP_C) is set. The reason for changing the laser light quantity is due to the characteristic change when the process speed is changed as described with reference to FIG. After performing these settings, the image forming unit 17 starts irradiating the image carrier (photosensitive member 41) with laser light in S72.

  Further, the development controller 23 adjusts the toner density of the developing device in S73, and sets the bias potential to the potential (VB_C) for toner save 2 in S97. Then, the developing unit 44 of the image forming unit 17 develops the latent image formed on the image carrier (photosensitive member 41) with the laser beam with toner in S75 according to these settings. In S76, the developed toner image is transferred onto the recording medium.

  In the case of toner save 2, the fixing temperature may be the same as in the normal mode, and in S77, the fixing control unit 24 sets the same fixing temperature (TMP_A) as in the normal mode to the fixing unit 47 of the image forming unit 17. In step S78, the fixing unit 47 heats and melts the toner to fix the toner on the recording medium. At this time, since the process speed is reduced, the time for heating by the fixing unit 47 becomes longer, and the degree of melting of the toner increases. As a result, the image quality deteriorated by reducing the toner consumption can be improved to the image quality of the normal mode. In this way, an image is formed when “toner save 2” is designated.

  When “toner save 3” is designated, various conventional toner save methods can be applied. Here, description of the contents of the processing is omitted.

  In this way, an image can be formed by the set toner saving method. In particular, as in “toner save 1” and “toner save 2”, it is possible to reduce the toner consumption, improve the image quality that has been reduced in the past, and form the image with the same image quality as in the normal mode. Conventionally, it was a trade-off between toner save and image quality degradation, but in the present invention, the image quality is maintained, and the trade-off is switched between toner save and print productivity (process speed), power (fixing temperature), and the like. Is. Note that just because the fixing temperature is increased or the process speed is lowered in the normal mode, the image quality is not improved as compared with the normal mode, and other image quality degradation such as gloss is caused. By reducing the amount of toner consumed as in the present invention, the image quality deteriorated by toner save can be improved to the image quality of the normal mode without causing much other image quality deterioration.

It is a block diagram which shows one Embodiment of this invention. It is explanatory drawing of an example of an image formation part. It is explanatory drawing of another example of an image formation part. It is a graph which shows an example of the change of the output density at the time of changing fixing temperature. It is a graph which shows an example of the change of the color reproduction area (a ^* -b ^* plane) at the time of changing fixing temperature. It is a graph which shows an example of the change of the color reproduction area (L ^* -C ^* plane) when fixing temperature is changed. It is a graph which shows an example of the relationship between a laser light quantity and output density. It is a graph which shows an example of the change of the output density at the time of changing a laser light quantity and fixing temperature. It is a graph which shows an example of the change of the color reproduction area (a ^* -b ^* plane) at the time of changing a laser light quantity and fixing temperature. It is a graph which shows an example of the change of the color reproduction area (L ^* -C ^* plane) at the time of changing a laser light quantity and fixing temperature. It is explanatory drawing of the specific example of the relationship between the toner usage-amount in each condition, and the signal value in a device independent space. It is a graph which shows an example of the relationship between development potential and output density. It is a graph which shows an example of a characteristic change at the time of changing process speed. FIG. 10 is an explanatory diagram of a specific example of a display screen for selecting toner save on a printer driver. It is a flowchart which shows an example of the operation | movement in one Embodiment of this invention. It is a flowchart (continuation) which shows an example of the operation | movement in one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Application, 3 ... Printer driver, 11 ... Drawing process part, 12 ... Toner save discrimination | determination part, 13 ... Color reproduction process part, 14 ... Tone correction part, 15 ... Halftone process part, 16 DESCRIPTION OF SYMBOLS ... Image formation control part, 17 ... Image formation part, 18 ... Processing parameter storage part, 21 ... Charging potential control part, 22 ... Exposure condition control part, 23 ... Development control part, 24 ... Fixing control part, 31 ... Toner save selection , 41, 41-1 to 4 ... photosensitive member, 42, 42-1 to 4 ... charging unit, 43, 43-1 to 4 ... laser driving unit, 44, 44-1 to 4 ... developing unit, 45 ... paper Transport path 46... Transfer roll 47. Fixing section 48. Transfer belt 51 51 Toner save selection field.

Claims (28)

  In an image forming apparatus capable of forming an image in at least a normal mode and a color material save mode, an image forming unit that adheres a color material to a recording body, a fixing unit that forms an image by melting the color material, and the color An image forming apparatus, comprising: a control unit that controls to reduce the amount of color material used in the material saving mode than in the normal mode and to increase the degree of melting of the color material by the fixing unit.   The image forming apparatus according to claim 1, wherein the control unit performs control to increase a degree of melting of the color material by increasing a fixing temperature in the fixing unit.   The image forming apparatus according to claim 1, wherein the control unit performs control so as to increase a degree of melting of the color material by increasing a heating time in the fixing unit.   The image forming apparatus according to claim 1, wherein the control unit controls the melting of the color material by the fixing unit to be performed a plurality of times to increase the degree of melting of the color material.   The image forming apparatus according to claim 1, wherein the control unit changes a degree of melting of the color material by the fixing unit according to a type of the recording body.   The image forming means irradiates light onto a pre-charged image carrier, exposes it, develops it with the color material, and transfers it to the recording body. The control means includes the image forming means. 6. The image forming apparatus according to claim 1, wherein an amount of a color material to be used is reduced by changing an exposure condition.   The image forming means irradiates light onto a pre-charged image carrier, exposes it, develops it with the color material, and transfers it to the recording body. The control means includes the image forming means. 6. The image forming apparatus according to claim 1, wherein an amount of a color material to be used is reduced by changing a charging potential of the image carrier.   The image forming means irradiates light onto a pre-charged image carrier, exposes it, develops it with the color material, and transfers it to the recording body. The control means includes the image forming means. 6. The image forming apparatus according to claim 1, wherein an amount of a color material to be used is reduced by changing a bias potential applied to the image carrier.   The image forming means irradiates light onto a pre-charged image carrier, exposes it, develops it with the color material, and transfers it to the recording body. The control means includes the image forming means. 6. The image forming apparatus according to claim 1, wherein an amount of the color material to be used is reduced by changing a density of the color material at the time of development.   10. The image forming apparatus according to claim 6, wherein the control unit changes a color material reduction amount in accordance with the type of the recording medium. 11.   Further, the image processing apparatus includes gradation characteristic correction means for correcting gradation characteristics that change by reducing the amount of color material and increasing the degree of melting of the color material, and forming an image corrected by the gradation characteristic correction means. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   And a color reproduction characteristic correction unit that corrects a color reproduction characteristic that changes by reducing the amount of the color material and increasing the melting degree of the color material, and forming an image corrected by the color reproduction characteristic correction unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   Furthermore, it has halftone characteristic correction means for correcting halftone characteristics that change by reducing the amount of color material and increasing the degree of melting of the color material, and forming an image corrected by the halftone characteristic correction means. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The control means can control the reduction of the color material by a plurality of methods, and performs control to reduce the color material according to a set method and control to increase the melting degree of the corresponding color material. The image forming apparatus according to any one of claims 1 to 13.   In an image forming method in an image forming apparatus capable of forming an image in at least the normal mode and the color material save mode, the color material amount used in the image forming means for adhering the color material to the recording medium is set in the color material save mode. An image forming method, wherein the image is formed by controlling the color material so as to increase the degree of melting of the color material by a fixing unit that forms an image by melting the color material and reducing the color material.   The image forming method according to claim 15, wherein the degree of melting of the color material is increased by increasing a fixing temperature in the fixing unit.   The image forming method according to claim 15, wherein the degree of melting of the color material is increased by lengthening the heating time in the fixing unit.   16. The image forming method according to claim 15, wherein the color material is melted by the fixing unit a plurality of times to increase the degree of melting of the color material.   The image forming method according to any one of claims 15 to 18, wherein the degree of melting of the color material by the fixing unit is changed according to the type of the recording medium.   The image forming means irradiates light onto a pre-charged image carrier, exposes it, develops it with the color material and transfers it to the recording body, and changes the exposure conditions in the image forming means. 20. The image forming method according to claim 15, wherein an amount of a color material to be used is reduced.   The image forming means exposes a precharged image carrier by irradiating light, develops it with the color material, and transfers it to the recording body. The image carrier in the image forming means 20. The image forming method according to claim 15, wherein the amount of a color material to be used is reduced by changing the charging potential of the image forming apparatus.   The image forming means exposes a precharged image carrier by irradiating light, develops it with the color material, and transfers it to the recording body. The image carrier in the image forming means 20. The image forming method according to claim 15, wherein the amount of a color material to be used is reduced by changing a bias potential applied to the image forming apparatus.   The image forming means irradiates light onto a pre-charged image carrier, exposes it, develops it with the color material, and transfers it to the recording body. 20. The image forming method according to claim 15, wherein the amount of the color material to be used is reduced by changing the density of the color material.   The image forming method according to any one of claims 20 to 23, wherein a color material reduction amount is changed in accordance with a type of the recording medium.   16. The gradation characteristic that is changed by reducing the amount of the color material and increasing the melting degree of the color material is corrected in advance by the gradation characteristic correction means, and a corrected image is formed. Item 25. The image forming method according to any one of item 24.   Furthermore, the color reproduction characteristics that change by reducing the amount of the color material and increasing the degree of melting of the color material are corrected in advance by the color reproduction characteristic correction means, and a corrected image is formed. Item 25. The image forming method according to any one of item 24.   16. A halftone characteristic that is changed by reducing the amount of color material and increasing the degree of melting of the color material is corrected in advance by a halftone characteristic correction unit, and a corrected image is formed. Item 25. The image forming method according to any one of item 24.   The color material reduction control can be performed by a plurality of methods, and the control for reducing the color material is performed according to the set method, and the control for increasing the melting degree of the corresponding color material is performed. 28. The image forming method according to claim 27.

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