JP2009288708A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, effectively suppressing temperature rise of toner caused by friction with a stirring and conveying member (spiral feeder) in a housing. <P>SOLUTION: The developing device includes the housing 21, inside which a developing roller 22 supplying the toner T to the peripheral surface of a predetermined photoreceptor drum 131, while rotating about a shaft center is attached, and the spiral feeder 30 which is rotatably laid between side plates 213 in the housing 21 about the shaft center, and feeds the toner T to the peripheral surface of the developing roller 22, by rotating about the shaft center. The spiral feeder 30 has a shaft 31, made of metal, and a spiral fin (stirring and conveying blade) 32 made of synthetic resin, which is fit externally to the shaft 31 to rotate integrally. The spiral fin 32 is provided with an exposing aperture 323, through which a part of the shaft 31 is exposed to the outside, and the end of the shaft 31 or a part connected to the end is exposed to the outside from the housing 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device applied to an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  Conventionally, a developing device as described in Patent Document 1 is known. This developing device is applied to an image forming apparatus such as a copying machine or a printer. Toner is applied to the surface of an image carrier (photosensitive drum in Patent Document 1) incorporated in the main body of the image forming apparatus. Then, a toner image is formed along the electrostatic latent image on the surface of the image carrier.

  Such a developing device has a box shape and has an opening on one side surface that faces the surface of the image carrier, and is loaded with a developer, is housed in the housing, and contains the developer. A screw (agitating and conveying member) that circulates and conveys within the casing while stirring, and a developing sleeve that supplies the developer being conveyed by the screw to the surface of the image carrier through the opening are provided.

  The opening is provided with a developer regulating member whose leading edge extends over substantially the entire length of the developing sleeve facing the peripheral surface of the developing sleeve. Then, the developer supplied to the image carrier by the rotation of the developing sleeve passes through the gap between the developer regulating member and the peripheral surface of the developing sleeve, and is cut out by being regulated to a predetermined layer thickness. It is supplied to the peripheral surface of the body drum.

  By the way, in such a developing device, the toner receives resistance when passing through the gap between the peripheral surface of the developing sleeve and the developer regulating member due to the driving rotation around the cylindrical center of the developing sleeve, and this resistance causes Although the temperature rises due to the frictional force, the developer quality may be deteriorated by this temperature rise. When the toner deteriorates, there arises a problem that an appropriate toner image cannot be formed on the peripheral surface of the photosensitive drum.

In order to eliminate such inconvenience, in the invention of Patent Document 1, the regulating member is made of a metal hollow product, and a cooling liquid or gas is circulated through the hollow portion. In this way, even if frictional heat is generated in the toner passing through the gap between the developing sleeve and the developer regulating member, the cooling temperature is supplied from the developer regulating member toward the toner, so the temperature of the toner rises. It is prevented.
JP 2004-109868 A

  However, in the developing device described in Patent Document 1, only the toner that passes through the gap between the developing sleeve and the developer regulating member is subjected to the cooling process, and therefore the toner is contained in the housing. In order to suppress the increase in the temperature of the toner due to frictional heat when circulating and transporting the toner, there is a problem that the toner in the housing cannot be effectively cooled as a result. .

  The present invention has been made to solve the conventional problems, and provides a developing device capable of effectively suppressing the temperature rise of the toner due to friction with the agitating / conveying member in the casing. It is aimed.

  According to the first aspect of the present invention, there is provided a predetermined case, a developing roller that supplies toner to the surface of the predetermined image carrier while rotating around the axis inside the case, and an opposing wall surface in the case. And an agitating / conveying member that stirs the toner by rotating around the axial center, and the agitating / conveying member rotates integrally with the metal shaft and the shaft. An agitating / conveying blade made of synthetic resin that can be externally fitted, and the agitating / conveying blade is provided with an exposure opening that exposes a part of the shaft into the housing, and the shaft end or the end The developing device is characterized in that a portion connected to the portion is exposed to the outside from the housing.

  According to this configuration, the toner in the housing is sent toward the developing roller for the development processing on the surface of the image carrier by rotating the stirring and conveying member around the axis. Then, the frictional heat generated by the friction between the stirring and conveying member rotating at this time and the toner is exposed to the space in the housing through the exposure opening formed between the stirring and conveying blades made of synthetic resin, And it is transmitted to the metal shaft in contact with the toner, and the heat is dissipated through the end portion of this shaft or a portion connected to the end portion and exposed to the outside from the housing.

  In this way, the stirring and conveying member is constituted by a metal shaft and a synthetic resin stirring and conveying blade fitted on the shaft, and an exposure opening that exposes a part of the shaft to the stirring and conveying blade. Thus, it is possible to efficiently dissipate frictional heat through a metal shaft having excellent thermal conductivity while ensuring the ease of manufacturing a complicated shape of the stirring and conveying blade.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, a blower mechanism is provided for blowing an air flow to a portion of the stirring and conveying member exposed to the outside from the casing. It is.

  According to this configuration, the agitation transport member is more effectively cooled by heat exchange with the air flow by blowing an air flow to the portion exposed to the outside from the casing of the agitation transport member via the air blowing mechanism. As a result, the temperature rise of the toner is more effectively suppressed.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the portion connected to the shaft end is a driving force transmission gear.

  According to such a configuration, the gear is suitable as a member for heat dissipation because a large number of gear teeth are formed on the peripheral surface thereof, thereby increasing the surface area.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the air blowing mechanism includes a fan device that takes in outside air, a duct that guides the outside air taken in by the fan device to the end side of the shaft, and the duct. And a nozzle portion that is connected to the downstream end of the nozzle and blows outside air onto the gear.

  According to such a configuration, the outside air taken in by the fan device is guided to the end portion of the shaft through the duct, and subsequently blown to the gear via the nozzle portion connected to the downstream end of the duct. Heat exchange with the outside air is intensively performed and cooling is effectively performed.

  According to the developing device of the present invention, the agitating / conveying member is constituted by a metal shaft and a synthetic resin agitating / conveying blade fitted on the shaft, and a part of the shaft is provided on the agitating / conveying blade. By providing an exposed opening that is exposed to the outside, it is possible to efficiently dissipate frictional heat through a metal shaft with excellent thermal conductivity, while ensuring the ease of manufacturing a complicatedly shaped stirring and conveying blade. Can do. Therefore, it is possible to effectively prevent the occurrence of inconvenience that the temperature of the toner rises due to friction with the agitating / conveying member in the developing device, which causes the toner to deteriorate or cannot be properly developed. it can.

  In particular, by blowing an air flow to a portion exposed to the outside from the casing of the agitating and conveying member, it is possible to more effectively suppress an increase in toner temperature by heat exchange with the air flow.

  FIG. 1 is a cross-sectional view illustrating an embodiment of the internal structure of a printer to which a developing device according to the present invention is applied. As shown in FIG. 1, a printer (image forming apparatus) 10 includes a sheet storage unit 12 that stores sheets P to be subjected to a printing process, and one sheet fed from a sheet bundle P1 stored in the sheet storage unit 12. An image forming unit 13 that performs an image forming process on the sheet P, and a fixing unit 14 that performs a fixing process on the toner image on the sheet P onto which the toner image has been transferred as a result of the image forming process. Are built in the apparatus main body 11 and have a basic configuration in which a paper discharge section 15 for discharging the paper P subjected to fixing processing by the fixing section 14 is provided at the top of the apparatus main body 11.

  A predetermined number (one in this embodiment) of paper cassettes 121 is provided in the paper storage unit 12 so as to be detachable from the apparatus main body 11. A pickup roller 122 is provided at the upstream end (right side in FIG. 1) of the paper cassette 121 to feed out the paper P one by one from the paper bundle P1. The paper P fed out of the paper cassette 121 by driving the pickup roller 122 is supplied to the image forming unit 13 through the paper feed conveyance path 123 and the registration roller pair 124 provided at the downstream end of the paper feed conveyance path 123. Paper.

  The image forming section 13 performs a transfer process on the paper P after performing a predetermined image forming process based on image information transmitted from a computer or the like. The image forming unit 13 is charged in a clockwise direction from a position immediately above the photoconductive drum 131 so as to follow a peripheral surface of the photoconductive drum (image carrier) 131 provided in a substantially central portion of the apparatus main body 11. A roller 132, an exposure device 134, a developing device 20, a transfer roller 133, and a cleaning device 135 are provided.

  The photosensitive drum 131 is for forming a toner image along the electrostatic latent image after forming the electrostatic latent image on the peripheral surface. The photosensitive drum 131 is coaxially and integrally supported by a drum shaft 131a extending in the front-rear direction (a direction orthogonal to the paper surface of FIG. 1) at a substantially central portion of the apparatus main body 11, and is driven by a driving means (not shown). The drum shaft 131a rotates integrally with the drum shaft 131a by the drive rotation of the drum shaft 131a toward the clockwise direction.

  The charging roller 132 forms a uniform charge on the peripheral surface of the photosensitive drum 131 rotating clockwise around the drum shaft 131 a, and the peripheral surface abuts on the peripheral surface of the photosensitive drum 131. While being rotated, the photosensitive drum 131 is charged. Instead of the charging roller 132, a corona discharge type that applies a charge to the peripheral surface of the photosensitive drum 131 by corona discharge from a wire may be employed.

  The exposure device 134 irradiates the peripheral surface of the rotating photosensitive drum 131 with laser light based on image data transmitted from an external device such as a computer. An electrostatic latent image is formed on the peripheral surface of the photoconductive drum 131 by erasing the electric charge of the portion irradiated with the laser beam.

  The developing device 20 attaches the toner T to a portion where an electrostatic latent image is formed on the peripheral surface by supplying toner T (depicted in FIG. 2 as a dotted line) as a developer to the peripheral surface of the photosensitive drum 131. As a result, a toner image is formed on the peripheral surface of the photosensitive drum 131. In this embodiment, a so-called magnetic one-component system consisting of only magnetic toner is used as a developer. A so-called two-component system composed of a toner and a magnetic carrier can also be used.

  Incidentally, the toner T is a fine powder having a volume average particle diameter of 6 to 12 μm in which additives such as a colorant, a charge control agent and wax are dispersed in a binder resin. Magnetic powders such as ferrite and magnetite having an average particle diameter of 0.01 to 0.50 μm are externally added thereto. In particular, organic substances such as wax are often deteriorated due to an increase in temperature, and due to this, the toner T deteriorates and proper image forming processing may not be performed. This is the reason why the present invention was proposed.

  The toner T is appropriately supplied to the developing device 20 from a toner cartridge 29 that is detachably attached to the developing device 20.

  The transfer roller 133 electrostatically transfers the charged toner image formed on the peripheral surface of the photosensitive drum 131 to the paper P with respect to the paper P sent to a position immediately below the photosensitive drum 131. is there.

  The cleaning device 135 is for removing and cleaning the toner T remaining on the peripheral surface of the photosensitive drum 131 after the transfer process. The peripheral surface of the photoconductive drum 131 cleaned by the cleaning device 135 goes to the charging roller 132 again for the next image forming process.

  The fixing unit 14 performs a fixing process by heating the toner image of the paper P that has been transferred by the image forming unit 13. The fixing unit 14 includes a heat roller 141 in which an energization heating element such as a halogen lamp is mounted, and a pressure roller 142 whose peripheral surface is opposed to the lower portion of the heat roller 141.

  Then, the paper P after the transfer process is composed of a heat roller 141 that is driven to rotate clockwise around the roller center, and a pressure roller 142 that is driven to rotate counterclockwise around the roller center. By passing through the nip portion between them, heat from the heat roller 141 is obtained and the fixing process is performed. The paper P subjected to the fixing process is discharged to the paper discharge unit 15 through the paper discharge conveyance path 143.

  The paper discharge unit 15 is formed by recessing the top of the apparatus main body 11, and a paper discharge tray 151 for receiving the discharged paper P is formed at the bottom of the concave portion.

  2 is a partially cut perspective view of the developing device 20 as viewed from the front right side, and FIG. 3 is a perspective view of the developing device 20 shown in FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2 to 4, the XX direction is referred to as the left-right direction, and the Y-Y direction is referred to as the front-rear direction. In particular, the -X direction is leftward, the + X direction is rightward, the -Y direction is forward, and the + Y direction is forward. It is called the back.

  As shown in FIGS. 2 and 4, the developing device 20 includes a developing roller 22 that supplies toner T to the peripheral surface of the photosensitive drum 131 in a housing 21 having an irregular box shape, and the developing roller 22. And a spiral feeder (agitating and conveying member) 30 for conveying the toner T replenished from the toner cartridge 29 toward the circumferential surface of the developing roller 22 while agitating the blade. A blower mechanism 40 that cools the toner T inside through a spiral feeder 30 and a driving mechanism 50 that provides driving force to the developing roller 22 and the spiral feeder 30 are provided outside the casing 21. ing.

  The spiral feeder 30 includes a first spiral feeder 30a disposed at a right position in the casing 21, and a second spiral feeder 30b that conveys toner transferred from the first spiral feeder 30a rearward. It is made up of. The toner T is supplied to the peripheral surface of the developing roller 22 that is partially rotated while being conveyed by the second spiral feeder 30b. The remaining portion of the toner T is returned to the first spiral feeder 30a and circulated between the first and second spiral feeders 30a and 30b. The toner T supplied to the peripheral surface of the developing roller 22 is supplied to the latent image region on the peripheral surface of the photosensitive drum 131 by the rotation of the developing roller 22, and thereby the electrostatic latent image on the peripheral surface of the photosensitive drum 131. A toner image along the line is formed.

  As shown in FIGS. 2 and 4, the casing 21 has a bowl shape when viewed from the front (−Y direction), and is tilted leftward from a substantially central position in the left-right direction. A bottom plate 211 whose portion faces the photosensitive drum 131, a top plate 212 disposed on the top so as to face the bottom plate 211, and a pair of front and rear side plates provided between the bottom plate 211 and the front and rear ends of the top plate 212. 213 (the front side plate is indicated by a two-dot chain line in FIG. 2) and a toner receiving tray 214 provided between the pair of side plates 213 at a position slightly above the bottom plate 211.

  The top plate 212 is formed in a stepped shape with one step higher on the left side. The lower top plate 212a on the right side, the higher top plate 212b on the left side, and the left edge of the lower top plate 212a and the higher top plate. It consists of a vertical top plate 212c installed between the right end edge of the plate 212b. A toner receiving port 212d for receiving toner from the toner cartridge 29 is provided at the rear end of the lower top plate 212a. Further, between the left end edge of the high top plate 212 b and the left end edge of the bottom plate 211, the toner T in the housing 21 is separated from the peripheral surface of the photosensitive drum 131 so as to face the peripheral surface of the photosensitive drum 131. A toner supply port 216 for supplying the toner is opened.

  The toner receiving tray 214 includes a first tray 214a that accommodates the first spiral feeder 30a, a second tray 214b that accommodates the second spiral feeder 30b, and a third tray 214c that is disposed below the developing roller 22 at a lower portion. It has. The first to third trays 214a, 214b, and 214c each have a circular arc shape with a concave top surface when viewed from the front so as to correspond to the corresponding first and second spiral feeders 30a and 30b and the developing roller 22. Is formed. Further, a right side wall 217 is provided at the right end of the first tray 214a, and the right side in the casing 21 is closed by the right side wall 217 being installed between the right ends of the bottom plate 211 and the lower top plate 212a. ing. The left end edge of the third tray 214c is integrally connected to the bottom plate 211 over the entire length extending in the front-rear direction, whereby the left portion of the space surrounded by the bottom plate 211 and the toner receiving tray 214 is closed to the outside. It is in a state.

  A partition wall 215 is provided between the first and second trays 214a and 214b. A front flow port 215a (FIG. 2) is opened at the front position of the partition wall 215, and a rear flow port 215b (FIG. 2) is opened at the rear position. The toner T introduced into the housing 21 from the toner cartridge 29 via the toner receiving port 212d is first transported forward in the first tray 214a by the driving rotation of the first spiral feeder 30a, and flows forward. It is carried into the second tray 214b through the opening 215a, is conveyed backward in the second tray 214b by the driving rotation of the second spiral feeder 30b, and thereafter circulates between the first and second trays 214a and 214b. However, a part is supplied to the developing roller 22.

  The developing roller 22 includes a roller shaft 221 penetrating between a pair of side plates 213, a cylindrical roller body 222 concentric with the roller shaft 221, an inner body of the roller body 222, and the roller shaft 221. It consists of a fixed in-roller magnet 223. The roller body 222 rotates relative to the roller shaft 221, whereas the roller shaft 221 is fixed at an appropriate position of the casing 21 of the developing device 20 so as not to rotate.

  The developing roller 22 is installed at a position above the third tray 214c so that the circumferential surface of the roller body 222 faces the circumferential surface of the photosensitive drum 131 through the toner supply port 216. Then, the driving force of a driving motor 511 provided at an appropriate position in the apparatus main body 11 is transmitted to the roller main body 222 via a predetermined gear mechanism (a driving gear 512 and an input gear 513 to be described later). , The roller shaft 221 rotates counterclockwise in FIG. Part of the toner T being circulated and conveyed by the second spiral feeder 30 b on the third tray 214 c by the rotation of the roller body 222 is supplied to the peripheral surface of the developing roller 22.

  FIG. 5 is a perspective view showing an embodiment of the spiral feeder 30. FIG. 5 (A) is an exploded perspective view, and FIG. 5 (B) is an assembled perspective view. In addition, the direction display by X and Y in FIG. 5 is the same as in FIG. 2 (−X: leftward, + X: rightward, −Y: forward, + Y: backward). 5, the first spiral feeder 30a is shown as an example of the spiral feeder 30, but the first and second spiral feeders 30a and 30b are spiral directions of the spiral fins (stirring conveying blades) 32. Is the reverse, and the basic configuration is the same.

  As shown in FIG. 5, the spiral feeder 30 includes a metal shaft 31 and a synthetic resin spiral fin 32 through which the shaft 31 is inserted over the entire length in the longitudinal direction.

  The length of the shaft 31 is set so that it can be passed through between the pair of side plates 213 of the housing 21. A small-diameter shaft 311 is provided at the rear end of the shaft 31 so as to project concentrically. A pair of key protrusions 312 are provided at the base portion of the small-diameter shaft 311 so as to protrude in directions opposite to each other in the radial direction. These key projections 312 are concentric with gears described later (a first feeder gear 525 when the spiral feeder 30 is the first spiral feeder 30a, and a second feeder gear 523 when the spiral feeder 30 is the second spiral feeder 30b). So that the gear and the shaft 31 can rotate integrally around the axis.

  The spiral fin 32 includes a pair of fin bodies 321 concentrically entangled with each other by 180 ° when viewed from the end surface, and a plurality of connecting cylinders 322 interposed between the pair of fin bodies 321. ing. In the present embodiment, the connecting cylindrical body 322 is provided at three locations, both ends and the central portion of the fin main body 321. The connecting cylinder 322 has an inner diameter dimension slightly larger than the outer diameter dimension of the shaft 31. An exposure opening 323 for exposing the shaft 31 to the outside is formed between the pair of fin main bodies 321.

  Each connecting cylinder 322 has a locking hole 324 drilled in a direction perpendicular to the cylinder center direction, and the shaft 31 corresponds to each locking hole 324. Through-holes 313 are provided at the positions where the holes penetrate in the direction perpendicular to the axial direction.

  Then, as indicated by arrows in FIG. 5A, the shaft 31 is inserted into the plurality of connecting cylinders 322, and each of the through holes 313 is opposed to the corresponding locking hole 324. As shown in FIG. 5B, the shaft 31 has a pair of fin main bodies 321 by inserting the locking pins 33 into the holes 324 and the through-holes 313 and fastening the both ends of the locking pins 33 respectively. It will be installed in between.

  Since the peripheral surface of the shaft 31 is exposed to the outside through the exposure opening 323 in a state where the shaft 31 is mounted on the spiral fin 32, the toner T in the housing 21 always has the exposure opening 323. Via the shaft 31.

  Accordingly, the frictional heat generated between the spiral feeder 30 and the toner T due to the rotation of the spiral feeder 30 is transferred to the outside of the housing 21 through the metal shaft 31 having a high thermal conductivity, and the end of the shaft 31 is transferred. Heat is radiated from the part. As a result, it is possible to effectively prevent the occurrence of inconvenience that the toner T is deteriorated due to the frictional heat and becomes abnormally high, or an appropriate toner image is not formed on the peripheral surface of the photosensitive drum 131.

  FIG. 6 is a perspective view for explaining an embodiment of the air blowing mechanism 40 and the driving mechanism 50 of the developing device 20. The direction display by X and Y in FIG. 6 is the same as in FIG. 2 (X is the left-right direction (−X: leftward, + X: rightward), Y is the front-back direction (−Y: forward, + Y: backward). )). In FIG. 6, the casing 21 is not shown in order to avoid complication.

  First, the drive mechanism 50 will be described. The driving mechanism 50 includes a driving force input unit 51 for inputting a driving force to the developing roller 22 and a driving force output unit that outputs the driving force input from the driving force input unit 51 toward the spiral feeder 30. 52.

  The driving force input unit 51 includes a driving motor 511 provided in the lower front portion of the developing roller 22 in the apparatus main body 11, and a driving gear 512 that is concentrically mounted on a driving shaft 511a of the driving motor 511 so as to be integrally rotatable. And an input gear 513 concentrically connected to the front end portion of the roller body 222 of the developing roller 22 so as to be integrally rotatable, and meshed with the drive gear 512.

  The driving force output unit 52 includes an output gear 521 concentrically connected to the rear end portion of the roller body 222 and a second idle gear meshing with the output gear 521 obliquely downward to the right of the output gear 521. A second idle gear 522 that can rotate about the shaft 522a, and a second feeder gear 523 that meshes with the second idle gear 522 and is externally fitted to the shaft 31 of the second spiral feeder 30b so as to be concentrically and integrally rotatable. A first idle gear 524 that can rotate about a first idle shaft 524a meshing with the second feeder gear 523 under the second feeder gear 523 diagonally to the right, and meshing with the first idle gear 524, and And a first feeder gear 525 that is concentrically and externally fitted to the shaft 31 of the first spiral feeder 30a.

  According to the drive mechanism 50 having such a configuration, when the drive motor 511 is driven in the clockwise direction when viewed from the front side in FIG. 6, the drive force is input via the drive shaft 511 a and the drive gear 512 to the input gear 513. Is transmitted in the counterclockwise direction around the roller shaft 221, whereby the roller body 222 rotates around the roller shaft 221 in the counterclockwise direction. By this rotation, the toner T (indicated by a white arrow in FIG. 6) in the housing 21 is pumped up by the peripheral surface of the roller body 222 and supplied to the photosensitive drum 131 via the blade 23.

  Then, the counterclockwise rotation of the roller body 222 around the roller shaft 221 is transmitted to the second feeder gear 523 via the output gear 521 and the second idle gear 522 on the driving force output section 52 side. The fin body 321 of the second spiral feeder 30b rotates integrally around the shaft 31 counterclockwise by the integral rotation of the two feeder gear 523 around the shaft 31 counterclockwise.

  The rotation of the fin body 321 causes the toner T on the second tray 214b (FIG. 2) in the casing 21 to be conveyed rearward as indicated by a white arrow pointing backward in FIG. A part is pumped up by the rotation of the developing roller 22 and supplied to the photosensitive drum 131. The remainder of the toner T is introduced into the first tray 214a through the rear circulation port 215b provided at the rear end of the second tray 214b.

  Further, the counterclockwise rotation of the second feeder gear 523 is transmitted to the first feeder gear 525 via the first idle gear 524, and the first spiral feeder 525 is rotated counterclockwise by the rotation of the first feeder gear 525. 30a spiral fin 32 rotates integrally counterclockwise.

  Then, the toner T on the first tray 214a (FIG. 2) in the casing 21 is indicated by a white arrow pointing forward in FIG. 6 due to the counterclockwise rotation of the spiral fin 32 to the first spiral feeder 30a. Thus, it is conveyed toward the front. The toner T conveyed toward the front is introduced into the second tray 214b through the front circulation port 215a at the front end of the first tray 214a.

  As described above, when both the first and second spiral feeders 30a and 30b are rotated counterclockwise, the toner T in the casing 21 circulates in the casing 21 in the clockwise direction in plan view. Will be transported.

  Next, the blower mechanism 40 will be described with reference to FIG. 7 and FIG. 6 referred to in the description of the drive mechanism 50 earlier with reference to other drawings as necessary. 7 is a view taken along line VII in FIG. The direction display by X in FIG. 7 is the same as in FIG. 6 (−X: leftward, + X: rightward), but the actual left and right sides of the paper of FIG. It has become.

  The air blowing mechanism 40 includes a fan device 41 that is provided at an appropriate position in the apparatus main body 11 and sucks outside air to blow, a flat duct 42 that guides air from the fan device 41, and a downstream end of the flat duct 42. And a nozzle portion 43 connected to the. A communication opening 421 (FIGS. 4 and 7) for supplying the airflow from the flat duct 42 to the nozzle portion 43 is provided at the lower right side of the rear side plate 213.

  As shown in FIG. 2, the flat duct 42 is formed to include a space surrounded by a bottom plate 211 of the casing 21 of the developing device 20, a toner receiving tray 214, and a right side wall 217. It is formed flat. Therefore, the outside air sent from the fan device 41 can come into contact with the lower surface of the toner receiving tray 214 over a wide range, whereby the outside air and the toner T on the toner receiving tray 214 efficiently exchange heat. As a result, the cooling effect of the toner T in the developing device 20 can be improved.

  As shown in FIGS. 3 and 4, the nozzle portion 43 includes a rectangular tube-shaped nozzle body 431 whose right end is connected to the rear end of the flat duct 42 and a top plate 432 of the nozzle body 431 in the horizontal direction. And a plurality of nozzle holes 433 arranged in series toward the head. The nozzle portion 43 is provided at a position facing the first and second feeder gears 525 and 523 below the first and second feeder gears 525 and 523.

  According to the air blowing mechanism 40, the air sucked by driving the fan device 41 passes through the flat duct 42 and is supplied to the nozzle portion 43 through the communication opening 421. Since the first and second feeder gears 525 and 523 having a large surface area are blown to the first and second feeder gears 525 and 523, the first and second feeder gears 525 and 523 are effectively cooled by heat exchange with the blown air.

  Therefore, the peripheral surface of the shaft 31 exposed into the casing 21 through the exposed opening 323 of the fin body 321 of the spiral fin 32 is transferred from the toner T whose temperature has been increased by frictional heat, but is cooled. Since heat is effectively transferred toward the first and second feeder gears 525 and 523 due to a large temperature gradient between the first and second feeder gears 525 and 523, the toner T becomes high temperature due to frictional heat as a result. Can be effectively prevented.

  As described above in detail, the developing device 20 according to this embodiment is equipped with the developing roller 22 that supplies the toner T toward the peripheral surface of the predetermined photosensitive drum 131 while rotating about the axis. A casing 21 and a spiral feeder 30 provided between the side plate 213 in the casing 21 so as to be rotatable around an axis and sending toner T to the peripheral surface of the developing roller 22 by rotating around the axis. The spiral feeder 30 includes a metal shaft 31 and a synthetic resin spiral fin 32 that is externally fitted to the shaft 31 so as to be integrally rotatable.

  The spiral fin 32 is provided with an exposure opening 323 that exposes a part of the shaft 31 to the space in the housing 21, and an end portion of the shaft 31 or a portion connected to the end portion is exposed to the outside from the housing 21. ing.

  According to such a configuration, the toner T in the housing 21 is sent toward the developing roller 22 for development processing on the surface of the photosensitive drum 131 by rotating the spiral feeder 30 around the axis. The frictional heat generated by the friction between the rotating spiral feeder 30 and the toner T at this time is exposed to the metal through the exposed openings 323 formed between the synthetic resin spiral fins 32. Is transmitted to the shaft 31 and is connected to the end of the shaft 31 or connected to the end of the shaft 31 (the first and second feeder gears 525 and 523 at the home position). Heat is dissipated.

  As described above, the spiral feeder 30 is constituted by the metal shaft 31 and the synthetic resin spiral fin 32 that is externally fitted to the shaft 31, and a part of the shaft 31 is exposed to the spiral fin 32. By providing the exposed opening 323, it is possible to efficiently dissipate the frictional heat through the metal shaft 31 having excellent thermal conductivity while ensuring the ease of manufacturing the spiral fin 32 having a complicated shape. it can.

  Accordingly, the temperature of the toner T rises due to friction with the spiral feeder 30 in the developing device, thereby effectively preventing the occurrence of inconveniences such as deterioration of the toner T or inability to perform proper development processing. be able to.

  In particular, by blowing an air flow to a portion exposed to the outside from the casing 21 of the spiral feeder 30, an increase in the temperature of the toner T can be more effectively suppressed by heat exchange with the air flow. .

  In addition, since the driving force transmission gears (in this embodiment, the first and second feeder gears 525 and 523) are employed as the portion to which the air flow connected to the end portion of the shaft 31 is blown, Many gear teeth are formed on the surface, and the surface area is very large, so that heat can be radiated more effectively.

  Further, since the air sent through the flat duct 42 by the driving of the fan device 41 is blown to the first and second feeder gears 525 and 523 through the nozzle portion 43, the first and second feeder gears 525 are provided. The cooling process of the toner T via the shaft 523 and the shaft 31 can be performed more effectively.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, the printer 10 is described as an example of the image forming apparatus to which the developing device 20 is applied. However, the present invention is limited to the printer 10 as the image forming apparatus. Instead, it may be a copying machine or a facsimile machine.

  (2) In the above-described embodiment, a both-side separation type in which the toner T is replenished from the toner cartridge 29 that is detachably mounted to the developing device 20 is applied. A so-called developing unit in which the toner cartridge 29 is integrated with the housing 21 of the developing device 20 from the beginning may be adopted.

  (3) In the above embodiment, the first and second feeder gears 525 and 523 are supplied from the nozzle hole 433 of the nozzle portion 43 to the air sent to the nozzle portion 43 through the flat duct 42 by driving the fan device 41. However, when it is difficult to blow air to the first and second feeder gears 525 and 523 due to layout restrictions, the first and second feeder gears 525 and 523 of the shaft 31 are provided. You may make it blow air on the edge part on the opposite side to the side which exists. In this case, providing a metal member having a large surface area such as attaching a metal disk to the opposite end of the shaft 31 is effective in improving the cooling effect.

  (4) In the above embodiment, the spiral feeder 30 is assembled with the shaft 31 and the spiral fin 32. However, the exposed opening 323 for exposing the shaft 31 is formed to integrate the spiral fin 32 made of synthetic resin. You may shape | mold.

It is explanatory drawing of the cross sectional view which shows one Embodiment of the internal structure of the printer with which the image development apparatus concerning this invention was applied. It is a partially cut perspective view showing an embodiment of a developing device. FIG. 3 is a perspective view of the developing device shown in FIG. 2 as viewed from the rear right side. FIG. 4 is a sectional view taken along line IV-IV of the developing device shown in FIG. 2. It is a perspective view which shows one Embodiment of a spiral feeder, (A) is a disassembled perspective view, (B) is an assembly perspective view. It is a perspective view for explaining one embodiment of a blower mechanism and a drive mechanism of the developing device. It is a VII line arrow directional view of FIG.

Explanation of symbols

10 Printer (image forming device)
DESCRIPTION OF SYMBOLS 11 Apparatus main body 12 Paper storage part 121 Paper cassette 122 Pickup roller 123 Paper feed conveyance path 124 Registration roller pair 13 Image formation part 131 Photosensitive drum (image carrier)
131a drum shaft 132 charging roller 133 transfer roller 134 exposure device 135 cleaning device 14 fixing unit 141 heat roller 142 pressure roller 143 paper discharge conveyance path 15 paper discharge unit 151 paper discharge tray 20 developing device 21 case 211 bottom plate 212 top plate 212a Lower ceiling 212b Higher ceiling 212c Vertical ceiling 212d Toner receiving port 213 Side plate 214 Toner receiving tray 214a First tray 214b Second tray 214c Third tray 215 Partition wall 215a Front distribution port 216 Rear distribution port 216 Toner supply port 217 Right side Wall 22 Developing roller 221 Roller shaft 222 Roller body 223 Magnet in roller 23 Blade 29 Toner cartridge 30 Spiral feeder (stirring conveying member)
30a First spiral feeder (stirring conveying member)
30b Second spiral feeder (stirring conveying member)
31 Shaft 311 Small-diameter shaft 312 Key projection 313 Through hole 32 Spiral fin (stirring conveyance blade)
321 Fin body 322 Connection cylinder 323 Exposure opening 324 Locking hole 33 Locking pin 40 Blowing mechanism 41 Fan device 42 Flat duct 421 Communication opening 43 Nozzle part 431 Nozzle body 432 Top plate 433 Nozzle hole 50 Drive mechanism 51 Driving force input part 511 Drive motor 511a Drive shaft 512 Drive gear 513 Input gear 52 Drive force output section 521 Output gear 522 Second idle gear 522a Second idle shaft 523 Second feeder gear 524 First idle gear 524a First idle shaft 525 First feeder gear P Paper P1 Paper bundle T Toner

Claims (4)

A predetermined housing;
A developing roller for supplying toner to the surface of a predetermined image carrier while rotating around the axis inside the housing;
An agitating and conveying member that is constructed to be rotatable about an axis between opposing wall surfaces in the casing, and that agitates the toner by rotating around the axis; and
The stirring and conveying member includes a metal shaft,
A stirring and conveying blade made of synthetic resin that rotates integrally with the shaft;
The stirring and conveying blade is provided with an exposure opening that exposes a part of the shaft into the housing.
The developing device, wherein the shaft end portion or a portion connected to the end portion is exposed to the outside from the housing.   The developing device according to claim 1, further comprising: a blowing mechanism for blowing an air flow to a portion of the stirring and conveying member exposed to the outside from the casing.   The developing device according to claim 1, wherein the portion connected to the end of the shaft is a driving force transmission gear.   The air blowing mechanism includes a fan device that takes in outside air, a duct that guides the outside air taken in by the fan device to the end portion side of the shaft, and a nozzle portion that is connected to a downstream end of the duct and blows outside air to the gear. The developing device according to claim 3, further comprising:

Images