JP2009139476A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device having a recovery conveyance path and a stir conveyance path which are located below a supply conveyance path, wherein the developing device is compact and prevents scattering of toner, which is caused by an increase in pressure in the developing device. <P>SOLUTION: A partition member separates: the supply conveyance path 2a along which developer is supplied to a developing sleeve 11; the recovery conveyance path 2b which is disposed below the supply conveyance path and recovers developer; the stir conveyance path which is disposed below the supply conveyance path, stirs and conveys developer supplied from the downstream area of the supply conveyance path and the downstream area of the recovery conveyance path, and transfers the developer to the upstream area of the supply conveyance path. A filter 5 for allowing the passage of air but not toner is disposed above the supply conveyance path. An opening 2f for supplying developer from the downstream area of the supply conveyance path to the stir conveyance path is disposed in a section extended upward from the lowest point of the supply conveyance path of the partition member 33 separating the supply conveyance path and the stir conveyance path. A ventilation opening 2g for ventilating the supply conveyance path and stir conveyance path is disposed further downstream than the opening 2f. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device used for a copying machine, a facsimile, a printer, and the like, and more particularly to a developing device using a two-component developer composed of toner and a magnetic carrier and an image forming apparatus using the same.

  Conventionally, as one of the developing devices, a supply conveyance path for supplying a developer to the developer carrying body while conveying the developer in the axial direction of the developer carrying body and a supply conveyance path for stirring the developer are: There is known an agitating / conveying path that conveys the developer in the reverse direction to circulate the developer. In such a developing device, when the developer on the developer carrying member that has passed through the development area is collected in the supply conveyance path, the developer in which the toner has been consumed in the development area and the developer in the supply conveyance path are mixed, The more developer that has passed through the development area, the more downstream the supply conveyance path. For this reason, there is a problem that the toner density of the developer supplied to the developer carrier decreases toward the downstream side of the supply conveyance path, and the image density differs between the upstream side and the downstream side in the conveyance direction.

  This problem can be solved by providing a recovery conveyance path that collects the developer separately from the supply conveyance path and the agitation conveyance path, as in the developing device described in Japanese Patent Application Laid-Open No. 2005-228867. In this developing device, a supply conveyance path for supplying the developer to the developer carrying member, a stirring conveyance path that is disposed below the supply conveyance path and conveys the developer in a direction opposite to the supply conveyance path, and a developer carrying member A recovery conveyance path that is disposed below and conveys the developer in the same direction as the supply conveyance path while collecting the developer from the developer carrying member is provided. The supply conveyance path, the recovery conveyance path, and the agitation conveyance path are each partitioned by a partition member, and the developer agitated in the supply conveyance path is supplied to the partition member with the supply conveyance path at the downstream end of the agitation conveyance path. A passing opening is provided. Also, the partition member for the agitating and conveying path at the downstream end of the supply conveying path is an opening for delivering the excess developer to the agitating and conveying path, and the partitioning member for the agitating and conveying path at the downstream end of the collecting and conveying path. Each has an opening for delivering the collected developer to the agitation transport path to circulate the developer. In this way, by separately performing the functions of supplying and collecting the developer to the developer carrying member, the toner concentration of the developer supplied to the developer carrying member becomes constant, and density unevenness is prevented. be able to.

  In general, in a developing apparatus, the ambient air is sucked into the apparatus due to the air flow generated by the rotation of the developer carrier, and the internal pressure in the apparatus rises, and the toner floating in the apparatus due to the pressure difference between the inside and outside of the apparatus. However, there is a problem in that the air scatters out of the device through a slight gap. Patent Document 2 describes a developing device provided with a filter that does not allow toner to pass therethrough and suppresses toner scattering from the developing device by suppressing an increase in internal pressure of the developing device. This is because the airflow in the developing device is discharged out of the device through the filter to suppress the increase in the internal pressure in the developing device, and the floating toner is carried on the airflow and collected by the filter, It suppresses toner scattering. In addition, the filter is installed on the upper side of the developing device to ensure sufficient ventilation and to prevent clogging of the filter, and the internal air pressure is increased by efficiently discharging the air flow in the developing device to the outside. It is suppressed.

JP 2001-290368 A JP-A-60-51861

  In the developing device in which the recovery conveyance path and the agitation conveyance path described above are provided below the supply conveyance path, the developer is recovered to the recovery conveyance path by the rotation of the developer carrier, and a peripheral airflow is generated in the recovery conveyance path. Take in and increase the internal pressure of the developing device. In order to prevent this increase in internal pressure, a filter is provided above the developing device, that is, above the supply conveyance path. Then, the airflow taken into the collection conveyance path is ventilated to the stirring conveyance path communicating with the collection conveyance path, and further to the upper supply conveyance path communicating with the agitation conveyance path, and the filter above the supply conveyance path I want to exhaust from. However, sufficient ventilation cannot be secured between the collection conveyance path and the filter, and toner scattering may occur without suppressing an increase in internal pressure in the collection conveyance path.

  In this developing apparatus, the collection conveyance path and the agitation conveyance path are communicated with each other through an opening provided on the side surface of the downstream portion of the collection conveyance path, but the developer is transferred at a lower portion of the opening where the developer exists. In the region where the bulk of the developer at the upper part of the opening is not reached, ventilation is performed. On the other hand, the stirring conveyance path and the upper supply conveyance path are communicated with each other by two openings provided on the upstream bottom surface and the downstream bottom surface of the supply conveyance path. Among these, the transfer of the developer from the downstream portion of the stirring conveyance path to the upper supply conveyance path causes the developer in the stirring conveyance path to overflow through the opening provided on the bottom surface on the upstream side of the supply conveyance path. As a result, the opening is likely to be blocked with the developer, and sufficient ventilation cannot be ensured. In addition, the developer is transferred from the upper supply conveyance path to the lower stirring conveyance path by dropping the developer through the opening provided on the bottom surface on the downstream side of the supply conveyance path. If the amount of the developer is large, the opening is closed with the developer and sufficient ventilation cannot be ensured. As described above, the opening where the lower agitation conveyance path and the upper supply conveyance path communicate with each other is likely to be clogged with the developer, and the upper supply conveyance path and the ventilation may not be ensured. If the upper supply conveyance path and sufficient ventilation cannot be ensured, the internal pressure remains elevated in the lower collection conveyance path and the stirring conveyance path.

  The supply conveyance path, the agitation conveyance path, and the opening that delivers the developer from the downstream portion of the supply conveyance path to the agitation conveyance path are extended to the downstream side in the axial direction, and the opening is not blocked by the developer and the agitation conveyance path and the agitation It is also conceivable to secure a region for venting the conveyance path. However, there is a demerit that the developing device becomes large.

  The present invention has been made in view of the above background, and the object of the present invention is to provide a recovery conveyance path for collecting and a stirring conveyance path for stirring below a supply conveyance path for supplying developer. It is an object of the present invention to provide a small developing device capable of preventing toner scattering due to an increase in internal pressure of the developing device and an image forming device using the developing device.

In order to achieve the above object, a first aspect of the present invention is to provide a developer carrying member that carries a developer composed of toner and a magnetic carrier and conveys the developer to a portion facing the latent image carrier by rotation, and the developer. A first developer conveying path having first developer agitating and conveying means for agitating and conveying the developer along the axial direction of the carrier and supplying the developer to the developer carrying body; and more than the first developer agitating and conveying means Second developer agitating and conveying means that is disposed below and collects the developer from the developer carrying body after passing through a portion facing the latent image carrier and conveys the developer in the same direction as the first developer agitating and conveying means. A second developer conveying path having a first developer agitating and conveying means disposed below the first developer agitating and conveying means without being supplied to the developer carrier by the first developer agitating and conveying means. A developer conveyed to a downstream portion in the conveyance direction of the path and the second developer agitating and conveying means. The developer is recovered from the developer carrying member and supplied to the downstream portion in the transport direction of the second developer transport path, and the developer is stirred and transported in the direction opposite to the first developer agitating and transporting means. A third developer conveying path having a third developer agitating and conveying means that is transferred downstream to the first developer agitating and conveying means, the first developer conveying path, and the second developer conveying path. And the third developer transport path is divided by a partition member,
A filter that allows air to pass without passing through the toner is provided above the first developer transport path, and a partition member that partitions the first developer transport path and the third developer transport path is the first developer. A first developer supply opening that extends upward from the lowest point of the transport path and supplies developer to the third developer transport path from a downstream portion in the transport direction of the first developer transport path. At a position above the lowest point of the first developer transport path of a partition member between the first developer transport path and the third developer transport path, and the first developer transport path and the third developer transport path. A ventilation opening for venting the developer conveyance path is located downstream of the first developer supply path in the conveyance direction of the first developer supply path and the first developer supply opening. It is characterized by being provided at a position above the uppermost part of the part.
According to a second aspect of the present invention, there is provided the developing device according to the first aspect, wherein the developer is transferred to the first developer agitating / conveying means downstream of the third developer agitating / conveying means in the developer conveying direction. 3. The developer carrier supplies toner to the latent image carrier through a third developer supply opening provided in a partition member with the first developer conveyance path downstream in the conveyance direction of the three developer conveyance path. It is characterized in that it is disposed within the development area width which is the width in the axial direction of the development area.
According to a third aspect of the present invention, there is provided the developing device according to the first or second aspect, wherein the first developer supply opening is disposed in the axial direction of the development region where the developer carrier supplies toner to the latent image carrier. It arrange | positions in the image development area width which is a width | variety.
According to a fourth aspect of the present invention, in the developing device according to any one of the first, second, and third aspects, the axial direction of the developing region where the developer carrying member supplies toner to the latent image carrying member through the ventilation opening. It is characterized in that it is disposed within the width of the development area which is the width of the above.
The invention of claim 5 comprises a latent image carrier, charging means for charging the latent image carrier, latent image forming means for forming an electrostatic latent image on the latent image carrier, An image forming apparatus having a developing unit for developing an electrostatic latent image into a toner image, wherein the developing unit of claim 1, 2, 3, or 4 is used as the developing unit. It is.

In the present invention, the bulk of the developer transported in the axial direction to the first developer supply opening in the first developer transport path reaches the height of the lowermost portion of the first developer supply opening. Spills down to the third developer transport path below through the first developer supply opening.
On the other hand, the developer that does not reach the lowest height of the first developer supply opening is supplied to the developer carrying member while being further conveyed to the downstream side. On the downstream side of the developer supply opening, the bulk of the developer gradually becomes lower than the lowest part of the first developer supply opening. Since the most downstream portion of the first developer conveyance path is a dead end, the bulk of the developer may increase at the most downstream portion. However, when the height reaches a certain level, development is performed against the first developer agitating and conveying means. The developer is pushed back to return to the first developer supply opening, and reaches the lowermost height of the first developer supply opening through the first developer supply opening. Spills into the agent transport path. Thus, the developer volume does not continue to increase on the downstream side of the first developer supply opening in the first developer transport path, and the gradient is in the vicinity of the lowermost portion of the first developer supply opening. It will be in an equilibrium state with By providing the ventilation opening at a position higher than the uppermost portion of the first developer supply opening, that is, at a position higher than this equilibrium state, the ventilation opening is blocked by the developer and the ventilation is not performed. There is little possibility of becoming sufficient, and sufficient ventilation can be secured in the third developer transport path and the first developer transport path.
In this manner, sufficient ventilation is ensured between the third developer conveyance path disposed below and the first developer conveyance path disposed above and provided with a filter through which air passes. Then, the air in the third developer transport path and the second developer transport path communicating with the third developer transport path is exhausted from the filter in the first developer transport path. Therefore, even if the internal pressure rises in the third developer transport path disposed below and the second developer transport path communicating with the third developer transport path, the upper first development provided with a filter that allows air to pass therethrough. The agent conveying path and sufficient ventilation can be ensured, and an increase in the internal pressure of the entire developing device can be suppressed.
Even if the first developer supply opening is provided at the lowest point of the first developer conveyance path, sufficient ventilation can be performed by the ventilation opening provided on the downstream side in the conveyance direction. However, in this case, most of the developer falls to the third developer transport path below at the first developer supply opening, and the developer carrier on the downstream side of the first developer supply opening. Insufficient developer supply is likely to occur. In order to avoid such problems and to provide the ventilation opening downstream of the first developer supply opening, it is necessary to extend the first developer conveyance path to the downstream side in the axial direction. The device becomes large.
In the present invention, the first developer supply opening is provided above the lowest point of the first developer conveyance path in the partition member between the first developer conveyance path and the third developer conveyance path, and the first development is further performed. By providing an opening for ventilation downstream of the opening for supplying the developer and above the uppermost portion of the opening for supplying the first developer, the developer is supplied also downstream of the opening for supplying the first developer. It is possible to provide a small-sized developing device that can suppress an increase in internal pressure without causing a shortage.

  As described above, according to the present invention, in a developing device including a collection conveyance path for collecting and a stirring conveyance path for stirring below a supply conveyance path for supplying developer, and an image forming apparatus using the same. There is an excellent effect that it is possible to provide a small apparatus capable of preventing toner scattering due to an increase in the internal pressure of the developing device.

  Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus will be described. FIG. 1 is a schematic configuration diagram of a main part of the image forming apparatus according to the present embodiment. In the image forming apparatus, a charging device 21, a developing device 1, an intermediate transfer device 23, a cleaning device 28, and the like are disposed around a photosensitive drum 100 that is a latent image carrier. An exposure device 22 is provided below these. Further, a secondary transfer device 25 and a fixing device 27 are provided on the side of the intermediate transfer device 23.

  The photosensitive drum 100 is uniformly charged by the charging device 21 while rotating counterclockwise in the figure, and an information signal is exposed by a light emitting element such as a laser from the exposure device 22 to form an electrostatic latent image. The The electrostatic latent image on the photosensitive drum 100 is converted into a toner image by the developing device 1, and the formed toner image is transferred onto the intermediate transfer belt 24 by the intermediate transfer device 23. A toner image by another developing device (not shown) can be transferred onto the intermediate transfer belt 24, and a color image in which different color toners are superimposed can be created. The toner image on the intermediate transfer belt 24 is transferred onto the transfer paper 26 by the secondary transfer device 25 and further fixed by the fixing device 27 to obtain a permanent image. The transfer residual toner on the photosensitive drum 100 is removed by the cleaning device 28, and the photosensitive drum 100 is used for the next image formation.

  FIG. 2 is a cross-sectional view illustrating a schematic configuration of the developing device. The developing device 1 includes a developing container 2 containing a two-component developer, and a developing sleeve 11 serving as a developer carrying member is formed with a predetermined distance from the photosensitive drum 100 at an opening of the developing container 2 facing the photosensitive drum 100. It is installed so as to be freely rotatable with an interval of. The developing sleeve 11 is made of a non-magnetic cylindrical material, and rotates in the direction in which the facing portion moves in the same direction with respect to the photosensitive drum 100 rotating in the direction of the arrow. Inside the developing sleeve 11, a magnet roller as a magnetic field generating means is arranged so as not to rotate with respect to the rotation of the developing sleeve 11. The magnet roller has five magnetic poles N1, S1, N2, N3, and S2. A magnetic member regulating blade 30 is attached to the portion of the developing container 2 above the developing sleeve 11, and the regulating blade 30 is directed toward the vicinity of the magnetic pole S <b> 2 that is substantially positioned at the uppermost point in the vertical direction of the magnet roller. And arranged in non-contact.

  In the developing container 2, a supply screw 4 serving as a first developer stirring and conveying unit, a recovery screw 6 serving as a second developer stirring and conveying unit, and a stirring screw 7 serving as a third developer stirring and conveying unit are accommodated. There are provided three developer transport paths: a path 2a, a recovery transport path 2b, and a stirring transport path 2c. The supply conveyance path 2a and the agitation conveyance path 2c are arranged obliquely in the vertical direction. Further, the collection conveyance path 2b is disposed on the downstream side of the developing region of the developing sleeve 11 and on a side substantially horizontal to the stirring conveyance path 2c.

  The two-component developer accommodated in the developing container 2 is circulated and conveyed through the supply conveyance path 2a, the collection conveyance path 2b, and the agitation conveyance path 2c by stirring and conveyance of the supply screw 4, the recovery screw 7 and the stirring screw 6. The toner is supplied to the developing sleeve 11 from the supply conveyance path 2a. The developer supplied to the developing sleeve 11 is pumped onto the developing sleeve 11 by the magnetic pole N2 of the magnet roller. As the developing sleeve 11 rotates, the developing sleeve 11 is conveyed from the magnetic pole S2 to the magnetic pole N1 and from the magnetic pole N1 to the magnetic pole S1, and reaches the developing area where the developing sleeve 11 and the photosensitive drum 100 face each other. During the conveyance, the developer is magnetically regulated by the regulating blade 30 in cooperation with the magnetic pole S2, and a thin layer of developer is formed on the developing sleeve 11. The magnetic pole S1 of the magnet roller located in the developing area in the developing sleeve 11 is a developing main pole, and the developer conveyed to the developing area rises by the magnetic pole S1 and comes into contact with the surface of the photosensitive drum 100, and is exposed to light. The electrostatic latent image formed on the surface of the drum 100 is developed. The developer that has developed the latent image passes through the developing region as the developing sleeve 11 rotates, returns to the developing container 2 through the transport pole N3, and is separated from the developing sleeve 11 by the repulsive magnetic field of the magnetic poles N2 and N3. It is collected in the collection conveyance path 2b by the collection screw 6.

  The supply conveyance path 2 a and the collection conveyance path 2 b obliquely below are partitioned by a first partition member 31.

  The collection conveyance path 2b and the agitating conveyance path 2c arranged on the side are partitioned by the second partition member 32, but the collected developer is located downstream in the conveyance direction by the collection screw 6 of the collection conveyance path 2b. Is provided with a developer supply opening for supplying the toner to the agitating and conveying path 2c. FIG. 3 is a cross-sectional view of the collection conveyance path 2b and the agitation conveyance path 2c at the downstream portion in the conveyance direction by the collection screw 6, and an opening 2d that connects the collection conveyance path 2b and the agitation conveyance path 2c is provided. .

  Further, the supply conveyance path 2a and the stirring conveyance path 2c arranged obliquely below are partitioned by the third partition member 33, but in the upstream and downstream portions in the conveyance direction by the supply screw 4 of the supply conveyance path 2a. A developer supply opening for supplying the developer is provided. FIG. 4 is a cross-sectional view of the developing device 1 at the upstream portion in the conveyance direction by the supply screw 7, and the third partition member 33 is provided with an opening 2 e that communicates the agitation conveyance path 2 c and the supply conveyance path 2 a. FIG. 5 is a cross-sectional view of the developing device 1 at the downstream portion in the conveyance direction by the supply screw 7. The third partition member 33 is provided with an opening 2 f that communicates the agitation conveyance path 2 c and the supply conveyance path 2 a. Yes.

Next, the circulation of the developer in the three developer conveyance paths will be described.
FIG. 6 is a schematic diagram of the developer flow in the developing device 1. Each arrow in FIG. 6 indicates the moving direction of the developer. In the supply conveyance path 2 a that receives the developer supplied from the agitation conveyance path 2 c, the developer is conveyed downstream in the conveyance direction of the supply screw 4 while supplying the developer to the developing sleeve 11. The surplus developer conveyed to the downstream side in the conveyance direction of the supply conveyance path 2 a without being supplied to the developing sleeve 11 is from an opening 2 f as a first developer supply opening provided in the third partition member 33. It is supplied to the agitation transport path 2c.
Further, the recovered developer that is recovered from the developing sleeve 11 to the recovery transport path 2b by the recovery screw 6 and transported to the downstream portion in the transport direction in the same direction as the developer in the supply transport path 2a is provided in the second partition member 32. The developer is supplied to the stirring and conveying path 2c from the opening 2d as the second developer supply opening.
In the agitating and conveying path 2c, the surplus developer and the recovered developer supplied by the agitating screw 7 are agitated and conveyed in the opposite direction to the developer in the collecting and conveying path 2b and the supplying and conveying path 2a. The developer conveyed downstream in the conveyance direction of the agitation conveyance path 2 c is upstream in the conveyance direction of the supply conveyance path 2 a from the opening 2 e serving as the third developer supply opening provided in the third partition member 33. Supplied to the department.

  A toner concentration sensor (not shown) is provided below the agitation transport path 2c, and a toner supply control device (not shown) is operated by the sensor output to supply toner from a toner container (not shown). . In the agitating and conveying path 2c, the toner replenished from the toner replenishing port 3 as necessary is conveyed by the agitating screw 7 to the downstream side in the conveying direction while being agitated with the collected developer and the surplus developer. When replenishing toner, replenishing upstream of the agitation screw 7 can increase the agitation time from replenishment to development.

  As described above, the developing device 1 includes the supply conveyance path 2a and the collection conveyance path 2b, and the developer is supplied and collected in different developer conveyance paths, so that the developed developer is mixed into the supply conveyance path 2a. There is nothing to do. Therefore, it is possible to prevent the toner concentration of the developer supplied to the developing sleeve 11 from decreasing toward the downstream side of the supply conveyance path 2a in the conveyance direction. Further, since the recovery conveyance path 2b and the agitation conveyance path 2c are provided and the developer is collected and stirred in different developer conveyance paths, the developed developer does not fall during the agitation. Therefore, since the sufficiently agitated developer is supplied to the supply conveyance path 2a, it is possible to prevent the developer supplied to the supply conveyance path 2a from being insufficiently agitated. In this way, the toner density of the developer in the supply conveyance path 2a can be prevented from decreasing, and the developer in the supply conveyance path 2a can be prevented from being insufficiently stirred, so the image density during development can be reduced. Can be constant.

  Further, in the upstream portion in the conveyance direction of the supply conveyance path 2a shown in FIG. 4, the developer is supplied from the stirring conveyance path 2c disposed obliquely downward to the upper supply conveyance path 2a. In the delivery of the developer, the developer is pushed up by the rotation of the stirring screw 7 so that the developer is raised and overflows from the opening 2e to supply the developer to the supply conveyance path 2a. Such movement of the developer gives stress to the developer and contributes to a decrease in the life of the developer. In the developing device 1, the supply conveyance path 2a is disposed so as to be obliquely above the agitation conveyance path 2c, so that the supply conveyance path 2a is provided vertically above the agitation conveyance path 2c, and the developer is lifted, It is possible to reduce the developer stress in the upward movement of the developer.

Next, features of the present invention will be described.
In the downstream portion in the conveyance direction by the supply screw 7 shown in FIG. 5, the supply conveyance path 2a and the agitation conveyance are performed in order to supply the developer from the supply conveyance path 2a disposed above to the agitation conveyance path 2c disposed obliquely below. An opening 2f that communicates with the path 2c is provided. Here, the third partition member 33 that partitions the stirring conveyance path 2c and the supply conveyance path 2a extends upward from the lowest point of the supply conveyance path 2a, and the opening 2f is located above the lowest point. Is provided. FIG. 7 is a cross-sectional view of the developing device 1 at the most downstream portion in the conveyance direction by the supply screw 7. As shown in FIG. 7, an opening 2 g that communicates the stirring and conveying path 2 c and the supply and conveying path 2 a with the third partition member 33 is provided downstream of the opening 2 f in the conveying direction by the supply screw 7. Yes. The opening 2g is provided above the top of the opening 2f.

  FIG. 8 is an explanatory diagram showing changes in the opening provided in the supply conveyance path 2a and the bulk of the developer. In the supply conveyance path 2a having the openings 2f and 2g, the bulk of the developer conveyed in the axial direction through the supply conveyance path 2a to the opening 2f by the supply screw 7 reaches the lowest height of the opening 2f. Things fall down to the lower agitating and conveying path 2c through the opening 2f. On the other hand, the developer that does not reach the lowermost height of the opening 2 f is supplied to the developing sleeve 11 while being conveyed further downstream by the supply screw 7. Therefore, on the downstream side of the opening 2f in the supply conveyance path 2a, the volume of the developer gradually becomes lower than the lowest part of the opening 2f. Since the most downstream portion of the supply conveyance path 2a is a dead end, the bulk of the developer may increase in the most downstream portion. However, when the height reaches a certain level, the developer is pushed back against the supply screw 7 and opened. What returns to the portion 2f and reaches the lowest height of the opening 2f spills down to the lower stirring and conveying path 2c through the opening 2f. Thus, on the downstream side of the opening 2f of the supply conveyance path 2a, the bulk of the developer does not continue to increase, and an equilibrium state with a gradient near the bottom of the opening 2f is obtained. By providing the opening 2g at a position higher than the uppermost part of the opening 2f, that is, a position higher than this equilibrium state, there is little possibility that the opening 2f is blocked by the developer and the ventilation becomes insufficient. Sufficient ventilation can be ensured by the stirring conveyance path 2c and the supply conveyance path 2a. That is, the opening 2g does not function as a developer supply opening between the supply conveyance path 2 and the agitation conveyance path 2c, and ensures sufficient ventilation between the supply conveyance path 2 and the agitation conveyance path 2c. It fulfills the function as an opening for ventilation. By providing such an opening 2g for ventilation, a filter that allows air to pass therethrough is provided even if the internal pressure rises in the agitation conveyance path 2c disposed below and the recovery conveyance path 2b communicating with the agitation conveyance path 2c. Further, it is possible to ensure sufficient ventilation with the upper supply conveyance path 2a, and it is possible to suppress an increase in internal pressure of the entire developing device 1.

  Even if the developer supply opening on the downstream side of the supply conveyance path 2a is provided at the lowest point of the supply conveyance path 2a, the ventilation opening provided on the downstream side in the conveyance direction can provide sufficient ventilation. . However, in this case, most of the developer falls to the lower agitating / conveying path 2c at the developer supply opening, and there is insufficient developer supply to the developing sleeve 11 on the downstream side of the developer supply opening. Likely to happen. In order to avoid such problems and to provide the ventilation opening downstream of the image agent supply opening, it is necessary to extend the supply conveyance path 2a to the downstream side in the axial direction, which increases the size of the developing device. End up.

  In the developing device 1 of the present embodiment, the openings 2f and 2g are provided in a portion extending upward from the lowest point of the supply conveyance path 2a by the third partition member 33 of the supply conveyance path 2a and the agitation conveyance path 2c. As a result, it is possible to provide a small-sized developing device that can suppress an increase in internal pressure without fear of insufficient supply of the developer even on the downstream side of the opening 2f.

  Further, in the developing device 1, an opening 2e that supplies the developer to the supply conveyance path 2c in the downstream portion of the stirring conveyance path 2c, and the width in the axial direction of the development area in which the developing sleeve 11 supplies toner to the photosensitive drum 100 are provided. It is arranged within the development area width. As a result, the supply conveyance path 2a and the agitation conveyance path 2c are shorter than those in which the opening 2e is provided outside the development region width. Therefore, the space occupied by the supply conveyance path 2a and the stirring conveyance path 2c can be reduced, and the apparatus can be downsized.

  In addition, an opening 2f for supplying the developer to the stirring and conveying path 2c is disposed within the developing region width at a downstream portion of the supply and conveying path 2a. Thereby, the supply conveyance path 2a and the agitation conveyance path 2c are shorter than those in which the opening 2f is provided outside the development region width. Therefore, the space occupied by the supply conveyance path 2a and the stirring conveyance path 2c can be reduced, and the apparatus can be downsized.

  In addition, an opening 2g that ventilates with the agitation conveyance path 2c at the most downstream portion of the supply conveyance path 2a is disposed within the width of the development area. Thereby, the supply conveyance path 2a and the agitation conveyance path 2c are shorter than those in which the opening 2g is provided outside the width of the development region. Therefore, the space occupied by the supply conveyance path 2a and the stirring conveyance path 2c can be reduced, and the apparatus can be downsized.

  In the developing device 1 of the present embodiment, the supply conveyance path 2a and the agitation conveyance path 2c are arranged obliquely in the vertical direction, and the collection conveyance path 2b and the agitation conveyance path 2c are arranged substantially horizontally. The present invention is not limited to this as long as the conveyance path 2b and the stirring conveyance path 2c are arranged below the supply conveyance path 2a. For example, the present invention can also be applied to the developing device of Patent Document 1 in which the agitation conveyance path 2c is disposed directly below the supply conveyance path 2a. Also in this case, in the conventional developer supply opening, the opening is blocked with the developer, and sufficient ventilation cannot be ensured between the supply conveyance path and the agitation conveyance path arranged above and below. By arranging the opening 2f as the developer supply opening and the opening 2g as the ventilation opening as described above in the downstream of the supply conveyance path 2a arranged above, the air passes. It is possible to ensure sufficient ventilation with the upper supply conveyance path 2a provided with the filter to suppress the increase in the internal pressure of the entire developing device.

As described above, the developing device 1 of the present embodiment has the first supply screw 4 as the first developer agitating / conveying means that agitates and conveys the developer composed of the toner and the magnetic carrier in the axial direction and supplies the developer to the developing sleeve 11. The developer is collected from the developing sleeve 11 after passing through the facing portion between the supply conveyance path 2a as the developer conveyance path and the photosensitive drum 100 as the latent image carrier disposed below the supply screw 4 and supplied. A recovery conveyance path 2b as a second developer conveyance path having a collection screw 6 as a second developer agitating and conveyance means that conveys in the same direction as the screw 4 and a supply screw 4 are arranged below the supply screw 4. The developer that has not been supplied to the developing sleeve 11 and has been transported to the downstream portion of the supply transport path 2a, and is recovered from the developing sleeve 11 by the recovery screw 6 and recovered and transported. As a third developer agitating and conveying means that receives the developer conveyed to the downstream portion in the conveying direction of 2b, agitates and conveys the developer in the direction opposite to the supply screw 4 and delivers it to the supply screw 4 on the downstream side And a stirring / conveying path 2c as a third developer conveying path having the agitating screw 7. The supply conveyance path 2a, the collection conveyance path 2b, and the agitation conveyance path 2c are partitioned by a first partition member 31, a second partition member 32, and a third partition member 33, respectively. In the developing device 1, a filter that allows air to pass therethrough is provided above the supply conveyance path 2a. Moreover, the 3rd partition member 33 which partitions off the supply conveyance path 2a and the stirring conveyance path 2c is extended upwards from the supply conveyance path 2a lowest point. As a first developer supply opening for supplying the developer from the downstream side in the conveyance direction of the supply conveyance path 2a to the agitation conveyance path 2c, an opening is provided above the lowest point of the supply conveyance path 2a of the third partition member 33. 2f is provided. Furthermore, as a ventilation opening for ventilating the supply conveyance path 2a and the agitation conveyance path 2c, a third downstream of the opening 2f in the conveyance direction of the supply screw 4 and above the uppermost part of the opening 2f. An opening 2 g is provided in the partition member 33. Thereby, sufficient ventilation is ensured by the opening part 2g between the stirring conveyance path 2c and the supply conveyance path 2a provided with the filter. And the internal pressure rise of the stirring conveyance path 2c and the collection conveyance path 2b can be suppressed by exhausting the air in the collection conveyance path 2b communicating with the stirring conveyance path 2c from the filter via the supply conveyance path 2a.
Further, an opening 2e that supplies the developer to the supply conveyance path 2c in the downstream portion of the agitation conveyance path 2c, and a development area width that is the width in the axial direction of the development area where the developing sleeve 11 supplies toner to the photosensitive drum 100. Place in. As a result, the supply conveyance path 2a and the agitation conveyance path 2c are shortened as compared with the case where the opening 2e is provided outside the width of the development area, and the apparatus can be downsized.
In addition, an opening 2f for supplying the developer to the stirring and conveying path 2c is disposed within the developing region width at a downstream portion of the supply and conveying path 2a. As a result, the supply conveyance path 2a and the agitation conveyance path 2c are shortened compared to those in which the opening 2f is provided outside the width of the development region, and the apparatus can be downsized.
In addition, an opening 2g that ventilates with the agitation conveyance path 2c at the most downstream portion of the supply conveyance path 2a is disposed within the width of the development area. As a result, the supply conveyance path 2a and the agitation conveyance path 2c are shortened compared with the case where the opening 2g is provided outside the width of the development area, and the apparatus can be downsized.

1 is a schematic configuration diagram of a main part of an image forming apparatus according to an embodiment. Sectional drawing which shows schematic structure of a developing device. Sectional drawing of the collection conveyance path and the stirring conveyance path in the conveyance direction downstream part of a collection conveyance path. Sectional drawing in the conveyance direction upstream part of the supply conveyance path of a developing device. Sectional drawing in the conveyance direction downstream part of the supply conveyance path of a developing device. FIG. 6 is a schematic diagram of a developer flow in the developing device. Sectional drawing in the conveyance direction most downstream part of the supply conveyance path of a developing device. Explanatory drawing which shows the change of the opening part provided in the supply conveyance path, and the volume of a developing agent.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developer 2 Developer container 2a Supply conveyance path (1st developer conveyance path)
2b Collection transport path (second developer transport path)
2c Agitation conveyance path (third developer conveyance path)
2d opening (second developer supply opening)
2e Opening (third developer supply opening)
2f opening (first developer supply opening)
2g opening (ventilation opening)
3 Toner replenishment port 4 Supply screw (first developer stirring and conveying means)
5 Filter 6 Recovery screw (second developer stirring and conveying means)
7 Stirring screw (third developer stirring and conveying means)
DESCRIPTION OF SYMBOLS 10 Developer 11 Developing sleeve 21 Charging device 22 Exposure device 23 Intermediate transfer device 24 Intermediate transfer belt 25 Secondary transfer device 26 Transfer paper 27 Fixing device 28 Cleaning device 30 Regulator blade
31 1st partition member 32 2nd partition member 33 3rd partition member 100 Photosensitive drum

Claims (5)

A developer carrier that carries a developer composed of toner and a magnetic carrier and conveys the developer to a portion facing the latent image carrier by rotation;
A first developer conveying path having first developer agitating and conveying means for agitating and conveying the developer along the axial direction of the developer carrying member and supplying the developer to the developer carrying member;
The developer is disposed below the first developer agitating / conveying means, and the developer is recovered from the developer carrying body after passing through the portion facing the latent image carrier, and is in the same direction as the first developer agitating / conveying means. A second developer conveying path having a second developer stirring and conveying means for conveying
The first developer agitating / conveying means is disposed below the first developer agitating / conveying means, and is not supplied to the developer carrier by the first developer agitating / conveying means, but is conveyed to the downstream portion in the conveying direction of the first developer conveying path. The first developer is supplied with the developer and the developer collected from the developer carrier by the second developer agitating and conveying means and conveyed to the downstream portion in the conveying direction of the second developer conveying path. A third developer conveying path having third developer agitating and conveying means that agitates and conveys the developer in the opposite direction to the agitating and conveying means and delivers the developer to the first developer agitating and conveying means on the downstream side;
In the developing device in which the first developer transport path, the second developer transport path, and the third developer transport path are partitioned by a partition member,
A filter that allows air to pass through without passing toner is provided above the first developer transport path,
The partition member that partitions the first developer transport path and the third developer transport path extends upward from the lowest point of the first developer transport path,
A first developer supply opening for supplying developer to the third developer transport path from a downstream portion in the transport direction of the first developer transport path is formed between the first developer transport path and the third development. Provided at a position above the lowest point of the first developer transport path of the partition member with the developer transport path,
A ventilation opening for ventilating the first developer conveyance path and the third developer conveyance path is disposed downstream of the first developer conveyance path in the conveyance direction with respect to the first developer supply opening. And a developing device provided at a position above the uppermost portion of the first developer supply opening.   2. The developing device according to claim 1, wherein transport of the third developer transport path is performed in order to deliver the developer to the first developer stir transport unit downstream of the third developer stir transport unit in the developer transport direction. A third developer supply opening provided in a partition member between the first developer transport path and a downstream portion in the direction of the direction of the axial direction of the developing region in which the developer carrier supplies toner to the latent image carrier. A developing device, wherein the developing device is disposed within a width of a developing area which is a width.   3. The developing device according to claim 1, wherein the first developer supply opening is within a development region width that is a width in the axial direction of a development region where the developer carrier supplies toner to the latent image carrier. A developing device characterized by being arranged in   4. The developing area width according to claim 1, wherein the developing opening is a width in the axial direction of a developing area where the developer carrying member supplies toner to the latent image carrying body through the ventilation opening. A developing device arranged inside. A latent image carrier, a charging means for charging the latent image carrier, a latent image forming means for forming an electrostatic latent image on the latent image carrier, and developing the electrostatic latent image. And an image forming apparatus having a developing unit for forming a toner image.
An image forming apparatus using the developing device of claim 1, 2, 3, or 4 as the developing means.

Images