JP2004301958A - Charging device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent oxygen from entering a casing member from between an outer peripheral surface of an image carrier and an edge of the casing member facing an image carrier when the generation of discharge products is reduced by introducing low-oxygen gas into the casing member surrounding a discharging roller. <P>SOLUTION: This discharging device is configured to introduce the low-oxygen gas into the casing member 16 by surrounding the discharging roller 15 disposed opposite the outer peripheral surface of the image carrier 9 with the casing member 16 and fitting a flexible upstream seal 18 which is brought into slide contact with the outer peripheral surface of the image carrier 9 to an upstream edge of the casing member 16 in the rotating direction of the image carrier 9. Consequently, the introduction of the low-oxygen gas into the casing member 16 raises the pressure in the casing member 16 and the rise in pressure presses the upstream seal 18 against the outer peripheral surface of the image carrier 9, thereby preventing oxygen sticking on the outer peripheral surface of the image carrier 9 from entering the casing member 16 as the image carrier 9 rotates. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD 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 by using a discharge phenomenon, and a discharge product such as ozone and nitrogen oxide is generated by the discharge phenomenon. When ozone stays in the image forming apparatus at a high concentration, the surface of the image carrier is oxidized, causing a decrease in 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 shortened.
[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 a low oxygen gas into the cover. An invention has been proposed (for example, see 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 measured from the gap between the edge of the case surrounding the charging roller facing the image carrier and the outer peripheral surface of the image carrier. Oxygen adhering to the surface enters into the case with the rotation of the image carrier, which causes a discharge product.
[0006]
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 occurs in that the outer peripheral surface of the image carrier is damaged by contact with the elastic body.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to reduce the generation of discharge products by introducing a low oxygen gas into a casing member surrounding a charging roller, and to provide an outer peripheral surface of an image carrier and an edge of a casing member facing the image carrier. To prevent oxygen from entering the casing member from between the above, and further reduce the generation of discharge products in the casing member.
[0008]
[Means for Solving the Problems]
The charging device according to claim 1, wherein the charging roller is disposed at a position facing an outer peripheral surface of the image carrier, and is rotatable around an axis parallel to a rotation axis of the image carrier. A casing member enclosing the casing member, and a front end portion of the casing member, which is attached to an upstream edge of the image carrier along the rotation direction of the image carrier, faces a downstream side of the image carrier in a rotation direction of the image carrier. A flexible upstream seal that is curved and slidably contacts the outer peripheral surface of the image carrier; and an inlet formed in the casing member and through which low oxygen gas is introduced into the casing member. .
[0009]
Here, the “low oxygen gas” includes a nitrogen gas and a rare gas, and may also include a gas having a lower oxygen concentration than the atmosphere. 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]
Therefore, when the low oxygen gas is introduced into the casing member from the inlet, the oxygen concentration in the casing member is reduced, and the generation of discharge products due to the discharge phenomenon is reduced. Further, the pressure in the casing member increases due to the introduction of the low oxygen gas into the casing member, and the pressure increase causes the upstream seal to be pressed against the outer peripheral surface of the image carrier. Oxygen is prevented from entering the casing member as the image carrier rotates, and the generation of discharge products due to the discharge phenomenon is further reduced.
[0011]
According to a second aspect of the present invention, in the charging device according to the first aspect, a front end portion of the casing member, which is attached to a downstream edge of the image carrier along a rotation direction of the image carrier, faces the image carrier. A flexible downstream seal that curves toward the downstream side in the rotation direction of the image carrier and slides on the outer peripheral surface of the image carrier;
[0012]
Therefore, since the upstream side and the downstream side of the casing member are closed by the upstream side seal and the downstream side seal, the pressure in the casing member can be increased, and the pressing force of the upstream side seal against the outer peripheral surface of the image bearing member can be increased. And the oxygen adhering to the outer peripheral surface of the image carrier is further prevented from entering the casing member as the image carrier rotates. Further, the downstream seal prevents entry of oxygen into the casing member from between the downstream edge of the casing member and the outer peripheral surface of the image carrier. When the pressure in the casing member rises to a predetermined value, the downstream seal is partially separated from the outer peripheral surface of the image carrier to perform exhaust.
[0013]
According to a third aspect of the present invention, in the charging device according to the first or second aspect, the introduction port is formed in a side surface of the casing member in a direction along an axis of the charging roller.
[0014]
Accordingly, the low oxygen gas introduced into the casing member flows quickly along the axial direction of the charging roller, and the upstream seal is pressed against the outer peripheral surface of the image carrier quickly.
[0015]
According to a fourth aspect of the present invention, there is provided a process cartridge which supplies toner to an image carrier, the charging device according to any one of the first to third aspects, and an electrostatic latent image formed on an outer peripheral surface of the image carrier. And a developing device for forming a toner image by the image forming apparatus, and is detachably attached to the image forming apparatus.
[0016]
Therefore, according to this process cartridge, the generation of discharge products due to the discharge phenomenon is reduced, as in the first aspect of the present invention.
[0017]
According to a fifth aspect of the present invention, in the process cartridge according to the fourth aspect, there is provided a low-oxygen gas supply device connected to the inlet and supplying a low-oxygen gas from the inlet.
[0018]
Therefore, since the low oxygen gas supply device is integrated with the process cartridge, the low oxygen gas supply device can be exchanged with the process cartridge and the like, and the handling property is improved.
[0019]
According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising: the process cartridge according to the fifth aspect; an optical writing device that forms an electrostatic latent image on the image carrier provided in the process cartridge; A transfer device for transferring the toner image formed on the outer peripheral surface of the body 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 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.
[0021]
According to a seventh aspect of the present invention, there is provided an image forming apparatus, wherein the process cartridge according to the fourth aspect, a low oxygen gas supply device connected to the introduction port, and the image carrier provided in the process cartridge are electrostatically charged. An optical writing device for forming a latent image, a transfer device for transferring a toner image formed on the outer peripheral surface of the image carrier to a recording medium, a fixing device for fixing the toner image transferred to the recording medium, Having.
[0022]
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. 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 replacing the process cartridge.
[0023]
According to an eighth aspect of the present invention, in the image forming apparatus according to the sixth or seventh aspect, the predetermined time after the supply of the low oxygen gas from the low oxygen gas supply device is started while the charging roller rotates, the There is a control unit for starting voltage application to the charging roller.
[0024]
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 when the image carrier is charged is reliably reduced.
[0025]
According to a ninth aspect of the present invention, in the image forming apparatus according to the sixth or seventh aspect, the low oxygen gas supply device supplies the low oxygen gas after a lapse of a predetermined time after rotating the charging roller in a predetermined direction. And control means for starting voltage application to the charging roller after a lapse of a predetermined time after the supply of the low oxygen gas is started.
[0026]
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 when the image carrier is charged is reliably reduced. Further, by supplying the low-oxygen gas after the airflow is generated around the charging roller by rotating the charging roller, the low-oxygen gas filling in the casing member can be quickly carried on the generated airflow. .
[0027]
BEST MODE FOR CARRYING OUT 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 as an image forming apparatus. In the apparatus main body 2 of the color printer 1, four process cartridges 3Y, 3C, 3M, and 3K, a transport belt 4, a transfer roller 5 as a transfer device, and a storage unit that stores a recording medium S such as recording paper or OHP paper. 6, optical writing devices 7Y, 7C, 7M, 7K, a fixing device 8, and the like. The subscripts of 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 the toner colors (Y is yellow, C is cyan, and C is cyan, respectively). M means magenta and K means black), and the suffix will be omitted as necessary.
[0028]
The process cartridges 3 form toner images of different colors, and as shown in FIG. 3, a drum-shaped photosensitive member 9 serving as an image carrier, and a charging device for uniformly charging the surface of the photosensitive member 9 10, a developing device 11 for supplying a toner to an electrostatic latent image formed on the outer peripheral surface of the photoconductor 9 to form a toner image, and a residual amount remaining on the outer peripheral surface of the photoconductor 9 after transferring the toner image to the recording medium S The cleaning device 12 and the low-oxygen gas supply device 13 that collect the collected toner are configured. Each of the process cartridges 3 is detachably attached to the outside of the apparatus main body 2 after rotating the transport belt 4 to the open position as shown in FIG.
[0029]
The optical writing device 7 includes a polygon mirror or the like, and exposes the outer peripheral surface of the photoconductor 9 according to image information to form 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 photoconductor 9 in each process cartridge 3 is driven to rotate, the photoconductor 9 is exposed by each optical writing device 7 in accordance with the image information of each color, and an electrostatic latent image is formed on the outer peripheral surface of the photoconductor 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 conveyor belt 4 is conveyed at a timing to form a toner image and the toner image on the photoconductor 9 is transferred onto the recording medium S one after another 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 fixing processing. The recording medium S after the fixing processing is discharged onto a discharge tray 14 formed on the upper surface of the apparatus main body 2. You.
[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 a direction indicated by an arrow (counterclockwise) by a rotation driving 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 urethane foam layer 15b in which a urethane resin, carbon black as conductive particles, a sulfide agent, a foaming agent, etc. are prescribed is formed on a core metal 15a in a roller shape. , Is arranged in non-contact with 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 medium resistance layer formed on the cored bar 15a in the charging roller 15 is not limited to the above, but may be urethane, ethylene, propylene, diene polyethylene (EPDM), butadiene acrylonitrile rubber (NBR), or silicone rubber. A rubber material in which a conductive substance such as carbon black or metal oxide is dispersed in isoprene rubber or the like for resistance adjustment, or a foamed material thereof can be used.
[0034]
A DC voltage of −400 V and an AC voltage having an amplitude of 900 V and a frequency of 1 kHz are applied to the core metal 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, so that the photosensitive drum 9 is exposed to light. The outer peripheral surface of the body 9 is charged to about -400V.
[0035]
The voltage applied to the metal core 15a of the charging roller 15 may be a DC voltage only. When only the DC voltage is applied to the metal core 15 a of the charging roller 15, the discharge phenomenon that occurs between the photoconductor 9 and the charging roller 15 to charge the photoconductor 9 causes the discharging phenomenon of the photoconductor 9. This occurs mainly on the upstream side of the closest position to the charging roller 15 along the rotation direction. The reason is that the discharge is performed on the upstream side, the potential difference between the photosensitive member 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. The developing device 11 includes a developing roller 11a that rotates clockwise and comes into contact with the photoconductor 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. It has an elastic blade 11c for negatively charging the toner particles by friction while regulating the thickness of the particles, and a stirring member 11d for moving the toner particles in the developing device 11 toward the supply roller 11b while stirring.
[0037]
The cleaning device 12 has a cleaning blade 12a that abuts on the counter of the rotation direction of the photoconductor 9, 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 a low-oxygen gas such as a nitrogen gas or a rare gas into the casing member 16. The low-oxygen gas storage unit 13 a that stores the low-oxygen gas is supplied with the 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 unit 13a and the supply pipe 13b.
[0039]
Here, the operation of forming a toner image 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 photoconductor 9. Is converted.
[0040]
Prior to exposure from the optical writing device 7, the photoconductor 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 photoconductor 9. At this time, a DC voltage of −400 V and an AC voltage having an amplitude of 900 V and a frequency of 1 kHz are applied to the core metal 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. As a result, the outer peripheral surface of the photoconductor 9 is charged to about -400V.
[0041]
The optical writing device 7 (7Y, 7C, 7M, 7K) performs exposure on the charged photoreceptor 9 in accordance with write data. That is, the potential of the image portion is changed by the light irradiation to generate a difference from the potential of the non-image portion not irradiated with the light, and an electrostatic latent image is formed by this potential contrast.
[0042]
The electrostatic latent image formed on the photoreceptor 9 by the optical writing device 7 is developed by a developing device 11, and the developing device 11 forms a toner image on the photoreceptor 9 by a contact type non-magnetic one-component developing method. I do. Specifically, the developing roller 11a is rotated clockwise, and the supply roller 11b made of an elastic body that rotates clockwise is brought into contact with the developing roller 11a, so that the toner particles on the supply roller 11b are removed from the developing roller 11a. 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 are conveyed to a portion facing the photoconductor 9 according to the rotation of the developing roller 11a.
[0043]
At a portion where the developing roller 11a and the photosensitive member 9 are opposed to each other, a DC electric field 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 negatively charged. The toner particles thus selectively adhere to only the image portion on the photoreceptor 9 due to the DC electric field to form a toner image.
[0044]
The recording medium S is transported by the transport belt 4 at the timing when the toner image formed on the photoconductor 9 reaches the transfer area, which is a portion where the transfer roller 5 and the photoconductor 9 are opposed to each other. 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 photoconductor 9 without being transferred is cleaned by the cleaning device 12, and the outer peripheral surface of the cleaned photoconductor 9 is charged by the charging device 10 for the next image formation. You.
[0046]
Next, a structure related to the supply of the 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 facing the outer peripheral surface of the photoconductor 9 is not in contact with the outer peripheral surface of the photoconductor 9. Facing. A flexible upstream seal 18 is attached to an edge of the casing member 16 on the upstream side along the rotation direction of the photoconductor 9. The upstream side seal 18 is formed in a long shape extending along the axial direction of the charging roller 15, one end in a direction orthogonal to the long direction is fixed to an edge of the casing member 16, and the other end is fixed. The free end extends toward the photoreceptor 9. The length from the edge of the casing member 16 to the free end on the upstream side 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 photosensitive member 9. The free end of the side seal 18 is curved toward the downstream side in the rotation direction of the photoconductor 9 and is in sliding contact with the outer peripheral surface of the photoconductor 9.
[0047]
An inlet 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 place where the low oxygen gas is introduced from the low oxygen gas supply device 13 into the casing member 16, and is connected to a distal end of the supply pipe 13 b.
[0048]
During image formation, the photoconductor 9 rotates in the direction of the arrow (counterclockwise) and the charging roller 15 rotates in the counter direction. Along with the rotation of the charging roller 15, an airflow A is generated in the rotating direction of the charging roller 15 inside the casing member 16 and on the outer peripheral portion of the charging roller 15, as shown by a broken line. I have.
[0049]
In such a state, when low oxygen gas is introduced into the casing member 16 from the inlet 19, the low oxygen gas introduced into the casing member 16 flows 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 gas flow A to be in a low pressure state. Get in. The low-oxygen gas that has entered the discharge region a flows along the outer peripheral surface of the charging roller 15 on the airflow A, enters the downstream discharge region b between the charging roller 15 and the outer peripheral surface of the photoconductor 9, and Thereafter, the air is exhausted out of the casing member 16 from a gap between the edge of the casing member 16 and the outer peripheral surface of the photoconductor 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 inlet 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 near the inlet 19 increases, and the upstream side seal 18 causes the outer peripheral surface of the photoconductor 9 to move due to the increase in the pressure. Pressed against the surface.
[0050]
Here, the inside of the casing member 16 is filled with low-oxygen gas, and the low-oxygen gas enters the upstream discharge region a and the downstream discharge region b 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]
Further, the upstream seal 18 is pressed against the outer peripheral surface of the photosensitive member 9 by the pressure increase in the casing member 16 due to the low oxygen gas introduced into the casing member 16, so that the oxygen adhering to the outer peripheral surface of the photosensitive member 9 is exposed. The entry into the casing member 16 with the rotation of the body 9 can be prevented by the upstream seal 18, and the generation of discharge products due to the discharge phenomenon is further reduced or prevented.
[0052]
FIG. 6 is a block diagram showing an electrical connection of a 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 for rotating the printer, a voltage application switch 22 for applying a voltage to the charging roller 15, an actuator 23 for driving the shutter 17, a timer 24, a start key 25 for starting 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 based on the pressing of the start key 25 and a control program for performing an image forming operation. Have been.
[0053]
When supplying the low oxygen gas, first, it is determined whether or not the start key 25 has been pressed down (step S1). If the start key 25 has been pressed down, the drive motor 21 is driven (step S2). It is determined whether a predetermined time has elapsed after the driving of the drive motor 21 (step S3). After the predetermined time has elapsed, the actuator 23 is driven and the shutter 17 is opened (step S4). The predetermined time determined in step S3 is a time required for an airflow to be generated around the charging roller 15 due to the rotation of the charging roller 15, for example, a time required for the charging roller 15 to make 10 rotations.
[0054]
After the shutter 17 is opened in step S4, it is determined whether a predetermined time has elapsed (step S5), and after the predetermined time has elapsed, the voltage application switch 22 is turned on (step S6). The predetermined time determined in step S5 means that the low oxygen gas supplied from the inlet 19 through the supply pipe 13b from inside the low oxygen gas storage unit 13a into the casing member 16 when the shutter 17 is opened. This is the time required to be filled, for example, the time required for the charging roller 15 to make five rotations. 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 photoconductor 9 and the charging roller 15 with the application of the voltage. Be charged. At the time of this charging, the discharge regions a and b are filled with low oxygen gas, so that 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 processing of steps S <b> 2 to S <b> 6 described above. Control means for starting voltage application to the charging roller 15 after a predetermined time has elapsed, or supply of the low oxygen gas from the low oxygen gas supply device 13 after a predetermined time has elapsed after rotating the charging roller 15 in a predetermined direction. Then, control means for starting voltage application to the charging roller 15 after a lapse of a predetermined time after the supply of the low oxygen gas is started is executed.
[0055]
A second embodiment of the present invention will be described with reference to FIG. 1 to 7 are denoted by the same reference numerals, and description thereof will be omitted (the same applies to the following embodiments).
[0056]
The basic structure of the charging device 31 of the present embodiment is the same as that of the charging device 10 of the first embodiment, and is the surface of the casing member 16 on which the upstream seal 18 is attached, and the shaft of the charging roller 15. An introduction port 32 into which the low oxygen gas is introduced is formed at a substantially central portion along the center direction. The leading end of the supply pipe 13b is connected to the inlet 32.
[0057]
The low-oxygen gas introduced into the casing member 16 from the inlet 32 fills the casing member 16 and enters the upstream discharge region a and the downstream discharge region b to charge the photoconductor 9. The generation of discharge products due to the discharge phenomenon between the charging roller 15 and the photoconductor 9 is reduced or prevented. Further, the upstream seal 18 is pressed against the outer peripheral surface of the photosensitive member 9 by the pressure increase in the casing member 16 due to the low oxygen gas introduced into the casing member 16, so that the oxygen adhering to the outer peripheral surface of the photosensitive member 9 is exposed. The entry into the casing member 16 with the rotation of the body 9 can be prevented by the upstream seal 18, and the generation of discharge products due to a discharge phenomenon for charging the photoconductor 9 is further reduced, or Is prevented.
[0058]
A third embodiment of the present invention will be described with reference to FIG. The charging device 41 of the present embodiment is obtained by adding a flexible downstream seal 42 to the charging device 10 of the first embodiment.
[0059]
The downstream seal 42 is attached to a downstream edge of the casing member 16 along the rotation direction of the photoconductor 9, and is formed in a long shape extending along the axial direction of the charging roller 15. One end in a direction perpendicular to the longitudinal direction is fixed to an edge of the casing member 16, and the other end is a free end extending toward the photoconductor 9. The length dimension from the edge of the casing member 16 to the free end on the downstream side seal 42 is set to be larger than the distance between the edge of the casing member 16 and the outer peripheral surface of the photoconductor 9. The free end side of the side seal 42 is curved toward the downstream side in the rotation direction of the photoconductor 9 and is in sliding contact with the outer peripheral surface of the photoconductor 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 is prevented.
[0061]
Since the upstream and downstream sides of the casing member 16 along the rotation direction of the photoconductor 9 are closed by the upstream seal 18 and the downstream seal 42, a low oxygen gas is introduced into the casing member 16. In this case, the pressure inside the casing member 16 can be increased as compared with the case of the first embodiment. 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 enters the casing member 16 as the photoconductor 9 rotates. This is further prevented, and the generation of discharge products due to the discharge phenomenon for charging the photoconductor 9 is further reduced or prevented.
[0062]
Further, by providing the downstream seal 42, it is possible to prevent oxygen from entering the casing member 16 from the downstream side in the rotation direction of the photoconductor 9 in the casing member 16.
[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 and separates from the outer peripheral surface of the photoconductor 9. As a result, the exhaust is performed, and the pressure in the casing member 16 is automatically adjusted.
[0064]
A fourth embodiment of the present invention will be described with reference to FIG. In the charging device 51 of the present embodiment, the charging roller 15 is rotated by the photoconductor 9. For this reason, a gear mechanism or the like for transmitting the rotational force to the charging roller 15 is not required, and the structure is simplified. An upstream seal 18 is attached to an upstream edge of the casing member 16 along the rotation direction of the photoconductor 9, and an inlet is provided at one side surface of the casing member 16 near the upstream seal 18. 19 are formed.
[0065]
Further, a DC voltage is used as a voltage applied to the charging roller 15 to charge the photoconductor 9. For this reason, the discharge phenomenon between the photoconductor 9 and the charging roller 15 mainly occurs in the discharge region a on the upstream side along the rotation direction of the photoconductor 9. The reason is that the discharge is performed in the discharge region a on the upstream side, so that the photosensitive member 9 and the charging roller 15 are opposed to each other on the downstream side along the rotation direction of the photosensitive member 9 facing the charging roller 15. This is because the potential difference 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 the airflow A ′ causes oxygen to flow into the casing member 16 downstream of the casing member 16. 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, when the low oxygen gas is introduced from the inlet 19, the upstream discharge region a is filled with the low oxygen gas. Further, the upstream seal 18 is pressed against the outer peripheral surface of the photoconductor 9 by the pressure increase due to the introduced low oxygen gas, so that external oxygen is prevented from entering the discharge region a with the rotation of the photoconductor 9. You. Further, the introduction of the low oxygen gas prevents oxygen in the gas flow A 'from entering the discharge region a. As described above, generation of discharge products in the discharge region a is reduced or prevented.
[0068]
A fifth embodiment of the present invention will be described with reference to FIG. In the charging device 61 of the present embodiment, the charging roller 15 is rotated by the photoconductor 9. Therefore, a gear mechanism for transmitting the rotational force to the charging roller 15 is not required, 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 space 64a and the inner peripheral space 64b partitioned by the partition plate 63 communicate with each other on the upstream side and the downstream side along the rotation direction of the photoconductor 9 in the casing member 51.
[0069]
An upstream seal 18 is attached to an upstream edge of the casing member 62 along the rotation direction of the photosensitive member 9, and a downstream edge of the casing member 62 is located at a downstream edge of the photosensitive member 9 along the rotation direction. A seal 42 is attached.
[0070]
An introduction port through which the low-oxygen gas is introduced in communication with the outer-peripheral-side space 64a at a substantially central portion along the axial direction of the charging roller 15 on the surface of the casing member 62 on which the upstream seal 18 is attached. 65 are formed. The leading end of the supply pipe 13b is connected to the inlet 65.
[0071]
In such a configuration, the rotation of the charging roller 15 generates an airflow A ′ in a co-rotating direction in the inner peripheral side space 64 b around the charging roller 15, and the airflow A ′ is generated in the upstream side in the casing member 62. The air enters the outer peripheral space 64a at the end, and flows in the outer peripheral space 64a as a reverse airflow B. 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 as the airflow A 'in the rotating direction by the charging roller 15.
[0072]
When the low oxygen gas is introduced from the inlet 65 into the outer space 64a where the airflow 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 airflow B, it reaches the downstream discharge region b, then flows on the airflow A ′, flows in the inner peripheral space 64b, reaches the upstream discharge region b, and returns to the outer peripheral space b. 64a.
[0073]
Thereby, the casing member 62 is filled with the low oxygen gas, and the generation of discharge products due to the discharge phenomenon in the discharge regions a and b is reduced or prevented. When the low-oxygen gas is introduced into the casing member 62 and the pressure inside the casing member 62 rises, the upstream seal 18 is pressed against the outer peripheral surface of the photoconductor 9, and the oxygen adhering to the outer peripheral surface of the photoconductor 9 is Is prevented from entering the casing member 16 as the photoconductor 9 rotates, and the generation of discharge products due to the discharge phenomenon is further reduced or prevented.
[0074]
When the pressure in the casing member 62 rises to a predetermined value due to the introduction of the low oxygen gas into the casing member 62, the downstream side seal 42 is partially lifted and separates from the outer peripheral surface of the photoreceptor 9. As a result, exhaust is performed, and pressure adjustment in the casing member 62 is automatically performed.
[0075]
A sixth embodiment of the present invention 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, but has the same structure as the process cartridge 3 according to each of the above-described embodiments in that it does not include the low oxygen gas supply device. The structure is different.
[0076]
In a printer 72 that 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 unit 73a that stores the low-oxygen gas, and a supply pipe 73b to which the low-oxygen gas is supplied. The low-oxygen gas supply device 73 is provided in the process cartridge 71 mounted in the apparatus main body 74. The charging device 10 is detachably connected to the inlet 19.
[0077]
According to the present embodiment, it is not necessary to replace the low oxygen gas supply device 73 integrally when the process cartridge 71 is replaced, and it is possible to replace the low oxygen gas supply device 73 separately from the process cartridge 71 if necessary. I can do it. This eliminates the need to match the life of the process cartridge 71 and the low-oxygen gas supply device 73, increases the degree of freedom in designing the process cartridge 71 and the low-oxygen gas supply device 73, and can reduce the cost. .
[0078]
【The invention's effect】
According to the charging device of the first aspect of the present invention, the low-oxygen gas is introduced into the casing member from the introduction port, so that the oxygen concentration in the casing member becomes low, and the generation of discharge products due to the discharge phenomenon is reduced. Further, 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 by the increase in the pressure. It is possible to prevent oxygen adhering to the outer peripheral surface from entering the casing member with the rotation of the image bearing member, and to further reduce the generation of discharge products due to the discharge phenomenon.
[0079]
According to the second aspect of the present invention, in the charging device according to the first aspect, a tip attached to a downstream edge of the casing member along a rotation direction of the image carrier and facing the image carrier. Since the section has a flexible downstream seal curved toward the downstream side in the rotation direction of the image carrier and slidably contacting the outer peripheral surface of the image carrier, low oxygen gas is introduced into the casing member. The pressure in the casing member at the time of the above is increased, and the pressing force of the upstream seal against the outer peripheral surface of the image carrier can be increased, whereby oxygen attached to the outer peripheral surface of the image carrier becomes It is possible to further prevent entry into the casing member due to rotation, and further reduce generation of discharge products due to a discharge phenomenon.
[0080]
According to the third aspect of the present invention, in the charging device according to the first or second aspect, the inlet is formed in a side surface of the casing member in a direction along an axis of the charging roller. In addition, the low oxygen gas introduced into the casing member flows quickly along the axial direction of the charging roller, and the upstream seal can be quickly pressed against the outer peripheral surface of the image carrier.
[0081]
According to the process cartridge of the fourth aspect of the present invention, since the charging device of the first aspect of the present invention includes the charging device of the first aspect, it is possible to reduce the generation of discharge products due to the discharge phenomenon.
[0082]
According to the fifth aspect of the present invention, in the process cartridge according to the fourth aspect, a low oxygen gas supply device is provided that is connected to the inlet and supplies a low oxygen gas from the inlet. Can be exchanged integrally with the process cartridge, and the handleability can be improved.
[0083]
According to the image forming apparatus of the present invention, since the process cartridge of the present invention is provided, it is possible to reduce the generation of discharge products at the time of discharging for charging the image carrier, and to generate the discharge products. It is possible to prevent a decrease in image quality due to the influence of an object.
[0084]
According to the image forming apparatus of the present invention, since the process cartridge according to the fourth aspect and the low-oxygen gas supply device connected to the introduction port are provided, a discharge for charging the image carrier is performed. In addition, since the generation of discharge products can be reduced to prevent deterioration of image quality due to the influence of discharge products, and since the low oxygen gas supply device is provided in the image forming device separately from the process cartridge, When the cartridge is replaced, the low oxygen gas supply device can be continuously used without being replaced integrally.
[0085]
According to an eighth aspect of the present invention, in the image forming apparatus according to the sixth or seventh aspect, a predetermined time elapses after the charging roller is rotated and the supply of the low oxygen gas from the low oxygen gas supply device is started. Since a control means for starting voltage application to the charging roller later is provided, when the voltage is applied to the charging roller, the inside of the casing member is filled with a low oxygen gas, so that generation of discharge products at the time of charging the image carrier is generated. Can be reliably reduced.
[0086]
According to the ninth aspect of the present invention, in the image forming apparatus according to the sixth or seventh aspect, the supply of the low oxygen gas from the low oxygen gas supply device after a lapse of a predetermined time after rotating the charging roller in a predetermined direction. The control means for starting the voltage application to the charging roller after a predetermined time has elapsed after the supply of the low oxygen gas is started, so that when the voltage is applied to the charging roller, the inside of the casing member is filled with the low oxygen gas. Therefore, it is possible to reliably reduce the generation of discharge products when the image carrier is charged, and to supply the low-oxygen gas after rotating the charging roller and generating an airflow around the charging roller. Thereby, the filling of the low oxygen gas into the casing member can be promptly performed by putting it on the generated airflow.
[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 illustrating a detached state of a process cartridge.
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 a further enlarged charging device.
FIG. 6 is a block diagram showing an electrical connection of a portion related to the supply of low oxygen gas in the printer.
FIG. 7 is a flowchart illustrating supply of a low oxygen gas.
FIG. 8 is a cross-sectional view illustrating a charging device according to a second embodiment of the present invention.
FIG. 9 is a cross-sectional view illustrating a charging device according to a third embodiment of the present invention.
FIG. 10 is a sectional view illustrating a charging device according to a fourth embodiment of the present invention.
FIG. 11 is a sectional view illustrating a charging device according to a fifth embodiment of the present invention.
FIG. 12 is a plan view illustrating a printer 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 Developing device
13 Low oxygen gas supply device
13c Supply port
15 Charging roller
16 Casing member
18 upstream seal
19 Introduction
31 Charging device
32 Inlet
41 Charging device
42 Downstream seal
51 Charging device
54 Inlet
61 Charging device
65 Inlet
71 Process cartridge
73 Low oxygen gas supply device
S2 to S6 control means

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 a rotation axis of the image carrier;
A casing member surrounding the charging roller,
The casing is attached to an edge of the casing member on the upstream side along the rotation direction of the image carrier, and a tip portion facing the image carrier side is curved toward the downstream side in the rotation direction of the image carrier to form the image. A flexible upstream seal slidably contacting the outer peripheral surface of the carrier,
An inlet formed in the casing member, and a low oxygen gas is introduced into the casing member,
A charging device having: The casing member is attached to a downstream edge of the image carrier along the rotation direction of the image carrier, and a front end portion facing the image carrier is curved toward the downstream side of the image carrier in the rotation direction of the image carrier. The charging device according to claim 1, further comprising a flexible downstream seal slidably contacting the outer peripheral surface of the carrier. The charging device according to claim 1, wherein the inlet is formed in a side surface of the casing member in a direction along an axis of the charging roller. An image carrier;
A charging device according to any one of claims 1 to 3,
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,
A process cartridge 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 inlet and supplying a low oxygen gas from the inlet. A process cartridge according to claim 5,
An optical writing device that forms an electrostatic latent image on the image carrier provided in the process cartridge;
A transfer device for transferring the toner image formed on the outer peripheral surface of the image carrier to a recording medium,
A fixing device for fixing the toner image transferred to the recording medium,
An image forming apparatus having: A 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;
A transfer device for transferring the toner image formed on the outer peripheral surface of the image carrier to a recording medium,
A fixing device for fixing the toner image transferred to the recording medium,
An image forming apparatus having: 8. The control device according to claim 6, further comprising a control unit configured to start 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 while the charging roller rotates. 9. Image forming device. After the lapse of a predetermined time after rotating the charging roller, the low-oxygen gas supply device supplies a low-oxygen gas, and after a lapse of a predetermined time after the supply of the low-oxygen gas is started, voltage is applied to the charging roller. The image forming apparatus according to claim 6, further comprising a control unit that starts the image forming apparatus.

Images