JP2010204399A - Developing device and image forming apparatus - Google Patents

Abstract

【Task】
Prevents backflow and overflow of the collected liquid developer, maintains high reliability in the developing device, and prevents internal contamination.
[Solution]
A developer carrier 36 that rotates while carrying the liquid developer, a cleaning unit 361 that contacts the developer carrier 36 and collects the liquid developer, and a collection that stores the liquid developer collected by the cleaning unit 361 A developer storage unit 312, a transport channel 33 connected to the recovered developer storage unit 312, and transport units having different transport amounts of liquid developer disposed in the recovered developer storage unit 312 and the transport channel 33. It has the conveyance member 32 which has.
[Selection] Figure 6

Description

  The present invention relates to a developing device for developing an electrostatic latent image formed on an image carrier with a liquid developer having a toner and a carrier liquid, and a developer image developed by the developing device is transferred to a recording material and fixed. The present invention relates to an image forming apparatus that forms an image.

Various image forming apparatuses for developing and visualizing an electrostatic latent image using a high-viscosity liquid developer in which a toner composed of a solid component is dispersed in a liquid solvent as a carrier liquid have been proposed. The developer used in this image forming apparatus has solid components (toner particles) suspended in a highly viscous organic solvent (carrier liquid) having electrical insulation properties such as silicon oil, mineral oil, and edible oil. Is. For the toner particles, extremely fine particles having a particle diameter of about 1 μm are used.
Compared with a conventional dry image forming apparatus using a particle diameter of 7 μm, high image quality can be achieved.

  In an image forming apparatus using such a liquid developer, first, the surface of a photoreceptor as an image carrier is uniformly charged. Next, the surface of the photoconductor is exposed by an exposure unit according to the input image data, and an electrostatic latent image is formed on the surface of the photoconductor. In order to develop the electrostatic latent image as a toner image, a developing device that applies a liquid developer onto the photoreceptor on which the electrostatic latent image is formed is used.

  Japanese Patent Application Laid-Open No. 2005-228561 discloses the following description regarding the supply and recovery of the liquid developer in such a developing device. The liquid developer supplied to each roller such as the developing roller 402 from the developer storage tank 401 is removed by the cleaning unit 411 after development and is stored in a temporary storage unit 412 provided adjacent to the developer storage tank 401. Collected. The liquid developer collected in the temporary storage unit 412 is sent to the density adjusting unit by the conveying screw 413, and after the developer concentration is adjusted in the density adjusting unit, the liquid developer is returned to the developer containing tank 401. Reused.

  On the other hand, the supply amount of the liquid developer into the developer storage tank 401 is set to be slightly larger than the consumption amount of the liquid developer. As a result, the liquid developer overflowing from the developer storage tank 401 is returned into the temporary storage unit 412. Thus, the liquid developer is always circulated.

JP 2003-98833 A

  In the developing device disclosed in Patent Document 1, the liquid developer is constantly circulated by overflowing from the developer storage tank 401 to the temporary storage unit 412, and the concentration in the developer storage tank 401 is maintained.

  When such a developing device is operated after being stopped for a long period of time, the developer that has been deposited on the cleaning unit 411 or the like falls with time, and an excessive amount of liquid developer is stored in the temporary storage unit 412. It becomes a deposited state. When the operation is started in this state, the transport capacity may be temporarily exceeded, and the liquid developer in the temporary storage unit 412 may flow backward to the developer storage tank 401 or overflow from the temporary storage unit 412.

  When the developer flows backward to the developer storage tank 401 side, problems such as disturbing the adjusted concentration of the liquid developer and clogging of the liquid developer containing solid matter by the anilox roller occur. Further, overflowing from the temporary storage unit 412 causes in-flight contamination.

  The present invention changes the discharge capacity of the transport member that transports the collected liquid developer depending on the site, and prevents backflow and overflow of the collected liquid developer without increasing the size of the apparatus, and is highly reliable. Maintenance and prevention of in-flight contamination can be achieved. Therefore, the developing device and the image forming apparatus of the present invention adopt the following configuration.

  The developing device of the present invention has a supply developer storage section for storing a liquid developer having toner and a carrier liquid, a developer carrier that carries and rotates the liquid developer, and a developer carrier that contacts the developer carrier. A cleaning unit that contacts and collects the liquid developer; a recovered developer storage unit that stores the liquid developer recovered by the cleaning unit; a transport channel connected to the recovered developer storage unit; And a transport member disposed in the collected developer storage section and the transport flow path and having transport sections having different transport amounts of the liquid developer.

  Furthermore, in the developing device of the present invention, the transport member is disposed in a first transport unit disposed in the transport channel, in the transport channel inlet of the recovered developer storage unit, and in the vicinity of the transport channel. A transport amount of the liquid developer of the second transport portion is smaller than a transport amount of the liquid developer of the first transport portion.

  Further, the developing device of the present invention is provided with a wall portion disposed between the recovered developer storage portion and the supply developer storage portion, and disposed on the wall portion, and stored in the supply developer storage portion. And a recovery port for allowing the liquid developer to flow into the recovered developer storage section.

  Further, the developing device of the present invention is configured such that the recovery port is disposed on the transport direction side of the transport member and the second recovery port is disposed on the opposite side of the transport direction of the transport member. It has a mouth.

  Furthermore, in the developing device of the present invention, the transport member includes a third transport unit disposed on the opposite side of the transport direction with respect to the second transport unit, and transports the liquid developer in the second transport unit. The amount is set to be smaller than the transport amount of the liquid developer of the third transport unit.

  Furthermore, in the developing device of the present invention, the transport member includes a fourth transport unit disposed on the opposite side of the transport direction with respect to the third transport unit, and transports the liquid developer in the fourth transport unit. The amount is set to be larger than the transport amount of the liquid developer of the third transport unit.

  Furthermore, in the developing device of the present invention, the first transport unit and the second transport unit have a screw shape in which at least one of lead angle, pitch, number of strips, material, and diameter is different.

The image forming apparatus according to the present invention also includes a supply developer storage unit that stores a liquid developer having toner and a carrier liquid, a developer carrier that rotates by supporting the liquid developer, and a developer carrier. A cleaning unit that abuts and collects the liquid developer, a collected developer storage unit that stores the liquid developer collected by the cleaning unit, a transport channel connected to the collected developer storage unit, and the collected development The image forming apparatus includes a developing unit having a transport member having transporting portions having different transport amounts disposed in the developer storage unit and the transport flow path, and an image bearing member developed by the developer bearing member.

1 is a cross-sectional view illustrating a main configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating main components of an image forming unit and a developing device according to an embodiment of the present invention. FIG. 5 is a diagram illustrating a state of liquid developer adhesion in the developing device according to the embodiment of the invention. FIG. 6 is a diagram illustrating a flow of the liquid developer in the developer container according to the embodiment of the invention. The figure which shows the mode of the liquid developer in the conventional developer collection part. FIG. 4 is a diagram illustrating a state of a liquid developer in a developer recovery unit according to an embodiment of the present invention. The figure which shows the various screw shapes which concern on embodiment of this invention. The figure which shows the characteristic value of the various screws which concern on embodiment of this invention. The figure which shows the conveyance amount with respect to the lead angle of a screw. The figure which showed the mode of the liquid developer in the developer collection part which concerns on other embodiment of this invention. The figure which showed the mode of the liquid developer in the developer collection part which concerns on other embodiment of this invention. The figure which showed the mode of the liquid developer in the developer collection part which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a main configuration of an image forming apparatus according to an embodiment of the present invention. The four developing devices 30Y, 30M, 30C, and 30K are disposed below the image forming unit with respect to the image forming unit disposed at the center of the image forming apparatus. Arranged above the image forming unit. Hereinafter, the image forming unit and the developing devices 30Y, 30M, 30C, and 30K will be described. However, since the configurations of the respective colors are the same, the alphabetical suffixes indicating the colors are omitted. The image forming apparatus according to the present embodiment is capable of forming a full-color image using four colors of YMCK. However, the image forming apparatus is not limited to this embodiment. For example, the image forming apparatus employs an appropriate number of colors such as single color and two colors. Also good.

  The image forming unit includes an image carrier 10, a corona charger 11, an exposure unit 12, and the like. The exposure unit 12 includes a light source such as an LED or a semiconductor laser, and irradiates light based on an input image signal to form an electrostatic latent image on the charged image carrier 10.

  The developing device 30 (developing unit) generally includes a developer container 31 that stores the liquid developer of each color, a supply roller 35 that applies the liquid developer from the developer container 31 to the developing roller 36, and the like. The electrostatic latent image formed on the image carrier 10 is developed with a liquid developer.

  The intermediate transfer member 40 is configured by an endless belt or the like, is stretched around a driving roller 41 and a tension roller 42, and is rotationally driven by the driving roller 41 while being in contact with the image carrier 10 by the primary transfer unit 50. An intermediate transfer body cleaning unit 46 that removes the developer of the intermediate transfer body 40 by contacting a blade is disposed at a position where the intermediate transfer body 40 is stretched by the tension roller 42.

  In the primary transfer portions 50 of the respective colors, the image carrier 10 and the primary transfer backup roller 51 are arranged to face each other with the intermediate transfer member 40 interposed therebetween, and the contact position with the image carrier 10 is set as a transfer position. Then, the developed toner images of the respective colors on the image carrier 10 are sequentially transferred onto the intermediate transfer member 40 to form a full-color toner image.

  In the secondary transfer unit 60, a secondary transfer roller 61 is disposed to face the driving roller 41 with the intermediate transfer body 40 interposed therebetween. Further, the secondary transfer roller 61 is provided with a secondary transfer roller cleaning unit 62 that removes the developer remaining on the secondary transfer roller 61 with a blade in contact therewith. At the transfer position on the secondary transfer roller 61, the single-color or multiple-color toner images formed on the intermediate transfer body 40 are transferred to a recording material such as paper, film, or cloth conveyed through the sheet material conveyance path L. Is done.

  Further, downstream of the sheet material conveyance path L, a fixing unit is provided for fixing the toner image of a single color or a plurality of colors transferred to a recording material such as paper by applying heat or pressure.

  Next, an image forming unit and a developing device according to an embodiment of the present invention will be described. FIG. 2 is a cross-sectional view illustrating main components of the image forming unit and the developing device 30. Since the configurations of the image forming unit and the developing device for each color are the same, the description is based on the yellow (Y) image forming unit and the developing device, and the subscript alphabet is omitted in the description.

  An image carrier cleaning roller 16, an image carrier cleaning unit 18, a corona charger 11, an exposure unit 12, a developing roller 36, a first squeeze roller 13, and a first squeeze roller are disposed on the outer periphery of the image carrier 10 along the rotation direction. Two squeeze rollers 13 'are arranged.

  On the outer periphery of the developing roller 36, a developing roller cleaning unit 361, a supply roller 35, and a toner compression corona generator 37 are arranged. A regulating member 351 for adjusting the amount of liquid developer supplied to the developing roller 36 is in contact with the supply roller 35. In addition, a supply developer storage unit 311 and a recovered developer storage unit 312 are formed in the liquid developer container 31 in a form partitioned by a wall, and a transport screw 34 is provided in the supply developer storage unit 311. A collection screw 32 (“conveying member” in the present invention) is accommodated in the collected developer storage unit 312.

  A primary transfer roller 51 of the primary transfer unit 50 is disposed along the intermediate transfer body 40 at a position facing the image carrier 10, and an intermediate transfer body squeeze roller 53 and a backup roller 54 are disposed downstream in the moving direction. An intermediate transfer body squeeze portion 52 comprising an intermediate transfer body squeeze roller cleaning portion 55 is disposed.

  The image carrier 10 is a photosensitive drum made of a cylindrical member having an axial length (surface width) longer than that of the developing roller 36 and having a photosensitive layer formed on the outer peripheral surface. Rotate clockwise as shown. The photosensitive layer of the image carrier 10 is composed of an organic image carrier or an amorphous silicon image carrier.

  The corona charger 11 is disposed upstream of the nip portion between the image carrier 10 and the developing roller 36 in the rotation direction of the image carrier 10, and a voltage is applied from a power supply device (not shown) to charge the image carrier 10 to corona. Let In this embodiment, the number of corona chargers 11 is one, but a plurality of corona chargers are arranged along the rotation direction of the image carrier 10 to increase the degree of corona charging and to perform uniform corona charging. Is possible.

  The exposure unit 12 irradiates the image carrier 10 charged by the corona charger 11 with light on the downstream side in the rotation direction of the image carrier 10 from the corona charger 11, and generates an electrostatic latent image on the image carrier 10. Form.

The developing device 30 stores a developing roller 36 (“developer carrier” in the present invention), a supply roller 35 (supply member), and a liquid developer in which toner is dispersed in a carrier at an approximate weight ratio of about 20%. The developer container 31 and the toner compression corona generator 37 that performs a compaction action on the developer are mainly configured.

  The developing device 30 of the present embodiment is configured to supply (apply) the liquid developer directly from the supply roller 35 to the developing roller 36 (two-roller configuration). It is good also as a structure (3 roller structure) apply | coating to an intermediate | middle roller and apply | coating a liquid developer from an intermediate | middle roller to the developing roller 36. FIG. According to such a configuration, the liquid developer is sufficiently kneaded by passing through the nip portion a plurality of times, and a uniform liquid developer film can be formed on the developing roller 36.

  The liquid developer to be replenished to the supply developer storage unit 311 is volatile at room temperature at a low concentration (1 to 2 wt%) and low viscosity using Isopar (trademark: exon) as a carrier, which is generally used conventionally. A solid having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a non-volatile resin having a high concentration and a high viscosity at room temperature instead of a volatile liquid developer having an organic solvent, silicon oil, mineral oil Alternatively, a liquid developer having a high viscosity (about 30 to 10,000 mPa · s) added to a liquid solvent such as edible oil together with a dispersant and having a toner solid content concentration of about 20% is used.

  The supply roller 35 (supply member) has a function of supplying the liquid developer to the developing roller 36. The supply roller 35 is a metal roller having a concave pattern formed by a spiral groove or the like engraved finely and uniformly on the surface so as to easily carry the liquid developer.

  The restricting member 351 is a metal member or a member having elasticity constituted by covering the surface with an elastic body. In the present embodiment, it is composed of a rubber portion made of urethane rubber or the like that comes into contact with the surface of the supply roller 35, and a metal plate or the like that supports the rubber portion. Then, the film thickness and amount of the liquid developer carried and conveyed by the supply roller 35 are regulated and adjusted, and the amount of liquid developer supplied to the developing roller 36 is adjusted.

  The developing roller 36 (“developer carrier” in the present invention) is a cylindrical member. In this embodiment, the developing roller 36 rotates counterclockwise around the rotation axis as shown in the figure, and the surface thereof is the developing roller. It rotates so as to move in the direction opposite to the surface 36 and rotates so as to move in the same direction as the surface of the image carrier 10. In order to form an image, the rotation direction of the developing roller 36 needs to be rotated so that the surface thereof moves in the same direction as the surface of the image carrier 10. In the same direction, it may be configured to move in either direction.

  The developing roller 36 is provided with an elastic layer such as polyurethane rubber, silicon rubber, NBR, or PFA tube on the outer periphery of an inner core made of metal such as iron. The developing roller cleaning unit 361 that contacts the surface of the developing roller 36 (“cleaning unit” in the present invention) is made of an elastic body such as rubber, and the developing roller from the developing nip that the developing roller 36 contacts the image carrier 10. The liquid developer disposed on the downstream side of the rotation direction 36 and remaining on the developing roller 36 is scraped off and removed.

  The toner compression corona generator 37 is an electric field applying unit that increases the charging bias on the surface of the developing roller 36, and the toner of the liquid developer conveyed by the developing roller 36 is positioned close to the toner compression corona generator 37. Then, an electric field is applied, and charging and compression are performed. For the toner charging and compression, a compaction roller that is charged by contact may be used instead of corona discharge by applying electrolysis.

The charged and compressed liquid developer carried on the developing roller 36 is developed corresponding to the electrostatic latent image on the image carrier 10 at the development nip where the developing roller 36 and the image carrier 10 abut. After passing through the developing nip portion, the developer that has not contributed to the development is scraped off by the developing roller cleaning unit 361 and dropped into the collected developer storage unit 312.

Two squeeze members are provided on the downstream side of the developing roller 36 and the upstream side of the primary transfer unit 50 for collecting excess developer of the toner image developed on the image carrier 10. Each of the squeeze members is coated with an elastic body and has first and second squeeze rollers 13 and 13 ′ formed of an elastic roller that is slidably contacted with the image carrier 10 and is pressed against the squeeze rollers 13 and 13 ′. The first and second squeeze roller cleaning units 131 and 131 ′ for cleaning the surface in contact with each other, and collecting excess carrier liquid from the developer developed on the image carrier 10;
It has the function of increasing the toner particle ratio in the visible image.

  In the present embodiment, two squeeze members are arranged before the primary transfer. However, the number of squeeze members is not limited to two, and an appropriate number can be arranged. Further, each squeeze member may be configured to be switched to abut or separate from the image carrier 10 depending on the state of the liquid developer.

  In the primary transfer unit 50, the image developed on the image carrier 10 is transferred to the intermediate transfer member 40 by the primary transfer backup roller 51. Here, by moving the image carrier 10 and the intermediate transfer member 40 at a constant speed, it is possible to reduce the driving load of rotation and movement, and to suppress the disturbance effect on the toner image of the image carrier 10. is there.

  The image carrier cleaning device disposed on the downstream side of the primary transfer faces the image carrier 10 and is disposed on the downstream side of the primary transfer unit 50, thereby developing the transfer residual liquid on the image carrier 10. Cleaning agent and untransferred liquid developer. A bias voltage that attracts toner particles in the liquid developer is applied to the image carrier cleaning roller 16. Therefore, what is collected by the image carrier cleaning roller 16 is a liquid developer containing a large amount of toner particles. The liquid developer rich in solid content collected by the image carrier cleaning roller 16 is scraped off by the image carrier cleaning roller cleaning unit 17 in contact with the image carrier cleaning roller 16 and falls vertically downward.

  The intermediate transfer body squeeze device 52 includes an intermediate transfer body squeeze roller 53 formed of an elastic roller member that covers an elastic body and rotates in sliding contact with the intermediate transfer body 40, and the intermediate transfer body squeeze roller sandwiching the intermediate transfer body 40. 53, and a cleaning unit 55 that presses and contacts the intermediate transfer member squeeze roller 53 to clean the surface, and removes excess carrier from the developer primarily transferred to the intermediate transfer member 40. Has the function of collecting.

  The developing device and the image forming apparatus according to the embodiment of the present invention have been described above. Next, the liquid developer in the developer container 31 according to the embodiment of the present invention will be described with reference to FIGS. The flow will be described.

FIG. 3 is a cross-sectional view taken along a plane perpendicular to various rollers (between BB ′ shown in FIG. 4) in the developing device 30 according to the embodiment of the present invention. FIG. 4A shows a cross-sectional view of the developer container 31 in the collected developer storage portion 312 (between AA ′ shown in FIG. 3). FIG. 4B shows a top view of the developer container 31 of FIG. FIG. 5 is a view showing the state of the liquid developer in the collected developer storage unit 312 of the conventional developer container 31.

As shown in FIG. 3, in the developer container 31, a supply developer storage unit 311 for storing the liquid developer supplied from the supply port 313 and a recovered developer storage unit 312 for recovering the liquid developer. The supplied developer storage part 311 and the recovered developer storage part 312 are partitioned by a wall part 314. At both ends of the wall portion 314, as shown in FIG.
A first recovery port 315 and a second recovery port 315 ′ formed by cutting out a part of the upper end are provided. The liquid level in the supplied developer reservoir 311 is kept constant by the height of the recovery ports at both ends.

  A liquid developer whose concentration is adjusted is stored from a supply port 313 in a supply developer storage unit 311 that stores a liquid developer to be used for development. A transport screw 34 is disposed in the supply developer storage unit 311, and the liquid developer is stirred and transported in the axial direction by rotation thereof. In the present embodiment, the conveying direction of the conveying screw 34 is different with the replenishing port 313 as a boundary, and the liquid developer flowing from the replenishing port 313 flows in both the left and right directions as indicated by arrows in FIG. It is conveyed to.

As described above, the liquid developer transported in the left and right directions by the transport screw 34 in the supply developer storage unit 311 is provided with a first recovery port 315 and a second recovery port provided one step lower on the left and right sides of the wall 314. Overflow from 315 ′ to the collected developer storage unit 312 side. With such a configuration, the liquid level in the supply developer reservoir 311 can be maintained, and the liquid developer can be supplied uniformly to the supply roller 34. The liquid developer may be overflowed over the entire wall portion 314 by adjusting the amount of liquid developer supplied from the supply port 311.

The liquid developer overflowed to the collected developer storage unit 312 is unidirectionally (from right to left in the figure) by a collection screw 32 (corresponding to the “conveying member” of the present application) disposed in the collected developer storage unit 312. ) And flows out from the first conveyance hole 331 opened in the collected developer storage unit 312. The first transport hole 331 communicates with a tubular transport channel 33 having a second transport hole 332 at the other end. The recovery screw 32 is also disposed in the transport flow path 33, and the liquid developer is transported also in the recovery screw 32. The liquid developer discharged from the second transport hole 332 is reused after the toner concentration is adjusted by the developer supply unit. In such a developing device 30, particularly when the developing device 30 is operated after being stopped for a long period of time, the developer adhering to the developing roller cleaning unit 361 or the like falls, and the inside of the collected developer storing unit 312. It is in a state of being accumulated at. When the developing device 30 is started in this state, the developer accumulated in the collected developer storage unit 312 is drawn to the first transport hole 331 at a stretch, and the transport in the transport flow path 33 is not in time.

  Therefore, in the vicinity of the first transport hole 331, the liquid developer level becomes high, and the liquid developer recovered from the first recovery port 315 backflows or overflows from the developer container 31. There is a case. When the liquid developer flows backward, the adjusted concentration of the liquid developer in the supply developer reservoir 311 is disturbed. Further, the recovered liquid developer may be solidified, and when such a liquid developer flows backward to the supply developer storage unit 311, clogging occurs in the recess pattern of the supply roller 35, thereby forming an image. Will be hindered. When overflowing from the developer container 31, the inside of the machine is soiled, and similarly, image formation is hindered.

  FIG. 5 is a diagram illustrating a flow of the liquid developer in the collected developer storage unit 312 in the conventional developing device. The figure is a cross-sectional view of the developing device 30 in the vicinity of the recovery screw 32. The collection screw 32 is a member in which a spiral fin is formed around an axis, and is a member disposed in communication with the collection developer storage unit 312 and the conveyance channel 33. The collection screw 32 rotates around the axis to convey the liquid developer in the direction indicated by the arrow in the drawing.

Behind the collection screw 32, a wall portion 314 for partitioning from the supplied developer storage portion 311 is disposed. A first recovery port 315 and a second recovery port 315 ′ for overflowing the liquid developer from the supply developer storage unit 311 are opened at both ends of the wall portion 314. A supply roller 35 and a development roller 36 are disposed on the supply developer storage unit 311 side.

The ratio of the amount of liquid developer recovered in the recovered developer storage unit 312 is as follows. Assuming that the amount of liquid developer required to form a thin film on the developing roller 36 is V0, the liquid developer Vd supplied to the supply developer reservoir 311 has a margin Vd = 1.3 * V0. A degree is required. Therefore, the amount obtained by dividing the margin by two is the collected amount Q1 from the first collection port 315 and the collected amount Q3 from the second collection port 315 ′, respectively.
Will overflow.

  On the other hand, of the supplied liquid developer Vd, the amount Q2 of the liquid developer that does not adhere to the developed image carrier 10 and is scraped and collected by various cleaning units varies depending on the print pattern. It becomes about 0.5 * V0. As shown in the figure, the recovered liquid developer is recovered over the entire width direction of the recovered developer storage unit 312, and thus the recovered amount increases as it approaches the transport direction side.

  As described above, the collected developer storage unit 312 collects the liquid developer in a total amount of about Q1 + Q2 + Q3 = 0.8 * V0. In this embodiment in which the liquid developer recovered in one direction is transported, the recovered amount is maximized in the vicinity of the inlet of the first transport hole 331 as shown in the drawing.

  On the other hand, a joint portion is required in the vicinity of the second transport hole 332 in order to attach and detach the transport channel 33 for maintenance or the like. Usually, in such a joint portion, a leak prevention valve or the like is disposed, so that a portion where the tube becomes narrow is generated, and the pipeline resistance in the transport flow path 33 increases.

  Thus, in the vicinity of the first recovery port 315 where both the recovery amount and the pipe resistance increase, the liquid level of the liquid developer tends to rise, and when the height of the first recovery port 315 is exceeded as shown in the figure, It will flow back to the supply developer storage unit 311 side, causing various problems as described above.

  In the present invention, in order to solve the problem associated with the rise in the liquid level in the vicinity of the first recovery hole 331, a difference in transport force is provided for each transport portion of the recovery screw 32 ("transport member" in the present invention). It is characterized by this. In this way, the simple configuration of partially changing the shape of the recovery screw 32 can solve the various problems described above at a low cost without increasing the size of the apparatus, and is inexpensive and reliable. High-quality products can be provided to users.

  FIG. 6 is a view showing a first embodiment in which the collection screw 32 is provided with a plurality of conveyance units having different conveyance amounts. Liquid development in the transport section (B section) of the recovery screw 32 in the collected developer storage section 312 with respect to the transport amount of the liquid developer in the transport section (section A) of the recovery screw 32 located in the transport flow path 33 The transport amount of the agent is made small. With such a configuration, it is possible to lower the liquid level in the vicinity of the first recovery port 315 in the recovered developer storage unit 312, the backflow of the liquid developer from the first recovery port 315, and the developer container 31. It is possible to prevent overflow of the liquid developer.

  Now, the conveyance amount (conveyance capability) of the recovery screw 32 (“conveyance member” in the present invention) will be described with reference to FIGS. Various forms for transporting the liquid developer can be selected for the transport member in the present invention. Here, how to vary the transport amount when the screw shape is adopted for the transport member will be described in detail.

  FIG. 7 is an enlarged view of various forms of the recovery screw 32. FIG. 8 is a view showing various parameters of the screw shape of the recovery screw 32. FIG. 9 is a diagram showing the transport amount when the lead angle, which is one parameter of the screw shape, is changed.

  Each of the three recovery screws 32 shown in FIG. 7 has the same number of strips (the number of turns of the spiral), the lead angle (the angle formed by the spiral with the axis vertical plane), and the pitch (the axial direction when the spiral rotates once). The distance to is different. The conveyance amount of the recovery screw 32 mainly depends on the lead angle.

  FIG. 9 is a graph showing the conveyance amount with respect to the lead angle. The conveyance amount is maximized in the vicinity where the lead angle is 30 °. Therefore, in the various screw shapes in FIG. 7, the transport amounts have a relationship of (a)> (b)> (c). In this way, it is possible to vary the conveyance amount depending on the screw shape.

  As described above, the embodiment in which the lead amount, the pitch, and the number of strips are changed to change the transport amount has been described for the transport member in the case of adopting the screw shape. In addition, it is possible to give a difference in the conveyance amount by making the material (rigidity) of the screw different. Further, when the collection screw 32 is divided and rotated independently by a plurality of shafts, the rotation speed of each collection screw 32 may be varied to give a difference in the conveyance amount.

  FIG. 10 is a diagram showing a second embodiment in which the recovery screw 32 is provided with a plurality of conveyance units having different conveyance amounts. This embodiment differs from the first embodiment in that a difference is provided in the conveyance amount for each conveyance unit in the collected developer storage unit 312. Specifically, in the collection screw 32 in the collected developer storage unit 312, the conveyance amount at the lower position (B portion) of the first collection port 315 is smaller than the conveyance amount in the other portion (C portion). is doing. According to such a configuration, it is possible to actively lower the rise in the liquid level in the vicinity of the first recovery port 315 where the liquid level is likely to rise.

  The conveyance amount in the B portion may be a negative value (the direction opposite to the original conveyance direction, the right direction in the figure). The liquid developer in part B is transported in the original direction by the transport force of part C, but the liquid level in the vicinity of the first recovery port 315 is made negative by the transport direction in part B. Can be further reduced.

  Further, in the present embodiment, in the part C, by setting the pitch of the recovery screw 32 to be short, the shearing force of the recovery screw 32 is increased and the solidified liquid developer is finely crushed, and then the downstream part B, You may make it convey to A part.

  FIG. 11 is a diagram illustrating a third embodiment in which the recovery screw 32 is provided with a plurality of conveyance units having different conveyance amounts. In the second embodiment, the width of the B part is set to substantially match the width of the first recovery port 315, whereas in this embodiment, the width of the B part is set to be greater than the width of the first recovery port 315. It is also assumed to be set short. As described above, the width of each part in the recovery screw 32 is not limited to the B part, and can be appropriately set according to the amount of liquid developer. Further, switching of the conveyance amount between the respective units may be performed so that the conveyance amount continuously changes.

FIG. 12 is a view showing a fourth embodiment in which the collection screw 32 is provided with a plurality of conveyance units having different conveyance amounts. In this embodiment, the second recovery port 315 ′ is further added to the second embodiment.
The carry amount at the lower position (D section) is made larger than the carry amount at the C section located downstream thereof. According to this configuration, the liquid level in the vicinity of the second recovery port 315 ′ having a relatively large amount of liquid is kept low, the back flow from the second recovery port 315 ′ and the liquid developer overflowing in the vicinity. It becomes possible to prevent.

  As described above, the present invention has a simple configuration in which the transport amount of the transport member disposed in the collected developer storage unit 312 and the transport flow path 33 is changed for each transport unit, and the liquid development can be performed without increasing the size of the apparatus. It is possible to prevent the back flow and overflow of the agent and to form a high quality image.

  Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments also fall within the scope of the present invention. Is.

DESCRIPTION OF SYMBOLS 10 ... Image carrier, 11 ... Corona charger, 12 ... Exposure unit, 13 ... 1st squeeze roller, 131 ... 1st squeeze roller cleaning part, 13 '... 2nd squeeze roller, 131' ... 2nd squeeze roller cleaning part 16 ... Image carrier cleaning roller, 17 ... Image carrier cleaning roller cleaning unit, 18 ... Image carrier cleaning unit,
DESCRIPTION OF SYMBOLS 30 ... Developing device (developing part), 31 ... Developer container, 311 ... Supply developer storage part, 312 ... Collected developer storage part, 314 ... Wall part, 315 ... 1st collection port, 315 '... 2nd collection port 32 ... Recovery screw, 33 ... Conveyance channel, 331 ... First conveyance hole, 332 ... Second conveyance hole, 34 ... Conveyance screw, 35 ... Supply roller, 351 ... Restriction member, 36 ... Development roller, 361 ... Development roller Cleaning unit 37 ... Toner compression corona generator,
40 ... Intermediate transfer member, 41 ... Driving roller, 42 ... Tension roller, 46 ... Intermediate transfer member cleaning unit,
50... Primary transfer section 51. Primary transfer backup roller 52. Intermediate transfer body squeeze section 53. Intermediate transfer body squeeze roller 54 54 Intermediate transfer body squeeze backup roller 55 55 Intermediate transfer body squeeze roller cleaning section
60 ... secondary transfer unit, 61 ... secondary transfer roller, 62 ... secondary transfer roller cleaning unit

Claims (8)

A supply developer reservoir for storing a liquid developer having toner and carrier liquid;
A developer carrier that carries and rotates the liquid developer;
A cleaning unit that contacts the developer carrier and collects the liquid developer;
A recovered developer storage section for storing the liquid developer recovered by the cleaning section;
A transport flow path connected to the recovered developer storage section;
A developing device comprising: a transport member having a transport section disposed in the recovered developer storage section and the transport flow path and having a transport amount of the liquid developer different from each other. The transport member includes a first transport unit disposed in the transport channel, and a second transport unit disposed in the vicinity of the transport channel inlet of the recovered developer storage unit and in the vicinity of the transport channel. Have
The developing device according to claim 1, wherein a transport amount of the liquid developer of the second transport unit is smaller than a transport amount of the liquid developer of the first transport unit. A wall portion disposed between the recovered developer storage portion and the supply developer storage portion;
The developing device according to claim 1, further comprising: a recovery port that is disposed on the wall portion and causes the liquid developer stored in the supply developer storage portion to flow into the recovery developer storage portion.   The said collection | recovery port has the 1st collection | recovery port arrange | positioned in the conveyance direction side of the said conveyance member, and the 2nd collection port arrange | positioned in the reverse direction side with respect to the conveyance direction of the said conveyance member. Development device. The transport member has a third transport unit disposed on the opposite side of the transport direction with the second transport unit,
The developing device according to claim 4, wherein a transport amount of the liquid developer of the second transport unit is smaller than a transport amount of the liquid developer of the third transport unit. The transport member has a fourth transport unit disposed on the opposite side of the transport direction with the third transport unit,
The developing device according to claim 5, wherein a transport amount of the liquid developer of the fourth transport unit is larger than a transport amount of the liquid developer of the third transport unit.   The said 1st conveyance part and the said 2nd conveyance part are any one of the Claims 1 thru | or 6 which are screw shapes from which at least 1 differs among a lead angle, pitch, the number of strips, a material, and the magnitude | size of a diameter. The developing device according to 1. A supply developer reservoir for storing a liquid developer having a toner and a carrier liquid, a developer carrier that rotates while supporting the liquid developer, and a liquid developer that contacts the developer carrier and collects the liquid developer A cleaning unit, a collected developer storing unit for storing the liquid developer recovered by the cleaning unit, a transport channel connected to the recovered developer storing unit, and a transport channel connected to the recovered developer storing unit and the transport channel. A developing unit having a transport member having transport units with different transport amounts;
And an image carrier that is developed by the developer carrier.

Images