JP4424055B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming method, and more particularly to a developer supply technology to a developing device in an image forming apparatus using an electrophotographic system such as a multifunction peripheral such as a copying machine, a printer, and a facsimile machine.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copiers, printers, and facsimiles using an electrophotographic method are widely known. Such an image forming apparatus includes a developing device and a toner supply device, and supplies toner from the toner supply device to the developing device during image formation.

  On the other hand, in recent years, downsizing of image forming apparatuses has progressed, and developing devices in the apparatus have also been downsized. When the developing device is downsized, the amount of toner that can be stored in the developing device also decreases, so the amount of toner that can be supplied per unit time also decreases, and if high-area coverage images are printed continuously, the toner supply cannot catch up. There was a problem.

  Therefore, in the technique described in Patent Document 1, when the accumulated value of the insufficient supply amount of toner exceeds a predetermined upper limit value, printing is interrupted to provide an idle cycle, and during the idle cycle, By supplying the toner, it is possible to prevent the toner supply from being caught up.

In addition, since the technology described in Patent Document 1 uses a two-component developer composed of toner and carrier, the toner and carrier can be agitated by an idling cycle, and image quality defects such as image streaks and unevenness can be prevented. Can do.
JP 2002-372845 A

  However, when the technique described in Patent Document 1 is applied to an image forming apparatus having a plurality of print speeds, the developing device decelerates according to the print speed at a print speed lower than normal, but the toner supply device is at a constant speed. Since the toner supply amount is relatively increased, the chance of the toner shortage supply amount reaching the predetermined upper limit value is greatly reduced than usual, and the stirring operation of the toner and the carrier is also reduced. There is a problem that image quality deterioration occurs due to a decrease in the stirring operation.

  On the other hand, even if the toner supply itself is in time, the developing device is downsized, so the ability to impart charge to the toner is also reduced, and when continuously printing images with high area coverage, In other words, the toner has a lower charge imparting ability, and as a result, the toner density is lowered and image quality defects such as streaks and unevenness are likely to occur.

  The present invention has been made to solve the above problems, and can maintain an appropriate amount of developer in the developing device and can prevent image quality deterioration due to a decrease in the charge amount of the developer or the like. An object is to provide an apparatus and an image forming method.

In order to achieve the above object, an invention according to claim 1 is an image forming apparatus comprising: a developing device that develops a latent image using a developer; and a supply device that supplies the developer to the developing device. In the image forming cycle for forming an image on a recording medium, image density information for each image forming cycle is obtained, an image density management value obtained by subtracting a predetermined value from the image density information is calculated, and An integrating means for calculating an integrated value obtained by integrating the image density management values; and when the integration result of the integrating means is equal to or greater than a predetermined threshold, the developer in the developing device is agitated and the developer by the supplying device Control means for controlling the developing device and the supply device so as to perform an idling cycle for supplying the image, and the integrating means adds a predetermined value when the image density management value is a negative value. New value As the image density management value, when the new image density management value is positive, the new image density management value is set to 0, and when the new image density management value is negative, the new image density management value is accumulated. It is characterized that you accumulated in value.

  According to the first aspect of the present invention, the image density information for each cycle is acquired by the integrating means during the image forming cycle, and an image density management value obtained by subtracting a predetermined value from the image density information is calculated. The Then, an integrated value obtained by integrating the calculated image density management value is calculated.

  In the control unit, when the integration result of the integration unit is equal to or greater than a predetermined threshold, the developer in the developing device is stirred and the idling cycle in which the developer is supplied by the supply device is performed. The feeding device is controlled. That is, by this, the developer is agitated and supplied, and it is possible to suppress a decrease in the charge amount of the developer by the agitation.

  As described above, since the shift to the idling cycle is performed by accumulating the image density management value corresponding to the area coverage during image formation instead of the insufficient supply amount of the developer as in the technique described in Patent Document 1 described above. When the image formation speed is slower than the normal speed, even if the supply of the developer is in time, it is possible to cope with a decrease in the charge amount of the developer in the developing device due to the continuous image formation of the high area coverage image. It can be stabilized. Further, by shifting to the idling cycle, when the developer is insufficient, the developer is also supplied, so that the developer can be maintained in an appropriate amount.

Therefore, the developer amount in the developing device can be kept at an appropriate amount, and image quality deterioration due to a decrease in the charge amount of the developer can be prevented.
Further , when the image density management value is negative, when the new image density management value is positive, the integrating means uses a value obtained by adding a predetermined value to the image density management value as a new image density management value. When the new image density management value is set to 0 and the new image density management value is negative, the new image density management value is added to the integrated value, and the image density management value is set appropriately. When forming the middle area coverage image, the integrated value is less subtracted, and when the high area coverage image is formed again later, it becomes easier to shift to the idling cycle, and the image quality can be further stabilized.

As the threshold value, as in the invention according to claim 2, having a plurality of values, the control unit, continuous image formation number of cycles to reach ambient environment mode at the time of image formation, and idle cycle The threshold value may be selected according to at least one of the above.

Further, the idling cycle time for performing the idling cycle has a plurality of set values (idling cycle times) as in the invention according to claim 3 , and the control means controls the ambient environment, the mode at the time of image formation, and The set value may be selected according to at least one of the number of continuous image formations until the idling cycle is reached.

Further, according to the present invention, as in the invention described in claim 4 , the developing device includes a rotary developing device having a plurality of developing devices, and a plurality of toner images are formed by the plurality of developing devices to form a full color image. The present invention can be applied to an image forming apparatus to be formed. That is, by applying the present invention to a so-called four-cycle color image forming apparatus, an idling cycle can be carried out immediately after completion of development in a developing apparatus that requires an idling cycle, so that the developing apparatus is newly rotated later. This eliminates the need for processing time.

At this time, as in the fifth aspect of the present invention, when at least one developing unit of the developing device, the control unit determines that the current image formation is performed when the integration result of the integration unit exceeds a predetermined threshold value. When the cycle is completed, the developing device and the supply device may be controlled so as to shift to the idling cycle for the corresponding developing device, and the control means, as in the invention according to claim 6 , In at least one developing unit of the apparatus, when the integration result of the integrating unit becomes equal to or greater than a predetermined threshold value, development is performed so as to shift to the idling cycle for all the developing units when the current image forming cycle is completed. You may make it control an apparatus and a supply apparatus.

According to the fifth aspect of the present invention, when the development of the current image forming cycle is completed, the process shifts to the idling cycle, so that the output time of the current page can be shortened. Further, as in the invention described in claim 6 , by performing the idling cycle for other developing devices that have not reached the threshold value, all the developing devices in the developing device are refreshed, and the image quality is further improved. It can be stabilized.

The invention according to claim 7 is an image forming method of an image forming apparatus comprising: a developing device that develops a latent image using a developer; and a supply device that supplies the developer to the developing device. In the image forming cycle for forming an image on the top, the image density information for each image forming cycle is acquired, and an image density management value obtained by subtracting a predetermined value from the image density information is calculated, and the image density management is performed. An integration step for calculating an integrated value obtained by integrating the values; and when the integration result of the integration step is equal to or greater than a predetermined threshold, the developer in the developing device is agitated and the developer is supplied by the supply device. to perform idle cycles performed, the control step of controlling the developing device and the supply device, only contains the integration step, wherein when the image density control value is a negative value, a value obtained by adding a predetermined value The As the new image density management value, when the new image density management value is positive, the new image density management value is set to 0, and when the new image density management value is negative, the new image density management value is set. The integrated value is integrated .

According to the seventh aspect of the present invention, in the integrating step, image density information for each cycle is acquired during the image forming cycle, and an image density management value obtained by subtracting a predetermined value from the image density information is calculated. The Then, an integrated value obtained by integrating the calculated image density management value is calculated.

  Further, in the control step, when the integration result of the integration step is equal to or greater than a predetermined threshold, the developer in the developing device is stirred, and the developing device and the idling cycle for supplying the developer by the supply device are performed. The feeding device is controlled. That is, by this, the developer is agitated and supplied, and it is possible to suppress a decrease in the charge amount of the developer by the agitation.

  As described above, since the shift to the idling cycle is performed by accumulating the image density management value corresponding to the area coverage during image formation instead of the insufficient supply amount of the developer as in the technique described in Patent Document 1 described above. When the image formation speed is slower than the normal speed, even if the supply of the developer is in time, it is possible to cope with a decrease in the charge amount of the developer in the developing device due to the continuous image formation of the high area coverage image. It can be stabilized. Further, by shifting to the idling cycle, when the developer is insufficient, the developer is also supplied, so that the developer can be maintained in an appropriate amount.

Therefore, the developer amount in the developing device can be kept at an appropriate amount, and image quality deterioration due to a decrease in the charge amount of the developer can be prevented.
In addition , when the image density management value is negative, when the image density management value is negative, a value obtained by adding a predetermined value to the image density management value is set as a new image density management value. When the new image density management value is set to 0 and the new image density management value is negative, the new image density management value is added to the integrated value, and the image density management value is set appropriately. When the middle area coverage image is formed, the integrated value is less subtracted, and when the high area coverage image is formed again later, it becomes easier to shift to the idling cycle, and the image quality can be further stabilized.

Further, the threshold value has a plurality of values as in the invention described in claim 8 , and in the control step, the surrounding environment, the mode at the time of image formation, and the number of continuous image formation cycles until the idling cycle is reached. The threshold value may be selected according to at least one of the above.

Further, the idling cycle time for performing the idling cycle has a plurality of set values (idling cycle time) as in the invention according to claim 9 , and in a control step, the ambient environment, the mode at the time of image formation, The set value may be selected according to at least one of the number of continuous image formations until the idling cycle is reached.

The method of the present invention, as in the invention according to claim 1 0, the developing apparatus consists of a rotary developing apparatus having a plurality of developing devices, by forming a plurality of toner images by a plurality of developing units The present invention can be applied to an image forming apparatus that forms a full-color image. That is, by applying the present invention to a so-called four-cycle color image forming apparatus, an idling cycle can be carried out immediately after completion of development in a developing apparatus that requires an idling cycle, so that the developing apparatus is newly rotated later. This eliminates the need for processing time.

At this time, in the control step, as in the invention of claim 1 1, in at least one developing unit of the developing device, when the accumulation result of the accumulating means is equal to or greater than the predetermined threshold value, the current image after completing the formation cycle may be controlled developing device and a supply device to transition to the idle cycles for developing device applicable, as in the invention according to claim 1 2, in the control step In at least one developing device of the developing devices, when the integration result of the integrating means becomes equal to or greater than a predetermined threshold value, when the current image forming cycle is finished, all the developing devices are shifted to the idling cycle. Further, the developing device and the supply device may be controlled.

By like the invention of claim 1 1, since the development of the current image forming cycle proceeds to idle cycle upon completion, it is possible to shorten the output time of the current page. It is preferable as defined in claim 1 2, that also performs the idle cycle for the other developing devices does not reach the threshold value, will be developing device all in the developing device is refreshed, more quality Can be stabilized.

  As described above, according to the present invention, it is possible to maintain an appropriate amount of developer in the developing device and to prevent image quality deterioration due to a decrease in the charge amount of the developer.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, the present invention is applied to a four-cycle full-color printer.

  FIG. 1 is a diagram showing a schematic configuration of a four-cycle full-color printer as an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, a photosensitive drum 2 is rotatably disposed in the full color printer main body 1 at an upper right portion slightly from the center. As this photosensitive drum 2, for example, a drum made of a conductive cylinder having a diameter of about 47 mm whose surface is coated with a photosensitive layer made of OPC or the like is used. It is rotationally driven at a process speed of about 150 mm / sec. The surface of the photosensitive drum 2 is charged to a predetermined potential by a charging roll 3 disposed almost directly below the photosensitive drum 2, and then ROS 4 disposed at a position just below the photosensitive drum 2. Image exposure with a laser beam (LB) is performed by (Raster Output Scanner), and an electrostatic latent image corresponding to image information is formed. The electrostatic latent image formed on the photosensitive drum 2 passes through the developing devices 5Y, 5M, 5C, and 5K of yellow (Y), magenta (M), cyan (C), and black (K) in the circumferential direction. The toner is developed by a rotary developing device 5 arranged along the toner image to form a toner image of a predetermined color.

  At this time, charging, exposure and development processes are repeated a predetermined number of times on the surface of the photosensitive drum 2 in accordance with the color of the image to be formed. In the rotary developing device 5, the corresponding color developing devices 5 </ b> Y, 5 </ b> M, 5 </ b> C, and 5 </ b> K move to a developing position facing the photosensitive drum 2. For example, when a full-color image is formed, the charging, exposure, and development processes are performed on the surface of the photosensitive drum 2 in yellow (Y), magenta (M), cyan (C), and black (K) colors. The toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is sequentially formed on the surface of the photosensitive drum 2. . The number of rotations of the photosensitive drum 2 when the toner image is formed varies depending on the size of the image. For example, in the case of A4 size, one image can be obtained by rotating the photosensitive drum 2 three times. It is formed. That is, a toner image corresponding to each color of yellow (Y), magenta (N / 1), cyan (C), and black (K) is displayed on the surface of the photosensitive drum 2 every time the photosensitive drum 2 rotates three times. Is formed. Hereinafter, this cycle of forming one image (for example, for one page) is referred to as an image forming cycle.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drum 2 are intermediately provided on the outer periphery of the photosensitive drum 2 as an intermediate transfer member. At the primary transfer position around which the transfer belt 6 is wound, the primary transfer is performed by the primary transfer roll 7 while being superimposed on the intermediate transfer belt 6. The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred in multiple onto the intermediate transfer belt 6 are recorded on the recording paper 9 fed at a predetermined timing. Secondary transfer is collectively performed by the secondary transfer roll 8. The recording paper 9 is fed by a pickup roll 11 from a paper feed cassette 10 disposed at the lower part of the full-color printer main body 1, and is fed in a state where it is rolled one by one by a feed roll 12 and a retard roll 13. The roller 14 is conveyed to the secondary transfer position of the intermediate transfer belt 6 in synchronization with the toner image transferred onto the intermediate transfer belt 6.

  The intermediate transfer belt 6 is stretched by a plurality of rolls, and is driven as the photosensitive drum 2 rotates, for example, so as to circulate at a predetermined process speed (about 150 mm / sec). The intermediate transfer belt 6 intermediately transfers a wrap-in roll 15 that specifies the wrap position of the intermediate transfer belt 6 on the upstream side in the rotational direction of the photosensitive drum 2 and a toner image formed on the photosensitive drum 2. The primary transfer roll 7 to be transferred onto the belt 6, the wrap-out roll 16 for specifying the wrap position of the intermediate transfer belt 6 on the downstream side of the wrap position, and the secondary transfer roll 8 are in contact with each other via the intermediate transfer belt 6. The backup roll 17, the first cleaning backup roll 19 facing the cleaning device 18 of the intermediate transfer belt 6, and the second cleaning backup roll 20 are stretched with a predetermined tension.

  The full-color printer according to the embodiment of the present invention is miniaturized as much as possible as a whole, but the rotary developing device 5 occupies a large space of the full-color printer main body 1. Therefore, the full-color printer main body 1 is designed to improve the maintainability of the intermediate transfer belt 6 and the rotary developing device 5 while achieving downsizing of the device. Specifically, the intermediate transfer belt 6 includes an image forming unit 21 including the photosensitive drum 2 and the charging roll 3, and an upper cover 22 as a replacement cover for the full-color printer main body 1. By opening, the entire image forming unit 21 is configured to be detachable from the full-color printer main body 1. A position sensor 23 composed of a reflective photosensor for detecting a toner patch formed on the intermediate transfer belt 6 is disposed on the intermediate transfer belt 6.

  More specifically, the image forming unit 21 includes the photosensitive drum 2, the charging roll 3, the intermediate transfer belt 6, and a plurality of rolls 7, 15 to 17, 19, 20 that stretch the intermediate transfer belt 6. The cleaning device 18 for the intermediate transfer belt 6 and the cleaning device 34 for the photosensitive drum 2 are integrally mounted. The image forming unit 21 can be taken out from the printer body 1 by holding and holding a handle (not shown) provided on the upper portion of the image forming unit 21 by hand.

  On the other hand, the recording paper 9 onto which the toner image has been transferred from the intermediate transfer belt 6 is conveyed to a fixing device 27, and the toner image is fixed on the recording paper 9 by heat and pressure by the fixing device 27. In this case, the paper is discharged as it is onto a discharge tray 29 provided at the top of the printer main body 1 by the discharge roll 28.

  As shown in FIG. 2, the rotary developing device 5 of the full-color printer according to this embodiment includes yellow (Y), magenta (M), cyan (C), and black (K) along the counterclockwise direction. The five developing units 5Y, 5M, 5C, and 5K are mounted along the circumferential direction, and yellow (Y), magenta (M), Five developer cartridges 45Y, 45M, 45C, and 45K of cyan (C) and black (K) are mounted along the circumferential direction.

  Inside each of the developing devices 5Y, 5M, 5C, and 5K, a part of the developing devices 5Y, 5M, 5C, and 5K is disposed so as to be exposed to the outer periphery, and is perpendicular to the paper surface. Developing rolls 48Y, 48M, 48C, and 48K that are long in the direction, and two spiral augers 49 and 50 that extend in parallel to the developing rolls 48Y, 48M, 48C, and 48K are arranged. In the developing units 5Y, 5M, 5C, and 5K, when the developing rolls 48Y, 48M, 48C, and 48K rotate, one auger 49 uses the developer contained in the developing units 5Y, 5M, 5C, and 5K as the paper surface. Transport while stirring in one vertical direction. On the other hand, the other auger 50 conveys the developer in a direction opposite to the conveying direction of the auger 50 while stirring the developer, and supplies the developer evenly to the developing rolls 48Y, 48M, 48C, and 48K. .

  More specifically, each developer cartridge 45Y, 45M, 45C, 45K is provided with a spiral agitator 51 (see FIG. 2) that is rotatably arranged. By the rotation of the agitator 51, development is performed. The developer is supplied to the auger 49 by conveying the developer in the agent cartridges 45Y, 45M, 45C, and 45K to the auger 49 while stirring. Then, the augers 49 and 50 are conveyed while stirring to supply the developer evenly to the developing rolls 48Y, 48M, 48C, and 48K.

  Next, a control system for supplying the developer to the developing devices 5Y, 5M, 5C, and 5K of the rotary developing device 5 will be described.

  FIG. 3 is a block diagram showing the configuration of a control system for supplying the developer from the developer cartridges 45Y, 45M, 45C, 45K to the developing devices 5Y, 5M, 5C, 5K of the rotary developing device 5.

  The control unit 60 of the full-color printer according to the present embodiment has an image density that is a value obtained by subtracting a predetermined value (Base_Pix) from image density information that is a numerical value corresponding to area coverage for each cycle during an image forming cycle. The control value (Dif_Pix) is integrated, and when this integrated value (Total_Dif_Pix) exceeds the predetermined threshold (Limit_HAC), the process shifts from the image formation cycle to the idling cycle where no image is formed, and the developer agitation supply process is performed. To control. During the idling cycle, the control unit 60 controls the drive of the drive motor 62 to drive the developer cartridges 45Y, 45M, 45C, 45K agitator 51 and the augers 49, 50 of the developing units 5Y, 5M, 5C, 5K. As a result, the developer is supplied while stirring the developer.

  The control system for supplying the developer is formed around the control unit 60, and image density information (Pix_per_page) corresponding to each color from the ROS 4 is input to the control unit 60. Note that image density information may be input to the control unit 60 from the main control unit 64 that controls the entire full-color printer. As for the image density information, the light emission amount of the ROS 4 may be monitored, and the monitored light emission amount may be input to the control unit 60.

  The controller 60 includes an agitator 51 for supplying the developer to the auger 49 while stirring the developer cartridges 45Y, 45M, 45C, and 45K corresponding to each color, and a developer roll 48Y, 48M, 48C, and 48K. A drive motor 62 is connected to drive the augers 49 and 50 for supplying them with stirring through gears (not shown). The drive motor 62 is driven according to a developer supply stirring signal output from the control unit 60. Is controlled. Thus, the developer is supplied from the developer cartridges 45Y, 45M, 45C, 45K to the developing rolls 48Y, 48M, 48C, 48K while stirring.

  Further, a feed stop signal and a feed start signal of the recording paper 9 are output from the control unit 60 to the main control unit 62, and the main control unit 64 stops the feed or feed from the control unit 60. In response to the start signal, the drive of the recording paper conveyance system 66 is controlled to control the stop or start of feeding of the recording paper.

  In addition, a non-volatile memory 68 and a work memory 70 are provided in the control unit 60, and various setting values are stored in the non-volatile memory 68. For example, as various setting values, setting values for controlling the idling cycle (for example, the above-mentioned Base_Pix, threshold Limit_HAC, etc.) are stored. The work memory 70 is mainly used for performing calculations for performing the idling cycle, and stores, for example, calculation of values such as Dif_Pix and Total_Dif_Pix described above, calculation results, and the like. A plurality of threshold values may be stored. At this time, the plurality of threshold values are set values (threshold values) corresponding to, for example, at least one of the ambient temperature and humidity of the full-color printer, the print mode at the time of image formation, and the number of continuous image formation cycles until shifting to the idling cycle. ), It is possible to achieve both high image quality stabilization and high productivity. Further, the non-volatile memory 68 also stores the cycle time at the idling cycle. At this time, the idling cycle time is, for example, the idling cycle time corresponding to at least one of the ambient temperature and humidity of the full-color printer, the print mode at the time of image formation, and the number of continuous image forming cycles until the idling cycle is started. By separately setting in advance, it is possible to achieve both high image quality stabilization and high productivity.

Next, an example of a developer agitation supply process performed by the control unit 60 during image formation by the full color printer configured as described above will be described.
[First Embodiment]
FIG. 4 is a flowchart showing the first embodiment of the flow of the developer agitation supply process performed by the control unit 60. Note that the processing of FIG. 4 is performed for each color, and if any one of the colors is subjected to the idling cycle, it is assumed that the idling cycle is performed for the other colors, but the idling cycle is performed separately for each color. You may make it perform a cycle. Basically, the above-described four-cycle image forming apparatus is applied. However, since the following processing can be applied to a general tandem image forming apparatus, the tandem image forming apparatus is applied. Will be explained at the same time.

  First, in step 100, image density information (Pix_per_page) is input from the ROS 4 to the control unit 60, and the process proceeds to step 102.

  In step 102, a predetermined value (Base_Pix) stored in advance in the nonvolatile memory 68 is subtracted from the image density information (Pix_per_page) input to the control unit 60 to calculate an image density management value (Dif_Pix).

  In step 104, the integrated value (Total_Dif_Pix = Total_Dif_Pix + Dif_Pix) of the image density management value (Dif_Pix) calculated in step 102 is calculated, and the process proceeds to step 106.

  In Step 106, it is determined whether or not the calculated integrated value (Total_Dif_Pix) is negative. If the determination is affirmative, the process proceeds to Step 108, where the integrated value (Total_Dif_Pix) is replaced with 0, 110. If the determination in step 106 is negative, the process proceeds to step 110 as it is.

  In step 110, it is determined whether or not the integrated value (Total_Dif_Pix) is equal to or greater than the threshold value (Limit_HAC) stored in the nonvolatile memory 68. If the determination is negative, the process returns to step 100 and the above processing is repeated. When the determination at step 110 is affirmed, the routine proceeds to step 112.

  In step 112, a feed stop signal is output to the main control unit 64 in the tandem image forming apparatus, and a rotation postponement signal to the next developing unit is output in the four-cycle image forming apparatus. The drive of the recording paper conveyance system 66 or the rotary developing device 5 is stopped by the unit 64, and the recording paper feed or the rotation of the developing device is stopped. In other words, the image forming operation is stopped when the currently performed image forming cycle is completed.

  Subsequently, in step 114, the idling cycle process is performed. That is, the drive motor 62 is driven by the control of the control unit 60, and the agitator 51 and the augers 49 and 50 are driven via a gear (not shown). As a result, the developer is stirred and the developer is supplied to the developing device.

  As described above, in the four-cycle type image forming apparatus, it is possible to shift to the idling cycle immediately after the end of the image forming cycle, so that it is not necessary to newly rotate the rotary developing device later, and the processing time is shortened. can do. In the present embodiment in the tandem image forming apparatus, when any one of the developing devices 5Y, 5M, 5C, and 5K shifts to the idling cycle, the idling cycle is also performed for the other developing devices 5Y, 5M, 5C, and 5K. As a result, the developers in all the developing devices 5Y, 5M, 5C, and 5K can be refreshed, and the image quality can be stabilized.

  Next, in step 116, the integrated value (Total_Dif_Pix) is reset (Total_Dif_Pix = 0), and the process proceeds to step 118, where a feed start signal or a developer rotation start signal is output to the main control unit 64, and a series of steps are performed. The developer agitation supply process is terminated. That is, the main control unit 64 resumes driving of the recording paper conveyance system 66 or the rotary developing device 5, and the recording paper is fed or the developing device is rotated to restart the image forming cycle.

  For example, FIGS. 5A and 5B show an example of the case where the predetermined value (Base_Pix) is 50 and the threshold value (Limit_HAC) is 100 in the developer agitation supply process of the first embodiment.

  In FIG. 5A, first, the image density information (Pix_per_page) of the first page is 100, a predetermined value is subtracted from the image density information (Dif_Pix = Pix_per_page-Base_Pix), and the image density management value (Dif_Pix) is 50. Thus, the integrated value (Total_Dif_Pix) is 50. Then, the image density information (Pix_per_page) of the second page is 100 as in the first page, a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) is 50, and the integrated value (Total_Dif_Pix) is Since the threshold value becomes 100, the idling cycle of step 114 is performed, and similarly, the third and fourth pages are performed.

  In the case of FIG. 5B, first, the image density information (Pix_per_page) of the first page is 90, a predetermined value is subtracted from the image density information (Dif_Pix = Pix_per_page-Base_Pix), and the image density management value (Dif_Pix) is 40, and the integrated value (Total_Dif_Pix) is 40. The image density information (Pix_per_page) of the second page is 80, a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) is 30, and the integrated value (Total_Dif_Pix) is 70. The image density information (Pix_per_page) of the third page is 40, a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) is −10, and the integrated value (Total_Dif_Pix) is 60. The image density information (Pix_per_page) of the fourth page is 10, a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) is −40, and the integrated value (Total_Dif_Pix) is 20. The image density information (Pix_per_page) of the fifth page is 10, like the fourth page, and a predetermined value is subtracted from the image density information, and the image density management value (Dif_Pix) becomes −40, and the integrated value (Total_Dif_Pix) However, the determination in step 106 is affirmed, and the integrated value (Total_Dif_Pix) is replaced with 0. That is, it is possible to prevent the integrated value from becoming a negative value and difficult to shift to the idling cycle.

  Further, the image density information (Pix_per_page) of the sixth page is 60, a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) becomes 10, the integrated value (Total_Dif_Pix) becomes 10, and Step 110 The accumulated value is accumulated until the determination of is positive.

As described above, in this embodiment, the developer can be stirred and supplied by shifting to the idling cycle by accumulating the image density management value (Dif_Pix) corresponding to the area coverage during image formation. Even when the speed is low, a stable developer can be supplied, and it is possible to cope with a decrease in the charge amount in the developing device when images with high area coverage are continuously formed.

Accordingly, the toner amount in the developing device can be maintained at an appropriate amount, and image quality deterioration due to a decrease in the toner charge amount can be prevented.
[Second Embodiment]
Next, a second embodiment of the developer agitation supply process performed by the control unit 60 will be described. FIG. 6 is a flowchart showing a second embodiment of the flow of the developer agitation supply process performed by the control unit 60. Note that the processing in FIG. 6 is performed for each color as in the first embodiment, and when the idle cycle processing is performed for any one color, the idle cycle is also performed for the other colors. However, the idling cycle may be performed separately for each color. Basically, the above-described four-cycle image forming apparatus is applied. However, since the following processing can be applied to a general tandem image forming apparatus, the tandem image forming apparatus is applied. Will be explained at the same time.

  First, in step 200, image density information (Pix_per_page) is input from the ROS 4 to the control unit 60, and the process proceeds to step 202.

  In step 202, an image density management value (Dif_Pix) is calculated by subtracting a predetermined value (Base_Pix) stored in advance in the nonvolatile memory 68 from the image density information (Pix_per_page) input to the control unit 60.

  In step 204, it is determined whether or not the image density management value (Dif_Pix) calculated in step 202 is positive. If the determination is affirmative, the process proceeds to step 206.

  In step 206, the integrated value (Total_Dif_Pix = Total_Dif_Pix + Dif_Pix) of the image density management value (Dif_Pix) calculated in step 202 is calculated, and the process proceeds to step 208.

  In step 208, it is determined whether or not the calculated integrated value (Total_Dif_Pix) is equal to or greater than the threshold value (Limit_HAC) stored in the nonvolatile memory 68. If the determination is negative, the process returns to step 200 and the above-described processing is performed. Is repeated, and when step 208 is determined, the routine proceeds to step 210.

  On the other hand, if the determination in step 204 is negative, the process proceeds to step 218, and the image density management value (Dif_Pix) is not immediately replaced with 0 as in the first embodiment (Dif_Pix = Dif_Pix + Under_Base).

  Subsequently, in step 220, it is determined again whether or not the image density management value (Dif_Pix) is positive. If the determination is affirmative, the process proceeds to step 221 where the image density management value (Dif_Pix) is set to 0. Returning to step 200, the above-described processing is repeated. That is, when the new image density management value (Dif_Pix) is positive, the image density management value (Dif_Pix) is set to 0 and the process returns to step 200 without being integrated. If the determination in step 220 is negative, the process proceeds to step 222.

  In step 222, an integrated value (Total_Dif_Pix = Total_Dif_Pix + Dif_Pix) of the image density management value (Dif_Pix) is calculated, and the process proceeds to step 224.

  In step 224, it is determined whether or not the calculated integrated value (Total_Dif_Pix) is negative. If the determination is affirmative, the process proceeds to step 226, where the integrated value (Total_Dif_Pix) is replaced with 0. Returning to 200, the above-described processing is repeated. If the determination in step 224 is negative, the process returns to step 200 and the above process is repeated.

  If the determination in step 208 is affirmative, the process proceeds to step 210 to perform the idling cycle as in the first embodiment, and the feed to the main control unit 64 is performed in the tandem image forming apparatus. A stop signal is output, and in the four-cycle image forming apparatus, a rotation postponement signal is output to the next developing device, and the main control unit 64 stops driving the recording paper transport system 66 or the rotary developing device 5. The recording paper feed or the rotation of the developing device is stopped, and the routine proceeds to step 212. In other words, the image forming operation is stopped when the currently performed image forming cycle is completed.

  In step 212, the idling cycle process is performed. That is, the drive motor 62 is driven by the control of the control unit 60, and the agitator 51 and the augers 49 and 50 are driven via a gear (not shown). As a result, the developer is stirred and the developer is supplied to each developing device.

  As described above, in the four-cycle type image forming apparatus, it is possible to shift to the idling cycle immediately after the end of the image forming cycle, so that it is not necessary to newly rotate the rotary developing device later, and the processing time is shortened. can do. In the present embodiment in the tandem image forming apparatus, when any one of the developing devices 5Y, 5M, 5C, and 5K shifts to the idling cycle, the idling cycle is also performed for the other developing devices 5Y, 5M, 5C, and 5K. As a result, the developers in all the developing devices 5Y, 5M, 5C, and 5K can be refreshed, and the image quality can be stabilized.

  In step 214, the integrated value (Total_Dif_Pix) is reset (Total_Dif_Pix = 0), and the process proceeds to step 216, where a feed start signal or a developer rotation start signal is output to the main control unit 64, and a series of developments are performed. The agent agitation supply process is terminated. That is, the main control unit 64 resumes driving of the recording paper conveyance system 66 or the rotary developing device 5, and the recording paper is fed or the developing device is rotated to restart the image forming cycle.

  For example, in the developer agitation supply process of the second embodiment, an example in which the predetermined value (Base_Pix) is 50, the threshold value (Limit_HAC) is 100, and the raised value (Under_Base) is 25 is shown in FIGS. ).

  In FIG. 7A, as in the first embodiment, first, the image density information (Pix_per_page) of the first page is 100, a predetermined value is subtracted from the image density information (Dif_Pix = Pix_per_page-Base_Pix), and the image The density management value (Dif_Pix) is 50, and the integrated value (Total_Dif_Pix) is 50. Then, the image density information (Pix_per_page) of the second page is 100 as in the first page, a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) is 50, and the integrated value (Total_Dif_Pix) is Since it becomes 100 and becomes the threshold value, the idling cycle of step 214 is performed, and similarly, the third page and the fourth page are performed.

  In the case of FIG. 7B, first, the image density information (Pix_per_page) of the first page is 90, a predetermined value is subtracted from the image density information (Dif_Pix = Pix_per_page-Base_Pix), and the image density management value (Dif_Pix) is 40, and the integrated value (Total_Dif_Pix) is 40. The image density information (Pix_per_page) of the second page is 80, a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) is 30, and the integrated value (Total_Dif_Pix) is 70. The image density information (Pix_per_page) of the third page is 40, and a predetermined value is subtracted from the image density information (Dif_Pix = Pix_per_page-Base_Pix), and the image density management value (Dif_Pix) becomes −10. The determination of 204 is denied, the image density management value (Dif_Pix) is raised (Dif_Pix = Dif_Pix + Under_Base) to 15 and the new image density management value (Dif_Pix) is positive, so the determination of step 220 is affirmed. Since the new image density management value (Dif_Pix) is 0, the integrated value (Total_Dif_Pix) is 70. That is, the decrease in the minus direction of the integrated value (Total_Dif_Pix) is smaller than that in the first embodiment, and it becomes easier to shift to the idling cycle, and the image quality can be stabilized.

  Further, the image density information (Pix_per_page) of the fourth page is 10, and a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) becomes −15, the determination in step 220 is denied, and step 222 is performed. And the integrated value (Total_Dif_Pix) becomes 55. The image density information (Pix_per_page) of the fifth page is 10, the predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) becomes −15, the determination in step 220 is affirmed, and the routine proceeds to step 222. Thus, the integrated value (Total_Dif_Pix) becomes 40. The image density information (Pix_per_page) of the sixth page is 60, a predetermined value is subtracted from the image density information, the image density management value (Dif_Pix) is 10, the integrated value (Total_Dif_Pix) is 65, and the determination in step 210 The accumulated value is accumulated until is affirmed.

  As described above, in this embodiment, as in the first embodiment, the process shifts to the idling cycle by accumulating the image density management value (Dif_Pix) corresponding to the area coverage during image formation, and the developer is stirred and supplied. Therefore, even when the print spade is slow, the developer can be supplied stably, and the charge amount in the developer can be reduced when images with high area coverage are continuously formed. It becomes possible to respond.

  Accordingly, the toner amount in the developing device can be maintained at an appropriate amount, and image quality deterioration due to a decrease in the toner charge amount can be prevented.

In the second embodiment, if the raised value (Under_Base) of the image density management value (Dif_Pix) is appropriately set, the integrated value (Total_Dif_Pix) is not easily subtracted when an image of the middle area coverage is formed. Thus, when an image with a high area coverage is formed later, it is possible to easily enter the idling cycle, and the image quality can be further stabilized as compared with the first embodiment.
[Third Embodiment]
Next, a third embodiment of the developer agitation supply process performed by the control unit 60 will be described. FIG. 8 is a flowchart showing a third embodiment of the flow of the developer agitation supply process performed by the control unit 60.

  In addition, 3rd Embodiment is a modification of 1st Embodiment, and the process which selects a threshold value (Limit_HAC) with respect to 1st Embodiment was added, and the same code | symbol is attached | subjected about the same process. I will explain. In this embodiment, the print mode has three modes of a normal mode, a high gloss mode, and a super high gloss mode, and a threshold value is selected according to these modes.

  The print mode may be set in the main control unit 64 via a user interface or the like, or may be set for each page.

  First, in step 100, image density information (Pix_per_page) is input from the ROS 4 to the control unit 60, and the process proceeds to step 102.

  In step 102, the image density management value (Dif_Pix) is calculated by subtracting a predetermined value (Base_Pix) stored in advance in the nonvolatile memory 68 from the image dense path information (Pix_per_page) input to the control unit 60.

  In step 104, the integrated value (Total_Dif_Pix = Total_Dif_Pix + Dif_Pix) of the image density management value (Dif_Pix) calculated in step 102 is calculated, and the process proceeds to step 106.

  In Step 106, it is determined whether or not the calculated integrated value (Total_Dif_Pix) is negative. If the determination is affirmative, the process proceeds to Step 108, where the integrated value (Total_Dif_Pix) is replaced with 0, 109. If the determination at step 106 is negative, the process proceeds to step 109 as it is.

  In step 109, a threshold (Limit_HAC) selection process is performed. Details of the selection process will be described later.

  Subsequently, in step 110, it is determined whether or not the integrated value (Total_Dif_Pix) is equal to or greater than the threshold value (Limit_HAC) selected in the Limit_HAC selection process in step 109. If the determination is negative, the process returns to step 100 and described above. When the determination in step 110 is affirmed, the process proceeds to step 112.

  In step 112, a feed stop signal is output to the main control unit 64 in the tandem image forming apparatus, and a rotation postponement signal to the next developing unit is output in the four-cycle image forming apparatus. The drive of the recording paper conveyance system 66 or the rotary developing device 5 is stopped by the section 64, and the recording paper feed or the rotation of the developing device is stopped. In other words, the image forming operation is stopped when the currently performed image forming cycle is completed.

  Subsequently, in step 114, the idling cycle process is performed. That is, the drive motor 62 is driven by the control of the control unit 60, and the agitator 51 and the augers 49 and 50 are driven via a gear (not shown). As a result, the developer is stirred and the developer is supplied to each developing device.

  As described above, in the four-cycle type image forming apparatus, it is possible to shift to the idling cycle immediately after the end of the image forming cycle, so that it is not necessary to newly rotate the rotary developing device later, and the processing time is shortened. can do. In the present embodiment in the tandem image forming apparatus, when any one of the developing devices 5Y, 5M, 5C, and 5K shifts to the idling cycle, the idling cycle is also performed for the other developing devices 5Y, 5M, 5C, and 5K. As a result, the developers in all the developing devices 5Y, 5M, 5C, and 5K can be refreshed, and the image quality can be stabilized.

  Next, in step 116, the integrated value (Total_Dif_Pix) is reset (Total_Dif_Pix = 0), and the process proceeds to step 118, where a feed start signal or a developer rotation start signal is output to the main control unit 64, and a series of steps are performed. The developer agitation supply process is terminated. That is, the main control unit 64 resumes driving of the recording paper conveyance system 66 or the rotary developing device 5, and the recording paper is fed or the developing device is rotated to restart the image forming cycle.

  As described above, in this embodiment, as in the first embodiment, the process shifts to the idling cycle by accumulating the image density management value (Dif_Pix) corresponding to the area coverage during image formation, and the developer is stirred and supplied. Therefore, even when the print spade is slow, the developer can be supplied stably, and the charge amount in the developer can be reduced when images with high area coverage are continuously formed. It becomes possible to respond.

  Accordingly, the toner amount in the developing device can be maintained at an appropriate amount, and image quality deterioration due to a decrease in the toner charge amount can be prevented.

  Here, the threshold value (Limit_HAC) selection process will be described. FIG. 9 is a flowchart illustrating an example of a flow of threshold (Limit_HAC) selection processing.

  When the process proceeds to the threshold value (Limit_HAC) selection process, first, in step 300, it is determined whether or not the super high gloss mode is set. If the determination is affirmative, the process proceeds to step 302 and the threshold value (Limit_HAC) is set to 70. Then, the process proceeds to step 110 described above.

  If the determination in step 300 is negative, the process proceeds to step 304 and it is determined whether or not the mode is the high gloss mode. If the determination is affirmative, the process proceeds to step 306 and the threshold (Limit_HAC) Is set to 80, and the process proceeds to step 110 described above.

  Here, when the determination in step 304 is negative, since it is neither the super high gloss mode nor the high gloss mode, the process proceeds to step 308 as the normal mode, the threshold (Limit_HAC) is set to 100, and the above-described step 110.

  Thus, in this embodiment, since the threshold (Limit_HAC) is selected according to the print mode, the timing for shifting to the idling cycle can be changed according to the print mode, and appropriate developer agitation and supply can be performed. It can be performed.

  In this embodiment, the threshold (Limit_HAC) selection process is added to the first embodiment. However, the threshold (Limit_HAC) selection process may be added to the second embodiment. .

  In this embodiment, the threshold value (Limit_HAC) is selected according to the print mode. However, the present invention is not limited to this, and the threshold value is limited to at least one of the ambient temperature, humidity, print mode, and number of image forming cycles. The threshold may be selected.

  In the above-described embodiment, the present invention is applied to a full-color printer including the rotary developing device 5. However, the present invention is not limited to this. For example, a photosensitive drum and a developing device are provided for each color. The present invention may be applied to a general tandem type full-color printer.

1 is a diagram showing a schematic configuration of a four-cycle full-color printer as an image forming apparatus according to an embodiment of the present invention. It is a figure which shows schematic structure of a rotary developing device. FIG. 4 is a block diagram illustrating a configuration of a control system that supplies developer to each lower organ of the rotary developing device. 4 is a flowchart illustrating a first embodiment of a flow of developer agitation supply processing performed by a control unit. 10 is a table showing an example when a predetermined value (Base_Pix) is 50 and a threshold (Limit_HAC) is 100 in the developer agitation supply process of the first embodiment of the present invention. 10 is a flowchart illustrating a second embodiment of a proposed developer agitation supply process performed by a control unit. 10 is a table showing an example when a predetermined value (Base_Pix) is 50, a threshold value (Limit_HAC) is 100, and a raised value (Under_Base) is 25 in the developer agitation supply process of the second embodiment of the present invention. 10 is a flowchart illustrating a third embodiment of a developer agitation supply process performed by a control unit. It is a flowchart which shows an example of the flow of a threshold value (Limit_HAC) selection process.

Explanation of symbols

4 ROS
49, 50 Auger 51 Agitator 60 Control unit 62 Drive motor 64 Main control unit 66 Recording paper transport system 68 Non-volatile memory 70 Work memory

Claims (12)

An image forming apparatus comprising: a developing device that develops a latent image using a developer; and a supply device that supplies the developer to the developing device,
During an image forming cycle for forming an image on a recording medium, image density information for each image forming cycle is acquired, an image density management value obtained by subtracting a predetermined value from the image density information is calculated, and the image An integration means for calculating an integrated value obtained by integrating the density management value;
When the integration result of the integration means is equal to or greater than a predetermined threshold, the developer in the developing device is agitated and the idling cycle for supplying the developer by the supply device is performed, and the developing device and the Control means for controlling the supply device;
Equipped with a,
When the image density management value is a negative value, the integrating means uses a value obtained by adding a predetermined value as a new image density management value. If the new image density management value is positive, a new image density the control value set to 0, when the new image density control value is negative, the image forming apparatus characterized that you integrating the new image density control value to the integrated value. The threshold value has a plurality of values, and the control unit selects the threshold value according to at least one of an ambient environment, a mode at the time of image formation, and the number of continuous image formation cycles until the idling cycle is reached. The image forming apparatus according to claim 1. The idling cycle time for performing the idling cycle has a plurality of set values, and the control means has at least one of an ambient environment, an image forming mode, and the number of continuous image forming cycles until the idling cycle is reached. The image forming apparatus according to claim 1 , wherein the setting value is selected in response . 4. The developing device according to claim 1, wherein the developing device comprises a rotary developing device having a plurality of developing devices, and a full color image is formed by forming a plurality of toner images by the plurality of developing devices. whether the image forming apparatus according to (1). The control unit is configured to develop the corresponding developing unit at the time when the current image forming cycle is completed when the integration result of the integration unit exceeds a predetermined threshold in at least one of the developing devices of the developing device. The image forming apparatus according to claim 4 , wherein the developing device and the supply device are controlled so as to shift to the idling cycle with respect to the image forming apparatus. The control means is configured so that, in at least one of the developing devices of the developing device, when the integration result of the integration means is equal to or greater than a predetermined threshold value , The image forming apparatus according to claim 4 , wherein the developing device and the supply device are controlled so as to shift to the idling cycle . An image forming method of an image forming apparatus comprising: a developing device that develops a latent image using a developer; and a supply device that supplies the developer to the developing device.
During an image forming cycle for forming an image on a recording medium, image density information for each image forming cycle is acquired, an image density management value obtained by subtracting a predetermined value from the image density information is calculated, and the image An integration step for calculating an integrated value obtained by integrating the density management value;
When the integration result of the integration step is equal to or greater than a predetermined threshold value, the developer in the developing device is agitated, and the idling cycle in which the developer is supplied by the supply device is performed, and the developing device and the A control step for controlling the supply device;
Including
In the integration step, when the image density management value is a negative value, a value obtained by adding a predetermined value is used as a new image density management value. If the new image density management value is positive, a new image density is obtained. An image forming method comprising: adding a new image density management value to the integrated value when the management value is 0 and the new image density management value is negative. The threshold value has a plurality of values, and the control step selects the threshold value according to at least one of an ambient environment, a mode at the time of image formation, and the number of continuous image formation cycles until the idling cycle is reached. The image forming method according to claim 7 . The idling cycle time for performing the idling cycle has a plurality of set values, and at the control step, the idling cycle time is at least one of an ambient environment, an image forming mode, and the number of continuous image forming cycles until the idling cycle is reached. 8. The image forming method according to claim 8, wherein the set value is selected according to the method. A full-color image forming apparatus in which the developing device includes a rotary developing device having a plurality of developing devices, and the image forming device forms a plurality of toner images by the developing devices of the rotary developing device. The image forming method according to claim 7, wherein the image forming method comprises: In the control step, when at least one of the developing devices of the developing device, when the integration result of the integration step is equal to or greater than a predetermined threshold, the corresponding development is completed when the current image forming cycle is completed. The image forming method according to claim 10 , wherein the developing device and the supply device are controlled such that the developing device shifts to the idling cycle . At the time of completion of the current image forming cycle when the integration result of the integration step is equal to or greater than a predetermined threshold in at least one of the developing devices of the developing device in the control step, The image forming method according to claim 10 , wherein the developing device and the supply device are controlled so as to shift to the idling cycle .

Images