+

WO2018101484A1 - Appareil de formation d'image - Google Patents

Appareil de formation d'image Download PDF

Info

Publication number
WO2018101484A1
WO2018101484A1 PCT/JP2017/043893 JP2017043893W WO2018101484A1 WO 2018101484 A1 WO2018101484 A1 WO 2018101484A1 JP 2017043893 W JP2017043893 W JP 2017043893W WO 2018101484 A1 WO2018101484 A1 WO 2018101484A1
Authority
WO
WIPO (PCT)
Prior art keywords
toner
voltage
image
developer
liquid
Prior art date
Application number
PCT/JP2017/043893
Other languages
English (en)
Japanese (ja)
Inventor
良太 藤岡
Original Assignee
キヤノン株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by キヤノン株式会社 filed Critical キヤノン株式会社
Publication of WO2018101484A1 publication Critical patent/WO2018101484A1/fr

Links

Images

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer

Definitions

  • the present invention relates to an electrophotographic image forming apparatus that forms an image using a liquid developer.
  • an electrostatic latent image formed on a charged photosensitive drum is developed into a toner image using a liquid developer containing particulate toner and carrier liquid, and the developed toner image is transferred to a recording material.
  • Forming devices are known.
  • the liquid developer is accommodated in the mixer and is supplied from the mixer to the developing device.
  • the electrostatic latent image formed on the rotating photosensitive drum is developed into a toner image by the liquid developer carried on the rotating developing roller.
  • Such a toner image is developed by moving charged toner in a liquid developer layer formed between the developing roller and the photosensitive drum in accordance with an electric field formed by applying a developing voltage to the developing roller. (So-called electrophoresis).
  • the mobility of the toner in the liquid developer that is, the ease of movement of the toner is proportional to the toner charge amount.
  • the toner charge amount decreases, the toner mobility decreases, and when the toner charge amount increases, the toner mobility increases.
  • the charge state of the toner is affected and the toner charge amount changes.
  • the toner concentration of the liquid developer (the ratio of the weight of the toner to the total weight of the liquid developer, the TD ratio) is appropriate, and the amount of toner in the liquid developer is sufficient. In spite of this, it is easy to develop an uneven toner image having a low image density.
  • the amount (that is, concentration) of the charge control agent contained in the liquid developer can be adjusted according to the conductivity (that is, resistivity) of the liquid developer.
  • An image forming apparatus is proposed (Patent Document 1).
  • the liquid developer contains a charge control agent that gives a charge to the toner surface. Therefore, in the apparatus described in US Pat. No. 8,987,321, the charge amount of the toner is increased by replenishing the charge control agent and increasing the concentration of the charge control agent in the liquid developer when the resistivity is low. . Note that the resistivity of the liquid developer decreases according to the replenishment amount of the charge control agent.
  • the above-described apparatus does not supply the charge control agent, and the toner charge amount and thus the toner mobility cannot be increased. Therefore, density unevenness (flow pattern) caused by separation of toner when the liquid developer has a high resistivity and toner mobility remains low, and the liquid layer of the liquid developer is separated into the developing roller side and the photosensitive drum side. It was easy to occur.
  • a rotatable image carrier a charging unit that charges the image carrier, an exposure unit that exposes the charged image carrier to form an electrostatic latent image, A liquid developer containing toner, a carrier liquid, and a charge control agent is carried and rotated, and an electrostatic latent image formed on the image carrier by applying a development voltage is converted into a toner image by the liquid developer.
  • a developer carrier to be developed A resistivity detector that detects the resistivity of the liquid developer, a density adjuster that adjusts the concentration of the charge control agent in the liquid developer, and an acquisition unit that acquires information about the mobility of the toner in the liquid developer;
  • An image forming apparatus comprising: a control unit configured to change a potential difference between the density of the charge control agent or the surface potential of the image carrier and the development voltage based on the resistivity and information on the mobility of the toner.
  • FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to the present exemplary embodiment.
  • FIG. 2 is a cross-sectional view showing the configuration of the image forming unit.
  • FIG. 3 is a control block diagram showing an image density maintenance control system.
  • FIG. 4 is a graph showing the relationship between toner mobility and resistivity.
  • FIG. 5 is a flowchart showing image density maintenance control.
  • FIG. 6 is a graph showing the relationship between the film forming voltage and the density of the patch toner image.
  • FIG. 7 is a diagram showing a control count table.
  • FIG. 8 is a control block diagram showing another embodiment of the image density maintenance control system.
  • An image forming apparatus 100 shown in FIG. 1 is an intermediate transfer type printer having one image forming unit P.
  • a printer having one image forming portion P is shown.
  • image forming portions for yellow, magenta, cyan, and black are arranged side by side in the rotation direction of the intermediate transfer drum 60.
  • a tandem type full color printer may also be used.
  • the image forming apparatus 100 forms an image formed in accordance with image information from an external host device (not shown) such as a personal computer or an image reading device that can communicate with the apparatus main body, as a recording material S (for example, paper, OHP sheet, etc.). Can be output.
  • the image forming apparatus 100 primarily transfers the toner image on the photosensitive drum formed by the image forming unit P to the intermediate transfer drum 60, and then the toner image on the intermediate transfer drum to the recording material S conveyed from the cassette 80. Secondary transfer.
  • the recording material S onto which the toner image has been transferred in this manner is conveyed to the fixing device 90, and the toner image is fixed to the recording material S when heated and pressurized or irradiated with ultraviolet rays by the fixing device 90.
  • the recording material S on which the toner image is fixed is discharged out of the machine body.
  • a charging roller 51, an exposure device 52, a developing device 53, and a first cleaning device 54 are disposed so as to surround the photosensitive drum 50.
  • the photosensitive drum 50 serving as an image carrier is an organic photoconductor in which an amorphous silicon photosensitive layer is formed on the outer peripheral surface of a conductive aluminum cylinder, and more preferably a silicone resin protective layer is formed on the photosensitive layer. OPC) drum.
  • the photosensitive drum 50 is rotated in a direction indicated by an arrow R1 in the drawing at a predetermined process speed (for example, a peripheral speed of 350 mm / sec) by a motor (not shown).
  • a charging roller 51 serving as a charging unit charges the surface of the photosensitive drum 50 to a uniform negative polarity dark portion potential. That is, the charging roller 51 charges the surface of the rotating photosensitive drum 50 to a predetermined potential when a DC voltage is applied from the charging power source V1. In the present embodiment, the surface of the photosensitive drum 50 is charged to a surface potential (dark portion potential) of ⁇ 500 V, for example.
  • the contact charging type charging roller 51 is not limited to a non-contact charging type corona charger.
  • the photosensitive drum 50 is uniformly charged to a predetermined polarity and potential by the charging roller 51, and then subjected to image exposure by the laser light L from an exposure device 52 as an exposure unit. That is, the exposure device 52 scans the surface of the charged photosensitive drum 50 by scanning a laser beam modulated in accordance with an image signal sent from the external host device (not shown) to the image forming apparatus 100 with a rotating mirror. Laser scanning exposure. By this laser scanning exposure, the potential of the portion (exposed portion) irradiated with the laser light L on the photosensitive drum is lowered, so that an electrostatic latent image corresponding to the scanned and exposed image information is formed on the rotating photosensitive drum. Is formed.
  • the exposure part potential (bright part potential) of the photosensitive drum 50 is, for example, ⁇ 150V.
  • a developing device 53 is disposed on the opposite side of the intermediate transfer drum 60 across the photosensitive drum 50.
  • the electrostatic latent image formed on the photosensitive drum 50 is developed into a toner image with a liquid developer by the developing device 53.
  • the liquid developer is supplied from the developing device 53 to the photosensitive drum 50, whereby the liquid developer is provided between the developing device 53 (developing roller 11 described in detail later) and the photosensitive drum 50.
  • the liquid layer is formed, and the toner image can be developed through this liquid layer.
  • the developing device 53 contains a liquid developer in which particulate toner as a dispersoid is dispersed in a carrier liquid as a dispersion medium.
  • the toner is a resin toner having a colorant and a binder as main components, and a charging auxiliary agent or the like added thereto.
  • the toner has an average particle diameter of about 1 ⁇ m.
  • the carrier liquid is a non-volatile liquid having a high resistance and a low dielectric constant, for example, a volume resistivity adjusted to 1E + 9 ⁇ ⁇ cm or more, a relative dielectric constant of 10 or less, and a viscosity of 0.1 to 100 cP.
  • the carrier liquid a liquid mainly composed of an insulating solvent such as silicone oil, mineral oil, Isopar M (registered trademark, manufactured by Exxon), and a charge control agent or the like added as necessary can be used. Further, liquid monomers that are cured by ultraviolet rays can be used as long as they are within the above-described physical property values.
  • a toner in which the toner mass percent concentration in the liquid developer is adjusted to 1 to 10% is used.
  • the liquid developer contains a charge control agent that gives a negative charge to the toner surface. By adjusting the concentration of the charge control agent in the liquid developer, the toner charge amount and thus the toner mobility change.
  • Known charge control agents can be used.
  • Specific compounds include oils and fats such as linseed oil and soybean oil; alkyd resins, halogen polymers, aromatic polycarboxylic acids, acidic group-containing water-soluble dyes, oxidation condensates of aromatic polyamines, cobalt naphthenate, naphthenic acid Metal soaps such as nickel, iron naphthenate, zinc naphthenate, cobalt octylate, nickel octylate, zinc octylate, cobalt dodecylate, nickel dodecylate, zinc dodecylate, aluminum stearate, cobalt 2-ethylhexanoate; Sulfonic acid metal salts such as petroleum sulfonic acid metal salts and metal salts of sulfosuccinic acid esters; phospholipids such as lecithin; salicylic acid metal salts such as t-butylsalicylic acid metal complexes; polyvin
  • An intermediate transfer drum 60 as an intermediate transfer member is disposed to face the photosensitive drum 50 and abuts against the photosensitive drum 50 to form a primary transfer portion T1 of the toner image.
  • a positive primary transfer voltage (for example, 300 V) is applied to the intermediate transfer drum 60 by a high voltage power supply (not shown), so that a negatively charged toner image on the photosensitive drum can be transferred to the intermediate transfer drum 60. .
  • the liquid developer is supplied from the photosensitive drum 50 to the intermediate transfer drum 60, and the toner image can be transferred through the liquid developer liquid layer formed between the photosensitive drum 50 and the intermediate transfer drum 60. become.
  • the toner image transferred to the intermediate transfer drum 60 is irradiated with light by an optical sensor 62 as image density detection means, and the amount of reflected light is detected.
  • the optical sensor 62 is disposed opposite the outer peripheral surface of the intermediate transfer drum 60 on the downstream side of the primary transfer portion T1 and the upstream side of the secondary transfer portion T2 in the rotational direction of the intermediate transfer drum 60.
  • the first cleaning device 54 rubs a cleaning blade against the photosensitive drum 50 to collect the primary transfer residual toner remaining on the photosensitive drum after the primary transfer. At this time, the first cleaning device 54 removes the carrier liquid together with the primary transfer residual toner from the photosensitive drum 50 and discharges it to a waste liquid tank (not shown).
  • a secondary transfer roller 70 is disposed on the opposite side of the photosensitive drum 50 across the intermediate transfer drum 60.
  • the intermediate transfer drum 60 abuts on the secondary transfer roller 70 to form a secondary transfer portion T2 which is a toner image transfer nip portion to the recording material S.
  • the surface of the secondary transfer roller 70 is rotated in the same direction as the surface of the intermediate transfer drum 60 at the secondary transfer portion T2.
  • a toner image is secondarily transferred from the intermediate transfer drum 60 to the recording material S by applying a secondary transfer voltage (for example, 1500 V) to the secondary transfer roller 70 from a high voltage power source (not shown).
  • a secondary transfer voltage for example, 1500 V
  • the recording material S is conveyed to the secondary transfer portion T2 in synchronization with the toner image primarily transferred to the intermediate transfer drum 60 passing through the secondary transfer portion T2.
  • the secondary transfer residual toner remaining on the intermediate transfer drum 60 after the secondary transfer is collected by the second cleaning device 61 rubbing the intermediate transfer drum 60.
  • the second cleaning device 61 removes the carrier liquid together with the secondary transfer residual toner from the intermediate transfer drum 60 and discharges it to a waste liquid tank (not shown).
  • the developing device 53 includes a developing container 10 forming a casing, a developing roller 11, a squeeze roller 12, a cleaning roller 13, an electrode segment 14, and the like.
  • the developer container 10 contains a liquid developer.
  • the upper portion of the developing container 10 facing the photosensitive drum 50 is opened, and the developing roller 11 is rotatably disposed so that a part of the developing container 10 is exposed to the opening.
  • the developing roller 11 as the developer carrying member is rotated in the same direction on the surface facing the photosensitive drum 50 (in the direction of arrow R3).
  • the developing roller 11 is made of, for example, ester urethane rubber.
  • the electrode segment 14 as a film forming electrode is opposed to the developing roller 11 with a predetermined gap (for example, 0.5 mm). Has been placed.
  • the liquid developer is pumped into the gap by the rotational force of the developing roller 11.
  • the electrode segment 14 is arranged so that the elevation angle of the section where the electrode segment 14 faces as viewed from the center of the developing roller 11 is 70 degrees.
  • the electrode segment 14 forms an electric field between the electrode roller 14 and the developing roller 11 by applying a film forming voltage of ⁇ 500 V, for example, by the electrode power source V5.
  • a film forming voltage of ⁇ 500 V for example, by the electrode power source V5.
  • An ammeter 32 is connected to the electrode segment 14.
  • An ammeter 32 as a first current detection unit detects a current flowing between the electrode segment 14 and the developing roller 11.
  • a squeeze roller 12 as a compression member is disposed downstream of the electrode segment 14 in the rotation direction of the developing roller 11. The squeeze roller 12 is in contact with the developing roller 11 to form a nip portion N1.
  • a squeeze voltage of ⁇ 400 V for example, is applied to the squeeze roller 12 by a squeeze power supply V4. Further, an ammeter 31 is connected to the squeeze roller 12. An ammeter 31 as a second current detection unit detects a current flowing between the squeeze roller 12 and the developing roller 11.
  • the squeeze roller 12 compresses the toner to the developing roller 11 side (developer carrier side). Further, the squeeze roller 12 regulates the amount of the carrier liquid of the liquid developer formed on the surface of the developing roller 11, and the liquid developer formed on the surface of the developing roller after passing through the nip portion N1.
  • the thickness of the liquid layer K (height in the developing roller radial direction) is made substantially uniform. The liquid developer that has not passed through the nip portion N1 of the squeeze roller 12 is returned to the liquid developer accommodated in the developing container 10.
  • the above-described squeeze roller 12 is formed of, for example, stainless steel (SUS) having substantially no electrical resistance, but may be formed of other types as long as it has similar electrical characteristics.
  • the squeeze roller 12 has a surface roughness (Rz) of 0.1 ⁇ m or less. This is because an appropriate amount of liquid developer (mainly carrier liquid) can be carried when passing through the nip portion N1, and a uniform layer of toner is formed on the liquid layer K of the liquid developer after passing through the nip portion N1. It is for forming.
  • the developing roller 11 is applied with a developing voltage of ⁇ 300 V, for example, by a developing power source V2 as a developing voltage applying means while being in contact with the photosensitive drum 50.
  • the fog removal potential also referred to as Vback
  • the fog removal potential is changed according to the development voltage applied by the development power supply V2.
  • the development voltage is changed, the development contrast, which is the potential difference between the exposure portion potential of the photosensitive drum 50 and the development voltage, also changes.
  • the exposure portion potential is ⁇ 150 V and the development voltage is ⁇ 300 V
  • the development contrast is 150 V (absolute value, the same applies hereinafter).
  • the electrostatic latent image on the photosensitive drum is developed into a toner image. That is, the liquid developer transported to the developing position G by the developing roller 11 is transported to the developing roller 11 and the photosensitive drum 50 and is divided into the developing roller side and the photosensitive drum side. A layer is formed. Specifically, a part of the carrier liquid of the liquid developer mainly moves from the developing roller side to the photosensitive drum side. The toner in the liquid developer transported to the development position G is selectively attached to the electrostatic latent image formed on the photosensitive drum 50 by the electric field by the development voltage through the liquid layer of the liquid developer. . In this way, the electrostatic latent image on the photosensitive drum is developed into a toner image.
  • the developing position G is a developing nip portion N2 (see FIG. 1) formed by the developing roller 11 and the photosensitive drum 50.
  • a cleaning roller 13 as a removing member is disposed downstream of the developing position G in the rotation direction of the developing roller 11.
  • the cleaning roller 13 is made of, for example, stainless steel (SUS).
  • the cleaning roller 13 is in contact with the developing roller 11 to form a nip portion N3.
  • the cleaning roller 13 electrically removes the toner remaining on the developing roller after passing through the developing position G at the nip portion N3 and removes the carrier liquid remaining on the developing roller by applying pressure.
  • the cleaning roller 13 can remove the toner from the developing roller 11 by applying a removal voltage with a potential difference of, for example, +200 V from the developing roller 11 by the cleaning power source V3.
  • An ammeter 30 is connected to the cleaning roller 13.
  • An ammeter 30 as third current detection means detects a current flowing between the developing roller 11 and the cleaning roller 13.
  • the toner removed by the cleaning roller 13 is collected from the cleaning roller 13 by the blade member 15 having the same potential as that of the cleaning roller 13.
  • the blade member 15 is made of, for example, stainless steel (SUS).
  • the hardness of the blade member 15 may be equal to or lower than that of the cleaning roller 13.
  • the toner and the carrier liquid removed by the cleaning roller 13 are returned to the mixer 20 as a storage container by a pump (not shown) together with the liquid developer that has not passed through the nip portion N1.
  • the developer container 10 is connected with a mixer 20 containing a liquid developer.
  • the mixer 20 can supply a liquid developer produced by mixing and dispersing toner in a carrier liquid at a predetermined ratio into a developing container by a pump (not shown).
  • the replenishing toner is accommodated in the toner replenishing device 21 and the replenishing carrier liquid (hereinafter referred to as replenishing liquid) is accommodated in the replenishing liquid replenishing device 22, respectively.
  • the replenishing liquid replenishing device 22 as the density adjusting means (replenishing liquid replenishing means) stores a replenishing liquid having a relatively higher resistivity than the liquid developer in the initial state, that is, not yet used. ing.
  • the replenisher does not contain toner and charge control agent.
  • a replenisher or toner is supplied to the mixer 20 based on the toner concentration of the liquid developer detected by a toner concentration sensor (not shown) provided in the mixer.
  • the mixer 20 mixes the supplied replenisher and toner and disperses the toner in the carrier liquid.
  • the toner concentration of the liquid developer is maintained constant.
  • the mixer 20 is connected with a control agent replenishing device 23 as a concentration adjusting means (control agent replenishing means) so that the charge control agent is replenished as necessary (FIG. 5 described later). reference).
  • the charge amount of the toner in the liquid developer increases as the charge control agent is replenished.
  • the resistivity of the liquid developer decreases as the charge control agent is replenished. Further, the resistivity of the liquid developer increases with the replenishment liquid, while the toner mobility decreases with the replenishment liquid replenishment.
  • the image forming apparatus 100 of this embodiment includes a control unit 200.
  • the control unit 200 will be described with reference to FIG. 3 with reference to FIG. 1 and FIG.
  • FIG. 3 shows an image density maintenance control system, and various devices such as a motor and a power source for operating the image forming apparatus 100 are connected to the actual control unit 200 in addition to the illustration. Since it is not the gist of the invention, illustration and description thereof are omitted.
  • the control unit 200 as a control unit performs various controls of the image forming apparatus 100 such as an image forming operation, and includes a CPU (Central Processing Unit) (not shown).
  • the control unit 200 is connected to a memory 201 such as a ROM or RAM as a storage unit or a hard disk device.
  • the memory 201 stores various programs and data for controlling the image forming apparatus 100.
  • the control unit 200 can execute the image forming job stored in the memory 201 and operate the image forming apparatus 100 to perform image formation.
  • control unit 200 can execute adjustment control for adjusting the concentration of the charge control agent and the charging voltage in the liquid developer in order to develop the toner image with an appropriate image density during image formation.
  • the control unit 200 has a function of obtaining the resistivity of the liquid developer as resistivity detection means. These will be described later (see FIG. 5).
  • the memory 201 stores a plurality of film formation voltage values used when determining the resistivity of the liquid developer, a mobility table used when determining the toner mobility (see FIG. 5 and Table 1 described later), and the like. Is memorized. Note that the memory 201 can temporarily store calculation processing results associated with the execution of various control programs.
  • An image forming job is a series of operations from the start of image formation to the completion of the image forming operation based on a print signal for forming an image on a recording material.
  • the pre-operation necessary for ending the image formation is completed through the image forming process.
  • It is a series of operations up to. Specifically, it refers to the period from pre-rotation (preparation operation before image formation) after receiving a print signal (reception of an image formation job) to post-rotation (operation after image formation). , Including paper space.
  • the time of non-image formation is, for example, at the time of pre-rotation, at the time of post-rotation, or between sheets.
  • the pre-rotation period the photosensitive drum 50 and the intermediate transfer drum 60 are started to rotate without receiving a print signal at the start of image formation and forming a toner image, and then the exposure to the photosensitive drum 50 is started. It is a period.
  • the post-rotation period is a period from the end of the last image formation of the image forming job until the rotation of the photosensitive drum 50 and the intermediate transfer drum 60 that are continuously rotated without forming a toner image is stopped.
  • the paper interval is a period between image areas corresponding to the recording material S. When various controls are performed during the paper interval, the paper interval may be extended as appropriate.
  • the control unit 200 includes a charging power source V1, a developing power source V2, a cleaning power source V3, a squeeze power source V4, an electrode power source V5, a replenishing liquid replenishing device 22, a control agent replenishing device 23, ammeters 30 to 32, exposure.
  • a device 52 and an optical sensor 62 are connected.
  • the control unit 200 controls the charging power source V1 to apply a DC voltage to the charging roller 51, thereby charging the surface of the photosensitive drum to a predetermined potential.
  • the control unit 200 controls the exposure device 52 to expose the charged photosensitive drum surface, thereby forming an electrostatic latent image on the photosensitive drum.
  • the control unit 200 controls the electrode power source V5 as the first voltage applying unit to apply a film forming voltage to the developing roller 11 so that the toner is carried on the developing roller 11 together with the carrier liquid.
  • the control unit 200 controls the squeeze power source V4 to apply a squeeze voltage to the squeeze roller 12, thereby allowing the liquid developer containing toner at a high density and having a regulated thickness to pass through the nip portion N1. 11 is supported.
  • the controller 200 controls the developing power supply V2 to apply a developing voltage to the developing roller 11, thereby developing the electrostatic latent image on the photosensitive drum into a toner image.
  • the control unit 200 controls the cleaning power source V3 as the third voltage applying unit to apply a neutralizing voltage to the cleaning roller 13, thereby removing the toner remaining on the developing roller after development.
  • the controller 200 can acquire the current value of the current detected by each of the ammeters 30 to 32 when the film formation voltage, squeeze voltage, and removal voltage are applied. Further, the control unit 200 can control the replenishing liquid replenishing device 22 to cause the mixer 20 to replenish the replenishing liquid. Further, the control unit 200 can control the control agent supply device 23 to supply the mixer 20 with the charge control agent.
  • the mobility of charged particles in the liquid of the liquid developer can be expressed by a Stokes equation as shown in the following equation 1.
  • the moving speed of the charged particles is “v”
  • the electric field applied to the liquid developer is “E”
  • the charge of the charged particles is “Q”
  • the viscosity of the liquid developer is “ ⁇ ”
  • the average of the charged particles The radius is represented by “ ⁇ ”.
  • Equation 1 From Equation 1, it can be understood that the greater the development contrast that affects the charge (Q) of the toner as charged particles or the electric field (E) applied to the liquid developer, the higher the mobility of the toner in the liquid developer. . Further, since the toner charge amount depends on the surface area (4 ⁇ 2 ) of the toner, the larger the toner particle diameter, the higher the toner mobility. Further, as already described, the toner mobility varies depending on the concentration of the charge control agent in the liquid developer.
  • the toner mobility can be in the range of 1.0 ⁇ 10 ⁇ 8 to 1.0 ⁇ 10 ⁇ 12 (m 2 / (V ⁇ s)).
  • the resistivity of the liquid developer can be in the range of 1.0 ⁇ 10 8 to 1.0 ⁇ 10 12 ( ⁇ ⁇ cm).
  • FIG. 4 The relationship between the toner mobility and the resistivity obtained in advance by experiments is shown in FIG. 4 is divided according to the density unevenness of the developed toner image and the flow pattern, and is stored in the memory 201 in advance.
  • Category 1 to 15 shown in FIG. 4 represents the state of the liquid developer in terms of resistivity and toner mobility, and the state of the liquid developer affects the image density of the toner image and the flow pattern generation state.
  • the toner mobility is about 1.0 ⁇ 10 ⁇ 12 (m 2 / (V ⁇ s)), which is lower than the initial state
  • a flow pattern is likely to occur at a development contrast of about 200V.
  • the flow pattern is a difference in the amount of applied toner of several millimeters to several tens of microns that can be caused by fluctuations in the amount of toner that moves from the developing roller to the photosensitive drum when the liquid layer of the liquid developer is separated. It is density unevenness.
  • the fog removal potential can be reduced from 200 V to about 150 V. This is because when the resistivity of the liquid developer is lowered, the surface potential of the photosensitive drum 50 is lowered by the liquid developer supplied from the developing roller 11 to the photosensitive drum 50. When the fog removal potential is reduced, density unevenness due to the so-called fog, in which the toner scatters other than the electrostatic latent image formed on the photosensitive drum 50 from the developing roller 11 is likely to occur.
  • Toner mobility 1.0 ⁇ 10 -9 ⁇ 1.0 ⁇ 10 -11 (m 2 / (V ⁇ s)), resistivity of 1.0 ⁇ 10 9 ⁇ 1.0 ⁇ 10 11 ( ⁇ ⁇ cm ), It is difficult to develop an uneven toner image having a low image density without generating a flow pattern. More preferably, the toner mobility is within a predetermined first range of 1.0 ⁇ 10 ⁇ 10 to 1.0 ⁇ 10 ⁇ 11 (m 2 / (V ⁇ s)), and the resistivity is 1.0 ⁇ 10 10. It may be within a predetermined second range of ⁇ 1.0 ⁇ 10 11 ( ⁇ ⁇ cm) (here, “section 12” in FIG. 4). The liquid developer in the initial state is in the “section 12” state.
  • FIG. 4 is used to explain changes in toner mobility and resistivity when the charge control agent is supplied and when the supply liquid is supplied.
  • the charge control agent is replenished, as described above, the toner mobility is increased while the resistivity is decreased.
  • the state of the liquid developer is “section 8” and the charge control agent is replenished, the state changes to “section 11” on the lower left of the drawing.
  • the charge control agent is replenished, the state changes from “Section 11” to “Section 13”.
  • the fog removal potential is remarkably small, so that fog is likely to occur.
  • the toner mobility is lowered while the resistivity is increased.
  • the charge control agent is supplied in the case of “section 11”
  • the state changes to “section 8” on the upper right side of the drawing.
  • the carrier liquid is replenished, the state changes from “Section 8” to “Section 4”.
  • the toner mobility is too low in the “category 4” state, a flow pattern is likely to occur.
  • the state of the liquid developer is diagonally upward between the “sections” shown in the matrix in FIG. Or it can change so that it may move only diagonally to the left.
  • the state of the liquid developer decreases with the formation of the image, the toner mobility decreases as the charge control agent is consumed and the toner deteriorates, and the resistivity is affected by the increase of foreign matters and the generation of ions in the liquid developer. Can be reduced.
  • FIG. 5 shows image density maintenance control according to this embodiment.
  • the control unit 200 executes setting control during non-image formation. For example, the control unit 200 can execute maintenance control at the time of pre-processing of an image forming job, between every 5000 sheets, or at the time of pre-processing of the next image forming job after image formation for every 5000 sheets.
  • the control unit 200 detects the resistivity of the liquid developer (S1).
  • the resistivity of the liquid developer is detected using the current value of the current flowing between the developing roller 11 and the squeeze roller 12 detected by the ammeter 31. That is, the control unit 200 detects the current developer by the ammeter 31 after the liquid developer carried on the rotating developing roller 11 reaches the squeeze roller 12 in a state where no film forming voltage is applied by the electrode power source V5. Get the current value of the current. Then, the control unit 200 converts the known resistivity of the developing roller 11, the current value flowing through the developing roller 11, the squeeze voltage applied by the squeeze power source V 4 as the second voltage application unit, and the current value of the ammeter 31. Based on this, the resistivity of the liquid developer is obtained.
  • the detection of the resistivity is executed when the execution of the main maintenance control is started and when the charge control agent and the replenisher are supplied in the control process (see S5) described later.
  • the control unit 200 acquires information on the toner mobility of the liquid developer after detecting the resistivity (S2).
  • information on toner mobility is acquired by the following method.
  • the controller 200 applies a plurality of different film forming voltages of ⁇ 225, ⁇ 250, ⁇ 275, and ⁇ 300 V while keeping the squeeze voltage, the developing voltage, and the charging voltage constant, and applies a patch toner image to the photosensitive drum 50. Are formed sequentially.
  • the control unit 200 transfers the patch toner image formed on the photosensitive drum 50 to the intermediate transfer drum 60. Based on the density of the patch toner image on the intermediate transfer drum 60 detected by the optical sensor 62, the control unit 200 obtains the relationship between the applied film forming voltage and the density of the patch toner image.
  • FIG. 6 shows an example of the relationship between the film forming voltage and the density of the patch toner image.
  • the horizontal axis in FIG. 6 indicates the electrode bias, and the vertical axis indicates the density of the patch toner image.
  • the slope of the change amount of the film formation voltage and the change amount of the density of the patch toner image is 0.017 (au / V) (indicated by the dotted line in the figure), and the slope is 0.
  • Two different cases in the case of 0085 (au / V) (indicated by a solid line in the figure) are shown.
  • the control unit 200 refers to the mobility table stored in the memory 201 and identifies the toner mobility associated with the obtained inclination.
  • Table 1 shows the mobility table. As shown in Table 1, in the mobility table, the toner mobility is associated with each inclination of the change amount of the film formation voltage and the change amount of the density of the patch toner image.
  • the control unit 200 identifies, based on the resistivity and the toner mobility, which state of “category 1 to 15” shown in FIG. 4 corresponds to the current state of the liquid developer. (S3).
  • the resistivity is referred to here when the resistivity is detected by the process of S1.
  • the classification is shifted in accordance with the change in the development voltage in the control processing (see S5) described later, the classification is specified without referring to the resistivity.
  • the control unit 200 determines whether or not the identified category is a predetermined category (here, category 12) (S4).
  • control unit 200 executes a different control process for each division (S5). Thereafter, the control unit 200 returns to S1 and repeats the processes of S1 to S4 described above.
  • control part 200 ends this maintenance control.
  • the control unit 200 decreases the development voltage. For example, if the classification is “Category 10”, the development voltage is lowered to shift to “Category 11”. When the development voltage is lowered, only the fog removal potential is increased, and the resistivity is not actually increased, but the same effect as when the resistivity is substantially increased can be obtained. As a result, by increasing the fog removal potential that has decreased with the decrease in resistivity, the toner image can be developed with the same image density as before the decrease in resistivity without causing fogging.
  • the control unit 200 replenishes the charge control agent. For example, if the classification is “Category 3”, the charge control agent is replenished to move to “Category 7”. Alternatively, if the category is “category 7”, the process proceeds to “category 10” by supplying the charge control agent. In this case, the resistivity decreases as the charge control agent is replenished, but the toner mobility can be increased to the first range.
  • the control unit 200 replenishes the replenisher. For example, if the classification is “Category 13”, the supply liquid is replenished to move to “Category 11”. In this case, the toner charge amount decreases with the replenishment of the replenisher, while the resistivity increases.
  • the toner mobility is changed so as to first bring the toner mobility within the first range.
  • the state of the liquid developer is changed by circulating between the mixer 20 and the developing device 53. That is, even if the charge control agent or the replenisher is supplied to the mixer 20, the time required for the liquid developer to make a round until the concentration of the charge control agent in the circulating liquid developer becomes constant (for example, 3 minutes). ).
  • development voltage control is immediate. Therefore, in the present embodiment, in consideration of the fact that the toner mobility is first changed by replenishing the charge control agent and the fog removal potential (Vback) is reduced accordingly, the developing voltage is lowered to recover the reduced fog removal potential. I have to.
  • the control unit 200 replenishes the charge control agent and shifts to “category 6”.
  • the amount of charge control agent to be replenished per time is determined in advance so that the classification is shifted.
  • the controller 200 further replenishes the charge control agent and shifts to “Category 10”.
  • the toner mobility is within the first range, but the fog removal potential decreases as the resistivity decreases. Therefore, the control unit 200 decreases the development voltage to increase the fog removal potential. 11 ”.
  • a reduction value (absolute value) per development voltage is determined in advance so that the division is shifted.
  • the control unit 200 further lowers the development voltage to shift from “Category 11” to “Category 12”. In this way, the control unit 200 can be in the “section 12” state in which it is possible to suppress the development of a non-uniform toner image having a low image density without generating a flow pattern.
  • the replenishment amount per time is determined in advance so that the classification is shifted.
  • charge control agent replenishment control replenishment liquid replenishment control
  • development voltage change control that is, Vback control
  • Vback control development voltage change control
  • the developing voltage is adjusted after the toner mobility is adjusted first.
  • the category is “category 7” in FIG. 4, first, the charge control agent is replenished to move to “category 10”, and then the development voltage is shifted to “category 11” by the first adjustment of the development voltage.
  • the process proceeds to “Category 12”.
  • the present invention is not limited to this, and toner mobility adjustment and development voltage adjustment may be appropriately combined.
  • the first adjustment of the development voltage is performed to shift to “Category 8”, and then the charge control agent is replenished to “Category 11”.
  • the charge control agent may be replenished once and the development voltage adjusted twice.
  • the memory 201 stores in advance a control frequency table that prescribes the control frequency of charge control agent replenishment control or replenishment liquid replenishment control, and development voltage change control for each category shown in FIG. This may be used for maintenance control.
  • FIG. 7 shows a control count table.
  • the control unit 200 determines the number of times of control of the specified section (see S3 in FIG. 4) with reference to the control number table, and performs charge control agent replenishment control or replenishment liquid replenishment control, and development voltage change control according to each control number. What is necessary is just to execute suitably.
  • the current value of the current flowing between the developing roller 11 and the squeeze roller 12 detected by the ammeter 31 is used to detect the resistivity of the liquid developer (see S1 in FIG. 5).
  • the current value of the current detected by the ammeter 30 after the liquid developer carried on the rotating developing roller 11 reaches the cleaning roller 13 in a state where no film forming voltage is applied by the electrode power source V5. May be used.
  • FIG. 8 shows another embodiment of the image density maintenance control system when the conductivity sensor 63 is used. 8 is different from the above-described embodiment shown in FIG. 3 in that a conductivity sensor 63 as a resistivity detecting unit is connected to the control unit 200. Since other configurations and operations are the same as those of the first embodiment, description thereof will be omitted.
  • the conductivity sensor 63 is provided, for example, in the mixer (see FIG. 2), and detects the conductivity of the liquid developer in the mixer.
  • the control unit 200 obtains and uses the resistivity of the liquid developer according to the detection result of the conductivity sensor 63 when executing the above-described image density maintenance control (see FIG. 5).
  • the density of the patch toner image formed with different film formation voltages and transferred onto the intermediate transfer drum 60 in order to acquire information on the toner mobility (see S2 in FIG. 5), the density of the patch toner image formed with different film formation voltages and transferred onto the intermediate transfer drum 60, and Although the relationship with the applied film forming voltage is used, the present invention is not limited to this.
  • information on toner mobility may be acquired based on a change in the current value of the current detected by the ammeter 31 when a constant squeeze voltage is applied by the squeeze power supply V4.
  • information on the toner mobility may be acquired based on a change in the current value of the current detected by the ammeter 30 when a constant removal voltage is applied by the cleaning power supply V3.
  • control agent replenishing device 23 containing the charge control agent is used in order to replenish the liquid developer in the mixer with the charge control agent.
  • the charge control agent may be replenished by introducing a carrier liquid containing the charge control agent into the mixer 20.
  • toner may be replenished by introducing a carrier liquid containing toner into the mixer 20.
  • the intermediate transfer member may be, for example, an intermediate transfer belt formed in an endless belt shape.
  • the present invention provides an electrophotographic image forming apparatus that forms an image using a liquid developer.
  • DESCRIPTION OF SYMBOLS 11 Developer carrier (development roller), 12 ... Compression member (squeeze roller), 13 ... Removal member (cleaning roller), 14 ... Deposition electrode (electrode segment), 22 ... Concentration adjusting means (replenishing liquid replenishing means, replenishing liquid replenishing apparatus), 23... Concentration adjusting means (control agent replenishing means, control agent replenishing apparatus), 30... Third current detecting means (ammeter), 31 ... second current detection means (ammeter), 32 ... first current detection means (ammeter), 50 ... image carrier (photosensitive drum), 51 ... charging means (charging roller), 52...
  • Exposure means (exposure device) 60... Intermediate transfer body (intermediate transfer drum) 62... Image density detection means (optical sensor) 63. , 100 ... Image forming apparatus, 200 ...

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Wet Developing In Electrophotography (AREA)
  • Developing For Electrophotography (AREA)
  • Control Or Security For Electrophotography (AREA)

Abstract

L'invention concerne une unité de commande qui, après (S1) avoir détecté la résistivité d'un révélateur liquide, (S2) acquiert des informations concernant la mobilité de l'encre en poudre du révélateur liquide. Ensuite (S3), l'unité de commande identifie l'état actuel du révélateur liquide sur la base de la résistivité et de la mobilité de l'encre en poudre et (S5) exécute un processus de commande qui est différent pour chaque état identifié (catégorie). L'unité de commande peut exécuter une combinaison appropriée de commande de réapprovisionnement d'agent de commande de charge, de commande de réapprovisionnement avec un liquide de réapprovisionnement, et de commande de changement dans une tension de développement (commande de réglage de Vback). Lorsque ces opérations ont été effectuées, même si Vback est réduite conjointement avec une réduction de la résistivité en raison du réapprovisionnement de l'agent de commande de charge, Vback peut être rétablie en modifiant ensuite la tension de développement. Cela permet de supprimer à la fois la production d'un motif de flux et le développement d'une image d'encre en poudre non uniforme à faible densité d'image.
PCT/JP2017/043893 2016-12-01 2017-11-30 Appareil de formation d'image WO2018101484A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2016234192A JP2018091960A (ja) 2016-12-01 2016-12-01 画像形成装置
JP2016-234192 2016-12-01

Publications (1)

Publication Number Publication Date
WO2018101484A1 true WO2018101484A1 (fr) 2018-06-07

Family

ID=62242143

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2017/043893 WO2018101484A1 (fr) 2016-12-01 2017-11-30 Appareil de formation d'image

Country Status (2)

Country Link
JP (1) JP2018091960A (fr)
WO (1) WO2018101484A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019235641A1 (fr) * 2018-06-07 2019-12-12 キヤノン株式会社 Dispositif d'alimentation en révélateur, dispositif de développement et dispositif d'extraction de séparation

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010526338A (ja) * 2007-04-30 2010-07-29 ヒューレット−パッカード デベロップメント カンパニー エル．ピー． 現像監視方法およびシステム
JP2011070122A (ja) * 2009-09-28 2011-04-07 Dainippon Screen Mfg Co Ltd 画像形成装置、画像形成方法および液体トナー
JP2014191102A (ja) * 2013-03-26 2014-10-06 Fuji Xerox Co Ltd 液体現像剤、画像形成装置、画像形成方法、プロセスカートリッジ、及び液体現像剤カートリッジ
JP2016224191A (ja) * 2015-05-28 2016-12-28 キヤノン株式会社 画像形成装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010526338A (ja) * 2007-04-30 2010-07-29 ヒューレット−パッカード デベロップメント カンパニー エル．ピー． 現像監視方法およびシステム
JP2011070122A (ja) * 2009-09-28 2011-04-07 Dainippon Screen Mfg Co Ltd 画像形成装置、画像形成方法および液体トナー
JP2014191102A (ja) * 2013-03-26 2014-10-06 Fuji Xerox Co Ltd 液体現像剤、画像形成装置、画像形成方法、プロセスカートリッジ、及び液体現像剤カートリッジ
JP2016224191A (ja) * 2015-05-28 2016-12-28 キヤノン株式会社 画像形成装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019235641A1 (fr) * 2018-06-07 2019-12-12 キヤノン株式会社 Dispositif d'alimentation en révélateur, dispositif de développement et dispositif d'extraction de séparation

Also Published As

Publication number Publication date
JP2018091960A (ja) 2018-06-14

Similar Documents

Publication Publication Date Title
JP5424106B2 (ja) 画像形成装置
US9798281B2 (en) Image forming apparatus, image forming system and control method
US9952530B2 (en) Image forming apparatus
JP5637025B2 (ja) 湿式画像形成装置
JP2000214688A (ja) 湿式画像形成装置
WO2018101484A1 (fr) Appareil de formation d'image
US10915038B2 (en) Image forming apparatus
US10732537B2 (en) Image forming apparatus
US9804523B2 (en) Image forming apparatus
US10578995B2 (en) Image forming apparatus
JP7115198B2 (ja) 画像形成装置
JP2009223238A (ja) 画像形成装置
JP2001134027A (ja) 画像形成装置
JP2001100520A (ja) 現像装置および画像形成装置
US11131943B1 (en) Image forming apparatus
US11474465B2 (en) Image forming apparatus including a developing device that develops an electrostatic latent image
JP4281694B2 (ja) 画像形成装置
US10394165B2 (en) Developing device carrying liquid developer
JP7023777B2 (ja) 画像形成装置
JP4032643B2 (ja) 画像形成装置
JP2005189410A (ja) 画像形成装置
JP2023129243A (ja) 画像形成装置
JP2005265923A (ja) 現像装置及び画像形成方法
JP2010128163A (ja) 現像ユニットおよび画像形成装置
JP2006243052A (ja) 液体現像装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17877132

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17877132

Country of ref document: EP

Kind code of ref document: A1

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载