JP2004102099A - Apparatus and method for image formation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for forming an image with good quality by accurately estimating the amount and distribution state of a residual toner on a photoreceptor after image transfer and discharging a collected toner when the toner exceeding a permissible value is collected at a portion of a cleaning device. <P>SOLUTION: An image area on the photoreceptor 11 is divided in horizontal and vertical scanning directions into a plurality of areas A of pixels of 10×10 dots and the cumulative number of dots of black pixels (effective pixels) of exposure data of a plurality of pages in the divided areas is closely related to the amount and distribution state of the residual toner on the photoreceptor to obtain estimated values indicating the amount and distribution state of the residual toner. Since the cleaning device collects the residual toner in a plurality of divided areas corresponding to the plurality of divided areas, if even one of the plurality of areas has the number of effective pixels exceeding a given threshold, it is determined that the amount of the residual toner in the corresponding divided area of the cleaning device exceeds the permissible value and then the remaining toner is discharged. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as an electrophotographic image forming apparatus, for example, a copier, a printer, a facsimile, or a multifunction peripheral having the functions of these apparatuses, and an image forming method thereof.
[0002]
[Prior art]
2. Description of the Related Art In an electrophotographic image forming apparatus, for example, a laser printer, an image latent image is formed by projecting a laser beam modulated by an image signal onto a charged photoreceptor, and the image latent image is developed with toner. Form a toner image. Further, the toner image formed on the photoreceptor is transferred to a recording medium, and the transferred toner image is subjected to a fixing process to record an image on the recording medium.
[0003]
In a transfer process for transferring a toner image formed on a photoconductor to a recording medium, the toner image is not completely transferred to the recording medium, and a part of the toner remains on the photoconductor. Since the residual toner on the photoreceptor degrades the image quality, the image forming apparatus is provided with a cleaning device that approaches or contacts the photoreceptor, removes and collects the residual toner, and develops the collected toner again. Some are configured to return to the device.
[0004]
There are various types of cleaning devices that remove and collect such residual toner. For example, a cleaning device that uses a cleaning roller that comes into contact with a photoreceptor removes the residual toner on the photoreceptor by electrostatic force. It is configured to be adsorbed on and removed.
[0005]
If the toner adsorbed on the cleaning roller is left as it is, the cleaning function of the cleaning roller gradually deteriorates and the image quality deteriorates. There is a configuration in which the suction toner is discharged from the cleaning roller when it is estimated that the toner has reached, and the discharged toner is returned to the developing device again (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-2001-34134.
[0007]
In the above publication, in estimating the amount of toner adsorbed on the cleaning roller, the amount of image data for recording an image latent image on the photoconductor is detected and the accumulated value of the amount of image data for a plurality of pages is obtained. There has been proposed a configuration in which when the accumulated value reaches a predetermined limit value, it is estimated that the amount of attracted toner has reached an allowable limit amount, a cleaning process is executed, and the toner adsorbed on the cleaning roller is discharged.
[0008]
Further, depending on the toner image formed on the photoreceptor, a large amount of toner adheres to a specific area, for example, an area of a ruled line in image recording including a ruled line, and a small amount of toner adheres to other areas. For this reason, after transferring the formed toner image to the recording medium, if the toner remaining on the photoreceptor is attracted to the cleaning roller, the amount of the attracted toner is particularly large at the position corresponding to the ruled line portion of the cleaning roller, There is an inconvenience that the cleaning function is reduced only in this portion.
[0009]
For this reason, in the above publication, the projection position of the laser beam for recording the image latent image on the photoreceptor is slightly shifted in the main scanning direction every time one page of image exposure is performed. A configuration has been proposed in which even in the case of image recording, the toner is prevented from being intensively attached to the area of the ruled line portion, and the residual toner is not intensively attracted to a specific position in the axial direction of the cleaning roller in the cleaning process. ing.
[0010]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, in the configuration in which the amount of residual toner adsorbed is estimated based on the accumulated value of the image data amount, the total amount of residual toner adsorbed on the cleaning roller can be estimated. , And which portion in the radial direction the residual toner adsorption amount is large or small cannot be known.
[0011]
In a configuration in which the projection position of the laser beam is slightly shifted in the main scanning direction for each image exposure of one page, the possibility that the residual toner is intensively adsorbed to a specific position in the axial direction of the cleaning roller is small. It is not possible to know in which portion of the cleaning roller in the axial direction and in the radial direction the amount of adsorbed residual toner is large or small.
[0012]
As described above, in the conventional configuration, it is not possible to know the amount of residual toner adsorbed in each part of the cleaning device in the axial direction and the radial direction. Even if the amount exceeds the allowable limit and the cleaning function of the cleaning device deteriorates, the cleaning device continues to be used, and the residual toner on the photoreceptor cannot be sufficiently removed, so that the image quality may be deteriorated.
[0013]
Further, the configuration in which the projection position of the laser beam is slightly shifted in the main scanning direction for each image exposure of one page not only complicates the exposure control but also enlarges the print recording width and increases the size of the apparatus itself. There were inconveniences. An object of the present invention is to solve the above problems.
[0014]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems, and the invention of claim 1 provides an image carrier, and forms an image latent image on the image carrier based on image information and develops the image latent image. Image forming means for transferring the obtained image to a recording medium, and rotating about a rotation axis extending in the main scanning direction of the image carrier, and contacting the image carrier to copy the image on the image carrier to the recording medium. Contact means for collecting a residue remaining on the image carrier after being transferred to the image carrier, based on a distribution state of the image information amount used for forming the image latent image on the image carrier. A residue estimating unit for estimating at least a residual amount of the residue collected in the contact unit in the rotation axis direction of the contact unit and a distribution state thereof, and applying a voltage applied to the contact unit to a first unit. Control means for switching between a voltage and a second voltage; The stage applies a first voltage to the contact unit based on the information indicating the amount of the collected residue estimated by the residue estimation unit and the distribution state of the residue and applies the residue on the image carrier to the contact unit. The image forming apparatus is characterized in that the applied voltage is switch-controlled so as to collect and apply a second voltage to the contact means so that the residue collected by the contact means is re-emitted onto the image carrier. .
[0015]
The residue estimating means estimates a residue recovery amount and a distribution state in the rotation axis direction of the contact means, and a residue and a distribution state in a direction intersecting with the rotation axis direction of the contact means. May be used as residue estimation means.
[0016]
Further, the residue estimation unit divides the image area on the image carrier into a plurality of areas along the main scanning direction and the sub-scanning direction, and calculates the pixels constituting the image on each of the divided image areas. Residue estimation means for estimating the amount of residue collected and its distribution based on the number.
[0017]
Further, the contact means may be any one of a cleaning member for cleaning the surface of the image carrier, a charging member for applying a charge to the image carrier, and a transfer member for transferring an image formed on the surface of the image carrier to a recording medium. can do.
[0018]
The invention according to claim 5, wherein an image carrier, an image latent image is formed on the image carrier based on image information, and an image obtained by developing the image latent image is transferred to a recording medium. Means for rotating about an axis of rotation of the image carrier extending in the main scanning direction, contacting the image carrier, transferring the image on the image carrier to a recording medium, and remaining on the image carrier. Contact means for collecting the residue; applying a first voltage to the contact means to collect the residue on the image carrier in the contact means; applying a second voltage to the contact means to contact the contact means; An image forming method in an image forming apparatus for re-discharging a residue collected by means on an image carrier, comprising the following steps:
Estimating the amount of the residue collected by the contact unit and the distribution thereof based on the distribution of the image information amount used for forming the image latent image on the image carrier;
A step of switching a voltage applied to the contact means from a first voltage to a second voltage based on the estimated residue and its distribution state.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a diagram schematically illustrating the configuration of an electrophotographic image forming apparatus 10 suitable for carrying out the present invention. In FIG. 1, reference numeral 11 denotes a photoreceptor constituting an image carrier having a photosensitive layer formed on the surface, around which a charging device 12 constituting an image forming means, an exposure device 13 having a laser device, and a developing device 14, a transfer device 15, a cleaning device 16 constituting a contact unit, and an eraser 17 are arranged. In addition, the image forming apparatus 10 includes a paper feeding device 20 for feeding the recording medium P, a timing roller 19, a fixing device 18, and the like. The black circles on the surfaces of the photoconductor 11, the cleaning device 16, and the like indicate toner.
[0020]
Although the configuration of the above-described electrophotographic image forming apparatus 10 is known, its configuration and operation will be briefly described. First, when the power is turned on, the photoconductor 11 is continuously rotated in the direction of arrow a by a driving device (not shown). The charging device 12 is operated to uniformly apply a charge to the photosensitive layer on the surface of the photoreceptor 11 to be charged. A laser beam modulated by an image signal from the laser device of the exposure device 13 is projected on the surface of the photoconductor 11 to form an electrostatic latent image.
[0021]
When the electrostatic latent image formed on the surface of the photoconductor 11 comes to the position of the developing device 14 due to the rotation of the photoconductor 11 in the direction of the arrow a, the electrostatic latent image is developed by the toner loaded in the developing device 14. An image is formed by the toner on the surface of.
[0022]
The image (toner image) formed on the surface of the photoconductor 11 is fed from the paper feeding device 20 at the timing of coming to the transfer position by the rotation of the photoconductor 11 in the direction of arrow a, and temporarily stopped at the timing roller 19. The recording medium P is transported to the transfer position by the rotation of the timing roller 19, and the image (toner image) on the surface of the photoconductor 11 is transferred to the recording medium P by the operation of the transfer device 15.
[0023]
Thereafter, the recording medium P to which the image (toner image) has been transferred is conveyed to the fixing device 18 and subjected to heat fixing processing, and is fixed to the recording medium P. The toner remaining on the photoconductor 11 is removed by a cleaning device 16 as described later in detail, and the residual charge on the photoconductor 11 is removed by an eraser 17.
[0024]
In the above-described image forming process, the toner image on the surface of the photoconductor 11 is transferred to the recording medium P, but a part of the toner image remains on the photoconductor 11 without being transferred. Since the residual toner on the photoconductor degrades image quality, a cleaning device 16 for removing the residual toner is arranged in contact with the photoconductor 11.
[0025]
In the following description, the cleaning device that forms the contact unit will be described as an example in which the cleaning device is configured by a cleaning roller, and thus the cleaning device will be described as the cleaning roller 16.
[0026]
A voltage having a polarity opposite to the polarity of the charged toner is applied to the cleaning roller 16, and the cleaning roller 16 attracts residual toner that is a residue remaining on the surface of the photoconductor 11. For example, when the charge polarity of the toner is negative, a positive voltage is applied to the cleaning roller 16.
[0027]
When the suction of the residual toner by the cleaning roller 16 is repeated, the adsorbed toner gradually accumulates on the cleaning roller 16 and the cleaning function is reduced, thereby deteriorating the image quality. Therefore, it is necessary to perform a process of discharging the toner accumulated from the cleaning roller 16. There is. Therefore, in this embodiment, when the image forming operation is repeated and the estimated value of the amount of toner deposited on the cleaning roller 16 reaches a predetermined allowable limit, the cleaning mode is set and the cleaning operation is started. In the following description, the cleaning operation refers to a process of discharging the toner accumulated on the cleaning roller 16 onto the photoconductor 11.
[0028]
In the cleaning operation, since the cleaning roller 16 has a high potential voltage having the same polarity as the charged polarity of the toner, that is, the surface potential of the photoconductor 11 is a minus potential, the cleaning roller 16 has a higher potential than the surface potential of the photoconductor 11. By applying a negative potential having a high absolute value, the negative polarity toner deposited on the cleaning roller 16 is discharged onto the surface of the photoconductor 11. At this time, a voltage having the same polarity as that of the toner is applied to the transfer device 15 to prevent the released toner from adhering to the transfer device 15.
[0029]
In the cleaning operation, a positive potential is applied to the developing roller of the developing device 14 so that the toner discharged on the surface of the photoconductor 11 is attracted to the developing roller and collected by the developing device 14.
[0030]
Next, estimation of the accumulated value of the amount of toner deposited on the cleaning roller 16 will be described. The amount of toner adsorbed on the cleaning roller 16 is closely related to the amount of toner consumed for image formation, and the amount of toner consumed for image formation is closely related to the amount of exposure data for forming a toner image on the photoconductor 11. Is based on the finding that the accumulated amount of the residual toner amount can be estimated from the accumulated value of the exposure data.
[0031]
FIG. 2 is a view for explaining one page of exposure data formed on the surface of the photoconductor 11, in which an image area on the photoconductor 11 is divided into a plurality of areas A along a main scanning direction and a sub-scanning direction. The size of each divided area A is an area composed of 10 dots × 10 dots and having 100 pixels. The description that each of the divided areas A is 100 dots composed of pixels of 10 dots × 10 dots is merely an example, and the present invention is not limited to this. It goes without saying that the size of each divided area A can be arbitrarily determined accordingly.
[0032]
The number written in each divided area A is the number of dots of black pixels in the divided area of the exposure data for one page (in the case of binary black and white, the black pixels are hereinafter referred to as “effective pixels”). Is an example of an accumulated value obtained by accumulating a plurality of pages, and shows an accumulated value in which 100 dots are set as one unit. That is, the numerical value 2 in the divided area a1 at the upper left of FIG. 2 indicates that the cumulative value of the number of dots of the effective pixels in this divided area is 200, that is, 200 dots.
[0033]
Exposure data and the amount of toner adhering to the photoconductor 11 are substantially proportional to each other, and are also closely related to the amount of toner adhering to the photoconductor 11 and the amount of residual toner remaining on the photoconductor 11 after transfer of the toner image. When the amount of toner adhering to the photoconductor 11 is large, the amount of residual toner remaining on the photoconductor 11 after transfer also increases.
[0034]
Accordingly, the cumulative value of the number of dots of the effective pixels and the distribution state in the main scanning direction and the sub scanning direction of the exposure data of each divided area on the photoconductor 11 shown in FIG. Not only are the parameters indicating the cumulative amount and the distribution state, but also the parameters indicating the cumulative amount and the distribution state of the toner amount remaining on the photoconductor 11 after the transfer of the toner image.
[0035]
On the other hand, in this embodiment, the amount of the residual toner adsorbed and accumulated on the cleaning roller 16 is finely estimated in the axial direction (rotation axis direction) and the circumferential direction (direction intersecting the axial direction) of the cleaning roller 16. Then, when the residual toner amount exceeds the limit value, the cleaning process of the cleaning roller 16 is executed. For this reason, the surface of the cleaning roller 16 is also divided in the axial direction and the circumferential direction. The divided area of the cleaning roller 16 is referred to as a divided area.
[0036]
Therefore, among the data indicating the cumulative value of the number of dots of the effective pixels in each divided area and the data indicating the distribution state shown in FIG. Is the data indicating the toner adsorption amount and distribution state of each divided area in the axial direction (rotation axis direction), and the cumulative value and distribution state of the effective pixel dots of each divided area in the sub-scanning direction is the circumference of the cleaning roller 16. The toner adsorption amount and the distribution state of each divided area in the direction (direction intersecting the axial direction) will be handled as data indicating the distribution state.
[0037]
If the diameter of the cleaning roller 16 is the same as the diameter of the photoconductor 11 and the rotation speed is the same, each divided area in the axial direction and the circumferential direction of the cleaning roller becomes the same as that shown in FIG. The cleaning roller 16 also makes one rotation while the rotation of the cleaning roller 16 makes one rotation, and the residual toner corresponding to the main scanning direction and the sub-scanning direction area of the photoconductor 11 shown in FIG. Adsorbed to the area.
[0038]
However, when the diameter of the cleaning roller 16 is smaller than the diameter of the photoconductor 11, for example, 1/4 of the diameter of the photoconductor 11, the cleaning roller 16 rotates four times while the photoconductor 11 makes one rotation. In this case, each divided area in the axial direction of the cleaning roller is the same as that shown in FIG. 2, but each divided area in the circumferential direction of the cleaning roller is 1/4 of the one shown in FIG. 2, a1, a2, a3, a4, a5), and the amount of toner adsorbed in each of the circumferentially divided areas adsorbed on the cleaning roller 16 during one rotation of the photoconductor 11 is shown in FIG. Residual toner corresponding to each divided region obtained by dividing the direction region into four is superposed and adsorbed on the same divided region of the cleaning roller 16.
[0039]
That is, to explain each of the leftmost regions in the sub-scanning direction of the image region shown in FIG. 2, the leftmost region is divided into four from the top, and the first divided regions are a1, a2, a3, a4, and a5. , The area of the second section is b1, b2, b3, b4, b5, the area of the third section is c1, c2, c3, c4, c5, and the area of the fourth section is d1, d2, d3, d4, d5. The residual toner corresponding to the second section area b1, the third section area c1, and the fourth section area d1 is located in the first section area a1 in the circumferential direction of the cleaning roller 16 (the first section a1). ), The residual toner corresponding to the second section area b2, the third section area c2, and the fourth section area d2 is the same in the circumferential direction of the cleaning roller 16 in the first section area a2. Superimposed on divided area (second area a2) It is adsorbed Te. The same applies to the other areas.
[0040]
When image formation for a plurality of pages is performed, residual toner corresponding to each of the divided regions of the photoconductor 11 for the plurality of pages in the main scanning direction and the sub-scanning direction is the same in the axial direction and the circumferential direction of the cleaning roller 16. It will be superimposed and adsorbed on the area.
[0041]
In the above description, in order to facilitate understanding, the case where the diameter of the cleaning roller is 1/4 of the diameter of the photoconductor 11 is taken as an example, and the residual toner corresponding to each divided area of the photoconductor 11 in the sub-scanning direction is reduced. It has been described that the cleaning roller 16 is attracted by being superimposed on the same divided area in the circumferential direction. However, depending on the ratio between the diameter of the photoconductor and the diameter of the cleaning roller, each divided area in the sub-scanning direction of the image area does not correspond to the same divided area on the cleaning roller in the circumferential direction, and a plurality of pages are not included. In the image formation described above, there may be cases where each divided area of the photoconductor 11 in the sub-scanning direction does not correspond to the same divided area of the cleaning roller 16 in the circumferential direction.
[0042]
However, even when such divided regions in the sub-scanning direction of the image region do not correspond to the same divided regions in the circumferential direction on the cleaning roller, at least each divided region in the main scanning direction of the photoconductor 11 corresponds to each divided region. Obviously, the accumulated value obtained by accumulating the number of dots of the corresponding pixel for a plurality of pages represents the accumulated amount of the residual toner amount adsorbed to any one of the same divided areas in the axial direction of the cleaning roller 16.
[0043]
In the sub-scanning direction of the photoconductor 11, the accumulated value obtained by accumulating the number of dots of pixels corresponding to each divided area of the photoconductor 11 for a plurality of pages is determined by the ratio of the diameter of the photoconductor to the diameter of the cleaning roller. Even if the cumulative amount of the residual toner adsorbed on the same divided area in the circumferential direction of the roller 16 does not accurately correspond to the total amount of the accumulated values of the divided areas in the circumferential direction, the sum of the accumulated values of the divided areas in the circumferential direction of the cleaning roller 16 is Represents the accumulated amount of the residual toner amount adsorbed on any of the above.
[0044]
If the accumulated amount of the residual toner adsorbed in each of the divided areas in the axial direction and the circumferential direction of the cleaning roller 16 is accurately known, as described above, the diameter of the cleaning roller and the diameter of the photoconductor are determined as described above. May be appropriately set, for example, set to 1: 4.
[0045]
Therefore, in this embodiment, a cumulative value obtained by accumulating the number of dots of effective pixels in each divided area in the main scanning direction and the sub-scanning direction of one page of exposure data formed on the surface of the photoconductor 11 for a plurality of pages. , The accumulated amount of the residual toner amount adsorbed to each of the divided areas in the axial direction and the circumferential direction of the cleaning roller 16 is estimated. The cleaning mode is set when the estimated accumulated amount of the residual toner in at least one of the divided areas in the axial direction and the circumferential direction of the cleaning roller 16 reaches a predetermined allowable limit. Start to work.
[0046]
Next, the control device 21 that controls the image forming apparatus 10 will be described. FIG. 3 is a block diagram illustrating the configuration of the control device 21. The control device 21 is mainly configured with a CPU 22. Input / output ports of the CPU include an I / F controller 23, an image memory 24, a RAM 25, a ROM 26, a switch / sensor controller 27, an exposure controller 31, an exposure data integration calculator 32, a charging controller 33, and a development controller. 34, a transfer control unit 35, a cleaning control unit 36, a main motor, a fixing device, an eraser, a paper feeding mechanism, a timing roller, and other various devices 45 (here, reference numeral 45 represents other devices). 37 is connected.
[0047]
The I / F control unit 23 controls transmission and reception of image signals transferred from the external device 41, for example, a personal computer or the like. The image memory 24 is a memory for storing and editing received image signals, and the RAM 25 is used for integrating the dot number of pixels of exposure data, which will be described later, and for storing the integrated value and the accumulated value for a plurality of pages. The first and second memories and other memories for temporarily storing data for arithmetic processing. The ROM 26 is a memory for storing control programs and the like.
[0048]
The switch / sensor control unit 27 controls various keys for inputting instructions from the operator to the image forming apparatus 10, various sensors, a display unit 46 (represented by reference numeral 46 here), and the like.
[0049]
The exposure control unit 31 controls the exposure device 13 including the laser light emitting device, and controls the modulation of the laser beam by the exposure data that has been edited and the projection of the laser beam onto the photoconductor 11.
[0050]
The exposure data integration calculating section 32 performs, on the basis of the exposure data used for modulating the laser light in the exposure control section 31, each of the divided data arranged in the main scanning direction and the sub-scanning direction described above with reference to FIG. The number of effective pixels in each area (10 dots × 10 dots) is integrated, and the number of effective pixels is cumulatively calculated for exposure data for a plurality of pages.
[0051]
In this embodiment, when the cumulative value of the number of dots of the effective pixel of each divided area, which is cumulatively calculated by the exposure data integration calculating unit 32, exceeds a preset threshold value in any one of the divided areas. Then, it is estimated that the residual toner collected in the divided area of the cleaning roller 16 corresponding to the divided area exceeds the allowable value, and the operation mode of the image forming apparatus is switched from the print mode to the cleaning mode.
[0052]
The charging control unit 33 controls the charging device 12 to uniformly charge the surface potential of the photoconductor 11 to a potential suitable for image formation.
[0053]
The development control unit 34 controls the developing device 14. When the operation mode is the print mode, the development control unit 34 controls the voltage applied to the development roller to a value suitable for development, and controls the electrostatic force formed on the surface of the photoconductor 11. The latent image is developed with toner. When the operation mode is switched to the cleaning mode, the voltage applied to the developing roller is controlled to a value suitable for collecting the toner, and the toner discharged onto the photoconductor 11 is collected in the developing device 14.
[0054]
When the operation mode is the print mode, the transfer control unit 35 controls the voltage applied to the transfer device 15 to a value suitable for transfer, and records the toner image formed on the surface of the photoconductor 11. Transfer to a medium. When the operation mode is switched to the cleaning mode, the voltage applied to the transfer device 15 is controlled to the value of the cleaning mode, and the toner discharged onto the photoconductor 11 is controlled so as not to be attracted to the transfer device 15.
[0055]
The cleaning controller 36 controls the cleaning roller 16. When the operation mode is the print mode, the cleaning controller 16 applies a first voltage to the cleaning roller 16, which is a voltage suitable for attracting toner remaining on the surface of the photoconductor 11. When the operation mode is switched to the cleaning mode, the potential of the cleaning roller 16 is switched to and applied to the second voltage that is higher than the absolute value of the potential of the photoconductor 11, and the adsorbed toner is removed. It is discharged to the photoconductor 11.
[0056]
The other control unit 37 controls the fixing device 18, the eraser 17, the sheet feeding device 20, the timing roller 19, and other various devices 45 such as a main motor (not shown).
[0057]
Although not shown, the image forming apparatus is provided with a power supply unit, and a charging control unit 33, a charging control unit 33, a developing roller of the developing device 14, a transfer device 15, and a cleaning roller 16, respectively. It is assumed that the predetermined voltage is supplied through the respective control units of the development control unit 34, the transfer control unit 35, and the cleaning control unit 36.
[0058]
FIGS. 4 and 5 are flowcharts illustrating the estimation of the accumulated amount of the residual toner adsorbed on the cleaning roller 16 and the cleaning process of the cleaning roller 16 in the control operation of the image forming apparatus performed by the control device 21. is there.
[0059]
First, the outline of the estimation of the accumulated amount of the residual toner amount and the cleaning process of the cleaning roller 16 will be described with reference to the flowchart of FIG. At the start of the normal operation, the print mode is set as the operation mode (the cleaning mode is released), and the first and second memories are cleared (steps P1 and P2). The exposure data is read, the exposure data for one page to be printed is edited, the edited exposure data is output to the exposure device 13, and the printing operation is executed (steps P3 and P4). In the printing operation, as a matter of course, cleaning of the residual toner on the surface of the photoconductor 11 by the cleaning roller 16 (adsorption of the residual toner to the cleaning roller) is also performed.
[0060]
The edited exposure data for one page is fetched, the number of dots of effective pixels of the exposure data is integrated for each divided area (see FIG. 2), and the integrated value for each divided area corresponds to each area of the first memory. It is stored in the storage area (step P5).
[0061]
From the second memory that stores the accumulated value of the accumulated number of dots of the effective pixels for each divided area for a plurality of pages, the accumulated value of the number of dots of the effective pixels for each divided area (initially zero) is read. The cumulative value is calculated by adding the integrated value of the number of dots of the effective pixel for each divided region stored in one memory, and the calculated cumulative value for each divided region is stored in the second memory (step P6). .
[0062]
It is determined whether or not the cumulative value of the number of dots of the effective pixels of each image area stored in the second memory has exceeded a preset threshold (step P7). It is estimated that the residual toner collected in the area corresponding to each image area of the cleaning roller 16 has exceeded the allowable value, the operation mode of the image forming apparatus is switched from the print mode to the cleaning mode and set, and the print mode is set. Release (step P8).
[0063]
The cleaning process of the cleaning roller 16 is performed (Step P9). When the cleaning process is completed, the operation mode is set to the print mode again, and the cleaning mode is released (Step P10).
[0064]
It is determined whether or not there is a next page to be printed (step P11). If there is a next page, the process proceeds to step P3 to start image editing of a new one page. If it is determined in step P11 that there is no next page to be printed, a print end process is performed (step P12), and all processes are ended.
[0065]
Next, the details of the cleaning process of the cleaning roller 16 shown as Step P9 in the flowchart of FIG. 4 will be described with reference to the flowchart of FIG. First, predetermined time data is set in a timer for counting the time of the cleaning process, and time counting is started (step P21). The predetermined time data set in the timer is a value determined in advance by an experiment or the like.
[0066]
The voltage applied to the cleaning roller 16, the voltage applied to the transfer device 15, and the voltage applied to the developing roller of the developing device 14 are set to voltage values suitable for the cleaning process (Step P <b> 22). 11 (step P23). Waiting for the elapse of the time set for the cleaning process (step P24), and when the set time has elapsed, the cleaning process has been completed, so the contents of the first and second memories are cleared (step P25). The voltage applied to the cleaning roller 16, the voltage applied to the transfer device 15, and the voltage applied to the developing roller of the developing device 14 are set to voltage values suitable for print processing (step P26), and the process returns to the main routine.
[0067]
In the embodiment of the present invention described above, a cleaning roller is used as a cleaning device. However, a cleaning brush, a cleaning belt, a cleaning magnetic brush, or the like may be used as the cleaning device in addition to the cleaning roller. .
[0068]
Further, when the charging device is constituted by a charging brush, the charging brush can be used as a cleaning roller when the cleaning mode is set. In this case, it goes without saying that the voltage applied to the charging brush is set to a voltage suitable for the cleaning process.
[0069]
Further, in the embodiment of the present invention, the developing device is configured to collect the residual toner discharged on the photoconductor, but the residual toner discharged on the photoconductor is disposed close to the photoconductor. You may comprise so that it may collect | recover with an exclusive collection device.
[0070]
In an image forming apparatus including a plurality of photoconductors, such as a tandem-type color image forming apparatus, a cleaning device is disposed on each of the plurality of photoconductors, and a cleaning device is disposed on a transfer belt. However, in this case, when it is determined in any one of the cleaning devices that the cumulative value of the number of dots of the effective pixels in each of the divided areas described above exceeds a predetermined threshold, the cleaning mode is set and the cleaning process is performed. It is good to do it.
[0071]
Further, in the embodiment of the present invention, the cumulative amount of the residual toner amount is estimated from the cumulative value of the exposure data for one page formed on the surface of the photoconductor. Here, the exposure data includes not only print (including an image) data input from an external device, for example, a personal computer or the like, but also a video signal and the like.
[0072]
To estimate the accumulated amount of the residual toner, the image area on the photoconductor 11 is divided into a plurality of areas A along the main scanning direction and the sub-scanning direction, and the number of dots of black pixels in each area is calculated. Although the accumulated value accumulated for a plurality of pages is used, the accumulated value of the laser emission amount for each area can be used instead of the accumulated value of the number of dots.
[0073]
The above embodiments include inventions having the following configurations.
[0074]
(1) In the first aspect of the present invention, the image formed on the image carrier includes a toner image, and the residue remaining on the image carrier includes residual toner.
[0075]
(2) The power supply apparatus according to claim 1, further comprising a power supply apparatus for outputting the first and second voltages, wherein the control unit is configured to control the power supply apparatus based on information indicating the estimated amount of the collected residue and its distribution state. The first and second voltages output from the switch are switched and supplied to the contact means.
[0076]
【The invention's effect】
As described above, according to the image forming apparatus and the image forming method of the present invention, the residue formed on the image carrier after the image formed on the image carrier is transferred onto the recording medium is removed by the contact means (such as a cleaning device). ), The amount and distribution of the residue collected by the contacting means are estimated based on the image information for forming an image on the image carrier, and a part of the contacting means is estimated based on the estimation result. When it is estimated that a residue exceeding the allowable value even partially is collected, the contact unit expels the collected residue onto the image carrier.
[0077]
As a result, in a conventional image forming apparatus, in the case of forming an image of a special pattern such as an image having a large number of ruled lines, even if a residue exceeding a permissible value is collected in a part of the contact means, the fact cannot be known. However, according to the present invention, the cleaning operation is performed at an appropriate time by estimating the collection amount and distribution state of the residue collected by the contact unit. Thus, it is possible to prevent a decrease in image quality.
[0078]
In addition, since the residue remaining on the image carrier can be collected at an appropriate time, the cleaning operation is not performed unnecessarily frequently, and the image forming operation can be performed efficiently.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating the configuration of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a view for explaining exposure data for one page formed on the surface of a photoconductor.
FIG. 3 is a block diagram illustrating a configuration of a control device.
FIG. 4 is a flowchart illustrating an outline of an estimation of an accumulated amount of a residual toner amount and a cleaning process in a control operation of the image forming apparatus performed by the control device.
FIG. 5 is a flowchart illustrating details of a cleaning process.
[Explanation of symbols]
10 Image forming apparatus
11 Photoconductor
12 Charging device
13 Exposure equipment
14 Developing device
15 Transfer device
16 Cleaning device (cleaning roller)
17 Eraser
18 Fixing device
19 Timing Roller
20 Paper feeder
21 Control device
22 CPU
23 I / F control unit
24 Image memory
25 RAM
26 ROM
27 Switch / sensor control unit
31 Exposure controller
32 Exposure data integration calculator
33 Charge control unit
34 Development Control Unit
35 Transfer control unit
36 Cleaning control unit
37 Other control units
41 External device (PC)
45 Other equipment
46 Various keys and sensors

Claims (5)

An image carrier;
Image forming means for forming an image latent image on the image carrier based on image information, and transferring an image obtained by developing the image latent image to a recording medium;
The image carrier rotates around a rotation axis extending in the main scanning direction, and contacts the image carrier to transfer an image on the image carrier to a recording medium. An image forming apparatus comprising:
Based on the distribution of the amount of image information used to form the image latent image on the image carrier, of the residues collected by the contact unit, at least the amount of the residue collected in the rotation axis direction of the contact unit and its Residue estimation means for estimating a distribution state;
Control means for switching an applied voltage applied to the contact means between a first voltage and a second voltage,
The control unit applies a first voltage to the contact unit based on the information indicating the amount of the collected residue and the distribution state estimated by the residue estimation unit to contact the residue on the image carrier. An image forming apparatus, wherein an applied voltage is switched and controlled so that a second voltage is applied to the contact means and a residue collected by the contact means is re-emitted onto the image carrier. . The residue estimating means estimates a residue recovery amount in the rotation axis direction of the contact means and its distribution state, and a residue in a direction intersecting with the rotation axis direction of the contact means and its distribution state. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is an object estimating unit. The residue estimation unit divides the image area on the image carrier into a plurality of areas along the main scanning direction and the sub-scanning direction, and calculates the number of pixels constituting an image on each of the divided image areas. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a residue estimating means for estimating a collected amount of the residue and a distribution state thereof based on the residue. The contact unit may be any one of a cleaning member for cleaning the surface of the image carrier, a charging member for applying a charge to the image carrier, and a transfer member for transferring a toner image formed on the surface of the image carrier to a recording medium. The image forming apparatus according to claim 1, wherein: An image carrier, an image forming unit that forms an image latent image on the image carrier based on image information, and transfers an image obtained by developing the image latent image to a recording medium; and the image carrier. Contact means for rotating around a rotation axis extending in the main scanning direction of the image carrier, contacting the image carrier, transferring an image on the image carrier to a recording medium, and recovering a residue remaining on the image carrier after being transferred to a recording medium. A first voltage is applied to the contact means to collect a residue on the image carrier to the contact means, and a second voltage is applied to the contact means to collect the residue to the contact means. The image forming method in the image forming apparatus for re-emission of the image on the image carrier includes the following steps:
Estimating the amount of the residue collected by the contact unit and the distribution thereof based on the distribution of the image information amount used for forming the image latent image on the image carrier;
A step of switching a voltage applied to the contact means from a first voltage to a second voltage based on the estimated residue and its distribution state.

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