JP4264282B2 - Charging device, process cartridge, and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charging device, a process cartridge, and an image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, an image carrier such as a photoconductor is charged using a discharge phenomenon, and discharge products such as ozone and nitrogen oxide are generated by this discharge phenomenon. If ozone stays in the image forming apparatus at a high concentration, the surface of the image carrier is oxidized, causing a decrease in the photosensitivity of the image carrier and a deterioration in charging performance. is there. In addition, the deterioration of members other than the image carrier is promoted by ozone, and there is a problem that the life of the parts is reduced.
[0003]
In order to solve such a problem, a charging roller disposed opposite to the outer peripheral surface of the image carrier is surrounded by a cover, and the generation of discharge products is reduced by supplying low oxygen gas into the cover. An invention has been proposed (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
JP-A-11-305522
[0005]
[Problems to be solved by the invention]
However, in the invention described in Patent Document 1 described above, the outer periphery of the image carrier is formed from the gap between the edge facing the image carrier and the outer peripheral surface of the image carrier in the case surrounding the charging roller. Oxygen adhering to the surface may enter the case as the image carrier rotates, causing discharge products to be generated.
[0006]
In addition, if the space between the edge of the case facing the image carrier and the outer peripheral surface of the image carrier is closed with an elastic body such as rubber or sponge, the entry of oxygen into the case can be suppressed. However, in this case, another problem that the outer peripheral surface of the image carrier is damaged by contact with the elastic body occurs.
[0007]
An object of the present invention is to reduce the generation of discharge products by introducing a low oxygen gas into a casing member surrounding a charging roller, and the outer peripheral surface of the image carrier and the edge of the casing member facing the image carrier. Is to prevent oxygen from entering the casing member from between the two and further reduce the generation of discharge products in the casing member.
[0008]
[Means for Solving the Problems]
  According to a first aspect of the present invention, there is provided a charging device which is disposed at a position facing the outer peripheral surface of the image carrier and is rotatable around an axis parallel to the rotation axis of the image carrier, and the charging roller A casing member that surrounds the image carrier and the casing memberSurface movementAttached to an edge on the upstream side along the direction, and a tip portion facing the image carrier side of the image carrierSurface movementA flexible upstream seal that is curved toward the downstream side in the direction and is slidably contacted with the outer peripheral surface of the image carrier, and an introduction in which low oxygen gas is introduced into the casing member Having a mouth,The low oxygen gas is introduced upstream of the charging roller in the casing member in the moving direction of the surface of the image carrier, and is opposite to the image carrier across the charging roller of the casing member. The surface is shaped along the surface of the opposing charging roller, and the surface of the charging roller that faces the surface of the image carrier is moved in the same direction as the moving direction of the surface of the image carrier. By rotating the charging roller, an air flow accompanying the rotation of the charging roller is generated,
The upstream seal is pressed against the surface of the image carrier by the pressure of the low oxygen gas introduced upstream of the charging roller in the moving direction of the image carrier surface.It is.
[0009]
Here, examples of the “low oxygen gas” include nitrogen gas and rare gas, and gas having a lower oxygen concentration than the atmosphere can also be included. In addition, the lower the oxygen concentration in the low oxygen gas, the better. This is because the lower the oxygen concentration in the low oxygen gas, the smaller the amount of discharge products generated.
[0010]
Accordingly, when the low oxygen gas is introduced into the casing member from the inlet, the oxygen concentration in the casing member is lowered, and the generation of discharge products accompanying the discharge phenomenon is reduced. Furthermore, the pressure in the casing member increases due to the introduction of the low oxygen gas into the casing member, and the upstream seal is pressed against the outer peripheral surface of the image carrier due to the increased pressure, so that it adheres to the outer peripheral surface of the image carrier. Oxygen is prevented from entering the casing member with the rotation of the image carrier, and the generation of discharge products accompanying the discharge phenomenon is further reduced.
[0015]
Claim2The charging device according to the invention described in claim1In this charging apparatus, the charging roller is driven by the image carrier.
  Claim3The charging device according to the invention described in claim1 or 2A partition plate having a double structure in the space between the charging roller and the casing member.The low oxygen gas, which is provided along the longitudinal direction of the casing member and is introduced upstream of the image carrier surface movement direction, again passes from the upstream side of the image carrier surface movement direction in the casing member via the downstream side. By circulating toward the upstream side, the low oxygen gas is diffused over the longitudinal direction in the casing member..
  Claim4The process cartridge according to the present invention includes an image carrier, and3And a developing device that supplies toner to the electrostatic latent image formed on the outer peripheral surface of the image carrier to form a toner image. Removably attached.
[0016]
  Therefore, according to this process cartridge, claims 1 to3As in any one of the inventions described above, the generation of discharge products accompanying the discharge phenomenon is reduced.
[0017]
  Claim5According to the invention described in claim 4, the process cartridge according to claim 4 includes a low oxygen gas supply device connected to the introduction port and configured to supply a low oxygen gas from the introduction port.
[0018]
Therefore, since the low oxygen gas supply device is integrated with the process cartridge, the low oxygen gas supply device can be replaced with the process cartridge, and the handling property is improved.
[0019]
  Claim6The image forming apparatus according to the invention described in claim5The process cartridge described above, an optical writing device that forms an electrostatic latent image on the image carrier provided in the process cartridge, and a toner image formed on the outer peripheral surface of the image carrier are transferred to a recording medium And a fixing device for fixing the toner image transferred to the recording medium.
[0020]
Therefore, according to this image forming apparatus, since the generation of the discharge product during the discharge for charging the image carrier is reduced, the deterioration of the image quality due to the influence of the discharge product is prevented.
[0021]
  Claim7The image forming apparatus according to the invention described in claim4The process cartridge described above, a low oxygen gas supply device connected to the inlet, an optical writing device for forming an electrostatic latent image on the image carrier provided in the process cartridge, and the image carrier A transfer device that transfers the toner image formed on the outer peripheral surface of the recording medium to a recording medium, and a fixing device that fixes the toner image transferred to the recording medium.
[0022]
Therefore, according to this image forming apparatus, since the generation of the discharge product during the discharge for charging the image carrier is reduced, the deterioration of the image quality due to the influence of the discharge product is prevented. Further, since the low oxygen gas supply device is provided in the image forming apparatus separately from the process cartridge, the low oxygen gas supply device can be continuously used without replacing the low oxygen gas supply device when the process cartridge is replaced.
[0023]
  Claim8The described invention is claimed.6Or7The image forming apparatus according to claim 1, further comprising a control unit that starts applying a voltage to the charging roller after a predetermined time has elapsed after the charging roller rotates and the supply of the low oxygen gas from the low oxygen gas supply device is started. .
[0024]
Therefore, when the voltage is applied to the charging roller, the casing member is filled with the low oxygen gas, so that the generation of discharge products during charging of the image carrier is reliably reduced.
[0025]
  Claim9The described invention is claimed.6Or7The low-oxygen gas is supplied from the low-oxygen gas supply device after a predetermined time has elapsed after the charging roller is rotated in a predetermined direction, and the low-oxygen gas supply is started for a predetermined time Control means for starting application of a voltage to the charging roller after elapse of time.
[0026]
Therefore, when the voltage is applied to the charging roller, the casing member is filled with the low oxygen gas, so that the generation of discharge products during charging of the image carrier is reliably reduced. Further, by supplying the low oxygen gas after rotating the charging roller and generating an air flow around the charging roller, the casing member can be quickly put on the air flow generating the low oxygen gas. .
[0027]
DETAILED DESCRIPTION OF THE INVENTION
  The present inventionIs common except for the rotation direction of the charging roller.FirstReference exampleWill be described with reference to FIGS. 1 and 2 show the overall structure of a color printer which is an image forming apparatus. In the apparatus main body 2 of the color printer 1, four process cartridges 3Y, 3C, 3M, and 3K, a conveyance belt 4, a transfer roller 5 that is a transfer device, and a storage unit that stores a recording medium S of recording paper or OHP paper. 6, optical writing devices 7Y, 7C, 7M, 7K, a fixing device 8 and the like are provided. Note that the subscripts Y, C, M, and K in the process cartridges 3Y, 3C, 3M, and 3K and the optical writing devices 7Y, 7C, 7M, and 7K are toner colors (Y is yellow, C is cyan, M stands for magenta, K stands for black), and this suffix is omitted as necessary.
[0028]
The process cartridge 3 forms toner images of different colors, and as shown in FIG. 3, a drum-shaped photosensitive member 9 as an image carrier, and a charging device that uniformly charges the surface of the photosensitive member 9 10. A developing device 11 for supplying toner to an electrostatic latent image formed on the outer peripheral surface of the photoconductor 9 to form a toner image; a residual amount on the outer peripheral surface of the photoconductor 9 after the toner image is transferred to the recording medium S The cleaning device 12 collects the used toner, the low oxygen gas supply device 13 and the like. As shown in FIG. 2, each process cartridge 3 is attached so that it can be taken out of the apparatus main body 2 after the conveyor belt 4 is rotated to the open position.
[0029]
The optical writing device 7 includes a polygon mirror and the like, exposes the outer peripheral surface of the photoconductor 9 according to image information, and forms an electrostatic latent image on the outer peripheral surface of the photoconductor 9.
[0030]
The basic operation of image formation in the color printer 1 having such a configuration will be described. After the photosensitive member 9 in each process cartridge 3 is rotated, the photosensitive member 9 is exposed according to the image information of each color by each optical writing device 7, and an electrostatic latent image is formed on the outer peripheral surface of the photosensitive member 9. Is done. Toner is supplied from the developing device 11 to the electrostatic latent image, and the electrostatic latent image is visualized as a toner image. The recording medium S adsorbed on the conveyance belt 4 is conveyed at the timing and timing of toner image formation, and the toner images on the photoreceptor 9 are successively transferred onto the recording medium S by the action of the transfer roller 5. The recording medium S to which the toner image has been transferred is conveyed to the fixing device 8 and subjected to a fixing process, and the recording medium S after the fixing process is discharged onto a paper discharge tray 14 formed on the upper surface of the apparatus body 2. The
[0031]
Next, details of the process cartridge 3 will be described with reference to FIGS.
[0032]
The photoconductor 9 is a negatively charged organic photoconductor and is rotationally driven in the direction of the arrow (counterclockwise direction) by a rotation drive mechanism (not shown).
[0033]
The charging device 10 includes a charging roller 15 and a casing member 16 surrounding the charging roller 15. The charging roller 15 is a flexible roller in which a medium-resistance foamed urethane layer 15b in which a urethane resin, carbon black as conductive particles, a sulfurizing agent, a foaming agent, and the like are formed on a core metal 15a is formed in a roller shape. The photoconductor 9 is disposed in a non-contact manner on the outer peripheral surface of the photoconductor 9 and is driven to rotate in the counter direction with respect to the photoconductor 9. The material of the middle resistance layer formed on the metal core 15a in the charging roller 15 is not limited to the above, but urethane, ethylene, propylene, diene polyethylene (EPDM), butadiene acrylonitrile rubber (NBR), silicone rubber In addition, a rubber material in which a conductive material such as carbon black or a metal oxide is dispersed to adjust resistance in isoprene rubber or the like, or a foamed material thereof can be used.
[0034]
A DC voltage of −400 V and an AC voltage of amplitude 900 V / frequency 1 kHz are applied to the metal core 15 a of the charging roller 15 from a charging bias application power source, and a discharge phenomenon occurs between the charging roller 15 and the photoconductor 9, thereby causing photosensitivity. The outer peripheral surface of the body 9 is charged to about −400V.
[0035]
  Note that the voltage applied to the cored bar 15a of the charging roller 15 may be only a DC voltage. When the voltage applied to the metal core 15a of the charging roller 15 is only a DC voltage, a discharge phenomenon that occurs between the photosensitive member 9 and the charging roller 15 in order to charge the photosensitive member 9 occurs.Surface movementThis occurs mainly on the upstream side of the closest approach position with the charging roller 15 along the direction. The reason is that the discharge is performed on the upstream side, so that the potential difference between the photoconductor 9 and the charging roller 15 is reduced on the downstream side, and the discharge phenomenon does not occur.
[0036]
In the developing device 11, toner particles (not shown) are stored. Further, in the developing device 11, a developing roller 11a that rotates clockwise to come into contact with the photosensitive member 9, a supply roller 11b that coats the developing roller 11a with toner particles, and a toner that is coated on the developing roller 11a An elastic blade 11c that negatively charges toner particles by friction while regulating the thickness of the particles, and a stirring member 11d that moves the toner particles in the developing device 11 toward the supply roller 11b while stirring.
[0037]
  The cleaning device 12Surface movementIt has a cleaning blade 12a that abuts against the direction with a counter and a waste toner box 12b that stores the cleaned toner particles as waste toner.
[0038]
The low oxygen gas supply device 13 is a device that supplies low oxygen gas such as nitrogen gas or rare gas into the casing member 16, and is supplied with a low oxygen gas storage unit 13a for storing low oxygen gas. A supply pipe 13b is provided. Note that a shutter 17 that is driven to open and close is provided at a connection point between the low oxygen gas storage portion 13a and the supply pipe 13b.
[0039]
Here, a toner image forming operation in the process cartridge 3 will be described below. Image processing is performed on image information in a format such as a page description language or a bitmap transferred from a computer or the like, and is output from the optical writing device 7 to write data for exposing the outer peripheral surface of the photosensitive member 9. Converted.
[0040]
Prior to exposure from the optical writing device 7, the photosensitive member 9 starts rotating in the direction of the arrow in FIG. 3 so that the moving speed of the outer peripheral surface becomes a predetermined speed. The charging roller 15 is driven to rotate in the counter direction with respect to the photosensitive member 9. At this time, a DC voltage of −400 V and an AC voltage of amplitude 900 V / frequency 1 kHz are applied from the charging bias application power source to the metal core 15 a of the charging roller 15, and a discharge phenomenon occurs between the charging roller 15 and the photoconductor 9. As a result, the outer peripheral surface of the photosensitive member 9 is charged to about −400V.
[0041]
The optical writing device 7 (7Y, 7C, 7M, 7K) performs exposure according to the writing data on the charged photoreceptor 9. That is, by changing the potential of the image portion by light irradiation, a difference from the potential of the non-image portion not irradiated with light is generated, and an electrostatic latent image is formed by this potential contrast.
[0042]
The electrostatic latent image formed on the photoconductor 9 by the optical writing device 7 is developed by the developing device 11, and this developing device 11 forms a toner image on the photoconductor 9 by a contact type non-magnetic one-component developing system. To do. Specifically, the developing roller 11a is rotated in the clockwise direction, and the supply roller 11b made of an elastic body rotating in the clockwise direction is brought into contact with the developing roller 11a, whereby the toner particles on the supplying roller 11b are moved onto the developing roller 11a. To coat. The toner particles coated on the developing roller 11a are negatively charged by friction with the elastic blade 11c while the thickness thereof is regulated by the elastic blade 11c, and then conveyed to a portion facing the photoreceptor 9 as the developing roller 11a rotates.
[0043]
In a portion where the developing roller 11a and the photosensitive member 9 are opposed to each other, a DC bias voltage of −300 V is applied to the developing roller 11a, so that a DC electric field is formed between the developing roller 11a and the photosensitive member 9, and negative charging is performed. The toner particles thus adhered selectively adhere only to the image portion on the photoconductor 9 by the direct current electric field to form a toner image.
[0044]
The recording medium S is transported by the transport belt 4 in accordance with the timing at which the toner image formed on the photoconductor 9 reaches the transfer area, which is the opposite portion between the transfer roller 5 and the photoconductor 9, and the toner on the photoconductor 9. The image is transferred to the recording medium S by the voltage applied to the transfer roller 5.
[0045]
On the other hand, the toner (transfer residual toner) remaining on the photosensitive member 9 without being transferred is cleaned by the cleaning device 12, and the outer peripheral surface of the cleaned photosensitive member 9 is charged by the charging device 10 for the next image formation. The
[0046]
  Next, the structure relating to the supply of low oxygen gas, which is a feature of the present invention, will be described. As shown in FIG. 5, the charging device 10 includes a charging roller 15 and a casing member 16 surrounding the charging roller 15. The casing member 16 is formed in an elongated shape along the axial direction of the charging roller 15, and the edge of the casing member 16 that faces the outer peripheral surface of the photoconductor 9 and the outer peripheral surface of the photoconductor 9 are not in contact with each other. Opposite to. Of the photosensitive member 9 in the casing member 16.Surface movementA flexible upstream seal 18 is attached to the upstream edge along the direction. The upstream seal 18 is formed in a long shape extending along the axial direction of the charging roller 15, one end in a direction perpendicular to the long direction is fixed to the edge of the casing member 16, and the other end is The free end extends toward the photoreceptor 9 side. The length dimension from the edge of the casing member 16 to the free end side tip of the upstream seal 18 is set to be larger than the distance between the edge of the casing member 16 and the outer peripheral surface of the photoreceptor 9. The free end side of the side seal 18 isSurface movementIt curves toward the downstream side in the direction and is in sliding contact with the outer peripheral surface of the photoreceptor 9.
[0047]
An introduction port 19 is formed on one side surface of the casing member 16 in the direction along the axis of the charging roller 15 and in the vicinity of the upstream seal 18. The introduction port 19 is a portion where the low oxygen gas is introduced into the casing member 16 from the low oxygen gas supply device 13, and the tip of the supply pipe 13b is connected thereto.
[0048]
At the time of image formation, the photosensitive member 9 rotates in the arrow direction (counterclockwise direction) and the charging roller 15 rotates in the counter direction. As the charging roller 15 rotates, an airflow A in the follower direction along the rotation direction of the charging roller 15 is generated inside the casing member 16 and on the outer periphery of the charging roller 15 as indicated by a broken line. Yes.
[0049]
When low oxygen gas is introduced into the casing member 16 from the inlet 19 in such a state, the low oxygen gas introduced into the casing member 16 passes through the casing member 16 in the axial direction of the charging roller 15. And a part of the low oxygen gas flows into the discharge region a on the upstream side between the charging roller 15 and the photoconductor 9, which is a region where the gas is carried out by the airflow A and becomes a low pressure state. Get in. The low oxygen gas that has entered the discharge region a rides on the airflow A and flows along the outer peripheral surface of the charging roller 15, enters the discharge region b on the downstream side between the charging roller 15 and the outer peripheral surface of the photoreceptor 9, Thereafter, the air is exhausted out of the casing member 16 through a gap between the edge of the casing member 16 and the outer peripheral surface of the photosensitive member 9. Thereby, the inside of the casing member 16 is filled with the low oxygen gas. The introduction of the low oxygen gas from the introduction port 19 is continuously performed during the image forming operation. Further, when the low oxygen gas is introduced into the casing member 16, the pressure in the casing member 16, particularly, the pressure in the vicinity of the introduction port 19 is increased, and the upstream seal 18 is moved to the outer periphery of the photoreceptor 9 by this pressure increase. Pressed against the surface.
[0050]
Here, the inside of the casing member 16 is filled with the low oxygen gas, and the low oxygen gas enters the discharge region a on the upstream side and the discharge region b on the downstream side in the casing member 16, so that these discharge regions a, b The generation of discharge products due to the discharge phenomenon between the charging roller 15 and the photoconductor 9 is reduced or prevented.
[0051]
Furthermore, since the upstream side seal 18 is pressed against the outer peripheral surface of the photoconductor 9 by the pressure increase in the casing member 16 due to the low oxygen gas introduced into the casing member 16, oxygen adhering to the outer peripheral surface of the photoconductor 9 is photosensitive. It is possible to prevent the upstream seal 18 from entering the casing member 16 as the body 9 rotates, and the generation of discharge products due to the discharge phenomenon is further reduced or prevented.
[0052]
FIG. 6 is a block diagram showing the electrical connection of the portion related to the supply of the low oxygen gas in the color printer 1. The color printer 1 is provided with a control unit 20 having a microcomputer configuration including a CPU, a ROM, a RAM (all not shown), and the like. Are connected to a drive motor 21 that rotates the motor, a voltage application switch 22 that applies a voltage to the charging roller 15, an actuator 23 that drives the shutter 17, a timer 24, a start key 25 that starts an image forming operation, and the like. The ROM of the control unit 20 stores various control programs such as a control program for supplying a low oxygen gas when the start key 25 is pressed and a control program for performing an image forming operation. Has been.
[0053]
When supplying the low oxygen gas, first, it is determined whether or not the start key 25 is depressed (step S1). If the start key 25 is depressed, the drive motor 21 is driven (step S2). It is determined whether or not a predetermined time has elapsed after the drive motor 21 is driven (step S3). After a predetermined time has elapsed, the actuator 23 is driven and the shutter 17 is opened (step S4). The predetermined time determined in step S <b> 3 is a time required for an air flow to be generated around the charging roller 15 by the rotation of the charging roller 15, for example, a time required for the charging roller 15 to rotate 10 times.
[0054]
After the shutter 17 is opened in step S4, it is determined whether or not a predetermined time has elapsed (step S5), and the voltage application switch 22 is turned on after the predetermined time has elapsed (step S6). The predetermined time determined in step S5 is that the low oxygen gas supplied from the introduction port 19 through the supply pipe 13b from the low oxygen gas storage portion 13a into the casing member 16 when the shutter 17 is opened. This is the time required for charging, for example, the time required for the charging roller 15 to rotate five times. When the voltage application switch 22 is turned on in step S6, a voltage is applied to the charging roller 15, and a discharge phenomenon occurs between the photosensitive member 9 and the charging roller 15 with the application of the voltage. Charged. At the time of this charging, since the discharge areas a and b are filled with the low oxygen gas, the generation of discharge products is reduced or prevented. Here, the charging roller 15, which is one of the functions of the control unit 20, rotates in a predetermined direction and the supply of the low oxygen gas from the low oxygen gas supply device 13 is started by the above-described processing from step S <b> 2 to step S <b> 6. Control means for starting voltage application to the charging roller 15 after a predetermined time later, or supply of low oxygen gas from the low oxygen gas supply device 13 after a predetermined time after rotating the charging roller 15 in a predetermined direction. The control means is executed to start the voltage application to the charging roller 15 after a predetermined time has elapsed after the supply of the low oxygen gas is started.
[0055]
First2Reference exampleWill be described with reference to FIG. The same parts as those described in FIGS. 1 to 7 are denoted by the same reference numerals, and description thereof is also omitted (the following description is omitted).Reference Example or ImplementationIs the same in the form).
[0056]
  BookReference exampleThe basic structure of the charging device 31 of the first isReference exampleThe charging device 10 is the same as that of the charging device 10, and the introduction of the low oxygen gas is introduced into the surface of the casing member 16 where the upstream side seal 18 is attached and substantially in the center along the axial direction of the charging roller 15. A mouth 32 is formed. The leading end of the supply pipe 13b is connected to the introduction port 32.
[0057]
The low oxygen gas introduced into the casing member 16 from the inlet 32 is filled in the casing member 16 and enters the discharge region a on the upstream side and the discharge region b on the downstream side to charge the photoreceptor 9. The generation of discharge products due to the discharge phenomenon between the charging roller 15 and the photoconductor 9 is reduced or prevented. Furthermore, since the upstream side seal 18 is pressed against the outer peripheral surface of the photoconductor 9 by the pressure increase in the casing member 16 due to the low oxygen gas introduced into the casing member 16, oxygen adhering to the outer peripheral surface of the photoconductor 9 is photosensitive. It is possible to prevent the upstream seal 18 from entering the casing member 16 as the body 9 rotates, and the generation of discharge products accompanying the discharge phenomenon for charging the photoreceptor 9 is further reduced, or To be prevented.
[0058]
  The third of the present inventionReference exampleWill be described with reference to FIG.This reference exampleThe charging device 41 of the firstReference exampleA downstream seal 42 having flexibility is added to the charging device 10.
[0059]
  The downstream side seal 42 is formed on the photosensitive member 9 in the casing member 16.Surface movementIt is attached to an edge portion on the downstream side along the direction, and is formed in a long shape extending along the axial direction of the charging roller 15. One end in a direction orthogonal to the longitudinal direction is fixed to the edge of the casing member 16 and the other end is a free end extending to the photosensitive member 9 side. The length of the downstream seal 42 from the edge of the casing member 16 to the free end side tip is set to be larger than the distance between the edge of the casing member 16 and the outer peripheral surface of the photoreceptor 9. The free end side of the side seal 42Surface movementIt curves toward the downstream side in the direction and is in sliding contact with the outer peripheral surface of the photoreceptor 9.
[0060]
By introducing the low oxygen gas into the casing member 62 from the inlet 19, the low oxygen gas is filled in the casing member 16, and the generation of discharge products due to the discharge phenomenon in the discharge regions a and b is reduced. Or prevented.
[0061]
  Further, the casing member 16 is formed of the photoconductor 9.Surface movementSince the upstream side and the downstream side along the direction are closed by the upstream side seal 18 and the downstream side seal 42, the pressure in the casing member 16 when the low oxygen gas is introduced into the casing member 16 is changed to the first pressure.Reference exampleIt can be higher than the case. As a result, the pressing force of the upstream seal 18 against the outer peripheral surface of the photoconductor 9 is increased, and oxygen attached to the outer peripheral surface of the photoconductor 9 may enter the casing member 16 as the photoconductor 9 rotates. This is further prevented, and the generation of discharge products accompanying the discharge phenomenon for charging the photosensitive member 9 is further reduced or prevented.
[0062]
  Furthermore, by providing this downstream side seal 42, the photosensitive member 9 in the casing member 16 is protected.Surface movementIt is possible to prevent oxygen from entering the casing member 16 from the downstream side.
[0063]
When the pressure in the casing member 16 rises to a predetermined value due to the introduction of the low oxygen gas into the casing member 16, the downstream seal 42 is partially lifted away from the outer peripheral surface of the photoreceptor 9. As a result, the exhaust is performed, and the pressure in the casing member 16 is automatically adjusted.
[0064]
  First of the present invention1The embodiment will be described with reference to FIG. In the charging device 51 of the present embodiment, the charging roller 15 is rotated by the photosensitive member 9. For this reason, a gear mechanism or the like for transmitting the rotational force to the charging roller 15 becomes unnecessary, and the structure is simplified. Of the photosensitive member 9 in the casing member 16.Surface movementAn upstream seal 18 is attached to an upstream edge along the direction, and an introduction port 19 is formed on one side surface of the casing member 16 and in the vicinity of the upstream seal 18.
[0065]
  Further, a DC voltage is used as a voltage applied to the charging roller 15 in order to charge the photosensitive member 9. For this reason, the discharge phenomenon between the photoconductor 9 and the charging roller 15 is caused bySurface movementIt occurs mainly in the upstream discharge region a along the direction. The reason is that discharge is performed in the discharge region a on the upstream side, so that the photoconductor 9 and the charging roller 15 face each other.Surface movementThis is because, on the downstream side in the direction, the potential difference between the photoconductor 9 and the charging roller 15 becomes small, and the discharge phenomenon does not occur.
[0066]
In such a configuration, the rotation of the charging roller 15 generates a rotating airflow A ′ around the charging roller 15, and oxygen flows into the casing member 16 on the downstream side of the casing member 16 from the airflow A ′. Is introduced. However, since this downstream region in the casing member 16 is a region where no discharge phenomenon occurs, no discharge product is generated even if oxygen is introduced into this region.
[0067]
On the other hand, the introduction of the low oxygen gas from the introduction port 19 fills the upstream discharge region a with the low oxygen gas. Further, the upstream seal 18 is pressed against the outer peripheral surface of the photoconductor 9 due to the pressure increase due to the introduced low oxygen gas, thereby preventing external oxygen from entering the discharge region a as the photoconductor 9 rotates. The Further, the introduction of the low oxygen gas prevents oxygen on the airflow A ′ from entering the discharge region a. As described above, the generation of discharge products in the discharge region a is reduced or prevented.
[0068]
  First of the present invention2The embodiment will be described with reference to FIG. In the charging device 61 of the present embodiment, the charging roller 15 is rotated by the photosensitive member 9. For this reason, a gear mechanism for transmitting the rotational force to the charging roller 15 is unnecessary, and the structure is simplified. The casing member 62 surrounding the charging roller 15 has a double structure partitioned by a partition plate 63. The outer peripheral side space 64 a and the inner peripheral side space 64 b partitioned by the partition plate 63 are the same as those of the photoreceptor 9 in the casing member 51.Surface movementThe upstream side and the downstream side along the direction communicate with each other.
[0069]
  The photosensitive member 9 in the casing member 62Surface movementAn upstream seal 18 is attached to the upstream edge along the direction, and the photosensitive member 9 in the casing member 62 is fixed.Surface movementA downstream seal 42 is attached to the downstream edge along the direction.
[0070]
The surface of the casing member 62 to which the upstream side seal 18 is attached and in the substantially central portion along the axial direction of the charging roller 15 is an introduction port through which low oxygen gas is introduced in communication with the outer circumferential side space 64a. 65 is formed. The leading end of the supply pipe 13b is connected to the introduction port 65.
[0071]
In such a configuration, the rotation of the charging roller 15 generates an airflow A ′ in the following direction in the inner circumferential space 64 b around the charging roller 15, and this airflow A ′ is upstream of the casing member 62. It enters into the outer peripheral side space 64a at the end, and flows in the outer peripheral side space 64a as an air flow B in the opposite direction. The airflow B flowing in the outer peripheral space 64a enters the inner peripheral space 64b at the downstream end in the casing member 62 and flows in the direction of rotation by the charging roller 15 as an airflow A ′.
[0072]
  When the low oxygen gas is introduced from the introduction port 65 into the outer circumferential side space 64 a where such an air flow B is generated, the introduced low oxygen gas diffuses in the longitudinal direction along the axial direction of the charging roller 15. While flowing on the air flow B, reaching the downstream discharge region b, and then riding on the air flow A ′ and flowing in the inner circumferential space 64b to discharge the upstream discharge region.aTo enter the outer peripheral space 64a again.
[0073]
Thereby, the low oxygen gas is filled in the casing member 62, and generation | occurrence | production of the discharge product accompanying the discharge phenomenon in the discharge area | region a and b is reduced or prevented. Further, when the low oxygen gas is introduced into the casing member 62 and the pressure in the casing member 62 is increased, the upstream seal 18 is pressed against the outer peripheral surface of the photoconductor 9, and oxygen attached to the outer peripheral surface of the photoconductor 9. Is prevented from entering the casing member 16 as the photosensitive member 9 rotates, and the generation of discharge products due to the discharge phenomenon is further reduced or prevented.
[0074]
When the low oxygen gas is introduced into the casing member 62 and the pressure in the casing member 62 rises to a predetermined value, the downstream seal 42 is partially lifted away from the outer peripheral surface of the photoreceptor 9. Thus, the exhaust is performed, and the pressure in the casing member 62 is automatically adjusted.
[0075]
  First of the present invention3The embodiment will be described with reference to FIG. The process cartridge 71 according to the present embodiment includes the photosensitive member 9, the charging device 10, the developing device 11, and the cleaning device 12. However, the process cartridge 71 includes the process cartridge 3 according to each embodiment described above in that it does not include the low oxygen gas supply device. The structure is different.
[0076]
In a printer 72 which is an image forming apparatus using the process cartridge 71 of the present embodiment, a low oxygen gas supply device 73 is provided on the apparatus main body 74 side of the printer 72. The low oxygen gas supply device 73 includes a low oxygen gas storage portion 73 a for storing low oxygen gas and a supply pipe 73 b for supplying low oxygen gas, and is provided in a process cartridge 71 mounted in the apparatus main body 74. The charging device 10 is detachably connected to the introduction port 19.
[0077]
According to the present embodiment, it is not necessary to replace the low oxygen gas supply device 73 integrally when replacing the process cartridge 71, and the low oxygen gas supply device 73 can be replaced separately from the process cartridge 71 as necessary. Yes. Thereby, it is not necessary to match the lifetimes of the process cartridge 71 and the low oxygen gas supply device 73, the degree of freedom in designing the process cartridge 71 and the low oxygen gas supply device 73 is increased, and the cost can be reduced. .
[0078]
【The invention's effect】
According to the charging device of the first aspect of the present invention, when the low oxygen gas is introduced into the casing member from the introduction port, the oxygen concentration in the casing member becomes low, and the generation of discharge products accompanying the discharge phenomenon occurs. Further, the pressure in the casing member is increased by the introduction of the low oxygen gas into the casing member, and the upstream seal is pressed against the outer peripheral surface of the image carrier by the increase in pressure. It is possible to prevent oxygen adhering to the outer peripheral surface from entering the casing member as the image carrier rotates, and to further reduce the generation of discharge products accompanying the discharge phenomenon.
[0081]
  Claim4According to the process cartridge of the invention described in claims 1 to3Therefore, it is possible to reduce the generation of discharge products accompanying the discharge phenomenon.
[0082]
  Claim5According to the described invention, the claims4In the described process cartridge, since it has a low oxygen gas supply device that is connected to the introduction port and supplies low oxygen gas from the introduction port, the low oxygen gas supply device can be exchanged with the process cartridge, etc. Handleability can be improved.
[0083]
  Claim6According to the image forming apparatus of the invention described in the claims,5Since the process cartridge described above is included, the generation of discharge products during discharge for charging the image carrier can be reduced, and deterioration in image quality due to the influence of the discharge products can be prevented.
[0084]
  Claim7According to the image forming apparatus of the invention described in the claims,4Since the process cartridge described above and the low oxygen gas supply device connected to the introduction port are provided, the generation of discharge products during discharge for charging the image carrier is reduced, and the image due to the influence of the discharge products Reduced quality can be prevented, and since the low oxygen gas supply device is provided in the image forming apparatus separately from the process cartridge, the low oxygen gas supply device can be continuously replaced without replacing the process cartridge. Can be used.
[0085]
  Claim8According to the described invention, the claims6Or7The image forming apparatus according to claim 1, further comprising a control unit that starts applying a voltage to the charging roller after a predetermined time has elapsed after the charging roller rotates and the supply of the low oxygen gas from the low oxygen gas supply device is started. Therefore, when the voltage is applied to the charging roller, the inside of the casing member is filled with the low oxygen gas, so that the generation of discharge products during charging of the image carrier can be reliably reduced.
[0086]
  Claim9According to the described invention, the claims6Or7The low-oxygen gas is supplied from the low-oxygen gas supply device after a predetermined time has elapsed after the charging roller is rotated in a predetermined direction, and the low-oxygen gas supply is started for a predetermined time Since it has a control means for starting the voltage application to the charging roller after elapse of time, the casing member is filled with low oxygen gas when the voltage is applied to the charging roller. The generation can be reliably reduced, and the low oxygen gas is supplied to the casing member by supplying the low oxygen gas after rotating the charging roller and generating an air flow around the charging roller. It can be carried out promptly by putting it on the flowing air current.
[Brief description of the drawings]
FIG. 1 shows the first of the present invention.Reference exampleIt is the schematic which shows the color printer.
FIG. 2 is a schematic view showing a process cartridge attached / detached state.
FIG. 3 is an enlarged sectional view showing a process cartridge.
FIG. 4 is an enlarged plan view showing a process cartridge.
FIG. 5 is a cross-sectional view showing the charging device further enlarged.
FIG. 6 is a block diagram showing an electrical connection of a portion related to supply of low oxygen gas in the printer.
FIG. 7 is a flowchart illustrating supply of low oxygen gas.
FIG. 8 shows the second of the present invention.Reference exampleIt is sectional drawing which shows this charging device.
FIG. 9 shows a third embodiment of the present invention.Reference exampleIt is sectional drawing which shows this charging device.
FIG. 10 shows the first of the present invention.1It is sectional drawing which shows the charging device of embodiment.
FIG. 11 shows the first of the present invention.2It is sectional drawing which shows the charging device of embodiment.
FIG. 12 shows the first of the present invention.3It is a top view which shows the printer of embodiment.

Claims (9)

A charging roller disposed at a position facing the outer peripheral surface of the image carrier, and rotatable around an axis parallel to the rotation axis of the image carrier;
A casing member surrounding the charging roller;
The casing member is attached to an upstream edge of the image carrier along the surface movement direction of the image carrier, and a tip portion directed toward the image carrier is curved toward the surface movement direction downstream of the image carrier. A flexible upstream seal that is in sliding contact with the outer peripheral surface of the image carrier;
Formed in the casing member, and having an introduction port into which low oxygen gas is introduced into the casing member,
The low oxygen gas is introduced upstream of the charging roller in the casing member in the moving direction of the image carrier surface,
The surface of the casing member opposite to the image carrier with the charging roller interposed therebetween is shaped along the surface of the opposing charging roller, and faces the surface of the image carrier of the charging roller. When the charging roller rotates so that the surface to be moved moves in the same direction as the moving direction of the surface of the image carrier, an air flow is generated as the charging roller rotates,
The charging device according to claim 1, wherein the upstream seal is pressed against the surface of the image carrier by the pressure of the low oxygen gas introduced upstream of the charging roller in the moving direction of the image carrier surface . The charging device according to claim 1 , wherein the charging roller is configured to be carried by the image carrier. A partition plate having a double structure in the space between the charging roller and the casing member is provided along the longitudinal direction of the casing member, and the low oxygen gas introduced upstream in the moving direction of the image carrier surface The low oxygen gas is diffused in the longitudinal direction in the casing member by circulating from the upstream side in the moving direction of the image carrier surface in the casing member to the upstream side through the downstream side again. The charging device according to claim 1 or 2 . An image carrier, a charging device according to any one of claims 1 to 3 , and a developing device that forms a toner image by supplying toner to an electrostatic latent image formed on an outer peripheral surface of the image carrier; And a process cartridge that is detachably attached to the image forming apparatus. The process cartridge according to claim 4 , further comprising a low oxygen gas supply device connected to the introduction port and configured to supply a low oxygen gas from the introduction port. 6. A process cartridge according to claim 5, an optical writing device for forming an electrostatic latent image on the image carrier provided in the process cartridge, and a toner image formed on an outer peripheral surface of the image carrier. An image forming apparatus comprising: a transfer device that transfers to a medium; and a fixing device that fixes a toner image transferred to the recording medium. 5. The process cartridge according to claim 4 , a low oxygen gas supply device connected to the inlet, an optical writing device that forms an electrostatic latent image on the image carrier provided in the process cartridge, and An image forming apparatus comprising: a transfer device that transfers a toner image formed on an outer peripheral surface of an image carrier to a recording medium; and a fixing device that fixes the toner image transferred to the recording medium. The charging roller according to claim 6 or 7, wherein a control unit operable to start voltage application to the charging roller from hypoxic gas delivery system after a predetermined time elapses after the supply of the low oxygen gas is started with the rotating Image forming apparatus. A low oxygen gas is supplied from the low oxygen gas supply device after a lapse of a predetermined time after rotating the charging roller, and a voltage is applied to the charging roller after a lapse of a predetermined time after the supply of the low oxygen gas is started. the image forming apparatus according to claim 6 or 7, wherein a control means for starting.

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