JP2007102065A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus wherein the inner pressure rise of a developing vessel which causes toner scattering can be stably suppressed for a long period of time without considerable increase in installation space or cost by a simple configuration effectively utilizing other equipment as far as possible. <P>SOLUTION: In a developing device (14) using a developer (G) containing toner and carrier, an exhaust port (61) through which excessive air (E) accompanying the inner pressure rise of a developing vessel (40) is exhausted is provided in a state of sharing at least a part of a leak port (51) through which a part of the developer (G) is leaked from the developing vessel. An exhaust path (62) for exhausting the air (E) exhausted from the exhaust port (61) shares at least a partial section of a conveyance pipe (53) for a leaked developer (G') leaked out from the leak port (51). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, or a multi-function machine having a developing device that uses a dry developer, and in particular, due to an increase in internal pressure of a developing container that stores the developer of the developing device. The present invention relates to an improvement of an image forming apparatus in which measures for preventing problems that occur are applied.

  In an image forming apparatus such as a printer to which an electrophotographic system or an electrostatic recording system is applied, an electrostatic latent image formed on an image carrier such as a photoconductor is developed with a dry developer supplied from a developing device, and a toner image is developed. After the toner image is formed, the toner image is transferred to a recording medium such as recording paper directly or via an intermediate transfer member, and further fixed to form an image made of toner. When a (two-component) developer containing toner and carrier is used as the developer, the development is performed with toner, without needing to be described in detail.

  By the way, in such an image forming apparatus, the internal pressure of the developing container that stores the developer of the developing apparatus is in an internal state with a high degree of sealing by attaching the sealing material of the container, or the image is carried by the developer. Increased due to factors such as the generation of an air flow accompanying the rotation of the developing roll transported to the developing area facing the carrier, which causes the developer (toner in the case of a two-component developer) to carry an image. In some cases, a problem such as scattering in the developing area between the body and floating in the image forming apparatus may occur.

  On the other hand, conventionally, a developing device and an image forming apparatus have been proposed in which measures capable of eliminating such problems are provided.

  For example, a vent hole is provided in the peripheral wall portion of the developing tank in which the developing roll is arranged in the casing of the developing device, and a filter that closes the vent hole is provided, or a receiving tray is provided below the filter and unitized with the filter. There is a developing device that is detachably attached to the developing tank (Patent Document 1).

  According to this developing device, the internal pressure air generated in the closed space in the casing can escape from the casing to the outside of the casing to suppress the increase in internal pressure, and the toner and the like contained in the air can be removed by the filter. Further, since the unitized tray and filter can be taken out and cleaned, the maintenance can be simplified.

  In addition, in an image forming apparatus using a developing device that can store a part of the developer in a waste developer container by means of automatic two-component developer replacement, an opening for releasing pressure in the developing container of the developing device is provided. An exhaust duct for discharging the air in the developing device to the outside of the image forming apparatus through the opening, and allowing the exhaust duct to pass through the waste developer container, and the waste developer container. There is an image forming apparatus provided with a toner filter (Patent Document 2).

  According to this image forming apparatus, the internal pressure in the developing container is not easily increased by the exhaust duct and toner scattering can be reduced, and the waste developer container is disposed by passing the waste duct to the waste developer container and installing the toner filter. The toner filter can be replaced at a time when the toner is replaced or collected, so that the maintenance is facilitated and the maintenance of the developing device itself becomes unnecessary. Further, since the toner captured by the toner filter can be collected in the waste developer container, the filter replacement timing can be extended.

JP 61-140968 A JP 2003-15420 A

  However, the developing devices and image forming apparatuses proposed above have the following problems.

  That is, in the developing device proposed in Patent Document 1, it is necessary to detachably install a unit composed of a filter and a tray in the developing container of the developing device, which is disadvantageous in reducing the size of the developing device. In addition, since the ventilation hole and the filter are provided in the upper part of the developing tank of the developing container, the positional relationship is close to the part where the toner cloud where the toner floats around the developing roll rotating in the developing tank is generated. In particular, a relatively large amount of toner is captured by the filter, so that the life of the filter is shortened, and maintenance work must be frequently performed to maintain the filter performance.

  In the image forming apparatus proposed in Patent Document 2, it is necessary to separately install a dedicated exhaust duct in a state in which the exhaust duct is routed in the apparatus, and thus there are problems associated with reducing the size and cost of the image forming apparatus. . Also, if the exhaust duct is separated from the air flow at the horizontal part or the upward inclined part leading to the waste developer container, it will accumulate in the duct as there is no means to convey the toner, The inside of the duct is easily clogged.

  The present invention has been made in view of the above-described problems. The increase in the internal pressure of the developing container, which causes toner scattering, can be increased as much as possible without causing a significant increase in installation space and cost. It is an object of the present invention to provide an image forming apparatus that can be stably suppressed over a long period of time with a simple configuration that effectively uses equipment.

  The image forming apparatus of the present invention conveys a developer container in which a developer containing toner and a carrier is accommodated, a developer container in which a developing opening is formed, and the developer accommodated in the developer container container while stirring the developer. An agitating / conveying member, a developer carrying member that is provided in the developing opening of the developing container and rotates so as to carry the developer agitated by the agitating / conveying member and convey the developer to the developing region, and the agitating / conveying member A developing device having a leak outlet for leaking a part of the developer provided in the housing portion of the developer container around the member, and a recovery for collecting the leaked developer leaked from the leak port of the developer device An image forming apparatus comprising a container and a transport pipe for connecting the recovery container and the leak outlet and transporting the leaked developer to the recovery container, and is generated as the internal pressure of the developer container increases. Exhaust excess air A discharge port is provided in a state in which at least a part of the leakage port is shared, and an exhaust path for exhausting air discharged from the discharge port is shared by at least a part of the transport pipe. To do.

  Here, there are generally a plurality of the developing devices, but one developing device may be used. When there are a plurality of developing devices, from the viewpoint of space saving, etc., the number of the collecting containers is one, and the conveying pipes are connected so as to be aggregated from the developing devices to finally become one conveying pipe. It is good to comprise so that the part used as the one conveyance pipe may be connected to the said one collection container.

  If the outlet has an opening having a sufficient opening area for discharging excess air generated by an increase in internal pressure, the outlet can be used as an outlet as it is. However, since the opening area of the leakage outlet is usually narrow, the discharge opening in this case is expanded by extending the opening area of the leakage opening in a direction (such as upward) that does not impair the developer leakage function. It is preferable to form so as to ensure a sufficient opening area for exhausting fresh air.

  The exhaust path needs to have a space (gap space) that allows at least a portion that shares the leaked developer conveyance pipe to move when excess air discharged from the discharge port flows. Further, this exhaust path may be configured to share the entire section from the transport pipe to the collection container. Furthermore, the final exhaust destination of the air exhausted to the exhaust path becomes an exhaust port provided in a collection container connected to the middle part of the transport pipe shared as the exhaust path or its terminal part as described later.

  In the image forming apparatus, a ventilation space that connects the developer carrier and the discharge port may be formed on the upper inner surface side of the developing container in the developing device. In particular, if there is a part that obstructs the flow of air flow between the developer carrying member and the discharge port in the developing container, for example, if there is a partition plate of the housing part, the obstacle part (the upper end part of the partition plate) is removed from the developing container. It also includes an improvement to a state where a space is formed between the upper inner wall surface and a space in which air flows favorably toward the discharge port.

  When configured in this manner, the air generated as the internal pressure rises in the developing container can be smoothly and efficiently flowed to the discharge port to be discharged, which is effective in suppressing the increase in internal pressure.

  In each of the developing devices, an exhaust port may be provided in the collection container, and a dust removal filter may be attached to the exhaust port. In this case, all the sections of the leakage developer conveying path are shared as a ventilation path except that another exhaust pipe described later is provided.

  In such a configuration, since the recovery container is usually of a cross-sectional (volume) shape larger than the cross-sectional area of the transport pipe or the developing container of the developing device, an exhaust port is connected to the recovery container. An exhaust port having a larger opening area than the cross section of the developer container and the cross section of the developing container can be provided. As a result, a filter having a large area can be used correspondingly, thereby extending the life of the filter. be able to. In this case, since the air discharged from the discharge port moves through a long section in which the air reaches the collection container through the entire section of the exhaust pipe shared as a ventilation path, the toner contained in the air in the section This also increases the rate at which the toner is separated from the air and falls into the exhaust pipe, thereby reducing the amount of toner contained in the air when passing through the filter at the exhaust port of the recovery container. The lifetime of the filter can be extended.

  Further, in each of the developing devices, an exhaust port is provided in a part of a transport pipe shared as the exhaust path or an exhaust unit installed by connecting to the transport pipe, and a dust removing filter is attached to the exhaust port. Good. The exhaust unit has a space for introducing air that is discharged from the discharge port and flows through a conveyance pipe shared as an exhaust path, and an exhaust port is provided in a portion forming the space, or in the space This is a dedicated container in which a dust removal filter can be installed or an exhaust port can be provided and a dust removal filter can be installed in the exhaust port.

  When configured in this way, the position of the exhaust port can be selected as an arbitrary position of the transport pipe that is shared as the exhaust path, and the distance (path length) between the exhaust port and the exhaust port can be freely selected. Thus, for example, the distance can be shortened, and in this case, the excess air discharged from the discharge port can be flowed well toward the exhaust port located near the discharge port with little pressure loss. Can be exhausted. Further, when an exhaust port is provided in the exhaust unit, an exhaust port having an opening area wider than the cross section of the transport pipe can be provided in the exhaust unit, and accordingly, a filter having a large area is used. Therefore, the life of the filter can be extended.

  In each of the image forming apparatuses, a rotation conveyance member having a helical conveyance blade for conveying the leaked developer may be installed in a part of a conveyance pipe shared as the exhaust path.

  In such a configuration, since the air flowing through the transport pipe hits the transport blades of the rotary transport member and receives resistance, the toner contained in the air is separated from the air flow and enters the transport pipe. Fall. As a result, the amount of toner in the airflow that reaches the filter disposed on the downstream side of the rotary conveying member is reduced, so that the life of the filter can be extended. Incidentally, the toner that has been separated and dropped into the transport tube at this time is transported toward the collection container by a rotating transport member (transport blade) installed in the transport tube.

  Further, in each of the image forming apparatuses, a part of the exhaust path may be configured by a vent pipe different from the transport pipe. As such a vent pipe different from the transport pipe, for example, a type provided corresponding to a section in which the function as an exhaust path is impaired by being filled with toner, such as a specific section of the transport pipe described later, There is a bypass type that is short-circuited from the middle of the transfer pipe to the collection container.

  When configured in this way, excess air discharged from the discharge port can be smoothly flowed through the dedicated ventilation pipe regardless of the degree of air permeability of the transport pipe, or in the case of a bypass-type ventilation path Can efficiently flow from the outlet to the collection container. As a result, a good exhaust function of excess air (exhaust air) can be ensured, so that an increase in the internal pressure of the developing container can be satisfactorily suppressed.

  In addition, a vent pipe as an exhaust path different from the transport pipe may be provided in a region corresponding to an upward inclined section in which the leaked developer is transported obliquely upward.

  When configured in this way, the upward inclined section of the transport pipe is easily filled with toner accumulation and is difficult to function as an exhaust path. By providing a dedicated ventilation pipe corresponding to such an inclined section, Since it is possible to ensure a good exhaust function of the exhaust air in the corresponding section, it is possible to satisfactorily suppress an increase in the internal pressure of the developing container.

  According to the image forming apparatus of the present invention, the air generated as the internal pressure rises during the developing operation of the developing container in the developing device is discharged from the discharge port shared with a part of the leakage port of the developing device. The air is exhausted through a partial section of a transport pipe for transporting the developer.

  As described above, in the image forming apparatus, in particular, the developer container is formed so as to share a part of the air discharge port generated due to the increase of the internal pressure and the developer leakage port, and the discharged air vent is leaked. Since a part of the transport pipe that is connected between the outlet and the recovery container and transports the leaked developer is shared, the component for exhausting the air when the internal pressure rises is installed in other equipment (development). The rate at which new components are used by effectively utilizing the agent leakage recovery mechanism), which can cause toner scattering without significantly increasing installation space and costs. An increase in the internal pressure of the developing container can be suppressed with a simple configuration. As a result, it is possible to prevent the occurrence of toner scattering due to the increase in internal pressure.

  Further, since the toner contained in the discharged air can be removed not in the developing device but in other parts, a larger one than the filter provided in the developing device is used. When configured in this manner, the filter life can be extended, and as a result, the phenomenon of the internal pressure increase of the developing container can be stably suppressed over a long period of time. In addition, since it is not necessary to secure a space for installing a duct or a filter in the developing device, it is possible to prevent the developing device from becoming large.

[Embodiment 1]
FIG. 1 shows a main part of a full-color printer according to Embodiment 1 of the present invention.

  In this printer, toner images of respective color components of yellow (Y), magenta (M), cyan (C), and black (K) are individually formed in the four image forming units 10Y, 10M, 10C, and 10K, and the respective colors. The toner images are primarily transferred so as to be sequentially superimposed on the intermediate transfer belt 20, and then secondarily transferred onto a recording sheet (P) supplied from a sheet feeding device (not shown), and finally recorded on a fixing device (not shown). By performing the fixing process of the upper toner image, a full-color image composed of the four color toners can be formed.

  All of the four image forming units 10 (Y, M, C, K) electronically process toner images obtained by performing image processing on image information input from an externally connected device, a document reading device, etc., and separating the color components into the color components. Individually formed by a photographic process.

  Each of the image forming units 10 includes a photosensitive drum 11 that rotates in the direction of the arrow, a roll-type charging device 12 that contacts and charges the surface of the photosensitive drum 11 (the surface with the photosensitive layer), and the photosensitive drum 11. A latent image exposure device 13 that forms an electrostatic latent image by exposing light beams (dotted arrows) corresponding to the image signals of the respective color components to the charged surface, and a predetermined electrostatic latent image on the photosensitive drum 11. A developing device 14 that develops a toner image by developing with a color developer (toner), a roll-type primary transfer device 15 that transfers the toner image on the photosensitive drum 11 to the intermediate transfer belt 20, and a photosensitive material after the primary transfer. Similarly, a cleaning device 16 for removing toner remaining on the surface of the drum 11 is provided.

  Among these, the developing devices 14Y, 14M, 14C, and 14K of each image forming unit 10 use the two-component developer G including the four-color (nonmagnetic) toner and the (magnetic) carrier exclusively.

  The developing devices 14 (Y, M, C, K) in this example are all opened facing the photosensitive drum 11 and the accommodating portion 41 for accommodating the two-component developer G, as shown in FIGS. And a developing roll 43 is installed in the developing opening 42 of the housing 40, and the developer G is agitated in the accommodating portion 41. Two conveyance augers 44 and 45 for conveyance are installed in a state parallel to the axial direction of the developing roll 43. Further, a trimming member 46 that regulates the layer thickness of the two-component developer G carried on the developing roll 43 (actually the height of the head of the magnetic brush) at a lower side of the developing opening 42 of the housing 40. Is provided. Further, an appropriate amount of developer G is replenished to the accommodating portion 41 of each developing device 14 in a timely manner from a developer replenishing device (not shown).

  The accommodating portion 41 is provided with a partition plate 47 between the two transfer augers 44 and 45 in a state where both end portions thereof are separated from the inner wall surface of the housing 40 by a predetermined distance. It has two accommodating areas 41a and 41b that communicate with each other at both ends. For this reason, in the accommodating part 41, when the developing device 14 is started, the developer G being accommodated is circulated between the accommodating areas 41a and 41b while being stirred by the conveying augers 44 and 45 respectively. To be conveyed. The transport augers 44 and 45 are formed with developer transport blades 44b and 45b that are spirally wound around the rotation shafts 44a and 45b.

  The developing roll 43 is composed of a cylindrical developing sleeve made of stainless steel or the like that is rotationally driven in the direction of the arrow, and a magnet roll that is fixedly installed in the inner space of the developing sleeve and has a plurality of magnetic poles appropriately arranged. ing. Thereby, the two-component developer is carried by forming a magnetic brush on the developing sleeve of the developing roll. The developing sleeve is applied with a developing bias voltage for forming a developing electric field between the developing drum and the photosensitive drum 11 (developing region). Reference numeral 48 in FIG. 2 (FIG. 5) is a seal member for closing the gap between the lower end of the developing opening 42 of the housing 40 and the photosensitive drum 11.

  The intermediate transfer belt 20 is stretched around a plurality of rolls so as to rotate in the direction of the arrow while passing through and contacting the primary transfer position of the photoconductive drum 11 of each image forming unit 10 (position of the primary transfer device 15). is set up. At the secondary transfer position of the intermediate transfer belt 20, a roll-type secondary transfer device 25 for transferring the toner image on the belt onto the recording paper P is disposed in contact with the outer peripheral surface of the belt.

  Further, this printer is equipped with a developer recovery mechanism 50 that recovers a part of the developer G in order to prevent deterioration of the developer G accommodated in each developing device 14 (Y, M, C, K). Has been. Even if a part of the developer G is collected, each developing device 14 is replenished with a new developer from the developer replenishing device and maintained at a predetermined amount.

  The developer recovery mechanism 50 has a leak outlet 51 for naturally overflowing a part of the developer G in the housing portion 41a on the rear side wall surface 40a facing the transport auger 44 of the housing housing portion 41a of each developing device 14. And the leaked developer G ′ leaked from the leak outlet 51 of each developing device 14 is transported through a transport pipe 53 to a recovery box 52 detachably provided in the printer main body and recovered. is there.

The leak outlet 51 has a predetermined opening area (for example, an opening height of 4 to 6 mm, an opening width of 5 to 10 mm, and an opening area of 0.4 cm) at a predetermined height from the bottom of the housing portion 41 a at the center of the housing rear side wall surface 40 a. ² ). The collection box 52 is a container having a volume sufficient to accommodate the leaked developer G ′.

  The transport pipe 53 is a cylindrical pipe, and includes four connection pipe portions 53a that extend directly from the leakage outlet 51 of each developing device 14, and the four connection pipe portions 53a are connected to each other and obliquely downward. The extending pipe portion 53b extends and the upward inclined pipe portion 53c extends obliquely upward from the lower end portion of the collecting pipe portion 53b and extends toward the collection box 52.

  The upward inclined pipe portion 53c is provided with a transport auger 54 for transporting the leaked developer G ′ obliquely upward inside the pipe. The transport auger 54 is formed with a developer transport blade 54 b so as to be spirally wound around the rotation shaft 54 a, and is rotated by the power of the drive motor 55. Further, the connecting portion (terminal portion) of the upward inclined pipe portion 53c with the recovery box 52 is connected to the intake portion 52a on the upper side of the one end portion of the recovery box 52, and is formed on the lower surface portion of the pipe portion 53c. The leaked developer G ′ transported by the transport auger 54 is dropped and discharged from the dropped opening 53d. In FIG. 4, reference numeral 55a denotes a drive shaft, and 52b denotes an inclined dropping surface portion that slides the leaked developer G ′ falling from the dropping port 53d obliquely downward.

  In the developer recovery mechanism 50, as shown in FIG. 5, out of the developer G stored while being replenished in the storage portion 41 of each developing device 14 (Y, M, C, K) during the developing operation. Agitated and transported by the transport auger 44 leaks from the leak outlet 51 as the leaked developer G ′ that is in the state exceeding the leak outlet 51. The leaked developer G ′ is transported so as to slide down to the lower end of the aggregation pipe portion 53b in a state where the leakage developer G ′ is collected by the aggregation pipe portion 53b after dropping each connection pipe portion 53a. Next, the leaked developer G ′ conveyed to the lower end portion of the collecting pipe portion 53b is conveyed by the conveying force of the conveying auger 54 in the upward inclined pipe portion 53c, and then dropped in the vicinity of the end portion of the pipe portion 53d. Then, it falls into the collection box 52 and is collected.

  Further, this printer is equipped with an internal pressure increase suppression mechanism 60A that suppresses an increase in internal pressure of each developing device 14 (Y, M, C, K).

  The internal pressure increase suppression mechanism 60A in this example is a discharge port 61 that discharges excess air generated as the internal pressure of the housing 40 of each developing device 14 (Y, M, C, K) increases. An exhaust passage 62 for exhausting the air to be discharged, an exhaust port 63 for exhausting the air moving through the exhaust passage 62, and a dust removal filter 64 for mainly capturing toner contained in the air exhausted from the exhaust port 63. It consists of and.

  The discharge port 61 is provided in a state where at least a part of the leak port 51 in the housing rear side wall surface portion 40a of each developing device 14 is shared. That is, the outlet 61 opens the upper end of the leak outlet 51 further upward to increase the opening area (specifically, the opening height is increased by about 5 mm and the opening width is increased by about 20 mm). It is formed to function as a discharge port.

  As for the exhaust path 62, the entire section of the transport pipe 53 of the developer recovery mechanism 50 is shared. That is, the exhaust path 62 is configured to cause the connection pipe portion 53a, the aggregation pipe portion 53b, and the upward inclined pipe portion 53c (the ventable area) of the transport pipe 53 to function as the exhaust paths (tubes) 62a, 62b, and 62c. is doing. Among these, the connection pipe portion 53a and the aggregation pipe portion 53b are hollow throughout, and are completely ventilated regions. Further, the upward inclined pipe portion 53c has a space in an internal portion (for example, between the developer conveying blades 54b or between the pipe upper side inner surface and the developer conveying blades 54b) except for the conveying auger 54, and is an air permeable region. Is present.

The exhaust port 63 is opened in the recovery box 52 connected to the end of the transport pipe 53 of the developer recovery mechanism 50. In this example, a predetermined opening area (the transport pipe 53 of the transport pipe 53 is formed on the upper surface of the recovery box 52. The sectional area is about 5 to 10 times larger than 20 cm ² . The dust removal filter 64 can capture at least toner contained in the air that escapes from the exhaust port 63, and is attached in a state of closing the exhaust port 63 opened on the upper surface portion of the collection box 52. Further, the air discharged from the exhaust port 63 having the filter 64 is discharged into the main body of the printer.

  In the internal pressure increase suppression mechanism 60 </ b> A, a ventilation space 49 that connects the developing roll 43 and the discharge port 61 is formed on the upper inner surface 40 b side of the housing 40 of each developing device 14. In this example, the gap is formed between the upper end portion 47 a of the partition plate 47 provided in the housing portion 41 of the housing 40 and the upper inner surface 40 b of the housing 40 so as to ensure air permeability. As a result, air flows smoothly (almost straight) through the ventilation space 49 from the developing roll 43 side to the discharge port 61 side without any obstruction (not blocked by the partition plate 47, the developer G, etc.). It has become.

  Next, the operation (function) of the internal pressure increase suppression mechanism 60A will be described.

  First, as shown in FIG. 5, the internal pressure rises when the developing roll 43 is rotated in the direction of the arrow in the developing opening 42 of the housing 40 of each developing device 14 during printing (image forming operation). Excess air (E) generated by the increase in internal pressure flows to the discharge port 61 side opened through the ventilation space 49 on the upper inner surface 40 b side of each housing 40 and is discharged from the discharge port 61. . At this time, the air (E) is smoothly and substantially straight without any obstacles such as being blocked by the partition plate 47 or the developer G from the developing roll 43 side to the discharge port 61 side due to the presence of the ventilation space 49. Flowing.

  Subsequently, the air (E) individually discharged from the discharge port 61 of each developing device 14 flows into the aggregation pipe portion 53b through the connection pipe portion 53a and is collected by the pressure due to the internal pressure thereof. Then, it flows so as to pass through the gap with the transfer auger 54 in the upward inclined pipe portion 53c, and flows into the collection box 52 from the drop port 53d in the vicinity of the end portion of the pipe portion.

  The air (E) flowing to the collection box 52 finally passes through the filter 64 from the exhaust port 63 at the top of the collection box 52 and is discharged to the outside (actually, the internal space of the printer main body). At this time, since the toner contained in the air (E) is captured by the filter 64, the discharged air does not cause toner contamination.

  In this way, excess air (E) generated by the increase in internal pressure of each developing device 14 is exhausted by the internal pressure increase suppression mechanism 60A, so that the increase in internal pressure is suppressed, and as a result, the increase in internal pressure is suppressed. Toner scattering in the development area, which was the cause of occurrence, is also prevented. Thus, the adverse effect on the printed image due to the toner scattering and the problem of toner contamination inside the printer do not occur.

  Further, in the internal pressure increase suppression mechanism 60A, the exhaust port 63 and the filter 64 are formed in the recovery box 62 having a larger upper surface area than the developing device 14 (housing 40) with a wide opening area. The life of the filter 64 also becomes longer in proportion to the filter area, and as a result, the interval of maintenance work for replacement and cleaning of the filter 64 becomes longer.

  Furthermore, since the filter 64 has a long service life, since the entire section of the transport pipe 53 having a bent portion is shared as the air passage 62, the air travel distance becomes long, and the air strikes at the bent portion. The advancement facilitates the natural separation and dropping of the toner contained in the air during the movement, resulting in a decrease in the amount of toner reaching the filter 64. In addition, since the transport auger 54 is installed in the upward inclined pipe portion 53c, the air moving through the pipe portion 53c travels while hitting the transport blade 54b of the transport auger 54 so as to hit the transport blade 54b. This is also caused by the amount of toner that reaches the filter 64 being reduced as a result of the contained toner falling.

  In the internal pressure increase suppression mechanism 60A, the discharge port 61, the air passage 62, the exhaust port 63, and the like are configured by sharing and using the leakage port 51, the transport pipe 53, the recovery box 52, and the like in the developer supply mechanism 50. Therefore, an increase in internal pressure in the four developing devices 14 can be efficiently suppressed with a simple configuration without causing a significant increase in installation space and cost.

[Embodiment 2]
FIG. 6 shows the main part (further part) of the color printer according to Embodiment 2 of the present invention.

  This printer has the same configuration as the printer according to the first embodiment except that an internal pressure increase suppression mechanism 60B obtained by changing a part of the internal pressure increase suppression mechanism 60A according to the first embodiment is applied. For this reason, in FIG. 6, the same reference numerals are given to the parts common to the printer according to the first embodiment, and the description of the common components is omitted in the following (this). The same applies to the following embodiments).

  As shown in FIG. 6, the internal pressure rise suppression mechanism 60B is connected to the upward inclined pipe portion 53c of the transport pipe shared as the exhaust path 62 with respect to the exhaust port 63 and the dust removal filter 64. 63 is different from the internal pressure increase suppression mechanism 60 </ b> A in the first embodiment only in that a dust removal filter 64 is provided at the exhaust port 63. In the internal pressure increase suppression mechanism 60B, the exhaust port 63 and the dust removal filter 64 are not provided in the collection box 52 due to the relationship with the change point.

  The exhaust unit 65 is composed of an exhaust box 65b in which an upper surface part in the middle of the upward inclined pipe part 53c is opened and connected by a connecting pipe 65a. The exhaust box 65 b has an internal space whose horizontal sectional area is larger than the sectional area of the transport pipe 53. The exhaust port 63 is opened on the upper surface of the exhaust box 65b. The opening area of the exhaust port 63 is larger than the cross-sectional area of the transport pipe 53. The dust removal filter 64 is attached so as to close the exhaust port 63 having such an opening area.

  Such an internal pressure increase suppression mechanism 60B operates (functions) basically in the same manner as the internal pressure increase suppression mechanism 60A in the first embodiment except for the points described below.

  That is, as shown in FIG. 6, the air (E) generated by the internal pressure increase of each developing device 14 (Y, M, C, K) is discharged from the discharge port 61 of each housing 40 and is connected to each connecting pipe portion. An exhaust unit 65 that flows through the gap with the conveying auger 54 in the upward inclined pipe portion 53c via the 53a and the collecting pipe portion 53b and is opened and connected to the middle portion of the pipe portion 53c. Into the exhaust box 65b.

  Then, the air that has flowed to the exhaust unit 65 finally passes through the filter 64 from the exhaust port 63 on the upper surface of the exhaust box 65b and is discharged to the outside (actually, the internal space of the printer main body).

  Further, in this internal pressure increase suppression mechanism 60B, in particular, the distance from the discharge port 61 to the exhaust port 63 as compared with the internal pressure increase suppression mechanism 60A in the first embodiment (a configuration in which the internal pressure increase suppression mechanism 60A is exhausted by moving to the recovery box). Since the excess air (E) discharged from the discharge port 61 is directed toward the exhaust port 63 provided in the exhaust unit 65 installed at a position close to the discharge port 61, it is favorable in a state where there is little pressure loss. It can be exhausted. Also in this case, since the exhaust port 63 is provided in a separate exhaust unit 65 different from the transport pipe 53, the exhaust port 63 is provided as an exhaust port having an opening area wider than the cross-sectional area of the transport pipe 53. Accordingly, the filter 64 having a large area can be used correspondingly, so that the life of the filter 64 can be extended.

  In the second embodiment, instead of installing the exhaust unit 65, the exhaust port 63 is directly connected to the part of the transport pipe 53 (the aggregated pipe part 53b, the upward inclined pipe part 53c, etc.) shared as the ventilation path 62. And a dust removal filter 64 may be provided at the exhaust port 63. In this case, the air (E) discharged from the discharge port 61 of each developing device 14 is finally exhausted through the exhaust port 63 and the filter 64 opened in the part of the transport pipe 53. .

[Embodiment 3]
FIG. 7 shows the main part (further part) of the color printer according to Embodiment 3 of the present invention.

  This printer has the same configuration as the printer according to the first embodiment except that an internal pressure increase suppression mechanism 60C obtained by changing a part of the internal pressure increase suppression mechanism 60A in the first embodiment is applied.

  As shown in FIG. 7, the internal pressure rise suppression mechanism 60C is implemented in that a ventilation pipe 66 different from the transport pipe 53 is specially installed as an exhaust path 62 in a section corresponding to the upward inclined pipe portion 53c. Only the internal pressure increase suppression mechanism 60A in the first embodiment is different. The ventilation pipe 66 is installed on the upper side of the upward inclined pipe portion 53c in a state parallel to the pipe portion. The ventilation pipe 66 is opened at the start end portion 66a side to communicate with the aggregation pipe portion 53b and the end portion 66b. The side is opened and communicated with the end portion of the ascending inclined pipe portion 53c where the drop port 52a is located.

  Such an internal pressure increase suppression mechanism 60C operates (functions) basically in the same manner as the internal pressure increase suppression mechanism 60A in the first embodiment except for the points described below.

  That is, as shown in FIG. 7, the air (E) generated by the increase in internal pressure of each developing device 14 (Y, M, C, K) is discharged from the discharge port 61 of each housing 40 and is connected to each connecting pipe portion. 53a and the aggregation pipe portion 53b, and then flows through the ventilation pipe 66 instead of the upward inclined pipe portion 53c, and then passes through the upward inclined pipe portion 53c at the end 66b of the pipe from the drop port 52a to the inside of the recovery box 52. Flow into. Incidentally, the air that has flowed to the collection box 52 at this time is finally discharged from the exhaust port 63 on the upper surface of the collection box 52 through the filter 64 to the outside (actually, the internal space of the printer main body).

  In addition, the internal pressure rise suppression mechanism 60C is a transport pipe section that is difficult to function as an exhaust path because the upward inclined pipe portion 53c has a small air-permeable region due to the presence of the transport auger 54 and is easily filled by toner accumulation. Therefore, by providing a dedicated ventilation pipe 66 corresponding to the section of the inclined conveying pipe 53, it becomes possible to ensure a good exhaust function of the exhaust air (E) in the corresponding section. An increase in internal pressure can be suppressed satisfactorily.

[Embodiment 4]
FIG. 8 shows the main part (further part) of the color printer according to Embodiment 4 of the present invention.

  This printer has the same configuration as the printer according to the first embodiment except that an internal pressure increase suppression mechanism 60D obtained by changing a part of the internal pressure increase suppression mechanism 60A according to the first embodiment is applied.

  As shown in FIG. 8, the internal pressure increase suppression mechanism 60 </ b> D branches from the connection pipe portion 53 a of the developing device 14 </ b> Y disposed on the upper side and installs a ventilation pipe 67 different from the conveyance pipe 53 as an exhaust path 62 exclusively. Only the difference from the internal pressure increase suppression mechanism 60A in the first embodiment is that the change is made as described above. The ventilation pipe 67 is installed as a bypass-type ventilation path so as to be a bypassed ventilation path different from the conveyance pipe 53, and the start end portion 67a side is opened to branch from the connection pipe portion 53a. The end portion 66b is opened and communicated with the inside of the collection box 52.

  Such an internal pressure increase suppression mechanism 60D operates (functions) basically in the same manner as the internal pressure increase suppression mechanism 60A in the first embodiment except for the points described below.

  That is, as shown in FIG. 8, the air (E) generated by the internal pressure increase of each developing device 14 (Y, M, C, K) is discharged from the discharge port 61 of each housing 40 and is connected to each connecting pipe portion. After flowing into the ventilation pipe 67 directly from 53a or via the aggregation pipe portion 53b, it flows into the collection box 52 at the end portion 67b of the pipe. Incidentally, the air that has flowed to the collection box 52 at this time is finally discharged from the exhaust port 63 on the upper surface of the collection box 52 through the filter 64 to the outside (actually, the internal space of the printer main body). Further, the air (E) discharged from the discharge port 61 of the developing device 14 (M, C, K) disposed on the second and subsequent lower side is in a state where the air permeability of the upward inclined pipe portion 53c is poor. Since the air naturally flows to the path side having good air permeability, the air also flows to the air pipe 67 side.

  In addition, the internal pressure increase suppression mechanism 60D is a transport pipe section that is difficult to function as an exhaust path because the upward inclined pipe portion 53c has a small air-permeable region due to the presence of the transport auger 54 and is easily filled by toner accumulation. In this case, by providing a dedicated bypass-type ventilation pipe 67 directly connected to the collection box 52 without passing through the inclined conveying pipe 53, good exhaust of exhaust air (E) in the corresponding section is provided. A function can be secured, and as a result, an increase in internal pressure can be satisfactorily suppressed.

[Other embodiments]
In the first to fourth embodiments, the case where the conveyance pipe 53 of the developer supply mechanism 5 has an upward inclined pipe portion 53c that becomes an upward inclined section is illustrated. For example, the lower end portion of the aggregation pipe portion 53b is used. If the collection box 52 can be directly connected first, it is not necessary to install the transfer auger 54 at all. In this case, the air passage 62 in the internal pressure rise suppression mechanism 60 can also be configured with the content that the transport auger 54 does not exist.

FIG. 3 is an explanatory diagram illustrating a main part of the printer according to the first embodiment. It is a schematic longitudinal cross-sectional view which shows structures, such as a developing device and an internal pressure raise suppression mechanism. FIG. 3 is a schematic cross-sectional view of the developing device of FIG. 2 and an internal pressure increase suppression mechanism and the like. It is explanatory drawing which shows the upper surface state and QQ line cross-sectional state of a part (collection | recovery part and exhaust part) of a developer supply mechanism and an internal pressure raise suppression mechanism. It is a schematic explanatory drawing which shows a structure and operation state of a developing device, an internal pressure rise suppression mechanism, etc. FIG. 10 is an explanatory diagram illustrating a main part (part of: particularly another configuration of an internal pressure increase suppression mechanism) of a printer according to a second embodiment. FIG. 10 is an explanatory diagram illustrating a main part (part of: particularly another configuration of an internal pressure increase suppression mechanism) of a printer according to a third embodiment. FIG. 10 is an explanatory diagram showing a main part (part of: another configuration of an internal pressure increase suppression mechanism in particular) of a printer according to a fourth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 14 ... Development apparatus, 40 ... Housing (development container), 41 ... accommodating part, 42 ... development opening, 43 ... developing roll (developer carrier), 44,45 ... conveying auger (stirring conveying member) Ventilation space 51 ... leakage outlet 52 ... collection box (collection container) 53 ... conveying pipe (conveying pipe) 53c ... ascending inclined pipe part (ascending inclined part of conveying pipe) 54 ... conveying auger (rotary conveying member) ), 54b ... Conveying blades, 61 ... Discharge port, 62 ... Vent passage, 63 ... Exhaust port, 64 ... Dust-proof filter, 65 ... Exhaust unit, 66, 67 ... Ventilation pipe (exhaust pipe), G ... Two-component developer (Developer including toner and carrier), G '... Leakage developer, E ... Exhaust air (excess air generated by increasing internal pressure).

Claims (7)

A developer container in which a developer containing toner and a carrier is accommodated, a developing container in which a developing opening is formed, an agitating and conveying member that conveys the developer accommodated in the accommodating part of the developer container, and the agitation A developer carrying member that is provided in the developing opening of the developing container and rotates so as to carry the developer stirred by the carrying member and carry it to the developing region, and the developing container that surrounds the stirring and carrying member A developing device having a leak outlet for leaking a part of the developer provided in the storage portion of
A collection container for collecting the leaked developer leaked from the leak port of the developing device;
An image forming apparatus including a recovery pipe connected between the recovery container and the leak outlet and transporting the leaked developer to the recovery container,
A discharge port for discharging excess air generated as the internal pressure of the developer container increases is provided in a state in which at least a part of the leakage port is shared, and an exhaust path for discharging the air discharged from the discharge port is conveyed An image forming apparatus characterized in that at least a partial section of a tube is shared.   The image forming apparatus according to claim 1, wherein a ventilation space that connects between the developer carrier and the discharge port is formed on an upper inner surface side of a developing container in the developing device.   The image forming apparatus according to claim 1, wherein an exhaust port is provided in the collection container, and a dust removal filter is attached to the exhaust port.   The exhaust port is provided in a part of a transport pipe shared as the exhaust path or an exhaust unit connected to the transport pipe, and a dust removal filter is attached to the exhaust port. Image forming apparatus.   5. The image forming apparatus according to claim 1, wherein a rotation conveyance member having a helical conveyance blade that conveys the leaked developer is installed in a part of a conveyance pipe shared as the exhaust path.   The image forming apparatus according to claim 1, wherein a part of the exhaust path is configured by a vent pipe different from the transport pipe.   The image forming apparatus according to claim 6, wherein a ventilation pipe as an exhaust path different from the conveyance pipe is provided in an area corresponding to an upward inclined section in which the leakage developer is conveyed obliquely upward in the conveyance pipe. .

Images