JP2009169308A - Developing device and image forming apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of cooling a developer and a layer thickness regulating member in a developing tank and further collecting scattered toner, and an image forming apparatus provided with the developing device.
A doctor blade 13 is supported on a side wall of a support 14 in surface contact and is provided at the bottom of a developing tank 12. The inside of the support 14 is hollow and generates an air flow from the outside of the developing tank 12 to the outside of the developing tank 12 through the first communication pipe 53, the internal space of the support 14, and the second communication pipe 54. Let The developer and the doctor blade 13 that come into contact with the support 14 with this airflow are cooled by air and cooled. In addition, an air flow from the gap between the cover member 16 and the doctor blade 13 through the through hole 17 to the inside of the support 14 is also generated, and the scattered toner generated near the layer thickness regulation position by the air flow is generated inside the support 14. Can be recovered and removed to the outside of the developing tank 12.
[Selection] Figure 2

Description

  The present invention relates to a developing device that performs image formation using an electrophotographic method, and an image forming apparatus including the developing device.

  In an image forming apparatus that employs an electrophotographic system, a latent image formed on the surface of a photoconductor is developed by supplying toner as a developer component from a developing device and developing it. A toner image is formed, the toner image is further transferred onto a recording paper as a transfer medium, and the toner image transferred onto the recording paper is fixed to form a robust recording image.

  In recent years, as the efficiency of office work in which image forming apparatuses such as copiers and printers are used has been further promoted, image forming apparatuses have improved image forming processing capability, for example, output per unit time. It is desired to improve the image forming processing speed expressed by the number of recording sheets that can be printed.

  In an image forming apparatus (called a high speed machine) having a high image forming processing speed, the developer needs to have a longer life compared to an image forming apparatus (called a medium / low speed machine) having a medium or low image forming processing speed. Is done. In a high-speed machine, since the number of images formed per unit time is large, the amount of developer consumed per unit time, more strictly, the amount of toner is large, and the frequency of exposure to stirring and conveying is high. This is because, if the life is about the same as that of the developer used in the medium / low speed machine, the life of the toner is exhausted in a short period of time, and the maintenance frequency for the developer increases.

  One solution to such a problem is to enlarge the developing device. By enlarging the developing device and increasing the amount of developer that can be accommodated, it is possible to cope with a large amount of developer consumption by a high speed machine, reduce the frequency of exposure to agitation transport, and extend the life. . However, there are many cases where the developing device cannot be made large due to structural limitations of the image forming apparatus. In the case of a system in which toner is replenished to the developer tank facing the developer carrier, in order to supply a uniform developer to the developer carrier by sufficiently stirring the high-speed machine when the developing device is slightly enlarged. Therefore, it is difficult to control the toner concentration of the developer.

  Therefore, as another countermeasure, it has been proposed to reduce the stress applied to the developer as much as possible. For example, the distance between the layer thickness regulating member and the developer carrying member, that is, the doctor gap (DG) is increased. However, in order to achieve high image quality, DG must be made as narrow as possible, which has the problem of conflicting with low stress.

  Further, although related to reducing the stress, the stress applied to the developer increases, and at the same time, the amount of heat generated in the developing device increases. Most of this is frictional heat generated when the developer passes through the gap between the layer thickness regulating member and the developer carrier. This heat also changes the characteristics of the developer, and the fixing due to the softening of the toner. Due to the deterioration of the characteristics, the initial developing ability cannot be stably continued.

  Another problem with high-speed machines is that toner particles are likely to scatter from the developing magnet roller, which can contaminate the inside and outside of the apparatus.

  As a conventional technique for solving these problems, in the image forming apparatus described in Patent Document 1, the surface of the developing roller is covered with a covering member on the upstream side of the developing portion and sucked with a suction fan. By doing so, an air flow is generated between the covering member, the developing roller and the doctor blade, and the scattered toner can be sucked and the heated sleeve, carrier, toner and doctor blade can be cooled.

  In addition, in the image forming apparatus described in Patent Document 2, a high heat conduction member is provided in contact with the developer, in contact with the layer thickness regulating member, and further, a heat radiating fin is provided on the high heat conduction member to cool the developer. ing.

JP 2002-278268 A JP 2005-266249 A

  In the image forming apparatus described in Patent Document 1, it is necessary to cover the developing roller with a covering member to form an air path. With such a configuration, the entire developing apparatus becomes large and the image forming apparatus can be downsized. Not suitable for. Further, since the air is cooled only by flowing an air flow on the outer surface of the member to cool the doctor blade that is the hottest, the cooling efficiency is poor and the doctor blade is not sufficiently cooled.

  Patent Document 2 discloses cooling the toner, but has a structure in which the heat is released to the doctor blade, and further, no countermeasure is taken into account for the scattered toner.

  An object of the present invention is to provide a developing device capable of cooling a developer and a layer thickness regulating member in a developing tank and further collecting scattered toner, and an image forming apparatus including the developing device.

The present invention is provided in an image forming apparatus that forms an image using an electrophotographic method, and is provided rotatably and has a developer carrier that carries the developer, and is attached to the support so that the developer carrier is mounted on the developer carrier. In the developing device provided with a layer thickness regulating member that regulates the layer thickness of the developer in the developing tank,
The support has a space inside, is provided at the bottom of the developing tank, and supports the layer thickness regulating member in surface contact with the side wall,
The developing device further includes an air flow generating means for generating an air flow from the outside of the developing tank to the outside of the developing tank through the internal space of the support.

Further, the present invention is provided with a through hole that penetrates the layer thickness regulating member and the side wall supporting the layer thickness regulating member to the internal space of the support,
A cover member provided at a predetermined interval from the layer thickness regulating member;
A gap is formed between the cover member and the layer thickness regulating member from the layer thickness regulating position by the layer thickness regulating member to the bottom of the developing tank,
The gap and the internal space of the support are communicated with each other through the through hole.

  In the present invention, a plurality of the through holes are provided, and among the plurality of through holes, the opening diameters of the through holes provided at both ends in the longitudinal direction of the support are larger than the opening diameters of the other through holes. It is large.

The present invention also includes a storage container for storing new toner to be replenished into the developing tank,
The airflow generation means introduces an airflow directed to the outside of the developing tank into the storage container.

  In the present invention, the support has a double structure, and the inner support is configured to be detachable in the longitudinal direction with respect to the outer support.

  The present invention is characterized in that, of the side walls of the support, a side wall adjacent to the developer stirring member has a curved shape along the outer shape of the developer stirring member.

  In the invention, a side wall adjacent to the developer carrier among the side walls of the support has a curved shape along the outer shape of the developer carrier.

Moreover, this invention is characterized by the thickness of the side wall which fixes and supports the said layer thickness control member among the side walls of the said support body being more than the thickness of a layer thickness control member.
According to another aspect of the present invention, there is provided an image forming apparatus comprising the above developing device.

  According to the present invention, the support that supports the layer thickness regulating member in surface contact with the side wall has a space in the inside thereof and is provided at the bottom of the developing tank.

  The air flow generation means generates an air flow from the outside of the developing tank to the outside of the developing tank through the internal space of the support.

  As a result, the support has a heat exchange function using air as a medium, and the developer and the layer thickness regulating member in contact with the support are cooled by air.

  According to the present invention, the gap between the cover member and the layer thickness regulating member and the support body through a through-hole penetrating the layer thickness regulating member and the side wall supporting the layer thickness regulating member. Communication with the interior space.

  When an air flow is generated by the air flow generating means, an air flow is generated from the through-hole to the inside of the support body from the layer thickness regulation position toward the bottom of the developing tank. By this air flow, scattered toner generated near the layer thickness regulation position can be collected inside the support and removed outside the developing tank.

  Moreover, according to this invention, the opening diameter of the through-hole provided in the longitudinal direction both ends of the said support body is larger than the opening diameter of other through-holes among several through-holes.

  There is a structural gap between the axial end portions of the developer carrier and the side wall of the developing tank. The toner that scatters through the gap can be efficiently collected through the through hole having a large opening diameter.

According to the invention, the airflow generating means introduces an airflow toward the outside of the developing tank into the replenishment toner storage container.
Thereby, the collected toner can be reused.

  Moreover, according to this invention, an inner side support body is comprised with respect to an outer side support body so that attachment or detachment is possible in a longitudinal direction.

  Thereby, the toner adhering to the inner wall surface of the removed inner support can be easily cleaned.

  According to the invention, of the side walls of the support, the side wall close to the developer stirring member has a curved shape along the outer shape of the developer stirring member.

  According to the invention, of the side walls of the support, the side wall close to the developer carrier has a curved surface shape along the outer shape of the developer carrier.

  Thus, the developer can be transported to the layer thickness regulation position smoothly and without applying stress as much as possible without hindering the transport of the developer in the developing tank by the support.

  According to the invention, among the side walls of the support, the thickness of the side wall that fixes and supports the layer thickness regulating member is equal to or greater than the thickness of the layer thickness regulating member so that the layer thickness regulating member does not deform. Sufficient mounting strength can be ensured.

According to the invention, there is provided an image forming apparatus comprising the above developing device.
By effectively cooling the developer and the layer thickness regulating member, the characteristics of the developer can be maintained for a long period of time, and high-quality image formation can be realized.

  FIG. 1 is a diagram showing a simplified configuration of an image forming unit portion of an image forming apparatus 1 including a developing device 10 according to an embodiment of the present invention.

  The developing device 10 is provided in an image forming unit portion that mainly forms an image of the electrophotographic image forming apparatus 1. The image forming unit includes a photosensitive member 2 having a photosensitive layer on which an electrostatic latent image is formed, a charging device 3 that uniformly charges the surface of the photosensitive member 2, and light corresponding to image information on the surface of the photosensitive member 2. Of the exposure device 4 for forming an electrostatic latent image by scanning the developing device 10, a developing device 10 for supplying a developer to the surface of the photosensitive member 2 to develop the electrostatic latent image to form a toner image, The image forming apparatus includes a transfer device 5 that transfers a toner image formed on the surface onto a recording medium such as a recording paper, and a cleaning device 6 that cleans toner remaining on the surface of the photoreceptor 2 after being transferred to the recording paper. The

  The developing device 10 generally includes a developing roller 11 that carries a developer, a developing tank 12 that contains the developer, a first agitating and conveying member 28 that agitates and conveys the developer in the developing tank 12, and a second agitating member. 29.

  In the present embodiment, the developing roller 11 is a so-called magnet roller that includes a developing sleeve 22 that includes a magnet member 21 and is rotatably provided on the outer periphery of the magnet member 21. The magnet member 21 is made of, for example, a permanent magnet piece, and N poles and S poles are arranged approximately alternately at a predetermined angle in the circumferential direction to form a cylindrical shape as a whole. The developing sleeve 22 is a cylindrical member made of a nonmagnetic material such as resin or aluminum, and is provided so as to be rotatable around the magnet member 21. The developing roller 11 faces the photosensitive member 2 and is arranged so that its axis is parallel to the rotational axis of the photosensitive member 2, and is supported by the frame portion of the main body of the developing device 10.

  As the developer carried on the developing roller 11, a two-component developer containing toner and carrier is used. The developing roller 11 attracts the carrier carrying the toner by the magnetic force of the magnet member 21 to form a magnetic brush in which the developer is linked in a spike shape on the surface of the developing sleeve 22. Thus, the developer is carried on the developing roller 11 in the form of a magnetic brush. A toner having a charge in the developer forming the magnetic brush is supplied from the developing roller 11 to the photoconductor 2 according to the potential difference between the developing roller 11 and the photoconductor 2 to develop the electrostatic latent image, and the toner image Form.

  The developing tank 12 is a container member made of, for example, hard synthetic resin and having an approximately rectangular parallelepiped shape in appearance.

  In the developing tank, the second agitating and conveying member 29 is provided on the side close to the developing roller 11 to convey the pumped developer to the developing roller 11, and the first agitating and conveying member 28 is separated from the developing roller 11. The newly replenished toner is stirred on the side and the developer is conveyed to the second stirring member 29. An intermediate wall member 42 is provided between the first stirring and conveying member 28 and the second stirring and conveying member 29. The intermediate wall member 42 is a flat plate member made of, for example, synthetic resin, and is provided so as to extend in the longitudinal direction of the developing tank 12 and rise from the bottom of the developing tank 12. However, since the intermediate wall member 42 is formed to have a length shorter than the length of the developing tank 12 in the longitudinal direction, the intermediate wall member 42 passes through the gap between the intermediate wall member 42 and the developing tank 12 in the tank. The developer flows from the first stirring / conveying member 28 toward the second stirring / conveying member 29, and at one end, the developer flows from the second stirring / conveying member 29 toward the first stirring / conveying member 28.

  In the developing device 10, a sensor (not shown) for detecting the amount of developer in the developing tank 12 is provided, for example, at the bottom of the developing tank 12, and a magnetic permeability sensor or a piezoelectric detection type sensor is used as the sensor. . Therefore, as the developer amount, the toner amount in the developer, in other words, the toner concentration which is the blending ratio of the carrier and the toner is detected.

  In the developing device 10, the control unit operates the toner hopper 60 according to the detection output of the toner density, and supplies the developing tank 12 with the amount of toner reduced by the use of toner by development. New toner is supplied from the toner hopper 60.

  The toner hopper 60 is a container member made of, for example, hard synthetic resin. The toner hopper 60 accommodates the toner 62 in its internal space, and drives the toner replenishing roller 64 in accordance with an operation command from the control unit. The toner 62 is replenished via the connecting portion 63. The toner replenishing roller 64 is provided directly above the first agitating and conveying member 28 so that the outer periphery thereof can rotate while being in sliding contact with the toner replenishing port. The toner replenishing roller 64 is provided with a cylindrical porous elastic member such as foamed urethane around a core metal, and the toner held by the porous elastic member of the toner replenishing roller 64 in the toner hopper is The toner is removed from the toner supply roller 64 by the rubbing between the toner supply port and the toner supply roller 64 and supplied to the developing tank 12.

  In the present invention, a support for supporting a doctor blade (hereinafter simply referred to as “doctor”) as a layer thickness regulating member is provided at the bottom of the developing tank 12, and a cooling airflow is generated inside the support. It is characterized by doing.

  FIG. 2 is a schematic view showing the structure of a doctor support (hereinafter, sometimes simply referred to as “support”). 2A is a diagram viewed from the axial direction of the developing roller 11, and FIG. 2B is a diagram orthogonal to the axial direction of the developing roller 11 and viewed from the photosensitive member 2 side in a substantially horizontal direction. is there. The side wall of the developing tank 12 is not shown so that the structure of the support 14 can be understood.

  The doctor support 14 is a cylindrical structure disposed inside the developing tank 12 and arranged at the bottom, and supports the doctor 13 on one of the side walls.

  The doctor 13 is provided below the developing roller 11 and has a short side along the vertical direction. The material of the doctor 13 is made of a metal such as stainless steel, and is made of a nonmagnetic material or a magnetic material. The doctor support 14 for fixing and supporting the doctor 13 is made of, for example, aluminum and has a hollow rectangular tube shape, and this hollow portion functions as a duct for cooling airflow.

  In the present embodiment, the doctor support 14 is formed in a triangular cylinder shape having a right-angled cross-sectional shape when viewed from the longitudinal direction, and directly supports the doctor 13 and a side wall provided substantially horizontally on the bottom surface of the developing tank 12. The side walls are orthogonal to each other, and the inclined surface is provided inside the developing tank 12 so as to face the developing roller 11 and the second stirring and conveying member 29.

  The main surface 13a of the doctor 13 and the side surface 14a of the doctor support 14 are fixed by a fixing member such as a screw so that the doctor 13 is in close contact therewith. A cover 16 is provided to cover the doctor 13 in parallel along the main surface. The cover 16 is made of a resin such as ABS resin (acrylonitrile-butadiene-styrene copolymer resin) or PS resin (polystyrene resin), and is fixed to a part of the developing tank 12 with screws or the like. A urethane blade 15 for preventing toner scattering from the developing tank 12 to the outside is attached to one end above the cover 16 in the vicinity of the developing roller 11 and the photoreceptor 2 with the same length in the longitudinal direction as the cover. . Note that the cover 16 may be a part of the side wall constituting the developing tank 12 or may be integrally formed as the developing tank 12.

  The doctor 13 and the cover 16 are arranged substantially in parallel with an interval so as to have a predetermined gap. This gap is formed from the vicinity of the layer thickness regulating portion where the doctor 13 is close to the developing roller 11 to the bottom of the developing tank 12.

A through-hole 17 is provided in the side wall of the doctor 13 and the support 14 so as to penetrate both in the thickness direction. As shown in FIG. 2B, the length of the doctor support 14 in the longitudinal direction is the same as the length in the width direction of the developing tank 12 parallel to the axial direction of the developing roller 11, and both ends of the doctor support 14 are connected to the developing tank. The side walls 12a and 12b are fixed with screws or the like. The through hole 17 is
It is a circular hole having an opening diameter of about 5 to 15 mm, and a plurality of openings are provided at a constant interval in the width direction, for example, 10 to 30 mm. Therefore, the gap between the doctor 13 and the cover 16 is communicated with the internal space 14 d of the doctor 13 through the plurality of through holes 17.

  A predetermined position in the image forming apparatus outside the developing tank 12 (for example, the rear frame side, the vicinity of the driving device, etc. In FIG. 2A, the rear side toward the paper surface, and in FIG. 2B, the paper surface. On the right side), a fan 50 for generating a cooling airflow is provided. A first communication pipe 53 extending from the fan 50 to the side wall 12b of the developing tank 12 and a second communication pipe 54 extending from the side wall 12a of the developing tank 12 to an exhaust port (not shown) are provided. On the side walls 12 a and 12 b of the developing tank 12, through holes are formed for communicating the first communication pipe 53 and the second communication pipe 54 with the internal space 14 d of the support 14.

  With such a configuration, when the fan 50 is operated, air is taken into the first communication pipe 53 from the outside, and an airflow in the direction of the arrow 51 from the fan 50 toward the support body 14 is generated inside the first communication pipe 53. As a result, an air flow in the direction of the arrow 52 from the support 14 toward the exhaust port is generated in the second communication pipe 54 through the support 14.

  The doctor 13 is fixed to the side wall of the support 14 so as to be in surface contact. The heat generated in the doctor 13 due to friction or the like moves to the inside of the support 14 through the side wall, and the moved heat is Increase air temperature. Since the air flow as described above is generated inside the support 14, the moved heat is continuously carried out to the outside of the developing tank 12 together with the air whose temperature has increased. Thereby, while the airflow is generated, heat transfer continuously occurs, and the doctor 13 is cooled.

  The support 14 is provided at the bottom of the developing tank 12, and the developer is stored in the developing tank 12 so as to cover the slope of the support 14. Heat transfer from the developer to the inside of the support 14 occurs mainly through the slope portion, and the moved heat increases the temperature of the air. Since the air flow as described above is generated inside the support 14, the moved heat is continuously carried out to the outside of the developing tank 12 together with the air whose temperature has increased. As a result, while the airflow is generated, heat transfer continuously occurs, and the developer is cooled.

  A series of airflows from the fan 50 to the exhaust port generates a negative pressure in the vicinity of the through hole 17 and draws air from the through hole 17 into the support 14. As a result, an air flow from the layer thickness regulating portion to the bottom of the developing tank 12 is generated in the gap between the doctor 13 and the cover 16, and this air current attracts scattered toner on the surface of the developing roller 11.

  In particular, in a high-speed machine, the toner scattering from the surface of the developing roller 11 to the surroundings becomes remarkable as the developing roller 11 rotates at a high speed. In the present invention, the scattered toner 30 is guided to the internal space 14d of the support 14 through the gap and the through hole 17 by the action of the fan 50 and removed, so that the scattered toner contaminates the inside of the apparatus. Is prevented.

FIG. 3 is a schematic diagram showing the configuration of the exhaust port 58. The exhaust port 58 is an opening provided in the exterior 56 of the image forming apparatus 1 and is connected to the second communication pipe 54. Since the air in the second communication pipe 54 contains the collected scattered toner, if the air is exhausted to the outside as it is, the toner will be discharged outside the apparatus. A filter 57 is provided in front of the exhaust port 58 of the second communication pipe 54 so as to block the air flow path. The filter 57 may be a mesh value that does not allow toner to pass through, for example, a filter made of polypropylene and having a weight per unit area of about 70 g / m ² . After the toner is removed by the filter 57, the air 55 is discharged to the outside of the image forming apparatus 1.

FIG. 4 is a diagram illustrating a configuration of an exhaust portion according to another embodiment.
In the present embodiment, only the configuration of the exhaust portion is different, and the other configurations are the same as those of the above-described embodiment. Therefore, only the configuration of the exhaust portion to which the second communication pipe 54 is connected will be described.

  In the present embodiment, the second communication pipe 54 is connected to the toner hopper 60. The air that has passed through the second communication pipe 54 enters the toner hopper 60, and the toner that has moved with the air falls into the toner hopper 60. Thus, it is possible to form more images by mixing the new toner 62 stored in the toner hopper 60 and the toner from which the scattered toner has been collected and recycling it. The airflow into the toner hopper 60 is above the stored toner 62 and along the storage surface 62a of the toner 62, that is, from one side wall of the toner hopper 60 toward the opposite side wall. Configure to flow. With such a configuration, it is possible to prevent the toner 62 from flying up when the airflow directly hits the toner 62.

  The airflow flowing into the toner hopper 60 passes through the filter 61 provided on the side wall on the opposite side of the entering hopper and is exhausted to prevent the toner from leaking from the gap between the containers due to an increase in the air pressure inside the toner hopper 60. Yes.

  The first communication pipe 53 and the second communication pipe 54 are, for example, pipes made of ABS resin or PS resin, and there is no gap with the doctor support 14 while the developing tank 12 is installed in the apparatus. The developer tank 12 is closely attached and has a structure that can be easily detached from the developer tank 12 when the developer tank 12 is taken out of the apparatus.

  As described above, according to the present invention, the doctor support 14 has a duct-like structure, and an air flow is generated therein, whereby the entire support in contact with the developer is cooled, so that the developer can be efficiently cooled. . It is also effective for reducing the size of the developing tank 12. At the same time, the toner scattered in the vicinity of the developing roller 11 can be collected from a position close to the generation source, which is very efficient.

The developing device 10 of the present invention can further have the following structure.
FIG. 5 is a schematic view showing the configuration of the doctor support 14. Fig.5 (a) is the figure which looked at the doctor support body 14 from the side, and FIG.5 (b) is the figure seen from the front.

  Inside the doctor support 14, the toner flows in an air current, but not all of the toner is conveyed, and in reality, some of the toner is deposited on the inner surface of the support 14. It remains attached. If these remain for a long period of time, the air flow and the toner flow are hindered, so it is desirable to periodically clean the inside of the support 14.

  The doctor support 14 has a double structure, and the inner support 14e is detachable by inserting and removing in the longitudinal direction. While the outer support 14f is fixed in the developing tank 12, only the inner support 14e can be removed to the outside of the developing tank 12 through the through hole of the side wall 12a or 12b.

  Thereby, the service person can easily clean the toner adhering to the inner wall surface of the removed inner support 14.

FIG. 6 is a schematic diagram showing the configuration of the doctor 13.
The developing roller 11 is rotatably supported on the rotation shaft with respect to the side walls 12 a and 12 b of the developing tank 12. Therefore, slight gaps 11a and 11b are generated between the sleeve 22 and the side walls 12a and 12b due to the structure. Normally, the gaps 11a and 11b are covered with a sealing member such as PET (polyethylene terephthalate) to prevent the toner from scattering from the inside of the developing tank 12, but in practice, always completely sealed. The actual condition is that more toner scatters through the gaps 11a and 11b at the end than in the central portion of the developing roller 11. Therefore, among the through holes 17 provided in the doctor 13, the opening areas of the holes 17a and 17b at both ends are made larger than the hole 17c at the center. For example, the large diameter is about 1.5 to 2 times the small diameter. By doing so, the toner recovery amount at both ends of the developing roller 11 can be further improved.

  The through hole 17 shown in FIGS. 2B and 6 has a circular opening shape, but of course other shapes may be used, and the hole forming position can be variously changed. .

FIG. 7 is a schematic view showing the configuration and arrangement position of the doctor support 14.
FIG. 7A is an example of a configuration in which the agitating and conveying members 28 and 29 are provided at the bottom of the developing tank 12, and the doctor 13 is provided below the developing roller 11. FIG. 7B is an agitating and conveying member. In this example, one of the reference numerals 26 and 27 is provided above the developing tank 12 and the doctor 13 is provided above the developing roller 11. In the above description, the support body 14 has a triangular cylindrical configuration. However, in the configuration of FIG. 7A, the side wall 14 b that faces the developing roller 11 and the side wall 14 c that faces the stirring and conveying member 29 are formed. A curved surface shape is formed along each outer shape. In the configuration of FIG. 7B, the side wall 14b facing the developing roller 11 and the side wall 14c facing the agitating / conveying member 26 are formed into curved shapes along the respective outer shapes.

  Thus, the side wall of the support 14 is curved along the outer shape of the developing roller and the agitating and conveying member, so that the support 14 can smoothly and stressfully prevent the developer from being conveyed in the developing tank 12. As much as possible, the developer can be transported to the layer thickness regulation position.

FIG. 8 is a schematic diagram showing a configuration of the developing device 10 when the fans 24 and 25 are provided.
A suction fan 24 and a discharge fan 25 are provided at the bottom of both ends in the longitudinal direction of the doctor support 14, and the air 26 sucked from the outside by the fan 24 passes through the support 14 in the longitudinal direction. The air flows into the air 27 discharged by the fan 25.

  The fan may be directly attached to the developing tank 12 when there is a space for providing a fan below the developing tank 12 or when a stronger toner collecting force is required. In addition, although the structure which attaches a fan to the bottom part of the doctor support body 14 was shown, naturally, you may attach to another part and it is possible to increase a quantity.

  In FIG. 2, only the blower fan 50 is shown, but a suction fan may be added to the end of the communication pipe 54.

FIG. 9 is a diagram illustrating attachment of the doctor 13 to the support 14.
The doctor 13 is fixed to the side wall of the doctor support 14 with screws 18. Therefore, the doctor 13 is provided with a through-hole through which the screw 18 passes, and a tap (female screw) is cut on the side wall of the doctor support 14. The thickness t of the side wall t of the doctor support 14 is required to be at least as large as the thickness of the doctor in consideration of the tap length necessary for screwing and sufficient attachment strength so that the doctor 13 is not deformed.

(Example)
The photograph shown in FIG. 10 is a result of confirming through experiments that the support 14 was produced and the toner was actually sucked. From the surface of the doctor 13 toward the through hole 17, a sucked toner mark 30 is seen.

Further, the cooling effect of the developer by the support 14 was about −2 ° C. as compared with the comparative example in which the support 14 was not provided.
Developing roller: 18mm outer diameter, 427mm / s rotation speed
Doctor: Non-magnetic stainless steel plate thickness 1mm
Doctor gap; 0.4mm
Doctor support plate: Aluminum, standard thickness 2mm, total length 331mm
Fan flow rate; 0.015 m ³ / min

  FIG. 11 is a graph showing the cooling effect of the support 14. The horizontal axis indicates the number of printed sheets [sheets], the left vertical axis indicates the image density ID [−], and the right vertical axis indicates the developer temperature [° C.] in the vicinity of the support 14.

  In the experiment, after continuously printing 3k sheets (k is 1000) without cooling (fan 50 stopped, no airflow generated), printing was stopped and cooling was performed for about 2 hours.

  As shown in the graph. The developer temperature gradually increased from about 25 ° C. at room temperature to 37 ° C. until the number of printed sheets was 3k. Along with this, the initial image density was close to 1.8 but decreased to 1.3. Then, after printing 3k sheets, the developer temperature could be lowered to 22 ° C. by cooling, and the image density returned to 1.8 again.

  The image subjected to the image density measurement is a solid image, measured with a spectrocolorimetric densitometer Model 939 manufactured by X-Rite, and a developer temperature of midi LOGGER TYPE GL450 (K type thermocouple) manufactured by GRAPHTEC. It measured using.

  As the developer temperature rises, the toner particles soften and the toner particles and the toner particles, or the toner particles and the carrier particles cause a light fusion, so this adhesion force is superior to the electrostatic force of the photosensitive drum. It is considered that development on the photosensitive drum is difficult to occur, and as a result, the print density is lowered.

  Thus, it can be seen that cooling the developer is important for maintaining the characteristics of the developer.

1 is a diagram showing a simplified configuration of an image forming unit portion of an image forming apparatus 1 including a developing device 10 according to an embodiment of the present invention. 2 is a schematic view showing a structure of a doctor support 14. FIG. 3 is a schematic view showing the configuration of an exhaust port 58. FIG. It is a figure which shows the structure of the exhaust part of other embodiment. 3 is a schematic view showing a configuration of a doctor support 14. FIG. 2 is a schematic diagram illustrating a configuration of a doctor 13. FIG. It is the schematic which shows the structure and arrangement position of the doctor support body. FIG. 2 is a schematic diagram illustrating a configuration of the developing device 10 when fans 24 and 25 are provided. It is a figure explaining attachment to the support body 14 of the doctor 13. FIG. It is a figure which shows the doctor 13 and the support body 14 of an Example. It is a graph which shows the cooling effect by the support body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photoconductor 3 Charging apparatus 4 Exposure apparatus 5 Transfer apparatus 6 Cleaning apparatus 10 Developing apparatus 11 Developing roller 12 Developing tank 13 Doctor blade 14 Doctor support body 50 Fan

Claims (9)

Provided in an image forming apparatus that forms an image using an electrophotographic system, and a developer carrier that is rotatably provided to carry a developer, and a developer carrier that is attached to the support and has a developer on the developer carrier. In the developing device provided with a layer thickness regulating member for regulating the layer thickness inside the developing tank,
The support has a space inside, is provided at the bottom of the developing tank, and supports the layer thickness regulating member in surface contact with the side wall,
A developing device, further comprising an airflow generating means for generating an airflow from the outside of the developing tank to the outside of the developing tank through the internal space of the support. A through hole is provided that penetrates the layer thickness regulating member and the side wall supporting the layer thickness regulating member to the internal space of the support,
A cover member provided at a predetermined interval from the layer thickness regulating member;
A gap is formed between the cover member and the layer thickness regulating member from the layer thickness regulating position by the layer thickness regulating member to the bottom of the developing tank,
The developing device according to claim 1, wherein the gap and the internal space of the support are communicated with each other through the through hole.   A plurality of the through holes are provided, and among the plurality of through holes, the opening diameters of the through holes provided at both ends in the longitudinal direction of the support are larger than the opening diameters of the other through holes. The developing device according to claim 2. A storage container for storing new toner to be replenished into the developing tank;
The developing device according to claim 1, wherein the air flow generation unit introduces an air flow toward the outside of the developing tank into the storage container.   The support body has a double structure, and the inner support body is configured to be detachable in the longitudinal direction with respect to the outer support body. The developing device described.   The side wall close to the developer stirring member among the side walls of the support has a curved surface shape along the outer shape of the developer stirring member. Development device.   The side wall close to the developer carrier among the side walls of the support has a curved shape along the outer shape of the developer carrier. Development device.   8. The development according to claim 1, wherein the thickness of the side wall of the support that fixes and supports the layer thickness regulating member is equal to or greater than the thickness of the layer thickness regulating member. apparatus.   An image forming apparatus comprising the developing device according to claim 1.