JP2009156935A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming method, adjusting the quantity of a developer charged in a simple constitution without adding any new charge quantity adjusting mechanism. <P>SOLUTION: The charge quantity of a liquid developer containing a developer solid part and a nonvolatile liquid carrier is detected, and according to the detection result, a flow of the recovered liquid developer on a developer support 20Y moving from a first carrying passage 85 to a first storing part 81Y and a flow of the developer moving from a second carrying passage 91 to a second storing part 93 are adjusted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, a liquid developer is supplied to a developer carrier by a developer supply roller, a latent image on the image carrier is developed by the developer carrier, and an image on the image carrier is transferred to an intermediate transfer member. The present invention relates to an image forming apparatus and an image forming method for forming an image by secondary transfer of an image on an intermediate transfer member to a transfer material.

  Conventionally, it is known that the charge amount of a liquid developer is likely to change over time. When the charge amount changes, the charge amount generally tends to decrease. On the other hand, in the known example, by applying a stress load to the liquid developer as a method for preventing a change in the charge amount, a chemical non-equilibrium state of the liquid developer is caused to stabilize the charge amount. A method has been proposed (see Patent Document 1).

JP 2003-50511 A

  However, in the invention described in Patent Document 1, a stress applying device must be prepared for each color, which makes the device more complex and larger.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus and an image forming method that can adjust the charge amount of a developer with a simple configuration without adding a new charge amount adjustment mechanism. To do.

  The present invention provides an image forming apparatus that solves the above-described problems, a developer carrying member carrying a liquid developer containing developer solids and a liquid carrier, and an image in which a latent image is developed by the developer carrying member. A carrier, an intermediate transfer member that forms an image by transferring an image on the latent image carrier, a secondary transfer unit that transfers an image on the intermediate transfer member to a transfer material, and an image on the transfer material. A fixing unit for fixing, a collecting unit for collecting the liquid developer on the developer carrying member, a first storage unit and a second storing unit for storing the liquid developer collected by the collecting unit, and the collecting unit A first transport path in which the recovered liquid developer moves to the first storage section, a second transport path in which the liquid developer recovered by the recovery means moves to the second storage section, the first transport path, and the first 2 Adjust the flow rate of the liquid developer moving along the transport path. And a charge amount detection means for detecting the charge amount of the liquid developer, and the adjustment means is controlled according to the detection result of the charge amount detection means, so that a new charge amount adjustment mechanism is not added. The charge amount of the developer can be adjusted with a simple configuration.

  Further, since the charge amount detection means detects the charge amount from the current value when the developer is electrophoresed from the developer carrier to the latent image carrier, the charge amount of the developer is adjusted with a simple configuration. can do.

  Further, since the charge amount detection means detects a current that flows when a solid image is printed on the image carrier, it is easy to detect the current value of the developer solid content.

  Further, since the solid image is longer than the nip width between the developer carrier and the image carrier, the detection of the current value is stable.

  Further, since the charge amount detection means detects the density of the image printed on the intermediate transfer member, the charge amount of the developer can be adjusted with a simple configuration.

  The first storage unit includes a recycled developer storage unit that recycles the liquid developer recovered by the recovery unit, and the second storage unit discards the liquid developer recovered by the recovery unit. Since the developer storage unit is provided, the ratio between the liquid developer to be recycled and the liquid developer to be discarded can be adjusted, and the charge amount can be adjusted efficiently and accurately.

  The developer carrier, the latent image carrier, the recovery unit, the first storage unit, the first transport path, the adjustment unit, and the charge amount detection unit are provided corresponding to a plurality of colors. Therefore, the charge amount can be adjusted efficiently and accurately corresponding to a plurality of colors.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing main components constituting an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing components for each color of the image forming apparatus. In FIG. 1, for yellow (Y), magenta (M), cyan (C), and black (K), only yellow (Y) is indicated by Y. Of these, FIG. 2 specifically shows the configuration of yellow (Y). The image forming apparatus will be described below with reference to FIGS.

  The image forming apparatus 1 includes a latent image carrier cleaning device including a latent image carrier cleaning blade 16Y and a latent image carrier developer recovery unit 17Y along the rotation direction (movement direction) of the outer periphery of the latent image carrier 10Y. The developing roller 20Y as an example of the developer carrying member of the charging roller 11Y, the exposure unit 12Y, and the developing unit 30Y, the latent image carrying member squeeze roller 13Y, and the squeeze roller cleaning blade 14Y and the squeeze roller developer collecting unit 15Y that are associated with the developing roller 20Y. A cleaning device is arranged. The developing unit 30Y includes a developing roller cleaning blade 21Y and a developer supplying roller 32Y using an anilox roller as an example of a developer supplying member on the outer periphery of a developing roller 20Y as a developer carrying member, and a developer supply amount thereof. A regulating blade 33Y for regulating is disposed, and a developer agitating roller 34Y for agitating the developer in a uniformly dispersed state is disposed in a developer container (reservoir) 31Y in which the liquid developer is accommodated.

  In addition, a primary transfer roller 51Y of the primary transfer unit 50Y is disposed at a position facing the latent image carrier 10Y with an intermediate transfer belt 40 as an example of an intermediate transfer member interposed therebetween. Further, primary transfer portions 50Y (M, C, K) for the respective colors are further arranged. A secondary transfer unit 60 is disposed downstream of the primary transfer unit 50Y (M, C, K), and an image is transferred to a transfer material. A fixing unit 70 is disposed on the downstream side of the transfer material conveyance path L from the secondary transfer unit 60. The fixing unit 70 includes a heating roll 71 and a pressure roll 72, and fixes the image on the transfer material.

  The liquid developer contained in the developer container 31Y is composed of resin fine particles containing a pigment component, a dispersant, and a non-volatile liquid carrier, and is an average in which a colorant such as a pigment is dispersed in a thermoplastic resin. High viscosity (about 30 to 10000 mPa · s) in which solid particles having a particle diameter of 1 μm are added together with a dispersant to a liquid solvent such as an organic solvent, silicon oil, mineral oil, or edible oil, and the toner solid content concentration is about 25%. ) Liquid developer. The liquid developer contained in the developer container 31Y is a developer or carrier dispersed in a high concentration of about 35 to 55% by weight of the toner according to the developer concentration that changes with development on the latent image carrier. Each is replenished to the developer container 31Y and stirred by the liquid developer stirring roller 34Y to obtain a uniformly dispersed state, and 25% of the toner is dispersed in 75% of the carrier in an approximate weight ratio.

  In the vicinity of the latent image carrier 10Y and the developing unit 30Y, the latent image carrier 10Y is uniformly charged by the charging roller 11Y, and the exposure unit 12Y having an optical system such as a semiconductor laser, a polygon mirror, and an F-θ lens is used. Based on the input image signal, a modulated laser beam is irradiated to form an electrostatic latent image on the charged latent image carrier 10Y. Then, the amount of developer supplied is regulated by the regulating blade 33Y from the developer container 31Y that stores the liquid developer of each color (here yellow), and the developer is supplied from the developer supply roller 32Y to the developing roller 20Y to form a latent image. The electrostatic latent image formed on the carrier 10Y is developed.

  As shown in FIG. 3, the developer supply roller 32 </ b> Y is a cylindrical member, and an anilox having an uneven surface formed by fine and uniform spiral grooves on the surface so as to easily carry the developer on the surface. For example, as shown in FIG. 2, the roller rotates in the clockwise direction. The groove dimensions are such that the groove pitch is about 130 μm and the groove depth is about 30 μm. The developer supply roller 32Y supplies the liquid developer from the developer container 31Y to the developing roller 20Y. The stirring roller 34Y and the developer supply roller 32Y may be in sliding contact with each other, but may be in a distant relationship.

  The developer regulating blade 33Y is composed of an elastic blade having a surface covered with an elastic body, a rubber portion made of urethane rubber or the like that comes into contact with the surface of the developer supply roller 32Y, and a metal plate or the like that supports the rubber portion. Composed. Then, the film thickness and amount of the liquid developer carried and conveyed by the developer supply roller 32Y composed of an anilox roller are regulated and adjusted, and the amount of liquid developer supplied to the developing roller 20Y is adjusted. Note that the rotation direction of the developer supply roller 32Y may be the opposite direction instead of the arrow direction shown in FIG. 2, and the developer regulating blade 33Y at that time requires an arrangement corresponding to the rotation direction.

  The developing roller 20Y is a cylindrical member having a width of about 320 mm, and rotates counterclockwise around the rotation axis as shown in FIG. The developing roller 20Y is provided with an elastic layer made of polyurethane rubber, silicon rubber, NBR or the like on the outer periphery of an inner core made of metal such as iron. The developing roller cleaning blade 21Y is made of rubber or the like that comes into contact with the surface of the developing roller 20Y, and is arranged downstream of the developing nip portion where the developing roller 20Y comes into contact with the latent image carrier 10Y in the rotation direction of the developing roller 20Y. The liquid developer remaining on the developing roller 20Y is scraped off and removed.

  As shown in FIG. 4, the developer D carried on the developing roller 20Y is converted into a latent image on the latent image carrier 10Y by applying a desired electric field at the developing nip where the developing roller 20Y contacts the latent image carrier 10Y. Correspondingly developed. The undeveloped developer D is scraped off and collected by the developing roller cleaning blade 21Y.

  The intermediate transfer belt 40 is an endless belt member and is wound around and stretched between a driving roller 41 and a tension roller 42, and the latent image carriers 10Y, 10M, and 50K are primary transfer units 50Y, 50M, 50C, and 50K. It is rotationally driven by the drive roller 41 while abutting 10C and 10K.

  The primary transfer units 50Y, 50M, 50C, and 50K are arranged so that the primary transfer rollers 51Y, 51M, 51C, and 51K face the latent image carriers 10Y, 10M, 10C, and 10K with the intermediate transfer belt 40 interposed therebetween. The developed toner image of each color on the latent image carriers 10Y, 10M, 10C, and 10K is sequentially superimposed and transferred onto the intermediate transfer belt 40 using the contact position with 10Y, 10M, 10C, and 10K as a transfer position. A full-color toner image is formed.

  The intermediate transfer belt 40 sequentially carries the toner images formed on the plurality of latent image carriers (photoconductors) 10Y, 10M, 10C, and 10K in such a manner that they are sequentially transferred onto the transfer material. Next transfer.

  In the secondary transfer unit 60, a secondary transfer roller 61 is disposed opposite to the belt driving roller 41 with the intermediate transfer belt 40 interposed therebetween, and further includes a secondary transfer roller cleaning blade 62 and a secondary transfer roller developer collecting unit 63. A next transfer roller cleaning device is arranged. In the secondary transfer unit 60, the transfer material conveyance path L is synchronized with the timing at which a full-color toner image or a single-color toner image formed on the intermediate transfer belt 40 is overlaid on the intermediate transfer belt 40 reaches the transfer position of the secondary transfer unit 60. Then, a transfer material such as paper, film or cloth is conveyed and supplied, and a single color toner image or a full color toner image is secondarily transferred to the transfer material.

  A fixing unit 70 is disposed downstream of the transfer material conveyance path L of the secondary transfer unit 60. The fixing unit 70 fuses and fixes a single-color toner image or a full-color toner image transferred onto the transfer material to a recording medium (transfer material) such as paper, and ends the final image formation on the transfer material. .

  On the side of the tension roller 42 that stretches the intermediate transfer belt 40 together with the belt driving roller 41, the intermediate transfer belt cleaning blade 43 that contacts the intermediate transfer belt 40 along the outer periphery thereof, and the intermediate transfer belt cleaning blade 43 cleaned. An intermediate transfer belt cleaning device including an intermediate transfer belt developer recovery unit 44 that recovers the developer is disposed. The intermediate transfer belt 40 that has passed through the secondary transfer unit 60 is cleaned on the intermediate transfer belt 40 by the cleaning blade 43, and then heads toward the primary transfer unit 50 again.

  In the developer container 31Y, the toner particles in the liquid developer have a positive charge. The developer is agitated by the agitation roller 34Y to be in a uniformly dispersed state, and the developer supply roller 32Y rotates. The developer is pumped up from the developer container 31Y, the developer amount is regulated by the regulating blade 33Y, and supplied to the developing roller 20Y. Initially, the developer stored in the developer container 31Y is uniformly dispersed in the carrier at a toner weight ratio of about 25%. However, the development on the latent image carrier 10Y has a high image duty. In this case, the consumption ratio of the toner is large. Conversely, in the case of development with a low image duty, the consumption ratio of the toner is small. In other words, the toner weight ratio of the developer stored in the developer container 31Y changes with development on the latent image carrier 10Y, and this change is constantly monitored and dispersed to an approximate toner weight ratio of about 25%. It is necessary to maintain and control the state.

  In order to control the density of the developer in the developer container 31Y, as a means for detecting the density, a transmission type photosensor for detecting the dispersion weight ratio of the toner (not shown) or torque detection for detecting the stirring torque of the developer stirring roller 34Y. Each developing unit 30Y is provided with a reflection type photosensor for detecting the means and the developer liquid level in the developer container 31Y. When the toner dispersion weight ratio decreases at a predetermined developer amount, the developer dispersed at a high concentration of about 35 to 55% is added from the high concentration developer tank 83Y to the developer container 31Y. Add a fixed amount. Conversely, when the toner dispersion weight ratio increases, a predetermined amount of carrier is replenished from the carrier oil tank 87Y to the developer container 31Y. By these replenishment, the toner weight ratio is controlled to about 25%.

  In order to exhibit a preferable secondary transfer function and a fixing function in a stage where an image is formed through various process steps, is secondarily transferred to a final transfer material, and proceeds to a fixing step (not shown) using this developer. It is desirable that the liquid developer is in a dispersion state of approximately 40% to 60% in approximate toner weight ratio. For this reason, the image forming apparatus according to the present exemplary embodiment includes a developer collecting unit that removes and collects excess developer and excess carrier at a plurality of positions as appropriate.

  Next, the developer recovery unit will be described. In the image forming apparatus according to the present exemplary embodiment, the developer is scraped off and collected by a cleaning device included in the developer collecting unit. As the developer recovery means, a developing roller cleaning device 21 for cleaning the developing roller 20, a latent image carrier squeeze device 13-15, a latent image carrier cleaning device 16, 17, an intermediate transfer belt cleaning device 43-44, and Includes secondary transfer roller cleaning devices 62, 63 and the like.

  The developing unit 30Y includes a developing roller cleaning blade 21Y as an example of a developing roller cleaning device that cleans the developing roller 20Y. The developing roller cleaning blade 21Y is disposed downstream of the developing nip where the developing roller 20Y contacts the latent image carrier 10Y in the rotational direction of the developing roller 20Y, and scrapes off and removes the developer remaining on the developing roller 20Y. To do.

  As shown in FIG. 6, the squeeze devices 13Y to 15Y have a squeeze roller 13Y made of an elastic roller member that covers an elastic body 13-1Y on its surface and rotates in sliding contact with the latent image carrier 10Y. Thus, the squeeze roller cleaning blade 14Y that presses and slides against the squeeze roller 13Y to clean the surface, and the squeeze roller developer recovery unit 15Y are configured.

  The squeeze device 13 has a function of collecting excess carrier liquid C and originally unnecessary fog toner T ″ from the developer D developed on the latent image carrier 10Y and increasing the ratio of toner particles in the visible image. The recovery capability of the liquid C can be set to a desired recovery capability based on the rotation speed of the squeeze roller 13Y and the relative peripheral speed difference of the surface of the squeeze roller 13Y with respect to the peripheral speed of the surface of the latent image carrier 10Y. When the image carrier 10Y is rotated in the counter direction, the collection capability increases. Even if the peripheral speed difference is set large, the collection capability increases, and this synergistic effect is also possible.

  In the primary transfer unit 50Y, the latent image carrier 10Y and the intermediate transfer belt 40 move at the same speed, and the developer image developed on the latent image carrier 10Y is transferred to the intermediate transfer belt 40 by the primary transfer roller 51Y. In addition, the driving load of rotation and movement is reduced, and the disturbance effect on the visible toner image of the latent image carrier 10Y is suppressed. The primary transfer portion 50Y for the first color does not cause a color mixing phenomenon because it is the first primary transfer, but since the second and subsequent colors transfer different color toner images onto the already transferred primary toner image portions, the intermediate transfer belt 40 is overlapped. The reverse transfer development causes the toner to transfer from the toner to the latent image carrier 10Y (M, C, K), and the reverse transfer toner and the untransferred toner are mixed to form a latent image carrier 10Y (M, C, K) together with the surplus carrier. The latent image carrier 10Y (M, C, K) moves from the latent image carrier 10Y (M, C, K) by the action of the latent image carrier cleaning blade 16Y (M, C, K) as an example of a latent image carrier cleaning device. The developer is collected by the developer collecting unit 17Y (M, C, K).

  The transfer material is supplied in accordance with the timing at which the toner image superimposed on the intermediate transfer belt 40 reaches the secondary transfer portion, and the toner image is secondarily transferred to the transfer material and proceeds to the fixing process to be finally transferred. The above image formation is completed, but if a transfer material supply trouble such as a jam occurs, not all the toner images are transferred to the secondary transfer roll and collected, and some of them are on the intermediate transfer belt. In addition, in the normal secondary transfer process, the toner image on the intermediate transfer belt 40 is not 100% secondarily transferred and transferred to the transfer material, but a secondary transfer residue of several percent occurs. In particular, when a transfer material supply trouble such as a jam occurs, the toner image is transferred in contact with the secondary transfer roller 61 without the transfer material interposed therebetween, causing the back surface of the transfer material to become dirty. These unnecessary toner images are cleaned on the intermediate transfer belt 40 by the intermediate transfer belt cleaning blade 43 of the intermediate transfer belt 40 and the secondary transfer roller 61 by the secondary transfer roller cleaning blade 62 of the secondary transfer roller 61. . As described above, the secondary transfer roller cleaning blade 62 is provided as means for removing the developer (toner dispersed in the carrier) transferred to the secondary transfer roller 61, and the developer is collected from the secondary transfer roller 61. .

  Next, a recycling apparatus 80 for recycling the collected liquid developer will be described. Note that FIG. 1 shows a yellow-only liquid developer recycling apparatus 80Y, and the other color liquid developer recycling apparatuses 80M, 80C, and 80K having the same structure are omitted.

  As shown in FIG. 1, 80Y is a recycling device, 81Y is a recycled developer storage unit as a first storage unit, 82Y is a recycling agitation roller, 83Y is a high-concentration developer tank, 84Y is a pump for high-concentration developer, 85Y Denotes a developing roller recycling path as a first conveying path, 86Y denotes a developing roller recycling pump as an adjusting means, 87Y denotes a carrier oil tank, and 88Y denotes an open / close valve.

  In the present embodiment, a developing roller recycling path 85Y is provided that collects the developer scraped and collected by the developing roller cleaning blade 21Y and connects to the recycled developer storage unit 81Y via the developing roller recycling pump 86Y.

  The replenishment of the high-concentration developer is performed by replenishing the recycle developer storage unit 81Y from the high-concentration developer tank 83Y via the high-concentration developer pump 84Y. Further, the replenishment of the carrier oil is performed by replenishing the recycle developer reservoir 81Y from the carrier oil tank 87Y via the opening / closing valve 88Y. These replenishments are executed according to the developer concentration in the recycled developer storage unit 81Y measured by a density sensor (not shown) or the like. The developer in the recycled developer storage unit 81Y is adjusted to a uniform density by the rotation of the recycle stirring roller 82Y, replenished to the developer container 31Y, and reused.

  In addition to the developing roller recycling path 85Y, the squeeze roller developer recovery section 15Y sends the squeeze roller recycling path to the recycled developer storage section 81Y and the image carrier developer recovery section 17Y sends it to the recycled developer storage section 81Y. A latent image carrier recycling path or the like may be provided.

  Next, the waste developer collection device 90 will be described. The waste developer collecting device 90 is for discarding the developer that is not recycled. The developing roller waste developer collecting path 91Y as the second transport path, the developing roller waste developer collecting pump 92Y as the adjusting means, and the second It has a waste developer storage section 93 as a storage section.

  When the developer is discarded without being recycled, the developer scraped and collected by the developing roller cleaning blade 21Y is discarded by the developing roller waste developer collecting path 91Y via the developing roller waste developer collecting pump 92Y. Send to 93. Then, the waste developer is discarded from the waste developer storage unit 93.

  In addition to the developing roller recycling path 85Y, the squeeze roller developer recovery section 15Y sends the waste developer storage section 93 to the waste developer storage section 93 and the image carrier developer recovery section 17Y sends it to the waste developer storage section 93. A latent image carrier discarding path or the like may be provided.

  The image forming apparatus 1 of the present embodiment detects the charge amount of a liquid developer containing a developer solid content and a non-volatile liquid carrier, and the liquid developer on the collected developer carrier is detected according to the detection result. The flow rate of moving from the developing roller recycling path 85Y to the recycled developer storage unit 81Y and the flow rate of moving from the developing roller waste developer recovery path 91Y to the waste developer storage unit 93 are adjusted.

  A first embodiment of such recycle control will be described. In the first embodiment, the charge amount detection means for detecting the charge amount of the developer is constituted by a current detection means for detecting a current value when the developer is electrophoresed from the developing roller 20Y to the latent image carrier 10Y. is there. FIG. 6 shows a flowchart of the recycling control of this embodiment.

  First, in step 1, a solid image as shown in FIG. 7 is printed on the latent image carrier 10Y with a predetermined width equal to or greater than the nip width (ST1).

  Next, in step 2, a current value between the developing roller 20Y and the image carrier 10Y when the solid image is printed in step 1 is obtained by the current detection means (ST2).

  Here, the monitoring of the current value by the current detection means will be described. In the present embodiment, as shown in FIG. 8, the current of the power source that applies a bias to the developing roller 20Y is monitored. In the figure, 100Y is a current detection means, 101Y is an image carrier bias applying means, and 102Y is a developing roller bias applying means.

  An image carrier bias applying means 101Y is connected to the image carrier 10Y, and a bias is applied thereto. A developing roller bias applying unit 102Y is connected to the developing roller 20Y, and a larger bias than that of the image carrier 10Y is applied. Therefore, a current flows from the developing roller 20Y to the image carrier 10Y by the bias applied by the developing roller bias applying unit 102Y. The current detection means 100Y monitors the current of the power source that applies a bias to the developing roller 20Y at this time. The current detection unit 100Y is not limited to this method, and may be any device that detects the current flowing from the developing roller 20Y to the image carrier 10Y.

  Next, in step 3, the current value obtained by the current detection means 100Y in step 2 is compared with a plurality of predetermined values (ST3).

  Subsequently, in step 4, the recycling rate is determined based on the comparison result in step 3, and the amount of liquid developer sent to the recycling device 80 or the waste developer collecting device 90 is adjusted (ST4). This adjustment is performed by the pump speed of the developing roller recycle pump 86Y and the developing roller waste developer recovery pump 92Y.

  The adjustment of the amount of liquid developer sent to the recycling device 80 or the waste developer collection device 90 will be described. Table 1 is an example showing the relationship between the current value obtained by the current detection means 100Y and the recycling ratio.

  As shown in Table 1, when the current value is 20 μA or more, the recycling ratio is set to 100 wt%, and as shown by the arrow in FIG. 9, the collected liquid developer is supplied to the developing roller recycling path via the developing roller recycling pump 86Y. 85Y is sent to the recycled developer storage unit 81Y.

  When the current value is 17 μA, the recycling ratio is 92 wt%, the disposal ratio is 8 wt%, and as shown by the arrow in FIG. 10, the collected liquid developer is 92 wt% via the developing roller recycling pump 86Y. The recycle path 85Y is sent to the recycle developer storage section 81Y, and 8 wt% is sent to the waste developer storage section 93 via the development roller waste developer recovery pump 92Y through the development roller waste developer recovery path 91Y.

  When the current value is 14 μA, the recycling ratio is 75 wt% and the disposal ratio is 25 wt%. As shown in FIG. 10, the collected liquid developer is 75 wt% via the developing roller recycling pump 86Y. The recycle path 85Y is sent to the recycle developer storage section 81Y, and 25 wt% is sent to the waste developer storage section 93 via the development roller waste developer recovery pump 92Y through the development roller waste developer recovery path 91Y.

  Further, when the current value is 10 μA, the recycling ratio is 50 wt% and the disposal ratio is 50 wt%. As shown in FIG. 10, the collected liquid developer is 50 wt% through the developing roller recycling pump 86Y. The recycle path 85Y is sent to the recycle developer storage section 81Y, and 50 wt% is sent to the waste developer storage section 93 via the development roller waste developer recovery pump 92Y through the development roller waste developer recovery path 91Y.

  Further, when the current value is less than 8 μA, the discard ratio is set to 100 wt%, and the collected liquid developer is collected through the developing roller waste developer collecting pump 92Y as shown by the arrow in FIG. It is sent to the waste developer storage section 93 through the path 91Y.

  When the current value is 8 μA or more and less than 20 μA, the ratio may be obtained continuously based on the value of this embodiment or the like, or may be adjusted stepwise.

  A second embodiment of the recycling control will be described. In the second embodiment, the charge amount detecting means for detecting the charge amount of the developer is configured by detecting the density of the patch image printed on the intermediate transfer belt 40. FIG. 12 shows a flowchart of the recycling control of this embodiment.

  First, in step 11, a patch image is printed on the intermediate transfer belt 40 (ST11).

  Next, in step 12, the patch density when the patch image is printed in step 11 is obtained (ST12).

  Next, in step 13, the patch density obtained in step 12 is compared with a plurality of predetermined values (ST13).

  Subsequently, in step 14, the recycling rate is determined based on the comparison result in step 13, and the amount of liquid developer sent to the recycling device 80 or the waste developer collecting device 90 is adjusted (ST14). This adjustment is performed by the pump speed of the developing roller recycling pump 86Y and the developing roller waste developer recovery pump 92Y.

  The adjustment of the amount of liquid developer sent to the recycling device 80 or the waste developer collection device 90 will be described. Table 2 is an example showing the relationship between the patch concentration and the recycle ratio.

  As shown in Table 2, when the patch density is 1.32 or more, the recycle ratio is 100 wt%, and as shown by the arrow in FIG. 9, the collected liquid developer is supplied to the developing roller via the developing roller recycling pump 86Y. It is sent from the recycling path 85Y to the recycled developer storage unit 81Y.

  When the patch concentration is 1.30, the recycle ratio is 92 wt%, the discard ratio is 8 wt%, and as shown by the arrow in FIG. 10, the recovered liquid developer is 92 wt% via the developing roller recycle pump 86Y. It is sent from the developing roller recycling path 85Y to the recycled developer storage section 81Y, and 8 wt% is sent to the waste developer storage section 93 by the developing roller waste developer recovery path 91Y via the developing roller waste developer recovery pump 92Y. .

  When the patch concentration is 1.28, the recycle ratio is 75 wt% and the discard ratio is 25 wt%. As shown in FIG. 10, the collected liquid developer is 75 wt% via the developing roller recycle pump 86Y. It is sent from the developing roller recycling path 85Y to the recycled developer storage section 81Y, and 25 wt% is sent to the waste developer storage section 93 by the developing roller waste developer recovery path 91Y via the developing roller waste developer recovery pump 92Y. .

  Further, when the patch concentration is 1.25, the recycle ratio is 50 wt% and the discard ratio is 50 wt%. As shown in FIG. 10, the collected liquid developer is 50 wt% via the developing roller recycle pump 86Y. 50 wt% is sent from the developing roller recycling path 85Y to the recycled developer storage section 81Y and sent to the waste developer storage section 93 by the developing roller waste developer recovery path 91Y via the developing roller waste developer recovery pump 92Y. .

  When the patch density is less than 1.20, the discard ratio is set to 100 wt%, and as shown by the arrow in FIG. 11, the collected liquid developer is subjected to development roller waste development via the development roller waste developer collection pump 92Y. It is sent to the waste developer storage section 93 by the agent recovery path 91Y.

  When the patch density is 1.20 or more and less than 1.32, the ratio may be obtained continuously based on the value of this embodiment or the like, or may be adjusted stepwise.

  Although the recycling device 80 is provided for each of a plurality of colors, the waste developer collecting device 90 may be provided for each of a plurality of colors, or each color may be collected together.

  As described above, the image forming apparatus of the present embodiment includes a developing roller 20Y that carries a liquid developer containing developer solids and a liquid carrier, an image carrier 10Y that develops a latent image by the developing roller 20Y, An intermediate transfer belt 40 that forms an image by transferring an image on the latent image carrier 10Y, a secondary transfer unit 60 that transfers an image on the intermediate transfer belt 40 to a transfer material, and an image that is fixed to the transfer material. The fixing unit 70, the developing roller cleaning blade 21Y that collects the liquid developer on the developing roller 20Y, the recycled developer storage unit 81 that stores the liquid developer collected by the developing roller cleaning blade 21Y, and the waste developer storage unit 93. And the developing roller recycling in which the liquid developer collected by the developing roller cleaning blade 21Y moves to the recycled developer storage portion 81Y. A path 85Y, a developing roller waste developer collecting path 91Y through which the liquid developer collected by the developing roller cleaning blade 21Y moves to the waste developer storage section 93, a developing roller recycling path 85Y, and a developing roller waste developer collecting path 91Y. A developing roller recycle pump 86Y and a developing roller waste developer collecting pump 92Y for adjusting the flow rate of the liquid developer that moves, and a charge detection means for detecting the charge amount of the liquid developer, and the detection result of the charge amount detection means Accordingly, the developing roller recycling pump 86Y and the developing roller waste developer collecting pump 92Y are controlled, so that the charge amount of the developer can be adjusted with a simple configuration without adding a new charge amount adjusting mechanism.

  Further, since the current detection unit 100Y detects the charge amount from the current value when the developer is electrophoresed from the developing roller 20Y to the latent image carrier 10Y, the charge amount of the developer can be adjusted with a simple configuration. it can.

  Further, since the current detection unit 100Y detects a current that flows when a solid image is printed on the image carrier 10Y, it is easy to detect the current value of the developer solid content.

  Further, since the solid image is longer than the nip width between the developing roller 20Y and the image carrier 10Y, the detection of the current value is stable.

  Further, since the charge amount detection means detects the density of the image printed on the intermediate transfer belt 40, the charge amount of the developer can be adjusted with a simple configuration.

  The recycled developer storage unit 81 has a recycled developer storage unit that recycles the liquid developer recovered by the recovery means, and the waste developer storage unit 93 is a liquid developer recovered by the developing roller cleaning blade 21Y. Therefore, the ratio of the liquid developer to be recycled and the liquid developer to be discarded can be adjusted, and the amount of charge can be adjusted efficiently and accurately.

  Further, the developing roller 20, the latent image carrier 10, the developing roller cleaning blade 21, the recycled developer storage unit 81, the developing roller recycling path 85Y, the developing roller recycling pump 86Y, the developing roller waste developer collecting pump 92Y, and the charge amount detecting means. Are provided corresponding to a plurality of colors, respectively, so that the charge amount can be adjusted efficiently and accurately corresponding to the plurality of colors.

1 is a diagram illustrating an image forming apparatus according to an exemplary embodiment. FIG. 2 is a diagram illustrating a periphery of a developing unit of the image forming apparatus according to the present exemplary embodiment. It is a perspective view of a developer supply member. It is a figure explaining development by a development roller. It is a figure explaining the squeeze effect | action by a squeeze roller. It is a figure which shows the flowchart of 1st Embodiment of the recycle control of this embodiment. It is a figure which shows a solid image. It is a figure which shows an electric current detection means. It is a figure which shows the image forming apparatus in the case of all recycling. It is a figure which shows the image forming apparatus in the case of both recycling and disposal. It is a figure which shows the image forming apparatus in the case of all discard. It is a figure which shows the flowchart of 2nd Embodiment of the recycle control of this embodiment.

Explanation of symbols

  10Y, 10M, 10C, 10K ... latent image carrier, 11Y, 11M, 11C, 11K ... charging roller, 12Y, 12M, 12C, 12K ... exposure unit, 13Y ... squeeze roller, 14Y ... squeeze roller cleaning blade, 15Y ... squeeze Roller developer collecting unit, 16Y ... latent image carrier cleaning blade, 17Y ... latent image carrier developer collecting unit, 20Y, 20M, 20C, 20K ... developing roller (developer carrier), 21Y ... developing roller cleaning blade ( (Collecting means), 30Y, 30M, 30C, 30K ... developing unit, 31Y ... developer container, 32Y ... developer supply roller (developer supply member), 33Y ... regulator blade, 34Y ... stirring roller, 40 ... intermediate transfer belt ( Intermediate transfer member), 41 ... belt drive roller, 42 ... belt driven roller, 3 ... Intermediate transfer belt cleaning blade, 44 ... Intermediate transfer belt developer recovery unit, 50Y, 50M, 50C, 50K ... Primary transfer unit, 51Y ... Primary transfer backup roller, 60 ... Secondary transfer unit, 61 ... Secondary transfer roller 62 ... secondary transfer roller cleaning blade 63 ... secondary transfer roller developer collecting unit 70 ... fixing unit 71 ... heating roller 72 ... pressure roller 80Y ... recycling device 81Y ... recycled developer storage unit ( First storage unit), 82Y: Stirring roller, 83Y: High density developer tank, 84Y: High density developer pump, 85Y: Development roller recycling path (first transport path), 86Y: Development roller recycling pump, 87Y ... Carrier oil tank, 88Y ... open / close valve, 91Y ... developing roller recycling path (second transport path), 92Y ... current Roller recycle pump, 93Y ... waste developer storage portion (second reservoir portion), 100Y ... current detector (charge amount detecting means), 101Y ... image carrier bias application means, 102Y ... developer carrier bias application means

Claims (9)

  A developer carrying member carrying a liquid developer containing developer solids and a liquid carrier, an image carrying member for developing a latent image by the developer carrying member, and an image on the latent image carrying member are transferred. An intermediate transfer member that forms an image, a secondary transfer portion that transfers the image on the intermediate transfer member to a transfer material, a fixing portion that fixes the image on the transfer material, and liquid development on the developer carrier Recovery means for recovering the agent, first and second storage portions for storing the liquid developer recovered by the recovery means, and first of the liquid developer recovered by the recovery means moving to the first storage portion The flow rate of the liquid developer that moves in the transport path, the second transport path in which the liquid developer recovered by the recovery means moves to the second storage section, and the first transport path and the second transport path is adjusted. Adjustment means and charge level detection to detect the charge level of liquid developer And a stage, an image forming apparatus and controls the adjusting means in accordance with a detection result of the charge amount detection means.   The image forming apparatus according to claim 1, wherein the charge amount detection unit detects a charge amount from a current value when the developer is electrophoresed from the developer carrier to the latent image carrier.   The image forming apparatus according to claim 2, wherein the charge amount detection unit detects a current that flows when a solid image is printed on the image carrier.   The image forming apparatus according to claim 3, wherein the solid image is longer than a nip width between the developer carrier and the image carrier.   The image forming apparatus according to claim 1, wherein the charge amount detection unit detects a density of an image printed on the intermediate transfer member.   The first storage unit includes a recycled developer storage unit that recycles the liquid developer recovered by the recovery unit, and the second storage unit is a waste developer that discards the liquid developer recovered by the recovery unit. The image forming apparatus according to claim 1, further comprising a storage unit.   The developer carrier, the latent image carrier, the recovery unit, the first storage unit, the first transport path, the adjustment unit, and the charge amount detection unit are provided corresponding to a plurality of colors. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The charge amount of the liquid developer containing the developer solid content and the non-volatile liquid carrier is detected, and in accordance with the detection result, the first storage section from the first transport path of the liquid developer on the collected developer carrier An image forming method comprising adjusting a flow rate of moving to the second storage path and a flow rate of moving from the second transport path to the second storage unit.   The flow rate moving from the first transfer path to the first storage unit is a recycle flow rate, and the flow rate moving from the second transfer path to the second storage unit is a discarding flow rate. The image forming method according to claim 8.

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