JP2007057929A - Image forming apparatus and toner supply method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of exerting stabilization control even when printing, for example, in a monochrome mode has been continuing, capable of obtaining a stable image even when the monochrome mode is switched at any time to a color mode, which is different in toner consumption from the monochrome mode, and capable of ensuring stable image quality without causing insufficient supply of color toner due to the stabilization control, and to provide a toner supply method for the image forming apparatus. <P>SOLUTION: The image forming apparatus that exerts the stabilization control includes: a toner forcible supply determination means for determining, based on the history of the stabilization control whether toner forcible supply needs to be carried out or not, and a toner forcible supply means for carrying out the toner forcible supply, based on the result of the determination after the stabilization control is carried out. The toner supply method for the image forming apparatus is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a toner replenishing method thereof. More specifically, an image forming apparatus that controls the stabilization of an image to be formed by forming a toner pattern image on an image carrier and detecting the toner pattern image or the transferred toner pattern image, and its toner supply Regarding the method.

  One of the mainstream methods for forming full-color images is to use four photosensitive drums along the recording medium conveyance belt or intermediate transfer belt (hereinafter referred to as “transfer belt”) conveyance direction or circumferential direction. The toner images of each color of magenta, cyan, yellow, and black (hereinafter, these reproduced colors are respectively expressed as M, C, Y, and K) are formed on the surface of each photosensitive drum. There is a so-called tandem method in which a full-color image is formed by sequentially transferring the formed toner images onto the transfer belt or the recording medium.

  Of course, the tandem image forming apparatus can form not only full-color images but also monochrome images. Conventionally, when forming a monochrome image, an image is not formed on the surface of the three photosensitive drums M, C, and Y, but an image is formed only on the surface of the K photosensitive drum. Therefore, in the monochrome image formation, neither development nor transfer of M, C, and Y color toners is performed.

  In general, in an image forming apparatus, an appropriate image can always be formed in response to changes in the in-machine environment (temperature, humidity, etc.). In the tandem type image forming apparatus, image formation for each color is possible. For the purpose of correcting misalignment, a pattern image is formed with toner on the surface of the photosensitive drum or on the transfer belt, and the pattern image is detected using a photoelectric sensor or the like. So-called image stabilization control for determining various image forming conditions is performed.

  The image stabilization control is performed by detecting the pattern image formed on the surface of the photosensitive drum, and after the pattern image formed on the surface of the photosensitive drum is transferred to the transfer belt, the transferred pattern image is detected. There is something to do. As a control that cannot be performed unless the pattern image is transferred to the transfer belt, for example, by detecting the position of the pattern image, a shift in the image forming position generated between the four photosensitive drums is detected, and the four images are detected according to the detection result. There is a so-called registration correction for correcting the image forming position between the photosensitive drums.

  On the other hand, control to adjust the developing bias voltage and the exposure amount on the surface of the photosensitive drum based on the detection result of the toner adhesion amount of the pattern image to obtain an appropriate image density at all times (hereinafter referred to as “image density stabilization”). Control ”can also be performed by detecting the toner adhesion amount of the pattern image formed on the surface of the photosensitive drum. Generally, the toner adhesion amount of the pattern image transferred to the transfer belt is detected. It is possible to perform control with higher accuracy. This is because when the toner adhesion amount of the pattern image formed on the surface of the photosensitive drum is detected, a change in transfer efficiency when transferring to the transfer belt cannot be reflected in the control.

  In general, in image formation, as the image formation continues, the toner in the developer is consumed, and the toner density decreases. Since the toner density of the developer greatly affects the image density, toner is automatically replenished with development. In controlling the image density stabilization, how to control the toner supply is also an important issue.

  In order to keep the toner density constant, a technique for calculating a change in toner density within a predetermined time and setting a condition for controlling the toner replenishment amount using a sensor for detecting the toner density in the developing device has been proposed. (For example, refer to Patent Document 1).

  However, controlling the toner density alone is not sufficient to stabilize the image density. Image density is affected by changes in various environments, durability conditions, and process conditions. In order to cope with these, as described above, the toner adhesion amount of the pattern image is detected, the toner concentration as a control target is changed in addition to the exposure amount and the bias condition, and the toner replenishment amount control is performed to achieve the target toner concentration. A technique for performing the above has also been proposed (see, for example, Patent Document 2).

  In such image density stabilization control for controlling toner replenishment, a difference in toner consumption depending on image conditions must be taken into consideration. That is, depending on the image to be formed, there are cases where the toner consumption is high or low. A case where the influence is particularly great is the difference between the color image and the monochrome image described above. In forming a color image, toner of each color is consumed. In forming a monochrome image, only monochrome toner is consumed.

  Even when a monochrome image is being formed, since it is not known when the color image formation is switched to, a technology has been proposed in which image stabilization control is also performed for a color image and the stabilization control is not required at the time of switching. (For example, refer to Patent Document 3).

  However, in the image density stabilization control for controlling the toner supply as described above, it is meaningless unless it can be reflected in the toner supply operation. Even when a monochrome image is being formed, stabilization control regarding a color image is possible, but color toner is consumed by the stabilization operation itself. On the other hand, what is actually being performed is monochrome image formation in which only monochrome toner is consumed, and only the monochrome toner is subjected to supply control during that time. During the monochrome image formation, the color toner is not replenished. Therefore, the decrease in the toner density consumed by the stabilization operation remains untreated.

When switching to color image formation in such a situation, there is a possibility that the image density is insufficient and a good image quality cannot be obtained.
Japanese Patent Laid-Open No. 5-100573 JP-A-5-158348 JP 2001-5344 A

  As described above, when monochrome image formation is continued, image stabilization control can be performed during that time, but color toner is consumed by the operation itself. On the other hand, since the monochrome image formation continues, the color toner is not replenished, and therefore the replenishment amount control is not effective.

  As a result, there may be a case where good image quality cannot be obtained when switching from monochrome image formation to color image.

  The object of the present invention is to solve the above-mentioned problems and determine the necessity of forced toner replenishment according to the state of toner consumption during execution of stabilization control regardless of the print mode, and forcibly replenish toner if necessary. Thus, it is an object to provide an image forming apparatus and a toner replenishing method thereof that can obtain a stable image quality even when switching to a print mode in which toner consumption is different.

  In order to solve the above problems, the present invention has the following features.

  (1) In an image forming apparatus that controls the stabilization of an image to be formed by forming a toner pattern image on an image carrier and detecting the toner pattern image or the transferred toner pattern image. Toner forcible replenishment determination means for determining whether or not to forcibly replenish toner based on information relating to toner consumption during stabilization control, and after the end of the stabilization control operation based on the determination result of the toner forcible replenishment determination means An image forming apparatus, comprising: a toner forcible replenishing unit that forcibly replenishes toner.

  (2) The stabilization control is performed using the toner pattern image formed with color toner even during the period in which the monochrome mode image formation is continued. The image forming apparatus according to (1), wherein when the stabilization control has been performed a predetermined number of times or more during a period in which image formation in the mode is continued, it is determined to perform color toner forcible replenishment. .

  (3) A toner forcible replenishment amount setting unit that sets a toner forcible replenishment amount based on the stabilization control history, wherein the toner forcible replenishment unit sets the toner replenishment set by the toner forcible replenishment amount setting unit. The image forming apparatus according to (1) or (2), wherein the toner is forcibly supplied based on the amount.

  (4) A toner replenishing method for an image forming apparatus that controls the stabilization of an image to be formed by forming a toner pattern image on an image carrier and detecting the toner pattern image or the transferred toner pattern image. In the toner forcible replenishment determination step for determining whether or not to forcibly replenish the toner based on the information on the toner consumption during the stabilization control, and the stabilization control based on the determination result of the toner forcible replenishment determination step. And a toner forcible replenishing step for forcibly replenishing toner after the operation of the toner is completed.

  (5) The stabilization control is performed using the toner pattern image formed with color toner even during the period in which the monochrome mode image formation is continued. The toner replenishing method according to (4), wherein, when the stabilization control is performed a predetermined number of times or more during a period in which image formation in the mode is continued, it is determined to perform color toner forcible replenishment. .

  (6) A toner forced supply amount setting step for setting a toner forced supply amount based on the stabilization control history, wherein the toner forced supply step includes a toner supply amount set by the toner forced supply amount setting step. The toner replenishing method according to (4) or (5), wherein toner is forcibly replenished based on the above.

  According to the present invention, regardless of the print mode, the necessity of forced toner replenishment is determined according to the state of toner consumption during the execution of the stabilization control, and if necessary, the forced toner replenishment is performed. It is possible to provide an image forming apparatus and a toner replenishing method thereof that can obtain stable image quality even when switching to print modes with different consumptions. For example, even when printing in the monochrome mode is continued, it is determined whether or not the forced replenishment of color toner at the time of the stabilization control is executed based on the stabilization control execution history during that time. Stable image quality can be obtained even when switching to printing in color modes with different toner consumption.

  Hereinafter, the case where the embodiment of the image forming apparatus and the toner replenishing method according to the present invention is applied to a tandem type full-color copying machine (hereinafter referred to as “copier”) as an example of the image forming apparatus will be described as an example. This will be described with reference to the drawings.

(Overall configuration of copier)
FIG. 1 is a schematic cross-sectional view showing a main configuration example of a copying machine according to the present embodiment. As shown in FIG. 1, the copying machine 1 includes an image reading unit 10, an image forming unit 20, and a control unit 100.

  The image reading unit 10 is a known unit that reads an image of a document placed on a not-illustrated document glass plate by moving the scanner 11, and is obtained by irradiation of an exposure lamp installed in the scanner 11. The original image is imaged by an optical system and AD-converted by the CCD image sensor 12 corresponding to light of three kinds of wavelengths of red (R), green (G), and blue (B) to correspond to the original. R, G, and B image data are obtained.

  The obtained image data for each color component is subjected to various types of data processing in the control unit 100, and further to each reproduction color of Y, M, C, K (hereinafter referred to as the component number related to each reproduction color, Y, M, C, and K are added as subscripts). The converted image data is stored for each reproduction color in the image memory 100a in the control unit 100, read out for each scanning line in synchronization with the supply of the recording medium P, and exposes the photosensitive drums 51Y to 51K. This is a drive signal for a laser diode (not shown, hereinafter referred to as “LD”).

  The image forming unit 20 forms an image by a known electrophotographic method, and includes an intermediate transfer unit 40 in which an intermediate transfer belt 41 is stretched, and an upstream side in the circumferential direction facing the intermediate transfer belt 41. (Hereinafter, simply referred to as “upstream side”) to Y, M, C, and K image processing units 50Y to 50K arranged at predetermined intervals along the circumferential direction downstream side (hereinafter simply referred to as “downstream side”). It consists of.

  In addition, on the conveyance path of the recording medium P along the arrow B direction, a paper feeding unit 70 that feeds the recording medium P to the secondary transfer position of the intermediate transfer unit 40 and a secondary transfer of the intermediate transfer unit 40. And a fixing unit 80 disposed downstream of the recording medium conveyance direction.

  FIG. 2 is a schematic cross-sectional view showing a configuration example of the image forming unit 20 of the copying machine according to the present embodiment. Hereinafter, the image forming unit 20 will be described with reference to FIG.

  In the image processing units 50Y to 50K for each color of Y, M, C, and K, the exposure scanning units 60Y to 60K receive LDs (not shown) that emit laser beams in response to the drive signals output from the control unit 100, respectively. A polygon mirror (not shown) for deflecting the laser beam and exposing and scanning the photosensitive drums 51Y to 51K in the main scanning direction is provided. The image processing units 50Y to 50K include photosensitive drums 51Y to 51K, charging chargers 52Y to 52K, developing units 53Y to 53K, transfer chargers 54Y to 54K, and cleaners 55Y to 55K.

  Before the exposure, the photosensitive drums 51Y to 51K are cleaned by the cleaners 55Y to 55K to remove the remaining toner on the surface, irradiated to an eraser lamp (not shown), and then neutralized by the chargers 52Y to 52K. When charged and thus exposed to the laser beam in the charged state, electrostatic latent images are formed on the surfaces of the photosensitive drums 51Y to 51K.

  The developing devices 53Y to 53K contain a two-component developer containing each color toner at a predetermined toner density, and each electrostatic latent image is stored in each color by each color developing device 53Y to 53K. Developed with toner. As a result, Y, M, C, and K toner images are formed on the surfaces of the photosensitive drums 51Y to 51K, respectively, and the transfer chargers 54Y to 54K disposed on the back side of the intermediate transfer belt 41 at the respective transfer positions. Then, the images are sequentially transferred onto the intermediate transfer belt 41 that circulates in the arrow A direction. At this time, the image forming operation for each color is executed while shifting the timing from the upstream side toward the downstream side so that the toner image is transferred in a superimposed manner on the same position on the circulating intermediate transfer belt 41. Is done.

  The intermediate transfer belt 41 on which the toner images of the respective colors have been transferred in multiple turns further reaches the position where the intermediate transfer belt 41 comes into contact with the opposing secondary transfer roller 42 to form a transfer nip portion. The recording medium P is fed to the transfer nip portion in synchronism with the rotation of the intermediate transfer belt 41, and the toner images of the respective colors transferred onto the intermediate transfer belt 41 at the transfer nip portion are recorded on the recording medium P. Is transcribed. Reference numeral 49 denotes a cleaning blade that removes toner remaining on the intermediate transfer belt 41 after transfer to the recording medium P.

  The recording medium P onto which the toner images of the respective colors are transferred is conveyed to the fixing unit 80 in the arrow B direction. The fixing roller 81 of the fixing unit 80 includes a heater inside, and the controller 100 controls energization to the heater. The recording medium P is pressed at a high temperature by the fixing roller 81, and toner particles on the surface thereof are fused and fixed on the surface of the recording medium, and then discharged onto the paper discharge tray 82.

  In addition to controlling the normal image forming operation as described above, the control unit 100 also controls the timing and content of image stabilization control. The configuration and processing contents of the image stabilization control will be described next.

(Stabilization control)
In general, in an image forming apparatus, image stabilization control is performed so that an appropriate image can always be formed against changes in image quality due to environmental changes, changes with time, and the like. Stabilization control includes fog margin control, light intensity control, maximum density control, gamma correction control, resist control, etc., and sets process conditions such as a predetermined system speed, exposure amount, development bias, and charging potential. Thereafter, a pattern image is formed with toner on the surface of the photoreceptor or the intermediate transfer belt, the pattern is detected using a sensor, and the above-described image forming conditions are adjusted based on the detection result. Further, the toner density is calculated and toner replenishment control is performed.

  In the example of the copying machine according to the present embodiment, as shown in FIG. 1 or FIG. 2, a toner pattern image transferred onto the intermediate transfer belt 41 is detected by an IDC (Image Density Control) sensor 43. Yes. The IDC sensor is a sensor that detects image density, and an optical, ultrasonic, magnetic, or other known sensor can be used.

  Stabilization control is performed regularly. In the example of the copying machine according to the present embodiment, it is performed every 200 sheets for color printing and every 100 sheets for monochrome printing. However, even if the frequency of implementation differs, the stabilization control to be implemented is common. Regardless of the print mode, stabilization control is performed for all colors of M, C, Y, K, when the monochrome print reaches 100 sheets or when the color print reaches 200 sheets. (Toner pattern image formation) is performed.

  As a test image for toner pattern formation used at the time of stabilization control, a detection patch pattern image previously stored as data is used. Since the stabilization control operation is basically the same in both monochrome and color print modes, the same patch pattern image may be used.

The basic pattern of stabilization control is as follows.
(1) An appropriate detection patch pattern image is set based on the contents to be controlled.
(2) An image is actually formed based on the set patch pattern image.
(3) The density of the toner image of the patch pattern on which the image has been formed is detected by the IDC sensor 43.
(4) Information necessary for control is calculated from the detected image density information and the like.
(5) The target control is performed according to the obtained information.

  Details of stabilization control of image density by toner replenishment will be described later.

  FIG. 3 is an example of a flow schematically showing an example of contents and order executed as stabilization control. The control items and order executed in the stabilization control will be described with reference to FIG.

  When the stabilization control is started, the fog margin is first controlled in step S11. This is the control of the background fogging of the image. The variation due to environmental changes and changes with time is adjusted so that the created image starts to fog when a predetermined document background density is exceeded. The detection image pattern for the background fog control is developed, and the factor to be controlled and the control amount are set based on the detection result of the IDC sensor 43.

  Next, in step S12, light quantity control is performed. This is control of the exposure amount at the time of image formation. The reproducibility of the image density is adjusted by adjusting the amount of light. The detection image pattern for light quantity control is developed, and the control amount is set based on the detection result of the IDC sensor 43.

  In step S13, maximum density control is performed. This is to control the maximum density that can be formed in the image to the upper limit density that has been set. A detection image pattern for maximum density control is developed, and a factor to be controlled and a control amount are set based on the detection result of the IDC sensor 43.

  In step S14, gamma correction control is performed. This corrects a change in gradation of an image due to an environmental change or a change with time. Control is performed so that the relationship between the input and output density of an image is corrected according to process conditions and the like. A detection image pattern for gamma correction control is developed, and a factor to be controlled and a control amount are set based on the detection result of the IDC sensor 43.

  Step S15 is registration correction control. This corrects misalignment as an image, such as superposition of multicolor toner images. The next step S16 is also an operation for removing the toner transferred to the intermediate transfer belt 41 during the stabilization control.

  The general image stabilization flow has been described. Next, general toner replenishment control performed during image formation will be described in detail. The toner replenishment control for toner consumption in the stabilization control in this embodiment is called toner forced replenishment and is distinguished from general toner replenishment performed at the time of image formation, and details thereof will be described later.

(General toner replenishment control performed during image formation)
Next, a configuration example of general toner replenishment control performed during image formation will be described with reference to FIG. FIG. 4 shows general toner replenishment control performed during image formation and toner replenishment control for toner consumption in stabilization control described later, that is, toner forced replenishment control, among the functions of the control unit 100 in the present embodiment. It is an example of the functional block diagram which showed the part which concerns on.

  First, a part related to general toner replenishment control performed at the time of image formation will be described. This relates only to image density stabilization control in the stabilization control, and a toner replenishment amount is set there. On the other hand, with respect to toner forced replenishment control for toner consumption during stabilization control, which will be described later, all stabilization control operations using a toner pattern image are involved, and toner is consumed in all the stabilization control operations.

  The image density stabilization control unit 101 shown in FIG. 4 includes a CPU, a timer, a counter, a memory, and the like. The image density stabilization control unit 101 is connected to each functional block related to image density, and the entire operation of image density stabilization control by toner supply. It has a function to control. A toner adhesion amount detection unit 102 calculates the toner adhesion amount from the image density detected by the IDC sensor 43. Based on the toner adhesion amount, the image density stabilization control unit 101 controls toner replenishment in order to stabilize the image density.

  Reference numerals 111 to 113 denote functional blocks related to toner replenishment control that operate during normal printing, and indicate toner replenishment control that has been conventionally performed.

  A toner replenishment amount calculation condition storage unit 111 temporarily stores process conditions, environmental conditions, durability conditions, image conditions, and the like necessary for calculating an appropriate toner replenishment amount, and controls image density stabilization when necessary. Part 101. A toner replenishment amount calculation unit 112 calculates an appropriate toner replenishment amount for securing the image density based on information on the toner adhesion amount and necessary conditions in accordance with an instruction from the image density stabilization control unit 101. Provided to the density stabilization control unit 101. A toner replenishing unit 113 receives an instruction from the image density stabilization control unit 101 based on an appropriate toner replenishing amount and executes a toner replenishing operation.

  Reference numerals 121 to 123 denote functional blocks related to toner forced replenishment control that operate during the stabilization control, which will be described later.

  As described above, conventionally, stabilization control of image density by toner replenishment starts with calculation of toner adhesion amount, calculates toner replenishment amount based on each condition for toner replenishment amount calculation, and follows it at the time of printing. Toner replenishment will be performed. That is, based on the toner replenishment amount setting set during the stabilization control, the toner replenishment operation itself is regularly performed during normal image formation.

  FIG. 5 is a flowchart of a processing example at the time of image density stabilization control leading to setting of the toner replenishment amount. With reference to FIG. 5, the flow of processing up to setting the toner replenishment amount in general toner replenishment control will be described.

  First, in step S21, image density detection using a patch pattern image for image density detection is performed. Here, the density of each patch image is collected.

  An example of a patch pattern image for detection for image density stabilization control by toner supply is shown in FIG. In FIG. 6, reference numeral 44 denotes a patch pattern image for toner adhesion amount detection for stabilizing the image density. 1C to 3C are cyan patch images, 1Y to 3Y are yellow patch images, and 1M to 3M are patch images. Magenta patch images, 1K to 3K are black patch images.

  The pattern image 44 is developed, becomes a toner image of each color, is transferred onto the intermediate transfer belt 41, and the intermediate transfer belt 41, that is, each patch image thereon, according to the pattern running direction shown on the pattern image 44 in the figure. When the vehicle travels, each patch image sequentially passes through the IDC sensor 43, and the density of each patch image is detected by the IDC sensor 43. Here, the density of each patch image is detected in parallel by two IDC sensors.

  Returning to FIG. 5, when the density of each patch image is collected, in step S22, the toner adhesion amount detection unit 102 calculates the toner adhesion amount corresponding to the density of each patch image. In this case, the relationship between the adhesion amount and the density may be converted into data in advance for each toner color material. This is because it is unlikely that the relationship changes due to other conditions unless the characteristics of the toner itself change.

  In step S23, the toner charge amount is calculated from the toner adhesion amount obtained in step S22. Since the relationship between the toner charge amount and the toner adhesion amount varies depending on environmental conditions and process conditions, data D1 related to process conditions, data D2 related to environmental conditions, and the like are read from the toner supply amount calculation condition storage unit 111 and used.

  In step S24, the toner density of the developer is calculated from the toner charge amount obtained in step S23. Since the relationship between the toner charge amount and the toner concentration also varies depending on the durability condition and the like, the data D3 and the like are read from the toner supply amount calculation condition storage unit 111 and used.

  In step S25, the toner consumption is estimated from the toner density obtained in step S24. Since this also varies depending on the image condition in addition to the process condition, the image condition data D4 and the like are read from the toner supply amount calculation condition storage unit 111 and used.

  In this way, the toner replenishment amount calculation unit 112 obtains an estimated value of the toner consumption amount, and sets a toner replenishment amount corresponding thereto in step S26.

  This completes the setting of the toner replenishment amount as the stabilization control. Further, the image density stabilization control unit 101 issues an instruction to the toner replenishment unit 113 based on this, not during the stabilization control. The toner replenishment operation during normal printing is performed based on the toner replenishment amount set during the stabilization control.

  In this case, the toner used during normal printing is replenished. In other words, when printing is performed in the monochrome mode, only the monochrome toner is supplied.

(Problem with stabilization control in monochrome mode)
The above-described conventional toner replenishment control is described above. However, the method of regularly performing the stabilization control and controlling the toner replenishment amount at the time of printing may not be in time for toner replenishment depending on the situation. Also come out.

  For example, there is a case where stabilization control is performed while printing is being continued in the monochrome mode, such as continuous printing by FAX. In the normal color mode, all of Y, M, and C color toners and K monochrome toner are used. However, in the monochrome mode, only K monochrome toner is used, and Y, M, and C color toners are used. It is never used.

  However, even when printing is continued in a monochrome mode that uses only K monochrome toner, it is not possible to predict when color printing will be performed. Therefore, control including color printing is performed during stabilization control. That is, even when printing is continued in the monochrome mode, color toner is also consumed during the stabilization control.

  The color toner is consumed during the stabilization control, not only during the above-described image density stabilization control. Color toner is consumed during all stabilizing control operations such as fog margin control, light intensity control, and gamma correction control that create and control a toner pattern image.

  In this case, the color toner replenishment control itself is not performed since the monochrome printing is performed except during the stabilization control operation (during normal printing). Therefore, if the monochrome mode is continued for a long period of time and the stabilization control is performed several times during that time, the color toner is consumed but not replenished. It happens that the concentration goes down.

  Therefore, from the standpoint of stabilizing image density, monochrome printing continues, but if it suddenly switches to color printing, replenishment of color toner cannot catch up, leading to degradation of image quality. It can happen.

  In order to deal with such problems, in this embodiment, in addition to general toner replenishment as image density stabilization control performed during normal printing, for example, when monochrome printing continues, the color consumed by stabilization control For the toner, a forced toner supply control is provided such that the toner is forcibly supplied when a certain set condition is satisfied. This forced toner replenishment control will be described below using color toner forced replenishment control when the above-described monochrome printing is continued as an example.

(Toner forced supply control for toner consumption in stabilization control)
FIG. 4 shows a portion of the functions of the control unit 100 according to the present embodiment related to general toner replenishment control performed at the time of image formation and toner forced replenishment control for toner consumption in stabilization control as described above. It is an example of the functional block diagram which showed. A configuration example of color toner forced replenishment control for toner consumption in stabilization control will be described.

  Reference numerals 121 to 123 denote functional blocks related to the control of forced toner replenishment that operates during the stabilization control. The image density stabilization control unit 101 is also involved in toner forced supply control.

  Reference numeral 121 denotes a toner forced supply determination unit that functions as toner forced supply determination means. The forcible replenishment determination unit 121 needs to forcibly replenish toner based on the history of the stabilization control up to that point, particularly the toner consumption history when performing the stabilization control according to the instruction of the image density stabilization control unit 101. Determine sex. Reference numeral 121a denotes a counter for forced toner supply determination at the time of stabilization control, and provides information about the color toner consumption history.

  Reference numeral 122 denotes a toner forced supply amount calculation unit that functions as a toner forced supply amount setting unit. The toner compulsory replenishment amount calculation unit 122 estimates the toner consumption amount during the previous stabilization control, calculates an appropriate toner compulsory replenishment amount, and provides it to the image density stabilization control unit 101.

  Reference numeral 123 denotes a toner forcible supply unit that functions as a toner forcible supply unit. The toner compulsory replenishment unit 123 receives an instruction based on an appropriate toner compulsory replenishment amount from the image density stabilization control unit 101, and executes compulsory toner replenishment during the image density stabilization control.

The control of forced replenishment for the color toner consumed in the stabilization control is roughly performed as follows.
(1) During the stabilization control, it is determined whether or not a stage where forced replenishment of color toner has been reached has been reached.
(2) Estimate the color toner consumption amount and calculate the toner amount to be replenished.
(3) If necessary, color toner is forcibly supplied at an appropriate timing.

  An example of the color toner forcible supply control process during the stabilization control will be described with reference to FIG. FIG. 7 is a flowchart illustrating a flow of a determination process example related to color toner forced replenishment during stabilization control. At the end of the stabilization control, the forced toner replenishment determination process is started. The implementation of the forced toner replenishment process based on the execution determination will be described later with reference to FIG.

  The color toner forced supply determination is performed by the toner forced supply determination unit 121 of FIG. In step S31, a forced toner supply determination unit 121 provided in the forced toner supply determination unit 121 is checked.

The determination is made based on the count number indicated by a toner forced supply determination counter (hereinafter referred to as a determination counter) 121a. Processing for accessing the count number of the determination counter 121a is only in the following three cases.
(A) As shown in step S39, when color printing is performed, the counter becomes zero.
(B) As shown in step S35, when the color toner is forcibly supplied during the stabilization control, the counter becomes zero.
(C) As shown in step S38, the counter is incremented by 1 when the stabilization control is completed without forcibly supplying the color toner.

  Therefore, when the determination counter 121a is checked, the count number indicates how many times the stabilization control has been performed since the last color printing or the forced toner supply. Since the amount of toner consumed by the stabilization control can be set in advance, the amount of toner consumed can be estimated from the number of times of stabilization control.

  Accordingly, if an allowable stabilization control count is set based on the consumed toner amount as an allowable range that requires replenishment, a determination is made as to whether toner forced replenishment is necessary by comparing it with the count number of the determination counter 121a. It can be performed.

  In step S32, the count number of the determination counter 121a is compared with a predetermined count number to determine whether toner replenishment is necessary. This step S32 functions as a toner forced supply determination process.

  If the predetermined count number has been reached (step S32: YES), it is determined that it is necessary, and step S33 is executed. If the predetermined count number has not been reached (step S32: NO), it is determined that it is not necessary, and step S36 is executed.

  The toner forced supply amount calculation is performed by the toner forced supply amount calculation unit 122 of FIG. When it is determined in step S32 that toner forced replenishment is necessary, in step S33 functioning as a toner forced replenishment amount setting step, the color toner forced replenishment amount is calculated from the estimated value of the color toner consumption corresponding to a predetermined count.

  The toner consumption amount may not be estimated from the count number, but may be estimated using the toner adhesion amount actually obtained from the IDC sensor 43. In this case, the relationship between the color toner adhesion amount and the consumption amount may be stored, and the toner amount consumed for each stabilization control may be integrated, and determination may be made based on whether or not a predetermined value as an allowable limit is exceeded.

  The color toner forced replenishment is performed by the toner forced replenishment unit 123 of FIG. In step S34, which functions as a forced toner supply step, the forced toner supply is performed based on the toner supply amount obtained in step S33. The implementation method will be described later with reference to FIG.

  In step S35, the determination counter 121a is cleared (set to 0). This means that the toner is forcibly replenished and the counter is initialized. This completes a series of processes related to the forced toner supply until the next stabilization control starts.

  If it is determined in step S32 that toner forcible replenishment is not required, it is not necessary to calculate the color toner forcible replenishment amount in step S36. However, as described above, if the toner consumption amount is not estimated from the count number, but is estimated using the toner adhesion amount actually obtained from the IDC sensor 43, the estimated color toner consumption amount is used. The calculated necessary toner replenishment amount may be stored and integrated and used every time stabilization control is performed.

  Since it is determined in step S37 that toner forcible replenishment is not performed, nothing is performed.

  Next, in step S38, the determination counter 121a is incremented by one. This is to increase the number of counters by one because the number of times of stabilization control in which toner forced replenishment has not been performed has increased by one. This completes a series of processes relating to forced toner supply until the next stabilization control starts.

  A method for forcibly supplying toner at the end of the stabilization control will be described with reference to FIG. FIG. 8 is a flowchart illustrating an example of a flow of forced toner replenishment during stabilization control.

  In response to the execution determination in step S32 in FIG. 7, first, step S43 is executed.

  In step S43, color virtual paper is created and registered in order to move the developing device. Although it does not actually form an image, it is appropriate to use A4Y paper according to the image forming area width. This is just an apparent operation just to move the developer.

  Next, in step S44, the developing device is driven based on the virtual paper in step S43. When the developing device is driven, toner replenishment is automatically executed. The toner replenishment control may be performed in the same way as during normal printing. The toner replenishment amount is based on the toner replenishment amount obtained in step S33 of FIG.

  In step S45, it is determined whether the control of the virtual paper is finished. If completed (step S45: YES), the toner forced supply process is terminated, the process returns to FIG. 7, and the process proceeds to step S35. If not finished yet (step S45: NO), the process returns to step S44, and the developing device driving, that is, the toner supply process is continued until the process is finished.

(Forced toner supply during stabilization control in monochrome mode)
With reference to FIG. 9, a description will be given of the state of countermeasures by forced replenishment of color toner for the problem of insufficient color toner replenishment due to stabilization control in monochrome mode. FIG. 9 shows the situation when printing in the color mode or monochrome mode is repeated with respect to the print number axis.

  FIG. 9A shows a case where normal color printing is continuously performed. In this case, stabilization control is performed for every 200 prints. The horizontal axis 200a indicates the number of prints, and 201a indicates the separation of every 200 color prints, that is, the execution timing of stabilization control.

  202a and 203a indicate whether or not toner forced replenishment is performed and the count number of the determination counter 121a, respectively. The count number of the determination counter 121a is always 0, and is a predetermined count number (in this case, 5 times). The toner is not forcibly replenished.

  Reference numerals 204a and 205a respectively indicate changes in the monochrome toner density and the color toner density, and both are normally controlled, and the characteristics of both are basically the same.

  In FIG. 9A, monochrome toner and color toner are both consumed and replenished during normal printing, and there is no influence of toner consumption particularly during stabilization control.

  FIG. 9B shows a case where normal color printing is continuously performed after monochrome printing is continuously performed. In this case, during the period when the first half monochrome printing is continued, the influence of toner consumption during the stabilization control appears on the color toner density.

  In the case of monochrome printing, stabilization control is performed for every 100 prints. The horizontal axis 200b indicates the number of prints, and 201b indicates a separation for every 100 sheets in the first half of the monochrome print and every 200 sheets in the latter half of the color print, that is, the timing for performing the stabilization control.

  Reference numerals 202b and 203b indicate whether toner is forcibly replenished and the count number of the determination counter 121a, respectively. The count number of the determination counter 121a increases once for each stabilization control during monochrome printing. I'm talking. However, once it switches to color printing, it immediately becomes 0, and the count number 0 is maintained during color printing. Therefore, the predetermined count number of 5 is not reached, and in this case as well, toner forced replenishment is not performed.

  Reference numerals 204b and 205b schematically show changes in the monochrome toner density and the color toner density. The monochrome toner 204b is the same as the case (204a) in which normal color printing in FIG. 9A is continuously performed.

  However, for the 205b color toner, during the period in which the first half of the monochrome printing is continued, every time the stabilization control for every 100 sheets is performed, the count number of the determination counter 121a increases. The density of the color toner is decreasing.

  For this reason, from the viewpoint of stabilization of image density, monochrome printing continues, but if it suddenly switches to color printing, replenishment of color toner cannot catch up, leading to degradation of image quality. It is also possible that this will happen.

  However, the toner supply starts and the toner density quickly recovers by switching to color printing within the predetermined count number, that is, while the toner density drop is within the allowable range.

  FIG. 9C shows a case where monochrome printing is continuously performed. In this case, stabilization control is performed for every 100 prints. However, for color toner that is not replenished with toner during monochrome printing, the influence of toner consumption particularly during stabilization control appears.

  In the case of monochrome printing, stabilization control is performed for every 100 prints. The horizontal axis 200a indicates the number of prints, and 201a indicates the separation for every 100 monochrome prints, that is, the execution timing of the stabilization control.

  202c and 203c indicate whether or not toner compulsory replenishment is performed and the count number of the determination counter 121a, respectively. The count number of the determination counter 121a is continuous for monochrome printing. It is increasing one by one. Of course, no toner is forcibly supplied.

  In the case of this figure, it is shown that the toner is forcibly replenished initially, but thereafter, the count number of the determination counter 121a is increasing, and the first stabilization after reaching the predetermined count number of 5 times. The toner is forcibly replenished during the control, and the count number of the determination counter 121a returns to zero.

  Reference numerals 204c and 205c schematically indicate changes in the monochrome toner color and the color toner density, but for the color toner 205c, the count number of the determination counter 121a increases during the period when the monochrome printing is continued. Corresponding to the above, the density of the color toner gradually decreases every time the stabilization control for every 100 sheets is performed.

  However, when the count number of the determination counter 121a reaches the predetermined count number 5, the forced toner replenishment is performed during the stabilization control, that is, the forced toner replenishment is performed because the decrease in toner density reaches the allowable range limit. As a result, the considerably reduced toner density is quickly recovered.

  By controlling toner forcible replenishment during stabilization control in this way, even in situations where monochrome printing continues and color toner starts to run out, it is possible to always ensure a toner density within an allowable range, and when switching to color printing. However, a stable color image density can be obtained.

  In this embodiment, the tandem full-color copying machine has been described as an example. However, the image forming apparatus to which the present invention is applied may be of any type, such as a copying machine, a printer, a FAX, or a complex machine thereof. In addition, the development method, transfer method, and other image forming process conditions can be variously modified.

  Each setting condition related to stabilization control of the image density, such as determination of the count number of the determination counter and a patch image, can be set in addition to those presented in the present embodiment.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modified forms are allowed within the scope as long as they are in accordance with the gist of the present invention.

1 is a schematic cross-sectional view showing a main configuration example of a copying machine according to an embodiment. FIG. 2 is a schematic cross-sectional view illustrating a configuration example of an image forming unit 20 in FIG. 1. It is a flowchart which shows roughly the example of the content and order implemented as stabilization control. FIG. 2 is a functional block diagram illustrating a configuration example of a part related to stabilization control of image density by toner replenishment among functions of a control unit 100 in FIG. 1. 10 is a flowchart illustrating a flow of a processing example up to setting of a toner replenishment amount during image density stabilization control by toner replenishment. It is a figure which shows the example of the patch pattern image for a detection for image density stabilization control. 10 is a flowchart illustrating a flow of a color toner forced supply determination process example during stabilization control. 6 is a flowchart illustrating an example of a flow of toner forcible replenishment during stabilization control. An example of a situation change when printing in the color mode or the monochrome mode is repeated is illustrated with respect to the print number axis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Copier 10 Image reading part 20 Image formation part 40 Intermediate transfer part 41 Intermediate transfer belt 42 Secondary transfer roller 43 IDC sensor 44 Patch pattern image for toner adhesion amount detection 49 Cleaning blade 50Y, 50M, 50C, 50K Image process part 51Y, 51M, 51C, 51K Photoconductor drum 52Y, 52M, 52C, 52K Charger charger 53Y, 53M, 53C, 53K Developer 54Y, 54M, 54C, 54K Transfer charger 55Y, 55M, 55C, 55K Cleaner 60Y, 60M, 60C , 60K exposure scanning unit 70 paper feeding unit 80 fixing unit 81 fixing roller 82 paper discharge tray 100 control unit 100a image memory 101 image density stabilization control unit 102 toner adhesion amount detection unit 111 toner supply amount calculation condition storage unit 112 toner supply Calculator 113 toner supply section 121 forced toner replenishing judgment unit 121a forced toner replenishing determining counter 122 forced toner supply amount calculation section 123 forced toner replenishing portion

Claims (6)

In an image forming apparatus that controls the stabilization of an image to be formed by forming a toner pattern image on an image carrier and detecting the toner pattern image or the transferred toner pattern image.
Toner forced replenishment determination means for determining whether or not to forcibly replenish toner based on information on toner consumption during the stabilization control;
An image forming apparatus comprising: a toner forcible replenishing unit that forcibly replenishes toner after the stabilization control operation ends based on a determination result of the toner forcible replenishment determining unit. The stabilization control is
Even during a period in which image formation in the monochrome mode continues, the toner pattern image formed with color toner is used,
The toner forced replenishment determining means is
2. The image formation according to claim 1, wherein during the period in which the image formation in the monochrome mode continues, when the stabilization control is performed a predetermined number of times or more, it is determined that the color toner is forcibly replenished. apparatus. A toner forced supply amount setting means for setting a toner forced supply amount based on the history of the stabilization control;
The toner forced supply means
The image forming apparatus according to claim 1, wherein the toner is forcibly supplied based on a toner supply amount set by the toner forced supply amount setting unit. In a toner replenishing method for an image forming apparatus that controls the stabilization of an image to be formed by forming a toner pattern image on an image carrier and detecting the toner pattern image or the transferred toner pattern image.
A toner forcible replenishment determination step for determining whether or not to forcibly replenish toner based on information on toner consumption during the stabilization control;
A toner replenishment method, comprising: a toner forced replenishment step of performing toner replenishment after completion of the stabilization control operation based on a determination result of the toner forced replenishment determination step. The stabilization control is
Even during a period in which image formation in the monochrome mode continues, the toner pattern image formed with color toner is used,
The toner forced supply determination step includes
5. The toner supply according to claim 4, wherein the toner supply is determined to be forcibly replenished when the stabilization control is performed a predetermined number of times or more during a period in which the monochrome mode image formation is continued. Method. A toner forced supply amount setting step for setting a toner forced supply amount based on the stabilization control history;
The toner forced replenishment step includes
6. The toner replenishing method according to claim 4, wherein the toner is forcibly replenished based on the toner replenishment amount set in the toner forcible replenishment amount setting step.

Images