JP5929284B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus.

  In the wet developing apparatus of Patent Document 1, a liquid developer is supplied to a developing roll by a supply roll immersed in a liquid developer in a developer tank, and the electrostatic developer formed on the photosensitive drum by the liquid developer in the developing roll. The latent image is developed into a toner image. Further, the wet developing apparatus of Patent Document 1 includes a partition plate that partitions the developer tank below the supply roll in the developer tank, and a gap is formed between the tip of the partition plate on the lower side surface over the entire axial length of the supply roll. Open and face each other.

  The developing device of Patent Document 2 has a rotatable first roll and a second roll for supplying a liquid developer to a developer supply roll, and the first roll and the second roll use the developer as a developer. By moving toward the supply roll, the bubbles existing around the developer supply roll are separated from the developer supply roll.

JP 2011-022453 A JP-A-2005-292639

  The present invention provides a developing device and an image forming apparatus capable of reducing bubbles in a liquid developer supplied to a developing rotator and suppressing uneven distribution of the liquid developer in a storage tank for storing the liquid developer. With the goal.

A developing device according to a first aspect of the present invention is configured to be capable of rotating with a storage tank for storing a liquid developer, a developing rotator that holds the liquid developer on an outer peripheral surface, and the rotation axis of the developing rotator being aligned. A rotation rotating part that is immersed in the liquid developer in the storage tank while rotating and supplies the liquid developer to the outer peripheral surface of the development rotating body; and the liquid developer in the storage tank is immersed in the liquid developer. A counter member disposed to face the supply rotator and to form a gap allowing the flow of the liquid developer at a position closer to the bottom of the storage tank than the surface facing the supply rotator; disposed downstream of the pre-Symbol counter member in the direction of rotation of the rotating body, through said gap, and means returning back to the upstream side of the opposing member of the liquid developer in the rotational direction.

  In the developing device according to a second aspect of the present invention, the return means is a liquid feed rotating body that is rotatably provided and feeds the liquid developer into the gap while rotating.

In the developing device according to a third aspect of the present invention, a gap between the supply rotating body and the facing member is narrowed toward the downstream side in the rotation direction.

In the developing device according to a fourth aspect of the present invention, the facing member is disposed below the lowest point of the outer peripheral surface of the supply rotator in the vertical direction.

The developing device according to a fifth aspect of the present invention is provided with a developer supply unit that supplies the liquid developer from the deepest portion of the storage tank into the storage tank.

An image forming apparatus according to a sixth aspect of the present invention is an image holding member that is rotatably provided and holds a latent image on an outer peripheral surface thereof, and supplies a liquid developer to the latent image of the image holding member to obtain a developer image. A developing device according to any one of claims 1 to 5, and a transfer unit that transfers the developer image of the image carrier to a recording medium.

  According to the first aspect of the present invention, the liquid development in the storage tank that reduces the bubbles in the liquid developer supplied to the developing rotator and stores the liquid developer, as compared with the configuration in which the opposing member and the return means are not provided. The uneven distribution of the agent can be suppressed.

  According to the second aspect of the present invention, the liquid developer can be returned to the upstream side with a simple configuration as compared with the configuration in which the liquid developer is returned to the upstream side using means other than rotation.

According to the third aspect of the present invention, bubbles in the liquid developer supplied to the developing rotator can be reduced compared to a configuration in which the gap between the supplying rotator and the opposing member does not change in the rotation direction of the supplying rotator .

According to the invention of claim 4 , bubbles in the liquid developer supplied to the developing rotator are compared with a configuration in which the opposing member is arranged above the lowest point of the outer peripheral surface of the supply rotator in the vertical direction. It can be further reduced .

According to the fifth aspect of the present invention , bubbles in the liquid developer held on the outer peripheral surface of the supply rotating body can be reduced as compared with a configuration in which a new liquid developer is supplied near the liquid developer surface .

According to the sixth aspect of the present invention, the unevenness of the developer image due to bubbles can be reduced as compared with the configuration in which the liquid developer is supplied to the developing rotator only by the supply rotator.

1 is a configuration diagram schematically illustrating an image forming apparatus according to a first embodiment of the present invention. 1 is a configuration diagram schematically illustrating a developing device according to a first embodiment of the present invention. FIG. 3 is a configuration diagram schematically showing a peripheral portion of a supply roll of the developing device according to the first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a state of a liquid developer when a supply roll of the developing device according to the first embodiment of the present invention is rotated. FIG. 5 is a schematic diagram illustrating a moving state of the liquid developer around the partition member and the auxiliary supply roll according to the first embodiment of the present invention. It is a block diagram which shows typically the supply roll periphery part of the developing device which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the state of a liquid developer when the supply roll of the developing device which concerns on 2nd Embodiment of this invention is rotated. It is explanatory drawing which shows the difference in the volume of the storage layer which concerns on 2nd Embodiment of this invention, and the storage layer of a comparative example.

(First embodiment)
An example of the developing device and the image forming apparatus according to the first embodiment of the present invention will be described.

(overall structure)
FIG. 1 shows an image forming apparatus 10 as an example of the first embodiment. The image forming apparatus 10 includes a photoconductor 12 as an example of an image holding body that is provided in a cylindrical shape so as to be rotatable and holds a latent image on an outer peripheral surface. Around the photoconductor 12, a charger 20, an exposure device 22, a developing device 100, a transfer device 30 as an example of a transfer unit, and a photoconductor cleaner 40 are arranged.

  The charger 20 is disposed on the lower side of the photoconductor 12 so as to be opposed to the outer peripheral surface of the photoconductor 12 with a space therebetween. As an example, the charger 20 is a scorotron charger. The charger 20 charges the surface (outer peripheral surface) of the photoreceptor 12 by corona discharge.

  The exposure device 22 is provided on the downstream side of the charger 20 in the rotation direction of the photoconductor 12, and is an LED exposure device as an example. Then, the exposure device 22 exposes the outer peripheral surface of the photoconductor 12 charged by the charger 20 based on the image information, and forms a latent image on the outer peripheral surface of the photoconductor 12. The exposure device 22 may be an exposure device other than the LED exposure device. For example, an exposure apparatus that performs exposure with a laser beam may be used.

  The developing device 100 is provided on the downstream side of the exposure device 22 in the rotation direction of the photoconductor 12, and a latent image formed on the photoconductor 12 with a liquid developer G in which toner (particles) is dispersed in a carrier liquid. Is developed (visualized) to form a toner image (developer image) on the outer peripheral surface of the photoreceptor 12. Details of the developing device 100 and the liquid developer G will be described later.

  The transfer device 30 is provided on the downstream side of the developing device 100 in the rotation direction of the photoconductor 12. Further, the transfer device 30 is transferred to the outer peripheral surface of the cylindrical intermediate transfer member 32 onto which the toner image formed on the outer peripheral surface of the photosensitive member 12 is transferred, the intermediate transfer member cleaner 50, and the intermediate transfer member 32. An intermediate transfer type apparatus having a transfer roll 34 for transferring a toner image onto a recording paper P as an example of a recording medium. The toner image is transferred onto the recording paper P by the transfer roll 34 via an intermediate transfer body 32. .

  The transfer device 30 may have a configuration other than the above configuration. For example, a configuration including a belt-like intermediate transfer member may be used, or the toner image may be directly transferred from the photosensitive member 12 to the recording paper P by the transfer roller 34 without the intermediate transfer member and the intermediate transfer member cleaner. A direct transfer system may be used.

  The photoconductor cleaner 40 includes a first waste toner tank 42, a cleaning roller 44 that contacts the outer peripheral surface of the photoconductor 12 upstream of the charger 20 in the rotation direction of the photoconductor 12, and a cleaning blade 46 made of urethane rubber. , 48. The cleaning blades 46 and 48 are in contact with the photoreceptor 12 and the cleaning roll 44, respectively, and remove the liquid developer G remaining on the outer peripheral surface of the photoreceptor 12 after the transfer. The removed liquid developer G is collected in the first waste toner tank 42.

  The intermediate transfer body cleaner 50 includes a second waste toner tank 52, a cleaning roll 54 that contacts the outer peripheral surface of the intermediate transfer body 32, and urethane rubber cleaning blades 56 and 58. The cleaning blades 56 and 58 contact the intermediate transfer member 32 and the cleaning roll 54, respectively, and remove the liquid developer G. The removed liquid developer G is collected in the second waste toner tank 52. The liquid developer G collected in the second waste toner tank 52 is sent to the first waste toner tank 42 via the pipe 59.

  The cleaning roll 44 for the photoreceptor 12 and the cleaning roll 54 for the intermediate transfer member are, as an example, oil resistant such as NBR (acrylonitrile butadiene rubber) or ECO (epichlorohydrin rubber) on the surface of a SUS core. It is made into the roll member which coat | covered a certain rubber | gum, and the layer thickness of rubber | gum shall be 5-20 mm as an example. Further, the cleaning roll for the intermediate transfer member 32 may be made of metal such as aluminum, iron, SUS steel. At this time, smoothness and wear resistance can be improved by plating the roll surface.

  Further, the image forming apparatus 10 includes a storage unit 60 in which the recording paper P is stored, and the recording paper P is transported along the transport path K. Further, the image forming apparatus 10 includes a fixing device 70 that fixes the toner image on the recording paper P onto which the toner image is transferred. As an example of the fixing method in the fixing device 70, contact-type thermal fixing using a fixing roll 72 and a pressure roll 74 is used. However, contact-type thermal fixing using a fixing roll or a belt may be used. Non-contact heat fixing using a flash lamp or the like may be used.

(Image formation process)
Next, an image forming process of the image forming apparatus 10 will be described.

  Each roll is configured to be rotated by a driving device (not shown) in the direction indicated by the arrow or to be rotated by a driven rotation.

  As shown in FIG. 1, the surface of the photoreceptor 12 is charged by the charger 20, and a latent image based on the image information is formed by the exposure device 22. The latent image on the outer peripheral surface of the photoconductor 12 is developed by the developing device 100, and a toner image is formed on the surface of the photoconductor 12.

  Subsequently, the toner image formed on the photosensitive member 12 is subjected to a potential difference between the grounded photosensitive member 12 and the intermediate transfer member 32 by applying a bias voltage to a core (not shown) of the intermediate transfer member 32. Primary transfer is performed on the outer peripheral surface of the intermediate transfer body 32. The primarily transferred toner image is secondarily transferred to the recording paper P by the potential difference between the bias voltage applied to the intermediate transfer body 32 and the bias voltage applied to the transfer roll 34.

  Subsequently, the recording paper P to which the toner image is transferred is conveyed to the fixing device 70, and the toner image is fixed on the recording paper P. Then, the recording paper P on which the toner image is fixed is discharged to a discharge unit 76 provided at the end of the conveyance path K in the image forming apparatus 10.

  Here, the liquid developer G remaining on the photosensitive member 12 without being primarily transferred to the intermediate transfer member 32 is removed by the photosensitive member cleaner 40. Further, the liquid developer G remaining on the intermediate transfer body 32 without being secondarily transferred onto the recording paper P is removed by the intermediate transfer body cleaner 50.

  It should be noted that the toner in the remaining liquid developer G mainly adheres to the cleaning rolls 44 and 54 by applying a bias voltage to the cores of the cleaning roll 44 for the photoconductor and the cleaning roll 54 for intermediate transfer. Removed. Then, after the remaining toner in the liquid developer G is removed, the carrier liquid is removed by the photoconductor cleaning roll 44 and the intermediate transfer cleaning roll 54.

(Main part configuration)
Next, the developing device 100 will be described.

  As illustrated in FIG. 2, the developing device 100 includes a storage tank 102 that stores the liquid developer G, a developing roll 104 that is an example of a developing rotating body that holds the liquid developer G on the outer peripheral surface, and a liquid developer G. Supply roll (anilox roll) 106 as an example of a supply rotator that supplies the outer peripheral surface of the development roll 104, and a partition as an example of a facing member that is immersed in the liquid developer G in the storage tank 102 and faces the supply roll 106. A member 110, a return means for immersing the liquid developer G in the storage tank 102 and returning the liquid developer G to the upstream side of the partition member 108 in the rotation direction, and an auxiliary roll 112 as an example of a liquid feeding rotating body. doing.

  Further, the developing device 100 includes a regulation blade 108 that regulates the amount of liquid developer on the outer peripheral surface of the supply roll 106, and a developer supply unit 120 that supplies the liquid developer G into the storage tank 102. .

  In the liquid developer G, toner (particles) is dispersed in a carrier liquid. As the carrier liquid, for example, an insulating liquid such as vegetable oil, liquid paraffin oil, or silicone oil is used. For example, the liquid developer G has an average particle size of toner (particles) of 0.5 μm or more and 5 μm or less, and the toner (particles) is dispersed in the carrier liquid at a concentration of 15 wt% or more and 35 wt% or less. ing. Note that a charge control agent and a dispersant may be added to the liquid developer G. The liquid developer G (carrier liquid) decreases in viscosity as the temperature increases, and increases in viscosity as the temperature decreases.

  The storage tank 102 is a container formed in an arc shape in which a rotation axis direction of the supply roll 106 (hereinafter referred to as an axial direction) is a longitudinal direction and a cross section intersecting with the longitudinal direction is opened upward. And the storage tank 102 has the curved wall 102A and the curved wall 102B which are arrange | positioned on the same circular arc as an example seeing in a longitudinal direction.

  The curved wall 102 </ b> A is a wall curved in an arc shape at a position below the rotation center O of the supply roll 106 (lower right side in the drawing) and facing the outer peripheral surface of the supply roll 106. In addition, the curved wall 102 </ b> A is arranged along the circumferential direction of the supply roll 106 so that the distance from the outer peripheral surface of the supply roll 106 is the same.

  The curved wall 102 </ b> B is a wall that is curved in an arc shape at a position below the rotation center O of the supply roll 106 (lower left side in the drawing) and facing the outer peripheral surface of the supply roll 106. The curved wall 102 </ b> B is arranged along the circumferential direction of the supply roll 106 so that the interval between the curved wall 102 </ b> B and the outer peripheral surface of the supply roll 106 is approximately the same. The curved walls 102 </ b> A and 102 </ b> B are arranged symmetrically with respect to the rotation center O of the supply roll 106. Further, the liquid developer G is stored in the storage tank 102.

  Further, as an example, the storage tank 102 is provided with a liquid level detection sensor (not shown) that detects the remaining amount of the liquid developer G. When the liquid developer G stored in the storage tank 102 decreases and becomes insufficient, a new liquid developer G is supplied (supplemented) to the storage tank 102 by the developer supply unit 120.

For example, the developing roll 104 is provided with an elastic layer 104B having a semiconductivity of 1 × 10 ⁵ Ω · cm to 1 × 10 ¹⁰ Ω · cm on the surface of a metal cylindrical core roll 104A. It has been. A bias voltage is applied to the metal core roll 104A.

  Further, in the developing roll 104, the supply roll 106 comes into contact with the elastic layer 104B, and the developer layer GT of the liquid developer G is formed on the developing roll 104 in the layer forming portion M that is the contact portion. Further, the elastic layer 104B of the developing roll 104 is in contact with the photoreceptor 12 to form a developing nip portion N (developing portion), and the liquid developer G of the developer layer GT is in the developing nip portion N so that the photoreceptor 12 Metastasize up. Then, on the downstream side in the rotation direction of the developing roll 104 with respect to the developing nip portion N, the liquid developer (not shown) that has not been transferred onto the photoreceptor 12 remains on the developing roll 104. In the layer forming section M, the supply roll 106 and the developing roll 104 are moved (rotated) in the same direction, and in the developing nip section N, the developing roll 104 and the photoconductor 12 are moved (rotated) in the same direction.

  A charger 105 is provided between the layer forming portion M and the developing nip portion N around the developing roll 104 (in a range facing the outer peripheral surface). The charger 105 charges the surface of the developer layer GT between the layer forming portion M and the developing nip portion N. In other words, the charger 105 charges the developer layer GT on the upstream side in the rotation direction of the developing roll 104 with respect to the photoreceptor 12. The charger 105 charges the developer layer GT so as to have the same polarity as the polarity of the toner constituting the developer layer GT (liquid developer G). The charger 105 is, for example, a corotron charger that charges the developer layer GT by corona discharge.

  The supply roll 106 is rotatably provided so as to be aligned with the developing roll 104 in the axial direction, the lower end portion is immersed in the liquid developer G in the storage tank 102, and the portion not immersed in the liquid developer G is connected to the developing roll 104. In contact. The supply roll 106 is rotated while a part (lower end portion) is immersed in the liquid developer G in the storage tank 102, thereby holding the liquid developer G on the outer peripheral surface and supplying the liquid developer G to the outer peripheral surface of the developing roll 104. It is like that.

  Further, as an example, an oblique groove pattern engraving groove is formed on the outer peripheral surface (surface) of the supply roll 106. As the shape of the engraving groove on the surface of the supply roll 106, a pyramid pattern, a lattice pattern, a honeycomb pattern, or the like may be used in addition to the hatched pattern.

  For example, the regulation blade 108 is configured by a plate-like member having the axial direction of the supply roll 106 as a longitudinal direction, and is disposed so as to face the outer peripheral surface of the supply roll 106, and the end portion in the short direction is the supply roll. 106 is in contact with the outer peripheral surface (upper left side with respect to the center of rotation O shown). Thereby, the regulation blade 108 regulates the amount of the liquid developer G on the outer peripheral surface of the supply roll 106 outside the storage tank 102. If the amount of the liquid developer G held on the supply roll 106 can be within the set amount, the regulating blade 108 has a gap between the end in the short direction and the outer peripheral surface of the supply roll 106. May be arranged.

  As shown in FIG. 3, as an example, the partition member 110 is configured by a trapezoidal member whose cross-sectional shape intersects the longitudinal direction with the axial direction of the supply roll 106 as the longitudinal direction. Specifically, the partition member 110 includes a lower surface 110A arranged substantially horizontally as viewed in the longitudinal direction, a right side surface 110B and a left side surface 110C standing upright at both left and right ends of the lower surface 110A, and a left side from the upper end of the right side surface 110B. And an inclined surface 110D inclined toward the upper end of the surface 110C. The both end portions in the longitudinal direction of the partition member 110 are located outside the both end portions in the axial direction of the supply roll 106.

  Further, the partition member 110 has a gap 111 that allows the flow of the liquid developer G closer to the bottom of the storage tank 102 than the surface facing the supply roll 106. That is, in the partition member 110, a gap 111 is formed between the lower surface 110 </ b> A and the inner wall surface (bottom) of the storage layer 102, and the liquid developer G can flow through the gap 111.

  Further, the partition member 110 is located at a higher position in the vertical direction (vertical direction) than the point B, with the upper end of the right side surface 110B as the point B and the upper end of the left side surface 110C as the point C in the cross section viewed in the longitudinal direction. Are inclined obliquely upward from point B to point C. The distance between the point C and the outer peripheral surface of the supply roll 106 is narrower than the distance between the point B and the outer peripheral surface of the supply roll 106. That is, the distance between the outer peripheral surface of the supply roll 106 and the inclined surface 110 </ b> D of the partition member 110 is narrower toward the downstream side in the rotation direction of the supply roll 106.

  Here, when the lowest point of the outer peripheral surface of the supply roll 106 in the vertical direction is a point A, the points B and C of the partition member 110 are arranged below the point A. That is, the partition member 110 is disposed below the lowest point of the outer peripheral surface of the supply roll 106 in the vertical direction. Further, when a straight line connecting the rotation center O of the supply roll 106 and the point A is indicated by a broken line L, the right side surface 110B of the partition member 110 is, as an example, the left side of the broken line L (downstream in the rotation direction of the supply roll 106). It is shifted and arranged. The right side surface 110B of the partition member 110 may be located on the broken line L.

  On the other hand, the auxiliary roll 112 is a columnar member that is axially aligned with the supply roll 106 and is rotatably provided by a driving means (not shown). For example, the diameter of the auxiliary roll 112 is longer than the length corresponding to the height of the left side surface 110 </ b> C of the partition member 110.

  Further, the auxiliary roll 112 is spaced from the outer peripheral surface of the supply roll 106 at a position downstream of the partition member 110 in the rotation direction of the supply roll 106 and opposed to the outer peripheral surface of the supply roll 106, and is supplied. The supply roll 106 moves (rotates) in the same direction as the movement (rotation) direction of the supply roll 106 within a range facing the outer peripheral surface of the roll 106. Further, a gap 113 is formed between the auxiliary roll 112 and the bottom of the storage tank 102.

  As shown in FIG. 2, the developer supply unit 120 is provided in a storage tank 122 that stores the liquid developer G therein, a supply path 124 that connects the storage tank 122 and the storage tank 102, and the supply path 124. A storage tank 122 and a pump 126 for supplying the liquid developer G in the supply path 124 into the storage tank 102. Further, between the storage tank 122 and the pump 126 in the replenishment path 124, a deaeration unit 128 that removes bubbles in the liquid developer G and a toner concentration that detects the concentration of toner (particles) in the liquid developer G. Sensor 132 is provided.

  As an example, the storage tank 122 is configured such that toner (particles) and carrier liquid are supplied by different supply units, and the liquid developer G is generated by stirring and stores the liquid developer G therein. ing.

  As an example, the supply path 124 is configured by a pipe, and one end is connected to the storage tank 122 and the other end is connected to the deepest portion of the storage tank 102.

  As an example, the pump 126 operates based on information from a liquid level detection sensor (not shown) that detects the height of the liquid level of the liquid developer G stored in the storage tank 102. It has become. That is, when the shortage information of the liquid developer G in the storage tank 102 is input from the liquid level detection sensor, the operation is started, and the shortage information of the liquid developer G in the storage tank 102 is not input from the liquid level detection sensor. If so, stop working.

  For example, the deaeration unit 128 is configured to flow the liquid developer G into one space partitioned by a gas-liquid separation membrane (not shown) and depressurize the other space to remove bubbles in the liquid developer G. It has become. Further, the deaeration unit 128 is provided on the upstream side (the side closer to the storage tank 122) than the toner concentration sensor 132 in the direction in which the liquid developer G flows.

  For example, the toner concentration sensor 132 includes a light emitting element and a light receiving element (not shown), and detects the toner concentration based on the amount of light emitted from the light emitting element, transmitted through the liquid developer G, and received by the light receiving element. It is supposed to be. That is, the greater the ratio of light being blocked, the higher the toner density. When the toner concentration detected by the toner concentration sensor 132 is higher than the reference concentration, the carrier liquid is supplied to the storage tank 122, and when it is lower than the reference concentration, toner (including a part of the carrier liquid) is supplied. The toner concentration of the liquid developer G is adjusted.

(Function)
Next, the operation of the first embodiment will be described.

  As shown in FIG. 2, in the image forming apparatus 10, a control unit (not shown) operates the pump 126 to supply (supplement) the liquid developer G from the storage tank 122 to the storage tank 102. The liquid developer G is deaerated by the deaeration unit 128, and then the toner concentration is detected by the toner concentration sensor 132 and supplied to the storage tank 102. As a result, the lower portion of the supply roll 106 is immersed in the liquid developer G in the storage tank 102.

  Subsequently, as shown in FIG. 4, the supply roll 106 rotates in accordance with the start of the image forming operation, and the liquid developer G is held on the outer peripheral surface of the supply roll 106. At this time, a part of the bubbles B existing in the vicinity of the upstream liquid surface in the rotation direction of the supply roll 106 in the storage tank 102 is conveyed downstream together with the liquid developer G as the supply roll 106 rotates. A part of the liquid developer G held on the outer peripheral surface of the supply roll 106 enters the gap between the outer peripheral surface of the supply roll 106 and the partition member 110.

  Here, as shown in FIG. 5, the gap 117 between the outer peripheral surface of the supply roll 106 and the inclined surface 110 </ b> D of the partition member 110 is narrowed toward the downstream side in the rotation direction of the supply roll 106. For this reason, the liquid developer G that has entered the gap 117 (indicated by the arrow Q indicates the moving state) is pressurized, and the bubbles B adhering to the outer peripheral surface of the supply roll 106 are removed, so the developing roll 104 (see FIG. 2). Bubbles B in the liquid developer G to be supplied to decrease.

  Subsequently, the auxiliary roll 112 feeds the liquid developer G into the gap 111 between the partition member 110 and the bottom of the storage tank 102 while rotating. A part of the liquid developer G conveyed by the supply roll 106 to the downstream side of the partition member 110 moves in the arrow S direction, and passes through the gap 111 between the partition member 110 and the bottom of the storage tank 102, and the supply roll. 106 is returned to the upstream side of the partition member 110 in the rotational direction.

  When the auxiliary roll 112 is not provided, the liquid developer G moves along with the rotation of the supply roll 106, so that the liquid level of the liquid developer G stored upstream of the partition member 110 is The liquid level of the liquid developer G stored on the downstream side of the partition member 110 becomes lower than the liquid level.

  In this embodiment, the liquid level of the liquid developer G stored on the upstream side of the partition member 110 and the liquid developer G stored on the downstream side of the partition member 110 by the auxiliary roll 112. The difference from the height of the liquid level is reduced, and the uneven distribution of the liquid developer G in the storage tank 102 is suppressed. Since the liquid developer G is returned to the upstream side only by the rotation of the auxiliary roll 112, compared to a configuration that does not use a rotating means (for example, a configuration in which the liquid developer G is returned to the upstream side using a sliding member). Simple configuration.

  Subsequently, a part of the liquid developer G held on the outer peripheral surface of the supply roll 106 passes through the gap between the supply roll 106 and the regulating blade 108 and is supplied to the development roll 104 (see FIG. 2). Then, the remaining liquid developer G is scraped off to the storage tank 102 side by the regulating blade 108.

  Here, in the developing device 100, since the new liquid developer G is supplied from the deepest part of the storage tank 102, the new liquid developer G is not supplied near the liquid surface of the liquid developer G. As a result, the liquid developer G is supplied not near the liquid surface where the bubbles B are relatively large but near the lowest point of the supply roll 106 where the bubbles B are small, so that the bubbles B are contained in the supplied liquid developer G. It becomes difficult to mix, and the bubbles B in the liquid developer G held on the outer peripheral surface of the supply roll 106 are reduced.

  Further, in the developing device 100, the partition member 110 is disposed below the lowest point (point A in FIG. 3) of the outer peripheral surface of the supply roll 106 in the vertical direction. For this reason, compared to the configuration in which the partition member 110 is disposed above the lowest point of the outer peripheral surface of the supply roll 106, the pressure acts on the liquid developer G in a place where the bubbles B are few, so the developing roll 104 ( The bubbles B in the liquid developer G supplied to (see FIG. 2) are further reduced.

  Furthermore, in the developing device 100, the partition member 110 is disposed below the lowest point of the outer peripheral surface of the supply roll 106 in the vertical direction, so that the liquid level of the liquid developer G is lowered. In addition, the operation of the partition member 110 and the auxiliary roll 112 is maintained.

  In addition, in the developing device 100, since the bubbles B in the liquid developer G held on the outer peripheral surface of the supply roll 106 are reduced, uneven formation of the layer of the liquid developer G on the outer peripheral surface of the supply roll 106 occurs. This suppresses the unevenness of the developer image formed on the outer peripheral surface of the photoreceptor 12 (see FIG. 1).

(Second Embodiment)
Next, an example of a developing device and an image forming apparatus according to the second embodiment of the present invention will be described. Note that the same reference numerals as those in the first embodiment are given to the same members and parts as those in the first embodiment described above, and the description thereof is omitted. In this specification, “second embodiment” is read as “reference example”.

  FIG. 6 shows a developing device 140 according to the second embodiment. The developing device 140 includes a storage layer 142, an auxiliary roll 146 as an example of a rotating member, a blocking wall 148, instead of the storage tank 102 (see FIG. 2) in the developing device 100 (see FIG. 2) of the first embodiment. In addition, the overflow portion 151 is provided, and other configurations are the same as those of the developing device 100 including the developing roll 104 (not shown in FIGS. 6 to 8). The auxiliary roll 146 is also an example of a return means, a facing member, and a liquid feeding rotating body. The overflow portion 151 includes a curved wall 144B, which will be described later, and a receiving portion 150 that receives the liquid developer G overflowing from the curved wall 144B.

  As an example, the storage tank 142 is a container having an axial direction of the supply roll 106 as a longitudinal direction and a cross section intersecting with the longitudinal direction opened upward. Specifically, the storage tank 142 is formed continuously from the first curved wall 143 that is curved along the outer peripheral surface of the auxiliary roll 146 and the upper end of the first curved wall 143 when viewed in the longitudinal direction. And a second curved wall 144 that curves along the outer peripheral surface.

  The second curved wall 144 has a curved wall 144A extending obliquely upward from the upper end of one side (the right side in the figure) of the first curved wall 143 and the other side (the left side in the figure) of the first curved wall 143 when viewed in the longitudinal direction. ) And the curved wall 144B extending obliquely upward from the upper end.

  The first curved wall 143 has a U-shaped cross section when viewed in the longitudinal direction, and opens toward the outer peripheral surface of the supply roll 106 on the lower side of the rotation center O of the supply roll 106, and the bottom (the rotation center of the auxiliary roll 146). One end of the supply path 124 is connected to the lower side of the OA.

  The curved wall 144A is a wall that is curved in an arc shape from one upper end of the first curved wall 143 to the upper right in the figure. The curved wall 144 </ b> A is arranged along the circumferential direction of the supply roll 106 so that the interval between the curved wall 144 </ b> A and the outer peripheral surface of the supply roll 106 is approximately the same.

  The curved wall 144B is a wall that is curved in an arc shape from the other upper end of the first curved wall 143 to the upper left in the figure (toward the receiving portion 150). Further, the curved wall 144 </ b> B is disposed so that the distance between the curved wall 144 </ b> B and the outer peripheral surface of the supply roll 106 is approximately the same along the circumferential direction of the supply roll 106. Note that when the storage tank 142 is viewed in the longitudinal direction, the upper end of the curved wall 144A is higher than the upper end of the curved wall 144B. The liquid developer G is stored in the storage tank 142.

  Furthermore, the storage tank 142 is provided with the above-described liquid level detection sensor (not shown) that detects the remaining amount of the liquid developer G as an example. When the liquid developer G stored in the storage tank 142 decreases and becomes insufficient, a new liquid developer G is supplied (supplied) to the storage tank 142 by the developer supply unit 120 (see FIG. 2).

  In addition, the storage tank 142 is provided with a receiving portion 150 outside the curved wall 144B, and the upper end of the receiving portion 150 (the upper right end in the figure) is attached to the lower surface of the curved wall 144B.

  Further, a blocking wall 148 is provided from the inside to the outside of the liquid developer G on the supply roll 106 side of the liquid developer G dropping position. The blocking member 148 faces the outer peripheral surface of the supply roll 106. Further, the tip end portion of the regulating blade 108 is in contact with the outer peripheral surface of the supply roll 106.

  The auxiliary roll 146 aligns the rotation axis direction with the supply roll 106 between the bottom of the storage tank 142 (first curved wall 143) and the outer peripheral face of the supply roll 106, and is spaced from the outer peripheral face of the supply roll 106. The cylindrical member is rotatably provided so as to be rotated in the same direction as the supply roll 106 by a driving means (not shown) at a position facing each other. The auxiliary roll 146 is housed in the first curved wall 143 with a gap from the inner wall of the first curved wall 143. The auxiliary roll 146 is disposed below the lowest point of the outer peripheral surface of the supply roll 106 in the vertical direction.

  As an example, the blocking wall 148 is formed of a member having an axial direction of the supply roll 106 as a longitudinal direction and a cross-sectional shape intersecting the longitudinal direction having an arc shape. Both end portions in the longitudinal direction of the blocking wall 148 are positioned outside both end portions in the axial direction of the supply roll 106. Further, the blocking wall 148 is viewed from a cross section intersecting with the longitudinal direction, and is lower than the drop position on the liquid level of the liquid developer G in the storage tank 142 where the liquid developer G scraped off by the regulating blade 108 falls. The liquid developer G is provided from the inside to the outside at a position on the supply roll 106 side. The blocking wall 148 is arranged along the circumferential direction of the supply roll 106 so that the distance from the outer peripheral surface of the supply roll 106 is approximately the same.

  As an example, the position of the liquid developer G falling in the storage tank 142 on the liquid surface falls when the supply roll 106 rotates at a preset rotational speed, and the liquid developer drops from the tip of the regulating blade 108. The arrival position of the agent G on the liquid surface is confirmed by experiments, and the position of the obtained arrival position is set closest to the outer peripheral surface of the supply roll 106.

  The receiving part 150 is provided outside the curved wall 144B. In addition, the receiving portion 150 has a longitudinal direction that is the axial direction of the supply roll 106, and a cross section that intersects the longitudinal direction is configured by a substantially L-shaped wall. And the side wall of the receiving part 150 standing upright in the vertical direction extends upward so that the upper end is above the position of the upper end of the curved wall 144B. Thereby, the liquid developer G overflowing from the upper end of the curved wall 144B is accommodated in the receiving portion 150. The receiving unit 150 and the storage tank 122 (see FIG. 2) are connected by a pipe (not shown), and the liquid developer G in the receiving unit 150 flows through the pipe by its own weight and is collected in the storage tank 122. It has come to be.

(Function)
Next, the operation of the second embodiment will be described.

  As shown in FIG. 6, in the developing device 140, a control unit (not shown) operates the pump 126 (see FIG. 2) to supply the liquid developer G from the storage tank 122 (see FIG. 2) to the storage tank 142 ( Supply) is performed. Thereby, in the storage tank 142, the liquid level of the liquid developer G reaches the upper end of the curved wall 144B.

  Subsequently, as shown in FIG. 7, the supply roll 106 and the auxiliary roll 144 rotate in accordance with the start of the image forming operation. Then, between the supply roll 106 and the auxiliary roll 144, the liquid developer G that has flowed in the direction of the arrow Q is pushed into the narrow channel and pressurized, and the bubbles B adhering to the outer peripheral surface of the supply roll 106 are removed. Therefore, the bubbles B in the liquid developer G supplied to the developing roll 104 (see FIG. 2) are reduced.

  Here, in the developing device 140, the auxiliary roll 146 is disposed below the lowest point (point A in FIG. 3) of the outer peripheral surface of the supply roll 106 in the vertical direction. For this reason, compared with the configuration in which the auxiliary roll 146 is disposed above the lowest point of the outer peripheral surface of the supply roll 106, the pressure acts on the liquid developer G in a place where the bubbles B are few, so the developing roll 104 ( The bubbles B in the liquid developer G supplied to (see FIG. 2) are further reduced.

  In the developing device 140, since the new liquid developer G is supplied from the deepest part of the storage tank 142, the new liquid developer G is not supplied near the liquid surface of the liquid developer G. As a result, the liquid developer G is supplied not near the liquid surface where the bubbles B are relatively large but near the lowest point of the supply roll 106 where the bubbles B are small, so that bubbles are contained in the supplied liquid developer G. B becomes difficult to mix, and the bubbles B in the liquid developer G held on the outer peripheral surface of the supply roll 106 are reduced.

  Further, in the developing device 140, the auxiliary roll 146 is disposed below the lowest point of the outer peripheral surface of the supply roll 106 in the vertical direction, so that the liquid level of the liquid developer G is lowered. However, the action of the auxiliary roll 146 is maintained.

  Subsequently, the auxiliary roll 146 feeds the liquid developer G between the auxiliary roll 146 and the bottom of the storage tank 142 while rotating. That is, a part of the liquid developer G conveyed by the supply roll 106 to the downstream side of the auxiliary roll 146 moves in the arrow S direction, and the bottom of the auxiliary roll 146 and the storage tank 142 (the bottom of the first curved wall 143). ) To the upstream side of the auxiliary roll 146 in the rotation direction of the supply roll 106.

  Thereby, the difference between the height of the liquid developer G stored upstream of the auxiliary roll 146 and the height of the liquid developer G stored downstream of the auxiliary roll 146. And the uneven distribution of the liquid developer G in the storage tank 142 is suppressed. Since the liquid developer G is pressurized and transported upstream by one auxiliary roll 146, the developing device is downsized.

  Subsequently, a part of the liquid developer G held on the outer peripheral surface of the supply roll 106 passes through the regulation blade 108 and is supplied to the development roll 104 (see FIG. 2), and the rest is stored in the storage tank 142 by the regulation blade 108. Scratched to the side.

  Subsequently, in the storage tank 142, due to the drop of the liquid developer G scraped off by the regulating blade 108, bubbles B and pulsations (waves) of the liquid level are generated at the drop position. In FIG. 7, the pulsation of the liquid level is not shown.

  Here, in the developing device 140, the movement of the bubble B and the pulsation of the liquid level generated at the dropping position are blocked by the blocking wall 148 before reaching the supply roll 106. Thereby, bubbles B contained in the liquid developer G on the outer peripheral surface of the supply roll 106 are reduced. Since the pulsation of the liquid surface is suppressed as the bubbles B are reduced, uneven formation of the liquid developer G layer on the outer peripheral surface of the supply roll 106 is suppressed, and the photoreceptor 12 (see FIG. 1). The unevenness of the developer image formed on the outer peripheral surface of the toner is reduced.

  Further, in the developing device 140, the liquid level of the liquid developer G is raised by supplying a new liquid developer G from the developer supply unit 120 (see FIG. 2). Then, the drop position and the surface layer portion of the liquid developer G in the vicinity of the drop position overflow the upper end of the curved wall 144B and overflow to the receiving portion 150. Here, since the bubbles B generated at the dropping position exist in the surface layer portion, the bubbles B are removed together with the liquid developer G overflowing to the receiving portion 150. Thereby, bubbles B on the liquid surface on the side where the supply roll 106 comes out of the liquid surface are reduced.

  Further, as illustrated in FIG. 8, the developing device 140 includes a storage tank 142 having a first curved wall 143 along the outer peripheral surface of the auxiliary roll 146 and a second curved wall 144 along the outer peripheral surface of the supply roll 106. It is configured. For this reason, the volume of the storage tank 142 is reduced by the volume V indicated by the diagonal lines compared to the case where the storage tank is configured by one curved wall 200 (illustrated by a two-dot chain line) as a comparative example. Further, since the volume of the storage tank 142 is reduced, the amount of carrier liquid and the amount of toner charged into the storage tank 122 (see FIG. 2) is reduced, so that it is easy to suppress the occurrence of uneven toner particle concentration in the liquid developer G. .

  In addition, this invention is not limited to said embodiment.

  The charger 105 is a corotron charger, but may be a scorotron charger. Furthermore, you may use well-known chargers (charging means), such as an electrode needle and a saw-tooth charger.

  Further, the image forming apparatus 10 is not limited to one that forms an image on the recording paper P with the liquid developer G of one color, but may be one that forms an image on the recording paper P with the liquid developer G of a plurality of colors. For example, an image forming apparatus having a configuration in which a plurality of developing devices 100 or developing devices 140 are arranged may be used.

  Further, the toner concentration sensor 132 is not limited to the optical type, and may be one that measures the toner concentration in the liquid developer G by attenuation of ultrasonic waves, for example.

  Further, the partition member 110 may have a triangular cross-sectional shape.

  Further, the returning means is not limited to the rotating body, and any means may be used as long as it moves the liquid developer G to the upstream side. As an example, the liquid developer G can be moved by moving a slide member that can slide in the horizontal direction. May be sent from the downstream side to the upstream side.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photosensitive body (an example of an image holding body)
30 Transfer device (an example of transfer means)
DESCRIPTION OF SYMBOLS 100 Developing apparatus 102 Storage tank 104 Developing roll (an example of a developing rotating body)
106 Supply roll (an example of a supply rotator)
110 Partition member (example of opposing member)
112 Auxiliary roll (an example of a return means and a liquid feeding rotating body)
140 Developing device 142 Storage tank 143 First curved wall 144 Second curved wall 146 Auxiliary roll (an example of a return means, a counter member, a liquid feeding rotating body, and a rotating member)
G Liquid developer

Claims (6)

A storage tank for storing a liquid developer;
A developing rotator for holding the liquid developer on the outer peripheral surface;
Supply rotation that is provided so as to be able to rotate with the developing rotator aligned with the rotation axis direction, and a part of the developing rotator is immersed in the liquid developer in the storage tank while rotating to supply the liquid developer to the outer peripheral surface of the developing rotator. Body,
A gap that allows the liquid developer to flow is formed at a position that is immersed in the liquid developer in the storage tank and faces the supply rotator, and is closer to the bottom of the storage tank than the surface facing the supply rotator. An opposing member arranged so that
Disposed downstream of the pre-Symbol counter member in the direction of rotation of said supply rotary member, through the gap, and return means returning to the upstream side of the opposing member of the liquid developer in the rotational direction,
A developing device.   The developing device according to claim 1, wherein the return unit is a liquid-feeding rotary body that is rotatably provided and feeds the liquid developer into the gap while rotating. The developing device according to claim 1, wherein a gap between the supply rotating body and the facing member is narrowed toward a downstream side in the rotation direction . The developing device according to claim 1, wherein the facing member is disposed below a lowermost point of an outer peripheral surface of the supply rotating body in a vertical direction . The developing device according to claim 1, further comprising a developer supply unit that supplies a liquid developer from the deepest portion of the storage tank into the storage tank . An image carrier that is rotatably provided and holds a latent image on the outer peripheral surface;
The developing device according to any one of claims 1 to 5, wherein a liquid developer is supplied to a latent image on the image carrier to form a developer image;
Transfer means for transferring the developer image of the image carrier to a recording medium;
An image forming apparatus.

Images