JP5332718B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus, and more particularly to a two-component developer supply mechanism.

  In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a printing machine, an electrostatic latent image formed on a photosensitive member as a latent image carrier is subjected to visible image processing by a developing device, and the visible image is converted into a sheet. A recording output can be obtained by transferring to the above.

  As a developer used for development, there is a two-component developer obtained by mixing a toner and a carrier in addition to a one-component developer containing only a magnetic or non-magnetic toner.

  The two-component developer is composed of a toner and a carrier that carries the toner, and the toner can be electrostatically attracted to the electrostatic latent image on the photosensitive member by charging the toner by a frictional charging effect that occurs during stirring and mixing. It is said.

  The developing device includes a developing sleeve for supplying a developer toward the electrostatic latent image on the photosensitive member by causing the developer to rise on the peripheral surface by magnetic force, and an agitation for supplying the developer mixed with stirring to the developing sleeve. A configuration including a sleeve is known, and a developer in which toner is consumed for visible image processing of an electrostatic latent image on a photoreceptor is collected by a developing device.

  On the other hand, the developing device includes a supply member that supplies the developer along the axial direction of the developing sleeve while transporting each plate to the developing sleeve described above, and the developer that has passed through the developing region in the developing sleeve. There is a configuration in which a recovery member for recovering the water is arranged with its axial direction parallel (for example, Patent Document 1).

  In the above-mentioned patent document, a screw auger having a spiral blade in the axial direction is used as a supply member and a recovery member, and a supply member and a recovery member in which a screw auger is used in addition to a developing sleeve (hereinafter, these members are referred to as a supply screw). And a recovery screw) are disposed in the space of the developing tank, and a developer conveying path is configured in the developing tank.

  In the developing device having such a configuration, when the developer concentration is lowered, when the toner is replenished, the developer screw is agitated and conveyed in the axial direction by the supply screw and the recovery screw so that the developer concentration is stabilized. It has become.

  The developer in the developing tank is sent to the recovery screw when it passes through the development area for visible image processing, and when density stabilization is necessary, it is sent to the supply screw after receiving toner replenishment. .

  By the way, when the developer is agitated and transported along the axial direction of the supply screw, the bulk differs between the upstream side and the downstream side in the moving direction because the developer moves to the developing sleeve side during the moving process. In particular, the bulk decreases on the downstream side in the movement direction.

  For this reason, on the downstream side of the developer moving direction, the amount of developer transport is reduced, so the chance of exposing the blade of the screw increases. Or a portion where only a small amount of developer is present at the tip of the blade is repeated to face the developing sleeve, which easily causes unevenness in which a certain amount of developer cannot be supplied.

  By the way, as a system for supplying the developer to the developing sleeve, a system in which the developer is pumped by a magnetic force and carried on the surface of the sleeve, and a system in which the developer moving from the supply screw overflows from a part of the wall toward the developing sleeve (overflow). There is.

  Among these methods, in the case of the method of causing the developer to overflow, it is assumed that the developer overflowed and spilled with respect to the method of pumping up by the magnetic force is in contact with the surface of the developing sleeve. In contrast, the developer carrying amount on the surface of the developing sleeve is smaller than the method of supplying the developer. However, because it is not forced suction by magnetic force, the amount of developer related to the doctor blade that defines the development layer thickness is not large, so that developer condensation is unlikely to occur when facing the doctor blade. There is a small advantage to stress.

  Therefore, as a configuration for preventing the decrease of the developer on the downstream side in the developer moving direction, the developer tank 1002 as shown in FIG. 11 is targeted for a method of supplying the overflowing developer to the surface of the developing sleeve. The shape of the dam portion 1002A corresponding to the position where the developer overflows in a part of the wall portion provided in the developer moves in accordance with the volume of the developer on the upstream side and the downstream side in the developer moving direction. There is a configuration in which the height of the wall portion on the downstream side in the direction is lowered (a configuration in which H1> H2 in FIG. 11 as a relationship between reference characters H1 and H2), and the amount of developer present at that position is increased. It has been proposed (for example, Patent Document 2). In FIG. 11, reference numeral 1000 denotes a developer conveying screw, and reference numeral 1001 denotes a developing sleeve which is a developing carrier. FIG. 11A shows the shape of the wall portion 1002A viewed from the developing sleeve 1001 side.

  On the other hand, as a configuration of the developing device, a developer layer provided with a developing sleeve and a stirring screw as a developer supply portion, and when the developer is collected from the developer tank and replenished with toner, this is put into the developer. There is a configuration in which the developer is conveyed by airflow in a configuration in which the developer is stirred and conveyed toward the developing layer (for example, Patent Document 3).

  If the height of the weirs on the upstream and downstream sides in the developer movement direction is different on the assumption that the developer overflows, the volume of the developer changes depending on the developer concentration and the state of deterioration. Therefore, a change in the constant height cannot cope with the change in the bulk due to the change in the developer characteristics. For this reason, the problem that the uneven supply of the developer occurs due to the developer concentration and the deterioration state still remains.

  On the other hand, in the configuration using airflow conveyance, the amount of developer supplied to the developing sleeve is controlled by the amount of airflow, so that it is extremely difficult to control, and when using a two-component developer, the toner alone is used. Unlike the case of a one-component developer, the specific gravity is large, and a considerable air flow rate and pressure are required to transport the developer. For this reason, there exists a possibility that an apparatus may be enlarged including the pump for airflow conveyance.

  An object of the present invention is to suppress the uneven supply of the developer, that is, the uneven supply of the developer corresponding to the blade pitch of the screw, and to convey the developer in the air flow, in view of the problems in the conventional developing device. Another object of the present invention is to provide a developing device having a configuration capable of preventing scattering in the case of the above and an image forming apparatus using the developing device.

In order to achieve this object, the present invention comprises the following arrangement.
(1) A developer carrying member capable of carrying on the surface a developer for visual image processing of an electrostatic latent image on the latent image carrying member, and positioned above and above the developer carrying member, A developer conveying member that supplies the developer to the developer carrying member while conveying the developer in the direction, a developer collecting member that collects the developer after development, the developer conveying member, and the developer carrying member, in the developing device provided with a current image tank capable of accommodating a developer therein has a wall portion between,
The wall portion in the developing tank is formed with an opening that communicates the inside of the developing tank and the developer carrier, and the developer is discharged by gravity through the opening .
The developing device is characterized in that the opening is positioned on a straight line when axes of the developer conveying member, the developer carrying member, and the developer collecting member are located on a straight line .
(2) The developing device according to (1), wherein the opening is positioned below a developer surface in which the developer conveying member is buried.
(3) The developing device according to (1) or (2), wherein the opening is positioned above a straight line connecting the axes of the developer conveying member and the developer carrier. .
(4) A developer carrying member capable of carrying on the surface a developer for visual processing of an electrostatic latent image on the latent image carrying member, and positioned in the vicinity of the upper portion of the developer carrying member. A developer conveying member that supplies the developer to the developer carrying member while conveying the developer in the direction, a developer collecting member that collects the developer after development, the developer conveying member, and the developer carrying member, A developing device having a wall portion between and a developing tank capable of accommodating a developer therein,
The wall portion in the developing tank is formed with an opening that communicates the inside of the developing tank and the developer carrier, and the developer is discharged by gravity through the opening.
The developing device according to claim 1, wherein a plurality of the openings are arranged along a rotation direction of the developer conveying member .
(5) A developer carrying member capable of carrying on the surface a developer for visual image processing of the electrostatic latent image on the latent image carrying member, and positioned in the vicinity of the upper portion of the developer carrying member. A developer conveying member that supplies the developer to the developer carrying member while conveying the developer in the direction, a developer collecting member that collects the developer after development, the developer conveying member, and the developer carrying member, A developing device having a wall portion between and a developing tank capable of accommodating a developer therein,
The wall portion in the developing tank is formed with an opening that communicates the inside of the developing tank and the developer carrier, and the developer is discharged by gravity through the opening.
2. A developing apparatus according to claim 1, wherein a carrier air flow inlet for introducing a developer carrier air flow is connected in the vicinity of the developer supply position, and an air vent is provided in the vicinity of the developer supply position .
(6) The width of the opening is wider than the layer thickness set by a developing layer thickness regulating member provided in the developing tank. (1) to (5) the developing device according to any one of the five.
(7) The developing device according to ( 5 ), wherein the air bleeding portion is provided at a position higher than an installation position of the developer conveying member .
(8) The wall surface facing the developer transport member in the developer tank wall portion is shaped to follow the outer shape of the developer transport member, and the gap between the developer transport member and the developer transport member is set to 1.5 mm. an apparatus according to any one of to, characterized in that is (1) to (7).
(9) An image forming apparatus using the developing device according to any one of (1) to (8) .

  According to the present invention, since the opening through which the developer is discharged by gravity is provided, unlike the case where the developer overflows, it is possible to supply the developer using continuous free fall of the developer. Thereby, supply unevenness can be eliminated.

  Further, when using the movement of the developer image by the conveying airflow, since the air bleeding portion is provided in the vicinity of the developer supply position, a member for regulating the developer layer thickness is provided at the developer supply position. In this case, it is possible to suppress the increase in internal pressure when the conveying airflow hits the regulating member, and to prevent the developer from scattering due to the increase in internal pressure.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus in which a developing device according to an embodiment of the present invention is used. 1 is a schematic diagram for explaining an overall configuration of a developing device according to an embodiment of the present invention. FIG. 3 is a schematic diagram for explaining a configuration of a developing unit in the developing device shown in FIG. 2. FIG. 3 is a schematic diagram for explaining an internal configuration of a developer container used in the developing device illustrated in FIG. 2. It is a schematic diagram showing one of the main components of the developing device according to the embodiment of the present invention. It is a schematic diagram for demonstrating the characteristic of the principal part structure shown in FIG. It is a schematic diagram for demonstrating another characteristic regarding the principal part structure shown in FIG. It is a schematic diagram for demonstrating the other characteristic regarding the principal part structure shown in FIG. It is a schematic diagram for demonstrating the characteristic which coped with the airflow conveyance structure of the developing device by embodiment of this invention. It is a schematic diagram for demonstrating the other characteristic of the developing tank used for the image development apparatus by embodiment of this invention. It is a schematic diagram for demonstrating the prior art example of a developing device.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to embodiments shown in the drawings.

  FIG. 1 is a schematic diagram for explaining the configuration of an image forming apparatus using a developing device according to the present invention.

  An image forming apparatus 1000 shown in FIG. 1 is made to correspond to each color (yellow, magenta, cyan, black) facing the lower surface of an intermediate transfer belt 10A used as an intermediate transfer unit 10 as an unfixed image carrier. Image portions 6Y, 6M, 6C, and 6K are juxtaposed. These image forming units 6Y, 6M, 6C, and 6K have the same structure except that the color of the toner used in the image forming process is different. In the following description, only the numerical symbols common to the image forming units will be described, and the alphabetic symbols indicating the toner colors will be omitted.

  Each image forming unit 6 includes a photosensitive drum 1 as a latent image carrier, a charging unit 2, a developing device 3, a cleaning unit 4 and the like disposed around the photosensitive drum 1.

  An image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1, and a desired toner image is formed on the photosensitive drum 1.

  The photosensitive drum 1 is rotationally driven in the clockwise direction in the drawing by a driving unit (not shown), and the surface is uniformly charged at the position of the charging means 2 (charging process).

  The surface of the photosensitive drum 1 reaches an irradiation position of a laser beam emitted from an exposure unit (not shown), and an electrostatic latent image is formed by exposure scanning at this position (exposure process). When the position reaches this position, the visible image is processed by the toner contained in the developer supplied from the position, and the development process is executed.

  The surface of the photosensitive drum 1 carrying the toner image that has been processed into a visible image in the developing process reaches a position facing the intermediate transfer belt 10A and the primary transfer bias roller 5, and on the photosensitive drum 1 at this position. The toner image is transferred onto the intermediate transfer belt 10A (primary transfer step).

  After the transfer, the surface of the photosensitive member 1 reaches a position facing the cleaning unit 4, and untransferred toner remaining on the photosensitive drum 1 is collected at this position (cleaning step). After cleaning, the potential of the surface of the photosensitive drum 1 is initialized by a neutralizing roller (not shown). By passing through such steps, a series of image forming processes performed on the photosensitive drum 1 is completed.

  The image forming process described above is performed at the time of forming a single image of only a monochrome image and at the time of forming a full color image. At the time of forming a full color image, each of the four image forming units 6Y, 6M, 6C, and 6K shown in FIG. Each step is performed. That is, a laser beam based on image information from an exposure unit (optical writing device) (not shown) disposed below the image forming unit is applied to the photosensitive drums of the image forming units 6Y, 6M, 6C, and 6K. Irradiated toward. Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 8 in an overlapping manner. Thus, a color image is formed on the intermediate transfer belt 10A.

  The four primary transfer bias rollers 5Y, 5M, 5C, and 5K respectively sandwich the intermediate transfer belt 10A with the photosensitive drums 1Y, 1M, 1C, and 1K to form a primary transfer nip. The primary transfer bias rollers 5Y, 5M, 5C, and 5K are applied with a transfer bias having a polarity opposite to the polarity of the toner.

  The intermediate transfer belt 10A travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 5Y, 5M, 5C, and 5K. Thus, the toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1K are primarily transferred while being superimposed on the intermediate transfer belt 10A.

  The intermediate transfer belt 10A onto which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 7 as a secondary transfer unit. The color toner image formed on the intermediate transfer belt 10A is collectively transferred onto a transfer sheet P as a recording medium conveyed to the secondary transfer nip position.

  A plurality of transfer sheets P are stored in the paper supply unit 8 disposed in the lower part of the apparatus main body 1000 and are separated and fed one by one by a paper supply roller 9. The fed transfer paper P is temporarily stopped by the registration roller pair 10, and after the oblique deviation is corrected, it is conveyed toward the secondary transfer nip by the registration roller pair 10 at a predetermined timing. As described above, a desired color image is transferred onto the transfer paper P at the secondary transfer nip.

  The transfer paper P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the fixing unit 11 where the color image transferred to the surface is fixed by heat and pressure generated by the fixing roller and the pressure roller. The

  After the fixing, the transfer paper P is discharged as an output image to the paper discharge unit 1000A formed on the upper surface of the apparatus main body 100 by the paper discharge roller pair 12 and stacked. Thus, a series of image forming processes in the image forming apparatus is completed. In FIG. 1, reference numeral 13 denotes a cleaning device for the intermediate transfer belt 10A.

  Next, the configuration of the developing device according to the present invention will be described.

  FIG. 2 is a diagram showing the overall configuration of the developing device according to the present invention.

  In FIG. 2, the developing device will be described in detail later. A developing unit that executes a developing process with a two-component developer in which a carrier and a toner are mixed with a photosensitive drum, and a developer collected from the developing unit. A circulation unit that transports the developer again toward the developer supply unit of the development unit is provided.

  In FIG. 2, the developing device 3 includes a developing tank 30 that can store a developer for developing the electrostatic latent image on the photosensitive drum 1, a developer collected from the developing tank 30 at a position away from the developing tank 30, and Developer container 40 that stirs and mixes new toner that matches the consumed toner, toner tank 61 that replenishes new toner toward developer container 40, and development after stirring and mixing discharged from developer container 40 A rotary feeder 50 for transferring the developer, an air pump 51 corresponding to a developer circulation drive source for transferring the developer toward the developing tank 30 by air pressure, and a new toner is supplied to the developer accommodating portion 40. A toner supply unit 60 and the like are provided. In FIG. 1, the developing tank 30 is configured in a cartridge shape.

  The developer tank 30 and the developer container 40 are connected by a developer recovery channel 41 and a rotary feeder 50 connected from the inside of the developer tank 30 and a developer supply channel 42 connected to the upper part of the developer tank 30. Thus, a developer circulation path is formed, and a circulation portion is formed by members provided in the circulation path.

  The developer supply flow path 42 connected to the developing tank 30 is connected so as to face one end in the axial direction of the conveying screw 32 (see FIG. 3) as described in FIG. 3. Further, the developer recovery channel 41 is located at a position opposite to the side to which the developer supply channel 42 is connected in the axial direction of the other conveying screw 33 (see FIG. 3) provided in the developer tank 30. It is connected.

  The developer accommodating portion 40 has an appearance like a silo with an upper portion in a cylindrical shape and a lower portion in a downward conical shape, and a stirring member described in the features of this embodiment is provided inside. . A driving motor 40 </ b> A that forms a driving unit for the stirring member and a torque sensor 40 </ b> B that detects the rotational torque of the stirring member are provided on the upper portion of the developer storage unit 40.

  The developer agitated and mixed in the developer accommodating portion 40 is fed to a rotary feeder 50 that is provided with a paddle capable of adjusting the supply amount and is rotationally driven by a drive motor 50A, and the supply amount is adjusted at this position. The developer is conveyed toward the developing tank 30 by the air flow generated by the air pump 51.

  The toner supply unit 60 includes a toner tank 61, a toner supply path 62 connected between the toner tank 61 and the developer container 40, and a conveying member such as a screw auger disposed in the toner supply path 62. And a drive motor 63 for driving (not shown).

  The internal structure of the developing tank 30 is shown in FIG.

  In FIG. 3, in the developing tank 30, a developing sleeve 31 that bears a developer facing the photosensitive drum 1, and a conveying screw that is disposed in the vicinity of the developing sleeve 31 and has an opposite lead direction set. 32 and 33, and a doctor blade 34 that defines the amount of developer carried on the surface of the developing sleeve 31 in the vicinity of the developer supply position. In the present embodiment, the conveying screw 32 functions as a developer conveying member for supplying the developer toward the developing sleeve 31, and the conveying screw 33 functions as a collection conveying member that collects the developer after development. Therefore, in the following description, reference numeral 32 is expressed as a developer conveying screw, and reference numeral 33 is expressed as a developer recovery screw.

  The developer in the developing tank 30 is conveyed from the front side to the rear side in FIG. 3 by the developer conveying screw 32 and the developer collecting screw 33, and a part of the developer is sucked up by the magnetic force in the developing sleeve 31 and is adsorbed. Then, after being uniformed to a uniform thickness by the doctor blade 34, the electrostatic latent image on the photosensitive drum 1 is developed with toner by contacting the photosensitive drum 1, and a toner image is formed.

  The developed developer is transported to the developer accommodating section 40 from a developer recovery channel 41 (see FIG. 2) connected to the end of the transport screw 33.

  A toner density detecting means (not shown) is installed on the most downstream side of the conveying screw 33, and new toner is replenished from the toner tank 61 based on the signal. As described above, the replenishment of the toner is performed via the conveying screw disposed in the developer supply path 41.

The configuration of the developer container 40 described above is shown in FIG.
In FIG. 4, the developer container 40 is provided with a paddle wheel 42 having a plurality of stirring blades 42 </ b> A that are rotationally driven by a motor 40 </ b> A. The toner and carrier that are stirred and mixed by the paddle wheel 42 are supplied to the developer container 40. And the developer is introduced into the rotary feeder 50 connected to the lower part.

  The rotary feeder 50 is equipped with a rotor 501 having a plurality of blades 501A and a stator 502 that covers the rotor 501A. The roller 501 is driven to rotate by the motor 50A, thereby delivering a predetermined amount of developer scooped by the blades. It is like that.

  The developer fed from the rotary feeder 50 is transported to the developing tank 30 side by the transport airflow supplied from the air pump 51.

Next, features of the developing device 3 used in the image forming apparatus having the above configuration will be described.
FIG. 5 is a schematic view showing one of the features of the developing device according to the present invention. The feature shown in FIG. A slit 100 used as an opening communicating with the side is provided so that the developer is discharged by gravity.

  The slit 100 has a length in the longitudinal direction corresponding to the axial length of the developer conveying screw 32, and is formed at a position facing the developing sleeve 31 as shown in FIGS. ing. That is, the slit 100 is provided below the developer surface in the space where the developer conveying screw 32 is formed by the wall portion 30 </ b> A in the developing tank 30 in which the developer conveying screw 32 is buried. As a result, the developer is discharged by free fall due to gravity.

  FIG. 5A shows the state of the slit 100 in the wall portion 30A when viewed from the developing sleeve 31 side.

  The width corresponding to the direction perpendicular to the longitudinal direction of the slit 100 is formed with the same width on both the upstream side and the downstream side in the moving direction of the developer moving along the axial direction of the developer conveying screw 32.

  In this configuration, even when the amount of the developer changes on the upstream side and the downstream side where the developer moves by the developer conveying screw 32, the slit 100 is not overflowed but is freely dropped by gravity of the developer itself. As a result, the developer can be continuously supplied. This prevents uneven supply that occurs when the amount of developer is reduced during transportation using a screw. Can do.

  Regarding the configuration of the slit 100, the following conditions are set.

  As a first setting condition, as shown in FIG. 6A, the installation position of the slit 100 is positioned above a straight line L connecting the axial centers of the developing sleeve 31 and the developer conveying screw 32. .

  This is intended to cause the developer discharged from the slit 100 to pour onto the peripheral surface of the developing sleeve 31.

  That is, when the slit 100 is positioned below the straight line L described above, the developer discharged from the slit 100 is likely to pass through the side of the peripheral surface of the developing sleeve 31 as it is. This prevents the development sleeve 31 from staying on the peripheral surface. Accordingly, the developer can be supplied without waste even on the downstream side in the moving direction of the developer, and the supplied developer is reliably carried on the peripheral surface of the developing sleeve 31.

  As the second setting condition, as shown in FIG. 6B, the developer conveying screw 32, the developing sleeve 31, and the developer collecting screw 33 are respectively provided as the configuration of the developing device (denoted by reference numeral 30 ′ for convenience). When the axial center is positioned on a straight line (state indicated by reference sign L in FIG. 6B), the slit 100 is positioned on the straight line.

  With respect to this positioning, as described above, the developer is discharged from the slit 100 so that the developer can easily fall onto the peripheral surface of the developing sleeve 31.

  In the developing device of the present invention, since the developer is transported using the transport airflow, the developer can be transported even when the arrangement structure of each member as shown in FIG. As a result, the size of the developing device in the width direction can be reduced. Even in this case, the developer can be supplied without causing uneven supply regardless of the decrease in the developer amount downstream in the developer moving direction. can do.

  As a third setting condition, a width corresponding to a direction perpendicular to the longitudinal direction of the slit 100 is formed by a gap between the doctor blade 34 (see FIG. 3) as a developing layer thickness regulating member and the developing sleeve 31. It is made wider than the layer thickness regulation width, and specifically, it is set to around 3 to 5 mm.

  The reason for this setting is to secure a further supply amount of the developer in consideration that the developer carrying amount on the surface of the developing sleeve 31 is determined by the layer thickness regulation of the doctor sleeve 34. As a result, the layer thickness of the developer carried on the developing sleeve 31 in the doctor blade 34 can be secured.

  When the width dimension described above is extremely increased, the amount of the developer discharged is increased, the amount of developer blocked by the doctor blade 34 is increased, and this causes the condensation of the developer and the occurrence of pressure unevenness, Since it causes supply unevenness, it is desirable to have the width dimension described above.

As a fourth setting condition, the normal direction magnetic flux density from the developing sleeve 31 is set to be positive at the position of the slit 100.
That is, FIG. 7 shows this state, and the normal direction magnetic flux density from the developing sleeve 31 with respect to the slit 100 is positive, that is, the so-called magnetic field line S protrudes from one magnetic pole and changes to a magnetic pole having a polarity opposite to the one magnetic pole. The slit 100 is located at a protruding portion when returning.

  This is a condition for preventing the developer discharged from the slit 100 from being blocked by the magnetic field lines and falling to the developer recovery screw 33 side. As a result, all the developer supplied from the slit 100 is poured onto the peripheral surface of the developing sleeve 31 and conveyed to the developing area of the developing sleeve 31, and once used for development, the developer is discharged from the developing area. Will come to be. As a result, the amount of developer supplied to the developing sleeve 31 is depleted due to the inadvertent dropping of the developer toward the developer collecting screw 33 on the downstream side of the developer moving direction with respect to the developing sleeve 31. This is so as not to invite a situation that is insufficient.

In addition, since the upstream and downstream supply states in the developer moving direction can be directly supplied to the developing sleeve 31, it is possible to suppress the deterioration of the developer and supply it to the developing sleeve 31. It becomes.
In addition, it is preferable that the slit 100 is always present at a position lower than the developer surface in order to favorably discharge using gravity.

Next, a modified example of the above configuration will be described.
The slit 100 is not limited to a single one in the above-described configuration, and a plurality of slits 100 can be provided along the moving direction of the developer conveying screw 32.

FIG. 8 is a schematic diagram showing the configuration in this case. As shown in FIGS. 8A and 8B, a plurality of slits 100 and 100 ′ are provided along the circumferential direction of the developer conveying screw 31. Yes.
As the installation positions of these slits 100 and 100 ′, one 100 is set on a straight line connecting the axes of the developer conveying screw 32 and the developing sleeve 31 as in the above-described embodiment, and the other one 100 ′. Is set above the slit 100.

  In such a configuration, the developer discharge position is a position on a different peripheral surface of the developer conveying screw 32, and a state in which the supplied developer is poured toward the peripheral surface of the developing sleeve 32 is obtained. A stable supply amount can be supplied to the peripheral surface of the developing sleeve 31. Moreover, even if one slit is clogged due to the aggregation of the developer or the mixing of foreign matter, the supply from one slit can be performed, so that the supply can be prevented from becoming unstable.

  FIG. 8C is a modified example of the configuration shown in FIG. 8A, and the configuration shown in FIG. 8B is on a straight line connecting the axial centers of the developer conveying screw 32 and the developing sleeve 31. A slit (indicated by reference numeral 101 for the sake of convenience) different from the slit 100 positioned is positioned above the slit 100 and positioned higher than the peripheral surface of the developer conveying screw 32.

  In this case, the slit 101 has a function of returning the developer toward the developer conveying screw 32 without discharging the developer to the developing sleeve 31.

  In this configuration, although not shown, the excess developer regulated by the doctor blade facing the developing sleeve 31 moves between the walls in the developing tank toward the position of the slit 101 without staying at the position of the doctor blade. can do.

  Accordingly, since the developer applied to the doctor blade does not stay and condense in the portion after the layer pressure is regulated, the rotational load of the developing sleeve 31 is caused by friction caused by the condensed developer. The increase can be prevented. In addition, the developer moved from the position of the doctor blade is discharged from the slit 101, poured down toward the developer conveying screw, and again used for agitating and conveying, so that the above-described development due to the retention of the developer is also performed. An increase in driving load on the sleeve side can be prevented.

Next, the function when the airflow conveyance of the developer used in the developing device in the present embodiment is targeted will be described.
FIG. 9 is a diagram for explaining a comparison between the developing device according to the present embodiment and a conventionally used developing device.
FIG. 9B shows a configuration corresponding to the prior art. In FIG. 9B, when the inlet of the airflow conveyance unit 42 is connected to the developing tank, it overflows from the developing tank due to the introduction of air. The developer is easily ejected from the facing gap between the doctor blade communicating with the outside and the developing sleeve 32 as the airflow moves. In particular, when high-speed operation is performed, the amount of developer and the amount of air that circulate also increase, and scattering due to the ejection of the developer becomes significant.

  On the other hand, the configuration of the present embodiment shown in FIG. 9A does not have a function of supplying the developer in an overflow state depending on the installation position condition of the slit 100. For this reason, the developer and air introduced into the developing tank do not move directly to the developing sleeve 31 side, and the ejection in the above-described facing gap is suppressed. In particular, it is possible to easily prevent the developer from being ejected by making it difficult for air to escape by the slit 100 having a smaller area than the wall opening area provided to overflow the developing tank wall.

  In this configuration, in order to suppress an increase in internal pressure in the developer tank, an air vent 200 is provided in the upper vicinity in the vicinity of the developer transport screw serving as the developer supply position, and the air vent 200 is vented by an air vent such as a filter. The member which can do is arrange | positioned.

Next, a modified example related to the developing tank used in the developing device will be described.
FIG. 10 is a schematic diagram showing the configuration of the developing tank in the present embodiment.
In FIG. 10, the wall surface of the developing tank wall that can face the developer conveying screw 32 has a shape that follows the outer periphery of the developer conveying screw, and the distance from the outer peripheral surface of the developer conveying screw 32 is 0. It is set to about 5 to 1.5 mm.

  In such a configuration, even when the developer moves while spreading in the outer diameter direction of the developer conveying screw 32, the developer conveying amount can be increased toward the downstream side in the developer moving direction. Thereby, the moving amount of the developer can be increased with respect to the number of rotations of the developer conveying screw 32, thereby improving the conveying efficiency.

DESCRIPTION OF SYMBOLS 1 Photoconductor 3 Developing apparatus 6 Image forming part 30 Developing tank 30A Wall part 31 Developing sleeve 32 Developer conveyance screw 33 Developer collection screw 100 Slit 1000 Image forming apparatus

JP 2002-251070 A JP-A-11-167261 Patent No. 3795667

Claims (9)

A developer carrying member capable of carrying on the surface a developer for visual image processing of an electrostatic latent image on the latent image carrying member, and located in the vicinity of the upper portion of the developer carrying member, and developed in the longitudinal direction by rotation. A developer conveying member for supplying the developer to the developer carrying member while conveying the developer, a developer collecting member for collecting the developer after development, and between the developer conveying member and the developer carrying member. in the developing device provided with a current image tank capable of accommodating a developer therein has a wall portion,
The wall portion in the developing tank is formed with an opening that communicates the inside of the developing tank and the developer carrier, and the developer is discharged by gravity through the opening .
The developing device is characterized in that the opening is positioned on a straight line when axes of the developer conveying member, the developer carrying member, and the developer collecting member are located on a straight line .   The developing device according to claim 1, wherein the opening is positioned below a developer surface in which the developer conveying member is buried.   3. The developing device according to claim 1, wherein the opening is positioned above a straight line connecting axes of the developer conveying member and the developer carrying member. A developer carrying member capable of carrying on the surface a developer for visual image processing of an electrostatic latent image on the latent image carrying member, and located in the vicinity of the upper portion of the developer carrying member, and developed in the longitudinal direction by rotation. A developer conveying member for supplying the developer to the developer carrying member while conveying the developer, a developer collecting member for collecting the developer after development, and between the developer conveying member and the developer carrying member. In a developing device having a wall and a developing tank capable of accommodating a developer therein,
The wall portion in the developing tank is formed with an opening that communicates the inside of the developing tank and the developer carrier, and the developer is discharged by gravity through the opening.
The developing device according to claim 1, wherein a plurality of the openings are arranged along a rotation direction of the developer conveying member . A developer carrying member capable of carrying on the surface a developer for visual image processing of an electrostatic latent image on the latent image carrying member, and located in the vicinity of the upper portion of the developer carrying member, and developed in the longitudinal direction by rotation. A developer conveying member for supplying the developer to the developer carrying member while conveying the developer, a developer collecting member for collecting the developer after development, and between the developer conveying member and the developer carrying member. In a developing device having a wall and a developing tank capable of accommodating a developer therein,
The wall portion in the developing tank is formed with an opening that communicates the inside of the developing tank and the developer carrier, and the developer is discharged by gravity through the opening.
2. A developing apparatus according to claim 1, wherein a carrier air flow inlet for introducing a developer carrier air flow is connected in the vicinity of the developer supply position, and an air vent is provided in the vicinity of the developer supply position . The width of the opening is made wider than a layer thickness set by a developing layer thickness regulating member provided in the developing tank. Development device. The developing device according to claim 5 , wherein the air vent is provided at a position higher than an installation position of the developer conveying member . A wall surface facing the developer transport member in the developer tank wall portion is shaped to follow the outer shape of the developer transport member, and a gap between the developer transport member and the developer transport member is set to 1.5 mm. an apparatus according to any one of claims 1 to 7, characterized in that. An image forming apparatus using the developing device according to claim 1 .

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