JP3943929B2 - Process means support mechanism, charging device, process cartridge, and electrophotographic image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process means support mechanism used in an electrophotographic image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, and a charging device, a process cartridge, and an image forming apparatus provided with the mechanism.
[0002]
Here, the electrophotographic image forming apparatus forms an image on the recording medium 52 using an electrophotographic image forming process.
[0003]
For example, an electrophotographic copying machine, an electrophotographic printer (such as an LED printer or a laser beam printer), an electrophotographic facsimile apparatus, and an electrophotographic word processor are included.
[0004]
Here, the process cartridge is a cartridge in which at least one of a charging unit, a developing unit, and a cleaning unit and an electrophotographic photosensitive member as an image carrier are integrally formed, and the cartridge can be attached to and detached from the image forming apparatus main body. To do.
[0005]
The charging device has means for uniformly charging the electrophotographic photosensitive member to a predetermined polarity and potential.
[0006]
[Prior art]
Conventionally, a process cartridge system in which an electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”), a charging unit, a developing unit, a cleaning unit, and the like are integrated into a cartridge and the cartridge can be attached to and detached from the image forming apparatus main body. Is adopted.
[0007]
The operability is further improved by this cartridge system, and the user can easily perform maintenance of the process means. Therefore, this cartridge system is widely used in the image forming apparatus main body.
[0008]
In addition, a cartridge configuration is realized in which the process means is divided into those having a long life and those having a short life, each process means is made into a cartridge, and can be used according to the life of the main process means. For example, a developing cartridge in which a toner storage unit and a developing unit are integrally configured, or a drum cartridge in which a photosensitive drum, a charging unit, and a cleaning unit are integrally configured are employed.
[0009]
In recent years, a developer image corresponding to image information is formed by applying an image forming process including a process of uniformly charging a photosensitive drum to a predetermined polarity and potential, and the developer image is transferred to a transfer material. The image forming product is transferred to the image forming apparatus, and the developer remaining on the photoconductive drum after the transfer process is removed and collected from the photoconductive drum by the developing means by the development simultaneous cleaning in the developing unit and reused. A cleaner-less system that eliminates the above has been proposed to provide a miniaturized image forming apparatus body.
[0010]
For example, charging of the residual transfer developer (hereinafter referred to as “transfer residual toner”) remaining on the photosensitive drum after the transfer process on the downstream side of the transfer unit and the upstream side of the charging unit in the rotation direction of the photosensitive drum. A developer charge amount control means (hereinafter referred to as “toner charge amount control means”) that aligns the polarity with the regular charge polarity is provided to prevent the transfer charging toner from adhering to the contact charging member and to prevent fogging due to charging failure, etc. A cleanerless type image forming apparatus and a process cartridge which prevent the occurrence of the above has been proposed (Japanese Patent Laid-Open No. 8-1373368).
[0011]
[Problems to be solved by the invention]
The toner charge amount control means uses a fixed, moderately conductive brush-shaped member. However, when the charge (tribo) of the transfer residual toner is controlled to an appropriate charge amount with a normal polarity, it is minimal. In some cases, overcharge of the untransferred toner occurs. When overcharge of the transfer residual toner occurs, the reflection force between the photosensitive drum and the overcharge transfer residual toner is too strong to adhere to the contact charging member, and cannot be recovered by the developing device. In this case, the toner is not transferred to the transfer material, and as a result, the overcharge transfer residual toner is fused on the photosensitive drum, leading to generation of a defective image.
[0012]
It has been found that this is caused by the fact that the fixed brush member as the toner charge amount control means continues to be located at the same position on the photosensitive drum. That is, when there is uneven resistance in the toner charge amount control means, overcharging or undercharging will always occur at the same portion on the photosensitive drum. In the overcharged portion, the above-described minimal problem of overcharging and fusing of the transfer residual toner occurs. Further, in the portion where charging is insufficient, the transfer residual toner cannot be sufficiently charged, causing a problem that the contact charging member is contaminated with toner.
[0013]
Along with the diversification of user needs in recent years, a large amount of residual toner can be transferred at one time by continuously printing images with a high printing rate, such as photographic images, or by using a multiple development system on a photoconductive drum as a result of colorization. Occurrence of the problem further promotes the above problem.
[0014]
The present invention has been made in view of the above problems, and an object of the present invention is to prevent the developer from fusing onto the surface of the photosensitive drum due to overcharge of the transfer residual toner, and to collect the transfer residual toner more effectively. The present invention provides a process means support mechanism that can be performed in a systematic manner, and a charging device, a process cartridge, and an electrophotographic image forming apparatus having the same.
[0015]
[Means for Solving the Problems]
A typical configuration according to the present invention for achieving the above object is a process means support mechanism for supporting a brush unit including two brush members that act in contact with an electrophotographic photosensitive member as a rotating body. A support member that supports the brush unit at both longitudinal ends and holds the brush member in contact with the surface of the electrophotographic photosensitive member; and the brush unit contacts the electrophotographic photosensitive member at a predetermined pressure. Biasing means for biasing the support member, and two brush portions are provided at both longitudinal ends of the brush unit, and the two shaft portions are provided on the support member. A portion of the support member facing the electrophotographic photosensitive member has an arc shape having substantially the same radius as the surface of the electrophotographic photosensitive member, and the rotation direction of the electrophotographic photosensitive member Energizing the biasing member Is positioned downstream of the midpoint of the most upstream contact position and the most downstream contact position between the arc shape of the support member and the electrophotographic photosensitive member in the rotation direction of the electrophotographic photosensitive member, and the 2 It is characterized by being between the shafts of the book.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a color electrophotographic image forming apparatus according to the present invention will be described with reference to the drawings. In the following description, the longitudinal direction is a direction perpendicular to the conveyance direction of the recording medium, and is the same direction as the axial direction of the photosensitive drum. Further, left and right are left and right as viewed from the conveyance direction of the recording medium. Further, upper and lower are upper and lower in the mounted state of the cartridge.
[0017]
[Overall Description of Image Forming Apparatus]
First, the overall configuration of the color electrophotographic image forming apparatus will be schematically described with reference to FIG.
[0018]
FIG. 1 is an explanatory diagram of the overall configuration of a color laser beam printer which is an embodiment of a color toner image forming apparatus.
[0019]
The image forming unit of the color laser beam printer includes four process cartridges 1Y, 1M, 1C, and 1K (yellow, magenta, cyan, and black) each including a photosensitive drum 2 that is an image carrier. Above the process cartridges 1Y, 1M, 1C, and 1K, exposure means 51Y, 51M, 51C, and 51K (laser beam optical scanning systems) corresponding to the respective colors are arranged in parallel.
[0020]
Below the image forming section, a feeding means for feeding the recording medium 52, an intermediate transfer belt 54a for transferring a toner image formed on the photosensitive drum 2, and a toner image on the intermediate transfer belt 54a are recorded. A secondary transfer roller 54d for transferring to 52 is disposed.
[0021]
Further, fixing means for fixing the recording medium 52 to which the toner image has been transferred, and discharging means for discharging and stacking the recording medium 52 outside the apparatus are arranged.
[0022]
Here, the recording medium 52 is, for example, paper, an OHP sheet, or cloth.
[0023]
The image forming apparatus of the present embodiment is an apparatus of a cleaner-less system. The transfer residual toner remaining on the photosensitive drum 2 is taken into the developing means, and a dedicated cleaner for collecting and storing the transfer residual toner is contained in the process cartridge. Is not arranged.
[0024]
Next, the configuration of each part of the image forming apparatus will be sequentially described in detail.
[0025]
[Paper Feeder]
The paper feeding unit feeds the recording medium 52 to the image forming unit. The paper feeding unit 53a stacks and stores a plurality of recording media 52, the feeding roller 53b, the double feed preventing retard roller 53c, the feeding roller 53b. It is mainly composed of a feed guide 53d and a registration roller 53g.
[0026]
The feeding roller 53b is driven and rotated according to the image forming operation, and separates and feeds the recording medium 52 in the feeding cassette 53a one by one. The recording medium 52 is guided by the feeding guide 53d and is conveyed to the registration roller 53g via the conveyance rollers 53e and 53f.
[0027]
Immediately after the recording medium 52 is conveyed, the registration roller 53g stops rotating, and the recording medium 52 is corrected to be skewed by hitting the nip portion.
[0028]
During the image forming operation, the registration roller 53g performs a non-rotating operation for causing the recording medium 52 to stand still and a rotating operation for conveying the recording medium 52 toward the intermediate transfer belt 54a in a predetermined sequence. The toner image and the recording medium 52 in a certain transfer process are aligned.
[0029]
[Process cartridge]
The process cartridges 1Y, 1M, 1C, and 1K are configured integrally by arranging a charging unit and a developing unit around a photosensitive drum 2 that is an image carrier. This process cartridge can be easily removed from the apparatus main body by the user and replaced when the photosensitive drum 2 reaches the end of its life.
[0030]
In the present embodiment, for example, the number of rotations of the photosensitive drum 2 is counted, and when the predetermined count number is exceeded, the fact that the process cartridge has reached the end of life is notified.
[0031]
The photosensitive drum 2 of the present embodiment is a negatively charged organic photosensitive member, and has a commonly used photosensitive layer on an aluminum drum base having a diameter of about 30 mm, and a charge injection layer is provided on the outermost layer. Yes. Then, it is rotationally driven at a predetermined process speed, in this embodiment, about 117 mm / sec.
[0032]
The charge injection layer uses a coating layer made of a material in which, for example, SnO ₂ ultrafine particles are dispersed as conductive fine particles in an insulating resin binder.
[0033]
As shown in FIG. 4, a drum flange 2b is fixed to the back end portion of the photosensitive drum 2, and a non-drive flange 2d is fixed to the front end portion. The drum shaft 2a passes through the center of the drum flange 2b and the non-drive flange 2d, and the drum shaft 2a, the drum flange 2b, and the non-drive flange 2d are rotated together. That is, the photosensitive drum 2 is rotated around the axis of the drum shaft 2a.
[0034]
The front end of the drum shaft 2a is rotatably supported by the bearing 2e, and the bearing 2e is fixed to the bearing case 2c. The bearing case 2c is fixed to the frame of the process cartridge.
[0035]
[Charging means]
The charging means as the charging device uses a contact charging method. In the present embodiment, the charging roller 3a is used as the charging member.
[0036]
As shown in FIG. 2, the charging roller 3a holds both ends of the cored bar 3b rotatably by bearing members (not shown), and is urged toward the photosensitive drum by a pressing spring 3d so as to be photosensitive drum 2. Is pressed against the surface of the photosensitive drum 2 with a predetermined pressing force, and is rotated by the rotation of the photosensitive drum 2.
[0037]
Reference numeral 3c denotes a charging roller cleaning unit, which is cleaned by a flexible cleaning film 3e in this embodiment. The cleaning film 3e is arranged in parallel with the longitudinal direction of the charging roller 3a, and one end side is fixed to a support member 3f that reciprocates a certain amount in the longitudinal direction. It is arranged to form a contact nip.
[0038]
The supporting member 3f is reciprocated by a predetermined amount in the longitudinal direction by a driving means (not shown), and the surface of the charging roller is rubbed with the cleaning film 3e. As a result, deposits on the surface of the charging roller (fine powder toner, external additives, etc.) are removed.
[0039]
[Cleanerless system]
The image forming apparatus of this embodiment employs a cleanerless system. This cleanerless system will be described.
[0040]
The outline of the cleanerless system in the image forming apparatus according to the present embodiment will be described first. In FIG. 2, the transfer residual toner on the photosensitive drum 2 after the transfer is charged with the charging unit a and the exposure as the photosensitive drum 2 continues to rotate. The part b is passed through and carried to the developing part c, and is simultaneously cleaned (collected) by the developing device.
[0041]
Since the untransferred toner on the surface of the photosensitive drum 2 passes through the exposure portion b, the exposure process is performed from the untransferred toner. However, since the amount of the untransferred toner is small, no significant influence appears.
[0042]
However, the transfer residual toner includes normal polarity, reverse polarity (reversal toner), and low charge amount, and when the reverse toner or the low charge amount toner passes through the charging portion a. As a result of adhering to the charging roller 3a, the charging roller 3a contaminates the toner more than permissible, resulting in poor charging.
[0043]
In addition, in order to effectively perform the simultaneous development cleaning of the transfer residual toner on the surface of the photosensitive drum by the developing device, the charging polarity of the transfer residual toner on the photosensitive drum carried to the developing unit c is a normal polarity. In addition, the charge amount needs to be a charge amount that can develop the electrostatic latent image on the photosensitive drum by the developing device. That is, reversal toner and toner with an inappropriate charge amount cannot be removed and collected from the photosensitive drum to the developing device, causing a defective image.
[0044]
In addition, with the diversification of user needs in recent years, a large amount of untransferred toner is generated at a time due to continuous printing operations such as images with a high printing rate such as photographic images, which further promote the above-described problems. It is.
[0045]
Therefore, in this embodiment, in order to efficiently collect the transfer residual toner, a transfer residual toner equalizing unit 3g and a toner charge control unit 3h are provided as process units that act in contact with the photosensitive drum 2. That is, a transfer residual toner (residual developer image) equalizing means 3g for uniformizing the transfer residual toner on the photoconductive drum 2 is provided at a position downstream of the transfer portion d in the rotation of the photoconductive drum 2. In order to align the charging polarity of the residual toner to the negative polarity that is the normal polarity at the position downstream of the photosensitive drum rotation direction with respect to the transfer residual toner uniformizing means 3g and at the upstream side of the charging portion a with respect to the photosensitive drum rotation direction. The toner (developer) charge control means 3h is provided.
[0046]
By providing the transfer residual toner uniformizing means 3g, even if the amount of toner remaining on the pattern on the photosensitive drum carried from the transfer portion d to the toner charging control means 3h is large, the toner remains on the photosensitive drum. Since the surface is distributed and non-patterned, the toner does not concentrate on a part of the toner charge control means 3h. For this reason, the entire normal polarity charging process of the transfer residual toner by the toner charge control means 3h is always sufficiently performed, and the adhesion of the transfer residual toner to the charging roller 3a is effectively prevented. Further, the occurrence of a ghost image of the transfer residual toner image pattern is also prevented.
[0047]
In the present embodiment, the transfer residual toner uniformizing means 3g and the toner charge control means 3h are brush-like members having appropriate conductivity, and are arranged in contact with the surface of the photosensitive drum.
[0048]
These means are moved (reciprocated) in the longitudinal direction of the photosensitive drum by a driving source (not shown). By doing so, the transfer residual toner equalizing means 3g and the toner charge control means 3h do not continue to be located at the same place on the photosensitive drum. For example, an overcharge portion caused by uneven resistance of the toner charge control means 3h, Even if there is an insufficiently charged part, it does not always occur on the same surface of the photoconductive drum. Therefore, over-charging of the minimal transfer residual toner causes fusion on the photoconductive drum, and charging due to insufficient charging. The transfer residual toner is prevented or mitigated from adhering to the roller 3a.
[0049]
[Exposure means]
In the present embodiment, the exposure to the photosensitive drum 2 is performed using laser exposure means. That is, when an image signal is sent from the apparatus main body, the laser beam L modulated in accordance with this signal is scanned and exposed on the uniformly charged surface of the photosensitive drum 2. An electrostatic latent image corresponding to the image information is selectively formed on the surface of the photosensitive drum 2.
[0050]
As shown in FIG. 1, the laser exposure means includes a solid-state laser element (not shown), a polygon mirror 51a, an imaging lens 51b, a reflection mirror 51c, and the like. Based on the input image signal, the solid-state laser element is controlled to emit light ON / OFF at a predetermined timing by a light emission signal generator (not shown). Laser light L emitted from the solid-state laser element is converted into a substantially parallel light beam by a collimator lens system (not shown) and scanned by a polygon mirror 51a that rotates at high speed. Then, an image is formed in a spot shape on the photosensitive drum 2 via the imaging lens 51b and the reflection mirror 51c.
[0051]
Thus, on the surface of the photosensitive drum 2, exposure in the main scanning direction by laser light scanning and further exposure in the sub-scanning direction by rotating the photosensitive drum 2 are performed, and an exposure distribution according to the image signal is obtained. It is done.
[0052]
That is, a bright portion potential with a lowered surface potential and a dark portion potential with no surface potential are formed by irradiation and non-irradiation of the laser beam L. An electrostatic latent image corresponding to the image information is formed by the contrast between the bright part potential and the dark part potential.
[0053]
[Development means]
The developing device 4 that is a developing means is a two-component contact developing device (two-component magnetic brush developing device), and as shown in FIG. 2, a carrier is placed on a developing sleeve 4a that is a developer carrying member including a magnet roller 4b. And a developer composed of toner. The developing sleeve 4a is provided with a regulating blade 4c having a predetermined gap, and a thin layer of developer is formed on the developing sleeve 4a as the developing sleeve 4a rotates in the arrow direction.
[0054]
As shown in FIG. 4, the developing sleeve 4a is disposed so as to have a predetermined gap with the photosensitive drum 2 by rotatably engaging the spacer 4k with the reduced diameter journal portions 4a1 on both sides thereof. Is set so that the developer formed on the developing sleeve 4a can be developed in contact with the photosensitive drum 2. The developing sleeve 4a is driven to rotate at a predetermined peripheral speed in a clockwise direction indicated by an arrow that is a counter direction with respect to the rotation direction of the photosensitive drum 2 in the developing unit.
[0055]
The toner used in this embodiment is a negatively charged toner having an average particle diameter of 6 μm, and a magnetic carrier having an average particle diameter of 35 μm having a saturation magnetization of 205 emu / cm ³ is used as the magnetic carrier. Also, a toner and carrier mixed at a weight ratio of 6:94 is used as a developer.
[0056]
The developer accommodating portion 4h in which the developer circulates is divided into two by a longitudinal partition 4d except for both ends. And stirring screw 4eA, 4eB is arrange | positioned on both sides of this partition 4d.
[0057]
As shown in FIG. 4, the toner replenished from the toner replenishing container falls to the back side of the agitating screw 4eB, is agitated while being sent to the front side in the longitudinal direction, and passes through a portion without the partition 4d at the front end. Then, it is further fed to the far side in the longitudinal direction by the stirring screw 4eA, passes through a portion without the partition 4d on the far side, is stirred while being fed by the stirring screw 4eB, and is repeatedly circulated.
[0058]
Here, a developing process for visualizing the electrostatic latent image formed on the photosensitive drum 2 by the two-component magnetic brush method using the developing device 4 and a developer circulation system will be described.
[0059]
With the rotation of the developing sleeve 4a, the developer in the developing container is pumped to the surface of the developing sleeve 4a by the pumping pole of the magnet roller 4b and conveyed.
[0060]
In the process of being conveyed, the layer thickness of the developer is regulated by a regulating blade 4c arranged perpendicular to the developing sleeve 4a, and a thin layer developer is formed on the developing sleeve 4a. When the thin layer developer is transported to the developing pole corresponding to the developing portion, a spike is formed by the magnetic force. The electrostatic latent image on the surface of the photosensitive drum 2 is developed as a toner image by the toner in the developer formed in the spike shape. In this embodiment, the electrostatic latent image is reversely developed.
[0061]
The thin-layer developer on the developing sleeve 4a that has passed through the developing portion continues to enter the developing container as the developing sleeve 4a rotates, and is separated from the developing sleeve 4a by the repulsive magnetic field of the transport pole, and the developer pool in the developing container is retained. Returned to
[0062]
A direct current (DC) voltage and an alternating current (AC) voltage are applied to the developing sleeve 4a from a power source (not shown). In this embodiment, a DC voltage of −500 V and an AC voltage of a peak-to-peak voltage of 1500 V at a frequency of 2000 Hz are applied, and only the exposed portion of the photosensitive drum 2 is selectively developed.
[0063]
In general, in the two-component development method, when an AC voltage is applied, the development efficiency increases and the image becomes high-quality, but conversely, there is a risk that fogging easily occurs. For this reason, in general, it is possible to prevent fogging by providing a potential difference between the DC voltage applied to the developing sleeve 4 a and the surface potential of the photosensitive drum 2. More specifically, a bias voltage having a potential between the potential of the exposed portion of the photosensitive drum 2 and the potential of the non-exposed portion is applied.
[0064]
When the toner is consumed by development, the toner concentration in the developer decreases. In the present embodiment, a density sensor 4g that detects the toner density is disposed at a position close to the outer peripheral surface of the stirring screw 4eB. When the sensor 4g detects that the toner density in the developer has dropped below a predetermined density level, a command to replenish toner into the developing device 4 is issued from the toner replenishing container. By this toner replenishment operation, the toner density of the developer is always maintained at a predetermined level.
[0065]
[Toner supply container]
The toner supply containers 5Y, 5M, 5C, and 5K are arranged in parallel above the process cartridges 1Y, 1M, 1C, and 1K, and are mounted from the front of the apparatus main body 100.
[0066]
As shown in FIG. 2, a stirring plate 5b fixed to the stirring shaft 5c and a screw 5a are disposed inside the toner supply container, and a discharge opening 5f for discharging the toner is formed on the bottom of the container.
[0067]
As shown in FIG. 5, the screw 5a and the stirring shaft 5c are rotatably supported by bearings 5d at both ends, and a drive coupling (concave) 5e is disposed at one end. This drive coupling (concave) 5e receives drive transmission from the drive coupling (convex) 62b of the apparatus body and is driven to rotate. The outer shape of the screw 5a has a spiral rib shape, and the twisting direction of the spiral is reversed around the discharge opening 5f. The screw 5a is rotated in a predetermined rotation direction by the rotation of the drive coupling (convex) 62b. Then, the toner is conveyed toward the discharge opening 5f, the toner is freely dropped from the opening of the discharge opening 5f, and the process cartridge is replenished. The tip of the stirring plate 5b in the rotational radius direction is inclined, and the tip is brought into contact with the wall of the toner supply container at a certain angle. Specifically, the tip end side of the stirring plate 5b is twisted to become a spiral state. In this way, the tip end side of the stirring plate 5b is twisted and inclined to generate an axial conveying force, and the toner is sent in the longitudinal direction.
[0068]
The toner replenishing container of the present embodiment is not limited to the two-component developing method, and can be replenished in a process cartridge or a developing cartridge using the one-component developing method, and the powder stored in the toner replenishing container is: Needless to say, the developer is not limited to the toner but may be a so-called developer in which the toner and the magnetic carrier are mixed.
[0069]
[Transfer means]
The intermediate transfer unit 54 serving as a transfer unit is a unit that collectively transfers a plurality of toner images that are sequentially primary-transferred from the photosensitive drum 2 and superimposed on the recording medium 52.
[0070]
The intermediate transfer unit 54 includes an intermediate transfer belt 54a that runs in the direction of the arrow, and runs in the clockwise direction indicated by the arrow in FIG. The intermediate transfer belt 54a is an endless belt having a circumferential length of about 940 mm, and is stretched around three rollers: a driving roller 54b, a secondary transfer counter roller 54g, and a driven roller 54c.
[0071]
Further, in the intermediate transfer belt 54a, transfer charging rollers 54fY, 54fM, 54fC, and 54fK are rotatably disposed at positions opposed to the photosensitive drum 2, and are pressed toward the center of the photosensitive drum 2.
[0072]
The transfer charging rollers 54fY, 54fM, 54fC, and 54fK are supplied with power from a high voltage power supply (not shown), and are charged with the opposite polarity to the toner from the back side of the intermediate transfer belt 54a, and sequentially transfer the toner images on the photosensitive drum 2 to the intermediate transfer belt 54a. Primary transfer is performed on the upper surface.
[0073]
In the secondary transfer portion, a secondary transfer roller 54d as a transfer member is pressed against the intermediate transfer belt 54a at a position facing the secondary transfer counter roller 54g. The secondary transfer roller 54d can swing up and down in the drawing and rotates. At the same time, since a bias is applied to the intermediate transfer belt 54a, the toner image on the intermediate transfer belt 54a is transferred to the recording medium 52.
[0074]
Here, the intermediate transfer belt 54a and the secondary transfer roller 54d are each driven. When the recording medium 52 enters the secondary transfer portion, a predetermined bias is applied to the secondary transfer roller 54d, and the toner image on the intermediate transfer belt 54a is secondarily transferred to the recording medium 52.
[0075]
At this time, the recording medium 52 sandwiched between the two is transported at a predetermined speed in the left direction in FIG. 1 at the same time as the transfer process, and is transported toward the fixing unit 56 as the next process.
[0076]
At a predetermined position of the intermediate transfer belt 54a, which is the most downstream side of the transfer process, a cleaning unit 55 that can come in contact with and separate from the surface of the intermediate transfer belt 54a is provided to remove transfer residual toner remaining after the secondary transfer.
[0077]
In the cleaning unit 55, a cleaning blade 55a for removing transfer residual toner is disposed. The cleaning unit 55 is mounted so as to be able to swing at a rotation center (not shown), and the cleaning blade 55a is in pressure contact with the intermediate transfer belt 54a. The transfer residual toner taken into the cleaning unit 55 is conveyed and stored in a waste toner tank (not shown) by the feed screw 55b.
[0078]
Here, as the intermediate transfer belt 54a, a belt made of polyimide resin can be used. Other materials are not limited to polyimide resin, but plastics such as polycarbonate resin, polyethylene terephthalate resin, polyvinylidene fluoride resin, polyethylene naphthalate resin, polyether ether ketone resin, polyether sulfone resin, polyurethane resin, etc. Fluorine-based or silicon-based rubber can be preferably used [fixing part]
The toner image formed on the photosensitive drum 2 by the developing means is transferred onto the recording medium 52 via the intermediate transfer belt 54a. The fixing device 56 fixes the toner image transferred to the recording medium 52 to the recording medium 52 using heat.
[0079]
As shown in FIG. 1, the fixing device 56 includes a fixing roller 56a for applying heat to the recording medium 52 and a pressure roller 56b for pressing the recording medium 52 against the fixing roller 56a. 56b is a hollow roller. Each of them has a heater (not shown). Then, the recording medium 52 is simultaneously conveyed by being driven to rotate.
[0080]
That is, the recording medium 52 holding the toner image is conveyed by the fixing roller 56a and the pressure roller 56b, and the toner image is fixed to the recording medium 52 by applying heat and pressure. The recording medium 52 after fixing is discharged by discharge rollers 53h and 53j and is loaded on a tray 57 on the apparatus main body 100.
[0081]
[Installation of process cartridge and toner supply container]
Next, the mounting procedure of the process cartridge and the toner supply container will be described with reference to FIGS. 2, 3, 4, and 5. FIG.
[0082]
As shown in FIG. 3, a front door 58 that can be opened and closed is disposed on the front surface of the apparatus main body 100. When the front door 58 is opened to the front, an opening for inserting a process cartridge and a toner supply container is exposed. Is done.
[0083]
A centering plate 59 that is rotatably supported is disposed in the opening for inserting the process cartridge. When the process cartridge is inserted and removed, the centering plate 59 is opened.
[0084]
In the apparatus main body 100, as shown in FIG. 2, a guide rail 60 for guiding the mounting of the process cartridge and a guide rail 61 for guiding the mounting of the toner supply container are fixed.
[0085]
The mounting direction of the process cartridge and the toner supply container is a direction parallel to the axial direction of the photosensitive drum 2, and the guide rails 60 and 61 are also arranged in the same direction. The process cartridge and the toner supply container are once slid along the guide rails 60 and 61 from the front side in the apparatus main body 100 to the back side.
[0086]
When the process cartridge is inserted to the innermost part, as shown in FIG. 4, the centering shaft 66 of the apparatus main body is inserted into the center hole 2f of the drum flange 2b, and the rotation center position on the back side of the photosensitive drum 2 is set. Determined for the device body. At the same time, the drive transmission portion 2g formed on the drum flange 2b and the drive coupling (convex) 62a are connected, and the photosensitive drum 2 can be rotationally driven.
[0087]
The drive transmission unit 2g used in the present embodiment has a twisted triangular prism shape, and a drive force is transmitted by applying a drive force from the main body, and a force for pulling the photosensitive drum 2 to the back side is generated. Yes.
[0088]
Further, a support pin 63 for positioning the process cartridge is disposed on the rear side plate 65. The support pin 63 is inserted into the frame of the process cartridge, and the position of the frame of the process cartridge is fixed.
[0089]
A rotatable centering plate 59 is disposed on the front side of the apparatus main body 100, and the bearing case 2c of the process cartridge is supported and fixed to the centering plate 59. By this series of insertion operations, the photosensitive drum 2 and the process cartridge are positioned with respect to the apparatus main body.
[0090]
On the other hand, when the toner supply container is inserted to the innermost part, it is fixed to the support pin 64 protruding from the rear side plate 65 as shown in FIG. At the same time, the drive coupling (concave) 5e and the drive coupling (convex) 62b are connected, and the screw 5a and the stirring shaft 5c can be driven to rotate.
[0091]
[Brush unit configuration of charging means]
Next, the brush unit configuration of the charging means of the present invention will be described with reference to FIGS. 6 is a schematic perspective view of the charging means adopting the cleanerless system, FIG. 7 is a schematic sectional view of the charging means, FIG. 8 is a schematic front view of the charging means, and FIG. 10 is a schematic top view of the brush unit of the charging means, FIG. 11 is an explanatory diagram of the urging position of the brush unit, and FIG. 12 is a schematic explanatory diagram of the force acting on the brush unit.
[0092]
As shown in FIG. 7, the brush unit 3j in which the transfer residual toner uniformizing means 3g and the toner charge amount control means 3h are unitized supports and fixes the transfer residual toner uniformizing means 3g to the brush base 11a. Is fixed to the base frame 12 made of sheet metal by heat-clamping, screw-fastening, double-sided tape, etc. Similarly, the toner charge amount control means 3h is fixedly supported on the brush base 11b, and this brush base 11b is attached to the base frame 12. It is a unit that is fixedly configured.
[0093]
As shown in FIG. 8, shafts 13a, 13b, 13c, and 13d extend from both ends of the base frame 12, and a transmission arm member 14 is attached to the shafts 13a and 13b on one side (drive side). . The transfer residual toner equalizing means 3g and the toner charge amount control means 3h are arranged at an angle so as to be in a state toward the center of the photosensitive drum 2.
[0094]
As described above, the brush unit 3j has the transfer residual toner equalizing unit 3g and the toner charge amount control unit 3g and the toner charge amount control unit 3h attached to and integrated with the base frame 12, respectively. The means 3h is a unit that is used so that the front ends thereof are in contact with the surface of the photosensitive drum 2.
[0095]
(Brush unit drive configuration)
As shown in FIG. 8, the charging means 3 has a coupling gear 15 and a reciprocating cam 16 as drive transmission means on one end side in the longitudinal direction, and is rotatably fitted and supported on the frame 3k of the charging means 3. . The reciprocating cam 16 includes a cam gear 16a and a cam 16b that mesh with the coupling gear 15. A cam groove 16c is formed by the cam gear 16a and the cam 16b, and is connected to rotate together. The protruding portion 14a of the transmission arm member 14 of the brush unit 3j is fitted in the cam groove 16c. When mounted on the main body of the image forming apparatus, a main body coupler (not shown) is engaged with the coupling gear 15, a rotational driving force is transmitted, and the reciprocating cam 16 engaged with the coupling gear 15 rotates.
[0096]
When the reciprocating cam 16 rotates, the transmission arm member protrusion 14a of the brush unit 3j fitted in the cam groove 16c is moved in the longitudinal direction along the cam groove 16c, and reciprocates. In this embodiment, the reciprocating motion is performed at a constant cycle within a range of about 0.5 to 2.5 seconds with a stroke of 5 mm.
[0097]
(Brush unit support / brush penetration)
In the brush unit 3j described above, the transfer residual toner uniformizing means 3g and the toner charge amount control means 3h, which are brush-like members, are directed toward the center of the photosensitive drum 2 with respect to the surface of the photosensitive drum 2. The brush tip must be supported on the surface of the drum 2 so as to have predetermined penetration amounts X1 and X2. When the predetermined intrusion amounts X1 and X2 are not satisfied, for example, when the intrusion amount is small, the transfer residual toner easily slips through the transfer residual toner uniformizing means 3g and the toner charge amount control means 3h, and each of them is not sufficiently charged. Unevenness occurs in the charge amount of the transfer residual toner. If the amount of intrusion is large, the transfer residual toner uniformizing means 3g and the toner charge amount control means 3h increase the contact pressure with the photosensitive drum 2, excessively clogging the residual transfer toner, and scraping off the surface of the photosensitive drum 2. There is a risk that.
[0098]
Similarly, if the posture of the transfer residual toner uniformizing means 3g and the toner charge amount control means 3h is not in the state of being directed toward the center of the photosensitive drum 2, the predetermined amount of intrusion will be lost. On the other hand, the toner is positively brought into contact with the surface of the photosensitive drum 2 in a counter state, and the transfer residual toner on the surface of the photosensitive drum 2 is scraped off.
[0099]
Therefore, in the present embodiment, the postures of the transfer residual toner uniformizing unit 3g and the toner charge amount control unit 3h are held in the state of being directed toward the center of the photosensitive drum 2, and the intrusion amount of the brush tip is a predetermined intrusion amount. Support members are provided to control X1 and X2.
[0100]
Specifically, as shown in FIG. 9, the spacer 17 as a support member has an arc-shaped portion 17c similar to the surface of the photosensitive drum 2 on the surface, and has a determination hole 17a and an oblong hole 17b. It is a resin member. For example, a resin excellent in slidability such as polyacetal resin (POM), polyfinylene sulfide (PPS), and polyamide resin (nylon) is preferable. The fixed hole 17a and the oblong hole 17b of the spacer 17 are fitted to each of two shafts 13a, 13b, 13c, 13d extending to both ends of the base frame 12 of the brush unit 3j so as to be slidable in the longitudinal direction. The brush unit 3j is restricted from rotating with respect to the spacer 17, and the posture and position are determined. The brush unit 3j is biased by a compression coil spring 18 serving as a biasing means, and spacers 17 fitted to both ends abut against the surface of the photosensitive drum 2 with a predetermined pressure. In this embodiment, the compression coil spring 18 is attached to a spacer 17 fitted to both ends of the brush unit 3j, and directly urges the spacer 17 itself supporting the brush unit 3j.
[0101]
As shown in FIG. 9, the spacer 17 is regulated by the guide portion 3 m provided at a predetermined position in the longitudinal direction of the frame 3 k of the charging unit 3, and the position is regulated in the longitudinal direction and the guide 3 m in the direction of the photosensitive drum 2. A compression coil spring 18 is located between the frame 3k of the charging means 3 and the spacer 17.
[0102]
Since the spacer 17 does not reciprocate in the longitudinal direction with respect to the photosensitive drum 2, by directly biasing the spacer 17, the brush unit 3j can be stably biased to the photosensitive drum 2 regardless of the reciprocating motion. .
[0103]
(Pressurization of spacer)
As shown in FIG. 12, the transfer residual toner uniformizing means 3g and the toner charge amount control means 3h are in contact with the photosensitive drum 2, thereby generating repulsive forces F1 and F2, respectively. Further, when the photosensitive drum 2 rotates, sliding frictional forces F3 and F4 in the rotation direction are generated. As a result, a moment M due to F1, F2, F3, and F4 acts on the brush unit 3j when the photosensitive drum 2 rotates, and a force that tilts the posture with respect to the surface of the photosensitive drum 2 acts.
[0104]
Since the spacer 17 supports the brush unit 3j, as a result, as shown in FIG. 12B, the upstream portion P of the arc-shaped portion 17c in the rotational direction of the photosensitive drum is in contact with the photosensitive drum 2, but is photosensitive. The downstream Q portion in the rotation direction of the body drum 2 tends to be separated from the surface of the photoreceptor drum 2.
[0105]
Therefore, in the present embodiment, as shown in FIG. 11, the position of the spacer 17 urged by the compression coil spring 18 is set to the midpoint between the contact portions P and Q with the photosensitive drum 2 (when there are a plurality of contact portions). In this case, the position (W) is shifted to the downstream side in the rotation direction of the photosensitive drum 2 from the most upstream contact position in the rotation direction of the photosensitive drum 2 to the middle of the most downstream contact position. As a result, even if the moment M generated from the repulsive forces F1 and F2 and the frictional forces F3 and F4 caused by the rotation and sliding of the photosensitive drum 2 occurs, the contact portions P and Q of the arc-shaped portion 17c of the spacer 17 become the photosensitive drum. It is made to contact | abut to the surface of 2. By shifting the position where the pressure is applied by the compression spring 18 in this way, the vector direction of the force acting on the brush unit 3j and the pressure force of the compression spring 18 can be balanced, and the urging force of the compression spring 18 can be strengthened and exposed. Without excessively pressing the body drum 2, the posture of the brush unit 3j can be maintained and the amount of intrusion can be supported appropriately.
[0106]
As a result, the brush unit 3j is positioned at a predetermined distance from the surface of the photosensitive drum 2 while being maintained in the posture by the spacer 17. In other words, the brush tip of the transfer residual toner uniformizing means 3g and the brush tip of the toner charge amount control means 3h are kept at predetermined positions and predetermined penetration amounts X1 and X2 with respect to the surface of the photosensitive drum 2.
[0107]
In addition, each brush tip part penetration | invasion amount X1, X2 has preferable 0.5-2.5 mm, and the spacer shape used as 1.5 mm penetration | invasion is employ | adopted in this embodiment. The compression coil spring 18 preferably has a spring pressure in the range of 4.9035 N (0.5 kgf) to 19.614 N (2 kgf). In this embodiment, the spring pressure is 9.807 N (1 kgf).
[0108]
With the above configuration, when the brush unit 3j according to the present embodiment is driven from the main body of the image forming apparatus, the spacer 17 is in contact with the surface of the photosensitive drum 2 with a predetermined pressure, and the photosensitive member of the brush unit 3j. The two shafts 13a, 13b, 13c and 13d extending to both ends of the brush unit 3j are thrust in the longitudinal direction with respect to the spacer determining hole 17a and the oblong hole 17b while maintaining the posture with respect to the drum 2. The brush unit 3j reciprocates as described above.
[0109]
In the embodiment described above, the two brush members of the transfer residual toner uniformizing means 3g and the toner charge control means 3h are exemplified as the process means acting in contact with the photosensitive drum 2. However, the process means is limited to the brush member. It is not necessary and may be a single member.
[0110]
【The invention's effect】
As described above, according to the present invention, the repulsive force received from the electrophotographic photosensitive member and the repulsive force received from the electrophotographic photosensitive member can be reduced by setting the biasing force of the supporting member that supports the brush unit acting in contact with the electrophotographic photosensitive member to a predetermined position. Even if there is a moment generated from the frictional force received from the rotational sliding, the urging of the brush unit to the surface of the electrophotographic photosensitive member can be stabilized.
[0111]
Further, since it is not necessary to increase the urging force for stabilizing the contact of the brush unit , the posture can be maintained without applying excessive pressure to the electrophotographic photosensitive member.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an image forming apparatus main body.
FIG. 2 is a cross-sectional view of a process cartridge and a toner supply container.
FIG. 3 is a schematic perspective view of an image forming apparatus main body.
FIG. 4 is a longitudinal sectional view of a process cartridge.
FIG. 5 is a longitudinal sectional view of a toner supply container.
FIG. 6 is a schematic perspective view of charging means adopting a cleaner-less system.
FIG. 7 is a schematic sectional view of a charging unit.
FIG. 8 is a schematic front view of a charging unit.
FIG. 9 is a schematic side view of a charging unit.
FIG. 10 is a schematic top view of a brush unit of charging means.
FIG. 11 is an explanatory diagram of an urging position of the brush unit.
FIG. 12 is a schematic explanatory diagram of forces acting on the brush unit.
[Explanation of symbols]
L ... Laser beams 1Y, 1M, 1C, 1K ... Process cartridge 2 ... Photoconductor drum 2a ... Drum shaft 2b ... Drum flange 2c ... Bearing case 2d ... Non-driving flange 2e ... Bearing 2f ... Center hole 2g ... Drive transmission section 3 ... Charging means 3a ... charging roller 3b ... core metal 3c ... charging roller cleaning unit 3d ... spring 3e ... cleaning film 3f ... support member 3g ... transfer residual toner uniformizing means 3h ... toner charge control means 3j ... brush unit 3k ... frame 3m ... Guide section 4a ... developing sleeve 4a1 ... journal section 4b ... magnet roller 4c ... regulating blade 4d ... partition 4eA, 4eB ... stirring screw 4g ... concentration sensor 4h ... developer storage section 4k ... spacers 5Y, 5M, 5C, 5K ... toner supply Container 5a ... Screw 5b ... Stirring plate 5c ...拌軸 5d ... bearing 5e ... drive coupling 5f ... discharge opening
11a ... brush stand
11b ... brush stand
12… Base frame
13a, 13b, 13c, 13d ... axis
14… Transmission arm member
14a ... Projection
15… Coupling gear
16… Reciprocating cam
16a ... Cam gear
16b ... cam
16c… Cam groove
17… Spacer
17a… Decision hole
17b ... oblong hole
17c ... Arc shape part
18… compression coil spring
51Y, 51M, 51C, 51K ... Exposure means
51a Polygon mirror
51b ... Imaging lens
51c ... Reflection mirror
52… Recording media
53a ... Feed cassette
53b ... Feed roller
53c ... retard roller
53d ... Feeding guide
53e, 53f ... Conveyance roller
53g ... Registration roller
53h, 53j ... discharge roller
54… Intermediate transfer unit
54a ... Intermediate transfer belt
54b ... Driving roller
54c… driven roller
54d ... Secondary transfer roller
54fY, 54fM, 54fC, 54fK ... Transfer charging roller
54g ... Secondary transfer counter roller
55… Cleaning unit
55a ... Cleaning blade
56… Fixer
56a: Fixing roller
56b… Pressure roller
57… Tray
58… Front door
59… Centering plate
60, 61 ... guide rail
62b ... Drive coupling
63, 64… support pins
65… Rear side plate
66… Centering axis
100 ... Main unit

Claims (6)

A process means support mechanism for supporting a brush unit comprising two brush members acting in contact with an electrophotographic photosensitive member as a rotating body,
A support member that supports the brush unit at both ends in the longitudinal direction and holds the posture so that the brush member contacts the surface of the electrophotographic photosensitive member;
Biasing means for biasing the support member so that the brush unit contacts the electrophotographic photosensitive member at a predetermined pressure;
The brush unit includes two shaft portions at both ends in the longitudinal direction,
Each of the two shaft portions is fitted with a hole provided in the support member,
A portion of the support member facing the electrophotographic photosensitive member has an arc shape having substantially the same radius as the surface of the electrophotographic photosensitive member,
The biasing position of the biasing member in the rotation direction of the electrophotographic photosensitive member is a midpoint between the most upstream contact position and the most downstream contact position between the arc shape of the support member and the electrophotographic photosensitive member. A process means supporting mechanism, further comprising a downstream side in the rotation direction of the electrophotographic photosensitive member and between the two shaft portions.   2. The process according to claim 1, wherein the support member holds the brush tip so that a brush tip of the brush member has a predetermined penetration amount with respect to the surface of the electrophotographic photosensitive member toward the rotation center of the electrophotographic photosensitive member. Means support mechanism. In a charging device for charging an electrophotographic photosensitive member as a rotating body,
A charging roller for charging the electrophotographic photosensitive member; and a brush unit including two brush members that act in contact with the electrophotographic photosensitive member;
A charging device, wherein the brush unit is supported by the process means support mechanism according to claim 1. In a process cartridge detachable from the image forming apparatus main body,
An electrophotographic photoreceptor as a rotating body;
A charging roller for charging the electrophotographic photosensitive member; and a brush unit including two brush members that act in contact with the electrophotographic photosensitive member;
3. A process cartridge, wherein the brush unit is supported by the process means support mechanism according to claim 1 or 2. In an electrophotographic image forming apparatus that develops a latent image formed on an electrophotographic photosensitive member that is a rotating body by a developing unit and transfers the latent image to a recording medium.
A brush unit including two brush members that act in contact with the electrophotographic photosensitive member;
An electrophotographic image forming apparatus, wherein the brush unit is supported by the process means support mechanism according to claim 1 .   6. The electrophotographic image forming apparatus according to claim 5, wherein the image forming apparatus collects the developer remaining on the electrophotographic photosensitive member after the image formed on the electrophotographic photosensitive member is transferred to a recording medium by a developing unit. apparatus.

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