JP2004053942A - Image forming device - Google Patents

Abstract

An object of the present invention is to suppress an adverse effect on image quality due to a rotating body contacting an image carrier.
When the image forming apparatus is started up from a stop state, that is, when the power supply is turned on or started up from a preheating mode, a cleaning brush 201a as a brush-like rotating body that is in contact with a photosensitive drum 200 is set to a predetermined value. By rotating the cleaning brush 201a for a time, the hair falling state of the cleaning brush 201a is returned to the original state, and the fluctuation of the rotation load of the cleaning brush 201a on the photosensitive drum 200 is corrected. The rotation time of the cleaning brush 201a measures the elapsed time from the previous rotation, and changes according to the measurement time.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.
[0002]
[Prior art]
In this type of image forming apparatus, for example, after uniformly charging the surface of a photoreceptor as an image carrier by a charging device, an electrostatic latent image is formed based on image information of a document, and the electrostatic latent image is formed. A toner image is visualized as a toner image by a developing device, the toner image is transferred to a recording medium by a transfer device, and then the toner image is fixed to the recording medium by heat and pressure by a fixing device.
In color image formation, a method is also employed in which a toner image on a photoreceptor is superimposed and transferred onto an intermediate transfer member and then transferred to a recording medium.
After the toner image is transferred to the intermediate transfer member, the toner remains on the photoconductor. Further, it is inevitable that the toner remains on the photoreceptor or the intermediate transfer body after the toner image is transferred to the recording medium, and that the paper powder of the transfer paper as the recording medium and a small amount of additives adhere thereto. In this case, particularly, a small amount of transfer paper, or a discharge product generated by corona discharge or the like adheres to the surface of the photoreceptor, so that it is not easy to remove it. It has become.
[0003]
Generally, as shown in FIG. 9, the cleaning device includes a cleaning fur brush (hereinafter also simply referred to as a cleaning brush or brush) 701 as a brush-like rotating body that rotates in contact with the surface of the photoconductor 700. It has a cleaning blade 702 and the like. In FIG. 9, reference numeral 703 denotes a toner collecting coil, 704 denotes a cleaning blade pressure spring, 705 denotes a transfer paper separating claw, and 706 denotes a photoconductor motor.
The cleaning fur brush 701 has a main purpose of removing paper dust generated from the transfer paper and removing a small amount of additives in the transfer paper adhered to the surface of the photoconductor 700, and is directed in the direction of the arrow in the same direction as the photoconductor 700. Is driven to rotate. As an additional effect, it also plays the role of toner cleaning and the transport of toner scraped off the photoreceptor surface by the cleaning blade 702 downstream thereof.
[0004]
[Problems to be solved by the invention]
By the way, if the image forming operation is not performed for a long time, the cleaning brush does not rotate, so that a certain portion of the hair remains in contact with the image carrier and only that portion is deformed (hair fall). Would.
If the image forming operation is performed in this state, when the cleaning brush rotates, the rotation load of the cleaning brush on the photoreceptor changes between the fallen portion and the normal portion, which is called banding on the image. A stripe pattern (periodic density change) occurs.
Japanese Patent Application Laid-Open No. 3-269777 discloses a technique for preventing the above-mentioned deformation phenomenon by rotating a cleaning brush when a new cartridge having a cleaning brush is set in the apparatus.
However, the hair falling phenomenon occurs not only when the brush is new, but also when the device is not used for a long time.
[0005]
Further, as described above, the trace additive in the transfer paper sticks to the surface of the photoreceptor. Therefore, in order to clean such deposits, it is necessary to use a strong and thick yarn having a large thickness for the cleaning fur brush. However, when such a cleaning brush is used, the original yarn is thick and strong, which may damage the surface of the photoreceptor and cause abnormal wear.
For example, if the amount of toner input to the cleaning device is extremely small, the surface of the cleaning fur brush has little or no toner attached to it, and contacts and rubs with the photoreceptor. Then, the surface of the photoconductor is damaged. Further, if the cleaning fur brush and the drive source for driving the photosensitive member are the same, a pitch-like flaw occurs at the least common multiple of the number of teeth of the transmitting gear or timing belt.
[0006]
The mechanism by which pitch-like scratches can be formed on the photoconductor will be described with reference to FIGS. The diameter of the photoconductor 700 is 100 mm, and the outer diameter of the cleaning fur brush 701 is 18 mm. When the cleaning fur brush 701 is cut into the photoconductor 700 by about 1.5 mm and rubbed, the pitch circle of the cleaning fur brush 701 with respect to the photoconductor 700 becomes 15 mm. The pitch circle is set to be the same as the linear speed of the photoconductor 700.
The linear velocities of the pitch circles of the photoconductor 700 and the cleaning fur brush 701 are approximately the same and 350 mm / sec.
As shown in FIG. 10, the driving force is transmitted to the photoconductor 700 directly from the photoconductor motor output shaft 708 to the photoconductor gear 709, and the driving force is transmitted to the cleaning fur brush 701 via one idler gear 710. I have.
[0007]
In FIG. 10, reference numeral 712 denotes a photoconductor motor, 713 denotes a transmission shaft to the cleaning fur brush, 714 denotes a transmission shaft to the photoconductor, and 715 denotes a shaft (coupling portion) of the cleaning fur brush. Is shown. A photoconductor and a cleaning fur brush exist on the unit 716 side.
The number of teeth of the photoconductor gear 709 is 156, the number of teeth of the idler gear 710 is 39/59, and the number of teeth of the gear 711 of the cleaning fur brush 701 is 39. From the relationship of the number of teeth, the cleaning fur brush 701 makes 236 rotations with respect to 39 rotations of the photoconductor 700, and the same original point is hit. Accordingly, the pitch of one rotation cycle trace of the cleaning fur brush 701 is about 314 (perimeter of the photoconductor 700) / 236 = about 1.33 mm pitch. For example, when one point of hard foreign matter adheres to the outer periphery of the cleaning fur brush 701, the cleaning fur brush 701 rotates 236 times and hits the original point of the photoconductor 700.
Therefore, 236 points are formed on the photoconductor 700 before the original point is hit, and the photoconductor 700 is damaged at a pitch of 314/236 = 1.33 mm. In this state, even if the linear velocity difference between the photoreceptor 700 and the cleaning fur brush 701 is given, even if the number of teeth of the gear is changed, only the interval is changed, and a pitch-like flaw is generated.
[0008]
Accordingly, an object of the present invention is to provide an image forming apparatus capable of suppressing an adverse effect on image quality due to a rotating body or a brush-shaped rotating body that comes into contact with an image carrier.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, in an image forming apparatus having an image carrier and a brush-like rotating body that rotates in contact with the image carrier, the apparatus is started from a stopped state. At this time, a configuration is adopted in which the brush-like rotating body is rotated for a predetermined time.
[0010]
According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the rotation of the brush-like rotator is performed during a warm-up time of the apparatus.
[0011]
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the rotation of the brush-like rotating body is performed before a process control operation during the warm-up time.
[0012]
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, when the brush-shaped rotator rotates, the image carrier is also rotated. I have.
[0013]
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, there is provided an elapsed time measuring means for measuring an elapsed time from a previous rotation of the brush-like rotating body. Then, the predetermined time is changed according to the elapsed time.
[0014]
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the brush-like rotator is a cleaning brush for cleaning toner remaining on the image carrier. There is a configuration that there is.
[0015]
According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the brush-like rotating body is an application brush for applying a lubricant onto the image carrier. , Is adopted.
[0016]
According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the brush-like rotator is a bias applying brush for applying a bias to the image carrier. , Is adopted.
[0017]
According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the brush-like rotating body is a charging brush for charging the image carrier. I am taking it.
[0018]
According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the configuration is such that the brush-like rotator is a static elimination brush that neutralizes the image carrier. I am taking it.
[0019]
According to an eleventh aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier; and a rotator that rotates in contact with the image carrier, wherein the rotator is rotationally driven by the same drive source as the image carrier. , The image carrier is provided such that a rotational position shift with respect to the rotator is caused by a reverse rotation operation of the image carrier.
[0020]
According to a twelfth aspect of the present invention, in the image forming apparatus of the eleventh aspect, the rotational position shift is performed by a one-way clutch provided in a drive transmission path of the rotating body.
[0021]
According to an embodiment of the present invention, there is provided an image forming apparatus comprising: an image carrier; and a rotator that rotates in contact with the image carrier, wherein the rotator is rotationally driven by the same drive source as the image carrier. In this configuration, the image carrier and the rotating body are provided so as to cause a rotational displacement.
[0022]
According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, the rotational position shift is performed by a torque limiter provided in a drive transmission path of the rotating body.
[0023]
According to a fifteenth aspect of the present invention, in the image forming apparatus according to any one of the eleventh to fourteenth aspects, the rotating body is a cleaning brush, and a tip of the brush is formed in a loop shape. Surface pressure is 50g / cm ² The above configuration is adopted. Here, the surface pressure means a contact pressure between the cleaning brush and the image carrier when a target bite amount into the image carrier is secured.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration and operation of an electrophotographic color copying machine (hereinafter, referred to as a “color copying machine”) as an image forming apparatus according to the present embodiment will be described with reference to FIG. The color copying machine includes a color image reading device (hereinafter, referred to as “color scanner”) 1, a color image recording device (hereinafter, referred to as “color printer”) 2, a paper feed bank 3, and the like.
[0025]
The color scanner 1 forms an image of the document 4 on the contact glass 101 on a color sensor 105 via an illumination lamp 102, mirror groups 103a, 103b, 103c, and a lens 104, and outputs color image information of the document 4 for example. Red: red, Green: green, and Blue: blue (hereinafter, referred to as R, G, and B, respectively) are read for each color separation light and converted into electrical image signals. In the present embodiment, the color sensor 105 includes R, G, and B color separation means and a photoelectric conversion element such as a CCD, and simultaneously reads three color images obtained by performing color separation on the document 4.
The R, G, and B color separation image signals obtained by the color scanner 1 are subjected to color conversion processing by an image processing unit (not shown) based on the intensity level, and Black: black (hereinafter, referred to as Bk), Cyan: cyan. (Hereinafter, referred to as C), Magenta: magenta (hereinafter, referred to as M), and Yellow: yellow (hereinafter, referred to as Y) color image data are obtained.
[0026]
The operation of the color scanner 1 for obtaining the color image data of Bk, C, M, and Y is as follows. Upon receiving a scanner start signal which is timed with the operation of the color printer 2 described later, the optical system including the illumination lamp 102 and the mirror groups 103a, 103b, 103c scans the original 4 in the direction of the arrow (left direction). One color image data is obtained for each scan. By repeating this operation a total of four times, each color separation light of, for example, red, green, and blue (hereinafter, referred to as “R”, “G”, and “B”) is read and converted into an electrical image signal. Alternatively, R, G, and B image data are stored in the memory.
When a memory (not shown) is used, RGB three-color image data is obtained by one scan. Then, each time the color printer 2 sequentially visualizes the images and superimposes them to form a final four-color full-color image.
[0027]
The color printer 2 includes a photosensitive drum 200 as an image carrier, a writing optical unit 220, a revolver developing unit 230 as a developing device, an intermediate transfer unit 500, a secondary transfer unit 600, a fixing device 270, and the like.
The photoreceptor drum 200 rotates in a counterclockwise direction indicated by an arrow. Around the photoreceptor cleaning device 201, a static elimination lamp 202, a charger 203, a potential sensor 204, and a selected development of a revolver development unit 230. , A development density pattern detector 205, an intermediate transfer belt 501 of the intermediate transfer unit 500, and the like.
[0028]
The writing optical unit 220 converts the color image data from the color scanner 1 into an optical signal, and irradiates the surface of the photosensitive drum 200 uniformly charged by the charger 203 with laser light corresponding to the image of the document. Then, optical writing is performed to form an electrostatic latent image on the surface of the photosensitive drum 200.
The writing optical unit 220 includes, for example, a semiconductor laser 221 as a light source, a laser emission drive control unit (not shown), a polygon mirror 222 and its rotation motor 223, an f / θ lens 224, a reflection mirror 225, and the like.
The revolver developing unit 230 includes a Bk developing device 231K using Bk toner, a C developing device 231C using C toner, an M developing device 231M using M toner, and a Y developing device 231Y using Y toner. And a developing revolver driving unit (not shown) that rotates the developing unit.
[0029]
Each developing unit installed in the revolver developing unit 230 includes a developing sleeve as a developing material carrier that rotates by contacting a spike of the developing material with the surface of the photosensitive drum 200 to develop an electrostatic latent image, It comprises a developer paddle that rotates to pump up and agitate the developer, and a developing sleeve drive unit that rotates the developing sleeve clockwise as indicated by the arrow.
The toner in each developing unit is negatively charged by stirring with the ferrite carrier. A developing bias voltage in which an AC voltage Vac (AC component) is superimposed on a negative DC voltage Vdc (DC component) is applied to each developing sleeve by a developing bias power source (not shown) as a developing bias applying unit. It is biased at a predetermined potential with respect to the metal base layer of the body drum 200.
[0030]
In the standby state of the main body of the color copying machine, the revolver developing unit 230 is stopped at the home position where the Bk developing device 231K is located at the developing position, and when the copy start key is pressed, the Bk color is started by the color scanner 1 at a predetermined timing. Reading of image data is started, and optical writing by a laser beam, that is, formation of an electrostatic latent image is started based on the color image data (hereinafter, an electrostatic latent image based on Bk image data is referred to as “Bk electrostatic latent image”). The same applies to C, M, and Y).
Before the front end of the electrostatic latent image reaches the Bk development position, the rotation of the Bk developing sleeve is started to convert the Bk electrostatic latent image with Bk toner so that development can be performed from the front end of the Bk electrostatic latent image. develop.
Thereafter, the developing operation of the Bk electrostatic latent image is continued, but when the trailing end of the Bk electrostatic latent image passes the Bk developing position, the revolver developing unit is immediately operated until the developing device of the next color comes to the developing position. 230 rotates. This is completed at least before the leading end of the electrostatic latent image based on the next image data reaches the developing position.
[0031]
As shown in FIG. 2, the intermediate transfer unit 500 includes an intermediate transfer belt 501, which is an intermediate transfer member stretched over a plurality of rollers described later. Around the intermediate transfer belt 501, a secondary transfer belt 601 as a transfer material carrier of the secondary transfer unit 600, a secondary transfer bias roller 605 as a secondary transfer charge applying unit, and an intermediate transfer body cleaning unit. A belt cleaning blade 504, a lubricant application brush 505 serving as a lubricant application unit, and the like are arranged to face each other. In FIG. 1, the lubricant application brush 505 and the like are omitted.
The intermediate transfer belt 501 is stretched around a primary transfer bias roller 507, a belt driving roller 508, a belt tension roller 509, a secondary transfer facing roller 510, a cleaning facing roller 511, and an earth roller 512, which are primary transfer charge applying means. Have been. Each roller is formed of a conductive material, and each roller other than the primary transfer bias roller 507 is grounded.
[0032]
A position detection mark MC is provided on the outer peripheral surface or the inner peripheral surface of the intermediate transfer belt 501. However, on the outer peripheral surface side of the intermediate transfer belt 501, it is necessary to devise a method of providing the position detection mark MC so as to avoid the pass area of the belt cleaning blade 504, which may cause difficulty in arrangement. Is provided with a position detection mark MC on the inner peripheral surface side of the intermediate transfer belt 501. The optical sensor 514 as a mark detection sensor is provided at a position between the bias roller 507 and the drive roller 508 around which the intermediate transfer belt 501 is stretched.
A transfer bias controlled to a predetermined magnitude of current or voltage in accordance with the number of superimposed toner images is applied to the primary transfer bias roller 507 by a primary transfer power supply 801 controlled by a constant current or a constant voltage. ing. The intermediate transfer belt 501 is driven in a direction indicated by an arrow by a belt drive roller 508 that is driven to rotate by a drive motor (not shown).
[0033]
The intermediate transfer belt 501 is made of a semiconductor or an insulator and has a single-layer or multilayer structure, which will be described later. In a transfer unit that transfers the toner image on the photosensitive drum 200 to the intermediate transfer belt 501 (hereinafter, referred to as “primary transfer unit”), the primary transfer bias roller 507 and the ground roller 512 transfer the intermediate transfer belt 501 to the photosensitive drum 200. The nip portion having a predetermined width is formed between the photosensitive drum 200 and the intermediate transfer belt 501 by being stretched so as to be pressed against the side.
The lubricant application brush 505 is for polishing zinc stearate 506 as a lubricant formed in a plate shape and applying the polished fine particles to the intermediate transfer belt 501. The lubricant application brush 505 is also configured to be adjacent to the intermediate transfer belt 501, and is controlled so as to contact the intermediate transfer belt 501 at a predetermined timing.
[0034]
The secondary transfer unit 600 includes a secondary transfer belt 601 stretched over three support rollers 602, 603, and 604, and a stretched portion between the support rollers 602 and 603 of the intermediate transfer belt 501 is subjected to secondary transfer. It can be pressed against the opposing roller 510. One of the three support rollers 602, 603, and 604 is a driving roller that is driven to rotate by a driving unit (not shown), and the driving roller drives the secondary transfer belt 601 in a direction indicated by an arrow in the drawing.
The secondary transfer bias roller 605 is a secondary transfer unit, is disposed so as to sandwich the intermediate transfer belt 501 and the secondary transfer belt 601 between the secondary transfer opposing roller 510, and is controlled at a constant current. A transfer bias of a predetermined current is applied by the next transfer power supply 802.
The supporting roller 602 and the secondary transfer bias roller 605 are positioned so that the secondary transfer belt 601 and the secondary transfer bias roller 605 can take a position where the secondary transfer belt 601 and the secondary transfer bias roller 605 are pressed against the secondary transfer facing roller 510 and a position where the secondary transfer belt 601 and the secondary transfer bias roller 605 separate. An unillustrated separation / contact mechanism that drives the transfer bias roller 605 in the direction of the arrow is provided.
In FIG. 2, reference numeral 209 denotes a pair of registration rollers, and a predetermined timing is provided between the intermediate transfer belt 501 and the secondary transfer belt 601 sandwiched between the secondary transfer bias roller 605 and the secondary transfer opposing roller 510. Then, the transfer paper P as a recording medium is fed.
[0035]
A portion of the secondary transfer belt 601 which is stretched around the support roller 603 on the side of the fixing device 270 includes a transfer sheet charge removal unit 606 as a transfer material charge removal unit and a belt charge removal unit 607 as a transfer material carrier charge removal unit. Are provided facing each other. A cleaning blade 608, which is a transfer material carrier cleaning unit, is in contact with a portion of the secondary transfer belt 601 that is stretched around the lower support roller 604 in the drawing.
The transfer paper discharging charger 606 discharges the electric charges held in the transfer paper, so that the transfer paper can be satisfactorily separated from the secondary transfer belt 601 by the rigidity of the transfer paper itself. The belt static elimination charger 607 eliminates electric charges remaining on the secondary transfer belt 601. The cleaning blade 608 is for removing the adhered matter attached to the surface of the secondary transfer belt 601 for cleaning.
[0036]
Transfer papers of various sizes are stored in the transfer paper cassette 207 in the color printer 2 and the transfer paper cassettes 30a, 30b, 30c in the paper supply bank 3, and are supplied from the transfer paper cassette of the designated size. The paper is fed and conveyed in the direction of the registration roller pair 209 by the paper rollers 208, 31a, 31b, 31c.
On the right side of the color printer 2, a manual paper feed tray 210 for special paper such as OHP paper or thick paper is provided.
[0037]
When the image forming cycle is started in the color copying machine having the above-described configuration, first, the photosensitive drum 200 is turned in the counterclockwise direction indicated by an arrow, and the intermediate transfer belt 501 is turned clockwise in the direction indicated by an arrow. It is rotated at linear speed.
As described above, the position detection mark MC is provided on the back side of the intermediate transfer belt 501. The position detection mark MC moves together with the intermediate transfer belt 501, and an optical sensor 514 is attached to a stationary member in a predetermined passage area through which the position detection mark MC passes.
As the optical sensor 514, a reflection photosensor or a transmission photosensor is used. When a reflection type photo sensor is used as the optical sensor 514, a member such as a reflective tape is attached to the intermediate transfer belt 501, and the reflection type photo sensor applies a mark from the low reflection surface on the intermediate transfer belt 501 to the mark MC. What is necessary is just to read the place where it changes, or the place where it changes from the position detection mark MC to the surface with low reflectivity on the intermediate transfer belt 501.
[0038]
With the rotation of the intermediate transfer belt 501, Bk toner image formation, C toner image formation, M toner image formation, and Y toner image formation are performed, and primary transfer is performed by a transfer bias by a voltage applied to a primary transfer bias roller 507. Is performed, and a toner image is finally formed on the intermediate transfer belt 501 in the order of Bk, C, M, and Y.
For example, Bk toner image formation is performed as follows. The charger 203 uniformly charges the surface of the photosensitive drum 200 to a predetermined potential with negative charge by corona discharge. After a certain period of time after the detection of the position detection mark MC by the optical sensor 514, optical writing using the following Bk image data is performed.
Then, based on the color image signal converted from the image data stored in the RGB memory, the writing optical unit 220 performs raster exposure with laser light of Bk data. When this raster image is exposed, in the exposed portion of the surface of the photosensitive drum 200 that is initially uniformly charged, the charge proportional to the amount of exposure light disappears, and a Bk electrostatic latent image is formed.
[0039]
When the negatively charged Bk toner on the Bk developing roller of the Bk developing device 231K comes into contact with the Bk electrostatic latent image, the toner does not adhere to the portion of the photosensitive drum 200 where the charge remains, and the charge is not applied. The toner is attracted to the portion without the mark, that is, the exposed portion, and a Bk toner image similar to the electrostatic latent image is formed.
The Bk toner image formed on the photosensitive drum 200 is transferred onto the surface of the intermediate transfer belt 501 that is driven at a constant speed in contact with the photosensitive drum 200. Hereinafter, the transfer of the toner image from the photosensitive drum 200 to the intermediate transfer belt 501 is referred to as “primary transfer”.
A small amount of untransferred residual toner remaining on the surface of the photoconductor drum 200 after the belt transfer is cleaned by the photoconductor cleaning device 201 in preparation for reuse of the photoconductor drum 200. The photoconductor cleaning device 201 includes a cleaning brush 201a as a brush-like rotating body and a cleaning blade 201b.
Similarly, each time the intermediate transfer belt 501 makes one rotation, the position sensor mark MC is detected by the optical sensor 514, and the photoconductor drum 200 side follows the Bk image forming process at the same timing as Bk, that is, the optical sensor. A fixed time after the detection of the position detection mark MC by 514, optical writing with C image data, optical writing with M image data, and optical writing with Y image data are performed.
When the process proceeds to the C image forming step, calling of the converted C image data from the RGB memory starts at a predetermined timing, and a C electrostatic latent image is formed on the surface of the photosensitive drum 200 by writing the laser light based on the C image data. I do.
[0040]
After the trailing end of the previous Bk electrostatic latent image has passed and before the leading end of the C electrostatic latent image has reached, the rotating operation of the revolver developing unit 230 is performed, and the C developing device 231C is moved to the developing position. Is set, and the C electrostatic latent image is developed with C toner.
Thereafter, the development of the C electrostatic latent image area is continued, but when the rear end of the C electrostatic latent image passes, the revolver developing unit rotates as in the case of the Bk developing device 231K, and the next operation is performed. Of the M developing device 231M is moved to the developing position. This is also completed before the leading end of the next M electrostatic latent image reaches the developing position.
Note that the M and Y image forming steps are the same as those of the above-described Bk and C steps, since the operations of retrieving the color image data, forming the electrostatic latent image, and developing are the same as those described above.
On the intermediate transfer belt 501, Bk, C, M, and Y toner images sequentially formed on the photosensitive drum 200 are transferred while being sequentially aligned on the same surface. As a result, a toner image in which a maximum of four colors are superimposed is formed on the intermediate transfer belt 501.
[0041]
At the time when the image forming operation is started, the transfer paper P is fed from either the transfer paper cassette or the manual feed tray, and stands by at the nip of the registration roller pair 209. Before the leading end of the toner image on the intermediate transfer belt 501 approaches the secondary transfer portion where the nip is formed by the secondary transfer opposing roller 510 and the secondary transfer bias roller 605, a secondary transfer contact / separation clutch (not shown) is operated. The secondary transfer unit 600 contacts the intermediate transfer belt 501. Thereafter, the registration roller pair 209 is driven such that the leading end of the transfer sheet P coincides with the leading end of the toner image, and registration of the transfer sheet P with the toner image is performed.
The transfer paper P is superimposed on the toner image on the intermediate transfer belt 501 and passes through the secondary transfer portion. At this time, the four-color superimposed toner image on the intermediate transfer belt 501 is collectively transferred onto the transfer paper by the transfer bias by the voltage applied to the secondary transfer bias roller 605 by the secondary transfer power supply 802. This is called “secondary transfer”.
The transfer paper P is discharged when passing through a portion facing the transfer paper discharging charger 606 disposed on the downstream side of the secondary transfer portion in the moving direction of the secondary transfer belt 601 and is separated from the secondary transfer belt 601 and conveyed. Move to belt 211.
[0042]
The transfer paper on which the four-color superimposed toner image is collectively transferred from the intermediate transfer belt 261 is conveyed to the fixing device 270 by the conveyance belt 211, and the toner image is formed at the nip between the fixing roller 271 and the pressure roller 272 controlled to a predetermined temperature. Is fused and fixed, sent out of the apparatus body by the discharge roller pair 212, and stacked face-up on a copy tray (not shown) to obtain a full-color copy.
On the other hand, the surface of the photoconductor drum 200 after the primary transfer is cleaned by the photoconductor cleaning device 201 and is uniformly discharged by the discharge lamp 202.
The toner remaining on the surface of the intermediate transfer belt 501 after the transfer of the toner image onto the transfer paper P is cleaned by a belt cleaning blade 504 pressed against the intermediate transfer belt 501 by a separation / contact mechanism (not shown).
[0043]
In the case of a repeat copy, the operation of the color scanner 1 and the image formation on the photosensitive drum 200 are performed at a predetermined timing following the image formation process of the fourth color (Y) of the first sheet (Bk). Then, the process proceeds to the image forming step of (2) In the case of the intermediate transfer belt 501, the second Bk toner image is transferred to the area of the front surface cleaned by the belt cleaning blade 504, following the batch transfer process of the first four-color superimposed toner image onto the transfer paper. Be transferred. Thereafter, the operation is the same as that of the first sheet. The above is the copy mode for obtaining a four-color full-color copy. However, in the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times.
In the case of the single-color copy mode, only the developing unit of the predetermined color of the revolver developing unit 230 is in the developing operation state until the predetermined number of sheets is completed, and the belt cleaning blade 504 is pressed against the intermediate transfer belt 501. The copy operation is performed with the position as it is.
[0044]
In the above-described image forming apparatus, if the image forming operation is not performed for a long period of time, the cleaning brush 201a in the photoconductor cleaning device 201 does not rotate, and as shown in FIG. It remains in contact with the body drum 200, and only that portion is deformed (hair falls).
If the image forming operation is performed in this state, when the cleaning brush 201a rotates, the rotational load of the cleaning brush 201a on the photosensitive drum 200 changes between the hair-tipped portion 201a-1 and the normal portion, and the In this case, a stripe pattern (periodic density change) called banding occurs.
Further, the state of the fluctuation of the rotation becomes larger as the time during which the image forming operation is not performed (pause time) is longer. FIG. 4 shows the relationship between the idle time of the apparatus and the rotation fluctuation rate. As described above, the fluctuation rate gradually increases as the pause time increases, but the value saturates at the point b after the time a.
[0045]
It is necessary to suppress this to c or less, which is a level that does not cause a problem on the image. For this purpose, the cleaning brush 201a may be rotated in advance before the image forming operation to restore the hair from falling.
FIG. 5 shows the rotation fluctuation rate after the cleaning brush 201a in a state where the rotation fluctuation rate is b in the saturated state in FIG. Since it is only necessary to set this to c or less, by rotating for d time, it is possible to eliminate the influence on the image due to the falling hair of the cleaning brush 201a.
Accordingly, when the cleaning brush 201a is rotated for d time (predetermined time) when the apparatus is started up from the stop state, it is possible to prevent an image defect due to hair fall formed when the apparatus was not used before that. . Here, “when the device is started from the stopped state” means both when the power is turned on and when the device is started from the preheating mode. Hereinafter, the cleaning brush 201a is also simply referred to as a brush.
[0046]
The brush rotation for the above d time is an experimental value designed to cope with the assumed worst case brush brush fall. However, the worst hair fall does not always occur, and in some cases, the influence of the hair fall can be eliminated with less rotation than d time.
Therefore, it is possible to measure the device stoppage time from the previous rotation of the brush, and change the rotation time of the brush when the power is turned on or when starting up from the preheating mode.
FIG. 6 shows the relationship between the apparatus stop time and the brush rotation time. Here, the brush rotation time is changed to four stages (d, j, i, h), but control of three stages or less or five or more stages is naturally possible.
Specifically, the relation data between the apparatus feeding time and the brush rotation time is obtained in advance by an experiment or the like (including computer simulation), and a timer (not shown) serving as an elapsed time measuring means is managed by control means (not shown) (not shown). Then, based on the measured apparatus stop time, the corresponding brush rotation number is set from the relational data table.
[0047]
Here, if only the brush is rotated while the photoconductor drum 200 is stopped, only a part of the photoconductor drum 200 is rubbed by the brush, and only this portion changes the surface state. This is of course also applicable to the case of cleaning the intermediate transfer belt 501, but in the case of the photosensitive drum 200, if the film thickness is further reduced in part, the latent image potential in that part changes and the photosensitive characteristic changes, and It appears as an upper density difference.
Therefore, at least when the brush is rotated, the photosensitive drum 200 or the intermediate transfer belt 501 that is in contact with the brush is rotated so that the brush is evenly rubbed, and this can be prevented.
[0048]
In addition, when the power is turned on, the rotation of the brush alone delays the rising time, and therefore may be performed simultaneously with the warm-up time of the fixing device 270.
Further, when performing the process control when the power is turned on, it is desirable to perform the brush rotation before this. In the process control, a patch image or the like is created, the density of the patch image is read, and the image density is adjusted. If the patch image is affected by banding or the like, the density adjustment may be out of the optimum value.
[0049]
Although the brush-like rotating body has been described above as a cleaning brush, the present invention is not limited to a cleaning brush. In other words, any brush can be used as long as it is in contact with an image carrier such as the photosensitive drum 200 or the intermediate transfer belt 501.
For example, a charging brush for charging the photosensitive drum 200, a discharging brush for removing the same, a coating brush for applying a lubricant to the image carrier (in the above example, a lubricant applying brush 505 for the intermediate transfer belt 501), and a bias are applied. And a bias application brush.
[0050]
Next, a second embodiment will be described with reference to FIG.
In the present embodiment, it is assumed that the image carrier and a rotating body such as a cleaning brush which rotates in contact with the image carrier are rotated by the same drive source. However, in the configuration shown in FIG. Since it is also applicable, only the main part will be described.
In the conventional configuration shown in FIGS. 9 and 10, a normal gear 711 is provided on a transmission shaft (drive transmission path) 713 to the cleaning fur brush 701, but in this embodiment, a one-way gear is used instead. A clutched gear 717 is provided.
In the present embodiment, control is performed to rotate the photoconductor 700 in the reverse direction when the image forming operation is not performed. When the photoreceptor 700 rotates in the reverse direction, the driving of the cleaning fur brush 701 deviates from the photoreceptor 700, and when the photoreceptor 700 rotates forward again, the position changes depending on the locked position of the one-way clutch. Pitch-shaped scratches are not formed on the photoconductor 700.
This position shifting method can be applied to other members that come into contact with the photoconductor 700, for example, a charging roller, a transfer roller, and a transfer belt. For example, this is effective when the charging roller has uneven electrical resistance in the circumferential direction.
[0051]
As shown in FIG. 8, a similar displacement function can be obtained by providing a gear 718 with a torque limiter on the transmission shaft 713 to the cleaning fur brush 701 (third embodiment). The gear 718 in this embodiment has a configuration containing a magnetic powder. With this configuration, a slip is generated between the photoconductor 700 and the photoconductor 700, and the position of the photoconductor 700 is displaced.
This position shifting method can be applied to other members that contact the photoconductor 700, for example, a charging roller. For example, this is effective when the charging roller has uneven electrical resistance in the circumferential direction. The method shown in FIG. 7 is effective in the case of a transfer belt or a transfer roller that requires positioning because of the slipping method.
[0052]
In each of the above embodiments, the tips of the cleaning brush 201a and the cleaning fur brush 701 are formed in a loop shape (see JP-A-2-149970), and the surface pressure with the image carrier is 50 g / cm. ² The above may be set. In this way, even if a small amount of transfer paper, or a discharge product generated by corona discharge or the like, adheres to the surface of the image carrier, it can be easily removed.
Further, in each of the above-described embodiments, an example has been described in which a photoconductor (photoconductor drum) is used. However, the present invention can be similarly applied to an intermediate transfer member such as an intermediate transfer belt.
[0053]
【The invention's effect】
According to the first, sixth, seventh, eighth, ninth or tenth aspect of the present invention, in an image forming apparatus having an image carrier and a brush-like rotator rotating in contact with the image carrier, the apparatus is in a stopped state. Since the brush-shaped rotator is rotated for a predetermined time when the brush-shaped rotator is started up, it is possible to prevent the occurrence of an abnormal image due to brush hair fall.
[0054]
According to the second, sixth, seventh, eighth, ninth or tenth aspect of the present invention, in the image forming apparatus of the first aspect, the rotation of the brush-like rotator is performed during a warm-up time of the apparatus. Therefore, it is not necessary to take extra time for the rotation of the brush, and it is not necessary to delay the rise time of the apparatus.
[0055]
According to the third, sixth, seventh, eighth, ninth or tenth aspect of the present invention, in the image forming apparatus according to the second aspect, the rotation of the brush-like rotator is performed more than the process control operation during the warm-up time. Since the configuration is performed before, the banding phenomenon due to brush hair fall can be prevented even in an image created at the time of process control, and highly accurate process control can be performed.
[0056]
According to the fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, when the brush-like rotator rotates, Since the image carrier is also rotated, an abnormal image due to partial rubbing can be prevented.
[0057]
According to the invention described in any one of claims 5, 6, 7, 8, 9 and 10, in the image forming apparatus according to any one of claims 1 to 4, since the brush-shaped rotator has been rotated last time. The elapsed time measuring means for measuring the elapsed time, and the predetermined time is changed in accordance with the elapsed time, so that a rotation suitable for the hair falling state can be given, and wasteful time due to extra rotation And deterioration of the brush can be prevented.
[0058]
According to the eleventh aspect of the present invention, there is provided an image carrier, and a rotating body which rotates in contact with the image carrier, and the rotating body is rotated by the same drive source as the image carrier. In the forming apparatus, since the rotation position of the image carrier is shifted from the rotating body by the reverse rotation operation of the image carrier, the image carrier can be prevented from being scratched in a pitch.
[0059]
According to the twelfth aspect of the present invention, in the image forming apparatus of the eleventh aspect, the rotational position shift is performed by a one-way clutch provided in a drive transmission path of the rotator, so that a simple configuration is provided. Thus, it is possible to prevent the image carrier from being scratched in the form of a pitch, and it is also possible to determine the position during normal rotation.
[0060]
According to the thirteenth aspect of the present invention, there is provided an image bearing member, and a rotating member which rotates in contact with the image bearing member, wherein the rotating member is rotated by the same drive source as the image bearing member. In the forming apparatus, since the rotation position of the image carrier and the rotating body is provided so as to be deviated from each other, it is possible to prevent the image carrier from being scratched in a pitch shape.
[0061]
According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, the rotational position shift is performed by a torque limiter provided in a drive transmission path of the rotating body. Accordingly, it is possible to prevent the image carrier from being scratched in a pitch shape.
[0062]
According to a fifteenth aspect of the present invention, in the image forming apparatus according to any one of the eleventh to fourteenth aspects, the rotating body is a cleaning brush, a tip of the brush is formed in a loop shape, and Surface pressure with body is 50g / cm ² With the above configuration, it is difficult to damage the surface of the image carrier, and it is easy to remove even a small amount of additives on the transfer paper, and even if a discharge product generated by corona discharge sticks to the surface of the image carrier. It becomes.
[Brief description of the drawings]
FIG. 1 is a schematic front view of a color copying machine as an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic front view of an image forming unit and a transfer unit of the color copying machine.
FIG. 3 is a diagram illustrating a hair falling state of a cleaning brush.
FIG. 4 is a graph showing the relationship between the idle time of the apparatus and the rotation fluctuation rate.
FIG. 5 is a graph showing a relationship between a brush rotation time and a rotation fluctuation rate.
FIG. 6 is a graph showing a relationship between a device stoppage time and a brush rotation time.
FIG. 7 is a perspective view of a drive configuration of a photoconductor and a cleaning brush according to a second embodiment.
FIG. 8 is a perspective view of a drive configuration of a photoconductor and a cleaning brush according to a third embodiment.
FIG. 9 is a diagram illustrating a conventional photoconductor cleaning configuration.
FIG. 10 is a perspective view of a conventional drive configuration of a photoconductor and a cleaning brush.
[Explanation of symbols]
200, 700 Photoreceptor as image carrier
201a Cleaning brush as a brush-like rotating body
701 Cleansing fur brush as rotating body

Claims (15)

In an image forming apparatus having an image carrier and a brush-like rotating body that rotates in contact with the image carrier,
An image forming apparatus, comprising: rotating the brush-like rotator for a predetermined time when the apparatus is started from a stopped state. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the rotation of the brush-like rotator is performed during a warm-up time of the apparatus. The image forming apparatus according to claim 2,
An image forming apparatus, wherein the rotation of the brush-like rotator is performed before a process control operation during the warm-up time. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus according to claim 1, wherein the image carrier is also rotated when the brush-shaped rotator is rotated. The image forming apparatus according to claim 1, wherein
An image forming apparatus, comprising: an elapsed time measuring means for measuring an elapsed time from a previous rotation of the brush-like rotating body, wherein the predetermined time is changed according to the elapsed time. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the brush-like rotating body is a cleaning brush for cleaning toner remaining on the image carrier. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the brush-like rotating body is an application brush for applying a lubricant on the image carrier. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the brush-like rotator is a bias application brush for applying a bias to the image carrier. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the brush-like rotating body is a charging brush for charging the image carrier. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the brush-like rotating member is a charge removing brush for removing charge from the image carrier. An image forming apparatus, comprising an rotator that rotates in contact with the image carrier, wherein the rotator is driven to rotate by the same drive source as the image carrier,
An image forming apparatus provided so that a rotational position shift with respect to the rotator is caused by a reverse rotation operation of the image carrier. The image forming apparatus according to claim 11,
The image forming apparatus according to claim 1, wherein the rotational position shift is performed by a one-way clutch provided in a drive transmission path of the rotating body. An image forming apparatus, comprising an rotator that rotates in contact with the image carrier, wherein the rotator is driven to rotate by the same drive source as the image carrier,
An image forming apparatus provided so as to cause a rotational position shift between the image carrier and the rotator. The image forming apparatus according to claim 13,
The image forming apparatus according to claim 1, wherein the rotational position shift is performed by a torque limiter provided in a drive transmission path of the rotating body. The image forming apparatus according to any one of claims 11 to 14,
An image forming apparatus, wherein the rotating body is a cleaning brush, a tip of the brush is formed in a loop shape, and a surface pressure with the image carrier is set to 50 g / cm ² or more.

Images