JP4731959B2 - Development device - Google Patents

Description

  The present invention relates to an electrostatic latent image formed on an image carrier (photoreceptor) of an image forming apparatus using a two-component developer of an electrophotographic system used in a copying machine, a printer, a facsimile, etc., as a toner image. The present invention relates to a developing device that visualizes.

  2. Description of the Related Art A developing device for an image forming apparatus such as a copying machine or a printer that uses electrophotography often uses a two-component developer composed of toner and a carrier. In an image forming apparatus using a two-component developer, only toner is consumed when a toner image is formed. Therefore, in order to continue to form a good image, it is necessary to replenish new toner as much as the consumed toner, and always keep the toner concentration of the developer contained in the developing device at an appropriate level. The replenished toner is agitated and mixed with the developer by the conveying and mixing member. However, if the agitating and mixing is insufficient at this time, the replenished toner is not sufficiently charged and a slight opening such as under the developing sleeve is formed. The toner tends to cause the toner to flow out of the developing device to the outside of the developing device, so-called toner scattering. When such toner scattering occurs, the inside of the image forming apparatus is contaminated with toner. If the degree is poor, the scattered toner may adhere to the photosensitive member and stain the image. In addition, a toner having a low charge amount also causes a problem of background stains adhering to the background portion (white portion) of an image. In addition, if the replenishment toner is not sufficiently mixed and stirred with the developer and is developed in the form of an aggregate, there is a problem that a defect occurs in the toner image.

  For the purpose of preventing toner scattering and image defects due to such insufficient mixing and stirring, a device in which a large number of stirring blades and the like are provided on the conveying and mixing member in the developing device to improve mixing and stirring has been proposed and used. . This solved the initial problem, but on the other hand, the agitation stress was increased, the charging ability due to the deterioration of the developer over time was reduced, and as a result, the charge amount was not stable, such as toner scattering over time and background contamination. Problems remain (If developer is stressed, charging capacity decreases due to carrier coat scraping, charging capacity decreases due to toner embedding, and fluidity decreases. Fluidity decreases due to decreased transfer rate. Also cause). Therefore, it is necessary to devise a method for charging the developer efficiently without giving as much stress as possible.

  In Patent Document 1, by providing an agitation assisting member that is inclined in the direction of accelerating the flow of the developer on the screw having a spiral structure, the agitation and mixing performance of the developer and the replenishment toner is improved, and the stress applied to the developer is reduced. A method has been proposed.

  Patent Document 2 proposes a configuration in which, in addition to a conventional developer stirring and conveying unit, a developer containing unit used for forming a toner image and having a reduced toner density is provided, and toner is supplied thereto.

  Moreover, in patent document 3, the inside of the developer supply roller which has a blade | wing on an outer periphery is made into a tubular shape, several opening is provided, and the spiral member is incorporated.

  In Patent Document 4, a hollow portion is formed in an agitation roller that supplies developer to the developing roller, and a screw that agitates and conveys toner in the reverse direction is provided therein to improve toner dispersibility and reduce the size. .

  In Patent Document 5, a hollow portion is formed in a stirring rotor for supplying a developer to a developing sleeve, a plurality of nozzles are provided on a hollow portion tube wall, and toner is supplied from a replenishing portion, thereby dispersing toner. And uniformity of density.

Japanese Patent Laid-Open No. 5-19621 JP 2002-182463 A Japanese Utility Model Publication No. 58-126465 Japanese Patent Laid-Open No. 2-73659 JP-A-4-81162

  However, in the technology disclosed in Patent Document 1, stress and mixed stirring performance that the addition stirring of the auxiliary member itself improves the stress and the mixed stirring performance is lowered when the auxiliary member is obliquely attached to reduce the stress. The trade-off relationship problem occurs.

  Further, in the configuration of Patent Document 2, since a low toner concentration developer accommodating portion is newly provided for the developer agitating and conveying portion, the apparatus is increased in size. Further, since the developer agitating and conveying section is further provided with a mixing and agitating region for the low toner concentration developer and the replenishing toner, the stress on the developer may increase as a whole.

  In Patent Document 3, since toner is replenished to an external developer, the toner does not necessarily enter the developer supply roller, so mixing and stirring properties are not sufficient. Furthermore, since the interchange between the internal developer and the external developer is not constant, the developer concentration uniformity is not sufficient.

  In Patent Document 4, only one twin screw type screw is provided inside the other screw, and the toner is supplied to the upper part of the developer. The problem of insufficient charge amount remains.

  Further, in Patent Document 5, the replenished toner is supplied to the developing sleeve without sufficient stirring time, and the problem of insufficient charge amount remains. In addition, the toner is clogged in the nozzles, causing variations in the replenishment amount and poor replenishment. As a result, the effects of toner dispersibility and density uniformity cannot be sufficiently obtained.

  The present invention has been made by paying attention to the above circumstances, and its purpose is to improve the mixing and stirring performance of the replenishment toner and the developer without applying excessive stress to the developer, and to prevent charging failure. An object of the present invention is to provide a developing device that can eliminate toner density variation, prevent toner scattering and image defects, and obtain a stable image over a long period of time.

In order to solve the above problems, the invention described in claim 1 is a developing device using a two-component developer composed of toner and a carrier, and is a first device for circulating and conveying the developer in the developing device. A first developer transport member and a second developer transport member, the first developer transport member and the second developer transport member having mutually opposite rotation axes and having a transport direction opposite to each other, and a first developer a developer carrying member and the rotation axis is provided in the vicinity is provided in parallel with the first developer conveying member for carrying a developer conveying member for conveying, it is provided in the second developer conveying member, a new in the developing device and a toner supply path only the toner is moved to be supplied to, provided inside the second developer conveying member, the length of the second current image-transporting member from the developer carrying direction most upstream side a plurality of toner discharge hole provided in a shorter range than is And conveying means for discharging the toner in the toner supply path to the second developer conveying member out through the toner discharge hole, for opening and closing the toner discharging hole, provided in the second developer conveying member A discharge hole lid that opens the toner discharge hole by its own weight when the second developer transport member occupies a downward direction of gravity during rotation of the second developer conveying member .

According to a second aspect of the present invention, in the first aspect of the present invention, the toner conveying means includes a helical member provided in a toner supply path inside the second developer conveying member, and a helical shape. Drive means for rotationally driving the member.

According to a third aspect of the present invention, in the second aspect of the present invention, the second developer conveying member is driven to rotate, and the rotational direction of the helical member is set to the rotational direction of the second developer conveying member. It is characterized by the reverse direction.

Further, The invention described in claim 4, in the invention described in any one of claims 1 to 3, a part or whole of said conveying means abuts to the toner discharge hole As described above, a brush is provided.

Further, the invention described in claim 5 is the invention described in claim 1, wherein said conveying means is a spiral brush.

Further, the invention described in claim 6, in the invention described in claim 1, wherein the conveying means includes characterized in that it comprises a helical member which is fixed to the inner wall of the toner supply path To do.

According to a seventh aspect of the present invention, there is provided the air supply according to any one of the first to fourth aspects, wherein the toner conveying means supplies air to the newly supplied toner. It is a means.

Further, The invention described in claim 8, in the invention described in claim 1 or claim 7, wherein the conveying means is pneumatically toner and newly replenished provided inside the second developer conveying member It is a uniaxial eccentric screw pump conveyed using.
The invention described in claim 9 is the invention described in any one of claims 1 to 8, wherein at least the area of the toner discharge hole at the most downstream side is larger than that of the other toner discharge holes. It is large.

  The invention described in claim 10 is characterized in that, in the invention described in claim 7, the supply of air is performed at regular intervals or at all times other than during toner replenishment.

According to the developing device of the present invention, without excessive stress applied to the developer, the mixing and stirring performance of the replenishment toner and the developer is improved to eliminate charging failure and toner density variation, thereby preventing toner scattering and image defects. A stable image can be obtained over a long period of time. When the discharge hole lid of the toner discharge hole comes downward in the gravity, the toner discharge hole is opened by its own weight, and the toner is transported in the toner replenishment path by the toner conveying means. When transported, only the downward toner is discharged. Therefore, the toner is supplied only in the downward direction in the developer, the toner is more easily taken into the developer, and the dispersibility is improved .

  An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show a developing device according to an embodiment of the present invention. The developing device is used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a printing machine.

  In the figure, reference numeral 1 denotes a photoconductor, and an electrostatic latent image is formed on the surface of the photoconductor 1 by a charging device and an optical writing device (not shown). The developing device 2 develops the electrostatic latent image formed on the photosensitive member 1 with toner to form a visible image. The image forming apparatus includes a charging device, a writing device, a transfer device (not shown), a cleaning device, and a fixing device for fixing an image after transfer.

  Reference numeral 12 denotes a casing constituting the developing device 2, and conveying screws 9 and 10 having spiral fins therein are rotated in the directions of arrows B and C. In this portion, development in which toner and carrier are mixed is developed. Contains the medicine. On the right side of the partition plate 13 in the figure, the developer is conveyed from the back side to the near side in the figure, and on the left side, the developer is conveyed from the near side to the back side. A portion without the central partition plate 13 is provided on the back side and the near side, and the developer is mixed and stirred while circulating.

  The developing roller 11 as a developer carrying member includes a developing sleeve 16 in which a nonmagnetic material is formed in a cylindrical shape and a magnet roller in which a plurality of magnetic poles are magnetized, and a magnet roller is disposed inside the developing sleeve 16. Yes. The developer mixed and stirred while being circulated is magnetically attracted by the magnetic force of the magnet in the developing roller, and is provided on the surface of the developing sleeve 16 (not shown) as the developing sleeve 16 rotates in the direction of arrow A. It is conveyed by unevenness. The conveyed developer is made uniform by the doctor blade 14 and developed on the photoreceptor 1.

  Here, only the toner adheres to the photosensitive member 1, and the toner that has not been developed and the carrier that has transported the toner are carried again to the agitating and conveying unit in the developing device 2 as the developing sleeve 16 rotates. Released. In order to keep the amount of toner in the developer circulating in the developing device 2 constant, the amount of toner used for development is replenished from a toner replenishing device described later.

  Reference numeral 8 denotes a toner concentration sensor, which is a sensor that detects the toner concentration in the developer by measuring the magnetic permeability of the developer in the developing device 2. Due to the fluctuation of the detection output, the toner is replenished so as to keep the toner concentration in the developer in the developing device 2 constant. However, since the magnetic permeability of the two-component developer fluctuates due to changes in the environment, changes in the bulk density of the developer, and the like, the output target value of the toner concentration sensor 8 is corrected as appropriate. Specifically, the image density of the reference toner image formed on the photoreceptor 1 is measured using the image density sensor 15, and the output target value of the toner density sensor 15 is set according to the output result of the image density sensor 15. to correct.

  The toner developed on the photoreceptor 1 is transferred and fixed on the upper surface of the conveyed paper by a transfer device and a fixing device (not shown), and the paper is stocked on a paper discharge tray (not shown). Further, the residual toner on the surface of the photoreceptor after the image transfer is removed by a cleaning device.

  FIG. 2 shows an embodiment of the toner replenishing unit. Only in the toner replenishment side portion of the transport screw (first developer transport member) 20 for transporting the developer 90 is a toner replenishment path 22 as a transport path inside the shaft, and the toner replenishment path 22 has a spiral auger (spiral). A toner discharge hole 23 is provided in a portion of the conveying screw shaft (second developer conveying member) 21 where the toner supply path 22 is located. During image formation, that is, when the developing device 2 is driven, the conveying screw 20 rotates to circulate and convey the developer 90. Only when a toner replenishment signal is input from the toner density sensor, the auger 24 is driven via the driving means 80 to convey the toner in the toner replenishment path 22 in the left direction in the figure.

  The conveyed toner is discharged out of the shaft from the toner discharge hole 23 and taken into the developer 90, and is conveyed leftward together with the developer 90 by the conveying screw 20. Since the toner discharge hole 23 supplies the toner into the developer 90 while the conveying screw 20 rotates, the toner exists in the developer 90 in a very high dispersion state when the toner is supplied. As a result, the start-up of charging of the toner becomes very fast, and as a result, the charge amount is stabilized. Therefore, it is possible to reduce the stress of the other part of the developing device 2, for example, the doctor blade 14 which is said to be necessary for the start-up of charging.

The discharge hole 23 is larger than the shape of the toner (the particle diameter of the toner is generally about 1 to 20 μm) and is about 0.02 to 5 mm, and the shape may be round or square. The toner is optimized as appropriate in consideration of the fluidity of the toner (ease of clogging in the discharge holes) and the dispersibility in the developer 90.
The conveying screw 20 is preferably about φ10 to φ30, the shaft is about φ5 to φ20, the replenishment path is about φ4 to φ18, and the auger has an outer diameter of about φ3 to φ17. That's fine.

  The toner cartridge 25 is connected to a fixed toner replenishing shaft 26 in the figure, and the toner in the toner cartridge sequentially drops into the toner replenishing shaft 26 due to gravity. In order to improve the layout of the entire image forming apparatus and the reliability of toner discharge from the toner cartridge 25, the toner cartridge 25 is arranged away from the toner replenishing shaft 26, and the toner cartridge using a conventionally known conveying means such as a screw. Needless to say, the toner can be transported from 25 to the toner supply shaft 26.

  Further, although there is a concern about the toner clogging in the discharge hole 23, the developer 90 occasionally enters the toner supply path 22 from the discharge hole 23 due to the rotation of the conveying screw 20, so that the toner clogging hardly occurs. ing.

  Further, by driving the conveying screw 20 and the auger 24 so that they are in the opposite rotation directions, the rotational speed of the auger 24 is increased relative to the toner replenishment path 22 so that the toner can be efficiently conveyed. (If the rotation direction of the conveying screw 20 and the auger 24 is the same, the relative rotation speed of the auger decreases, so the toner conveyance amount is lower than when the conveying screw 20 is fixed and the auger 24 is rotated. Resulting in). Thereby, the rotation speed of the auger 24 can be reduced, and the drive unit can be reduced in size and the power consumption can be reduced.

  FIG. 3 shows another embodiment of the developing device of the present invention. Hereinafter, the same name is used for the same component as FIG. As in FIG. 2, a toner replenishment path 22 is provided inside the toner replenishment side of the conveying screw 20, but a spiral convex portion 30 is integrally formed on the outer wall of the toner replenishment path 22 (may be a separate body). The toner in the toner supply path 22 is guided to the spiral convex portion 30 and conveyed leftward by the rotation of the conveying screw 20. Thereafter, the action of discharging from the toner discharge hole 23 into the developer 90 is almost the same as the example of FIG. In this configuration, since the conveying member and the driving means are not newly provided inside the conveying screw 20, the cost is reduced and the size is reduced as compared with the example of FIG. However, since the toner is transported and discharged when the transport screw 20 is driven, it is necessary to regulate (control) the amount of toner supplied to the toner replenishment path by the toner discharge valve 32 and the like in the figure. In contrast, the example of FIG. 2 is advantageous in that the toner conveyance amount can be easily adjusted by the auger 24.

  FIG. 4 shows another embodiment of the developing device of the present invention. The toner dropped from the toner cartridge 25 is transported to the left in the toner supply path 22 by supplying air from an air pump (air supply means) 40 and discharged into the developer 90 from the toner discharge hole 23. Since a lot of air is contained in the toner and the fluidity is high, the toner 90 is further dispersed in the developer 90. The flow rate of the air supplied to the toner is preferably 5 to 70 cc with respect to 1 g of toner and the pressure is about 5 to 50 kPa from the viewpoint of improving the dispersibility of the toner in the developer 90, but is optimized depending on the fluidity of the toner used. It is desirable.

  Further, since the toner flow is good, the toner discharge hole 23 is not easily clogged, and even if the toner discharge hole 23 is clogged, the clogging can be eliminated by the air pressure, so that the reliability is improved. Furthermore, by providing the toner discharge valve 32 as shown in FIG. 5 in the toner cartridge 25, it is possible to send only air from the discharge hole 23, and the discharge hole 23 can be more effectively cleaned.

  FIG. 5 shows another embodiment of the developing device of the present invention. A screw pump 50 is provided in the conveying screw shaft 21. The screw pump 50 includes a rigid single-screw-shaped rotor 51 and a stator 52 formed of an elastic body in which a double-screw through-hole is formed. The stator 52 is fixed to the conveying screw shaft 21, and the rotor 51 is set in the through hole. The rotor 51 is connected to the rotor shaft 60, and the rotor shaft 60 is fixed to the outside. When the conveying screw 20 rotates, the stator 52 fixed to the conveying screw 20 rotates together to generate suction pressure upstream of the screw pump 50, sucks toner in this portion, passes through the space inside the rotor 51 and the stator 52. The toner is discharged to the discharge portion (left space) of the screw pump 50 and the toner is discharged from the discharge hole into the developer 90.

  A rigid material such as rotor metal or resin is used, and the stator 52 uses an elastic body such as rubber or resin. When the rotor 51 is set on the stator 52, the rotor 51 bites into and comes into contact with the stator 52 and is closed. Some spaces are formed. By rotating the sealed space, a negative pressure can be generated on the upstream side and a positive pressure on the downstream side. Further, the sealed space is sequentially filled with toner, and a movement amount (discharge amount) corresponding to the rotation amount of the rotor (stator) 51 can be obtained with high accuracy.

  The toner replenishing shaft 26 is fixed and guides the toner dropped from the toner cartridge 25 through the toner discharge valve 32 into the conveying screw shaft 21, and at the same time the toner passage in this portion is sealed so that the toner does not leak to the outside. Also has a seal function.

  FIG. 6 is another embodiment of the developing device of the present invention, and is an enlarged view of the inside of the toner supply path 22 of the conveying screw 20 and the toner discharge hole 23 portion. The toner discharge hole 23 is provided with a discharge hole lid 70. When the toner discharge hole 23 comes in the downward direction of gravity, the lid 70 opens to the discharge hole 23 by its own weight as shown in the figure. Therefore, when the toner is conveyed leftward in the replenishment path 22 by the toner conveying means, the toner is not discharged from the discharge hole 23 at the upper part (and not shown) by the discharge hole lid 70. Only the downward toner is discharged. Therefore, the toner is supplied only in the downward direction in the developer 90, the toner is more easily taken into the developer 90, and the dispersibility is improved.

  Since the developer 90 in the developing device is a powder, during conveyance by the conveyance screw 20, the powder surface instantaneously undulates as shown in the figure, and the conveyance screw shaft surface may or may not be exposed. There may be a case where the developer 90 above the shaft is small. In this case, the toner is preferentially discharged from the upper discharge hole where the resistance by the developer 90 is small, and as a result, a large amount of toner is supplied to the upper surface of the developer 90. In this case, the effect of dispersing the toner in the developer 90 is greatly impaired. Therefore, the use of this example ensures improvement in dispersibility. Further, this example is particularly effective when combined with the case of using the conveying means using the pressure shown in FIGS. This is because even if the screw shaft is not exposed (even if there is sufficient developer 90 at the upper part of the shaft), the toner that has come out vigorously due to the pressure from the upper discharge hole breaks through the developer 90 and comes out to the upper surface. It is because there is a case where it ends up.

  FIG. 7 shows another embodiment of the toner conveying means. The toner conveying means is obtained by attaching a bristle brush 75 to a part of the auger 24 similar to FIG. The bristle brush 75 is also rotationally driven by the rotational driving of the toner conveying means in accordance with the toner replenishment signal, and cleaning can be performed when the discharge hole 23 is passed to remove clogging. Therefore, a stable toner replenishment amount can be secured even over time. Further, when the bristle brush 75 rotates, the toner is dispersed in the form of a mist to further improve the dispersibility in the developer 90 and the charge start-up property.

  FIG. 8 shows another embodiment of the toner conveying means. The toner conveying means is a spiral wound around a bristle brush 75 (spiral brush), which is the same as the effect of FIG. 7, but is further simplified to ensure miniaturization, low cost and reliability. It is a thing.

  FIG. 9 shows another embodiment of the discharge hole of the conveying screw 20. The discharge hole 23 is a round hole, and the discharge hole 23 on the most downstream side in the toner conveyance direction is the largest. If the diameters of the four discharge holes 23 from the most upstream are a, the diameter is 4 × a. Furthermore, the discharge hole at the most downstream one has a diameter of about 2a.

  In some cases, the amount of toner discharged from the discharge hole 23 is smaller than the amount of toner conveyed in the toner replenishment path 22. In this case, the toner is pressed and solidified in the toner replenishment path 22, causing a problem of toner replenishment failure. However, since the toner is reliably discharged from the most downstream toner discharge hole 23 by adopting the configuration of the discharge hole of this example, the above problem can be prevented.

  In this example, the toner is supplied into the developer 90, but it is needless to say that the toner can be used to supply a premix agent in which a carrier is mixed in the toner.

  The premix agent is a developer having a higher toner concentration than the developer 90 used in the developing device 2. The developer used in the developing device 2 is about 80 to 98% by weight ratio of the carrier to the toner, but about 1% to 30% by weight ratio of the carrier to the toner.

  As described above, in the above embodiment, the toner conveying means (24) for discharging the toner in the toner replenishing path 22 (conveying path) to the outside of the developer conveying member (conveying screw shaft 21) through the discharge hole 23. , 90) are provided in the transport path 22. Therefore, the toner can be efficiently dispersed in the developer without replenishing the toner in the developer without causing the toner to slide on the developer and without increasing the stress on the replenished toner or the developer. In addition, the carrier can flow back from the discharge hole 23 appropriately, and supply failure due to clogging of the discharge hole 23 and supply amount variation can be prevented. Further, since contamination in the image forming apparatus due to toner scattering or the like can be prevented, the maintenance time and frequency of service personnel can be reduced. In addition, since contamination in the image forming apparatus due to toner scattering or the like can be prevented, machine downtime associated with maintenance can be reduced. Further, the amount of toner to be replenished at a time can be increased, and a very small amount of toner replenishment control is not required, the control is simplified, the cost of the apparatus is reduced, and the reliability of the toner replenishing apparatus is improved.

  In the above-described embodiment, the toner conveying means includes an auger 24 provided in a toner conveying path (toner supply path 22) inside the conveying screw shaft 21 serving as a second developer conveying member, and a drive for rotating the auger 24. Means 80. Therefore, the auger 23 reliably supplies toner into the developer with a relatively simple configuration.

  In the above embodiment, the second developer conveying member (conveying screw shaft 21) is driven to rotate, and the rotation direction of the auger 23 is changed to the conveying member (conveying screw 20 as the first developer conveying member (therefore, the second developer conveying member). The direction of rotation of the conveying screw shaft 21)) as the developer conveying member is opposite. By reversing the direction of rotation in this way, the number of rotations of the conveying member is relatively increased, and toner is efficiently conveyed. Further, the toner is well agitated by the relative rotation speed UP and the rotation of the peripheral wall, the fluidity is improved, and the toner is easily dispersed in the developer, and at the same time, the discharge hole 23 can be prevented from being clogged.

  In the above embodiment, the brush 75 is provided on a part or the whole of the toner conveying means so as to contact the discharge hole 23. Therefore, the brush 75 can reliably prevent the discharge hole 23 from being clogged.

  In the above embodiment, the toner conveying means is the spiral brush 75. Therefore, the above effect can be obtained with one member, and the cost and size of the apparatus can be reduced.

  In the above-described embodiment, the toner conveying unit includes the spiral member (auger) 24 fixed to the inner wall of the toner conveying path inside the conveying member, and the driving unit 80 that rotationally drives the conveying member. Therefore, cost reduction and size reduction can be achieved without the need to provide the conveying member and its driving means alone.

  In the above-described embodiment, the toner conveying unit is the air supply unit (air pump) 40 that supplies air into the newly supplied developer. Therefore, since the toner and developer are fluidized by air, the dispersibility is further improved, and at the same time, the discharge holes 23 can be blocked and the replenishment toner can be prevented from aggregating. Further, the output value of the toner density sensor due to the change in the fluidity (bulk density) of the developer can be quickly stabilized. In addition, the developer fluidity increases, so that the developer can move easily when stress is applied to the developer. As a result, the developer is less susceptible to stress (released), and the toner additive is buried and the carrier film is scraped. The developer deterioration that occurs can be suppressed.

  In the above-described embodiment, the toner conveying means is the uniaxial eccentric screw pump 50 that is provided inside the conveying member and conveys the newly replenished developer using air pressure. Therefore, highly accurate toner replenishment control can be performed by the screw pump 50, and at the same time, a valve function for preventing excessive backflow of the carrier can be used.

  In the above embodiment, at least the area of the most downstream discharge hole 23 is larger than that of the other discharge holes 23. Therefore, the toner clogging in the transport path 22 can be reliably prevented.

  In the above-described embodiment, air is supplied at regular intervals or at all times even when toner is not supplied. For this reason, if air is supplied in advance into the developer, the gaps between the developers increase, and the replenished toner is better dispersed in the developer. In addition, since dispersibility is increased and charging is stabilized, image quality is stabilized and defective image quality such as background stains can be prevented. Further, the dispersibility is improved, and the toner scattering due to the top slip of the replenishing toner can be prevented. Further, by supplying air without attaching new parts, it is possible to prevent clogging of the toner discharge hole 23 due to the inflow of the developer into the toner supply port and the inflow of the developer.

1 is a schematic view of a developing device according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view illustrating a first embodiment of a toner supply unit. FIG. 6 is a schematic cross-sectional view illustrating a second embodiment of a toner replenishing unit. FIG. 6 is a schematic cross-sectional view illustrating a third embodiment of a toner replenishing unit. FIG. 10 is a schematic cross-sectional view illustrating a fourth embodiment of a toner replenishing portion. FIG. 10 is a schematic cross-sectional view illustrating a fifth embodiment of a toner replenishing portion. FIG. 10 is a schematic cross-sectional view illustrating a modified example of the toner conveying unit. FIG. 10 is a schematic cross-sectional view showing another modified example of the toner conveying unit. It is a schematic sectional drawing which shows other embodiment of a conveyance screw.

Explanation of symbols

11 Development roller (developer carrier)
20 Conveying screw (first developer conveying member)
21 Conveying screw shaft (second developer conveying member)
22 Toner supply path (conveyance path)
23 toner discharge hole 24 auger (spiral member, toner conveying means)
25 Toner cartridge 32 Toner discharge valve 40 Air pump (air supply means)
50 Screw pump 75 Brush 80 Driving means (toner conveying means)

Claims (10)

A developing device using a two-component developer comprising a toner and a carrier,
A first developer transport member and a second developer transport member for circulating and transporting the developer in the developing device, the rotation axes of which are parallel to each other and the transport direction is opposite. A member and a second developer conveying member;
A developer carrying member provided in the vicinity of the first developer carrying member for carrying the developer carried by the first developer carrying member and having a rotation axis provided in parallel;
A toner replenishment path that is provided inside the second developer conveying member and in which only newly replenished toner moves ;
In a developing device comprising:
Provided in the second developer conveying member, a plurality of toner discharge hole provided from the developer carrying direction most upstream side in a shorter range than the length of the second developer conveying member,
And conveying means for discharging the toner in the toner supply path to the second developer conveying member out through the toner discharge hole,
A discharge hole lid provided on the second developer conveying member for opening and closing the toner discharge hole, and when the second developer conveying member occupies a downward direction of gravity, the toner discharge hole is caused by its own weight. Open the drain hole lid,
Developing apparatus is characterized in that it comprises. 2. The toner conveying means includes a spiral member provided in a toner replenishment path inside a second developer conveying member, and a driving unit that rotationally drives the spiral member. Development device. The developing device according to claim 2, wherein the second developer conveying member is driven to rotate, and the rotation direction of the spiral member is set to be opposite to the rotation direction of the second developer conveying member. 4. The developing device according to claim 1, wherein a brush is provided on a part or the whole of the toner conveying unit so as to abut on the toner discharge hole. 5. The developing device according to claim 1, wherein the toner conveying unit is a spiral brush. Said conveying means includes a developing device according to claim 1, characterized in that it comprises a helical member which is fixed to the inner wall of the toner supply passage. 5. The developing device according to claim 1, wherein the toner conveying unit is an air supply unit that supplies air into newly supplied toner . 6. 8. The uniaxial eccentric screw pump according to claim 1, wherein the toner conveying means is a uniaxial eccentric screw pump that is provided inside the second developer conveying member and conveys newly supplied toner using air pressure. Development device. 9. The developing device according to claim 1, wherein an area of at least the most downstream toner discharge hole is larger than that of the other toner discharge holes.   The developing device according to claim 7, wherein the supply of air is performed at regular intervals or at all times even when toner is not replenished.

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