JP2004012522A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device preventing the unintended leakage of developer at another part by allowing the leakage of the developer at a specified part. <P>SOLUTION: The developing device 104 is provided with a housing 9 in which the developer is stored, an aperture 35 which is formed on the housing 9 and from which the developer is leaked, and a storage part 37 in which the developer leaked from the aperture 35 is stored. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a developing device provided in an image forming apparatus such as a copying machine, a facsimile, a printer, and the like, and relates to a developing device in which leakage of developer is improved.
[0002]
[Prior art]
Developing devices used in image forming apparatuses such as copiers, printers, and facsimile machines contain a large amount of developer therein, and use the developer to develop an image carrier such as a photoconductor. Has become. As the developer, a two-component developer having a toner and a carrier is well known. In a developing device using a two-component developer, the developer is stirred and mixed by a screw, a paddle or the like in a toner replenishing section, and then supplied to a developer carrier such as a developing roller. The developer carried on the developer carrier is transported to a position facing the image carrier, and the toner in the developer flies to the image carrier to perform development. The developer that has consumed the toner during the development is stirred and mixed again with the toner in the toner replenishing section to replenish the toner, supplied again to the developer carrier, and subjected to development.
[0003]
As described above, in the developing device in which the developer circulates repeatedly, since the developer is composed of fine particles, the developer intrudes into the fitting portions and the contact portions of the components constituting the developing device, and eventually. Is liable to cause a problem of developer leakage, that is, leakage outside the developing device. For this reason, a seal member such as a foamable elastic body or a filler is generally provided in a gap between the fitting portion and the contact portion in the developing device for the purpose of preventing leakage of the developer. ing.
[0004]
FIG. 5 shows a conventional example of a seal member. The developing device 4 accommodates a two-component developer having a toner and a carrier in a housing 109, and has an agent carrying portion 114 and an agent accommodating portion 115. The agent carrier 114 is disposed opposite to the photoconductor 1, which is a photoconductor drum as an image carrier, and performs development by supplying toner in a developer to a latent image formed on the photoconductor 1. And a developing doctor 118 as a doctor blade that is disposed to face the developing roller 117 and controls the amount of developer supplied to the photoconductor 1.
[0005]
The developer container 115 contains most of the developer and has a function of stirring the developer, and has a first stirring unit 119 and a second stirring unit 120. The first agitating member 121 provided in the first agitating section 119 and the second agitating member 122 provided in the second agitating section 120 direct the developer in different directions from each other in the first agitating section 119 and the second agitating section. It is stirred while being conveyed and circulated in the section 120.
[0006]
Then, the developer conveyed through the first stirring section 119 by the first stirring member 121 is attracted to the developing roller 117 by the magnetic force of a fixed magnetic pole (not shown) provided inside the developing roller 117, and the developer is transferred onto the surface of the developing roller 117. And pumped up. The developer on the surface of the developing roller 117 is regulated by the developing doctor 118, so that the amount of the developer after passing through the developing doctor 118 is kept constant and the developer is triboelectrically charged.
[0007]
Thereafter, by further rotation of the developing roller 117, the developer on the surface of the developing roller 117 is transported to a position facing the photoconductor 1, and when approaching the photoconductor 1, the developer is exposed to an electrostatic electric field on the surface of the photoconductor 1. Accordingly, the toner in the developer flies over the surface of the photoconductor 1 to perform the development. After the development, the developer returns to the developer container 115, is stirred and circulated by the first stirring member 121 and the second stirring member 122, is supplied with the toner, and is again subjected to the development.
[0008]
As described above, the developer is transported in the developing device 4. In this process, the developing device 4 serves as a seal member and a photosensitive roller 117 so that the developer does not leak out of the developing device 4. An entrance seal 131 for preventing toner scattering is provided between the body and the body 1. Further, the developing device 4 is provided with a foam as a sealing member at a fitting portion between the developing doctor 118 and the housing 109 so that the developer regulated by the developing doctor 118 does not rush and leak out of the developing device 4. The elastic member seal member 132 is interposed therebetween.
[0009]
Although specific examples of the seal member have been described above, with respect to the prevention of developer leakage in the developing device, for example, JP-A-2000-75656, JP-A-2000-131940, JP-A-2000-181222, and JP-A-5-182222. As described in JP-A-40402, JP-A-9-6212, JP-A-11-102119, etc., in order to prevent leakage of the developer from both ends of the developing roller, Proposals have been made to provide a seal member, or to improve the configuration of the seal member around the developing doctor to prevent the developer from being exposed, as described in Japanese Patent Application Laid-Open No. 2000-075657. Have been.
[0010]
[Problems to be solved by the invention]
However, in recent years, as the speed of the image forming apparatus has been increased and the particle size of the developer has been reduced along with the enhancement of image quality, depending on the seal member provided in the developing apparatus as shown in the above-described related art, the developer It has become difficult to completely prevent the leakage. In particular, with reference to the above-described specific example, in the vicinity of the developing doctor 118, most of the developer pumped up by the developing roller 117 is blocked, and the pressure from the developer continuously pumped one after another causes the dam to be stopped. The supplied developer moves along the developing doctor 118 in a direction away from the developing roller 118.
[0011]
Furthermore, when the dynamic pressure of the flowing developer increases due to the speed of the developer conveyance, the force of the developer to penetrate into the inside and the fitting portion of the seal member 132 which is a foamable elastic body is very strong. Thus, there is a case where leakage to the outside of the developing device 4 cannot be prevented. In addition, reducing the particle size of the developer makes it easier for the developer to enter the gap inside the sealing member 132 or the fitting portion, and thus the sealing property is further deteriorated.
[0012]
In order to solve the problem caused by the leakage of the developer, it is usually considered to take measures such as enhancing the sealing property, changing the material of the sealing member, or adding a new seal. However, when the sealing property of the developer leaking part is enhanced by these measures, the escape area of the developer is lost, thereby changing the flow. As a result, the pressure of the developer to a portion having the next weaker sealing property is increased, and a secondary side effect such as leakage of the developer from another portion occurs. If this is repeated, eventually the entire seal configuration may be reviewed, changing or adding the material of the seal member, and even examining the shape change of the fitting portion, and changing the design of the entire developing device. There is a problem that it has to be done and a problem that the cost increases.
[0013]
The present invention changes the conventional idea of using a sealing member to prevent the leakage of the developer, and prevents the unintended leakage at other parts by allowing the leakage of the developer at a specific portion. A developing device is proposed.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a housing for accommodating a developer, an opening formed in the housing for leaking the developer, and storing the developer leaked from the opening. And a storage unit.
[0015]
According to a second aspect of the present invention, in the developing device according to the first aspect, the storage section is detachable from the housing body.
[0016]
According to a third aspect of the present invention, in the developing device according to the first or second aspect, a path for returning the developer in the storage section into the housing is provided.
[0017]
According to a fourth aspect of the present invention, in the developing device according to the first or second aspect, a new developer is separately supplied into the housing while the developer leaked to the storage section is stored.
[0018]
【Example】
FIG. 1 schematically shows a developing device to which the present invention is applied and an image forming apparatus having the same. The image forming apparatus may be any known one such as a copying machine, a facsimile, and a printer, but the image forming apparatus in this embodiment is a printer. Although the image forming apparatus of this embodiment forms a single color image, it may form a color image.
[0019]
The image forming apparatus 100 has a higher heat capacity than plain paper generally used for copying and the like, 90K paper such as OHP sheets, cards, and postcards, thick paper having a basis weight of about 100 g / m ² or more, and envelopes. Any of the large so-called special sheets can be used as a sheet-shaped recording medium for fixing a toner image. The size of the recording medium is generally a size conforming to a general standard such as A4 size or A3 size, but may be a size outside the standard.
[0020]
The image forming apparatus 100 includes a photoconductor drum (hereinafter, referred to as a “photoconductor”) using an organic semiconductor (OPC) as an image carrier that is a cylindrical electrostatic latent image carrier that is driven to rotate in the direction of arrow A. 101), a charging device 102 as charging means for charging the photoconductor 101, and an LD or LD as exposure means for emitting a laser beam 103 for forming a latent image on the charged photoconductor 101 to perform optical scanning. An exposure device (not shown) using LEDs and a developing device 104 as a developing unit for developing a latent image on the photoconductor 101 after exposure are provided.
[0021]
The image forming apparatus 100 also transfers a toner image on the photoconductor 101, which is arranged to face the photoconductor 101 and is obtained by development by the developing device 104, to a sheet-shaped recording medium in a transfer area indicated by reference numeral 105. A transfer device (not shown) as a transfer unit that performs transfer, and a cleaning device 106 as a cleaning unit that collects and cleans the developer remaining on the photoconductor 101 after the transfer.
[0022]
The image forming apparatus 100 further includes a paper feed tray (not shown) on which paper is loaded, a paper feed roller (not shown) serving as paper feed means for feeding the paper loaded on the paper feed tray toward the transfer area 105, and a paper feed roller. A registration roller (not shown) that conveys the paper sent from the paper feed tray to the transfer area 105 at a predetermined timing, and fixes the toner image on the paper on which the toner image on the photoconductor 101 has been transferred by the transfer device. And a fixing device (not shown) as a fixing unit for performing the fixing.
[0023]
The image forming apparatus 100 also has a separating device (not shown) as separating means for separating the sheet on which the toner image has been transferred in the transfer area 105 from the photoreceptor 101. The separation device separates the paper electrostatically attached to the photoconductor 101 by discharging. The separation device may be constituted by a known separation claw. A PCU 10 as a photoconductor unit is configured by the above-described respective configurations illustrated in FIG.
[0024]
The cleaning device 106 is provided with a cleaning blade 11 that rubs against the photoreceptor 101, performs cleaning by a blade method, and has a screw 12 that is a transport screw for guiding the collected developer to the developing device 104. are doing. The charging device 102 has a charging roller 13 that is in contact with the photoconductor 101 and that is driven to rotate. The charging device 102 is not limited to the charging roller 13 and may be a device that charges the photoconductor 101 by another method.
[0025]
The screw 12 conveys the collected developer to the near side in FIG. 1. The collected developer conveyed to the screw 12 is discharged from an unillustrated discharge port, which is a transfer path discharge port formed in the housing 9 of the PCU 10, and falls, and slides down on an unillustrated slope as a fall path. The developer is supplied to the developer container 15 of the developing device 104 through a supply port (not shown) as a recycled toner discharge port formed in the housing 9. The collected toner supplied into the agent container 15 is stirred and mixed with the developer in the agent container 15 and is again subjected to development.
[0026]
The developing device 104 accommodates a two-component developer having a toner and a carrier in the housing 9, and has an agent carrying portion 14 and an agent accommodating portion 15. It is isolated by a seal member 16 provided between the agent carrier 14 and the agent container 15, and the seal member 16 is removed during use. The developer carrier 14 is disposed opposite to the photoconductor 101, and is provided with a developing roller 17 as an agent carrier that performs development by supplying toner in a developer to a latent image formed on the photoconductor 101. And a developing doctor 18 that is arranged to control the supply amount of the developer to the photoconductor 101.
[0027]
The developer container 15 contains most of the developer and has a function of stirring the developer, and has a first stirring unit 19 and a second stirring unit 20. The first agitating member 21 provided in the first agitating section 19 and the second agitating member 22 provided in the second agitating section 20 direct the developer in different directions from each other in the first agitating section 19 and the second agitating section. It is agitated while being conveyed and circulated in the section 20. A toner concentration detection sensor (not shown) that detects the mixing ratio of the toner and the carrier in the developer based on the magnetic permeability is provided below the second stirring unit 20.
[0028]
Then, the developer conveyed through the first stirring section 19 by the first stirring member 21 is attracted to the developing roller 17 by the magnetic force of a fixed magnetic pole (not shown) provided inside the developing roller 17, so that the developer is transferred to the surface of the developing roller 17. And pumped up. The developer on the surface of the developing roller 17 is regulated by the developing doctor 18, so that the amount of the developer after passing through the developing doctor 18 is kept constant, and the triboelectric charging of the developer is promoted.
[0029]
Thereafter, by further rotation of the developing roller 17, the developer on the surface of the developing roller 17 is transported to a position facing the photoconductor 101, and when approaching the photoconductor 101, the developer is exposed to an electrostatic electric field on the surface of the photoconductor 101. In response, the toner in the developer flies over the surface of the photoconductor 101 to perform development. After the development, the developer returns to the developer container 15, is stirred and circulated by the first stirring member 21 and the second stirring member 22, and is supplied with the toner to be used again for development.
[0030]
As described above, the developer is conveyed in the developing device 104. In this process, the developing device 104 serves as a sealing member and the photosensitive roller 17 so that the developer does not leak out of the developing device 104. An entrance seal 31 for preventing toner scattering is provided between the body and the body 101. Further, conventionally, the entire fitting portion between the developing doctor 18 and the housing 9, specifically, the developing device 104 is designed so that the developer regulated by the developing doctor 18 does not rush and leak out of the developing device 104. Has sandwiched the seal member over the entire length in the direction perpendicular to the paper surface of FIG. 1, but as described above, this portion is particularly difficult to prevent the developer from leaking, and has a side effect due to the leak prevention. It is the part that occurs.
[0031]
Therefore, in the developing device 104 to which the present invention is applied, similarly to the seal member 132 in the conventional example, a seal member (not shown) is provided in the longitudinal direction, and the back side in the longitudinal direction, that is, the back side portion in FIG. Is provided with an opening 35 at a fitting portion between the developing doctor 18 and the housing 9 without providing a sealing member over a width of 10 mm in the longitudinal direction, and the developer is intentionally leaked from the opening 35. It is intended to prevent unintended leakage of the developer from other undefined portions.
[0032]
As described above, in this example, the opening 35 is formed by providing a portion where the seal member is not provided, but is expressed as forming the opening 35 in the housing 9. The expression that the opening 35 is formed in the housing 9 includes various forms such as actually forming an opening in the housing 9 and forming an opening by partially cutting out the developing doctor 18. Shall be considered. The width of the opening 35 is not limited to 10 mm, and may be any size as long as the leakage of the developer from the opening 35 is minimized within a range sufficient to prevent the leakage of the developer from other portions.
[0033]
The opening 35 is formed on the back side in the longitudinal direction because a gear train (not shown) for obtaining driving of the developing roller 17, the first stirring member 21, the second stirring member 22, and the like is formed by the developing device 104 in FIG. When the developing roller 17, the first stirring member 21, the second stirring member 22, and the like are driven, the gears are vibrated by the gear train during driving of the developing roller 17, the first stirring member 21, the second stirring member 22, and the like. Because there is. As described above, where the opening 35 is formed in the longitudinal direction is determined in relation to the other configuration of the developing device 104, and is not limited to the back side in the longitudinal direction. May be formed.
[0034]
If the leakage of the developer is only permitted by providing the opening 35, contamination inside the image forming apparatus 100 outside the developing device 104 occurs. Therefore, the lid 9 is formed integrally with the housing 9, A space 37 is provided as a storage section as a space for covering and storing the developer leaked from the opening 35, thereby preventing the leaked developer from being contaminated outside the developing device 104. Note that when contamination by the developer does not pose a problem, such as when the amount of the leaked developer is small, a groove or a depression can be provided below the opening 35.
[0035]
As shown in FIG. 2, the developer leaked from the opening 35 passes through a transport path 39 formed by a cover 38 integrated with the housing 9, and is stored in a tank 40 as a storage unit that is detachable from the main body of the housing 9. It may be guided and collected. By collecting the developer in the tank 40, it is possible to cope with a case where a large amount of leaked developer is generated by operating the developing device 104 for a long time in the developing device 104 which requires long time durability.
[0036]
Therefore, the space 37 is filled with the leaked developer, such as when the developer leaks out of the space 37 and cannot be sufficiently stored due to the structure of the developing device 104. Even in the case where the developer leaks from another portion, the leaked developer can be stored by disposing the tank 40 instead of the developer space 37. Further, since the tank 40 is detachable from the main body of the housing 9, the tank 40 is detached from the main body of the housing 9 when the tank 40 is full or when the tank 40 has accumulated to some extent in the tank 40. As a result, the developer in the tank 40 can be discarded or returned to the agent container 15, and the maintainability is improved.
[0037]
As shown in FIG. 3, the developer that has leaked into the space 37 can be returned to the inside of the agent storage section 15 in the housing 9. That is, a hole 41 is formed as a path for communicating the space 37 with the agent storage unit 15, in this example, the second stirring unit 20, and the leaked developer in the space 37 is returned into the agent storage unit 15. Even if the amount of the leaked developer becomes large over time, the amount of the developer in the agent container 15 may be insufficient, which may cause a problem such as uneven density at the time of image formation, which may hinder development. Absent.
[0038]
In the developer container 15, since the developer overflowing from the first stirring section 19 moves to the second stirring section 20, the second stirring section 20 is not filled with the developer. The pressure of the developer near the opening 35 is released by the developer leaking from the opening 35 moving to the second stirring unit 20, and the developer moving to the second stirring unit 20 is removed from the developer container 15. By returning to the flow in which the developer circulates, stable circulation of the developer is maintained.
[0039]
As shown in FIG. 4, in order to prevent a situation in which the developer in the developer container 15 becomes insufficient due to the leakage of the developer, instead of returning the leaked developer to the developer container 15, a new developer is supplied to the housing. 9 may be supplied to the agent container 15. That is, a cartridge 43 as a supply tank filled with unused developer is attached to the main body of the housing 9, and a communication hole 42 that communicates a space in the cartridge 43 with the agent storage unit 15, in this example, the second stirring unit 20. Is formed, and while the developer leaking from the space 37 is collected and stored in the tank 40, the developer in the cartridge 43 can be separately supplied into the agent container 15.
[0040]
The developer gradually deteriorates as the circulation is repeated in the developing device 104, and impurities such as paper dust are mixed in from the peripheral portion of the developing roller 17 to lower the developing ability, but replenish the unused developer. Thus, it is possible to maintain the image quality for a long period of time by suppressing a decrease in the developing ability. Therefore, when replenishing unused developer, since the developer is positively discharged from the opening 35 for the purpose of replacing the developer, the amount of leakage from the opening 35 is reduced by increasing the size of the opening 35 or the like. You can do more.
[0041]
As a timing of supplying the new developer from the cartridge 43, the amount of the developer leaking is estimated in advance by an experiment or the like, and a constant amount of the developer is continuously or intermittently newly supplied accordingly, or It is also possible to provide a device that detects the amount of leaked developer with a sensor or the like in the tank 40 or the like and supplies the amount of developer corresponding to the detected amount. The developing device 104 to which the cartridge 43 and the communication hole 42 are applied may be of a type in which the leaked developer is stored in the space 37 instead of being collected in the tank 40. As described above, the stable circulation of the developer is maintained by replenishing the second developer with the new developer.
[0042]
Since the image forming apparatus 100 is configured as described above, the power of the image forming apparatus 100 is turned on by a predetermined operation by the operator, or after the image forming apparatus 100 shifts from the standby state to the operation state, the image forming apparatus 100 starts image formation. When a well-known operation is performed, the photosensitive member 101 uniformly charged by the charging process by the charging device 102 is rotated by the rotation in the direction of the arrow A to expose the photosensitive member 101 with the laser beam 103 irradiated according to data input from the outside. , A developing process performed by development by the developing device 104, a transfer process by the transfer device, and a cleaning process by the cleaning device 106, and then the charging process is performed again.
[0043]
The toner image transferred on the sheet in the transfer step is fixed on the sheet in a fixing step in a fixing device. The sheet on which the toner image has been fixed is discharged out of the image forming apparatus 100. In such an image forming process, the developer collected in the cleaning process is supplied to the developing device 104 again. Further, in such a developing process, the leakage of the developer from the undefined portion of the developing device 104 is prevented, and the inside of the image forming apparatus 100 and the like are not contaminated. The present invention is not limited to a two-component developer and can be applied to a developing device using a one-component developer.
[0044]
【The invention's effect】
The present invention has a housing for storing the developer, an opening formed in the housing for leaking the developer, and a storage unit for storing the developer leaked from the opening, so that the developer leaks. Is allowed by a specific portion, that is, an opening, so that it is possible to provide a developing device capable of preventing leakage of the developer from other unspecified portions.
[0045]
If the storage section is detachable from the housing body, it is easy to secure the storage section, and it is possible to easily store a large amount of the leaked developer. When the container becomes full or when the leaked developer accumulates in the storage part to some extent, the storage part can be detached from the housing body and the developer in the developer can be discarded or returned to the housing. A developing device with improved performance can be provided.
[0046]
By providing a path for returning the developer in the storage unit to the inside of the housing, the maintenance of the developer in the storage unit is not required for returning the developer in the storage unit to the housing. It is possible to provide a developing device that can prevent a problem that the amount of the developer in the housing becomes insufficient and the density is not uniform during image formation, thereby hindering the development even if the amount of the developer becomes large.
[0047]
If the developer leaked to the storage part is stored and new developer is separately supplied to the above-mentioned housing, the developer is deteriorated with time by replenishing the unused developer and developing. It is possible to provide a developing device that can prevent the deterioration of the developing ability due to the contamination of the device with impurities such as paper dust and the like, maintain the developing performance, and contribute to maintaining the image quality for a long time.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a developing device to which the present invention is applied and an image forming apparatus having the same.
FIG. 2 is a side sectional view of another example of the developing device provided in the image forming apparatus shown in FIG.
3 is a side sectional view of still another example of the developing device provided in the image forming apparatus shown in FIG.
4 is a side sectional view of still another example of the developing device provided in the image forming apparatus shown in FIG.
FIG. 5 is a side view of a conventional developing device.
[Explanation of symbols]
9 Housing 35 Opening 37 Space 40 as storage section Tank 41 as storage section Path 104 Developing means

Claims (4)

A housing for housing the developer,
An opening formed in the housing for allowing the developer to leak out,
A storage unit for storing the developer leaked from the opening. The developing device according to claim 1, wherein the storage unit is detachable from the housing body. 3. The developing device according to claim 1, further comprising a path for returning the developer in the storage section into the housing. 3. The developing device according to claim 1, wherein a new developer is separately supplied into the housing while the developer leaked to the storage section is stored.

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