JP4264281B2 - 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, when a low oxygen gas is supplied into the case surrounding the charging roller, ventilation is low in the discharge region between the image carrier and the charging roller. The discharge region is not easily filled with the low oxygen gas, and the effect of reducing the generation of discharge products by supplying the low oxygen gas cannot be sufficiently obtained.
[0006]
The object of the present invention is to improve the ventilation of the discharge area between the image carrier and the charging roller when the low oxygen gas is supplied into the casing member surrounding the charging roller, and the low oxygen gas enters the discharge area. Is to reduce the generation of discharge products accompanying the discharge phenomenon.
[0007]
[Means for Solving the Problems]
  Claim 1 to9Of the described inventionProcess cartridgeIsAn image carrier;A charging roller that is disposed at a position facing the outer peripheral surface of the image carrier and rotates in a follower direction or counter direction with respect to the image carrier, a casing member that surrounds the charging roller, and a rotation direction of the image carrier In addition, it is located between the edge of the casing member and the outer peripheral surface of the image carrier and is positioned on either the upstream side or the downstream side of the charging roller, and low oxygen gas is introduced into the casing member. And the edge of the casing member positioned on the upstream side or downstream side of the charging roller along the rotation direction of the image carrier and opposite to the side on which the introduction port is formed. An exhaust port that is formed between the outer peripheral surface of the image carrier and exhausts the low oxygen gas introduced into the casing member.A charging device; a developing device that supplies toner to an electrostatic latent image formed on the outer peripheral surface of the image carrier to form a toner image; and a low oxygen gas supply device that supplies low oxygen gas from the inlet It has the basic composition of having.
[0008]
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.
[0009]
  Therefore, when the low oxygen gas is introduced into the casing member from the inlet, the low oxygen gas flows in the casing member along the air flow generated around the charging roller as the charging roller rotates, and from the exhaust port. It is exhausted outside the casing member. As a result, ventilation to the low oxygen gas is enhanced throughout the casing member, and the discharge region between the charging roller and the image carrier in the casing member is easily filled with the low oxygen gas, resulting in a discharge phenomenon. The generation of discharge products is reduced.
  In addition, the low oxygen gas supply device can be exchanged with the process cartridge and the handling is improved.
[0010]
  The invention according to claim 1 has the above basic configuration.Process cartridgeThe charging roller rotates in a counter direction with respect to the image carrier, the introduction port is formed on the upstream side of the charging roller along the rotation direction of the image carrier, and the exhaust port is formed on the image carrier. It is formed on the downstream side of the charging roller along the rotation direction.
[0011]
Therefore, the low oxygen gas introduced into the casing member from the upstream inlet port enters the upstream discharge region where the image carrier and the charging roller face each other on the inlet port side, and thereafter, as the charging roller rotates. Then, it rides on the airflow generated around the charging roller and flows inside the casing member toward the exhaust port side, enters the discharge region on the downstream side where the image carrier and the charging roller face each other, and then is exhausted from the exhaust port. . For this reason, the low oxygen gas enters the discharge area on the upstream side and the downstream side between the charging roller and the image carrier and the ventilation property to the low oxygen gas in the discharge area becomes high, and the discharge accompanying the discharge phenomenon. Product generation is reduced. Further, the introduction of the low oxygen gas into the casing member from the introduction port is favorably performed on the airflow generated around the image carrier as the image carrier is rotated.
[0012]
  The invention according to claim 2 has the above basic configuration.Process cartridgeThe charging roller rotates in a rotating direction with respect to the image carrier, the introduction port is formed downstream of the charging roller along the rotation direction of the image carrier, and the exhaust port is the image carrier. Is formed on the upstream side of the charging roller along the rotational direction of the.
[0013]
Therefore, the low oxygen gas introduced into the casing member from the downstream inlet port enters the downstream discharge area where the image carrier and the charging roller face each other on the inlet port side, and then the charging roller rotates. Then, the air travels around the charging roller and flows through the casing member toward the exhaust port, enters the discharge region on the upstream side where the image carrier and the charging roller face each other, and is then exhausted from the exhaust port. For this reason, the low oxygen gas enters the discharge area on the downstream side and the upstream side between the charging roller and the image carrier, and the ventilation property to the low oxygen gas in the discharge area becomes high, and the discharge accompanying the discharge phenomenon. Product generation is reduced.
[0014]
  According to a fourth aspect of the present invention, in the charging device according to the first aspect, the voltage applied to the charging roller is a DC voltage.The
[0015]
Here, by setting the voltage applied to the charging roller to a direct current voltage, the discharge between the charging roller and the image carrier is mainly caused by the image carrier more than the closest position between the image carrier and the charging roller. It occurs upstream along the direction of rotation.
[0016]
Therefore, when the low oxygen gas is introduced into the casing member from the upstream inlet along the rotation direction of the image carrier, the discharge region located on the upstream side between the charging roller and the image carrier is reduced. It becomes easy to be filled with oxygen gas, and the generation of discharge products accompanying the discharge phenomenon is reduced.
[0021]
  Claim5The described invention is claimed.1In the process cartridge described above, an outlet from which the low oxygen gas blows out from the low oxygen gas supply device is positioned on the inlet side formed on the upstream side of the charging roller along the rotation direction of the image carrier, The blowing direction of the low oxygen gas from the blowout port is directed to the outer peripheral surface of the image carrier.
[0022]
Therefore, the low oxygen gas blown out from the outlet of the low oxygen gas supply device is introduced into the casing member from the inlet located upstream in the rotation direction of the image carrier, and the low oxygen gas is accompanied by the rotation of the charging roller. It rides on the air current generated around the charging roller and flows through the casing member, and is exhausted from the exhaust port to the outside of the casing member. The introduction of the low oxygen gas reduces the generation of discharge products accompanying the discharge phenomenon. Since the blowing direction of the low oxygen gas blown out from the outlet is directed to the outer peripheral surface of the image carrier, it adheres to the outer peripheral surface of the image carrier and is carried to the discharge region facing the charging roller as the image carrier rotates. Oxygen to be blown off is peeled off from the outer peripheral surface of the image carrier by the low oxygen gas blown out from the blower outlet, so that the entry of oxygen into the casing member is reduced, and the generation of discharge products accompanying the discharge phenomenon is further reduced.
[0023]
  Claim6The described invention is claimed.2In the process cartridge described above, an outlet from which the low oxygen gas blows out from the low oxygen gas supply device is positioned on the inlet side formed on the downstream side of the charging roller along the rotation direction of the image carrier, The direction in which the low oxygen gas is blown out from the outlet is directed upstream in the rotational direction of the image carrier along the outer peripheral surface of the image carrier.
[0024]
Therefore, the low oxygen gas blown out from the outlet of the low oxygen gas supply device is introduced into the casing member from the introduction port located on the downstream side in the rotation direction of the image carrier and is located on the upstream side in the rotation direction of the image carrier. Exhaust from the exhaust port, and the introduction of this low oxygen gas reduces the generation of discharge products accompanying the discharge phenomenon. Since the blowing direction of the low oxygen gas blown out from the blowout port is directed to the upstream side in the rotation direction of the image carrier along the outer peripheral surface of the image carrier, the casing member extends from the inlet located on the downstream side in the rotation direction of the image carrier. Good introduction of low oxygen gas into the inside.
[0025]
  Claim7The image forming apparatus according to the invention described in claim1Or6A process cartridge according to any one of the above, 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 the outer peripheral surface of the image carrier. A transfer device that transfers the image to the recording medium; and a fixing device that fixes the toner image transferred to the recording medium.
[0026]
Therefore, according to this image forming apparatus, since the generation of discharge products during the discharge for charging the image carrier is reduced, the deterioration of the image quality due to the influence of the discharge products is prevented.
[0031]
  Claim8The described invention is claimed.7The image forming apparatus according to claim 1, wherein the charging roller rotates in a predetermined direction and starts applying a voltage to the charging roller after a predetermined time has elapsed after the supply of the low oxygen gas from the low oxygen gas supply device is started. Have means.
[0032]
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.
[0033]
  Claim9The invention described is claimedItem 7The 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.
[0034]
  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. In addition, by supplying the low oxygen gas after rotating the charging roller and generating an air flow around the charging roller, the charging can be quickly carried on the air flow that is filling the casing member of the low oxygen gas. .
According to a third aspect of the present invention, in the charging device according to the first or second aspect, the side opposite to the opening side in the longitudinal direction of the casing member is curved along the outer peripheral surface of the charging roller.
According to a ninth aspect of the present invention, there is provided a charging roller that is disposed at a position facing the outer peripheral surface of the image carrier and rotates in a rotating direction with respect to the moving direction of the image carrier surface at the facing position; A casing member that surrounds the roller, and is formed between an edge of the casing member and an outer peripheral surface of the image carrier located on the upstream side of the charging roller along the rotation direction of the image carrier, An introduction port into which low oxygen gas is introduced into the member, and the casing located on the downstream side of the charging roller along the rotation direction of the image carrier and opposite to the side on which the introduction port is formed. A charging device formed between an edge of the member and an outer peripheral surface of the image carrier, and having an exhaust port through which the low oxygen gas introduced into the casing member is exhausted; and an outer periphery of the image carrier On the electrostatic latent image formed on the surface. And a developing device that forms a toner image by supplying a toner, and a low-oxygen gas supply device that supplies low-oxygen gas from the introduction port is provided in a process cartridge that is detachably attached to the image forming device The blowout direction of the low oxygen gas from the outlet from which the low oxygen gas blows out from the low oxygen gas supply device is directed to the outer peripheral surface of the image carrier.
According to a tenth aspect of the present invention, there is provided a charging roller that is disposed at a position facing the outer peripheral surface of the image carrier and rotates in a counter direction with respect to the image carrier surface movement direction at the facing position; A casing member that surrounds the casing member, and is formed between the edge of the casing member and the outer peripheral surface of the image carrier member, which is positioned downstream of the charging roller along the rotation direction of the image carrier member. An introduction port into which low oxygen gas is introduced, and the casing member positioned on the upstream side of the charging roller along the rotation direction of the image carrier and opposite to the side on which the introduction port is formed A charging device that is formed between the edge of the image carrier and the outer peripheral surface of the image carrier and exhausts the low oxygen gas introduced into the casing member, and the outer peripheral surface of the image carrier Electrostatic latent image formed on And a developing device that forms a toner image by supplying toner, and a process cartridge that is detachably attached to the image forming apparatus includes a low oxygen gas supply device that supplies low oxygen gas from the introduction port The low oxygen gas blowing direction from the outlet from which the low oxygen gas blows out from the low oxygen gas supply device is directed to the upstream side in the rotation direction of the image carrier along the outer peripheral surface of the image carrier. Features.
According to an eleventh aspect of the present invention, in the process cartridge according to the ninth or tenth aspect, the side opposite to the opening side in the longitudinal direction of the casing member is curved along the outer peripheral surface of the charging roller.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will 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.
[0036]
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.
[0037]
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.
[0038]
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
[0039]
Next, details of the process cartridge 3 will be described with reference to FIG.
[0040]
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).
[0041]
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 Alternatively, 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 of these materials can be used.
[0042]
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.
[0043]
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. This occurs mainly on the upstream side of the closest approach position with the charging roller 15 along the rotation 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.
[0044]
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.
[0045]
The cleaning device 12 includes a cleaning blade 12a that abuts with a counter with respect to the rotation direction of the photosensitive member 9, and a waste toner box 12b that stores the cleaned toner particles as waste toner.
[0046]
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. The supply pipe 13b and the blower outlet 13c which is provided in the front-end | tip part of the supply pipe 13b and blows out low oxygen gas are 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.
[0047]
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.
[0048]
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 to the core metal 15 a of the charging roller 15 from the charging bias application power source, 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.
[0049]
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.
[0050]
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.
[0051]
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.
[0052]
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.
[0053]
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
[0054]
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. 4, 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 center direction of the charging roller 15, and there is a gap between the edge of the casing member 16 facing the outer peripheral surface of the photoconductor 9 and the outer peripheral surface of the photoconductor 9. An introduction port 18 positioned upstream of the charging roller 15 along the rotation direction of the photoconductor 9 and an exhaust port 19 positioned downstream of the charging roller 15 along the rotation direction of the photoconductor 9 are formed. Yes. The introduction port 18 and the exhaust port 19 are formed to face the entire region along the axial direction of the charging roller 15. The clearance between the edge of the casing member 16 and the outer peripheral surface of the photoreceptor 9 at the inlet 18 and the outlet 19 is set to about 3 mm. As a means for maintaining the casing member 16 and the outer peripheral surface of the photosensitive member 9 in a non-contact manner, a known interval regulating member such as a roller can be used.
[0055]
On the upstream side of the charging device 10 along the rotation direction of the photoconductor 9, a blowout port 13 c of the low oxygen gas supply device 13 is disposed in the vicinity of the introduction port 18. As with the introduction port 18, the air outlet 13 c is formed to face the entire region along the axial direction of the charging roller 15. Further, the air outlet 13 c is positioned so that the blowing direction of the low oxygen gas from the air outlet 13 c faces the outer peripheral surface of the photoconductor 9.
[0056]
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 is generated in the follower direction along the rotation direction of the charging roller 15 as shown by a broken line inside the casing member 16 and on the outer periphery of the charging roller 15. Yes.
[0057]
If low oxygen gas is blown out from the outlet 13c located in the vicinity of the upstream side of the inlet 18 of the charging device 10 along the rotation direction of the photosensitive member 9 in such a state, a part of the low oxygen gas is introduced. It is introduced into the casing member 16 from the port 18. Introduction of the low oxygen gas blown out from the blowout port 13 c into the casing member 16 through the introduction port 18 is promoted by riding on the airflow generated around the photoconductor 9 as the photoconductor 9 rotates.
[0058]
The low oxygen gas introduced into the casing member 16 from the introduction port 18 enters the discharge region a on the upstream side where the photoconductor 9 and the charging roller 15 are opposed to each other on the introduction port 18 side, and then rotates the charging roller 15. Along with the airflow A generated around the charging roller 15, it flows in the casing member 16 toward the exhaust port 19, and enters the discharge region b on the downstream side where the photoconductor 9 and the charging roller 15 face each other. Thereafter, the air is exhausted from the exhaust port 19 to the outside of the casing member 16. For this reason, the low oxygen gas enters the upstream and downstream discharge areas a and b between the charging roller 15 and the photosensitive member 9, and the ventilation property to the low oxygen gas in the discharge areas a and b is high. Thus, the generation of discharge products due to the discharge phenomenon in the discharge regions a and b is reduced or prevented.
[0059]
Between the charging roller 15 and the inner peripheral surface of the casing member 16, it is only necessary to secure a space for the airflow A that is accompanied by the rotation of the charging roller 15 to flow, and the casing member 16 and the charging device 10 can be downsized. be able to.
[0060]
Further, since the blowing direction of the low oxygen gas blown out from the outlet 13 is directed to the outer peripheral surface of the photoconductor 9, it adheres to the outer peripheral surface of the photoconductor 9 and opposes the charging roller 15 as the photoconductor 9 rotates. Oxygen carried to the discharge region a is peeled off from the outer peripheral surface of the photosensitive member 9 by the low oxygen gas blown out from the blower outlet 13c, so that entry of oxygen into the casing member 16 is reduced, and generation of discharge products accompanying discharge phenomenon is generated. Is further reduced.
[0061]
FIG. 5 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.
[0062]
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.
[0063]
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 blown out from the outlet 13c through the supply pipe 13b from the inside of the low oxygen gas storage portion 13a is introduced from the inlet 18 by opening the shutter 17. The time required for the casing member 16 to be filled is, 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.
[0064]
A second embodiment of the present invention will be described with reference to FIG. The same portions as those described in FIGS. 1 to 6 are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following embodiments).
[0065]
In the charging device 31 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. An introduction port 18 is formed on the upstream side of the casing member 16 along the rotation direction of the photoconductor 9, an exhaust port 19 is formed on the downstream side, and an air outlet 13 c is disposed in the vicinity of the introduction port 18.
[0066]
As the charging roller 15 rotates in the follower direction with respect to the photosensitive member 9, an airflow B1 is generated in the casing member 16 along the rotation direction of the charge roller 15 as indicated by a broken line. .
[0067]
If low oxygen gas blows out from the blower outlet 13c in this state, a part of the low oxygen gas is introduced into the casing member 16 from the inlet 18. When the low oxygen gas is introduced into the casing member 16 from the introduction port 18, in addition to the air flow B <b> 1 described above, the introduced low oxygen gas flows through the casing member 16 from the introduction port 18 side to the exhaust port 19 side. B2 is generated along the inner peripheral surface of the casing member 16. When the low-oxygen gas flow B2 reaches the exhaust port 19 side, a part of the low-oxygen gas is exhausted from the exhaust port 19 to the outside of the casing member 16 and another part of the low-oxygen gas is introduced on the air flow B1. Return to mouth 18 side.
[0068]
In this way, the low oxygen gas circulates in the casing member 16 so that the low oxygen gas enters the upstream discharge area a and the downstream discharge area b between the charging roller 15 and the photosensitive member 9. And the ventilation property to the low oxygen gas in the discharge areas a and b becomes high, and the generation of discharge products accompanying the discharge phenomenon in these discharge areas a and b is reduced or prevented.
[0069]
A third embodiment of the present invention will be described with reference to FIG. In the charging device 41 of the present embodiment, the rotation direction of the charging roller 15 is the counter direction with respect to the rotation direction of the photosensitive member 9 as in the first embodiment, but is formed in the charging device 41. The positions of the introduction port 18 and the exhaust port 19 are reversed, the introduction port 18 is formed on the downstream side of the charging device 41 along the rotation direction of the photoconductor 9, and the charging device 41 along the rotation direction of the photoconductor 9. An exhaust port 19 is formed on the upstream side.
[0070]
The air outlet 13c of the low oxygen gas supply device 13 is positioned on the downstream side of the charging device 41 along the rotation direction of the photoconductor 9, and the blowing direction of the low oxygen gas from the air outlet 13c is on the outer peripheral surface of the photoconductor 9. Along the rotation direction upstream of the photoconductor 9.
[0071]
As the charging roller 15 rotates in the counter direction with respect to the photoreceptor 9 as indicated by an arrow, an airflow C1 is generated in the casing member 16 along the rotation direction of the charging roller 15 as indicated by a broken line. ing.
[0072]
If low oxygen gas blows out from the blower outlet 13c in this state, a part of the low oxygen gas is introduced into the casing member 16 from the inlet 18. When the low oxygen gas is introduced into the casing member 16 from the introduction port 18, the introduced low oxygen gas flows in the casing member 16 from the introduction port 18 side to the exhaust port 19 side in addition to the above-described air flow C2. C2 is generated along the inner peripheral surface of the casing member 16. When the low-oxygen gas flow C2 reaches the exhaust port 19 side, a part of the low-oxygen gas is exhausted from the exhaust port 19 to the outside of the casing member 16 and a part of the low-oxygen gas rides on the air flow C1 and enters the introduction port 18. Return to the side.
[0073]
In this way, the low oxygen gas circulates in the casing member 16 so that the low oxygen gas enters the upstream discharge area a and the downstream discharge area b between the charging roller 15 and the photosensitive member 9. And the ventilation property to the low oxygen gas in the discharge areas a and b becomes high, and the generation of discharge products accompanying the discharge phenomenon in these discharge areas a and b is reduced or prevented.
[0074]
A fourth embodiment of the present invention will be described with reference to FIG. In the charging device 51 of the present embodiment, the rotation direction of the charging roller 15 is the rotating direction with respect to the rotation direction of the photoconductor 9 as in the second embodiment. The positions of the introduction port 18 and the exhaust port 19 formed in the charging device 51 are the same as those in the third embodiment, and the introduction port is provided downstream of the charging device 51 along the rotation direction of the photosensitive member 9. 18 is formed, and an exhaust port 19 is formed on the upstream side of the charging device 51 along the rotation direction of the photosensitive member 9. The blowout port 13c of the low oxygen gas supply device 13 is positioned on the downstream side of the charging device 51 along the rotation direction of the photoconductor 9 as in the third embodiment, and the low oxygen gas from the blowout port 13c. Is directed toward the upstream side of the rotation direction of the photoconductor 9 along the outer peripheral surface of the photoconductor 9.
[0075]
As the charging roller 15 rotates in the follower direction with respect to the photosensitive member 9, an airflow D that is rotated along the rotation direction of the charge roller 15 is generated in the casing member 16 as indicated by a broken line. .
[0076]
If low oxygen gas blows out from the blower outlet 13c in this state, a part of the low oxygen gas is introduced into the casing member 16 from the inlet 18. The low oxygen gas introduced into the casing member 16 from the introduction port 18 enters the discharge region b on the downstream side where the photoconductor 9 and the charging roller 15 are opposed to each other on the introduction port 18 side, and then enters the periphery of the charging roller 15. It rides on the generated air flow D and flows in the casing member 16 toward the exhaust port 19, enters the upstream discharge region a where the photosensitive member 9 and the charging roller 15 face each other, and then enters the casing from the exhaust port 19. Exhaust to the outside of the member 16.
[0077]
For this reason, the entry of low oxygen gas into the discharge areas a and b between the charging roller 15 and the photosensitive member 9 and the ventilation to the low oxygen gas in the discharge area become high, and the discharge product accompanying the discharge phenomenon. Occurrence is reduced or prevented.
[0078]
A fifth embodiment of the present invention will be described with reference to FIG. The process cartridge 61 of the present embodiment includes the photosensitive member 9, the charging device 51, the developing device 11, and the cleaning device 12, but the process cartridge 3 of each of the embodiments described above in that the low oxygen gas supply device 13 is not included. And the structure is different.
[0079]
In the image forming apparatus using the process cartridge 61 of the present embodiment, the low oxygen gas supply device 62 is provided on the apparatus main body side of the image forming apparatus. The low oxygen gas supply device 62 includes a low oxygen gas storage portion 62a for storing low oxygen gas, a supply pipe 62b to which low oxygen gas is supplied, and a blowout port 62c that is provided at the tip of the supply pipe 62b and blows out the low oxygen gas. It has. The air outlet 62c is positioned on the downstream side of the charging device 51 along the rotation direction of the photosensitive member 9 in a state where the process cartridge 61 is set in the image forming apparatus main body.
[0080]
According to the present embodiment, it is not necessary to replace the low oxygen gas supply device 62 integrally when replacing the process cartridge 61, and the low oxygen gas supply device 62 can be replaced separately from the process cartridge 61 as necessary. Yes. Thereby, it is not necessary to match the lifetimes of the process cartridge 61 and the low oxygen gas supply device 62, the degree of freedom in designing the process cartridge 61 and the low oxygen gas supply device 62 is increased, and the cost can be reduced. .
[0081]
A sixth embodiment of the present invention will be described with reference to FIG. The process cartridge 71 of the present embodiment includes the photosensitive member 9, the charging device 10, the developing device 11, and the cleaning device 12, but the process cartridge 3 of each of the embodiments described above in that the low oxygen gas supply device 13 is not included. And the structure is different.
[0082]
In the image forming apparatus using the process cartridge 71 of the present embodiment, the low oxygen gas supply device 72 is provided on the apparatus main body side of the image forming apparatus. The low oxygen gas supply device 72 includes a low oxygen gas storage portion 72a for storing low oxygen gas, a supply pipe 72b to which low oxygen gas is supplied, and an outlet 72c that is provided at the tip of the supply pipe 72b and blows out the low oxygen gas. It has. The air outlet 72c is positioned on the upstream side of the charging device 10 along the rotation direction of the photosensitive member 9 in a state where the process cartridge 71 is set in the image forming apparatus main body.
[0083]
According to the present embodiment, when replacing the process cartridge 71, it is not necessary to replace the low oxygen gas supply device 72 integrally, and if necessary, the low oxygen gas supply device 72 can be replaced separately from the process cartridge 71. Yes. Thereby, it is not necessary to match the lifetimes of the process cartridge 71 and the low oxygen gas supply device 72, the degree of freedom in designing the process cartridge 31 and the low oxygen gas supply device 72 is increased, and the cost can be reduced. .
[0084]
In the first to fourth embodiments described above, the low oxygen gas supply device 13 is provided in the process cartridge 3, and in the fifth and sixth embodiments, the low oxygen gas supply devices 62 and 72 are provided. Is provided on the main body side of the image forming apparatus. Of these low oxygen gas supply devices, only the low oxygen gas storage section is provided on the main body side of the image forming apparatus, and the supply pipe and the outlet are provided as a process. It is good also as a structure provided in a cartridge.
[0085]
【The invention's effect】
  Claim1 to 16According to the described invention, when the low oxygen gas is introduced into the casing member from the introduction port, the low oxygen gas rides on the air current generated around the charging roller as the charging roller rotates, and moves inside the casing member. Since the air is exhausted from the exhaust port to the outside of the casing member, ventilation to low oxygen gas is enhanced throughout the casing member, and the discharge region between the charging roller in the casing member and the image carrier is reduced to low oxygen. Generation | occurrence | production of the discharge product accompanying a discharge phenomenon by being filled with gas can be reduced.
[0086]
  Claim1According to the described invention,The charging roller rotates in a counter direction with respect to the image carrier, the introduction port is formed on the upstream side of the charging roller along the rotation direction of the image carrier, and the exhaust port is a rotation direction of the image carrier. The low oxygen gas enters the upstream and downstream discharge areas between the charging roller and the image carrier, and the low oxygen gas in the discharge area. As a result, the ventilation of the battery becomes higher, and the generation of discharge products accompanying the discharge phenomenon can be reduced.
[0087]
  Claim2According to the described invention,The charging roller rotates in a rotating direction with respect to the image carrier, the introduction port is formed on the downstream side of the charging roller along the rotation direction of the image carrier, and the exhaust port is a rotation of the image carrier. Since it is formed on the upstream side of the charging roller along the direction, the low oxygen gas enters the discharge area on the downstream side and the upstream side between the charging roller and the image carrier, and low oxygen in the discharge area. The ventilation property to gas becomes high, and the generation of discharge products accompanying the discharge phenomenon can be reduced.
[0088]
  According to a fourth aspect of the present invention, in the charging device according to the first aspect, the voltage applied to the charging roller is a DC voltage.RuTherefore, the discharge region located on the upstream side between the charging roller and the image carrier is easily filled with the low oxygen gas, and the generation of discharge products accompanying the discharge phenomenon can be reduced.
[0089]
According to the process cartridge of the fifth aspect of the present invention, since the charging device according to any one of the first to fourth aspects is provided, the charging apparatus is the same as the invention according to any one of the first to fourth aspects. It is possible to reduce the generation of discharge products accompanying the discharge phenomenon.
[0090]
According to the invention of claim 6, in the process cartridge of claim 5, since the low oxygen gas supply device for supplying low oxygen gas from the inlet is provided, the low oxygen gas supply device is a process cartridge. They can be exchanged as a unit, and handling can be improved.
[0091]
According to a seventh aspect of the present invention, in the process cartridge according to the sixth aspect, the outlet from which the low oxygen gas blows out from the low oxygen gas supply device is located upstream of the charging roller along the rotation direction of the image carrier. Since the low oxygen gas blowing direction from the blowout port is directed to the outer peripheral surface of the image carrier, the image carrier is attached to the outer peripheral surface of the image carrier. The oxygen transported to the discharge area facing the charging roller with the rotation of the toner can be peeled off from the outer peripheral surface of the image carrier by the low oxygen gas blown out from the blower outlet, thereby reducing the entry of oxygen into the casing member. Generation of discharge products accompanying the discharge phenomenon can be further reduced.
[0092]
According to an eighth aspect of the present invention, in the process cartridge according to the sixth aspect, the outlet from which the low oxygen gas blows out from the low oxygen gas supply device is downstream of the charging roller along the rotation direction of the image carrier. Since the low oxygen gas blowing direction from the blowout port is directed to the upstream side in the rotation direction of the image carrier along the outer peripheral surface of the image carrier. Low oxygen gas can be satisfactorily introduced into the casing member from the inlet located downstream in the rotation direction of the carrier.
[0093]
  Claim12According to the image forming apparatus of the invention described in claims 6,11Therefore, the generation of discharge products during discharge for charging the image bearing member is reduced, and deterioration of image quality due to the influence of the discharge products can be prevented.
[0094]
  Claim13According to the image forming apparatus of the invention described above, the process cartridge according to claim 5 and the air outlet are positioned on the inlet side formed on the upstream side of the charging roller along the rotation direction of the image carrier. Since the low oxygen gas supply direction from the lever outlet is directed to the outer peripheral surface of the image carrier, the low oxygen gas supply device is replaced as a unit when the process cartridge is replaced. The low-oxygen gas blows out from the blowout port of oxygen that adheres to the outer peripheral surface of the image carrier and is carried to the discharge area facing the charging roller as the image carrier rotates. It can peel off from an outer peripheral surface, can reduce the penetration | invasion of oxygen into a casing member, and can further reduce generation | occurrence | production of the discharge product accompanying a discharge phenomenon.
[0095]
  Claim14According to the image forming apparatus of the present invention, the process cartridge according to claim 5 and the air outlet are positioned on the inlet side formed on the downstream side of the charging roller along the rotation direction of the image carrier. And a low oxygen gas supply device in which the blowing direction of the low oxygen gas from the lever outlet is directed in the direction along the outer peripheral surface of the image carrier. Therefore, the low oxygen gas supply device is integrated when the process cartridge is replaced. The low oxygen gas can be satisfactorily introduced into the casing member from the inlet located downstream in the rotation direction of the image carrier.
[0096]
  Claim15According to the described invention, the claims12 to 14The image forming apparatus according to any one of claims 1 to 3, wherein a voltage is applied to the charging roller after a lapse of a predetermined time after the charging roller rotates in a predetermined direction and the supply of the low oxygen gas from the low oxygen gas supply device is started. Since the casing member is filled with low oxygen gas when a voltage is applied to the charging roller, the generation of discharge products during charging of the image carrier can be reliably reduced.
[0097]
  Claim16According to the described invention, the claims12 to 14The low-oxygen gas is supplied from the low-oxygen gas supply device after a lapse of a predetermined time after the charging roller is rotated in a predetermined direction, and the supply of the low-oxygen gas is started. Since there is a control means for starting the voltage application to the charging roller after a predetermined time later, the casing member is filled with low oxygen gas when the voltage is applied to the voltage to the charging roller. The generation of discharge products during charging can be reliably reduced, and the low oxygen gas is effectively utilized by supplying the low oxygen gas after rotating the charging roller and generating an air flow around the charging roller. be able to.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a color printer according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram showing a process cartridge attached / detached state.
FIG. 3 is an enlarged sectional view showing a process cartridge.
FIG. 4 is a cross-sectional view showing the charging device further enlarged.
FIG. 5 is a block diagram showing an electrical connection of a portion related to supply of low oxygen gas in the printer.
FIG. 6 is a flowchart illustrating the supply of low oxygen gas.
FIG. 7 is a cross-sectional view illustrating a charging device according to a second embodiment of the present invention.
FIG. 8 is a cross-sectional view illustrating a charging device according to a third embodiment of the present invention.
FIG. 9 is a cross-sectional view showing a charging device according to a fourth embodiment of the present invention.
FIG. 10 is a cross-sectional view showing a process cartridge according to a fifth embodiment of the present invention.
FIG. 11 is a cross-sectional view showing a process cartridge according to a sixth embodiment of the present invention.
[Explanation of symbols]
3 Process cartridge
5 Transfer device
7 Optical writing device
8 Fixing device
9 Image carrier
10 Charging device
11 Development device
13 Low oxygen gas supply device
13c outlet
15 Charging roller
16 Casing member
18 Inlet
19 Exhaust port
31 Charging device
41 Charging device
51 Charging device
61 Process cartridge
62 Low oxygen gas supply device
62c outlet
71 Process cartridge
72 Low oxygen gas supply device
72c outlet

Claims (9)

An image carrier;
A charging roller disposed at a position facing the outer peripheral surface of the image carrier and rotating so that the surface moves in the counter direction with respect to the surface movement direction of the image carrier at the facing position, and a casing member surrounding the charging roller And is formed between the edge of the casing member and the outer peripheral surface of the image carrier and located on the upstream side of the charging roller along the rotation direction of the image carrier, An introduction port through which gas is introduced; and an edge of the casing member located on the downstream side of the charging roller along the rotation direction of the image carrier and opposite to the side on which the introduction port is formed. A charging device having an exhaust port formed between the outer peripheral surface of the image carrier and exhausted with the low oxygen gas introduced into the casing member ;
A developing device for supplying toner to an electrostatic latent image formed on the outer peripheral surface of the image carrier to form a toner image;
A process cartridge having a low oxygen gas supply device for supplying low oxygen gas from the introduction port and detachably attached to the image forming apparatus. An image carrier;
A charging roller that is disposed at a position facing the outer peripheral surface of the image carrier and rotates so that the surface moves in a rotating direction with respect to the moving direction of the surface of the image carrier at the facing position, and a casing surrounding the charging roller A member is formed on the downstream side of the charging roller along the rotation direction of the image carrier, and is formed between the edge of the casing member and the outer peripheral surface of the image carrier, and is formed in the casing member. An introduction port through which oxygen gas is introduced, and an edge portion of the casing member that is located upstream of the charging roller along the rotation direction of the image carrier and opposite to the side on which the introduction port is formed A charging device having an exhaust port formed between the outer peripheral surface of the image carrier and the low oxygen gas introduced into the casing member .
A developing device for supplying toner to an electrostatic latent image formed on the outer peripheral surface of the image carrier to form a toner image;
A process cartridge having a low oxygen gas supply device for supplying low oxygen gas from the introduction port and detachably attached to the image forming apparatus. Longitudinal opposite side to the opening side in the direction, the process cartridge according to claim 1 or 2 wherein is curved along the outer circumferential surface of the charging roller of the casing member. The process cartridge according to claim 1, wherein the voltage applied to the charging roller is a DC voltage . A blowout port from which low oxygen gas blows out from the low oxygen gas supply device is positioned on the introduction port side formed on the upstream side of the charging roller along the rotation direction of the image carrier, and low oxygen from the blowout port. the process cartridge according to claim 1, wherein the blowing direction of the gas is directed to the outer peripheral surface of the image bearing member. A blowout port from which the low oxygen gas blows out from the low oxygen gas supply device is positioned on the introduction port side formed on the downstream side of the charging roller along the rotation direction of the image carrier, and the low oxygen from the blowout port The process cartridge according to claim 2, wherein a gas blowing direction is directed to an upstream side in the rotation direction of the image carrier along the outer peripheral surface of the image carrier. And a process cartridge according to any one of claims 1 to 6, an optical writing device for forming an electrostatic latent image on the image bearing member provided in said process cartridge, formed on the outer peripheral surface of the image bearing member An image forming apparatus comprising: a transfer device that transfers the toner image transferred onto a recording medium; and a fixing device that fixes the toner image transferred onto the recording medium. According to claim 7, wherein the charging roller has a control means for the starting the 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 while rotating in a predetermined direction 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 in a predetermined direction, and the charging roller is supplied 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 7, further comprising a control unit that starts voltage application.

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