JP2012048148A - Toner replenish control system and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner replenish control system which replenishes toner by distributing a right replenishing amount of toner to a right position in accordance with a calculation to equalize a toner concentration in a developing unit.SOLUTION: A toner replenishing control system to replenish a developing unit of imaging means with toner comprises: a first toner replenishing port and a second toner replenishing port to feed the toner into the developing unit; toner concentration detection means to detect a toner concentration inside the developing unit; a consumption calculation section (a replenishing amount calculation section) to obtain image information on writing means and to calculate a toner replenishing amount from the obtained image information; and a sensor calculation section (an FB controller) to calculate the toner replenishing amount from the toner concentration detected by the toner concentration detection means. Thus, because the toner replenishing control system can accurately replenish the developing unit with the right replenishing amount of toner at a right time, the system can replenish the toner by distributing the right replenishing amount of toner to equalize the toner concentration inside the developing unit to a right position based on the calculated result.

Description

  The present invention relates to a toner replenishment control system for replenishing toner to a developing portion of an image forming apparatus, and image forming such as a copying machine, a printer, a facsimile apparatus having the toner replenishment control system, or a multifunction machine having these functions. Relates to the device.

  In an image forming method or an image forming apparatus using toner as a developer, it is important to maintain a constant toner density in a developing device in order to form a high quality image. Therefore, when replenishing toner, it is desirable to replenish a necessary amount at a location where toner is consumed. Currently, as a mainstream method, toner is replenished based on output image information. This is because the image information is information that is directly related to the amount of consumed toner and has high accuracy. However, in toner replenishment driving, it is difficult to replenish an accurate amount because the toner is powder. This naturally includes machine differences. In order to guarantee image quality, it is necessary to cope with environmental conditions such as temperature and humidity, and user settings. Therefore, the toner density by the sensor is detected, and replenishment based on the result is also performed. A toner replenishing system based on these two concepts is the mainstream technology at the present time and is already known.

  However, in the conventional toner replenishment system, the toner replenishment amount obtained based on the image information and the toner replenishment amount obtained from the detection of the toner density by the sensor are added and replenished. Since the basis for calculating each replenishment amount is originally different, the replenishment timing and replenishment amount should be different. The sum of the individually calculated toner replenishment amounts erases information on the optimal timing or replenishment amount, which is an obstacle to bringing the toner density in the developing device closer to the ideal state. There was a problem.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-91785) discloses feed-forward (FF) control using image information and feedback using a toner density sensor for the purpose of keeping the toner density in the developing device constant. (FB) A configuration is disclosed in which the control is combined, the toner supply amount is calculated for each, and the final toner supply amount is calculated by adding and subtracting both.

In the configuration described in Patent Document 1, the final necessary toner replenishment amount is obtained from the FF control for calculating the necessary toner replenishment amount based on the image information and the FB control for calculating the necessary toner consumption amount by detecting the toner density. Calculated.
However, as in the problem of the prior art described above, since the necessary toner replenishment amount is finally added and replenished, information on the consumed position and amount of image information or sensor detection The problem that information such as the timing and the amount of toner required disappears cannot be solved.

  The present invention has been made in view of the above circumstances, and in order to make the toner density in the developing device constant, the toner to be supplied by distributing the necessary toner replenishment amount to the necessary position based on the calculated calculation An object of the present invention is to provide a replenishment control system, and further to provide an image forming apparatus including the toner replenishment control system.

In order to achieve the above object, the present invention adopts the means described in the following [1] to [8].
[1]: A latent image is formed on a charged image carrier based on image information by a writing unit, and the latent image on the image carrier is developed with a developer toner of a developing unit to be visualized. And a toner replenishment control system for replenishing toner to the developing means used in an image forming apparatus for transferring the visible image directly to a recording material or via an intermediate transfer member. The image information of one toner supply port, the second toner supply port, the toner density detecting means for detecting the toner density in the developing means, and the writing means is acquired, and the toner is supplied from the acquired image information It has a consumption calculation part for calculating the amount, and a sensor calculation part for calculating the toner replenishment amount from the detection value of the toner density detecting means (claim 1).
[2]: In the toner replenishment control system according to [1], both the first toner replenishing port and the second toner replenishing port are arranged in the toner circulation direction with respect to the developer circulation direction in the developing unit. It is arranged upstream of the concentration detection means (claim 2).
[3]: In the toner replenishment control system according to [1], the toner is provided between the first toner replenishing port and the second toner replenishing port with respect to the developer circulation direction in the developing unit. A density detecting means is arranged (claim 3).
[4]: In the toner replenishment control system according to any one of [1] to [3], the amount of toner replenished from the first toner replenishing port is calculated by the consumption calculating unit, The calculation of the amount of toner supplied from the second toner supply port is performed by the sensor calculation unit, or the calculation of the amount of toner supplied from the first toner supply port is performed by the sensor calculation unit. The calculation of the amount of toner replenished from the second toner replenishing port is performed by the consumption calculation unit (claim 4).
[5]: In the toner supply control system according to any one of [1] to [3], the amount of toner supplied from the first toner supply port and the second toner supply port is calculated. It is carried out after being distributed to each of the replenishment amount distribution calculation section (claim 5).
[6]: In the toner supply control system according to any one of [1] to [5], separate toner supply paths are provided to the first toner supply port and the second toner supply port, respectively. (Claim 6).
[7]: In the toner supply control system according to any one of [1] to [5], any one of the toner supply paths is defined by the first toner supply port and the second toner supply port. It supplies by making it branch (Claim 7).
[8]: Image carrier, charging means for charging the image carrier, writing means for forming a latent image on the charged image carrier based on image information, and on the image carrier In the image forming apparatus, the image forming apparatus includes: a developing unit that develops the latent image of the toner with a developer toner to make a visible image; and a transfer unit that transfers the visible image directly or via an intermediate transfer member to the recording material. The toner supply control system according to any one of claims 1 to 7 is provided as means for supplying toner to the means (claim 8).

  In the present invention, at least two or more toner replenishing ports of the developing unit of the developing unit are provided, and the replenishment based on the image information and the replenishment based on the detection value of the toner density detecting unit are distributed to each, thereby providing the necessary toner replenishment. Since the amount of toner can be replenished accurately into the developing device at the required timing, the toner replenishing amount required to keep the toner density in the developing device constant is distributed to the required position based on the calculated calculation. Thus, the toner density can be kept constant.

1 is a schematic configuration diagram illustrating a configuration example of a printer according to an embodiment of an image forming apparatus of the present invention. FIG. 2 is a schematic diagram illustrating a configuration example of a process unit for generating a Y toner image of the printer illustrated in FIG. 1. FIG. 4 is an explanatory diagram illustrating a cross-sectional configuration example of a development unit configured to circulate a two-component developer in a developer circulation conveyance path. FIG. 3 is a functional block diagram of a mechanism that performs toner supply control according to the present invention. 4 is a graph showing a basic supply pattern of a toner supply device according to an embodiment of the present invention. 6 is a graph comparing a unit consumption waveform at a detection position of a toner density detection unit with a unit consumption waveform at a position of a toner supply port. It is a graph which shows unit consumption waveform S2 and the unit supply waveform which cancels the toner density nonuniformity by this unit consumption waveform S2. FIG. 10 is an explanatory diagram of a problem related to toner supply. FIG. 3 is a block diagram illustrating an example of a toner supply control system according to the present invention. It is explanatory drawing which shows the basic structural example of the developing unit of the Example of this invention. It is explanatory drawing which shows another example of a fundamental structure of the image development unit of the Example of this invention. 1 is a block diagram illustrating a basic configuration example of a toner supply control system according to an embodiment of the present invention. FIG. 6 is a block diagram illustrating another basic configuration example of a toner replenishment control system according to an exemplary embodiment of the present invention. FIG. 6 is an explanatory diagram regarding toner supply control according to the first exemplary embodiment. FIG. 10 is an explanatory diagram regarding toner supply control according to a second exemplary embodiment. FIG. 10 is an explanatory diagram regarding toner supply control according to a third exemplary embodiment. FIG. 10 is an explanatory diagram regarding toner supply control according to a fourth exemplary embodiment.

The present invention has the following characteristics regarding a toner replenishment control system that keeps the toner concentration in the developing device constant by supplying toner into the developing device of the developing means.
In the present invention, by providing at least two or more toner supply ports in the developing unit of the developing unit, the toner calculated based on the toner supply amount calculated based on the image information and the detection value of the toner density detecting unit. It is characterized in that the replenishment amount can be individually replenished into the developing device from different replenishment ports.
The features of the present invention described above will be described in detail below with reference to the drawings.

An embodiment in which the present invention is applied to an electrophotographic printer as an image forming apparatus will be described. First, a basic configuration example of the printer according to the present embodiment will be described.
FIG. 1 is a schematic configuration diagram illustrating a configuration example of a printer according to an embodiment of an image forming apparatus of the present invention. This printer includes four process units 1Y, IC, 1M, and 1K for yellow, cyan, magenta, and black (hereinafter referred to as Y, C, M, and K). These use Y, C, M, and K toners of different colors as image forming substances for forming an image, but the other configurations are the same.

The Y toner image formed on the photoreceptor 3Y, which is an image carrier through the later-described latent image formation and development steps, is an endless belt-like intermediate transfer member (intermediate transfer belt) of the transfer unit 40 constituting the transfer unit. ) 41 is intermediate transferred.
The drum cleaning device 4Y of the photoreceptor unit 2Y shown in FIG. 2 removes toner remaining on the surface of the photoreceptor 3Y after the intermediate transfer process. As a result, the surface of the photoreceptor 3Y subjected to the cleaning process is neutralized by a neutralizing device (not shown). By this charge removal, the surface of the photoreceptor 3Y is initialized and prepared for the next image formation.
Similarly, in the process units 1C, 1M, and 1K for other colors, C toner images, M toner images, and K toner images are formed on the photoreceptors 3C, 3M, and 3K, and are formed on the intermediate transfer belt 41. Intermediate transfer.

Below the process units 1Y, 1C, 1M, and 1K in FIG. 1, an optical writing unit 20 serving as a latent image writing unit is disposed.
The optical writing unit 20 irradiates the photoconductors 3Y, 3C, 3M, and 3K of the process units 1Y, 1C, 1M, and 1K with the laser light L emitted based on the image information. Thereby, electrostatic latent images for Y, C, M, and K are formed on the photoreceptors 3Y, 3C, 3M, and 3K, respectively.
The optical writing unit 20 deflects the laser light L emitted from the light source by the polygon mirror 21 that is rotationally driven by a motor, and passes through the photosensitive members 3Y, 3C, 3M, and 3K via a plurality of optical lenses and mirrors. Is irradiated.
Moreover, it may replace with the thing of this structure and what employ | adopted the LED array may be used.

A first paper feed cassette 31 and a second paper feed cassette 32 are disposed below the optical writing unit 20 so as to overlap in the vertical direction.
In each of these paper feed cassettes, a plurality of recording papers P, which are recording materials, are stored in a stack of recording papers, and a first paper feed roller is placed on the top recording paper P. 31a and the second paper feed roller 32a are in contact with each other. When the first paper feed roller 31a is driven to rotate counterclockwise in FIG. 1 by driving means (not shown), the uppermost recording paper P in the first paper feed cassette 31 is located on the right side of the paper feed cassette in FIG. The paper is discharged toward the paper feed path 33 arranged to extend in the vertical direction.

When the second paper feed roller 32a is rotated counterclockwise in FIG. 1 by driving means (not shown), the uppermost recording paper P in the second paper feed cassette 32 is discharged toward the paper feed path 33. The A plurality of transport roller pairs 34 are arranged in the paper feed path 33, and the recording paper P fed into the paper feed path 33 is sandwiched between the rollers of the transport roller pair 34 while being fed between the paper feed paths 33. 1 is conveyed from the lower side to the upper side in FIG. A registration roller pair 35 is disposed at the end of the paper feed path 33.
The registration roller pair 35 temporarily stops the rotation of both rollers as soon as the recording paper P sent from the conveyance roller pair 34 is sandwiched between the rollers. Then, the recording paper P is sent out toward a later-described secondary transfer nip at an appropriate timing.

  A transfer unit 40 that moves the intermediate transfer belt 41 endlessly in the counterclockwise direction in FIG. 1 while stretching the intermediate transfer belt 41 is disposed above each process unit 1Y, 1C, 1M, and 1K in FIG. In addition to the intermediate transfer belt 41, the transfer unit 40 includes a belt cleaning unit 42, a first bracket 43, a second bracket 44, and the like. Also provided are four primary transfer rollers 45Y, 45C, 45M, 45K, a secondary transfer backup roller 46, a drive roller 47, an auxiliary roller 48, a tension roller 49, and the like. The intermediate transfer belt 41 is endlessly moved counterclockwise in FIG. 1 by the rotational driving of the driving roller 47 while being stretched around these rollers.

  The four primary transfer rollers 45Y, 45C, 45M, and 45K sandwich the intermediate transfer belt 41 that moves endlessly between the photoreceptors 3Y, 3C, 3M, and 3K to form primary transfer nips, respectively. Yes. A transfer bias having a polarity opposite to that of the toner (in this embodiment, a positive polarity) is applied to the inner peripheral surface of the intermediate transfer belt 41. As the endless movement of the intermediate transfer belt 41 passes through the primary transfer nips for Y, C, M, and K, the photosensitive drums 3Y, 3C, 3M, and 3K are disposed on the outer peripheral surface thereof. The upper color toner images are primarily transferred so as to overlap each other. As a result, a four-color superimposed toner image (hereinafter referred to as “four-color toner image”) is formed on the intermediate transfer belt 41.

  The secondary transfer backup roller 46 sandwiches the intermediate transfer belt 41 with the secondary transfer roller 50 disposed outside the loop of the intermediate transfer belt 41 to form a secondary transfer nip. The registration roller pair 35 described above feeds the recording paper P sandwiched between the rollers toward the secondary transfer nip at a timing at which the recording paper P can be synchronized with the four-color toner image on the intermediate transfer belt 41. The four-color toner image on the intermediate transfer belt 41 is affected by the secondary transfer electric field formed between the secondary transfer roller 50 to which the secondary transfer bias is applied and the secondary transfer backup roller 46, and the influence of the nip pressure. Secondary transfer is performed collectively on the recording paper P in the secondary transfer nip. Then, combined with the white color of the recording paper P, a full color toner image is obtained.

  Untransferred toner that has not been transferred to the recording paper P adheres to the intermediate transfer belt 41 after passing through the secondary transfer nip. This is cleaned by the belt cleaning unit 42. In the belt cleaning unit 42, the cleaning blade 42a is brought into contact with the surface of the intermediate transfer belt 41, whereby the transfer residual toner on the belt is scraped off and removed.

The first bracket 43 of the transfer unit 40 swings at a predetermined rotation angle about the rotation axis of the auxiliary roller 48 as the solenoid (not shown) is turned on / off.
In the case of forming a monochrome image, the printer according to the present embodiment rotates the first bracket 43 a little counterclockwise in the drawing by driving the solenoid described above.
By this rotation, the Y, C, and M primary transfer rollers 45Y, 45C, and 45M are revolved counterclockwise in the drawing around the rotation axis of the auxiliary roller 48, whereby the intermediate transfer belt 41 is moved to the Y direction. , C and M photoconductors 3Y, 3C and 3M.
Of the four process units 1Y, 1C, 1M, and 1K, only the K process unit 1K is driven to form a monochrome image.
Accordingly, it is possible to avoid exhaustion of the process units due to wastefully driving the process units for Y, C, and M during monochrome image formation.

A fixing unit 60 as a fixing unit is disposed above the secondary transfer nip in the figure. The fixing unit 60 includes a pressure heating roller 61 that includes a heat source such as a halogen lamp, and a fixing belt unit 62.
The fixing belt unit 62 includes a fixing belt 64, a heating roller 63 containing a heat source such as a halogen lamp, a tension roller 65, a driving roller 66, a temperature sensor (not shown), and the like. Then, the endless fixing belt 64 is endlessly moved in the counterclockwise direction in FIG. 1 while being stretched by the heating roller 63, the tension roller 65, and the driving roller 66. In the process of endless movement, the fixing belt 64 is heated from the back side by the heating roller 63. A pressure heating roller 61 that is rotationally driven in the clockwise direction in FIG. 1 is in contact with the surface of the fixing belt 64 that is heated in this manner. Thereby, a fixing nip where the pressure heating roller 61 and the fixing belt 64 abut is formed.

Outside the loop of the fixing belt 64, a temperature sensor (not shown) is disposed so as to face the surface of the fixing belt 64 with a predetermined gap, and the surface temperature of the fixing belt 64 immediately before entering the fixing nip is determined. Detect.
This detection result is sent to a fixing power supply circuit (not shown). The fixing power supply circuit performs on / off control of power supply to the heat generation source included in the heating roller 63 and the heat generation source included in the pressure heating roller 61 based on the detection result by the temperature sensor.
As a result, the surface temperature of the fixing belt 64 is maintained at about 140.degree. The recording paper P that has passed through the secondary transfer nip is separated from the intermediate transfer belt 41 and then fed into the fixing unit 60. Then, in the process of being conveyed from the lower side to the upper side in the drawing while being sandwiched by the fixing nip in the fixing unit 60, the full-color toner image is applied to the recording paper P by being heated or pressed by the fixing belt 64. To settle.

The recording paper P subjected to the fixing process in this manner is discharged outside the apparatus after passing between the rollers of the paper discharge roller pair 67.
A stack unit 68 is formed on the upper surface of the housing of the printer main body, and the recording paper P discharged to the outside by the discharge roller pair 67 is sequentially stacked on the stack unit 68.

Above the transfer unit 40, toner cartridges 72Y, 72C, 72M, and 72K, which are four toner containers that respectively store Y toner, C toner, M toner, and K toner, are disposed. The color toners in the toner cartridges 72Y, 72C, 72M, and 72K are appropriately supplied to the developing units 7Y, 7C, 7M, and 7K of the process units 1Y, 1C, 1M, and 1K, respectively, by a toner replenishing device (not shown). .
The toner cartridges 72Y, 72C, 72M, and 72K are detachable from the printer main body independently of the process units 1Y, 1C, 1M, and 1K.

  In FIG. 1, a printer is described as an example. However, if a document image reading unit (scanner unit) is installed above the stack unit 68 of the printer in FIG. Further, if it is connected to an external line (telephone line or optical line) or a local area network (LAN) with a communication function, it can be used as a facsimile machine or a digital multifunction machine.

  FIG. 2 is a schematic diagram showing a configuration example of a process unit for generating a Y toner image of the printer shown in FIG. The process unit 1Y includes a photoreceptor unit 2Y and a developing unit (developing device) 7Y that constitutes a developing unit. The photoconductor unit 2Y and the developing unit 7Y are configured to be detachable from the printer main body as a process unit 1Y. However, the developing unit 7Y can be attached to and detached from the photosensitive unit 2Y in a state where it is detached from the printer main body.

  The photoreceptor unit 2Y includes a drum-shaped photoreceptor 3Y as an image carrier, a drum cleaning device 4Y, a static eliminator (not shown), a charging device 5Y, and the like. The charging device 5Y, which is a charging means, uniformly charges the surface of the photoreceptor 3Y, which is driven to rotate clockwise in FIG. 2 by a driving means (not shown), with the charging roller 6Y. Specifically, a charging bias is applied from a power source (not shown) to the charging roller 6Y that is driven to rotate counterclockwise in FIG. 2, and the charging roller 6Y is brought close to or in contact with the photosensitive member 3Y, whereby the photosensitive member 3Y. Is uniformly charged.

Instead of the charging roller 6Y, another charging member such as a charging brush may be used in proximity or contact.
In addition, a charger that uniformly charges the photoreceptor 3Y by a charger method, such as a scorotron charger, may be used.

  The surface of the photoreceptor 3Y uniformly charged by the charging device 5Y is exposed and scanned by a laser beam emitted from an optical writing unit 20 serving as a latent image writing unit (latent image forming unit) described later, and is electrostatically latent for Y. Carry an image.

FIG. 3 is an explanatory diagram illustrating a cross-sectional configuration example around the developer circulation conveyance path of the development unit configured to circulate the two-component developer in the developer circulation conveyance path.
As shown in FIGS. 2 and 3, the developing unit 7Y, which is a developing device of the developing means, has a first agent containing portion 9Y in which a first conveying screw 8Y as a developer conveying means is disposed. Further, a toner density detecting means (toner density sensor) 10Y comprising a magnetic permeability sensor as a toner density detecting means, a second conveying screw 11Y as a developer conveying means, a developing sleeve 12Y as a developer carrying member, a developer regulating member. The second agent accommodating portion 14Y in which a doctor blade 13Y or the like is disposed is also provided. In these two agent storage portions, a Y developer (not shown) which is a two-component developer composed of a magnetic carrier and a negatively chargeable Y toner is included.

  The first conveying screw 8Y is rotationally driven by a driving unit (not shown) to convey the Y developer in the first agent accommodating portion 9Y to the front side in FIG. The Y developer in the middle of conveyance is from a portion (hereinafter referred to as “replenishment portion”) facing the toner replenishing port 17Y in the first agent storage portion 9Y by the toner concentration detection means 10Y fixed on the first conveyance screw 8Y. Also, the toner concentration of the Y developer passing through a predetermined detection position located upstream in the developer circulation direction is detected. Then, the Y developer conveyed to the end of the first agent accommodating portion 9Y by the first conveying screw 8Y enters the second agent accommodating portion 14Y through the communication port 18Y.

  The second conveying screw 11Y in the second agent accommodating portion 14Y is rotationally driven by a driving means (not shown) to convey the Y developer to the back side in FIG. In this way, the developing sleeve 12Y is arranged in a posture parallel to the second conveying screw 11Y above the second conveying screw 11Y that conveys the Y developer in FIG. The developing sleeve 12Y includes a magnet roller 16Y fixedly disposed in a developing roller 15Y made of a non-magnetic sleeve that is driven to rotate counterclockwise in FIG. A part of the Y developer conveyed by the second conveying screw 11Y is pumped up to the surface of the developing roller 15Y by the magnetic force generated by the magnet roller 16Y.

Then, after the thickness of the layer is regulated by a doctor blade 13Y arranged so as to maintain a predetermined gap from the surface of the developing roller 15Y, the layer is conveyed to a developing region facing the photosensitive member 3Y, and is transferred onto the photosensitive member 3Y. Y toner is adhered to the electrostatic latent image for Y. This adhesion forms a Y toner image on the photoreceptor 3Y.
The Y developer that has consumed Y toner by the development is returned onto the second conveying screw 11Y as the developing roller 15Y rotates. Then, the Y developer conveyed to the end of the second agent accommodating portion 14Y by the second conveying screw 11Y returns to the first agent accommodating portion 9Y through the communication port 19Y. In this way, the Y developer is circulated and conveyed in the developing unit.

Hereinafter, a toner replenishment control system which is a characteristic part of the present invention will be described.
Since the contents of the toner replenishment control system are the same for each color, the following description will be given taking Y toner replenishment control as an example.

  In the toner replenishment control system of the present embodiment, an amount of Y toner necessary for maintaining the toner concentration of the Y developer within the target toner concentration range is replenished from the toner replenishing port 17Y. However, in the present embodiment, the amount of Y toner from the location facing the toner supply port 17Y (supply location) to the location where the Y developer is supplied to the developing sleeve 12Y (second agent storage portion 14Y). Specifically, the toner concentration of the Y developer passing through a measurement location B, which will be described later, is an arbitrary location (specific location) located between the replenishment location and the upstream end of the second agent container 14Y in the developer circulation direction. The toner replenishment amount at the replenishment point is adjusted so that there is no time change. As shown in FIG. 4, the adjustment of the toner replenishment amount at the replenishment point is performed by driving a drive source 71Y that drives the toner replenishment member of the toner replenishing device 70 by the replenishment control unit 102 of the control unit 100 functioning as a replenishment control unit. This is done by controlling timing, driving time, driving speed, and the like. Any known toner replenishing member can be used as long as it can adjust the toner supply from the toner replenishing port 17Y to the Y developer by the driving force of the drive source 71Y.

FIG. 4 is a functional block diagram of a mechanism for performing toner supply control according to the present invention.
The detection result of the toner concentration of the Y developer by the toner concentration detection means 10Y is sent as an electric signal to the control unit 100 (not shown).
The control unit 100 includes a CPU (Central Processing Unit) that is a calculation unit, a RAM (Random Access Memory) that is a data storage unit, a ROM (Read Only Memory), and the like, and performs various types of calculation processes and control programs. It can be carried out. The control unit 100 stores the Vtref for Y, which is the target value of the output voltage from the toner density detecting means 10Y, and the toner density detecting means 10C, 10M mounted in the other developing units 7C, 7M, 7K in the RAM. The data of C Vtref, M Vtref, and K Vtref, which are target values of the output voltage from 10K, are stored.

For the Y developing unit 7Y, the value of the output voltage from the toner density detecting means 10Y is compared with the Y Vtref, and an amount of Y toner corresponding to the comparison result is supplied from the toner supply port 17Y. The drive source 71Y of the toner replenishing device 70 is controlled.
With this control, an appropriate amount of Y toner is supplied to the Y developer whose Y toner density has decreased due to the consumption of Y toner during development in the first agent storage unit 9Y. For this reason, the toner concentration of the Y developer in the second agent container 14Y is maintained within the target toner concentration range. The same applies to the developers in the developing units 7C, 7M, and 7K for other colors. The toner replenishment control in this embodiment is performed so as to cancel out the toner density unevenness, and details thereof will be described later.

  The replenishment control unit 102 controls one drive source 71Y of the toner replenishing device 70 based on the prediction data calculated by the prediction data calculation unit 101 of the control unit 100 that functions as a prediction data calculation unit.

Here, the prediction data calculation unit 101 uses the calculation program and calculation table stored in the ROM based on the detection result of the toner concentration detection unit 10Y, and the toner concentration time of the Y developer at the measurement location B described later. Change prediction data is calculated. Then, the replenishment control unit 102 of the control unit 100 functioning as a replenishment control unit performs drive control of one drive source 71Y with a combination of unit replenishment patterns, which will be described later, based on the prediction data calculated by the prediction data calculation unit 101. This eliminates uneven toner density.
The unit supply pattern can be obtained by conducting an experiment or the like in advance. Hereinafter, a specific procedure for creating a unit supply pattern will be described.

A basic pattern (hereinafter referred to as “replenishment basic pattern”) of the toner replenishment operation by the toner replenishing device 70 is measured using the toner density detecting means 10Y in FIG.
FIG. 5 is a graph showing a basic supply pattern of the toner supply device 70 in the present embodiment.
Each of the waveforms H1, H2, H3, H4, and H5 indicates the amount of toner that is replenished by a single drive operation of the drive source 71Y (hereinafter referred to as “replenishment operation”) with respect to the Y developer without toner density unevenness. (Hereinafter referred to as “unit replenishment amount”) A waveform indicating the result of detecting a change in toner density over time at a measurement location B by a measurement sensor when toner is replenished with five replenishment patterns different from each other (hereinafter “ It is called “Replenishment basic waveform”. The unit replenishment amount increases in the order of the replenishment basic waveforms H1, H2, H3, H4, and H5. The unit replenishment amount can be varied by changing the drive time and drive speed of the drive source 71Y in one replenishment operation.

Next, the unit consumption waveform at the detection location of the toner density detecting means 10Y and the unit consumption waveform at the position of the toner supply port 17Y are measured.
FIG. 6 is a graph comparing the unit consumption waveform at the detection location of the toner density detection means 10Y with the unit consumption waveform at the position of the toner supply port 17Y. Each of the unit consumption waveforms S1 and S2 shown in FIG. 6 prints the same unit image corresponding to the unit area for detecting the toner density on the recording paper P, using the Y developer with no toner density unevenness. 6 is a waveform (this is referred to as a “unit consumption waveform”) indicating a detection result when each sensor detects a temporal change in toner density without supplying toner after Y toner is consumed. The unit area for detecting the toner density when obtaining the unit consumption waveforms S1 and S2 is ideally one dot area of the image information, but in reality, it is influenced by the resolution of the sensor, noise, or the toner replenishing device 70. Therefore, it is preferable to determine a unit area for toner density detection that can be set as small as possible in consideration of these factors.

  In FIG. 6, when the two unit consumption waveforms S1 and S2 are compared, the half width (broad state) and the minimum toner density are different from each other. This is due to the difference in the amount of stirring received from the first conveying screw 8Y while the Y developer that consumed Y toner is conveyed to each position due to the difference in each position.

Next, a unit supply waveform that cancels out the toner density unevenness due to the unit consumption waveform S2 is obtained. FIG. 7 is a graph showing a unit consumption waveform S2 and a unit supply waveform that cancels out uneven toner density due to the unit consumption waveform S2.
From the unit consumption waveform S2 at the position of the toner supply port 17Y and the basic supply waveforms H1, H2, H3, H4, and H5, a unit supply waveform H ′ that cancels the unit consumption waveform S2 is represented as each basic supply waveform H1, Created by combining H2, H3, H4, and H5. Here, the unit consumption waveform S2 indicates a change in toner density over time when the Y developer passes through the measurement location B after developing a latent image corresponding to a unit area for toner density detection. On the other hand, each of the basic supply waveforms H1, H2, H3, H4, and H5 indicates that the Y developer that has received the toner supply passes through the measurement point B when the supply operation with different unit supply amounts is performed only once. The change in toner density over time is shown. Accordingly, as shown in FIG. 7, the toner is such that the unit supply waveform H ′ obtained by appropriately combining the supply basic waveforms H1, H2, H3, H4, and H5 has a waveform close to a waveform corresponding to the opposite phase of the unit consumption waveform S2. If the replenishment operation is performed, the toner density unevenness of the Y developer after passing through at least the position of the toner replenishment port 17Y can be eliminated. That is, the toner density unevenness can be eliminated before the Y developer, which has developed the latent image corresponding to the unit area for toner density detection, is conveyed again to the second agent container 14Y and contributes to development.

  When the unit supply waveform H ′ is obtained in this way, the toner supply operation corresponding to the combination of the basic supply waveforms H1, H2, H3, H4, and H5 constituting the unit supply waveform H ′ becomes the unit supply pattern. In the graph shown in FIG. 7, the replenishment operation of the second replenishment basic waveform H2 is performed, then the replenishment operation of the third replenishment basic waveform H3 is performed, and finally the replenishment operation of the second replenishment basic waveform H2 is performed. By performing the operation, the unit supply waveform H ′ obtained by synthesizing these supply basic waveforms becomes a waveform close to a waveform corresponding to the opposite phase of the unit consumption waveform S2. That is, this toner replenishment operation becomes the unit replenishment pattern in this embodiment.

The problem relating to the toner supply described so far will be described.
In FIG. 8, the upper side of the central horizontal line is defined as having a low toner density, and the lower side is defined as having a high toner density. The horizontal axis indicates the elapsed time. In the following description, the same figures all indicate the same thing, and the description is omitted. In FIG. 8, toner consumption by image output is started from the timing of image output start, and density unevenness as shown by line a occurs. On the other hand, as shown in FIG. 3, the toner replenishing port 17Y is located far upstream with respect to the developer flow direction as compared with the position of the toner density detecting means 10Y. It will slip into. As indicated by line b from that position, replenishment in reverse phase from the image information is started. Further, in addition to this FF control function, the difference between the detected value by the toner density detecting means 10Y and the target value, and the FB replenishment calculated from the area indicated by the hatched portion of c are generated as indicated by the hatched portion of d. These two supply amounts are added together. As a result, the final toner density fluctuation has a shape as shown by a thick line e, and immediately after the start of image output, the toner density moves to the lighter side, and when replenishment is started, the toner density rapidly moves to the darker side and greatly undulates. After that, it returns to the normal state. This variation is repeated during image output, and in the case of continuous output, this single-sheet output toner density variation is superimposed. If the toner density fluctuation continues in this way, this directly affects the quality of the output image.

  The toner supply control system at this time will be described with reference to a block diagram shown in FIG. In FIG. 9, first, the toner density target value and the detected value from the toner density detecting means for detecting the current toner density are compared and input to the FB controller. The FB controller, which is a sensor calculation unit, calculates a necessary toner supply amount from the obtained comparison value. In addition, information related to the output image, such as image information of the writing means and paper information of the recording material, is input to the supply amount calculation unit. The replenishment amount calculation unit is a part (consumption calculation unit) that calculates the reverse phase toner replenishment amount and timing for offsetting the toner consumption amount and the consumption timing obtained from the image information. The toner replenishment amount obtained from the FB controller and the toner replenishment amount from the replenishment amount calculation unit are added together, and the final toner replenishment amount is obtained through a gain 1 that enables fine adjustment of the toner replenishment amount.

  In order to solve the above problems, the present invention supplies toner for detecting the toner density, replenishing the necessary replenishment amount by FB control, and performing two replenishments to replenish the necessary replenishment amount calculated from the image information to the consumption location. The system reduces the toner density fluctuation by replenishing the necessary replenishment amount from two or more replenishment ports. A specific example is shown below.

An example of the basic configuration of the developing unit (developing device) according to the embodiment of the present invention is shown in FIGS.
10 and FIG. 11 will be described while comparing with FIG. The toner replenishing port 17Y in FIG. 3 becomes a toner replenishing port (1) 17Y in FIG. At this time, in the case of FIG. 10, another toner replenishing port is provided as a toner replenishing port (2) 17Y on the upstream side with respect to the developer conveying direction of the toner density detecting means 10Y. In the case of FIG. 11, another toner replenishing port is provided as a toner replenishing port (2) 17Y on the downstream side with respect to the developer conveying direction of the toner density detecting means 10Y.

12 and 13 are block diagrams showing a basic configuration example of the toner replenishment control system according to the embodiment of the present invention.
First, in the toner replenishment control system of FIG. 12, the toner density target value and the detected value from the toner density detecting means for detecting the current toner density are compared and input to the FB controller. The FB controller, which is a sensor calculation unit, calculates a necessary toner supply amount from the obtained comparison value. The toner replenishment amount (1) is obtained through a gain 1 that enables fine adjustment of the toner replenishment amount.
Also, information related to the output image, such as image information and paper information, is input to the supply amount calculation unit. The replenishment amount calculation unit is a part (consumption calculation unit) that calculates the reverse phase toner replenishment amount and timing for offsetting the toner consumption amount and the consumption timing obtained from the image information. The toner replenishment amount (2) is obtained through a gain 2 that enables fine adjustment of the toner replenishment amount. In FIG. 12, the calculated toner supply amount is individually supplied.

  On the other hand, in the toner replenishment control system of FIG. 13, the toner density target value is compared with the detection value from the toner density detection means for detecting the current toner density and input to the FB controller. The FB controller, which is a sensor calculation unit, calculates a necessary toner supply amount from the obtained comparison value. Also, information related to the output image, such as image information and paper information, is input to the supply amount calculation unit. The replenishment amount calculation unit is a part (consumption calculation unit) that calculates the reverse phase toner replenishment amount and timing for offsetting the toner consumption amount and the consumption timing obtained from the image information. The toner replenishment amount obtained from the FB controller and the toner replenishment amount from the replenishment amount calculation unit are input to the replenishment amount distribution calculation unit. This replenishment amount distribution calculation unit determines how much toner replenishment amount (1) and toner replenishment amount (2) are to be distributed, and gain 1 and gain 2 that enable fine adjustment of toner replenishment amount, respectively. The final toner replenishment amount (1) and toner replenishment amount (2) are obtained through the above.

Here, in this embodiment, the case where there are two toner replenishing ports of the developing unit (developing device) is described, but three or more may be provided, and the number is not limited to two. Further, even when two or more toner supply ports are provided, there is no problem even if the installation position is different from that of the present embodiment.
Examples 1 to 4 of toner replenishment control will be described below.

[Example 1]
Replenishment from the toner replenishment amount (1) in FIG. 12 is performed from the toner replenishment port (1) of the developing unit of FIG. 10 or FIG. 11, and replenishment from the toner replenishment amount (2) of the development unit of FIG. An example in which the toner supply port (2) is used is Example 1. The behavior of toner replenishment control in Embodiment 1 will be described with reference to FIG.

  In FIG. 14, since the toner replenishment amount (1) is an output from the FB controller, the amount of FB replenishment calculated from the hatched area of c, which is the detection result by the toner density detecting means, is indicated by the hatched area of d. The replenishment amount is immediately. For this reason, when the toner density changes from the image output start timing to a lighter side, the toner replenishment amount is calculated accordingly, and since it is the toner replenishment port (2), it immediately begins to cancel out. Thereafter, replenishment in the reverse phase from the image information is started from the toner replenishment port (1). As a result, density unevenness due to excessive replenishment occurs as in the case of line b, but since the amount of FB replenishment is added in the initial stage, a decrease in toner density is reduced. Further, in the subsequent replenishment from the image information, the replenishment amount is reduced as compared with the case where this method is not used (FIG. 8) because the replenishment is performed based on the output image information.

  As described above, in the toner replenishment control according to the first exemplary embodiment, a necessary toner replenishment amount can be accurately replenished into the developing unit at a necessary timing, which is necessary to make the toner density in the developing unit constant. Based on the calculated calculation, a correct toner replenishment amount can be distributed and replenished to a required position, and the toner density can be kept constant.

[Example 2]
Replenishment from the toner replenishment amount (1) in FIG. 12 is performed from the toner replenishment port (2) of the developing unit of FIG. 10 or FIG. 11, and replenishment from the toner replenishment amount (2) of the development unit of FIG. An example in which the toner supply port (1) is used is Example 2. The behavior of toner supply control in the second embodiment will be described with reference to FIG.

  In FIG. 15, since the toner replenishment amount (2) is replenishment based on the reverse phase from the image information, the image output is started and the toner density is shifted to a lighter side, and there is a slight delay, but replenishment almost simultaneously. Is started. Therefore, the final density unevenness is almost reduced, and the imbalance is immediately offset by consumption and replenishment. At this time, the FB replenishment amount is calculated from the difference such as calculation error and variation detected by the toner density detecting means, and replenished from the toner replenishment port (1). There is little adverse effect on the replenishment due to the phase, and the toner density fluctuation can be greatly reduced.

  As described above, in the toner replenishment control according to the second exemplary embodiment, the necessary toner replenishment amount can be accurately replenished into the developing unit at a necessary timing, so that it is necessary to make the toner density in the developing unit constant. Based on the calculated calculation, a correct toner replenishment amount can be distributed and replenished to a required position, and the toner density can be kept constant.

[Example 3]
Replenishment from the toner replenishment amount (1) in FIG. 13 is performed from the toner replenishment port (1) of the developing unit of FIG. 10 or FIG. 11, and replenishment from the toner replenishment amount (2) of the development unit of FIG. An example in which the toner supply port (2) is used is Example 3. The behavior of toner supply control in the third embodiment will be described with reference to FIG.

  In FIG. 16, since the toner replenishment amount (1) is an output from the FB controller, the amount of FB replenishment calculated from the shaded area of c, which is the detection result by the toner density detecting means, is shown in the shaded area of d. The replenishment amount is immediately. For this reason, when the toner density changes from the image output start timing to a lighter side, the toner replenishment amount is calculated accordingly, and since it is the toner replenishment port (2), it immediately begins to cancel out. Thereafter, replenishment in the reverse phase from the image information is started from the toner replenishment port (1). At this time, since the toner concentration is on the dark side in the FB replenishment, replenishment control is performed such that consumption (consumption of the amount shown by the g line in FIG. 16 (the deviation of the area of f)) is performed from the toner concentration detection means. Done. Here, this is called minus replenishment. This minus replenishment is physically impossible to actually generate. However, since replenishment from the image information is about to be performed at this time, the replenishment amount distribution calculation unit shown in FIG. 13 performs replenishment after removing the negative replenishment from the replenishment amount from the image information. It is configured. As a result, it is possible to realize physically impossible negative replenishment, and it is possible to reduce oversupply that is a problem in the first embodiment.

  As described above, in the toner replenishment control according to the third exemplary embodiment, the necessary toner replenishment amount can be accurately replenished into the developing unit at a necessary timing, which is necessary to make the toner density in the developing unit constant. Thus, the toner replenishment amount can be distributed and replenished to a required position based on the calculated calculation, and the toner density can be kept constant as compared with the first embodiment.

[Example 4]
Replenishment from the toner replenishment amount (1) in FIG. 13 is performed from the toner replenishment port (2) of the developing unit of FIG. 10 or FIG. 11, and replenishment from the toner replenishment amount (2) of the development unit of FIG. An example in which the toner supply port (1) is used is Example 4. The behavior of toner replenishment control in Embodiment 4 will be described with reference to FIG.

  In FIG. 17, since the toner replenishment amount (2) is replenishment based on the reverse phase from the image information, image output is started and the toner density is shifted to a lighter side and there is a slight delay, but replenishment almost simultaneously. Is started. Therefore, the final density unevenness is almost reduced, and the imbalance is immediately offset by consumption and replenishment. At this time, the FB replenishment amount is calculated from the difference such as calculation error and variation detected by the toner density detecting means, and replenished from the toner replenishment port (1). There is little adverse effect on the replenishment due to the phase, and the toner density fluctuation can be greatly reduced. Furthermore, since the toner concentration is on the dark side in the FB replenishment portion here, the replenishment control to consume the amount (consumption of the portion shown by the g line (f area deviation) shown in FIG. 17) from the toner concentration detection means. Is done. Here, this is called minus replenishment. This minus replenishment is physically impossible to actually generate. However, when there is replenishment from the image information, the replenishment amount distribution calculation unit shown in FIG. 13 is configured to replenish the replenishment amount from the image information after removing the negative replenishment. As a result, it is possible to realize a physically impossible negative supply, and it is possible to reduce oversupply on the side where the toner density, which is difficult to correct compared with the second embodiment, is high.

  As described above, in the toner replenishment control according to the fourth exemplary embodiment, the necessary toner replenishment amount can be accurately replenished into the developing unit at a necessary timing, which is necessary to make the toner density in the developing unit constant. Therefore, the toner replenishment amount can be distributed and replenished to a required position based on the calculated calculation, and the toner density can be kept constant as compared with the second embodiment.

1Y, 1C, 1M, 1K: process unit 2Y: photoconductor unit 3C, 3M, 3K: photoconductor (image carrier)
4Y: Drum cleaning device 5Y: Charging device (charging means)
6Y: charging roller 7Y, 7C, 7M, 7K: developing unit (developing device (developing means))
8Y: 1st conveying screw 9Y: 1st agent accommodating part 10Y: Toner concentration detection means (toner concentration sensor)
11Y: Second conveying screw 12Y: Developing sleeve 13Y: Doctor blade 14Y: Second agent container 15Y: Developing roller 16Y: Maginet roller 17Y: Toner supply port 20: Optical writing unit (writing means)
31: First paper feed cassette 32: Second paper feed cassette 33: Paper feed path 34: Transport roller pair 35: Registration roller pair 40: Transfer unit (transfer means)
41: Intermediate transfer belt (intermediate transfer member)
42: Belt cleaning unit 43: First bracket 44: Second bracket 45Y, 45C, 45M, 45K: Primary transfer roller 46: Secondary transfer backup roller 47: Drive roller 50: Secondary transfer roller 60: Fixing unit 61: Pressure heating roller 62: Fixing belt unit 63: Heating roller 64: Fixing belt 65: Tension roller 66: Drive roller 67: Paper discharge roller pair 68: Stack unit 70: Toner supply device (toner supply means)
71Y, 71C, 71M, 71K: Drive source 100: Control unit 101: Predicted data calculation unit 102: Supply control unit (supply control means)
P: Recording paper (recording material)

JP 2010-91785 A

Claims (8)

A latent image is formed on the charged image carrier based on the image information by the writing means, and the latent image on the image carrier is developed with the developer toner of the developing means to form a visible image. In a toner replenishment control system that is used in an image forming apparatus that transfers an image directly to a recording material or via an intermediate transfer member, and replenishes toner to the developing unit,
A first toner supply port and a second toner supply port for supplying toner into the developing means;
Toner density detecting means for detecting the toner density in the developing means;
A consumption calculating unit that acquires image information of the writing unit and calculates a toner replenishment amount from the acquired image information;
A sensor calculation unit for calculating a toner replenishment amount from a detection value of the toner density detection unit;
And a toner replenishment control system. The toner replenishment control system according to claim 1.
The first toner supply port and the second toner supply port are both disposed on the upstream side of the toner density detecting unit with respect to the direction of developer circulation in the developing unit. Toner supply control system. The toner replenishment control system according to claim 1.
The toner replenishment control, wherein the toner concentration detecting means is disposed between the first toner replenishing port and the second toner replenishing port with respect to a developer circulation direction in the developing unit. system. In the toner replenishment control system according to any one of claims 1 to 3,
The calculation of the amount of toner supplied from the first toner supply port is performed by the consumption calculation unit, and the calculation of the amount of toner supplied from the second toner supply port is performed by the sensor calculation unit, or The calculation of the amount of toner supplied from the first toner supply port is performed by the sensor calculation unit, and the calculation of the amount of toner supplied from the second toner supply port is performed by the consumption calculation unit. A toner replenishment control system. In the toner replenishment control system according to any one of claims 1 to 3,
The toner replenishment control system, wherein the toner amount replenished from the first toner replenishing port and the second toner replenishing port is calculated after being dispersed by the replenishment amount distribution calculating unit. In the toner replenishment control system according to any one of claims 1 to 5,
A toner replenishment control system, wherein each of the first toner replenishing port and the second toner replenishing port has an individual toner supply path. In the toner replenishment control system according to any one of claims 1 to 5,
A toner replenishment control system, wherein either one of the first toner replenishing port and the second toner replenishing port is branched and supplied. An image carrier, charging means for charging the image carrier, writing means for forming a latent image on the charged image carrier based on image information, and a latent image on the image carrier. In an image forming apparatus having a developing unit that develops a visible image by developing with a toner of a developer, and a transfer unit that transfers the visible image to a recording material directly or via an intermediate transfer member,
An image forming apparatus comprising the toner replenishment control system according to claim 1 as means for replenishing toner to the developing means.

Images