JP4840657B2 - Image forming apparatus and operation method thereof - Google Patents

Description

  The present invention relates to an image forming apparatus in which the life of a photoconductor is extended, and relates to a technique for determining the presence / absence of an image to be formed for each toner color image formation and switching the operation condition based on the determination.

  As a technique for extending the life of the photoreceptor of a printing apparatus or copying apparatus, those described in Patent Document 1 and Patent Document 2 are known. Patent Document 1 describes a configuration in which an image forming apparatus having a plurality of image forming units separates a photosensitive member that is not used when forming a monochrome image from an intermediate transfer member. According to this configuration, when a monochrome image is formed, the burden on the unused photoconductor is reduced, and the life of the photoconductor can be extended. Japanese Patent Application Laid-Open No. 2004-228561 has a configuration in which a similar effect is obtained. In an image forming apparatus having a plurality of image forming units, an applied voltage to a charging roller that charges a photosensitive drum for forming a color image when a black monochrome image is formed. A configuration for lowering is described. In these prior arts, a photoconductor that is not used is selected based on whether the image to be formed is a single color image (monochrome image) or a color image.

  In addition, in the image forming apparatus, during operation, a test toner image having a predetermined pattern pattern is formed on a photoconductor, which is called setup, and is transferred to a transfer body to optically inspect the image formation state. Then, processing for adjusting various image forming conditions based on the result is performed. This setup optimizes various image forming conditions and maintains image quality. The setup is performed at a timing such as when the power is turned on, the image forming process is started, a predetermined number of sheets are output, a predetermined time has elapsed from the start of the operation, and a continuous image formation is completed. The technology related to this setup is described in, for example, Patent Document 3 and Patent Document 4.

JP 2001-242680 (paragraphs “0014”, “0105” to “0106”) JP 2001-324850 (abstract) JP-A-6-011928 (abstract) JP2003-223023 (abstract)

  By the way, even in the color image formation mode, there may be no corresponding toner color image. For example, when a color image is formed by overlapping toner images of YMCK (Yellow, Magenta, Cyan, black), there may be no corresponding toner image. However, the above-described prior art does not perform an operation for reducing the burden on the photosensitive member when forming a color image. For this reason, in the color image formation mode, the effect of extending the life of the photoreceptor cannot be obtained. This is also true for members other than the photoreceptor.

  Setup also places a burden on each part of the image forming apparatus. By the way, this setup is naturally required also in a multi-function machine having functions of a printing apparatus (printer), a FAX, and a copier, but usually the conditions for setting up each function are set to be the same. Generally, the setup conditions are set that are necessary for a printing apparatus that requires the highest quality image quality. For this reason, in the execution of the FAX function and the copying function, more than necessary setup is performed, resulting in an excessive burden on each part of the multifunction peripheral. Further, when copying a large number of sheets, setup may be executed in the middle of a copying operation. However, if this is done, the user will have to wait longer and the user may be stressed. In particular, in the case of copying that does not require so much image quality, the tendency becomes large.

  SUMMARY An advantage of some aspects of the invention is that it provides a technique capable of extending the operating life of an image forming apparatus. It is another object of the present invention to provide a technique capable of reducing the burden on the photosensitive member and extending the life of the photosensitive member and other members even in the color printing mode. Another object of the present invention is to provide a technique capable of reducing the burden on members due to setup in a multifunction machine.

  The present invention includes a latent image forming step of forming a latent image of an image image separated into a plurality of basic colors on a photoconductor, a developing step of developing the latent image and forming a toner image on the photoconductor. In an operation method of an image forming apparatus, comprising: a transfer step for transferring the toner image to a transfer target; and a fixing step for fixing the toner image transferred to the transfer target to a print medium. (1) Whether the number of pixels of the image image is 0, (2) whether the number of pixels of the image image is a predetermined value or less, 3) A determination step for determining whether or not the image image is composed only of line drawings, and a unit that constitutes the apparatus based on the determination in the determination step or in the normal image formation mode or the mode An operation mode selection step that selects any one of a plurality of types of low-load modes that reduce the load applied to the image, and according to the content selected in the operation mode selection step, the latent image forming step, the development step, An operation method of an image forming apparatus, wherein at least one of the transfer step or the fixing step is executed. The present invention also provides a latent image forming means for forming a latent image of an image image separated into a plurality of basic colors on a photoconductor, and developing for developing the latent image and forming a toner image on the photoconductor A transfer means for transferring the toner image to a transfer body; a fixing means for fixing the toner image transferred to the transfer body on a print medium; and the image image separated into a plurality of basic colors. On the other hand, (1) whether the number of pixels of the image image is 0, (2) whether the number of pixels of the image image is a predetermined value or less, and (3) the image image is only a line drawing. A plurality of kinds of determination means for determining whether or not the apparatus is configured, and a normal image forming mode or a load applied to members constituting the apparatus as compared with the mode based on the determination of the determination means One of the low-burden modes An operation mode selection means for selecting, and at least one of the latent image forming means, the developing means, the transfer means, or the fixing means is executed according to the content selected by the operation mode selection means. The image forming apparatus.

  Hereinafter, the basic principle of the present invention will be described. In general, in the normal image forming mode, various conditions are set so that an image under the strictest conditions assumed by the image forming apparatus (for example, a complex and colorful color image) can be formed with a predetermined quality. However, when forming an image with a small number of pixels or an image with only a line drawing, this normal image formation mode is over-spec, and even if each condition is relaxed, there is no problem in image formation (or the image quality is somewhat lower). Even if it falls, it is not a perceivable level and does not matter.) In other words, depending on the image, the normal image forming mode is an excessive condition, and a load is applied to each member unnecessarily.

  Therefore, in the present invention, in addition to the normal image forming mode, a low-load mode is prepared in which the load applied to members constituting the apparatus such as the photoconductor is lower than this mode. For example, in addition to the normal image formation mode in which conditions for normal image formation are set as conditions for charging the photoconductor, the charge amount on the photoconductor is lower than that and the burden on the photoconductor is reduced. Prepare a low-burden mode. Then, the low-load mode is selected based on the number of pixels of the image to be formed and / or the type of the image. As a result, the burden on members constituting the apparatus such as the photoconductor is reduced, the consumption thereof is prevented, and the operating life of the apparatus is extended. The low-load mode is realized by setting conditions such as lowering the applied voltage, lowering the operating speed of the device, lowering the charge amount, and lowering the heating temperature during image fixing. It can function and the effect of low power consumption can be obtained.

  As a member that reduces the burden by the low-load mode, the above-described photosensitive member, transfer member, member constituting the fixing device, member constituting the printing paper conveyance mechanism, and other voltages are applied, heated, or subjected to friction. A member etc. can be mentioned.

  In the image forming apparatus of the present invention, the number of pixels and / or the type of image are determined for all of the basic colors (for example, four colors of YMCK (Yellow, Magenta, Cyan, black)) that constitute a color image. . For this reason, unlike the case where only a specific basic color is the target of the low-load mode, the low-load mode is selected depending on the number of pixels of the image to be formed and / or the type of image in any basic color. Selected. As a result, even when a color image is formed, the load on each part of the apparatus can be reduced, and the life of the apparatus can be extended.

  The present invention is suitable for an image forming apparatus having a configuration in which a plurality of developing units can face one photoconductor. For example, the present invention is suitable for an image forming apparatus including one drum-type photosensitive member and a drum-type developing machine that forms toner images of YMCK basic colors on the photosensitive member. This type of image forming apparatus forms a YMCK toner image on a single photosensitive drum, which places a heavy burden on the photosensitive drum when forming a color image. Therefore, by applying the present invention, the burden on the photosensitive drum can be reduced, and the life of the photosensitive member can be extended.

  In the present invention, when the image determination unit determines that the number of pixels of the image image separated into basic colors is 0, it is desirable that the low load mode is selected in the image forming condition selection unit. According to this aspect, for example, when there is a YMCK image having zero pixels (that is, when there is no image), the setting is changed to a condition that the burden on various members is further reduced. .

  As a type of image for which the low-load mode can be selected, an image image composed only of line drawings can be cited. In this case, when the image determination unit determines that the image image separated into basic colors is composed only of line drawings, the low load mode is selected in the image forming condition selection unit. According to this aspect, for example, when a YMCK image image includes only a line drawing, the condition is changed so that the burden on members such as a photoconductor is small in the formation of the image image. The This aspect utilizes the fact that when an image is composed only of a line drawing, the image can be formed even under conditions in which the burden on members such as a photoconductor is reduced. A character string can be given as a type of image that can be selected in the low-load mode.

  In the present invention, when the image determining unit determines that the number of pixels of the image image separated into the basic colors is equal to or less than a predetermined value, the low load mode may be selected by the image forming condition selecting unit. desirable. According to this aspect, for example, when a YMCK image image has a small number of pixels, a condition for setting a lower burden on a member such as a photosensitive member is set when the image image is formed. The This aspect utilizes the fact that an image having a number of pixels equal to or less than a predetermined number can be formed even under conditions where the burden on members such as a photoconductor is reduced.

  Examples of the low-load mode in the present invention include an embodiment in which the charging potential and / or the developing bias potential of the photoconductor is smaller than that in the normal image forming mode. According to this aspect, stress applied to a member such as a photoreceptor is relieved, and deterioration and wear of the member can be suppressed. In addition, it is possible to reduce the burden on the apparatus and power supply for applying charging and developing bias, and to extend the life of these apparatuses and reduce the power consumption.

  Examples of the low-load mode in the present invention include a mode in which the photoconductor cleaner is separated from the photoconductor as compared with the normal image forming mode. According to this aspect, in the low load mode, the photoconductor cleaner does not contact the photoconductor or even if it contacts, the friction with respect to the photoconductor can be weakened, so that deterioration and wear of the photoconductor can be suppressed. Examples of the photoreceptor cleaner include a blade and a brush that scrape off toner remaining on the surface of the photoreceptor.

  Examples of the low-load mode in the present invention include a mode in which the magnitude of the electric field applied at the time of transferring the toner image from the photosensitive member to the transfer target is smaller than that in the normal image forming mode. According to this aspect, stress on the photoconductor due to the electric field applied to the photoconductor during transfer is relieved, and deterioration and wear of the photoconductor due to application of the electric field can be suppressed. The transfer target is a target to which a toner image is transferred from the photosensitive member, and examples thereof include a belt-like intermediate transfer member. Further, the transfer medium can be a recording medium (for example, printing paper) that is an object of image formation. In addition, since the burden on the configuration and power supply for applying the electric field can be reduced, the lifetime of these configurations can be extended, and the power consumption can be further reduced.

  Examples of the low-load mode in the present invention include a mode in which the developing unit is stopped at a position shifted from a position facing the photoconductor. According to this aspect, the phenomenon that the toner or carrier scattered from the developing device adheres to the photosensitive member can be suppressed, the photosensitive member can be prevented from being unnecessarily soiled, and the life of the photosensitive member can be extended.

  An example of the low-load mode in the present invention is a mode in which the driving of the developing unit is stopped. According to this aspect, it is possible to reduce a burden on the photoconductor due to development, and to suppress deterioration and wear of the photoconductor. In addition, consumption and deterioration of the developing unit can be suppressed, and further, power required for driving the developing unit can be reduced.

  Examples of the low-load mode in the present invention include conditions for reducing the peripheral speed of the developing unit as compared to the normal image forming mode. According to this aspect, it is possible to reduce a load applied to the developing unit during development, and it is possible to suppress consumption and deterioration of the developing unit. Further, toner consumption and power consumed by the developing unit can be suppressed.

  In the present invention, in the normal image forming mode, charging of the photoconductor is performed by applying a voltage in which an AC voltage and a DC voltage are superimposed, and in the low load mode, the AC voltage is reduced or zero compared to the normal image forming mode. Can be mentioned. According to this aspect, in the normal image mode, a method is used in which the AC voltage and the DC voltage are superimposed, which is advantageous for uniformly charging the photoconductor. In the low load mode, the AC voltage component is reduced (or zero) in the method of superimposing the AC voltage and the DC voltage. The application of the AC voltage has a greater degree of deterioration of the photoconductor than the application of the DC voltage. Therefore, by reducing the AC voltage component (or zero), it is possible to reduce the load applied to the photoconductor during charging. Note that, when the AC voltage component is reduced, the uniformity of charging to the photoreceptor is lowered. However, when a line drawing or character string image is formed, the influence of the nonuniformity of charging hardly appears, so that the AC voltage can be lowered as compared with the normal image forming mode.

  In the present invention, the normal image forming mode is performed by a voltage obtained by superimposing the AC voltage and the DC voltage on the developing bias applied to the photosensitive member, and the low load mode is a mode in which the AC voltage in the normal image forming mode is reduced to zero. The mode to do can be mentioned. This aspect is also based on the same principle as in the case of charging.

  In the present invention, there is provided a toner fixing means for fixing the toner by heating on the printing medium on which the toner image formed on the photosensitive member is transferred, and the low load mode determines the heating temperature and / or fixing speed of the toner fixing means. It is also possible to adopt a mode in which it is lowered as compared with the normal image forming mode. According to this aspect, since the fixing conditions are relaxed, it is possible to reduce the load applied to the fixing unit, and it is possible to suppress consumption and deterioration of the fixing unit. In addition, power consumption required for fixing an image can be suppressed. The toner image may be transferred from the photosensitive member to the transfer member and then transferred again to a print medium (for example, paper). Alternatively, the toner image may be transferred directly from the photosensitive member to the print medium. But it ’s okay.

  A plurality of these low-load mode modes can be used in combination. Also, one or more of these low-load modes can be appropriately selected based on the determination result of the number of pixels and / or the image type. Further, mode setting means for manually setting an arbitrary mode from the normal image forming mode and the low-load mode may be provided so that the mode can be set manually.

  The present invention comprises image data storage means for storing image data and image forming means for forming an image based on the image data. The image data is temporarily stored in the image data storage means, and the stored image data is stored in the image data storage means. The image formation is performed over time. According to the present invention, in forming an image that satisfies predetermined setting conditions, image formation is not immediately performed, and image data is temporarily stored in the apparatus. Then, image formation (printing) is performed based on the accumulated image data when a predetermined condition is satisfied after the accumulation. According to the present invention, for example, the accumulated image data can be collectively formed when the accumulated amount of image data and the number of accumulated jobs reach a predetermined level.

  According to the present invention, the number of cycle up / down of the image forming apparatus can be suppressed. Cycle Up / Down is a cycle from the start to the stop of the image forming operation during the image forming operation. When image formation is started, various apparatuses in the standby state start operation. At this time, various devices that start the operation are burdened, and the power consumption increases temporarily. For example, when starting the rotation of the motor, a greater burden is applied to the drive system and the power supply than during operation. In addition, the motor and heater require a larger current than when operating when starting energization. Therefore, by suppressing the number of cycle up / down of the image forming apparatus, the burden applied to each part of the apparatus can be reduced and the consumption thereof can be suppressed.

  The present invention can also be grasped as an operation method of the image forming apparatus. That is, the operation method of the image forming apparatus of the present invention includes a latent image forming step of forming a latent image of an image image separated into a plurality of basic colors on a photoconductor, developing the latent image, and toner on the photoconductor Color separation into a plurality of basic colors in an operation method of an image forming apparatus comprising a development step for forming an image, a transfer step for transferring a toner image to a transfer target, and a fixing step for fixing the toner image to a print medium Color separation image determination step for determining the number of pixels and / or image type of the image image, and based on this determination, the burden applied to the members constituting the apparatus is reduced compared to the normal image formation mode or the mode An operation mode selection step for selecting a low-load mode, and in accordance with the selected image formation conditions, a latent image formation step, a development step, a transfer step or a fixing step. Wherein at least one of the flops is performed.

  According to the operation method of the image forming apparatus, when the low-load mode is selected, processing in the low-load mode is performed in at least one of the latent image forming step, the developing step, the transfer step, and the fixing step. Is called. For example, if the latent image forming step is set to the low-load mode, the latent image is formed with a setting that lowers the charged potential of the photosensitive member. Of course, if it is not necessary to form a latent image, the photosensitive member can be set not to be charged.

  For example, if the development step is set to the low-load mode, the development step is performed with settings such as lowering the development bias potential, shifting the development unit from the position facing the photosensitive member, and stopping the development unit. If there is no image to be developed, the development process is not performed in the development step in the low burden mode. Further, if the transfer step is set to the low-load mode, the transfer from the photoconductor to the intermediate transfer body is performed, for example, with a setting that weakens the electric field applied when the toner image is transferred from the photoconductor to the intermediate transfer body. If there is no image to be developed, the toner image is not transferred in this low-load mode transfer step. Therefore, the development bias potential can be set to 0 at the timing of the primary transfer. Further, if the fixing step is set to the low-load mode, for example, it is possible to adopt a setting for slowing the sheet conveyance speed (fixing speed) at the time of fixing or lowering the temperature applied at the time of fixing.

  The determination in the operation method of the image forming apparatus of the present invention is performed in a mode for forming a color image. In this determination, (1) whether or not the number of pixels of the image image is 0, (2) the pixels of the image image It is preferable to make one or more determinations selected from whether the number is equal to or less than a predetermined value and (3) whether or not the image is composed of only line drawings.

  An image forming apparatus of the present invention is an image forming apparatus having a plurality of functions selected from a FAX function, a printing function, or a copying function, and adjusts a photosensitive member on which a toner image is formed and image forming conditions. Therefore, a test toner image forming unit that forms a test toner image on the photoconductor on a test basis and a function determination unit that determines which one of the plurality of functions is selected. The test toner image formation timing is determined based on the type.

  The appropriate formation timing of the test toner image differs depending on each function of the image forming apparatus. Further, the formation of the test toner image places a burden on each component of the image forming apparatus. Therefore, by dynamically changing the formation timing of the test toner image according to the function of the image forming apparatus, formation of useless test toner images is suppressed, thereby reducing the burden on each component of the image forming apparatus. be able to. Further, since formation of useless test toner images can be suppressed, toner consumption and power consumption can be reduced accordingly.

  The image forming apparatus of the present invention is an image forming apparatus having a plurality of functions selected from a FAX function, a printing function, or a copying function, and adjusts a photosensitive member on which a toner image is formed and image forming conditions. A test toner image forming means for forming a test toner image on the photoconductor and a function determining means for determining which of the plurality of functions is selected. The formation content of the test toner image is determined based on the type.

  According to this aspect, the formation content of the test toner image is determined based on the selection of the function. The formation content of the test toner image is a combination of the type of test toner image and the type of color. By determining the formation contents of the test toner image according to the function, it is possible to suppress the formation of the excessive test toner image in order to achieve the purpose. Power consumption can be reduced.

  The present invention also relates to an operation method of an image forming apparatus having a plurality of functions selected from a FAX function, a printing function, or a copying function, wherein a test toner is experimentally applied to a photoconductor to adjust image forming conditions. A test toner image forming step for forming an image, a function determining step for determining which of the plurality of functions is selected, and a test toner image forming timing is determined based on the selected function type And a test toner image formation timing determination step.

  The present invention also relates to an operation method of an image forming apparatus having a plurality of functions selected from a FAX function, a printing function, or a copying function, wherein a test toner is experimentally applied to a photoconductor to adjust image forming conditions. A test toner image forming step for forming an image; a function determining step for determining which of the plurality of functions is selected at the time of image formation; and formation of a test toner image based on the type of the selected function And a test toner image formation content determination step for determining the content.

  According to the present invention, the operating life of the image forming apparatus can be extended. In particular, by setting all the color-separated image images to be selected in the low-load mode, it is possible to execute a process for extending the life of the photoreceptor even in the color printing mode. Therefore, it is possible to extend the life of the photosensitive member in the image forming apparatus that performs color printing. In addition, depending on whether the FAX function, the printing function, or the copying function is selected, the execution timing and / or content of the image quality adjustment process by forming the test toner image can be changed. Thus, it is possible to reduce the load applied to each part of the apparatus associated with the formation of the test toner image while maintaining the image quality required for the test. In addition, toner consumption and power consumption associated with the formation of the test toner image can be suppressed.

1. First Embodiment (1-1: Configuration of Embodiment)
FIG. 1 is a conceptual diagram showing a configuration of an image forming apparatus using the invention. FIG. 1 shows a color printer 100 which is an example of an image forming apparatus. The color printer 100 includes a one-drum type rotary developing device 101. The rotary developing device 101 can be rotated by a driving mechanism (not shown), and includes four developing devices corresponding to YMCK basic colors.

  In this example, as a developing unit, a Y developing unit 11 that develops a yellow basic color image, an M developing unit 12 that develops a basic color image of Magenta, a C developing unit 13 that develops a basic color image of Cyan, and a basic unit of black A K developing device 14 for developing a color image is prepared. Each developing device basically has the same structure. For example, the Y developing device 11 includes a toner bottle 11a and a toner supply mechanism 11b. Each of the four toner bottles stores one of YMCK toners corresponding to the developing devices 11 to 14. Each toner supply mechanism includes a drum-like member (for example, indicated by reference numeral 11 c) for supplying toner to the photosensitive drum 103. By rotating the drum-shaped member, toner is supplied to the photosensitive drum 103. Further, the rotary developing device 101 includes a developing bias potential applying means (not shown) for applying a DC voltage as a developing bias between each toner supply mechanism and the photosensitive drum 103.

  A photosensitive drum 103 that can be rotated by a driving mechanism (not shown) is disposed in contact with the rotary developing device 101, and a static eliminator 111 is disposed in the vicinity of the photosensitive drum 103. The static elimination 111 removes the electric charge charged on the photosensitive drum 103 so that the charging by the charger 112 is performed uniformly and at a predetermined charge density. The charger 112 has a roller type made of a conductive material, and applies a voltage in which an AC voltage is superimposed on a DC voltage while being in contact with the photosensitive drum 103 to charge the surface of the photosensitive drum 103. The charge amount for the photosensitive drum 103 is controlled by controlling the value of the DC voltage.

  The photosensitive drum 103 is partially exposed to scanning light emitted from a ROS (raster optical scanner) 113, and a latent image is formed on the surface thereof. The ROS 113 is a writing exposure scanning device, and includes a laser irradiation device 113a and an optical system 113b for guiding laser light. The photosensitive drum 103 charged by the charger 112 rotates counterclockwise in FIG. 1, and at that time, the scanning light is irradiated from the ROS 113 to the photosensitive drum 103, whereby charges are captured according to the exposure pattern. As a result, a latent image is formed on the surface of the photosensitive drum 103.

  At this time, the toner supply mechanism (for example, reference numeral 11 c) of a predetermined developing device arranged in the rotary developing device 101 is controlled to a position facing the photosensitive drum 103, and any of the YMCK toners is placed on the photosensitive drum 103. The latent image is selectively supplied by being attracted by the electric field of the latent image. As a result, any toner image of YMCK is formed on the photosensitive drum 103. In this way, the latent image formed on the photosensitive drum 103 is developed.

  A cleaning blade 118 as a cleaning unit is disposed in the vicinity of the photosensitive drum 103. The cleaning blade 118 comes into contact with the surface of the photosensitive drum 103 and scrapes off the remaining toner. The toner scraped off is collected by a toner collecting unit (not shown). Further, contact / separation means (not shown) for driving the cleaning blade 118 to freely contact or separate the photosensitive drum 103 is disposed.

  An intermediate transfer member 114 is disposed in contact with the photosensitive drum 103. The intermediate transfer member 114 has a closed belt shape. Further, a primary transfer roller 115 is disposed at a position facing the photosensitive drum 103 with the intermediate transfer member 114 interposed therebetween. A bias voltage for creating a transfer electric field necessary for transferring a toner image can be applied between the photosensitive drum 103 and the primary transfer roller 115. The intermediate transfer member 114 is rotated by the driving roller 116 at a speed synchronized with the rotation of the photosensitive drum 103. At this time, the intermediate transfer member 114 is sandwiched between the photosensitive drum 103 and the primary transfer roller 115, and at that time, a bias voltage is applied between the photosensitive drum 103 and the primary transfer roller 115. Then, the transfer (primary transfer) of the toner image from the photosensitive drum 103 to the intermediate transfer member 114 is performed. For example, if the image to be formed is a color image composed of each color of YMCK, primary transfer for each color of YMCK is performed four times so that the four color images are superimposed, and a color toner image is formed on the intermediate transfer member 114. Formed.

  A cleaning roller 117 is disposed in the vicinity of the intermediate transfer member 114. The cleaning roller 117 applies a DC voltage to the intermediate transfer member 114 and positively charges the toner remaining on the intermediate transfer member 114 after the secondary transfer. The positively charged toner adheres to the photosensitive drum 103 and is recovered by the action of an electric field of DC voltage applied between the photosensitive drum 103 and the primary transfer roller 115. The toner collected on the photosensitive drum 103 is removed by the cleaning blade 118 and collected by a toner collecting unit (not shown).

  A paper cassette 123 that stores printing paper 122 is stored at the bottom of the color printer 100. The printing paper 122 is transported along the paper transport path 125 by a paper transport system typically indicated by reference numeral 124. Secondary transfer rollers 126a and 126b are arranged in the middle of the paper transport path 125. Between the secondary transfer rollers 126a and 126b, a printing sheet (not shown) that has been transported through the paper transport path 125 and the intermediate transfer body 114 are sandwiched, whereby primary transfer is performed on the surface of the intermediate transfer body 114. The toner image is further secondarily transferred to the printing paper.

  The printing paper on which the toner image is transferred moves along the paper conveyance path 125 and is conveyed between the fixing rollers 127a and 127b. The fixing roller 127b has a built-in heater, and heats the toner material constituting the toner image on the printing paper during the conveyance. By this heating, the toner is fixed, and an image is formed on the printing paper (that is, printing is performed). The printing paper on which printing has been performed is discharged from the discharge mechanism 128 onto the discharge surface 129. Reference numeral 130 denotes a paper conveyance path when double-sided printing is performed.

  FIG. 2 is a block diagram showing the configuration of the control system of the color printer 100 shown in FIG. The control means 200 includes a CPU, ROM, RAM, and various interface circuits that are not shown. The CPU supervises execution of operations described later in accordance with operation programs stored in the ROM. In addition to the above operation program, various setting conditions and data necessary for control are stored in the ROM. The RAM is used as a working area for temporarily storing various data during operation. Various interfaces have a function of exchanging signals with an apparatus controlled by the control unit 200.

  Hereinafter, an apparatus controlled by the control unit 200 will be described. The photosensitive drum driving unit 201 includes a motor for rotating the photosensitive drum 103 in FIG. 1 and a control circuit for the motor. The intermediate transfer member driving unit 202 is for controlling the cyclic movement of the intermediate transfer member 114 of FIG. 1, and includes a motor for driving the drive roller 116 and its control circuit. The charger 112 has the function described with reference to FIG. 1, and the voltage applied to the photosensitive drum 103 is controlled by the control unit 200, whereby the charge amount of the photosensitive drum 103 is adjusted. The cleaning blade contacting / separating means 203 is a driving means for performing contact and contact state of the cleaning blade 118 of FIG. 1 with the photosensitive drum 103 and separation of the cleaning blade 118 from the photosensitive drum 103. The high voltage power source 204 is a power source that generates a high voltage to be supplied to the charger 112.

  The ROS 113 is controlled by the control unit 200 and irradiates the photosensitive drum 103 with scanning light to perform optical drawing. The transfer bias control device 206 controls a bias voltage applied between the photosensitive drum 103 and the primary transfer roller 115. The Y developing unit 11, the M developing unit 12, the C developing unit 13, and the K developing unit 14 are controlled by the control unit 200 in terms of the toner supply mechanism and the developing bias potential applying unit. The developing device driving means 207 includes a motor for rotating the rotary developing device 101 and its control circuit.

  The image determination unit 208 analyzes data of an image image obtained by color-separating an image to be printed, and determines the presence or absence of the number of pixels. By determining the presence / absence of the number of pixels, it is possible to determine the presence / absence of the image (any one of YMCK). The image processing apparatus 209 receives color image data sent from a terminal or the like (color image print data sent to the color printer 100), and color-separates it into YMCK basic color image images. The color-separated image data is sent to the image determination unit 208 described above. The image processing apparatus 209 performs processing on image data such as color conversion processing from RGB to MYCK, image processing for adjusting gradation, and image processing for determining resolution. Further, the image data processed by the image processing device 209 can be stored in the image storage device 210. The image data stored in the image storage device 210 may be data at a stage before being processed by the image processing apparatus 210, or may be data at a stage when a part of the processing is completed. The image storage device 210 is constituted by a hard disk device. In addition, the color printer 100 includes an operation unit 211. The operation unit 211 is operated by the user to perform various operations and various condition settings.

(1-2: Operation of the embodiment)
FIG. 3 is a flowchart for explaining an example of the operation of the color printer 100 shown in FIGS. 1 and 2. When printing is started (step S301), image data sent from a terminal (for example, a personal computer) is taken into the image processing apparatus 209. The image data captured by the image processing apparatus 209 is color-separated into YMCK basic color image data, and each color-separated image is stored in a buffer memory (not shown). When the color-separated image is obtained, the process proceeds to step S302, and first, an image of a basic color image (Y image) of Y (Yellow) is taken into the image determination means 208. In step S303, it is determined whether or not the number of pixels of the captured Y image is zero.

  If it is determined in step S303 that the number of pixels of the Y image is not 0 (that is, if there is a Y image), the process proceeds to step S304 to set the normal image forming mode, which is a setting condition for normal printing. To do. In this example, as the normal image forming mode, the charging output of the charger 112 is set as an output during normal printing, and the transfer bias voltage applied between the photosensitive drum 103 and the primary transfer roller 115 is a value during normal printing. The cleaning blade 118 is brought into contact with the photosensitive drum 103, and further, a condition is set such that the toner supply mechanism 11b of the Y developing device 11 faces the photosensitive drum 103.

  At this time, a control signal for bringing the cleaning blade 118 into contact with the photosensitive drum 103 is output from the control means 200 of FIG. Based on this control signal, the cleaning blade contact / separation means 202 controls the position of the cleaning blade 118, and the cleaning blade 118 comes into contact with the photosensitive drum 103 and scrapes off the toner adhering to the surface of the photosensitive drum 103. Make it ready. Further, a control signal for stopping the toner supply mechanism 11 b of the Y developing device 11 at a position facing the photosensitive drum 103 is output from the control unit 200 to the developing device driving unit 207. Based on this control signal, the developing device driving means 207 rotates the rotary developing device 101 so that the toner supply mechanism 11b of the Y developing device 11 faces the photosensitive drum 103, and Y toner is applied to the photosensitive drum 103. Ready to supply.

  If it is determined in step S303 that the number of pixels of the image of the Y image is 0, the process proceeds to step S305, and a low-load mode is set in which various stresses applied to the photosensitive drum 103 are reduced as compared with normal printing. In this example, as the low-load mode, the charging output of the charger 112 is set to “no output”, the transfer bias voltage applied between the photosensitive drum 103 and the primary transfer roller 115 is set to 0V, The cleaning blade 118 is set to be separated from the photosensitive drum 103, and the toner supply mechanism 11b of the Y developing device 11 is shifted to a position not facing the photosensitive drum 103 and stopped.

  After the normal image formation mode setting processing in step S304, toner image formation processing (in this case, formation of a Y-color toner image) is performed (step S306). The toner image forming step includes the formation of the toner image on the photosensitive drum 103 and the primary transfer of the toner image to the intermediate transfer member.

  The toner image is formed on the photosensitive drum 103 as follows. First, in a state where the toner supply mechanism 11b of the Y developing device 11 is opposed to the photosensitive drum 103, the photosensitive drum 103 is rotated in the counterclockwise direction in FIG. As the photosensitive drum 103 rotates, the toner remaining on the surface of the photosensitive drum 103 is scraped off by the cleaning blade 118, and then that portion is neutralized by the static eliminator 111. The portion that has been neutralized is charged by the charger 112, and further, drawing is performed by the laser beam by the ROS 113, and a latent image (a latent image of a Y color image) is formed. The portion where the latent image is formed passes through a position facing the toner supply mechanism 11 b of the Y developing device 11 as the photosensitive drum 103 rotates. At this time, Y toner is supplied from the toner supply mechanism 11 b to the photosensitive drum 103, the toner is captured according to the latent image, and a toner image is formed on the photosensitive drum 103.

  This toner image is primarily transferred to the intermediate transfer member 114 between the photosensitive drum 103 and the primary transfer roller 115. After this transfer, the residual toner on the surface of the photosensitive drum 103 is scraped off by the cleaning blade 118. By repeating the above-described cycle, a toner image is continuously formed on the surface of the rotating photosensitive drum 103 and transferred to the intermediate transfer member 114. Then, by rotating the photosensitive drum 103 a predetermined number of times, a toner image of a predetermined basic color (Y in this case) is formed on the intermediate transfer body 114. The above is the outline of the processing performed in step S306.

  Then, after the transfer operation of the Y color toner image to the intermediate transfer body 114 is completed, it is determined whether or not all the color separation images (that is, each image of YMCK) have been formed (step S308). The determination in step S307 is also performed when the process in step S305 is performed.

  In this case, since the process related to the Y-color image has been completed, the determination in step S307 is NO, and the process returns to step S302. In step S302, the next M color image is captured, and the processing in step S303 and subsequent steps is repeated.

  By repeating the above processing, a plurality of YMCK toner images are superimposed on the intermediate transfer member 114, and a color toner image is formed on the intermediate transfer member 114. In step S308, the color toner image is secondarily transferred to the printing paper. At this time, the printing paper 122 is conveyed from the paper cassette 123 along the paper conveyance path 125 to the locations of the secondary transfer rollers 126a and 126b. The secondary transfer rollers 126a and 126b perform the secondary transfer of the toner image from the intermediate transfer body 114 to the printing paper, and the toner is fixed using the fixing rollers 127a and 127b. In this way, a color image is printed on the printing paper. The toner remaining on the surface of the intermediate transfer member 114 after the secondary transfer is positively charged by the action of the cleaning roller 117 and collected on the photosensitive drum 103.

  When an image is formed on the printing paper 122 (that is, when printing is performed), it is determined whether printing based on the print job sent from the terminal or the like is completed (step S309), and the designated print is performed. If not, the printing process ends (step S310). Otherwise, the process returns to step S302, the color separation image of the next image (the (n + 1) th image) is captured, and the same process is repeated. Then, when all the printing is completed, the determination in step S309 is YES, and the process ends (step S310).

(1-3: Advantages of the embodiment)
According to the present embodiment, when a color image is printed, if there is a missing basic color image of YMCK, the charging output of the charger 112 is set to 0 at the image formation timing. For this reason, the charging process from the charger 112 to the photosensitive drum 103 is not performed at the image formation timing. Charging from the charger 112 is performed by generating a high electric field in a minute gap between the charger 112 and the photosensitive drum 103. For this reason, the charging process causes damage to the surface of the photosensitive drum 103. Therefore, by setting the charging output of the charger 112 to 0, the life of the photosensitive drum 103 can be extended.

  Further, according to the present embodiment, when a color image is printed, if there is a missing basic color image of YMCK, it is applied between the photosensitive drum 103 and the primary transfer roller 115 at the image formation timing. The transfer bias voltage to be set is set to 0V. Since the bias voltage for transfer is also a burden on the photosensitive drum 103, by setting the value to 0, it is possible to suppress damage to the photosensitive drum.

  Further, according to the present embodiment, when there is a missing YMCK basic color image in color image printing, the cleaning blade 118 is set apart from the photosensitive drum 103 at the image formation timing. The Since the cleaning blade 118 physically contacts the surface of the photosensitive drum 103 in the cleaning state, it applies physical stress to the surface of the photosensitive drum 103. Therefore, by physically separating the cleaning blade 118 from the photosensitive drum, physical stress applied to the photosensitive drum 103 is reduced, and damage to the photosensitive drum 103 can be suppressed.

  Further, according to the present embodiment, if there is a missing color image of YMCK in color image printing, the toner supply mechanism of the corresponding developing device faces the photosensitive drum 103 at the image formation timing. It is a position that does not. By doing so, it is possible to prevent the photosensitive drum 103 from coming into contact with the toner supply mechanism at the formation timing of the basic color image, so that the stress applied to the photosensitive drum 103 can be reduced.

(1-4: Modification of Embodiment)
The values of the charging output and the transfer bias voltage of the charger 112 under the low stress condition are not limited to 0, but may be smaller than the values during normal printing. Appropriate values of these values can be obtained experimentally.

  In the low load mode, the cleaning blade 118 may not be completely separated from the photosensitive drum 103. For example, in the low-load mode, the cleaning blade 118 may come into contact with the photosensitive drum 103 lighter than during normal printing so that a certain degree of cleaning function is exhibited.

  In the low load mode, instead of retracting the toner supply mechanism of the corresponding developing device to a position not facing the photosensitive drum 103, the developing bias voltage is set during normal printing in a state where the toner supply mechanism is opposed to the photosensitive drum 103. It may be lowered by comparison or set to 0V. Further, the function of the developing device may be stopped so that no stress is applied to the photosensitive drum 103 from the rotary developing device 101.

  In the present embodiment, an example in which four colors of YMCK (Yellow, Magenta, Cyan, black) are adopted as basic colors constituting a color image has been described, but the selection of basic colors is not limited to this. In the above description, the load on the photosensitive drum 103 has been mainly described. However, the same applies to the rotary developing device 101, the charger 112, the intermediate transfer member 114, the primary transfer roller 115, and the drive. The same applies to the roller 116, the cleaning roller 117, the cleaning blade 118, the paper conveying system 124, the fixing rollers 126a and 126b, and their constituent members. Further, since the low load mode is also a low power consumption mode, the power consumption can be reduced by adopting this embodiment.

2. Second Embodiment This embodiment is an example in which three types of low-load modes are set, and the three types of low-load modes are properly used based on information on the number of pixels of the color-separated image and the type of the image.

(2-1: Configuration of Embodiment)
As the hardware configuration, the configuration shown in FIGS. 1 and 2 is used. However, an operation program for executing the procedure of FIG. 4 to be described later is adopted. In this example, the image determination unit 208 performs three types of determinations: presence / absence of the number of pixels, whether or not the number of pixels is equal to or less than a predetermined value, and whether or not the image is composed only of line drawings.

(2-2: Operation of the embodiment)
FIG. 4 is a flowchart showing an example of the operation of this embodiment. Also in this example, as in the case of the first embodiment, the following processing is sequentially executed for each of the four basic color images of YMCK.

  When printing is started (step 301), a Y-color basic image is first taken in as a color-separated image (step S402). The content of step S402 is the same as step S302 of FIG. When the color-separated image is captured, it is determined whether or not the image captured in step S402 is composed only of line drawings (step S403). If the basic color image captured in step S402 is composed only of line drawings, the process proceeds to step S406; otherwise, the process proceeds to step S404.

  In step S406, the low load mode 1 is set. In the low-load mode 1, the charging output of the charger 112, the developing bias voltage applied between the rotary developing device 101 and the photosensitive drum 103, and the transfer between the photosensitive drum 103 and the primary transfer roller 115 are applied. The transfer bias voltage to be applied is set to a small value as compared with the normal image forming conditions. This utilizes the fact that when the content to be drawn is only a line drawing, the conditions for forming a toner image on the photosensitive member and the conditions for primary transfer from the photosensitive member to the intermediate transfer member can be relaxed. By adopting the low-load mode 1, the load on the photosensitive drum 103 can be reduced. In addition, as for the specific value of each element of the low load mode 1, it is desirable to obtain an appropriate value experimentally.

  In step S404, it is determined whether or not the number of pixels of the basic color image (Y image in this case) captured in step S402 is equal to or less than a predetermined value. If the number of pixels of the basic color image captured in step S402 is equal to or smaller than the predetermined value, the process proceeds to step S405, and if not, the process proceeds to step S407.

  In step S407, the normal image forming mode is set. In the normal image forming mode, the charging output, the developing bias, the transfer bias, and the like are set under conditions that allow a predetermined image quality to be obtained regardless of the number of pixels of the basic color image and the type of image.

  In step S405, it is determined whether or not the number of pixels of the image captured in step S402 is zero. If the number of pixels of the captured image is 0, the process proceeds to step S409, and if not, the process proceeds to step S408. In step S409, the low load mode 3 is set. The setting contents of the low load mode 3 are the same as those in step S305 in FIG. When the setting in step S409 is performed, the process proceeds to step S411.

  In step S408, the setting is made to the low-load mode 2. In the low-load mode 2, the charging output of the charger 112, the developing bias voltage applied between the rotary developing device 101 and the photosensitive drum 103, and the transfer between the photosensitive drum 103 and the primary transfer roller 115 are applied. The transfer bias voltage to be applied is set to a small value as compared with the normal image forming conditions. This utilizes the fact that when the number of pixels of the image to be drawn is small, the conditions for forming the toner image on the photoconductor and the conditions for the primary transfer from the photoconductor to the intermediate transfer body can be relaxed. By adopting the low-load mode 2, the load on the photosensitive drum 103 can be reduced. In addition, as for the specific value of each element of the low load mode 2, it is desirable to obtain an appropriate value experimentally.

  After the processing of step S406, step S407, and step S408 is completed, the process proceeds to step S410 to form a toner image (Y image in this case) on the photosensitive drum 103 and to transfer the toner image to the intermediate transfer member 114. Transcription. At this time, the toner image is formed according to any one of the low-load mode 1, the low-load mode 2, and the normal image forming mode corresponding to the number of pixels of the image to be formed and the type of the image. The contents of step S410 are the same as step S306 of FIG. 3 except for the setting conditions. After step S410, the process proceeds to step S411.

  In step 411, it is determined whether or not all color separation images have been formed. If all color separation images have been formed, the process proceeds to step S412; otherwise, the process returns to the previous stage of step S402. In this description, since a Y image is formed, the determination in step S411 is NO, the process returns to step S402, the next basic color image M image is captured, and the procedure from step S403 is repeated. .

  In step S412, a secondary transfer process from the intermediate transfer body 114 to the printing paper is performed, and then it is determined whether printing based on the print job sent from the terminal or the like is completed (step S413). If the printing instructed from the terminal or the like has been completed, the process is terminated (step S414). Otherwise, the process from step S402 is repeated to form an image for the next page.

(2-3: Superiority of Embodiment)
According to the present embodiment, four types of conditions are set as appropriate based on the presence / absence of an image to be printed, the number of pixels, and the type of the image so that the burden on the photosensitive drum 103 is reduced within a range that does not hinder image formation. Is done. Therefore, in color printing, a fine and low-load mode is selected according to the image, and the life of the photosensitive drum 103 can be extended without degrading the image quality. Here, the life extension of the photosensitive drum 103 has been described. However, the effect of extending the life can be obtained with other members as well. Further, since the low load mode is also a low power consumption mode, the power consumption can be reduced by adopting this embodiment.

3. Third Embodiment In this embodiment, in the low load mode, the peripheral speed of the developing unit is set lower than that in the normal image forming mode. In the example of FIG. 1, each toner supply mechanism includes a drum-shaped member (for example, indicated by reference numeral 11 c) for supplying toner to the photosensitive drum 103. By rotating the drum-shaped member, toner is supplied to the photosensitive drum 103. In the present embodiment, the rotational speed of the drum-shaped member in the low-load mode is reduced compared to the normal image mode, and the peripheral speed of the drum-shaped member relative to the photosensitive drum 103 (relative to the surface of the photosensitive drum 103). The relative speed of the drum-like member surface on the toner supply mechanism side) is reduced. By doing so, it is possible to reduce the burden on the photosensitive drum 103 and the rotary developing device 101, and to suppress consumption of toner. Note that by reducing the peripheral speed of the developing means to the photosensitive drum 103, the amount of toner supplied to the photosensitive drum 103 is reduced. However, if a line image or an image with a small number of pixels is formed. , Can ensure a certain quality image quality.

4). Fourth Embodiment In the present embodiment, in the normal image forming mode, the photosensitive drum 103 is charged by applying a voltage obtained by superimposing an AC voltage and a DC voltage from the charger 112 to the photosensitive drum 103. In the low load mode, a condition in which the AC voltage in the normal image forming mode is reduced is employed. Note that the AC voltage in the low-load mode can be made zero.

5). Fifth Embodiment In the present embodiment, a developing bias applied between the photosensitive drum 103 and the rotary developing device 101 during development in the normal image forming mode is a voltage obtained by superimposing an AC voltage and a DC voltage. In the low load mode, a condition in which the AC voltage in the normal image forming mode is reduced is employed. Note that the AC voltage in the low-load mode can be made zero.

6). Sixth Embodiment In the present embodiment, in the low-load mode, the heating temperature applied to the paper from the fixing roller 127b shown in FIG. The speed at which the sheet is conveyed is made slower than that in the normal image forming mode. In addition, although the example which employ | adopts two conditions, low temperature and low-speed conveyance simultaneously, was shown here as conditions of a low load mode, only one of these conditions can also be employ | adopted.

7). Seventh Embodiment It is also possible to switch between a normal image forming mode and a low-load mode according to a user instruction. In addition, the user can set conditions for the low-load mode. These operations are performed by the user operating the operating means 211 shown in FIG.

8). Eighth Embodiment In this embodiment, in the case of a document or the like that does not need to be printed immediately, the print data is accumulated and printing is temporarily suspended, and the image data accumulated when a predetermined condition is satisfied is stored. Print based on this.

  In the present embodiment, the print data accumulation mode can be set in the configuration shown in FIG. In the print data storage mode, even if a print execution instruction is issued from a terminal (for example, a personal computer) connected to the color printer 100, the print data is temporarily stored in the image storage device 210 in the color printer 100, Printing is not performed. Then, printing is performed based on the accumulated image data when the number of printed image data reaches a predetermined number (for example, 100).

  Conditions that trigger the start of printing include the elapsed time from the previous printing, a predetermined time (for example, printing starts at 12:00 noon and 6 in the evening), data amount, number of jobs, manual operation, and the like. .

9. Ninth Embodiment (9-1: Configuration of Embodiment)
FIG. 5 is a conceptual diagram showing a configuration of a multifunction machine having three functions of a FAX function, a printing function, and a copying function. The multi-function device 501 has a function of printing a color image. The FAX function has a function of performing printing based on FAX image data sent via a telephone line and a function of transmitting a FAX image. The printing function is a function for performing printing based on print data prepared by a terminal (for example, a personal computer). This printing function is used as a normal printer. For printing using this printing function, printing based on image data prepared in a terminal, printing based on image data stored in an appropriate storage medium, and transmission via an appropriate line other than a telephone line Examples include printing based on image data. The copy function is a so-called copy function, and is a function for optically reading a document to be copied, converting it into electronic data, and printing the read image based on the electronic data.

  The multi-function device 501 has a tandem configuration in which images of basic colors of YMCK are performed by dedicated photoconductive drums 501 to 504. Each of the photosensitive drums 501 to 504 is irradiated with scanning light from the ROS 505 to form a latent image. The ROS 505 includes a laser oscillation device (not shown) and an optical system (not shown) for irradiating the photosensitive drums 501 to 504 with scanning light.

  The photosensitive drums 501 to 504 are supplied with corresponding color toners from the developing units 506 to 509, and toner images corresponding to the latent images are formed. The toner supplied to the developing units 506 to 509 is stored in toner bottles 51 to 54, respectively. The toner images formed on the photoconductive drums 501 to 504 are transferred onto the transfer belt 510 and are superimposed there to form a color toner image. The color toner image formed on the transfer belt 510 is secondarily transferred to the printing paper conveyed through the conveyance path 511 and further heated by the fixing unit 512 to fix the toner, thereby forming an image (printing). Is done. The printing paper on which the image is formed is discharged to a paper discharge tray 513. In the case of duplex printing, the transport path 514 is used.

  Printing paper is supplied to the paper transport path 511 from the paper cassettes 516 to 518 or the paper supply tray 519. The paper cassettes 516 to 518 are selectively used depending on the paper size and the like.

  A toner density sensor 520 that optically detects the toner density in the formed toner image is disposed in the vicinity of the transfer belt 510. The toner density sensor 520 detects the density of each color toner in the test toner image formed on the transfer belt 510.

  When performing FAX transmission, the transmission original is placed on the original placement surface 521, and the description content (display image) of the transmission original is optically read by the CCD camera 523 via the optical system 522. Then, image data is generated based on the output of the CCD camera 523, and this image data is compressed to generate FAX transmission data. This FAX transmission data is transmitted to a predetermined counterpart FAX communication apparatus. When copying, the copy original is placed on the original placement surface 521, and the image of the copy original is optically read by the CCD camera 523 via the optical system 522. Then, image data is generated based on the output of the CCD camera 523, and a copy image printing process is performed based on the image data.

  FIG. 6 is a control block diagram of the MFP 501 shown in FIG. As shown in FIG. 6, the MFP 501 includes a FAX function unit 601, a print function unit 602, a copy function unit 603, an image forming unit 604, a pattern forming unit 605, a toner density sensor 520, a setup execution determination unit 607, and a setup process determination. A control unit 608, an image forming condition control unit 609, and a controller 610 that controls the operation of each of these apparatuses and executes processing to be described later.

  A FAX function unit 601 has an optical document reading function (including a CCD camera 523 here), a function for generating electronic data (image data) of an image read there, and coding image data (data compression). And a function for decoding the received image data (data expansion) and sending it to the image forming unit 604. The print function unit 602 includes the photosensitive drums 501 to 504, the developing units 506 to 509, the transfer belt 510, and other functions necessary for forming an image in FIG. 1, and is generated by the image forming unit 604 by these functions. An image is formed (printed) based on the obtained image data.

  The copy function unit 603 has an optical document reading mechanism (here, the CCD camera 523 is included) and a function of sending electronic data of an image read there to the image forming unit 604. The FAX function unit 601 and the copy function unit 603 share a common configuration (for example, a document reading mechanism).

  The image forming unit 604 includes an ASIC that performs image conversion processing, and performs image conversion such as color conversion, gradation adjustment, resolution conversion, noise removal and screen processing for reducing the influence thereof, and conversion into data that can be interpreted by the printing function unit 602. Process. The pattern forming unit 605 has a function of generating image data of a test toner image used for setup. The setup execution determination unit 607 has a function of determining whether or not to perform setup and determining the content of the setup. The setup processing determination unit 608 determines the image quality based on the state of the test toner image (toner concentration state) read by the toner concentration sensor 520, and outputs the result to the controller 610. The image forming condition control unit 609 adjusts various setting conditions in the image forming unit 604 and the print function unit 602 based on the determination result of the setup process determination unit 608.

(9-2: Operation of the embodiment)
In the present embodiment, the multi-function device 501 executes processing related to various types of setup described below. One of the following processes may be executed, or a plurality of processes may be executed.

(Job start setup process 1)
The job start setup 1 is executed when image formation is started. In this process, it is determined whether or not to execute the setup based on the elapsed time from the previous setup execution and the changes in temperature and humidity since the previous setup.

  FIG. 7 is a flowchart showing a job start setup processing procedure. When the process is started (step S701), the setup execution determination unit 607 in FIG. 6 determines whether it is the execution timing of the job start setup process (step S702). In this example, (1) whether 4 hours have passed since the previous setup, (2) whether the temperature has changed by more than 4 ° or humidity has changed by more than 10% compared to the previous setup. These two conditions are used as criteria for determination. If at least one of the conditions is satisfied, the determination in step S702 is YES, otherwise NO.

  If at least one of the above conditions is satisfied, it is determined whether or not the image formation is a received fax image (step S703). If the received image is a fax, setup is not performed (step S704). Then, the process ends (step S707). If the image to be formed is not a FAX reception image, it is determined whether the image to be formed is a copy image (step S705). If the image to be formed is a copy image, setup is not performed (step S704), and the process is terminated (step S707). If the image to be formed is a copy image, setup is performed (step S706), and the process ends (step S707).

  In the setup in step S706, a three-tone test toner image of each color of YMCK is formed on the transfer belt 510 as shown in FIG. 8 by the function of the pattern creating unit 605 in FIG. That is, a Y-color test toner image group 801 composed of patches of three gradations (rectangular unit test toner images), and an M-color test toner image group 802 composed of patches of three gradations, respectively. C color test toner image group 803 and a K color test toner image group 804 consisting of patches of three gradations are formed. Note that the gradation is set to a pixel density of 100%, 60%, or 20%.

  The test toner image groups 801 to 804 are optically read by the toner density sensor 520, and the output is sent to the setup processing determination unit 608 via the controller 610. The setup process determination unit 608 determines the image quality (density and gradation level) of the test toner image groups 801 to 804, and based on the determination result, the image formation condition control unit 609 performs various image formation operations to be performed thereafter. Adjust the conditions. After being optically read by the toner density sensor 520, the test toner image groups 801 to 804 are not transferred onto the paper but removed from the transfer belt 510 by an appropriate cleaning unit. After adjustment by the image forming condition control unit 609, formation of a toner image 805 to be transferred onto a sheet (in this case, image formation of a print job) is performed.

  In the case of a FAX image, the demand for the stability of the highlight portion (bright portion) and halftone density is lower than that in normal printing. Therefore, in the job start setup process 1 shown in FIG. 7, priority is given to omitting the setup when forming a FAX image and suppressing the consumption of the members and the toner consumption. Also, in the case of copying (copying), if a constant image quality is maintained, there is a tendency that the printing time is as short as possible over the higher image quality, so the determination in step S702 is YES. Also, the process for omitting the setup is set to suppress the consumption of the member and the toner consumption.

  In the processing procedure shown in FIG. 7, if the setup is not performed at the time of copying, that is, if the process proceeds from step S705 to step S704, the procedure may be set so that the setup is performed after the copying process is completed.

(In-job setup process 1)
FIG. 9 is a flowchart showing the procedure of the in-job setup process 1. The in-job setup process 1 is executed at a timing during the image forming process. When the processing is started (step S721), image formation is performed based on image data of any job of FAX, copying, and normal printing (step S722). This image formation is not experimental, and is referred to as normal image formation in FIG. 9 in the sense of image formation for finally printing on paper. Next, it is determined whether or not the formed image is a FAX image (step S723). If it is a FAX image, the process proceeds to step S724, and if not, the process proceeds to step S725.

  In step S724, it is determined whether or not it is time to perform setup during the FAX image forming process. If it is that time, setup is performed (step S728), otherwise setup is not performed (step S729), and step S730. Proceed to In step S724, it is determined whether or not the total number (total number) of image formation sheets (output sheets) since the previous setup has reached a predetermined number (60 sheets in this example) or more.

  The formation of the test toner image in the setup in step S728 is performed under the same conditions as shown in FIG. 8 as shown in FIG. That is, on the transfer belt 510, a Y-color test toner image group 801 composed of patches of three gradations (rectangular unit test toner images), and a M-color test toner image group 802, 3 composed of patches of three gradations. A C-color test toner image group 803 composed of patches of each gradation and a K-color test toner image group 804 composed of patches of each of three gradations are formed. The gradation is set with pixel densities of 100%, 60%, and 20%. In FIG. 10, reference numerals 805a and 805b are formed images that are finally transferred to a sheet. The contents of the setup process using the test toner image are the same as those in the job start setup process 1.

  When the process proceeds from step S723 to step S725, it is determined whether or not a copy image is formed in step S722. If it is a copy image, the process proceeds to step S726, and if not, the process proceeds to step S727. . In step S726, it is determined whether or not it is the setup execution timing during the copy image forming process. If it is the execution timing, the setup is executed (step S728). Otherwise, the setup is not executed (step S728). Step S729), the process proceeds to Step S730.

  In step S726, it is determined whether or not the total number (total number) of image formation sheets (output sheets) since the previous setup has reached a predetermined number (60 sheets in this example) or more.

  In step S727, it is determined whether it is the execution timing of setup during the printing process (Print job). In this example, in step S727, it is determined whether or not the total number (total number) of image formation sheets (output sheets) since the previous setup has reached a predetermined number (20 sheets in this example) or more. The

  In step S730, it is determined whether or not the image forming process in step 722 is finished. If the image forming process is finished, the in-job setup process is finished (step S731). S722 and subsequent steps are executed again.

  In the example shown in FIG. 9, the determination conditions for determining the implementation of the setup are relatively loose in the FAX image forming process and the copy image forming process (when 60 sheets are formed), and relatively in the print process (Print job). (When 20 sheets are formed). In the case of a FAX image, the stability requirement for the highlight portion (bright portion) and halftone density is lower than that in the case of normal printing. Therefore, priority is given to reducing the frequency of setup during the formation of a FAX image and suppressing the consumption of members and toner consumption. Also, in the case of copying (copying), if a constant image quality is maintained, the printing time tends to be given priority over the higher image quality. The waiting time is made as short as possible. At the same time, consumption of members and toner consumption are suppressed. On the other hand, in the printing process (Print job), the frequency of setup is increased as compared with other modes, and the setting is made in pursuit of high image quality.

(Job start setup process 2)
Hereinafter, an example of the job start setup process 2 will be described. The job start setup process 2 is executed at the start of image formation. FIG. 11 is a flowchart showing the processing procedure of the job start setup process 2. When the process is started (step S741), it is determined whether it is the execution timing of the job start setup 2 (step S742). In step S742, it is determined whether 4 hours have passed since the previous setup, whether the temperature has changed by 4 ° C., or whether the humidity has changed by 10%. Note that the elapsed time of the determination condition is counted in a state where the main power supply of the apparatus is turned on (may be in a low power consumption mode).

  If the above determination in step S742 is YES, the process proceeds to step S743, and if not, the process ends (step S748). In step S743, it is determined whether the image to be formed is a FAX image. If the image is a FAX image, the process proceeds to step S744, and if not, the process proceeds to step S745. In step S744, the first setup is performed. In the first setup, the image quality determination using the test toner image is performed under the simplest determination condition in the first to third setups. FIG. 12A shows a toner image formation state in the first setup. In the first setup, test toner images 901 to 904 having one gradation (pixel density of 100%) are formed for each color of YMCK. Note that reference numeral 905 in the figure denotes an image formed by normal image formation processing after setup. The contents of the setup process using the test toner image are the same as those of the job start setup process 1 in the first to third setups.

  In step S745, it is determined whether or not the copy image is to be processed. If the image to be formed is a copy image, the second setup is performed (step S746). Otherwise, the third setup is performed (step S747). When the first to third setups are finished, the job start setup process 1 is finished (step S748).

  The determination of image quality using the test toner image of the second setup performed in step S746 is performed under simpler determination conditions than the third setup, although it is stricter than the first setup. FIG. 12B shows a toner image formation state in the second setup. In the second setup, test toner image groups 921 to 924 having two gradations (pixel density of 100% and 50%) are formed for each color of YMCK.

  The image quality determination using the test toner image of the third setup performed in step S747 is performed under the most severe determination conditions in the first to third setups. FIG. 12C shows a toner image formation state in the third setup. In the third setup, test toner image groups 931 to 934 having six gradations (pixel density of 100%, 80%, 60%, 40%, 20%, and 10%) are formed for each color of YMCK.

  In this example, in forming a FAX image that is not so demanding for image quality, the first setup is performed under the simplest conditions, and the highest priority is given to reducing the burden on each part of the apparatus associated with the setup. Further, in the formation of a copy image, the second setup is performed under moderate conditions to reduce the burden on each part of the apparatus and further reduce the time required for the setup. In normal printing, image quality is adjusted under the strictest conditions, and the image quality of the formed image is given the highest priority.

  In forming a copy image, an error diffusion screen process for diffusing a noise image and blurring it is performed on the image data in order to make dirt such as a thin pattern inconspicuous. On the other hand, in normal printing (print job), line screen processing is performed. For this reason, the stability of gradation display when a large number of sheets are continuously printed is higher when a FAX image is formed. In this example, this phenomenon is used to set up a test toner image with a smaller number of gradations when forming a FAX image than in the case of normal printing. According to the above configuration, it is possible to reduce both the burden on each part of the apparatus due to the setup, the reduction of the toner consumption, and the maintenance of the image quality obtained in each mode.

(In-job setup process 2)
FIG. 13 is a flowchart showing an outline of the processing procedure of the in-job setup process 2. The in-job setup process 2 is executed at a timing during the image forming process. When processing is started (step S751), image formation based on image data of any one of FAX, copying, and normal printing is performed (step S752). Next, it is determined whether or not the setup execution timing is determined (step S753). If the setup execution timing is reached, the process proceeds to step S754, and if not, the process proceeds to step S760. In step S753, it is determined whether or not the total number (total number) of image formation sheets (output sheets) since the previous setup has reached a predetermined number (30 sheets in this example) or more.

  In step S754, it is determined whether or not the image formed in step S752 is a fax image. If the image is a fax image, the first setup is performed (step S756). If not, the image is formed in step S752. It is determined whether or not the processed image is a copy image (step S757).

  In the first setup in step 756, image quality determination is performed using the same test toner image as the content performed in step S744 of FIG. FIG. 14A shows a toner image formation state in the first setup. In the first setup, test toner image groups 901 to 904 having one gradation (pixel density 100%) are formed for each color of YMCK. Note that reference numerals 905a and 905b in the drawing are normal images formed at timings before and after setup.

  If the determination in step S754 is no, the process proceeds to step 757 to determine whether or not the process is a copy image. If the image to be formed is a copy image, the second setup is performed (step S758). Otherwise, the third setup is performed (step S759). When the first to third setups are completed, it is determined whether there is any remaining normal image formation processing (the job of the image formation processing is finished) or not (step S760), and there is no normal image to be formed. If there is a normal image to be formed, the processing from step S752 is repeated.

  FIG. 14B shows a toner image formation state in the second setup. In the second setup, test toner image groups 921 to 924 having two gradations (pixel density of 100% and 50%) are formed for each color of YMCK. FIG. 14C shows a toner image formation state in the third setup. In the third setup, test toner image groups 931 to 934 having six gradations (pixel density of 100%, 80%, 60%, 40%, 20%, and 10%) are formed for each color of YMCK.

  According to the processing procedure of FIG. 13, the same advantage as that of the processing procedure shown in FIG. 11 can be obtained. That is, in forming a FAX image that does not require a high degree of demand for image quality, the first setup is performed under the simplest conditions, and the burden on each part of the apparatus accompanying the setup is given the highest priority. Further, in the formation of a copy image, the second setup is performed under intermediate conditions to balance the burden on each part of the apparatus and the image quality of the formed image, and further reduce the time required for the setup. . In normal printing, image quality is adjusted under the strictest conditions, and the image quality of the formed image is given the highest priority.

10. Tenth Embodiment For example, in the determination of step S753 in FIG. 13, it is determined whether or not the image forming process has ended (whether or not the job has ended), and when the image forming job ends, step S754 and the subsequent steps. To execute setup. In this case, the determination in step S760 is not performed.

11. 11. Eleventh embodiment (setting of setup execution conditions by the user)
The user can also set whether or not to set up or how often. For example, in the MFP shown in FIGS. 5 and 6, a user interface screen such as a liquid crystal display for presenting various information to the user is arranged. This user interface screen is a touch panel type, and various operations can be performed when the user directly touches.

  FIG. 15A is a display example on the user interface screen. FIG. 15A shows a display example in the case of manually setting the setup execution frequency at each timing. In FIG. 15A, job start is an item that determines whether or not to perform setup when an image forming job occurs. “During job” is an item for determining whether or not to perform setup at a predetermined timing while a plurality of images are being formed. The job end is an item that determines whether or not to perform setup when the image forming job is completed. Note that the setup contents set on the setting screen shown in FIG. 15A are set separately or predetermined ones are used.

  In the setting screen of FIG. 15A, OFF indicates a setting for not performing setup. In addition, “High execution frequency” indicates the condition setting for performing the setup with the highest frequency, “Medium execution frequency” indicates the condition setting for setting up with the medium frequency, and “Low execution frequency” indicates the setup with the lowest frequency. The condition setting for performing is shown. The user can arbitrarily set each of these setting conditions using the touch panel function described above.

  Here, the use of “high execution frequency”, “medium execution frequency”, and “low execution frequency” in the job start item is as follows. For example, in the setting of “high execution frequency” in the job start item, the setup is executed so that the setup is executed when the cumulative number of image formations from the previous setup is 10 or more. Is set so that the setup is executed when the cumulative number of images formed since the previous setup is 20 or more, and the setting of “Infrequently executed” is set from the previous setup. The setup is set to be executed when the cumulative number of image formations is 30 or more.

  The use of setting items in the items in the job is as follows. For example, in the setting of “high execution frequency” in the item in the job, the setup is performed so that the setup is executed when the number of continuous image forming sheets reaches five, and in the setting of “execution frequency”, continuous The setup is set to be executed when the number of image forming sheets reaches 10, and the setting of “low execution frequency” is set so that the setup is executed when the number of continuous image forming sheets reaches 20. Is set.

  Also, the usage of setting items in the job end item is as follows. For example, in the setting of “high execution frequency” in the job end item, when the number of images formed by the job is 10 or more, the setup is executed after the image forming process is completed. In the setting of “execution frequency”, when the number of images formed by the job is 20 or more, the setup is executed after the image forming process is completed. In addition, in the setting of “low execution frequency”, when the number of images formed in the job is 30 or more, the setup is executed so that the setup is executed after the image forming process is completed.

  Next, an example of a setting screen on which the setup contents can be set will be described. FIG. 15B shows a setting screen on which settings for determining the contents of setup can be made. OFF shown in FIG. 15B is a setting that does not perform setup. The “setup time length” is a setting when the setup time is the longest. When “setup time length” is selected, a test toner image for setup is provided with fine gradation settings as shown in FIG. However, since many test toner images are formed, the time required for setup becomes longer.

  When “During Setup Time” is selected on the setting screen shown in FIG. 15B, the setup time is set to a medium level. When “medium” is selected, a test toner image for setup is provided with a medium gradation setting as shown in FIG. 12B, for example. However, compared with the case where the smallest gradation setting is selected (in this case, the case of FIG. 12A), the time required for setup becomes longer.

  When “short setup time” is selected on the setting screen shown in FIG. 15B, the time required for setup is set to the shortest time. When “short setup time” is selected, the test toner image for setup has the simplest floor as shown in FIG. 12 (A), as compared with the case of FIG. 12 (B) or (C). It is provided with the key setting. In this case, the time required for setup can be minimized.

12 Other Embodiments In the above examples, the example in which the setup is performed using the timing for forming the normal image is shown. However, the test toner image is formed in the interimage between the images to be formed and the setup is performed. You can also.

  In the above example, the example of changing the setup execution timing and execution contents based on the functions of FAX, copying, and printing has been described. However, the setup execution timing and execution are further determined depending on whether the function is in monochrome mode or color mode. It can also be configured to determine the contents. In this case, the monochrome mode is set so that the setup frequency and / or execution time is longer than the color mode.

  Further, the frequency and / or contents of the setup can be determined based on the operating tendency of the apparatus. For example, unit time (for example, one day), average number of output sheets per job, volume of formed image and amount of toner used, ratio of monochrome image formation to color image formation, use ratio for each process speed, FAX / copy / The setup implementation frequency and / or implementation content may be changed as appropriate based on the usage ratio of each printing mode, the average time from power ON to the start of image formation, and the like.

  The present invention can be used in an image forming apparatus such as a color printer, a FAX, a color copying machine, or a complex machine of these.

It is a conceptual diagram which shows the structure of the color printer using invention. FIG. 2 is a block diagram illustrating a configuration of a control system of the color printer illustrated in FIG. 1. It is a flowchart which shows the operation | movement procedure of embodiment. It is a flowchart which shows the operation | movement procedure of embodiment. 1 is a conceptual diagram illustrating a configuration of a multifunction machine using the invention. It is a control block diagram which shows the structure of the control system of the multifunctional device using invention. It is a flowchart which shows the operation | movement procedure of embodiment. FIG. 6 is a conceptual diagram illustrating a formation state of a test toner image. It is a flowchart which shows the operation | movement procedure of embodiment. FIG. 6 is a conceptual diagram illustrating a formation state of a test toner image. It is a flowchart which shows the operation | movement procedure of embodiment. FIG. 6 is a conceptual diagram illustrating a formation state of a test toner image. It is a flowchart which shows the operation | movement procedure of embodiment. FIG. 6 is a conceptual diagram illustrating a formation state of a test toner image. It is a screen display figure which shows the setting screen which sets a setup condition.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Color printer, 101 ... Rotary developing device, 103 ... Photosensitive drum, 111 ... Electric discharger, 112 ... Charger, 114 ... Intermediate transfer body, 115 ... Primary transfer roller, 118 ... Cleaning blade.

Claims (2)

A latent image forming step of forming a latent image of an image image separated into a plurality of basic colors on a photoconductor;
A developing step of developing the latent image and forming a toner image on the photoreceptor;
A transfer step of transferring the toner image to a transfer medium;
A fixing step of fixing the toner image transferred to the transfer medium onto a print medium;
For the image image separated into a plurality of basic colors,
(1) whether or not the number of pixels of the image is 0;
(2) whether or not the number of pixels of the image is less than or equal to a predetermined value;
(3) Whether or not the image is composed only of line drawings,
A determination step for determining
An operation mode selection step for selecting one of a normal image forming mode or a plurality of types of low-load modes in which a load applied to members constituting the apparatus is reduced compared to the mode based on the determination in the determination step; With
An operation method of an image forming apparatus, wherein at least one of the latent image forming step, the developing step, the transferring step, or the fixing step is executed according to the content selected in the operation mode selecting step .   Latent image forming means for forming a latent image of an image image separated into a plurality of basic colors on a photoconductor;
  Developing means for developing the latent image and forming a toner image on the photoreceptor;
  Transfer means for transferring the toner image to a transfer target;
  Fixing means for fixing the toner image transferred to the transfer medium onto a print medium;
  For the image image separated into a plurality of basic colors,
(1) whether or not the number of pixels of the image is 0;
(2) whether or not the number of pixels of the image is less than or equal to a predetermined value;
(3) Whether or not the image is composed only of line drawings,
  Determining means for determining
  An operation mode selection unit that selects one of a normal image forming mode or a plurality of types of low-load modes in which a load applied to members constituting the apparatus is reduced as compared with the mode based on the determination of the determination unit;
  With
  The image forming apparatus according to claim 1, wherein at least one of the latent image forming unit, the developing unit, the transfer unit, and the fixing unit is executed according to the content selected by the operation mode selecting unit.

Images