JP2010032832A - Rotation control method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain a charge property without degrading developability of toner on a developing roller by controlling rotation of the developing roller, and to maintain an excellent image formation over a long term by preventing the toner from sticking to a regulating member. <P>SOLUTION: A rotation control method for an image forming apparatus having a photoreceptor drum 2 carrying a latent image and driven to rotate, a latent image forming means for forming a latent image by exposing the photoreceptor drum by an exposure means, and the developing roller 103 for developing the latent image on the photoreceptor drum 2 with the toner and driven to rotate includes a developing amount analysis means. Developing amount analysis is performed in predetermined timing during image forming operation by the developing amount analysis means. By controlling the rotation of the developing roller in accordance with a result of the analysis, the charge property is maintained without lowering the developability of the toner on the developing roller, and the toner is prevented from sticking to a toner layer regulating member 104. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus used as a copying machine, a printer, a plotter, a facsimile, or a composite machine thereof, and more particularly to a toner carrier rotation control method and its rotation control method in the image forming apparatus. The present invention relates to the image forming apparatus used.

When an electrophotographic image forming apparatus uses a one-component developing method, a regulating member (for example, a regulating blade) is generally brought into contact with the developing roller, which is a toner carrier, in order to form a thin toner layer. Is.
In this system, the toner is pressed against the developing roller by the regulating member, and the toner is charged mainly by frictional charging with the developing roller.
At this time, the toner is pressed against the regulating member in the same manner as the pressure contact with the developing roller. For this reason, a phenomenon occurs in which the toner adheres to the regulating member and appears as white streaks on the image. In particular, when a bias having the same polarity as that of the toner is applied to the regulating member, toner having a polarity opposite to the normal polarity and weakly charged toner having a small charge amount are easily fixed to the regulating member.

  Therefore, in order to prevent toner from adhering to the regulating member, for example, Japanese Patent Application Laid-Open No. 8-254894 discloses that in a developing device, a blade-type toner regulating member is brought into contact with the developing sleeve and the developing sleeve is used. Discloses a technique for providing a member (reversely charged toner collecting roller) other than the regulating member that contacts the developing sleeve on the downstream side of the toner regulating member.

JP-A-8-254894

In the prior art described in Patent Document 1, a blade-type toner regulating member is brought into contact with the developing sleeve, and a roller member (reversely charged toner collection) is positioned downstream of the developing sleeve and upstream of the developing region. Roller).
The toner regulating member and the roller member are applied with a bias having the same polarity as the polarity of the toner with respect to the developing sleeve.

  However, when the thin layer once formed with the toner regulating member on the toner carrying member such as the developing sleeve is further pressed by the contact member such as the roller member, the adhesion force between the toner carrying member and the toner, and the toner The adhesion force between the toner and the toner increases, and even if a sufficient electric field is applied between the latent image carrier and the toner carrier, it becomes difficult to sufficiently develop the toner, so that a sufficient image density can be obtained. There is a problem that it becomes difficult.

  The present invention has been made in view of the above circumstances, can maintain the chargeability without deteriorating the developability of the toner on the toner carrier, and prevents the toner from sticking to the regulating member. An object of the present invention is to provide a method for controlling the rotation of a toner carrier in an image forming apparatus capable of performing the same, and further to provide an image forming apparatus capable of maintaining good image formation for a long period of time using the rotation control method. With the goal.

In order to achieve the above object, the present invention employs the following solutions.
The first means of the present invention comprises a latent image carrier capable of rotating and carrying a latent image, a latent image forming means for exposing the latent image carrier with an exposure means to form a latent image, and the latent image carrier. A rotation control method in an image forming apparatus having a rotationally driven toner carrier that develops a latent image on an image carrier with toner, the image forming apparatus comprising a development amount analyzer and image formation by the development amount analyzer The development amount analysis is executed at a predetermined timing during the operation, and the rotation of the toner carrier is controlled according to the analysis result.
According to a second means of the present invention, in the rotation control method according to the first means, the development amount analyzing means causes the surface of the toner carrier to have a predetermined length in the main scanning direction of the exposure means. And a development amount in each of the divided areas is calculated, and a ratio of the development amount to a predetermined surface travel distance of the latent image carrier is calculated.
Further, according to a third means of the present invention, in the rotation control method according to the first means, the development amount analyzing means divides the print area of the recording medium into a predetermined length in the main scanning direction of the exposure means. And a means for calculating a development amount in each of the divided areas and calculating a ratio of the development amount to a predetermined surface travel distance of the latent image carrier.

According to a fourth means of the present invention, in the rotation control method according to any one of the first to third means, the development amount analysis is executed by the development amount analysis means to control the rotation of the toner carrier. The timing to perform is determined by the number of continuous prints.
According to a fifth means of the present invention, in the rotation control method according to any one of the first to fourth means, the development amount is calculated from image data.
Furthermore, a sixth means of the present invention is characterized in that, in the rotation control method according to any one of the first to fifth means, the development amount is calculated from exposure information.
Furthermore, a seventh means of the present invention is the rotation control method according to any one of the first to sixth aspects, wherein the rotation control of the toner carrier is performed at a timing different from a normal image forming sequence. Features.
Further, according to an eighth means of the present invention, in the rotation control method according to any one of the first to seventh means, the rotation control of the toner carrying member is performed at the latent position at a plurality of divided positions in the main scanning direction. When the maximum value of the ratio of the development amount to the predetermined surface travel distance of the image carrier is greater than or equal to a predetermined value, the toner carrier is rotated for a predetermined time in addition to the normal sequence. Is characterized in that it is determined that the normal sequence is maintained.

According to a ninth means of the present invention, in the rotation control method according to any one of the first to eighth means, the rotation control of the toner carrier is executed at a plurality of timings.
According to a tenth means of the present invention, in the rotation control method of the ninth means, the set value of the ratio serving as a judgment reference decreases as the number of times of rotation control timing of the toner carrier increases. Features.
Further, an eleventh means of the present invention is the rotation control method according to the ninth or tenth means, wherein the ratio is equal to or greater than a predetermined value as the number of times of rotation control of the toner carrier increases. The set value of the time for rotating the toner carrying member becomes longer.
Further, a twelfth means of the present invention is the rotation control method according to any one of the ninth to eleventh means, wherein the rotation of the toner carrier is executed according to the development amount analysis result. The development amount analysis timing is reset even when all print jobs are not completed.

  A thirteenth means of the present invention comprises a latent image carrier that can be driven to carry a latent image, a latent image forming unit that exposes the latent image carrier with an exposure unit to form a latent image, and the latent image carrier. In the image forming apparatus having a toner carrier capable of rotationally developing the latent image on the image carrier with toner, any one of the first to twelfth means is used as means for controlling the rotation of the toner carrier. The rotation control method described in one is used.

  In the toner carrier rotation control method in the image forming apparatus of the present invention, the image forming apparatus has a developing amount analyzing unit, and the developing amount analyzing unit executes the developing amount analysis at a predetermined timing during the image forming operation, and the analysis result Accordingly, by controlling the rotation of the toner carrier, the chargeability can be maintained without degrading the developability of the toner on the toner carrier, and the occurrence of toner sticking to the regulating member can be prevented. be able to. In the image forming apparatus of the present invention, good image formation can be maintained for a long time by using the above rotation control method.

Hereinafter, specific configurations, operations, and actions of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating an embodiment of the present invention, and is a schematic cross-sectional view illustrating a main configuration of a tandem type image forming apparatus including a plurality of image forming units.
The image forming apparatus includes four image forming units 1Y, 1M, 1C, and 1K having different development colors (for example, yellow (Y), magenta (M), cyan (C), and black (K)). The image forming unit is a process cartridge having the same configuration.
Each of the process cartridges 1Y, 1M, 1C, and 1K has a configuration in which the photosensitive drum 2, the charging roller 3, the developing unit 4, and the cleaning unit 5 are integrally provided in one cartridge. Each of the process cartridges 1Y, 1M, 1C, and 1K is detachably mounted on the main body of the image forming apparatus, and can be replaced by releasing each stopper.

The photosensitive drums 2 in the process cartridges 1Y, 1M, 1C, and 1K are rotated at a peripheral speed of 150 mm / sec in the arrow direction in the figure.
The charging roller 3 as a charging unit is pressed against the surface of the photosensitive drum 2 and is driven to rotate by the rotation of the photosensitive drum 2.
A predetermined bias (DC bias or bias in which AC is superimposed on DC) is applied to the charging roller 3 by a high voltage power source (not shown), and the surface of the photosensitive drum 2 is charged to −500V.
The charging means is not limited to the charging roller, and a charging brush, a non-contact type charger, or the like may be used.

The exposure means 6 exposes the charged photoconductive drum 2 with a beam according to image information to form an electrostatic latent image, and constitutes a latent image forming means together with the charging means.
As this exposure means 6, for example, a light source (laser diode), a coupling optical system (an optical system comprising a coupling lens, an aperture, a cylindrical lens, etc.) and an optical deflector (for example, a polygon mirror (or a pyramid mirror, And an optical scanning device (laser beam scanner) including a scanning imaging optical system (constant speed scanning lens such as an fθ lens, an optical system including aberration and field curvature correction lens, a mirror, etc.) In addition to this, a line-shaped optical writing device in which a light emitting diode (LED) array and an imaging element array (such as a microlens array or a rod lens array) are combined may be used.
The scanning direction of the laser beam by the optical scanning device (laser beam scanner) and the writing direction of the linear optical writing device (direction parallel to the rotation axis of the photosensitive drum 2) are referred to as the main scanning direction. The rotation direction 2 is referred to as the sub-scanning direction.

  In this embodiment, the developing means 4 is a contact developing type developing device using a one-component developer (toner), and the electrostatic latent image on the photosensitive drum 2 is formed by toner carried on a developing roller as a toner carrying member. The image is developed and visualized as a toner image. A predetermined developing bias is supplied to the developing roller of the developing device 4 from a high voltage power source (not shown).

  The photoconductor cleaning means 5 is a cleaning device that removes residual toner on the surface of the photoconductor drum 2 with a cleaning member such as a cleaning blade or a fur brush, and performs cleaning.

  Each process cartridge 1Y, 1M, 1C, 1K has a moving direction (in the direction of an arrow in the figure) of a belt-shaped intermediate transfer body (intermediate transfer belt) 7 stretched around a plurality of rollers (a driving roller and a plurality of driven rollers). In each process cartridge 1Y, 1M, 1C, and 1K, charging by the charging roller 3, exposure by the exposure means 6, and development by the developing device 4 are performed. A visible image of each color is formed in the order of Y), magenta (M), cyan (C), and black (K).

  A primary transfer roller 8 is provided at a position facing the photosensitive drum 2 of each process cartridge 1Y, 1M, 1C, 1K on the back side of the intermediate transfer belt 7, and this primary transfer roller 8 is not shown. A predetermined primary transfer bias is applied from a high-voltage power source, and the toner images on the surfaces of the photosensitive drums 2 are sequentially superimposed and transferred onto the surface of the intermediate transfer belt 7. The intermediate transfer belt 7 is driven to rotate in the direction of the arrow in the drawing by a drive motor (not shown), and a full color image is formed by sequentially transferring the visible images of the respective colors onto the surface.

  A sheet feeding unit for supplying a transfer material is provided at the lower part of the image forming apparatus main body. The sheet feeding unit includes a plurality of sheet feeding cassettes 11A and 11B containing transfer sheets P having different sizes as recording media. The transfer paper P is fed one by one by the paper feed roller 12 and the separation roller 13 from the paper feed cassette 11A (or 11B) of the paper size selected by operating the operation panel (not shown), and the transport roller 14 and then conveyed to the registration roller 15. Then, the transfer paper P is fed to the nip portion between the intermediate transfer belt 7 and the secondary transfer roller 9 by the registration roller 15 in time with the primary transfer onto the intermediate transfer belt 7. The full color image formed on the intermediate transfer belt 7 is transferred to the transfer paper P by applying a predetermined secondary transfer bias to the secondary transfer roller 9 by a high voltage power source (not shown), and transferred to the transfer paper P. The full-color image is fixed by being heated and pressed at the nip portion of the heating roller 16a and the pressure roller 16b of the fixing device 16, and is output to a paper discharge tray (or post-processing device) not shown. The toner remaining on the intermediate transfer belt 7 without being transferred by the secondary transfer roller 9 is collected by the intermediate transfer belt cleaning means 10.

  The full-color image forming apparatus shown in FIG. 1 is provided with a control unit that controls driving of each unit described above and controls an image forming operation. Although not shown, the control unit includes, for example, a central processing unit (CPU) including a microprocessor unit, various memories (ROM, RAM, nonvolatile RAM, etc.), input / output devices (I / O ports, various interfaces, etc.) ), Various control circuits, a clock, a timer, a counter, and the like, and a control program and various data are stored in the memory in advance. Also, detection information from various sensors (temperature sensor, humidity sensor, density sensor, paper detection sensor, etc.) provided in each unit of the image forming apparatus is input to the control unit. Based on these information, Take control. Further, the control unit has a function as a development amount analysis unit, and the development amount analysis unit executes the development amount analysis at a predetermined timing during the image forming operation, and is a toner carrier according to the analysis result. Controls the rotation of the developing roller.

  Next, FIG. 2 is a diagram according to the embodiment of the present invention, and is a schematic sectional view showing a simplified sectional configuration of a process cartridge unit used in the image forming apparatus shown in FIG. 1, and FIG. FIG. 2 is a schematic cross-sectional view showing a main part of a developing device portion of the process cartridge unit shown.

  As shown in FIGS. 2 and 3, the developing device 4 includes a toner storage chamber 101 that stores toner T, and a toner supply chamber 102 provided below the toner storage chamber 101, and a lower portion of the toner supply chamber 102. Are provided with a developing roller 103 which is a toner carrier, a toner layer regulating member 104 and a supply roller 105 provided in contact with the developing roller 103. The developing roller 103 is disposed in contact with the photosensitive drum 2, and a predetermined developing bias is applied from a high voltage power source (not shown).

The surface of the supply roller 105 is covered with a foam material having a structure having pores (cells), and the toner T conveyed into the toner supply chamber 102 is attached and taken in efficiently, and the developing roller 103 and The toner is prevented from deteriorating due to pressure concentration at the contact portion.
The foamed material is set to an electric resistance value of 3 to 14 Ω. A DC voltage that is offset in the same direction as the charging polarity of the toner T with respect to the DC voltage applied to the developing roller 103 is applied to the supply roller 105. This voltage acts in a direction in which the toner preliminarily charged at the contact portion with the developing roller 103 is pressed against the developing roller 103. However, the direction of the offset is not limited to this, and depending on the type of the toner T, the offset may be 0 or the direction of the offset may be changed. Moreover, the applied voltage may superimpose an AC voltage on a DC voltage. The supply roller 105 is rotationally driven so as to move in the direction opposite to the surface movement direction of the developing roller 103 at a position facing the developing roller 103, and the developing roller that has passed through the contact portion with the photosensitive drum 2 at the facing position. At the same time as the toner T on the roller 103 is rubbed and collected, the toner T adhering to the supply roller 105 is applied to the surface of the developing roller 103 and supplied.

  A roller coated with an elastic rubber layer is used as the developing roller 103, and a surface coat layer made of a material that is easily charged to a polarity opposite to that of the toner T is provided on the surface. The elastic rubber layer is set to a hardness of 50 degrees or less according to JIS-A in order to keep the contact state with the photosensitive drum 2 uniform, and further, an electrical resistance of 3 to 10 Ω in order to act a developing bias. Set to a value. The surface roughness Ra is set to 0.2 to 2.0 μm, and a necessary amount of toner is held on the surface. Further, in order to develop the latent image on the opposing photosensitive drum 2, a DC voltage is applied to the developing roller 103 as a developing bias. An AC voltage may be superimposed on the DC voltage. The developing roller 103 is rotationally driven so as to move in the same direction as the surface movement direction of the photosensitive drum 2 at a position facing the photosensitive drum 2, and the toner T held on the surface is transferred to the toner layer regulating member 104 and the photosensitive drum 2. To the opposite position.

  The toner layer regulating member 104 is a blade using a stainless steel material such as SUS304CSP and SUS301CSP or a metal leaf spring material such as phosphor bronze, and the free end side is applied to the surface of the developing roller 103 with a pressing force of 10 to 100 N / m. The toner T that is in contact is thinned by the action of the pressing force, and a charge is applied by triboelectric charging and charge injection. Further, a DC voltage having a value offset in the same direction as the charging polarity of the toner T with respect to the applied voltage of the developing roller 103 is applied to the toner layer regulating member 104 in order to assist frictional charging. An AC voltage may be superimposed on the DC voltage.

The toner on the developing roller 103 that has been thinned by passing through a position facing the supply roller 105 and a position facing the toner layer regulating member 104 is conveyed to a position facing the photosensitive drum 2 and applied to the developing roller 103. In accordance with the developing bias and the latent image electric field formed by the electrostatic latent image on the photosensitive drum 2, it moves to the surface of the photosensitive drum 2 and is developed.
A sealing seal 109 is provided in contact with the developing roller 103 at a portion where the toner T not developed on the photosensitive drum 2 and left on the developing roller 103 returns to the toner supply chamber 102 again. Is sealed so as not to leak out of the developing device.

  A toner conveying member 106 is provided in the toner storage chamber 101. The toner conveyed to the opening 107a by the toner conveying member 106 moves to the toner supply chamber 102 by the action of gravity. The toner conveying member 106 may be provided with a toner stirring function. Specifically, it is desirable to form a plate-like stirring member in a portion corresponding to the opening 107a.

  The toner T moved to the toner supply chamber 102 is transported along the axial direction of the supply roller 105 by the toner transport member 108. At this time, the supply roller 105 attaches the toner and transfers it to the developing roller 103.

The portion corresponding to the bottom of the opening 107a of the toner conveying member 108 is provided with a stirring blade 108a, and the other portion is provided with a screw 108b. The screw 108b has a function of transporting toner in the direction of its rotation axis. The stirring blade 108a has a smaller toner conveying force in the direction of the rotation axis than that. Thus, by reducing the conveying force in the rotation axis direction of the toner conveying member 108 under the opening 107a, a toner reservoir is formed under the opening 107a, and the toner is excessively dropped and supplied from the toner storage chamber 101. To prevent it. The toner conveying member 108 is not limited to such a configuration, and may be any structure as long as the toner conveying force below the opening 107a is smaller than that of other portions.
Further, the stirring blade 108a stirs the toner below the opening 107a, thereby preventing toner aggregation in the toner pool. Note that the stirring member of the toner conveying member 108 is not limited to such a form, and any member that stirs the toner below the opening 107a may be used.

The toner below the opening 107a gradually moves to the periphery while being stirred by the stirring blade 108a of the toner transport member 108, and is transported by the screw 108b. When the conveyed toner reaches below the opening 107b, a part of the toner moves into the toner storage chamber 101 above the opening 107b by powder pressure. In order to increase the movement efficiency, it is desirable to control the toner conveyance so that the toner powder pressure is increased under the opening 107b.
The toner that has moved to the toner storage chamber 101 is again transported to the opening 107 a by the toner transport member 106 and moves to the toner supply chamber 102.

  Thus, the toner T in the developing device moves and circulates in the toner storage chamber 101 and the toner supply chamber 102, and at the same time, a part of the toner in the toner supply chamber 102 moves on the developing roller 103 by the supply roller 105. Further, a part of the toner moves to the photosensitive drum 2 in order to develop the latent image on the photosensitive drum 2.

In the image forming apparatus shown in FIG. 1, the four image forming units 1Y, 1M, 1C, and 1K are equipped with a process cartridge unit including the developing device 4 configured as described above. In FIG. 5, when the solid belt-like pattern is continuously printed, the reversely charged toner increases in the thin layer toner on the developing roller 103 of each developing device 4. This is because when the solid image is developed, the toner newly supplied to the developing roller 103 is not sufficiently charged. On the other hand, when white is printed, the toner on the developing roller 103 is not developed, and a part thereof becomes a thin layer on the developing roller again. That is, since a part of the toner charged once after passing through the regulation nip with the toner layer regulating member 104 becomes a thin layer again, the chargeability is better than the thin layer after solid development.
If solid development is performed, new uncharged toner passes through the nip between the developing roller 103 and the toner layer regulating member 104. If solid development is continuously performed, it will eventually develop to be fixed.

Therefore, in the present invention, by controlling the rotation of the developing roller 103, the charging property can be maintained without deteriorating the developability of the toner on the developing roller, and the occurrence of toner sticking to the toner layer regulating member 104 can be prevented. Is.
That is, in the rotation control method in the image forming apparatus of the present invention, the development amount analyzing means is provided, the development amount analysis is executed at a predetermined timing during the image forming operation, and the rotation of the developing roller is controlled according to the analysis result. By doing so, the chargeability is maintained without deteriorating the developability of the toner on the developing roller, and the occurrence of toner sticking to the toner layer regulating member 104 is also prevented.
As described above, the control unit (not shown) of the image forming apparatus has the function as the development amount analyzing unit.

In the rotation control method of the present invention, the development amount analysis means (control section) causes the surface of the developing roller 103 to move in the main scanning direction (that is, the direction parallel to the axis) in the exposure means (for example, an optical scanning device (laser beam scanner)). The development amount in each of the divided areas is calculated, and the ratio of the development amount to the predetermined surface travel distance of the photosensitive drum 2 is calculated.
Then, it is determined whether the development amount is large or small at the same position in the axial direction on the developing roller 103.
Further, since development is not normally performed between images, the chargeability of the thin layer toner is restored. For this reason, the necessity for rotation control of the developing roller 103 is determined based on the development amount at the travel distance including the interval between the images, and the rotation control is performed.

In the rotation control method of the present invention, the development amount analyzing means (control unit) divides the print area of the recording medium (transfer paper) P into a predetermined length in the main scanning direction of the exposure means, and The development amount in the region is calculated, and the ratio of the development amount to the predetermined surface travel distance of the photosensitive drum 2 is calculated.
In this way, the development amount on the recording medium can be calculated to determine the necessity of rotation control of the developing roller 103.

  Further, in the rotation control method of the present invention, the timing for controlling the rotation of the developing roller 103 by executing the developing amount analysis by the developing amount analyzing means (control unit) can be determined by the number of continuously printed sheets. That is, the toner charge on the developing roller is significantly reduced during continuous printing at a high density. Therefore, the necessity for rotation control of the developing roller 103 may be determined based on the number of continuous prints.

In the rotation control method of the present invention, the development amount analyzing means (control unit) can calculate the development amount from the image data. Usually, since the image data is binarized, the development amount can be calculated from binarized data for each line (for example, 1: black part (toner adhesion), 0: white part).
Further, in the rotation control method of the present invention, the development amount analyzing means (control unit) can calculate the development amount from the exposure information. For example, the development amount can be calculated from a writing signal (ON / OFF signal) per one scan of laser light.

In the rotation control method of the present invention, the development amount analyzing means (control unit) can perform the 103 rotation control of the developing roller at a timing different from the normal image forming sequence.
Thereby, after the charge property of the thin layer toner is lowered in the normal image forming sequence, the charge property can be recovered by turning control.

Further, in the rotation control method of the present invention, the development amount analyzing means (control unit) controls the rotation of the developing roller 103 so that the development amount with respect to a predetermined surface travel distance of the photosensitive drum 2 at a plurality of division positions in the main scanning direction. If the maximum value of the ratio is equal to or greater than the predetermined value, the developing roller 103 is rotated for a predetermined time in addition to the normal sequence, and if it is less than the predetermined value, it is determined that the normal sequence remains.
That is, when developing at a density that is a certain travel distance or more, the chargeability of the thin toner is reduced, and therefore development for a predetermined surface travel distance of the photosensitive drum 2 at a plurality of division positions in the main scanning direction. When the maximum value among the ratios of the amounts is equal to or greater than a predetermined value, the developing roller 103 is rotated for a predetermined time in addition to the normal sequence to recover the chargeability.

Further, in the rotation control method of the present invention, the development amount analyzing means (control unit) executes rotation control of the developing roller 103 at a plurality of timings.
By executing the process at a plurality of times as described above, it is possible to cope with a case where the image density of the image in the job changes.

In the rotation control method of the present invention, as the number of rotation control timings of the developing roller 103 increases, the set value of the ratio of the development amount serving as a determination criterion decreases.
In the rotation control method of the present invention, as the number of rotation control timings of the developing roller 103 increases, the setting value of the time for rotating the developing roller 103 when the ratio of the developing amount is equal to or greater than a predetermined value is increased. It has become.
Further, in the rotation control method of the present invention, when the rotation control of the developing roller 103 is executed based on the development amount analysis result, the development amount analysis timing is reset even when all the continuous printing jobs are not completed. ing.

  Specific examples and comparative examples of the rotation control of the developing roller in the image forming apparatus of the present invention are shown below.

[Example]
In the present embodiment, the development amount analyzing means (control unit) determines the timing for determining whether or not the rotation of the developing roller 103 is controlled based on the number of continuous prints as follows.
-Continuous printing 10th sheet-Continuous printing 15th sheet-Continuous printing 20th sheet-Continuous printing 30th sheet

  As a determination method, the surface of the developing roller 103 has a predetermined length in the main scanning direction (that is, the direction parallel to the axis of the photosensitive drum 2 and the developing roller 103) in the exposure unit (for example, an optical scanning device (laser beam scanner)). Then, the development amount in each of the divided areas is calculated, and the ratio of the development amount to the predetermined surface travel distance of the photosensitive drum 2 is calculated. More specifically, the surface of the developing roller 103 is divided by 2 mm in the main scanning direction at the timing of each number of sheets, and the ratio of the developing amount to the travel distance of the photosensitive drum 2 in each 2 mm width ( Here, what percentage corresponds to solid printing) is calculated.

When the ratio (development ratio) of the developing amount corresponding to the solid printing with respect to the photosensitive drum traveling distance of the developing roller for each continuous printing number becomes equal to or larger than the following value, the rotation control of the developing roller 103 is turned ON, and the developing roller 103 is rotated for 20 seconds. FIG. 4 shows the relationship between the number of continuously printed sheets and the development ratio with respect to the photosensitive member travel distance of the developing roller, and the range in which the rotation control is turned on.
-Continuous printing 10th sheet 77%
・ Continuous printing 15th sheet 65%
-Continuous printing 20th sheet 50%
・ Continuous printing 30th sheet 40%

  By controlling the rotation of the developing roller 103 in accordance with the ratio of development amount (development ratio) as described above, a job of 50 continuous prints is repeated 100 times, and a total of 5000 sheets are printed. As a result, the toner layer regulating member (blade) 104 No white streaks due to the toner sticking to the surface were generated.

[Comparative example]
As a comparative example, the rotation control of the developing roller 103 was not performed under the printing conditions of the above embodiment. As a result, white streaks caused by the toner sticking to the toner layer regulating member (blade) 104 after printing 5000 sheets occurred.

  As is clear from the results of the above examples and comparative examples, the development amount analysis means (control unit) executes the development amount analysis at a timing corresponding to the number of continuous prints during the image forming operation, and according to the analysis result. By controlling the rotation of the developing roller 103, the chargeability can be maintained without deteriorating the developability of the toner on the developing roller, and the occurrence of toner sticking to the toner layer regulating member 104 can be prevented. Can do. Therefore, good image formation can be maintained for a long time by using the above rotation control method.

1 is a diagram illustrating an embodiment of the present invention, and is a schematic cross-sectional view illustrating a main configuration of a tandem type image forming apparatus including a plurality of image forming units. FIG. 2 is a schematic cross-sectional view showing a simplified cross-sectional configuration of a process cartridge unit used in the image forming apparatus shown in FIG. 1. FIG. 3 is a schematic cross-sectional view of a main part showing a main part configuration of a developing device portion of the process cartridge unit shown in FIG. 2. It is a figure which shows the relationship of the developing ratio with respect to the continuous printing number of sheets and the travel distance of a developing roller, and the range which turns ON rotation control.

Explanation of symbols

1Y, 1M, 1C, 1K1: Image forming unit (process cartridge)
2: Photosensitive drum (latent image carrier)
3: Charging roller (charging means)
4: Developing device (developing means)
5: Cleaning device (cleaning means)
6: Optical scanning device (exposure means)
7: Intermediate transfer belt (intermediate transfer member)
8: Primary transfer roller 9: Secondary transfer roller 10: Intermediate transfer belt cleaning means 11A, 11B: Paper feed cassette 12: Paper feed roller 13: Separation roller 14: Conveyance roller 15: Registration roller 16: Fixing device 101: Toner storage Chamber 102: Toner supply chamber 103: Developing roller (toner carrier)
104: toner layer regulating member 105: supply roller 106: toner conveying member 107a, 107b: opening 108: toner conveying member 108a: stirring blade 108b: screw 109: sealing seal P: transfer paper (recording medium)
T: Toner

Claims (13)

A latent image carrier capable of rotating and supporting a latent image, a latent image forming unit that exposes the latent image carrier with an exposure unit to form a latent image, and a latent image on the latent image carrier is converted into a toner. A rotation control method in an image forming apparatus having a toner carrier that can be driven to rotate by developing,
A development amount analysis unit, wherein the development amount analysis unit executes a development amount analysis at a predetermined timing during an image forming operation, and controls the rotation of the toner carrier according to the analysis result. Rotation control method to do. The rotation control method according to claim 1,
The development amount analyzing unit divides the surface of the toner carrier into a predetermined length in the main scanning direction of the exposure unit, calculates a development amount in each of the divided areas, and the latent image carrier A rotation control method, comprising: means for calculating a ratio of the development amount to a predetermined surface travel distance. The rotation control method according to claim 1,
The development amount analyzing unit divides the print area of the recording medium into a predetermined length in the main scanning direction of the exposure unit, calculates a development amount in each of the divided regions, and determines a predetermined amount of the latent image carrier. A rotation control method, characterized in that the rotation control method is means for calculating a ratio of the development amount to a surface travel distance. In the rotation control method according to any one of claims 1 to 3,
2. A rotation control method according to claim 1, wherein a timing for controlling the rotation of the toner carrying member by executing a development amount analysis by the development amount analysis means is determined by a continuous print number. In the rotation control method according to any one of claims 1 to 4,
A rotation control method, wherein the development amount is calculated from image data. In the rotation control method according to any one of claims 1 to 5,
A rotation control method, wherein the development amount is calculated from exposure information. In the rotation control method according to any one of claims 1 to 6,
A rotation control method, wherein the rotation control of the toner carrier is performed at a timing different from a normal image forming sequence. In the rotation control method according to any one of claims 1 to 7,
When the rotation control of the toner carrier is a predetermined value or more of a ratio of the development amount to a predetermined surface travel distance of the latent image carrier at a plurality of division positions in the main scanning direction, A rotation control method, comprising: rotating the toner carrier for a predetermined time in addition to the sequence; and determining that the normal sequence is maintained when the toner carrier is less than a predetermined value. In the rotation control method according to any one of claims 1 to 8,
A rotation control method, wherein the rotation control of the toner carrier is executed at a plurality of timings. The rotation control method according to claim 9, wherein
The rotation control method according to claim 1, wherein the set value of the ratio serving as a determination reference decreases as the number of times of rotation control timing of the toner carrier increases. The rotation control method according to claim 9 or 10,
A rotation control method characterized in that, as the number of times of rotation control timing of the toner carrier increases, a set value of a time for rotating the toner carrier when the ratio is equal to or greater than a predetermined value is increased. In the rotation control method according to any one of claims 9 to 11,
A rotation control method characterized in that when the rotation control of the toner carrier is executed based on the development amount analysis result, the development amount analysis timing is reset even when all the continuous printing jobs are not completed. A latent image carrier capable of rotating and supporting a latent image, a latent image forming unit that exposes the latent image carrier with an exposure unit to form a latent image, and a latent image on the latent image carrier is converted into a toner. In an image forming apparatus having a toner carrier that can be rotated and developed by
An image forming apparatus using the rotation control method according to claim 1 as means for controlling rotation of the toner carrier.

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