JP2004240119A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that controls the interior of a development device to desired environment by supplying control gas to a flow path and supplying the control gas into the interior of the development device by using a surface-layer air flow on a rotary roller disposed opposite the slit-like opening of a flow path forming member. <P>SOLUTION: The image forming apparatus includes a rotary member 70 which is disposed on the upstream side of a development area in the direction of the movement of a photoreceptor drum 40, located close to and opposite to a development sleeve 65 and the photoreceptor drum 40 so that its surface moves in the same direction as the movement of the surface of the photoreceptor drum 40; and a flow path forming part 72 in which the slit-like opening is formed in the axial direction of the rotary member 70 and the rotary member 70 faces the opening, and thus an inside space is defined as the flow path. The control gas 102 flows through the flow path 71. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copier, a facsimile, and a printer, and more particularly, to a latent image carrier that carries a latent image on a surface thereof, and a surface provided so as to face the surface of the latent image carrier. In a developing area where a developer carrying member carrying the developer is close to and opposed to the developer, the developer carried on the surface of the developer carrying member is supplied to the latent image formed on the latent image carrying member to supply the developer. The present invention relates to an image forming apparatus including a developing unit that visualizes a latent image.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a dry electrophotographic image forming apparatus such as a printer, a facsimile, a copying machine, and the like, various problems have occurred due to fluctuations in an environment in a developing device. As a problem, there is a change in triboelectric charging characteristics of the developer. It is known that this variation directly affects image quality.
For this reason, studies have been made to actively control the environment in the developing device and stabilize the triboelectric charging characteristics of the developer. For example, in the developing device of Patent Document 1, when a humidity sensor detects that the humidity of the developer in the developing device exceeds an upper limit within a certain range, a dry gas such as nitrogen is supplied from a dry gas supply source. It is supplied into the developing device. The moisture in the developing device is removed by the dry gas, and the dry gas is caught in the developer with stirring of the developer, thereby lowering the humidity of the developer. Further, in the developing device of Patent Document 2, excessive moisture in the device is removed by providing a moisture absorbing means covered with a moisture-permeable substance having fine pores in the developing device. The developing device of Patent Document 3 removes moisture from the developer by subjecting the developer to heat treatment under reduced pressure in the developing device.
Note that it is known that various problems are caused by the scattering of the developer from the periphery of the developing area which is the opening of the developing device. Various proposals have been made, such as Patent Literature 4, Patent Literature 5, and Patent Literature 6, for preventing scattering of the developer.
[0003]
[Patent Document 1]
JP-A-6-19293
[Patent Document 2]
JP-A-7-128967
[Patent Document 3]
JP 2001-109263 A
[Patent Document 4]
JP-A-5-66663
[Patent Document 5]
JP-A-10-3220
[Patent Document 6]
JP-A-63-159887
[0004]
[Problems to be solved by the invention]
In order to provide an image forming apparatus with high image quality, there is an increasing demand for actively controlling the environment in the developing device to stabilize the frictional charging characteristics of the developer. This is even more so in a color image forming apparatus that has been widely used in recent years.
In a charging method other than the frictional charging, for example, a charge injection method, a similar problem that the environment in the developing device is positively controlled to stabilize the charging characteristics of the developer may occur.
[0005]
The present invention has been made in view of the above background, and an object of the present invention is to provide an image forming apparatus capable of controlling the inside of a developing device to a desired environment.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention provides a latent image bearing member that carries a latent image on a surface, and a developer that is provided to face the surface of the latent image carrier and carries a developer on the surface. In the developing region where the developer carrier is close to and opposed to the developer, the developer carried on the surface of the developer carrier is supplied to the latent image formed on the latent image carrier to visualize the latent image. In the image forming apparatus having a developing unit, the developer carrying member is supported so as to be close to and opposed to the developer carrying member and the latent image carrying member on the upstream side of the developing region in the moving direction of the developer carrying member surface, A rotating member that rotates so that the surface moves in the same direction as the direction of movement of the surface at a portion facing the surface of the latent image carrier, and a slit-shaped opening formed in the axial direction of the rotating member, A flow path in which a rotating member faces the opening and the internal space forms a flow path And a formation member provided is characterized in that the circulating control gas flow path.
According to a second aspect of the present invention, there is provided a latent image bearing member that carries a latent image on a surface thereof, and a developer carrier that is provided to face the surface of the latent image carrier and carries a developer on the surface. An image provided with a developing means for supplying a developer carried on the surface of the developer carrier to the latent image formed on the latent image carrier in a developing region which is close to and opposed to the latent image carrier to visualize the latent image; A forming device configured to support the developer carrier and the latent image carrier in close proximity to the developer carrier and the latent image carrier on the downstream side of the developing region in the moving direction of the developer carrier surface; A rotating member that rotates so that the surface moves in a direction opposite to the direction of movement of the surface at a portion facing the rotating member; and a slit-shaped opening formed in the axial direction of the rotating member. A flow path forming member is provided in which the members face each other, and the internal space forms a flow path, It is characterized in that the circulating control gas into the flow path.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the latent image formed on the latent image carrier is supplied with a developer carried on the surface of the developer carrier to produce the latent image. An end side member of a developing device having a developing means for developing an image, and a predetermined minute gap between the latent image carrier and the upstream and downstream sides of the rotating member in the moving direction of the surface of the latent image carrier The end of the opposing member is in close contact with the opening, or is integrally formed, and at least one ridge is provided such that the end side member is convex toward the side facing the latent image carrier, The ridge is provided with a groove that enters the end of the latent image carrier.
According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, means is provided for moving the rotating member in a direction in which a distance from the latent image carrier changes.
According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect, the surface of the rotating member is provided with a flock, and the flock contacts the flow path forming member. It is characterized by the following.
According to a sixth aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, or fifth aspect, a pressure sensor for detecting a pressure inside the developing device, and a pressure reducing capability inside the developing device is variable. A pressure reducing means, wherein the number of revolutions of the developer carrying member is made variable, and the pressure reducing ability is controlled so that the pressure inside the developing device becomes constant during operation.
According to a seventh aspect of the present invention, in the image forming apparatus of the first, second, third, fourth, or fifth aspect, a pressure sensor for detecting a pressure inside the developing device is provided, and the number of rotations of the developer carrier is controlled. The rotation speed of the rotating member is controlled so that the pressure inside the developing device becomes constant during operation.
According to the first to seventh aspects of the present invention, the rotary member has a rotating member supported so as to be closely opposed to the developer carrying member and the latent image carrying member, and a slit-shaped opening formed in the axial direction of the rotating member. And a flow path forming member in which a rotating member faces the opening and whose internal space forms a flow path, is provided in the developing device. Then, by supplying the control gas to be supplied to the flow path into the developing device by the surface airflow accompanying the rotation of the rotating member, the inside of the developing device can be controlled to a desired environment.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a color printer which is an image forming apparatus of a tandem type intermediate transfer system will be described.
FIG. 1 is a schematic configuration diagram of a color printer to which the present invention can be applied. This color printer comprises a copying apparatus main body 100, a paper feed table 200 on which the copying machine main body 100 is mounted, a scanner 300 mounted on the copying apparatus main body 100, and an automatic document feeder (ADF) 400 mounted thereon. Is done. An intermediate transfer belt 10 as an endless belt-shaped intermediate transfer member is provided at the center of the copying apparatus main body 100.
[0008]
The intermediate transfer belt 10 is wound around three supporting rotary rollers 14, 15, 16 as shown in FIG. 1 to be rotatable clockwise in the figure. In the illustrated example, an intermediate transfer body cleaning device 17 that removes residual toner remaining on the intermediate transfer belt 10 after image transfer is provided to the left of the second support rotation roller 15. On the intermediate transfer belt 10 stretched between the first support rotation roller 14 and the second support rotation roller 15, four image forming units of yellow, cyan, magenta, and black are provided along the conveyance direction. The tandem image forming unit 20 is configured by arranging 18Y, C, M, and B side by side. The order of these four colors is an example, and the present invention is not limited to this.
The intermediate transfer belt 10 is configured by laminating a base layer, an elastic layer, and a coat layer in this order. The base layer is made of a material that does not easily stretch, such as a fluororesin or canvas. The elastic layer is made of, for example, fluorine rubber or acrylonitrile-butadiene copolymer rubber. The coat layer is formed by coating the surface of the elastic layer with a material having good smoothness, such as a fluororesin.
[0009]
An exposure device 21 is provided on the tandem image forming section 20, as shown in FIG. On the other hand, on the opposite side of the intermediate transfer belt 10 from the tandem image forming unit 20, a secondary transfer device 22 as a secondary transfer unit is provided. A fixing device 25 for fixing a transferred image on a sheet is provided beside the secondary transfer device 22. The fixing device 25 is configured by pressing a pressing rotary roller 27 against a fixing rotary roller 26 as a fixing member.
[0010]
The secondary transfer device 22 also has a sheet conveying function for conveying the sheet after the image transfer to the fixing device 25. Of course, a transfer rotating roller or a non-contact charger may be disposed as the secondary transfer device 22, and in such a case, it is difficult to additionally provide the sheet conveying function. In the illustrated example, a sheet reversing device 28 that reverses the sheet so as to record an image on both sides of the sheet is provided below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming unit 20 described above. .
[0011]
FIG. 2 is a schematic explanatory view of the tandem image forming unit 20 in the printer of the present embodiment, which is partially enlarged around the developing device 60. In the tandem image forming section 20, as shown in FIG. 2, an image forming means 18 as an individual toner image forming means includes a developing device around a photosensitive drum 40 having a diameter of 60 mm as a drum-shaped latent image carrier. 60, a charging device 61, a primary transfer device (not shown), a photoconductor cleaning device, a static elimination device, and the like. The photosensitive drum 40 has a drum shape in which a photosensitive layer is formed by applying a photosensitive organic photosensitive material to a base tube such as aluminum, but may have an endless belt shape. Although not shown, at least the photosensitive drum 40 is provided, and a process cartridge is formed by all or a part of the portion forming the image forming unit 18, and is detachably mounted on the copier main body 100 in a lump to improve maintainability. You may make it improve.
[0012]
The developing device 60 uses a two-component developer composed of a magnetic carrier and a non-magnetic toner. As shown in FIG. 3, a developing sleeve 65 having a diameter of 30 mm as a developer carrier is provided facing the photosensitive drum 40 through an opening of the developing case 80, and a magnet (not shown) is provided in the developing sleeve 65. Provide fixed. In addition, a doctor blade 66 is provided with the tip approaching the developing sleeve 65. The agitating section 67 for transporting the two-component developer while adhering it to the developing sleeve 65 is provided with two screws 68, and is separated by a partition plate 69 except for both ends. The two-component developer in the stirring section 67 is transported and circulated while being stirred by the two screws 68, and is supplied to the developing sleeve 65. The developer supplied to the developing sleeve 65 is pumped up and held by a magnet (not shown), and forms a magnetic brush on the developing sleeve 65. The magnetic brush is cut into appropriate amounts by the doctor blade 66 as the developing sleeve 65 rotates. The cut-off developer is returned to the stirring section 67. On the other hand, the toner in the developer on the developing sleeve 65 is transferred to the photosensitive drum 40 by a developing bias voltage applied to the developing sleeve 65, and the electrostatic latent image on the photosensitive drum 40 is visualized. After the visualization, the developer remaining on the developing sleeve 65 returns from the developing sleeve 65 to the agitating section 67 where there is no magnetic force of a magnet (not shown).
[0013]
As shown in FIG. 2, the photosensitive drum 40 and the developing sleeve 65 are located on the upstream side in the moving direction of the surface of the developing sleeve 65 (hereinafter referred to as the upper portion of the developing nip). And a downstream side (hereinafter, referred to as a developing nip lower space), which is opposed to the developing sleeve 65 and the photosensitive drum 40, respectively, and is rotatably supported by a motor (not shown). And two rotating rollers 70a and 70b about 6 mm from each other. The rotating roller 70a rotates so that the surface moves in the same direction as the direction of movement of the photosensitive drum 40 at the opposing portion of the photosensitive drum 40, and the rotating roller 70b rotates at the opposing portion of the photosensitive drum 40. The rotation is performed so that the surface moves in a direction opposite to the direction of movement of the body drum 40. Here, the peripheral speed of the rotating roller 70 is set to be substantially the same as the peripheral speed of the photoconductor, but the peripheral speed of the rotating roller can be varied as described later. It has a slit-shaped opening formed in the axial direction of each of the two rotating rollers 70a, b, and the rotating rollers 70a, 70b face the opening, and the internal spaces form flow paths 71a, 71b, respectively. The flow path forming members 72a and 72b are provided. Further, in order to restrict the photoconductor surface layer airflow 101 as shown by the broken arrow in FIG. 2 from entering the upper space of the developing nip, and to prevent the gas containing the scattered toner from flowing out of the developing device from the lower space of the developing nip. In order to suppress the above, gap opposing members 73a and 73b that respectively form predetermined gaps G1 and G2 with the photosensitive drum 40 are provided. The two gap opposing members 73a and 73b are configured to be integral with or contact with the flow path forming members 72a and 72b, respectively.
[0014]
Control gases 102 and 103 prepared as shown in FIG. 3 are passed through the two flow paths 71a and 71b, respectively. Further, of the two portions where the slit opening of the flow path forming member and the two rotating rollers 70a and 70b are close to each other, a developing nip upper space and a developing nip Scrapers 74a and 74b are provided to prevent the scattered toner from entering the flow paths 71a and 71b from the lower space and the unnecessary outflow of the control gas. Since the two flow paths 71a and 71b have a longer distance in the axial direction of the flow path than the cross-sectional area of the flow path, the pressure loss is large. Therefore, in general, a pump or the like that can achieve a large static pressure with a small flow rate is used for supplying the control gas. In the present embodiment, a diaphragm pump is used. In this embodiment, since the flow path cross-sectional area is small, it is easy to form the flow path with a single member, and it is easy to obtain a flow path with good airtightness. The control gases 102 and 103 supplied from the respective flow paths 71a and 71b flow out to the space around the developing nip as a surface airflow due to the rotation of the rotating rollers 70a and 70b facing the respective flow paths. Since the flow rate is very small, the pressure inside the two flow paths 71a and 71b is high, and a stable surface airflow is formed in the axial direction. The surface airflow formed by the rotating roller 70a prevents the surface airflow 101 of the photosensitive drum 40 flowing from the photosensitive drum 40 from flowing out to the developing nip. With this function, the amount of outside air flowing into the developing device can be reduced, and the environment in the developing device can be stably maintained. Further, the surface airflow formed by the rotating roller 70b prevents the control gas including the scattered toner downstream of the developing nip from flowing out of the developing device as the surface airflow of the photosensitive drum 40.
The control gases 102 and 103 are gases controlled to stabilize the triboelectric charging characteristics of the developer, for example, gases in which at least one of temperature and humidity is controlled, and adjusting means such as a tank. Sent from
[0015]
The developing device 60 usually has a closed structure because the developer circulates therein and the toner having a low charge amount floats. Therefore, in order to prevent the control gas 103 from flowing out of the gap G2 between the photosensitive drum 40 and the gap opposing member 73b, a pressure reducing means 75 in the developing device, which will be described later, is provided via a filter 76.
[0016]
FIGS. 3 and 4 show a developing device according to the present embodiment in which two gap opposing members 73a and 73b are brought into close contact with an end formed by a sleeve upper cover 82a or a developing lower case 81b. FIG. A rib 83, which is a ridge, is provided at an end portion of the developing device opposite to the photoreceptor flange portion 84, and is inserted into a groove 89 provided in the photoreceptor flange portion 84 in a comb shape. By providing the ribs 83 on the stationary developing device side, it is possible to reduce the size when combined, rather than providing the ribs 83 on the photosensitive drum 40 side. By providing the ribs 83, the control gases 102 and 103 flowing out of the two flow paths 70a and 70b into the space around the developing nip are blown out from both ends in the axial direction of the space around the developing nip toward the outside of the developing device. To prevent spills. Further, since the amount of outside air mixed in the gas flowing into the developing device can be reduced, the environment in the developing device is stabilized.
The gap between the rib 83 and the groove 89 provided in the photoreceptor flange 84 is set to be as small as possible. This increases the pressure loss when the gap between the rib 83 and the groove 89 provided in the photoreceptor flange 84 is regarded as a flow path, thereby preventing the control gas 102 and the control gas 103 from leaking. In addition, increasing the number of ribs, increasing the length of the flow path, and changing the direction of the flow of the control gas are also effective as means for preventing leakage of the control gas. According to these means, the configuration is simple, and the unit can be easily attached and detached. During operation, in addition to the generation of the surface airflow in the same direction due to the rotation of the photosensitive drum 40, the formation of the rib 83 restricts the outflow of the control gas flowing into the space around the developing nip to the outside. As a result, the space around the development nip is substantially sealed, so that the control gases 102 and 103 supplied from the two flow paths 71a and 71b are supplied to the inside of the development device 60 by balance with the pressure inside the development device. Flows into Further, since the space around the developing nip is filled with the control gas, the environment until the toner is developed by the electric field can be controlled. These functions make it possible to stabilize an image. Further, since the ratio of the control gas is high in the developing device, the circulation system is easily formed by collecting the gas.
Further, as shown in FIG. 5, a contact-type seal member 85 may be provided on the rib 83 side of the developing device 60. With a simple configuration in which the seal member 85 is provided on the side surface of the rib 83, the gap between the developing sleeve 65 and the photosensitive drum 40 can be maintained at the same time, and the compressive deformation of the seal member 85 can be suppressed to maintain the sealing performance. It is possible, and an increase in the sliding load can be suppressed.
[0017]
Next, adjustment of the pressure in the developing device 60 will be described. In the present embodiment, in addition to the above-described depressurizing means 75 shown in FIG. 2, a means for supplying a control gas into the developing device 60 by means of a change in the number of rotations of two rotating rollers 70 a and 70 b, The internal pressure of the developing device is adjusted by means for supplying pressure by the control gases 102 and 103 supplied from the passages 70a and 70b, respectively. Then, the pressure is detected by a pressure sensor that detects a pressure difference from the outside during the operation of the developing device as shown in FIG. 2, and the above-mentioned adjusting means is controlled so as to be a predetermined pressure. Even in an image forming apparatus in which the number of revolutions of the developing sleeve 65 is variably set, it is possible to adjust the pressure in the developing apparatus to prevent the pressure in the space around the developing nip from increasing, and to reduce the toner caused by the pressure fluctuation. Scattering can be prevented.
[0018]
As the pressure reducing means 75, for example, a suction pump can be used. In addition, the pressure can be adjusted by utilizing a negative pressure or the like obtained by opening into another airflow. By providing the pressure reducing means 75, it becomes easy for the control gas 103 to flow into the developing device from the space below the developing nip. The control gas 102 supplied from the upper space of the developing nip is hardly affected by the pressure reduction in the developing device because it is blocked by the developing nip.
Further, by providing the pressure reducing means 75 in the internal space of the developing device 60 having a relatively large capacity, it is possible to increase the pressure adjustment range, and accordingly, the permissible range of the peripheral speed of the developing sleeve 65 and the like is increased. It is also possible.
[0019]
When adjusting the pressure in the developing device by changing the rotation speed of the rotating roller 70, for example, it is effective to reduce the peripheral speed of the rotating roller 70 in order to suppress the internal pressure in the developing device. On the other hand, since the peripheral speed of the rotating roller 70 has both the function of sending the control gas as the surface airflow of the rotating roller and the effect of preventing toner scattering, the peripheral speed of the rotating roller 70 has an appropriate range that can be set. Since it is easy to finely adjust the number of rotations of the rotating roller 70, it is possible to balance toner scattering and a control gas sending function while adjusting the pressure, thereby contributing to the operation stability of the apparatus. Further, by using the rotating roller 70 for feeding the control gas also as a driving unit for pressure adjustment, the size of the apparatus can be reduced. In addition, the rotation speed of the rotation roller 70 can be finely adjusted, so that operation stability can be improved. In addition, the mechanism for controlling the number of rotations of the rotating roller can reduce the size of the apparatus as compared with providing a pump unit or the like.
[0020]
The pressure supply means is an auxiliary means for adjusting the pressure. If the decompression inside the developing device 60 and the supply of the control gases 102 and 103 to the two flow paths 71a and 71b are performed by a single pump, the control gas constitutes a circulating system, so that the device configuration is simply simplified. Instead, it is only necessary to newly adjust and supply a small amount of control gas corresponding to the amount of leak, so that the choice of types of control gas can be expanded.
In addition to the image forming apparatus in which the peripheral speed of the developing sleeve 65 is variably set depending on the image forming conditions even when the peripheral speed of the photosensitive drum 40 is constant, the peripheral speed of the plurality of photosensitive drums 40 and the developing sleeve The present invention is also applicable to an image forming apparatus in which a peripheral speed of 65 is set.
[0021]
In the standby state, the amount of the control gas flowing out of the space around the developing nip to the outside is small, and thus the supply amount of the control gas in this state is an amount that compensates for the outflow.
Further, the present invention can be realized without changing the configuration on the developing device side even in a counter developing system in which the photosensitive drum 40 rotates in the reverse direction in the figure.
[0022]
8, 9, and 10 are enlarged explanatory views of the rotating roller 70. The peripheral surface of the rotating roller 70 is processed by sandblasting so as to make the surface unevenness large as shown in FIG. By performing this processing, it is possible to form a thick surface airflow due to the rotation of the rotating roller 70. As a result, the control gases 102 and 103 can be smoothly fed into the developing device by the surface airflow caused by the rotation of the two rotating rollers 70a and 70b. Further, the effect of separating the surface airflow 101 of the photosensitive drum 40 is increased. As a method of processing the peripheral surface of the rotating roller, any method may be used as long as it can make the surface unevenness large. For example, etching such as the surface shape shown in FIG. 8 and cutting and rolling as shown in FIG. Processing methods can be used. Although the cost is slightly higher than that of the processing method, electrostatic flocking may be applied to the peripheral surface of the rotating roller as shown in FIG. A large amount of control gas can be included in the flocking, and the action of separating the surface airflow 101 of the photoconductor drum 40 can be enhanced to drive the flow. Furthermore, since the flocking portion is flexible, the flow path forming member and the flocking portion can be kept in contact with each other as shown in FIG. 10, so that unnecessary leakage from the gap can be prevented, and the two flow paths 71a, The use efficiency of the control gases 102 and 103 supplied from b can be increased. The material of the rotating roller 70 is made of metal, resin, or the like set to the same potential as the developing bias.
[0023]
When making a copy using the above-described color electrophotographic apparatus, an original is set on the original table 30 of the automatic original transport apparatus 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed.
Then, when a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is conveyed and moved onto the contact glass 32, and then the document is set on the other contact glass 32. At this time, the scanner 300 is immediately driven to travel on the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface to the second traveling body 34, is reflected by the mirror of the second traveling body 34, and passes through the imaging lens 35. The original is read by the reading sensor 36 and read.
[0024]
Then, the photoconductor drums 40Y, C, M, and B are rotated by the individual image forming units 18Y, C, M, and B, and the charging devices 60Y, C are firstly rotated with the rotation of the photoconductor drums 40Y, C, M, and B. , M, and B uniformly charge the surfaces of the photosensitive drums 40Y, C, M, and B, and then use a laser, an LED, or the like from the above-described exposure devices 21Y, C, M, and B according to the contents read by the scanner 300. By irradiating the writing light L, an electrostatic latent image is formed on the photosensitive drums 40Y, 40C, 40M, 40B.
Thereafter, toner is adhered by the developing devices 60Y, C, M, and B to visualize the electrostatic latent image, so that yellow, cyan, magenta, and black are respectively formed on the photosensitive drums 40Y, C, M, and B. Is formed. One of the support rotation rollers 14, 15, 16 is driven to rotate by a drive motor (not shown), the other two support rotation rollers are driven to rotate, the intermediate transfer belt 10 is rotated and conveyed, and the visible image is primarily The image is sequentially transferred onto the intermediate transfer belt 10 by a transfer device. Thereby, a composite color image is formed on the intermediate transfer belt 10. The surfaces of the photoconductor drums 40Y, 40C, 40M, 40B after image transfer are cleaned by removing residual toner with photoconductor cleaning devices 63Y, 63C, 63M, and 63B to be described later. To prepare for the next image formation.
[0025]
On the other hand, when a start switch (not shown) is pressed, one of the paper feed rotation rollers 42 of the paper feed table 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in the paper bank 43 in multiple stages. The sheets are separated one by one by a roller 45 and put into a sheet feeding path 46, conveyed by a conveying rotation roller 47, guided to a sheet feeding path 48 in the copying machine main body 100, and stopped against a registration rotation roller 49. Alternatively, the sheets on the manual feed tray 51 are fed out by rotating the paper feed rotation roller 50, separated one by one by the separation rotation roller 52, put into the manual paper feed path 53, and similarly stopped against the registration rotation roller 49. Then, the registration rotating roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, and the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and is transferred by the secondary transfer device 22. To record a color image on the sheet. Here, the resist rotating roller 49 is generally used in a grounded state, but it is also possible to apply a bias for removing paper dust from the sheet.
[0026]
It is to be noted that a method of directly transferring from the photosensitive drum 40 to transfer paper without using a transfer belt may be adopted.
Further, in the present embodiment, a developing device is individually provided for each of the four photoconductor drums 40 arranged in a row, a single-color toner image is formed on each of the photoconductor drums 40, and the single-color toner images are sequentially transferred to a sheet to form a composite color image. Although the present invention is applied to a so-called tandem type color printer which forms the above, the printer to which the present invention can be applied is not limited to this type of printer. An image forming apparatus that includes at least a developer carrier and a latent image carrier, sets a development gap to a predetermined value, and drives at least one of the developer carrier and the latent image carrier to perform development. Is applicable.
[0027]
[Modification 1]
FIG. 6 is a schematic configuration diagram around a developing device 60 according to a modification. The developing device 60 supplies the control gas 102 only from the upper space of the developing nip for the purpose of filling the inside with the control gas. The control gas 102 flows into the developing device 60 through the developing nip, and is gradually filled with air in the developing device 60. Then, the surplus flows out of the end of the developing sleeve 65 to the outside. Since the amount of control gas flowing into the developing device 60 per unit time through the development nip is very small, this outflow does not promote toner scattering. Therefore, in the present modification, the decompression means 75 is not required, and the apparatus can be downsized.
By flowing a control gas into the space facing the photoconductor drum 40 upstream of the development nip space in the surface movement direction of the photoconductor drum 40 and sending the control gas into the development device, the environment in the development device is changed to a desired environment. Although the adjustment can be performed, the following effects can be obtained since the control gas supply region is limited as compared with the method.
First, the amount of control gas to be supplied can be small. As a result, the control gas supply means can be made smaller than in the above method. Further, it is possible to broaden the options of the control gas, for example, use of an inert gas.
Second, the cross-sectional area of the flow path can be reduced. As a result, it is easy to configure the flow path with a single member, and a flow path with good airtightness can be obtained.
Third, it is possible to supply control gas with high pressure. As a result, the control gas flows into the space facing the photoconductor drum 40 upstream of the development nip space in the surface movement direction of the photoconductor drum 40, and the control gas is sent into the development device. As compared with the method of adjusting to the environment described above, the replacement of the gas in the developing device can be accelerated.
When a control gas is supplied to the charging unit in order to prevent discharge products such as ozone and NOx generated by the discharging of the charging unit from adversely affecting the photosensitive drum 40 and impairing the durability of the apparatus. However, a control gas shared with the charging unit can be supplied. For example, when an inert gas is used as a control gas to be supplied to the charging unit, the inert gas can also be used as a control gas to be supplied to the developing device. Options can be increased.
Also in this modified example, the same effect as in the above-described embodiment can be obtained by providing the rib 83 on the side surface of the end portion of the developing device and making the groove 89 and the rib 83 provided in the photoreceptor flange 84 enter the comb teeth shape. Obtainable.
[0028]
[Modification 2]
FIG. 7 is a schematic configuration diagram around a developing device 60 according to another modification. The developing device 60 supplies the control gas 103 only from the space below the developing nip for the purpose of stabilizing the environment inside the developing device by filling the inside with the control gas and suppressing toner scattering.
In the case of the present modification, the amount of control gas passing through the rotating roller 70b is larger than in the case of the first modification, so that the pressure reducing means 75 is provided.
The following effects are obtained by supplying the control gas 103 only from the lower part of the developing nip.
First, it is possible to suppress the gas in the lower region of the development nip from flowing out to the outside due to the surface airflow of the rotating roller 70b. As a result, in addition to stabilizing the environment in the developing device, toner scattering can be suppressed.
Second, compared to a method in which the control gas 102 is supplied only from the upper space of the development nip, the control gas 103 having a high pressure can be supplied because there are fewer obstacles such as the development nip. As a result, the replacement of the gas in the developing device can be accelerated as compared with the method of supplying the control gas 102 from the upper portion of the developing nip.
Further, by providing the decompression means 75 in the developing device 60, the gas suction action in the space below the developing nip can be increased, and the replacement of the gas in the developing device 60 can be further expedited.
Also in this modified example, the same effect as in the above-described embodiment can be obtained by providing the rib 83 on the side surface of the end portion of the developing device and making the groove 89 and the rib 83 provided in the photoreceptor flange 84 enter the comb-like shape. Obtainable.
[Modification 3]
11 and 12 are schematic illustrations of two rotatable rotatable rollers 70a and 70b according to another modification. The drive means for the two rotating rollers 70a and 70b is shared with a gear 86 for driving the developing sleeve 65 via an idler gear 87 having a fixed center of rotation. However, the drive means for the two rotating rollers 70a and 70b can be independently driven or shared with a gear for driving the photosensitive drum 40.
The two rotating rollers 70a and 70b are supported by swing arms 88a and 88b as supporting means, respectively. The swing arms 88a and 88b have a coaxial portion (not shown) so as to be located coaxially with the rotation shaft of the idler gear 87, whereby the two rotation rollers 70a and 70b can swing around the swing shaft portion. It has become. The two rotating rollers 70a and 70b are provided with moving means (not shown). For example, a biasing means using a spring can be used. The rotating roller is provided with a means for maintaining a predetermined gap with the photosensitive drum 40 during operation, and for positioning the rotating roller so as to be substantially in contact with the photosensitive drum 40 during standby.
During the image forming operation, as shown in FIG. 12, with the rotation of the developing sleeve 65, the two rotating rollers 70a and 70b rotate while maintaining a predetermined gap with the flow path forming members 71a and 71b, respectively. The surface airflow from the rotating rollers 70a and 70b is supplied into the developing device 60. On the other hand, when the operation is completed, the two rotating rollers 70a and 70b come into contact with the surface of the photosensitive drum 40 by the urging means, and a gap between the two rotating rollers 70a and 70b and the photosensitive drum 40 causing a leak is generated. Eliminate the gap. As a result, it is possible to prevent the control gas from flowing out of the gap portion during standby and prevent the outside air from being mixed into the developing device, and it is possible to maintain the environment in the developing device 60 for a long time. Further, since the amount of the control gas component in the developing device 60 is high, a circulation system can be easily configured. The gap between the flow path forming member 72 and the rotating roller 70 may be configured to be reduced.
[0029]
【The invention's effect】
According to the invention of claim 1, the rotating member has a slit-shaped opening formed in the axial direction of the rotating member, which is supported so as to be close to and opposed to the developer carrier and the latent image carrier, A flow path forming member in which a rotating member faces the opening and whose internal space forms a flow path is provided in the developing device. Since the control gas to be supplied to the flow path is supplied into the developing device as a surface airflow of the rotating member, the inside of the developing device can be controlled to a desired environment. As a result, it is possible to stabilize the triboelectric charging characteristics and the like, which are factors that are unstable with respect to environmental fluctuations, and to provide a high quality image forming apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a printer according to an embodiment.
FIG. 2 is a schematic configuration diagram of a developing device in the printer of the embodiment.
FIG. 3 is a schematic perspective view of a developing device according to the embodiment.
FIG. 4 is an explanatory diagram showing a configuration for preventing a control gas from flowing out from a side surface of an end of a developing sleeve according to the embodiment.
FIG. 5 is an explanatory view showing a configuration for preventing a control gas from flowing out from a side surface of an end of a developing sleeve according to another embodiment.
FIG. 6 is a schematic configuration diagram of a developing device according to another embodiment.
FIG. 7 is a schematic configuration diagram of a developing device according to another embodiment.
FIG. 8 is an explanatory diagram of a rotating roller according to the embodiment.
FIG. 9 is an explanatory diagram of a rotating roller according to another embodiment.
FIG. 10 is an explanatory diagram showing a configuration of a rotating roller and a flow path forming member according to another embodiment.
FIG. 11 is an explanatory view showing an example of a drive mechanism of a rotatable rotary roller according to another embodiment.
FIG. 12 is an explanatory view showing an example of a drive mechanism of a rotatable rotary roller according to another embodiment.
[Explanation of symbols]
40 Photoconductor drum
60 Developing device
65 Developing sleeve
70a, 70b rotating roller
71a, 71b channel
72a, 72b flow path forming member
73a, 73b Gap facing member
75 Decompression means
76 Filter
80 Developing case
81a Developing upper case
81b Developing lower case
82a Sleeve upper cover
83 rib
84 Photoreceptor flange
85 Sealing member
86 gear
87 idler gear
88a, 88b swing arm
101 Photoreceptor surface airflow
102 Control gas
103 Control gas

Claims (7)

A latent image bearing member that carries a latent image on the surface, and a developing region in which a developer carrier that is provided so as to face the surface of the latent image carrier and carries a developer on the surface is in close proximity to the surface, An image forming apparatus including a developing unit that supplies a developer carried on the surface of the developer carrier to the latent image formed on the latent image carrier to visualize the latent image,
On the upstream side of the developing area in the direction of movement of the surface of the developer carrier, the developer carrier and the latent image carrier are supported so as to be close to and opposed to each other, and a portion facing the surface of the latent image carrier A rotating member that rotates so that the surface moves in the same direction as the direction of movement of the surface,
A flow path forming member having a slit-shaped opening formed in the axial direction of the rotating member, the rotating member facing the opening, and an internal space forming a flow path,
An image forming apparatus, wherein a control gas is passed through the flow path. A latent image bearing member that carries a latent image on the surface, and a developing region in which a developer carrier that is provided so as to face the surface of the latent image carrier and carries a developer on the surface is in close proximity to the surface, An image forming apparatus including a developing unit that supplies a developer carried on the surface of the developer carrier to the latent image formed on the latent image carrier to visualize the latent image,
On the downstream side of the developing region in the moving direction of the surface of the developer carrier, the developer carrier and the latent image carrier are supported so as to be close to and opposed to each other, and a portion facing the surface of the latent image carrier A rotating member that rotates so that the surface moves in a direction opposite to the direction of movement of the surface,
A flow path forming member having a slit-shaped opening formed in the axial direction of the rotating member, the rotating member facing the opening, and an internal space forming a flow path,
An image forming apparatus, wherein a control gas is passed through the flow path. The image forming apparatus according to claim 1, wherein
An end side member of a developing device having a developing unit for supplying a developer carried on the surface of the developer carrier to the latent image formed on the latent image carrier to visualize the latent image; At the upstream and downstream sides of the rotating member in the moving direction of the surface of the latent image carrier, the latent image carrier is brought into close contact with the end of the facing member with a predetermined minute gap, or is integrally formed. Provided at least one ridge body such that the end side member is convex toward the side facing the latent image carrier,
An image forming apparatus comprising: a groove in which the ridge member enters an end of the latent image carrier. The image forming apparatus according to claim 3,
An image forming apparatus comprising: means for moving the rotating member in a direction in which a distance from the latent image carrier changes. The image forming apparatus according to claim 1, 2, 3, or 4,
An image forming apparatus, comprising: flocking on the surface of the rotating member, and wherein the flocking is in contact with the flow path forming member. The image forming apparatus according to claim 1, 2, 3, 4, or 5,
A pressure sensor for detecting the pressure inside the developing device,
A pressure reducing unit having a variable pressure reducing capability inside the developing device;
The rotation speed of the developer carrier is configured to be variable,
An image forming apparatus, wherein the pressure reducing capability is controlled so that the pressure inside the developing device is kept constant during operation. The image forming apparatus according to claim 1, 2, 3, 4, or 5,
A pressure sensor for detecting a pressure inside the developing device,
The rotation speed of the developer carrier is configured to be variable,
An image forming apparatus, wherein the number of rotations of the rotating member is controlled so that the pressure inside the developing device becomes constant during operation.

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