JP2005140971A - Scattering dust suction device, developing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scattering dust suction device that is excellent in saving on a space and suction efficiency, and also to provide a developing device and an image forming apparatus. <P>SOLUTION: The scattering dust suction device is disposed downstream of a latent image carrier in its rotating direction and opposite to the latent image carrier, and sucks dust containing toner and a magnetic carrier scattering in a narrow area between the latent image carrier and a developer supply device which supplies developer to the latent image carrier. The scattering dust suction device includes: a suction duct which has a plurality of suction ports and a plurality of air passages which independently communicate with the suction ports and along which currents of air for suction flow independently, each air passage being disposed such that the normal vector of the suction port is nonparallel to the direction of the movement of the current of air in the air passage; and a forcible air creating device which connects to each air passage and forcibly creates a current of air within the air passage in order to suck scattering dust from the corresponding suction port via the air passage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a scattered dust suction device, a developing device, and an image forming apparatus, and more particularly to a mechanism for sucking dust such as toner and magnetic carrier scattered in a developing device used in an image forming apparatus such as a copying machine, a facsimile machine, and a printer.

  Conventionally, in a magnetic brush type developing device in an image forming apparatus, a developer containing toner and a magnetic carrier is generated by a magnetic field formed by a magnet built in a developing sleeve as a developer carrying member provided in an opening of a developing device casing. A magnetic brush is formed, and the magnetic brush is conveyed to a gap between a photosensitive drum as a latent image carrier and a developing sleeve to develop a latent image on the photosensitive drum.

  However, in the developing device in the image forming apparatus, the toner and the carrier in the device are easily scattered from the opening of the developing device casing provided with the developing sleeve. The toner or carrier dust scattered outside from the lower part of the developing device contaminates the inside of the image forming apparatus and may contaminate the operator's hands during processing such as a paper jam. There is a problem that it adheres to electrical parts and causes noise or the like, or adheres to a transfer portion of the transfer sheet as an image holding member and soils the transfer sheet.

  Several techniques for solving such problems have been proposed. As one of them, in Patent Document 1, a side sheet made of a porous air-permeable sheet for preventing scattering is provided at both ends of the opening of the developing case, so that toner does not go out of the developing case and only the air is outside. Can be put out. In Japanese Patent Application Laid-Open No. 2004-228561, an air flow generation unit that generates an air flow in the direction from the outside to the inside of the developing device is provided in the gap between the photoconductor and the carrier recovery unit. Further, in Patent Document 3, the airflow blown into the corona discharge device is made uniform, so that the charged product is uniformly discharged or charged, so that excess product is not retained.

  However, Patent Documents 1 and 2 are particularly effective in preventing the amount of scattering at both ends of the developing case opening where there is much scattering, but the floating toner carrier is only applied to the end of the developing case and a part of the photosensitive member / developing sleeve. Even if a filter or a collecting means for preventing this is installed, the floating toner carrier is scattered by the air current blown out from the inside of the developing casing, which is insufficient as a countermeasure. Therefore, it is difficult to sufficiently remove dust such as scattered toner and carrier for recent development methods with higher speed and smaller size. Further, in Patent Document 3, uniform charging is directed by uniformly performing a suction airflow in the wire axial direction. However, in recent miniaturization designs, installation of a mechanism that generates airflow perpendicular to the unit's photoconductor, developing sleeve, charging wire, etc., installs each unit of the fixing system and transfer system at a location adjacent to the mechanism. Because it is common to do, it is practically difficult. In view of this, a scattering dust suction device shown in FIG. 6 has been proposed, and will be described below with reference to the drawings.

FIG. 6 is a schematic sectional view showing a configuration of a developing device to which a conventional scattered dust suction device is applied. Note that the developing device shown in the figure is an example of a developing unit using a two-component developer. In this drawing, in this magnetic brush type developing device 60, a magnetic brush is formed by a developer 66 containing toner and a carrier by a magnetic field formed by a magnet built in a developing sleeve 62 provided in an opening of a developing device casing. Then, the magnetic brush is conveyed to a gap between the photosensitive drum 61 as a latent image carrier and the developing sleeve 62, charged on the photosensitive drum 61 charged by the charging device 65 and exposed by an exposure device (not shown). Develop the latent image into a visible image. Further, the developer 66 is supplied by a developer supply device 63, stirred by a screw or paddle stirrer 64, and conveyed in the long axis direction. Here, as described above, in the development nip region 67 shown in FIG. 6, there is dust such as scattered toner and carrier. In addition, due to the recent trend toward downsizing of image forming apparatuses, it is common that the space around the developing unit is utilized as much as possible with no gaps. For example, a transfer system and a fixing system are installed on the bottom side B of the developing device 60, and development units of different colors are installed adjacent to the side surface C of the developing device 60. For this reason, when trying to suck and discharge dust such as scattered toner and carrier using an external forced airflow, it is unavoidable to use the region A in a direction perpendicular to the paper surface. In this case, the layout of the suction duct 68 is as shown in FIG. It is most efficient in terms of arrangement layout to be installed in a proximity position parallel to the long axis direction of the photoconductor 61 and the developing sleeve 62 and downstream of the rotation direction. Moreover, it can be expected that the entire dust generated in the long axis direction is sucked by one duct.
JP-A-5-119626 Japanese Patent Laid-Open No. 10-247042 JP-A-10-198128

  However, in order to suck the dust such as scattered toner and carrier generated between the photosensitive member 61 and the developing sleeve 62 in FIG. 6, a flow velocity / pressure difference of a certain airflow or more is naturally necessary. As shown in FIG. 8A, which is a plan view of the suction duct of the dust suction device, and in FIG. 8B, which is a sectional view taken along the line XX ′ of FIG. If only the slit-like suction port 69 is provided, the flow rate is obtained only in the region closest to the forced air flow generator (not shown), and the air flow is hardly obtained on the facing side. As can be seen from FIG. 9, which is a characteristic diagram showing an example of the calculation result of the airflow in such a case, as shown in FIG. 8 (a), it corresponds to the duct central axis (XX ′ line) of the suction duct 68. )) From the flow velocity distribution at the slit-like suction port, the distance from the center is in the negative direction, that is, the closer to the forced airflow generator side, the higher the flow velocity, and the distance from the center is in the positive direction, that is, farther from the forced airflow generator side. The flow rate is slow. In FIG. 8, it is assumed that the forced airflow generator (not shown) has a gauge pressure of 100 Pa, the duct is a rectangular parallelepiped, has a cross-sectional area of 10 × 10 mm, a length of 300 mm, and a fluid of 25 ° C. As can be seen from FIGS. 8 and 9, when the distance from the vicinity of the forced airflow generation device (not shown) (the left region in the figure) increases, the flow velocity decreases rapidly, that is, the suction force decreases.

  Therefore, a case will be described in which suction ports having a certain size are provided at intervals rather than a continuous slit shape on the suction duct as shown in FIG. FIG. 10A is a plan view of a conventional suction duct, and FIG. 10B is a cross-sectional view taken along the line Y-Y ′ of FIG. In this case, the flow velocity distribution on the straight line C in the suction duct is as shown in FIG. 11, which is somewhat smaller than that in FIG. 9, but the suction force tends to decrease far away from the forced air flow generator not shown. Is the same. This is because the pressure is released to the atmospheric pressure at the closest suction port 69-1, and the energy for dynamic pressure is suddenly lost, so that energy for suction at a point downstream from that is lost. is there. However, if a suction port is not provided in the first place, it is impossible to perform suction, which causes a dilemma.

  As described above, it is difficult to obtain a uniform suction effect in the major axis direction of the photoreceptor, the developing sleeve, or the charging device only by simply processing the hole shape in the upper part of the suction duct.

  The present invention has been made to solve these problems, and it is an object of the present invention to provide a scattered dust suction device, a developing device, and an image forming device that are excellent in space saving and excellent in suction efficiency.

  In order to solve the above problems, the scattered dust suction device of the present invention is disposed on the downstream side in the rotation direction of the latent image carrier and opposite to the latent image carrier, and supplies the developer to the latent image carrier. A device for sucking dust including toner and magnetic carrier scattered in a constricted area on the latent image carrier side in the developer supply device, for communicating with and suctioning a plurality of suction ports and each suction port individually A plurality of air flow paths through which the air flow flows independently, and a suction duct provided with each air flow path so that the normal vector of the suction port is not parallel to the direction of movement of the air flow in the air flow path, and In order to suck dust scattered from each suction port through the air flow path, it is characterized in that it has a forced air flow generation device that is connected to each air flow path and forcibly generates an air flow in each air flow path. Therefore, it is possible to provide a scattered dust suction device that is excellent in space saving and excellent in suction efficiency.

  In addition, by varying the cross-sectional area of each air flow path at the connecting portion connected to the forced air flow generating device according to the desired flow rate for each suction port, dust scattering including the most toner and magnetic carrier is most often generated. By specifying the suction port for the location, it is possible to further increase the dust suction effect.

  In addition, a forced airflow generation control device is provided to control the operation of the forced airflow generation device and the flow rate of the airflow generated by the forced airflow generation device, depending on the developer concentration necessary for image formation, the image density, or the humidity near the device. By controlling the operation of the forced airflow generator and the flow rate of the airflow, the energy saving effect and the suction efficiency can be further improved.

  Further, a developing device as another invention is characterized by having the above scattered dust suction device.

  Furthermore, an image forming apparatus as another invention is characterized by having the developing device.

  According to the scattered dust suction device of the present invention, it is excellent in space saving and the suction efficiency can be improved in a design that is aimed at downsizing like a recent developer unit.

  The scattered dust suction device of the present invention has a suction duct and a forced airflow generation device. The suction duct has a plurality of suction ports and a plurality of air flow paths that individually communicate with each suction port and through which airflow for suction flows independently. Each air flow path is provided so as not to be parallel to the moving direction of the air flow in the air flow path. In addition, the forced air flow generator is connected to each air flow path to force air flow into each air flow path in order to suck the dust containing toner and magnetic carrier scattered from each suction port through each air flow path. It is a device that generates. Therefore, it is possible to improve the suction efficiency at each suction port without being affected by the mutual air flow paths, and to provide a scattered dust suction device that can be installed in a small space and has excellent space saving performance.

  FIG. 1 is a view showing a configuration of a suction duct in a scattered dust suction device according to an embodiment of the present invention. 1A is a plan view, FIG. 1B is a cross-sectional view taken along the line A-A ′, and FIG. 1C is a perspective view. The suction duct 10 in the scattered dust suction device of the present embodiment shown in each figure is a rectangular parallelepiped, for example, a cross-sectional area of 10 × 10 mm and a length of 300 mm, and on the upper surface, a plurality of, for example, a width of 2 mm and a length of 30 mm. For example, three suction ports 11-1 to 11-3 are installed at equal intervals. Further, a forced air flow generator (not shown) is installed at one end of the suction duct 10, and a common opening 14 communicating with the suction port of the forced air flow generator is shown in FIGS. The air flow in the direction of the arrow is generated. Further, as shown in FIGS. 1A to 1C, a partition wall 12 is provided in the suction duct 10. The partition wall 12 corresponds to each of the suction ports 11-1 to 11-3, and is installed so that the air flow path from the forced air flow generation device does not intersect the main air flow path of another suction port, and each suction port 11-1 To 11-3 individually communicate with the air flow paths 13-1 to 13-3. At this time, it is preferable to define a straight line B on the partition wall 12 so as to pass through the centers of the suction ports 11-1 to 11-3. The straight line B is parallel to the major axis direction of the air flow paths 13-1 to 13-3. Here, FIG. 2 shows the flow velocity distribution on the straight line B when the gauge pressure of the forced airflow generator is 100 Pa. In addition, the flow rate drawn from the surroundings through the suction port is shown in the following table.

  Thus, a much more uniform flow rate can be obtained as compared with the structure of the conventional suction duct shown in FIGS. As described above, in a design oriented toward miniaturization like a recent developer unit, a scattered dust suction device having a suction duct which is a good suction mechanism excellent in space saving is provided.

  FIG. 3 is a block diagram showing the overall configuration of the scattered dust suction device of the present invention. In the figure, a forced airflow generation control device 21 is connected to the forced airflow generation device 20 connected to the suction duct 10, and the input voltage of the forced airflow generation device 20 can be controlled. Further, the forced airflow generation control device 21 is connected with an image density sensor 22 and a toner concentration sensor 22, and when the image density is lower than a certain image density expected by detection from each sensor, the input voltage to the forced airflow generation device 20 is detected. Can be cut or its voltage can be lowered. Although it depends on the characteristics of the toner, it is an empirical fact that the concentration of scattered toner that is scattered in the air decreases as the ambient humidity increases. Therefore, when the humidity detected by the humidity sensor 23 that detects the humidity in the device connected to the forced airflow generation control device 21 exceeds a certain humidity, the input voltage to the forced airflow generation device 20 is cut or the voltage is cut. Can be lowered. As described above, by suppressing the operation of the forced airflow generation device 20 according to the image forming conditions and the environmental conditions, it is possible to further reduce energy consumption and noise.

  In addition, for example, when the image formation is not performed or during startup, the forced airflow generation device 20 can be operated in the reverse direction by the control from the forced airflow generation control device 21. When a flow in a certain direction is always generated, a vortex is generated in a part of the suction duct and the partition wall, and scattered toner may stay there, and secondary adhesion may occur. Therefore, the operation of the forced airflow generation device 20 is reversed, that is, the inside of the suction duct is set to a positive pressure, thereby generating a flow in such a region and cleaning the staying scattered toner again. Can be obtained.

  In the suction duct in the scattered dust suction device of the present invention shown in FIG. 1, as shown in FIG. 4 (a), the cross-sectional areas a to c of the air flow paths 13-1 to 13-3 respectively communicating with the suction ports. However, the present invention is not limited to this, and the flow rate can be controlled by varying the cross-sectional area of each air flow path as shown in FIG. The suction area 11 of the air channel 13-1 communicating with the near suction port 11-1 is smaller than the sectional area b of the air channel 13-2 communicating with the suction port 11-2, and further away from the forced air flow generator side. -3 is made larger than the cross-sectional area b of the air flow path 13-2 communicating with the suction port 11-2 so that the flow rate at each of the suction ports 11-1 to 11-3 is almost equal. Adjust to equalize or set the cross-sectional area of the specified suction port The flow rate of the specified suction port can be arbitrarily adjusted by Rukoto.

  FIG. 5 is a schematic cross-sectional view showing the configuration of the image forming apparatus of the present invention. In the figure, in the image forming apparatus 50, an appropriate charged state is formed on the surface of the photoreceptor 51 by the charge control device 52, and an electrostatic latent image is formed by a laser from the exposure device 53 in accordance with the image information. . Next, toner is supplied from the developer supply device 54 to a location corresponding to the electrostatic latent image, and the electrostatic latent image is visualized. A large amount of scattered toner is generated in the nip region, which is a region close to the photosensitive member 51 and the developing sleeve 55 of the developer supply device 54, but below this is a suction duct 10 which is a part of the scattered dust suction device described above. By installing, scattering developer can be reduced. As a result, the visible image of the photoconductor 51 that has formed a good image state is transferred by the transfer device 56 to the transfer paper on which the toner adhered on the latent image has been conveyed. Further, the excessively adhered toner is removed by the cleaning device 57 to form one cycle of image formation.

  In addition, this invention is not limited to the said Example, It cannot be overemphasized that various deformation | transformation and substitution are possible if it is description in a claim.

It is a figure which shows the structure of the duct for suction in the scattering dust suction apparatus which concerns on one Example of this invention. It is a characteristic view which shows the flow-velocity distribution on the straight line B of the duct for suction in a present Example. It is a block diagram which shows the whole structure of the scattering dust suction apparatus of this invention. It is a figure which shows the structure of the duct for suction in the scattering dust suction apparatus which concerns on another Example of this invention. 1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus of the present invention. It is a schematic sectional drawing which shows the structure of the developing device to which the conventional scattered dust suction device is applied. It is a perspective view which shows the layout of the duct for suction in the conventional scattering dust suction apparatus. It is a figure which shows the structure of the duct for suction of the conventional scattering dust suction apparatus. It is a characteristic view which shows an example of the calculation result of the airflow in the duct for suction of FIG. It is a figure which shows another structure of the duct for suction of the conventional scattering dust suction apparatus. It is a characteristic view which shows the flow-velocity distribution on the straight line C in the duct for suction of FIG.

Explanation of symbols

10; duct for suction, 11-1 to 11-3; suction port,
12; Partition, 13-1 to 13-3; Air channel, 14; Common opening,
20; forced airflow generation device, 21; forced airflow generation control device,
22; Image density sensor, 23; Toner density sensor, 24; Humidity sensor,
50; Image forming device, 51; Photoconductor, 52; Charge control device,
53; Exposure device, 54; Developer supply device, 55; Development sleeve,
56; Transfer device, 57; Cleaning device.

Claims (8)

Scattering in the constricted area between the downstream side of the latent image carrier in the rotation direction and the developer supply device disposed opposite to the latent image carrier and supplying the developer to the latent image carrier. In the scattered dust suction device that sucks dust containing toner and magnetic carrier
A plurality of suction ports, and a plurality of air flow paths that individually communicate with each suction port, and the air flow for suction flows independently, and the normal vector of the suction port is the air flow in the air flow path A suction duct provided with each air flow path so as not to be parallel to the moving direction;
A forced air flow generating device that forcibly generates an air flow in each air flow path connected to each air flow path in order to suck the scattered dust from each suction port via each air flow path; The scattered dust suction device characterized by that.   The scattered dust suction device according to claim 1, wherein a cross-sectional area of each of the air flow paths in a connection portion connected to the forced air flow generation device is varied according to a desired flow rate for each of the suction ports.   The scattered dust suction device according to claim 1, further comprising a forced airflow generation control device that controls the operation of the forced airflow generation device and the flow rate of the airflow generated by the forced airflow generation device.   A developer concentration detecting means for detecting in advance a developer concentration necessary for image formation is provided, and the forced airflow generation control device operates the forced airflow generation device according to the developer concentration by the developer concentration detection means. And the scattered dust suction device according to claim 3 for controlling the flow rate of the airflow.   Image density detection means for detecting in advance the density of an image formed by image formation is provided, and the forced airflow generation control device controls the operation of the forced airflow generation device and the flow rate of the airflow according to the image density by the image density detection means. The scattered dust suction device according to claim 3.   4. The scattering according to claim 3, further comprising humidity detecting means for detecting humidity in the vicinity of the apparatus, wherein the forced airflow generation control device controls the operation of the forced airflow generation apparatus and the flow rate of the airflow according to the humidity by the humidity detection means. Dust suction device.   A developing device comprising the scattered dust suction device according to claim 1. An image forming apparatus comprising the developing device according to claim 7.

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