JP5262458B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of stripe image irregularities caused in a solid image when the image is formed by a direct recording system of the configuration in which a toner carrier for carrying a toner has a plurality of electrodes and the toner is turned clouded by generating an electric field that changes in time between the electrodes. <P>SOLUTION: The image forming apparatus has the toner carrier 1 which moves in a predetermined movement direction carrying the charged toner T and which has the plurality of electrodes 111 set at predetermined intervals in the movement direction on a surface. A bias voltage Vs is applied from a voltage applying means 6 to each electrode 111 of the toner carrier 1. The bias voltage Vs in a direction to repel a direction in which the toner T is sucked changes in potential by time. Hence the toner T is turned clouded on the toner carrier 1. A movement speed in a forward direction of the toner carrier 1 is set faster than a movement speed in a forward direction of a recording medium means 3. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus. The present invention relates to an image forming apparatus.

  As a conventional image forming apparatus, an apparatus that directly records an image on a recording medium (including an intermediate transfer medium) with toner (recording material), which is called toner jet, direct toning, or toner projection, is known. Yes. In the present application, “toner” is a generic term for what can be given an image on a recording medium, including toners, image forming particles, fine particles, recording materials (agents) and the like.

For example, Patent Document 1 discloses that a toner supplied from a toner hopper is charged with a charge by frictional charging with a fixed blade or a rotating roller, and is rotated and conveyed, and then between a control pulse applied to a control member and the rotating roller. A device that controls the flying of toner by an electric field is described.
Japanese Unexamined Patent Publication No. 63-136058

  Here, the charged toner is electrostatically attached to the surface of the rotating roller, and the toner needs to be peeled off by a control pulse. Since the rotating roller and the control member have a gap of several hundred μm or more, the control pulse applied for peeling inevitably requires a high voltage of 500 V or more, and the driver cost for control that requires a number corresponding to the pixel is There is also a problem that it becomes very expensive, and further, there is a problem of poor response and time delay because the toner adhering to the rotating roller is peeled off to fly.

Patent Documents 2 and 3 describe a technique in which a control pulse is applied to a control electrode for passing a developer while an alternating bias is applied between the rotating developer support and the control means.
Japanese Patent No. 2933930 Japanese Patent Publication No. 2-52260

  In this configuration, although the problem of responsiveness as in the apparatus described in Patent Document 1 is reduced, a uniform alternating electric field is applied to the entire flying region of the toner so that the developer adheres to the developer support. The time and flight status are repeated. Therefore, it is necessary to apply a strong alternating bias in order to peel off the developer adhering to the developer support, and the peeled toner flies to the control means side vigorously and a lot of developer is applied to the electrodes of the control means. Adhering to the surface is inevitable, and there is a big problem in reliability. Further, since the developer support and the control means have the same gap as described above, the voltage value applied between them is as high as 500 V or more, and an electric field that allows the developer to pass or block is formed with respect to this electric field. Similarly, since the control pulse requires a high voltage value, the problem of the driver cost cannot be solved.

On the other hand, Patent Document 4 describes a configuration in which a developer carrying member has a plurality of electrodes, and an electric field that changes with time is formed between the electrodes to cause toner to fly to the control electrode side.
JP 59-181370 A

  Here, in order to control the passage of the toner that flies near the control electrode and floats, the disadvantage that the control voltage of the devices of Patent Documents 1 to 3 becomes high is solved.

Similar to Patent Document 4, Patent Document 5 has a configuration in which a developer carrying member has a plurality of electrodes, and an electric field that changes with time is formed between the electrodes to cause toner to fly. It is described that the control electrode for controlling the toner is installed on the toner supply side, which has been installed on the recording medium side.
JP 02-226261 A

  In this configuration, the control voltage required to be 400 V in the previous apparatus can be set to 100 V, and when the toner adhering to the print head provided with the control electrode is removed, it can be returned to the toner supply source. Have been described.

In Patent Document 6, toner is supplied by a rotating cylindrical sleeve, and an electrostatic force is passed through the aperture with a printing surface potential and a uniform electric field between the sleeves, and the control electrode surrounding the aperture is opposed to the printing surface side. It is described that a deflection electrode is provided to increase the dot density in the main scanning direction of printing.
JP-T-2001-505146

  Here, it is described that a guard electrode is provided between control electrodes for controlling the passage of toner to prevent interaction between control electric fields.

Japanese Patent Application Laid-Open No. H10-260260 describes a toner supply roller that supplies toner, and a control electrode that controls the flying of the toner and a deflection electrode that deflects the flying path of the toner are disposed on the toner supply roller side of the opening holding member. Has been.
JP 11-301014 A

  However, the control pulse and the rotating roller applied to the control member after the toner supplied from the toner hopper described in Patent Document 1 is charged by charging the toner by friction charging with the fixed blade or the rotating roller and then rotated and conveyed. In a general configuration in which toner flying is controlled by an electric field between the toner and the charged toner is electrostatically attached to the surface of the rotating roller, and the toner needs to be peeled off by a control pulse. However, since the rotating roller and the control member have a gap of several hundred μm or more, the control pulse applied for peeling requires a high voltage of 500 V or more, and the number corresponding to the pixel is necessary for control. Not only will the driver cost be very high, but the toner adhering to the rotating roller will be peeled off and fly away, resulting in poor responsiveness and time delay. There is a problem that may occur.

  Patent Documents 2 and 3 describe a configuration in which a control pulse is applied to the control electrode for passing the developer while applying an alternating bias between the rotating developer support and the control means. Although the problem of responsiveness of the described configuration is reduced, the developer is repeatedly attached to the developer support and the flying state while applying a uniform alternating electric field to the entire flying region of the toner. It is necessary to apply a strong alternating bias in order to peel off the developer adhering to the developer support, and the peeled toner flies to the control means side vigorously and a lot of developer adheres to the electrodes of the control means. There is a big problem in reliability. Further, since the developer support and the control means have the same gap as in the above cited reference 1, the voltage value applied between them is as high as 500 V or more, and the developer is allowed to pass or block against this electric field. Since the control pulse for forming the electric field similarly needs a high voltage value, there is a problem that the problem of the driver cost cannot be solved.

  As described in Patent Document 4, the developer carrying member has a plurality of electrodes, and an electric field that changes with time is formed between the electrodes to fly the toner to the control electrode side. Although the control voltage can be lowered in order to control the passage of toner that flies near the control electrode and floats, the problem remains that toner adheres to the control electrode as time passes.

  As described in Patent Document 5, the developer carrying member has a plurality of electrodes, and an electric field that changes with time is formed between the electrodes to cause the toner to fly, and a control electrode that controls the passage of the toner is used as the toner. In the configuration installed on the supply side, as in Patent Document 4, the control voltage can be lowered, and when the toner adhering to the print head provided with the control electrode is removed, the control voltage is returned to the toner supply source. However, there is a problem that the image quality is lowered and the reliability is lowered due to the toner adhering to the control electrode.

  As described in Patent Document 6, toner is supplied by a rotating cylindrical sleeve, an electrostatic force is passed through the aperture with a printing surface potential and a uniform electric field between the sleeves, and the control electrode surrounding the aperture and the printing surface side are provided. Even in the configuration in which the pair of deflection electrodes is provided and the guard electrode is provided between the control electrodes for controlling the passage of toner, the problem of toner adhesion to the control electrode means remains.

  Even if the configuration is such that a guard electrode is provided on the outside of the flight control electrode as described in Patent Document 7, and toner is prevented from adhering to portions other than the flight control electrode, the toner adheres to the control electrode. However, there remains a problem that the image quality is significantly deteriorated.

  As described above, when adopting a configuration in which a toner carrying body that carries toner has a plurality of electrodes, and an electric field that changes with time is formed between the electrodes to form a cloud of toner, the present inventors According to an experiment, it has been found that when a solid image having a large area (an image in which all areas are filled with toner) is formed, a striped image unevenness occurs in the solid image.

  The present invention has been made in view of the above problems, and has a configuration in which a toner carrying body that carries toner has a plurality of electrodes, and an electric field that changes with time is formed between the electrodes to cloud the toner. An object of the present invention is to reduce striped image unevenness in a solid image when an image is formed by the direct recording method.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A toner carrier that carries a charged toner and moves in a predetermined movement direction, and has a plurality of electrodes provided on the surface at predetermined intervals in the movement direction;
Clouding means for alternately applying a voltage in the direction of attracting and repelling the toner to a plurality of electrodes of the toner carrier;
A recording medium means to which the toner is attached;
A toner control means having a plurality of toner passage openings disposed between the toner carrier and the recording medium means;
Counter electrode means for applying a voltage to the recording medium means side;
A first electrode provided in the toner control means for controlling the flying of the toner from the toner carrier;
A second electrode provided on a surface of the toner control unit facing the toner carrier and distant from the first electrode;
The potential difference between the counter electrode means and the toner carrier is V1, the distance between the counter electrode means and the toner carrier is L1, the potential difference between the second electrode and the counter electrode means is V2, the second When the distance from the electrode through the first electrode to the counter electrode means is L2,
V1 / L1 <V2 / L2
Voltage application means for applying a voltage satisfying the relationship to the toner carrier, the first electrode, the second electrode, and the counter electrode means,
When the moving direction of the recording medium means is the forward direction, the moving speed of the toner carrier in the forward direction is different from the moving speed of the recording medium means in the forward direction.

  Here, the moving speed of the toner carrier in the forward direction can be faster than the moving speed of the recording medium means in the forward direction.

  The voltage applied to the electrode of the toner carrying member is Vs, the voltage applied to the counter electrode means is Vp, the voltage applied to the first electrode of the toner control means is Vc, and the second voltage of the toner control means is 2nd. When the voltage applied to the electrode is Vg, when the toner is allowed to pass through the toner passage opening, the polarity is opposite to the charging polarity of the toner, and the relationship is Vp> Vc> Vs> Vg in descending order. Can be configured.

  In this case, when the toner is prevented from passing through the toner passage opening, a voltage having a relationship of Vc <Vg can be applied to the first electrode and the second electrode.

  Further, when the potential of the toner is Vt, a relationship of Vs> Vt> Vg can be established.

  According to the image forming apparatus of the present invention, when the moving direction of the recording medium means is the forward direction, the moving speed of the toner carrier in the forward direction is different from the moving speed of the recording medium means in the forward direction. When forming an image with a direct recording method that has a plurality of electrodes on a toner carrier that carries toner and forms a time-varying electric field between the electrodes to form a cloud of toner, a solid image It is possible to reduce striped image unevenness.

Embodiments of the present invention will be described below with reference to the accompanying drawings. A first embodiment of the present invention will be described with reference to the schematic configuration diagram of FIG.
In this embodiment, a roller-shaped toner carrier 1 that carries the toner T, a recording medium means (recording member) 3 to which the toner T is adhered, and the toner carrier 1 are opposed to the recording medium means 3 with a voltage applied thereto. Toner control having a counter electrode means (back electrode) 5 for applying toner and a plurality of toner passage holes 41 which are a plurality of toner passage openings disposed between the toner carrier 1 and the recording medium means 3 (counter electrode means 5). Means 4 are provided.

  The toner carrier 1 rotates (moves) in the direction of the arrow, and transports the toner T at a predetermined interval (pitch) P in the direction (moving direction: circumferential direction here) in which the toner T is transported to the surface. A plurality of electrodes 111 are formed along an orthogonal direction (here, an axial direction), and each electrode 111 of the toner carrier 1 has a direction repelling a direction in which the toner T is sucked from the voltage application unit 6. A bias voltage Vs whose potential changes with time, which is the voltage of, is applied. As a result, clouding means for clouding the toner T on the toner carrier 1 is configured.

  For example, since a pulsed bias voltage Vs having a frequency of 0.5 KHz to 7 KHz is applied and the distance between the electrodes 111 and 111 is provided at a fine pitch, a strong electric field is formed between the electrodes 111 and 111. Therefore, the toner T flies vigorously from the surface of the electrode 111 that is at a potential repelling the charged polarity of the toner T, and the toner T that has flew is attracted to the electrode 111 to which the potential of the attracting polarity is applied, and a pulse is generated. By switching, the vertical flight according to the pulse frequency is repeated, and the toner T is in a cloud state. In a region where the frequency of the pulse is high, the toner T that has flew upward may change its pulse while flying, and may fly upward again before returning to the surface of the electrode 111.

  At this time, the two-phase inter-electrode pitch P (or n is applied to each of the n electrodes 111) to apply a voltage that alternately repeats the direction of attracting and repelling the toner T between the adjacent electrodes 111. The distance d between the surface of the toner carrier 1 and the side surface of the toner carrier 1 of the toner control means 4 (meaning the surface on the toner carrier 1 side) is The toner carrier 101 and the toner control unit 4 are arranged in a relationship of increasing (p <d).

  That is, in the relationship of p> d, the flying electric field formed on the surface of the electrode 111 of the toner carrier 1 interferes with the ON / OFF electric field on the toner carrier 1 side surface of the toner controller 4, and the loop of the toner controller 4. This is because the electric field is disturbed. Therefore, toner adhesion to the surface of the control electrode 42 is likely to occur. Under the condition of p <d, it is possible to reliably prevent the toner from adhering to the control electrode 42, and a good image can be obtained without changing the density even if continuous dots are printed.

  The toner control means 4 is provided with a plurality of toner passage holes (openings) 41 through which the toner T can pass, and around the toner passage opening 41 around the toner supply side surface (surface on the toner carrier 1 side) of the toner control means 4. A control electrode 42 as a first electrode is provided in a ring shape, and a plurality of toner passage holes 41 are further provided outside the control electrode 42 with respect to the toner passage hole 41 via an insulating region, that is, at a position away from the control electrode 42. A common electrode 43 that is a common second electrode is provided.

  For example, a control pulse Vc as shown in FIG. 2 is applied to the control electrode 42 of the toner control means 4 from a control pulse generating means 7 which is a voltage applying means. In this case, the voltage Vc-on is applied to the control electrode 42 when the toner T is allowed to pass through the toner passage hole 41 (ON state), and the control is performed when the toner T is not allowed to pass (OFF state). A voltage Vc-off is applied to the electrode 42. A voltage Vg is applied to the common electrode 43 from the power supply means 8 which is a voltage applying means. The control electrode 42 of the toner control means 4 can operate only around the toner passage hole 41, but on both the inner wall surface of the toner passage hole 41 or the inner wall surface of the toner passage hole 41 and the periphery on the toner carrier 1 side. It may be provided.

  A back electrode 5 as a counter electrode means is disposed on the back surface of the recording medium means 3, and in order to adhere the toner T that has passed through the toner control means 4 to the recording medium means 3, it is supplied from a bias power supply means 9 that is a voltage applying means. A bias voltage Vp is applied. The recording medium means 3 may be an intermediate transfer recording medium or recording paper on which an image is once formed and then transferred to paper. The bias voltage Vp is applied to the recording medium means 3 by, for example, arranging a back electrode 5 on the back side (side opposite to the toner carrier 1) of the recording medium means 3 and passing the recording medium means 3 on the top surface of the back electrode 5. In the case of an intermediate transfer recording medium, a configuration in which a counter electrode unit is embedded therein or a rear electrode 5 is disposed on the back surface of the intermediate transfer recording medium can be employed.

Next, an example of a specific configuration of the toner control unit 4 will be described with reference to FIG.
In this example, a ring-shaped control electrode 42 having a width of 10 to 100 μm is provided on the surface of the insulating substrate (base material) 45 on the toner supply side (toner carrier 11 side) so as to surround the toner passage hole 41. A common bias voltage Vg is applied to the plurality of toner passage holes 41 at an interval of 20 to 50 μm from 42, that is, through the insulating region formed of the insulating base material 45, on the same surface as the control electrode 42. In this configuration, a common electrode 43 is provided.

  The toner passage hole 41 has a diameter of 30 μm to 150 μm, which is determined by the size of the dot diameter to be formed. The control electrode 42 is connected to a lead pattern 42a for connection to a driver circuit (control pulse generating means: drive circuit) for controlling ON / OFF of the passage of the toner T individually, and the common electrode 43 is a common lead pattern. 43a. Further, the toner passing hole 41 is opened on the printing surface side (the surface on the recording medium means 3 side) of the insulating substrate 45.

  In this way, the common electrode of the toner control unit is configured to surround the outside of the control electrode in a ring shape through the insulating region, so that the bias potential on the recording medium unit side and the common electrode outside the control electrode are Since the electric force formed between them can be formed as an independent electric force line for each toner passing hole, mutual interference (the state of other toner passing holes can be changed) during multi-drive (driving the toner from a plurality of nozzle passing holes) Does not occur.

  Also, by forming the control electrode and the common electrode of the toner control means on the same surface, they can be formed simultaneously in a single manufacturing process, and the electrodes can be made with high accuracy and at low cost.

Another example of the specific configuration of the toner control unit 4 will be described with reference to FIG.
In this example, a ring-shaped control electrode 42 having a width of 10 to 100 μm is provided on the surface of the insulating substrate (base material) 45 on the toner supply side (toner carrier 11 side) so as to surround the toner passage hole 41. The common electrode 43 for applying a common bias voltage Vg to the plurality of toner passage holes 41 is provided in a solid shape so as to cover the entire vacant space with an interval between the insulating regions of 42 to 20 to 50 μm.

  In this way, the common electrode of the toner control unit is configured to be solid on the outside of the control electrode via the insulating region, that is, the common electrode is formed over the entire outside region of the control electrode, so that the recording medium The electric field of the bias potential on the means side can be shielded, toner adhesion to the control electrode can be reduced, and toner utilization efficiency can be improved.

  A specific manufacturing method of such a toner control unit 4 is a resin film such as polyimide, PET, PEN, PES, etc. from the viewpoint of cost and manufacturing process as an insulating member as the base material 45, and has a thickness of 30 μm. A 100 μm film is used, and an Al deposited film of 0.2 μm to 1 μm is first formed on the film surface. Next, in the photolithography process, after applying a photoresist with a spinner, pre-baking and mask exposure are performed, development is performed, and after the photoresist is heated and cured, Al patterning is performed with an Al etching solution. If an electrode pattern is also required on the back surface of the film, it can be performed in the same manner as described above, but a pattern used as a mask for hole processing may be formed on the back surface. The formation of the through hole serving as the toner passage hole 41 can be achieved by mechanical processing using a press after pattern formation, excimer laser processing using a pattern formed on the back surface, or dry etching processing such as sputter etching processing. High-accuracy drilling can be performed.

Next, an example of the toner carrier 1 will be described with reference to FIG. FIG. 5A is a schematic plan view illustrating the toner carrying member in a developed state, and FIG. 5B is a schematic cross-sectional view illustrating the same.
In this example, a plurality of electrodes are provided on the surface of the toner carrying member, and two pairs of electrodes for every other pair are provided in common, and a two-phase pulse (see FIG. 6) having a phase difference of 180 ° is applied. This is an example of a toner carrier that forms a two-phase electric field that repeats suction and repulsion between adjacent electrodes.

  This toner carrier 1 is provided with an A-phase electrode 111A and a B-phase electrode 111B as a plurality of electrodes 111 on the surface of an insulating substrate 101A, and a surface protective layer 101B provided thereon. The comb-shaped electrodes 111A and 111B are provided in parallel at a fine pitch in a direction orthogonal to the toner conveyance direction, and external two-phase pulse generation circuits (voltages) (not shown) are connected to both sides by common bus lines 111Aa and 111Ba. Each is connected to an application means 6).

  The pulse voltage applied to the electrodes 111A and 111B is a pulse voltage having a frequency of 0.5 KHz to 7 KHz and a DC voltage as a bias, but its peak value is ± 60 to ± 300 V, etc., depending on the electrode width and the electrode interval. Apply pulse voltage. In the case of this two-phase electric field, toner repulsion flight and suction flight are repeated according to switching of the electric field direction between adjacent ones, and the toner reciprocates between the mutual electrodes. The entire toner carrier 1 rotates and moves in the direction in which the toner is conveyed.

  As described above, the means for flying the toner on the surface of the toner carrying member to form a cloud has a plurality of electrodes arranged on the surface of the toner carrying member so as to extend in a direction perpendicular to the toner conveying direction and at predetermined intervals. The voltage applied to each electrode applies a voltage that alternately repeats the direction of attracting and repelling toner between adjacent electrodes, and the toner carrier rotates and moves, so that the toner is conveyed and clouded. With this configuration, it is possible to stably convey the toner regardless of the charge quality of the toner with respect to the toner conveyance on the surface of the toner carrier, and it is possible to realize a highly reliable image forming apparatus as a whole.

Next, another example of the toner carrier will be described with reference to FIG. FIG. 7A is a schematic plan view illustrating the toner carrying member in a developed state, and FIG. 7B is a schematic cross-sectional view illustrating the same.
This example is an example of a toner carrier that forms a three-phase traveling wave electric field. The A-phase and B-phase electrodes 111A and 111B are formed on the insulating substrate 101A, the insulating layer 101C is formed thereon, and then the C-phase electrode 111C is formed. The surface protective layer 101B is provided on the C-phase electrode 111C. ing.

  Each ABC 3-phase electrode 111A, 111B, 111C is provided in parallel at a fine pitch in a direction orthogonal to the toner transport direction, and a common bus line 111Aa, 111Ba, 111Ca is provided on both sides by an external three-phase pulse (not shown). Each is connected to a generator circuit.

  In the case of using this three-phase traveling wave electric field, as shown in FIG. 8, by sequentially applying a pulse voltage whose phase is shifted by 120 ° in one cycle, the electric field is applied to the surface of the toner carrier 101 with the switching of the pulse. However, since the traveling wave electric field that sequentially shifts is generated and the charged toner is repeatedly transported upward in the direction in which the electric field is switched, the toner carrier 101 basically remains stationary without rotating.

  As described above, the means for flying the toner on the surface of the toner carrying member to form a cloud has a plurality of electrodes arranged on the surface of the toner carrying member so as to extend in a direction perpendicular to the toner conveying direction and at predetermined intervals. In addition, by applying a phase voltage of n phase to each n electrodes and forming a traveling wave electric field between the electrodes, the toner is conveyed and clouded, so that With respect to toner conveyance, the toner conveying portion does not require rotational driving, and thus a planar belt shape is possible, and the entire apparatus can be reduced in size and cost due to the freedom of layout.

  Further, when fine particles such as an external additive of toner are deposited on the electrode surface during long-term use, the surface of the toner carrier 101 is cleaned by a cleaning mode sequence other than the image formation time. Transport reliability can be ensured. Cleaning is configured to contact the surface of the toner carrier 1 only in the cleaning mode, and cleaning is performed with a rotating brush, a blade, a suction slit, and the like. The pulse voltage applied to the electrodes 111A, 111B, and 111C is a pulse voltage having a frequency of 0.5 KHz to 7 KHz and a DC voltage as a bias, as described above, and its peak value is ± 60 to ± 300 V, etc. A pulse corresponding to the width and electrode interval is applied.

In the specific configuration of the toner carrier 1, the insulating substrate 101A as a base substrate is made of, for example, an insulating material such as resin or ceramics, or a base material made of an electrically conductive material such as aluminum. _A film formed of an insulating film such as ₂ or a film made of a flexible deformable material such as a polyimide film can be used. In addition, the electrode 111 is formed by forming a conductive material such as Al or Ni—Cr with a thickness of 0.1 to 1 μm on the base substrate and patterning it into a required electrode shape using a photolithography technique or the like. The copper foil may be formed by lamination, plating or the like and then patterned by photolithography.

As the surface protective layer 101B, for example, SiO ₂ , TiO ₂ , TiN, Ta ₂ O ₅ or the like is formed by vapor deposition with a thickness of 0.5 to ₂ μm, or an organic material such as polycarbonate, polyimide, or methyl methacrylate. May be applied by thin film printing to a thickness of 2 to 10 μm and heat-cured.

  In the toner carrying member configured as described above, a flying electric field is formed by applying a flying pulse from the driving circuit (voltage applying means 6), whereby the charged toner on the toner carrying member can have a repulsive force and / or In response to the suction force, flight in the vertical direction and transport in the traveling wave direction are performed.

  Next, the average potential Vs of the voltage with respect to the electrode 111 of the toner carrier 1, the bias voltage Vp applied to the counter electrode means (back electrode) 5, the control pulse voltage Vc applied to the control electrode 42 of the toner control means 4, and the common electrode The voltage Vg applied to 43 will be described.

  A pulse-like bias voltage having an average potential Vs (a potential at which the potential varies with time) is applied to the electrode 111 of the toner carrier 101. In this case, the peak value of the bias voltage is set according to the electrode pitch, the toner to be used, and the like. For example, it is preferable to set within a range of ± 60 to ± 300 Vpp (pp is peak-peak), and here, a voltage of ± 150 Vpp and a DC voltage component of 0 V is applied. Therefore, the DC bias on the toner carrier side 101 side with respect to the toner control unit 4 is the average potential Vs, and here, Vs = 0V. Note that the distance d between the toner carrier 1 and the toner control means 4 is 0.3 mm.

  In this example, the diameter of the toner passing hole 41 of the toner control means 4 is 100 μm, the width of the ring-shaped control electrode 42 in the center direction of the hole is 30 μm, and the interval between the control electrodes 42 and the common electrode 43 is 50 μm.

  The bias Vg to the common electrode 43 of the toner control means 4 is DC-125V, and the relationship with the bias potential Vs to the toner carrier 101 is a bias in a direction in which the toner T is always directed to the toner carrier 101 side. The toner does not adhere to the common electrode 43 surface.

  The control electrode 42 of the toner control means 4 has a control pulse voltage Vc-on of +50 V when toner T can pass through the toner passage hole 41 (ON state), except when the toner T is passed. The voltage Vc-off in the blocking state (to make it impossible to pass through) is −125V. The bias voltage Vp to the counter electrode means 5 of the recording medium means 3 depends on the interval between the toner control means 4 and the counter electrode means 5, but a DC voltage of +200 to + 1500V, for example, may be applied. Here, DC + 300V is applied with an interval of 0.3 mm between the toner control means 4 and the counter electrode means 5, and the potential gradient draws the negatively charged toner toward the counter electrode means 5 side.

  By setting the relationship between the potentials applied to the electrodes 111, 42, 43, and 5 as described above, in the state where the negatively charged toner can pass through the toner passage hole 41, the most positive side is obtained. Of the electric lines of force that emerge from the counter electrode means 5 with a high potential, most of the electric lines of force that pass through the toner passage hole 41 of the toner control means 4 pass through the toner passage hole 41 and then the common electrode 43 with the lowest potential. Will enter. At this time, since the control electrode 42 and the common electrode 43 of the toner control unit 4 located at close distances also have a potential of 175 V, strong lines of electric force are generated between them.

  Therefore, as shown in FIG. 9, when the toner T is allowed to pass through the toner passage hole 41 (ON state), the electric force lines 10 passing from the counter electrode means 5 through the toner passage hole 41 to the control electrode 42. Without entering (bypassing the control electrode 42), a large amount enters the common electrode 43 having the lowest potential of -125V, so that the loop expands. That is, the electric lines of force 10 are formed in a loop shape around the control electrode 42 between the counter electrode means 5 and the common electrode 43 of the toner control means 4.

  Accordingly, the negatively charged toner T in the cloud state on the toner carrier 101 passes through the toner passage hole 41 along the electric force lines 10, and a lot of toner T can move to the surface of the recording medium means 3. .

  At this time, + 50V is applied to the control electrode 42, and the relationship between the toner carrier 101 and 0V is the relationship in which the toner T is adsorbed to the control electrode 42. The toner should adhere to the surface of the control electrode 42, but as can be seen from FIG. 9, the electricity entering the common electrode 43 from the counter electrode means 5 through the toner passage hole 41 over the control electrode 42 to which +50 V is applied. Since the force line 10 is covered, the toner T is prevented from adhering to the control electrode 41.

  On the other hand, when the toner T is in a blocking state (OFF state) in which the toner T cannot pass through the toner passage hole 41, −125 V is applied to the control electrode 42, which is the same potential as the common electrode 43. Is a relationship that repels the toner T toward the toner carrier 101, and the toner T does not adhere to the toner control means 4, and the electric force from the counter electrode means 5 as shown in FIG. However, since there is no electric force line passing through the toner passage hole 41, the toner T does not pass through the toner passage hole 41, and a background image is not generated. Note that the voltage applied to the control electrode 42 in the blocking state (OFF state) does not have to be the same as the potential of the common electrode 43, and even if the potential is more negative, the toner T is blocked from passing (OFF state). Can).

  That is, also in this embodiment, the potential difference between the counter electrode means 5 and the toner carrier 101 is V1, the distance between the counter electrode means 5 and the toner carrier 101 is L1, and the common electrode (second electrode) 43 and the counter electrode. When the potential difference between the means 5 is V2, and the distance from the common electrode (second electrode) 43 through the control electrode (first electrode) 42 to the counter electrode means 5 is L2, V1 / L1 <V2 / A voltage that satisfies the relationship of L2 is applied to the toner carrier 101, the control electrode 41, the common electrode 43, and the counter electrode means 5, respectively.

  According to the experiment, when the relationship between the potential differences V1 and V2 and the distances L1 and L2 is V1 / L1> V2 / L2 (Comparative Example 1), electric lines of force entering the toner carrier 1 are formed as shown in FIG. As a result, no loop electric lines of force were formed, and toner adhered to the control electrode 42. In addition, in V1 / L1 = V2 / L2 (Comparative Example 2), as shown in FIG. 12, an electric force line entering the toner carrying member 1 and an electric force line going to the common electrode 43 side to some extent are formed. The loop electric lines of force were not formed, and the toner adhered to the control electrode 42.

  Thus, a toner carrier for carrying toner, a means for causing toner to fly on the toner carrier and forming a cloud, a recording medium means to which the toner is attached, and a counter electrode means for applying a voltage to the recording medium means And a toner control means having a plurality of toner passage holes disposed between the toner carrier and the recording medium means, and the toner control means has a surface around the toner passage hole and a hole inner wall on the toner carrier side surface. A control electrode for controlling the passage of toner is provided on at least one of them, a common electrode common to a plurality of toner passage holes is provided on the outside of the control electrode, and the toner passage hole of the toner control means is used as the toner of the toner carrier. When passing through the recording medium means, the control electrode is bypassed between the recording medium means side and the common electrode of the toner control means to form electric lines of force in a loop. As a result, toner adhesion to the surface of the control electrode to which the potential for attracting the toner is applied and its surroundings can be greatly reduced, and the on / off control of the passage of the toner can be stably performed, and the recording medium The lines of electric force formed between the bias potential on the means side and the common electrode outside the control electrode are larger than the diameter of the toner passage hole on the toner carrier side, and the clouded toner is captured over a wide area to the printing surface side. This makes it possible to fly toward the toner, thereby increasing the use efficiency of the toner, ensuring the printing density, and improving the printing speed.

  Further, regarding the relationship of the potential applied to each electrode, when the DC bias of the electrode 111 of the toner carrier 1 is −50 V, the pulse peak value is +150 V to −150 V, and ± 150 Vpp−50 VDC is applied, the average potential Vs is − 50V. Even when the potential Vc-on of the control electrode 42 of the toner control unit 4 when the toner passage is ON is 0 V and the potential Vc-off when the toner passage is OFF is -175 V, it is equivalent to the above-described example. In this case, since the voltage Vc applied to the control electrode 42 is ON or OFF of a unipolar voltage of 0 to -175 V, the configuration of the driver circuit is simplified, which is advantageous in terms of cost.

  Thus, by setting the relationship of the potential applied to each electrode when the toner passage is ON as described above as follows, the control electrode is bypassed between the common electrode of the counter electrode means and the toner control means. Thus, electric lines of force can be formed in a loop shape.

That is, when an average potential Vs that varies with time is applied to the electrode 111 of the toner carrying member 1 so that the toner can pass through the toner passage hole 41 with respect to the control electrode 42 of the toner control means 4. When the voltage Vc-on is set so that the toner cannot pass through the toner passage hole 41, the voltage Vc-off is applied, and the toner that has passed through the toner control means 4 is guided to the recording medium means 3 to adhere the toner. Therefore, when applying the bias voltage Vp to the counter electrode means 5,
The relationship between each potential when the toner is allowed to pass through the toner passage hole 41 is as follows.
Vp>Vc-on>Vs> Vg
In the case where the toner is negatively charged toner, the bias voltage Vp is increased to the positive potential side. In the case of the positively charged toner, the bias voltage Vp is increased to the negative potential side.

In this case, the relationship between the potentials when the toner cannot pass through the toner passage hole 41 is as follows.
Vs> Vg and Vs> Vc-off
In the case where the toner is a negatively charged toner, the average potential Vs is preferably increased to the plus potential side. In the case of the positively charged toner, the average potential Vs is preferably set to be increased to the minus potential side.

  By setting the potential relationship with respect to each of the electrodes 111, 42, 43, and 5 to the above-described relationship, the lines of electric force directly formed between the bias potential on the recording medium means side and the potential of the toner carrier are reduced, and recording is performed. An electric force can be generated between the bias potential on the medium means side and the common electrode outside the control electrode, which can greatly reduce toner adhesion to the control electrode to which the potential for attracting toner is applied and control Potential stabilizes. In addition, the lines of electric force formed between the bias potential on the recording medium means side and the common electrode outside the control electrode are wider than the diameter of the toner passage hole on the toner supply side, so that the clouded toner is captured in a wide range. This makes it possible to fly toward the printing surface side, increasing the toner utilization efficiency, ensuring the printing density, and improving the printing speed. Further, since the common electrode of the toner control unit is at a potential that always repels the toner, toner adhesion does not occur, and the common electrode potential can be kept constant, and the image forming apparatus has high reliability. Can be realized.

  Furthermore, when the amount of toner on the surface of the toner carrier 1 is increased due to high-speed printing, or when printing is performed using a toner having a large charge amount, the toner potential due to the charge of the toner cannot be ignored. Consideration must be made in determining the potential applied to each electrode.

More specifically, the change in toner potential with respect to the supplied toner amount m / Amg / cm ² on the surface of the toner carrier 1 is as shown in FIG. Here, the toner is an example of a negatively charged toner, and as the amount of toner per unit area on the surface of the toner carrier 1 increases, the surface potential viewed from the control electrode 42 side increases to a negative potential. Then, a voltage is applied to the electrode on the surface of the toner carrier 101 with respect to the potential Vo where the supplied toner is simply attached to the surface of the toner carrier 1, and the toner moves up and down along the lines of electric force between the electrodes 11. The potential Vt in the cloud state where the flight repeats greatly increases. This is because when the toner is in a space above the surface of the toner carrier 1, the coupling capacitance with respect to the periphery of the individual toner is reduced, and as a result, the potential is increased.

  The measurement of the toner potential Vt in the cloud state can be easily performed by applying a pulse voltage to each electrode 111 on the surface of the toner carrier 1 and setting the surface potential meter above the toner in the cloud state. Can be measured. Specifically, the toner control unit applies a pulse that causes clouding, rotates the toner carrier 1 while supplying toner from a one-component or two-component roller, which will be described later, or conveys the toner with a traveling wave pulse, and controls toner At a position where 4 is set, a surface electrometer is installed about 2 mm above the surface of the toner carrier 101 and measurement is performed. The results in FIG. 11 are for Vo when the charged charge amount is −15 to −25 μC / g, and when the toner potential is Vt when the toner is in a cloud state with a flying height of 200 μm from the vicinity of the surface. It is an example.

As a result of printing by performing ON / OFF control of the passage of toner by the toner control unit 4 for each supplied toner amount shown in FIG. 13, the amount of toner adhered to the surfaces of the electrodes 42 and 43 of the toner control unit 4 was evaluated. The results are shown in FIG. In the result shown in FIG. 14, in the region where the amount of supplied toner is small, the toner does not adhere to the electrodes 42 and 43. However, when the amount of supplied toner increases and 0.9 mg / cm ^2, the toner potential Vt becomes −80V. Toner adhesion to 42 begins to occur.

  This is equivalently because the potential of the toner carrier 1 is increased to the negative side and the potential difference with the common electrode 42 of the toner control means 4 is reduced, so that it comes out of the counter electrode means 5 and passes through the toner passage hole 42. This is because, among the electric lines of force, the electric lines of force directly entering the toner carrier 1 are increased, and the loop-shaped electric lines of force entering the common electrode 43 are decreased. That is, when the number of loop electric lines of force decreases, toner having high flying energy rides on the loop electric lines of force and does not fly in the direction of the printing surface, but jumps to the control electrode 42 to which the ON voltage is applied. It is to do.

Further, when the supplied toner amount increases and exceeds 1.2 mg / cm ² , the toner potential Vt becomes a value of −120 V or more. In this region, the potential difference from the bias potential Vg (−125 V) of the common electrode 43 of the toner control unit 4 disappears, and the toner having flying energy starts to reach the common electrode 43 and the toner adheres. In addition, the amount of toner attached to the control electrode 42 also increases.

  These toner adhesions are not unusable by increasing the frequency of periodic electrode cleaning, but image quality deteriorates. As long as toner adhesion does not occur, a highly reliable image recording apparatus can be achieved without decreasing image density even in continuous printing.

  Therefore, when the amount of toner is large, or when an image is formed using toner with a large amount of charged charge, the potential for each electrode is set under the following conditions to avoid toner adhesion to the electrode and use of toner High efficiency enables high-speed printing without lowering image density.

That is, when the toner potential seen from the control electrode 42 side in the cloud state where the charged toner flies from the surface of the toner carrier 1 is Vt, the relationship between the potentials when the toner passage is turned on is as follows:
Vp>Vc-on> (Vs + Vt)> Vg
In the case of negatively charged toner, Vp is increased to the positive potential side, and in the case of positively charged toner, Vp is increased to the negative potential side.

The relationship between the potentials when the toner passage is turned off is as follows:
(Vs + Vt)> Vg and (Vs + Vt)> Vc−off
In the case of negatively charged toner, the relationship is set such that (Vs + Vt) increases to the positive potential side, and in the case of positively charged toner, the relationship is set such that (Vs + Vt) increases to the negative potential side.

  The potentials for the electrodes 111, 42, 43, and 5 are set as described above. That is, the potential on the toner supply side is appropriately set in consideration of the potential due to the toner flying on the surface of the toner carrier. With this setting, even when the amount of supplied toner is high and the charged charge amount of the toner is large, the toner adhesion to the control electrode can be reduced and the toner utilization efficiency can be improved. A printing image forming apparatus can be realized.

  Further, as described above, the toner carrier has a plurality of electrodes arranged on the surface side at a predetermined interval, and alternately repeats the direction of attracting toner and the direction of repulsion between adjacent electrodes. The toner carrier is applied to the pitch P between the two phases applied to the electrodes (or the pitch between the n phases when an n phase voltage is applied to every n electrodes). The distance d between the surface and the side surface of the toner carrier of the toner control means is large.

  As a result, the loop electric field lines formed from the printing bias on the recording medium means side toward the common electrode of the toner control means are strengthened, and the clouded toner is caused to fly more toward the printing surface. This enables high-speed, high-quality dot formation.

Next, the relationship between the moving speed of the recording medium means 3 and the moving speed of the toner carrier 1 will be described.
The toner carrier 1 will be described again. For example, as shown in FIGS. 15 and 16, the electrode width is 40 μm and the inter-electrode distance is 40 μm, and the phase A of FIG. 17 is applied to the odd-numbered electrodes 111A in the toner transport direction. Similarly, the B phase is applied to the even-numbered electrodes 111B. The A-phase electrode 111A has a power supply member protruding from the left side in FIG. 16, and the B-phase electrode 111B has a power supply member protruding from the right side. The A-phase and B-phase electrodes have a comb-like electrode configuration. Yes. The end portion of the toner carrier 1 can be supplied with voltage from the outside. Such a toner carrier 1 is formed by, for example, coating a resin on a metal roller such as stainless steel as a shaft, or press-fitting a metal roller on the resin roller, and forming electrodes in a comb-teeth shape on the surface of the resin roller. It can be formed by coating with an insulating layer.

  Here, the A phase and the B phase, which are voltages applied at the normal print timing, are rectangular waves as shown in FIG. 17, and the A phase and B phase voltages are applied with a phase shift of π. Due to this phase difference, there is always a potential difference of Vpp between the A phase and the B phase. Due to this potential difference, an electric field is generated between the electrodes 111A and 111B, and the toner T hops between the electrodes 111A and 111B in accordance with the electric field to enter a cloud state.

  This potential difference Vpp is 100V to 1000V. When the potential difference Vpp is smaller than 100 V, the electric field between the electrodes becomes small, and the toner does not hop. Further, when the potential difference Vpp is larger than 1000 V, there is a risk that leakage will occur between the electrodes over time, and when the leakage occurs, an electric field will not be generated between the electrodes and the toner will not hop.

  Further, the frequency 2f at the normal print timing is 0.1 kHz to 10 kHz. When the frequency is lower than 0.1 kHz, toner hopping cannot catch up with the developing speed. When the frequency is higher than 10 kHz, the toner cannot follow the voltage switching. The central value of the voltage is varied between the image portion potential and the non-image portion potential depending on the development conditions. Although the voltage waveform to be applied is a rectangular wave, voltage switching occurs instantaneously and is suitable for toner hopping, but it may be a sine wave or a triangular wave.

  When such a toner carrier 1 is used to generate a cloud of toner T and image formation is performed, for example, when a large solid image is formed, striped unevenness may occur in the solid image. found.

  As a result of the analysis of the image unevenness phenomenon by the present inventors, the following has been found. That is, first, toner T is carried on the surface of a toner carrier 1 as shown in FIG. 16, and a cloud of toner is generated by applying A-phase and B-phase voltages to the electrodes 111A and 111B, respectively. As shown in FIG. 18, an electric field (electric field lines) 11 as shown by a broken line is formed on the toner carrier 1 by the A phase applied to the electrode 111A and the B phase applied to the electrode 111B. The The toner T on the toner carrier 1 hops between the electrodes 111A and 111B along this electric field. Therefore, the cloud-like toner of the toner carrier 1 is likely to form unevenness between the dense portion and the thin portion along the electric field shown in FIG.

  Here, FIG. 19 shows a state in which the toner carrier 1 and the recording medium means 3 are moved at a constant speed. 19 indicate the moving direction and the moving speed of the toner carrier 1 and the recording medium means 3, and the direction of the arrow shown in FIG. 19 (the right direction in the figure) is the forward direction. To do. In such a case, since the recording medium means 3 moves at the same speed as the unevenness of the cloud on the toner carrier 1, when forming a continuous solid image or the like, the toner generated by the control electric field is generated at a timing when the density of the cloud is high. It was found that when the amount of movement is large and the density of the cloud is low, the amount of toner movement due to the control electric field decreases, and solid unevenness occurs in response to the density unevenness of the cloud.

  It is known that the cloud density unevenness that causes such image unevenness tends to be improved by narrowing the distance between the electrode 111A and the electrode 111B, but the width of the electrodes 111A and 111B is too large. If it is made smaller, there are problems in terms of maintenance and management of electrode quality such as disconnection during use, and inconvenience that it cannot be made too small in terms of quality accuracy in the substrate manufacturing process by etching or the like. The mainstream in the current technology generally has a width of about 20 to 40 μm. In addition, narrowing the arrangement interval between the electrodes 111A and 111B impairs the insulating properties of the electrodes 111A and 111B. Therefore, in order not to cause damage due to voltage leakage between the electrodes 111A and 111B, the arrangement interval is reduced. There are limits to what you can do. Under these circumstances, in the configuration in which a voltage is applied to the electrodes 111A and 111B to generate a toner cloud, uneven density is a problem that cannot be completely eliminated.

  Note that in the one-component development method, which is a commonly used development method, the toner is uniformly arranged on the particle carrier by thinning the adhered toner particles by the regulating blade, so that such a development problem does not occur. . Also, in the two-component development system that is also commonly used, a medium called a carrier that carries toner by adhering to the surface has a spike-like form. However, in the actual development stage, when the carrier and the toner ear come into contact with the member to which the toner is to be moved, the toner is used in a state in which the ear is slightly asleep, so that the problem of uneven toner carrying is unlikely to occur.

  In other words, the occurrence of image unevenness due to toner cloud unevenness is a unique problem in the configuration of the toner carrier on which the electrodes are arranged and the toner cloud generation method.

  Therefore, in the image forming apparatus according to the present invention, the moving speed of the toner carrier 1 in the forward direction is different from the moving speed of the recording medium means 3 in the forward direction. Different examples of this configuration will be described with reference to FIGS.

  In the first example shown in FIG. 20, the moving speed of the toner carrier 1 in the forward direction is set to be higher than the moving speed of the recording medium means 3 in the forward direction. In this way, by making the moving speed of the toner carrier 1 relatively higher than the moving speed of the recording medium means 3, the apparent cloud density unevenness seen from the recording medium means 3 per unit time is reduced. Thus, image unevenness is reduced.

  In the second example shown in FIG. 21, the moving speed of the toner carrier 1 is set in the minus direction (reverse direction) with respect to the moving speed of the recording medium means 3. In this way, the moving direction of the toner carrier 1 is opposite to the moving direction of the recording medium means 3, and the moving speed in the forward direction of the toner carrier 1 and the moving speed in the forward direction of the recording medium means 3 are set. By making them different, the apparent cloud density unevenness seen from the recording medium means 3 per unit time is reduced, and the image unevenness is reduced.

  In the configuration of the second example, it is only necessary that the rotation direction (toner transport direction) of the toner carrier 1 is opposite to the moving direction of the recording medium means 3, and the same effect as the configuration of the first example is obtained. 1 can be achieved in a state where the absolute speed is small, and the life of the member (part) can be extended.

Here, the pulse width (time) of the bias Vc applied to the control electrode 42 is determined by the moving speed of the recording medium means 3 and the resolution of the image. For example, when the recording medium means 3 is moving at 100 mm / sec and an image is formed with a resolution of 600 dpi, the maximum pulse width of the bias applied to the control electrode 42 is
(25.4 ÷ 600) ÷ 100 = 0.0004233 [sec]
It becomes. That is, it is about 0.42 msec. FIG. 22 shows a summary of the maximum pulse widths applied to the control electrode 42 determined by the moving speed and resolution of the recording medium means 20 as described above.

23, when the distance between the electrode 111A and the electrode 111B of the toner carrier 1 is x, the speed of the toner carrier 1 in the present invention is equal to or greater than the distance x in the pulse width (time) shown in FIG. It is preferable to set to move. For example, when forming an image with a resolution of 600 dpi when the distance between the electrode 111A and the electrode 111B is 0.080 mm (80 μm) and the recording medium means 3 is moving at 100 mm / sec,
0.080 ÷ 0.0004233 = 188.99 [mm / sec]
It becomes. Therefore, the moving speed of the toner carrier 1 is preferably higher than about 189 mm / sec.

  In this way, the peak portion of the cloud-like toner (high toner density) and the valley portion (low toner density) pass through the toner passage hole 41 of the toner control means 4 within the pulse time. Compared with the case where only a mountain-shaped portion or a valley-shaped portion passes through, unevenness of an image can be made less likely to occur.

Next, the relationship with the arrangement example of the toner passage holes 41 on the FPC when the toner control means 4 is formed by FPC will be described with reference to FIG.
In this example, in the FPC 4A as the toner control means 4 shown in FIG. 24A, toner passing holes 41 through which the toner T passes are formed in an eight-row staggered arrangement as shown in FIG. The toner passage holes 41 are in the first row, the second row,. The recording medium means 3 moves from left to right in the figure.

  In this way, in the configuration in which the toner passage holes 41 are arranged in a plurality of rows with respect to the moving direction of the recording medium means 3, when the toner carrier 1 and the recording medium means 3 have the same speed, the toner carrier 1 to the recording medium means When the amount of toner flying to 3 is large, the toner on the toner carrier 1 is consumed in order from the first row of the toner passage holes 41, and therefore the first row of toner passage holes 41 and the eighth row of toner are consumed. The supply amount of toner changes in the passage hole 41. In order to avoid such a phenomenon, it is effective to move the toner carrier 1 faster than the recording medium means 3 as in the present invention.

  For example, it is possible to reduce image unevenness by making the moving speed of the toner carrier 1 slower than the moving speed of the recording medium means 3. However, the frequency of occurrence of image unevenness (for example, the number of image unevenness (streaks) included in a solid image when all solid images are formed) is reduced. Compared to the first example in which the moving speed is higher than the moving speed of the recording medium means 3. Further, when the toner moving speed from the toner carrier 1 to the recording medium means 3 is high, in the arrangement of the toner passing holes shown in FIG. 24, the toner passing holes on the upstream side and the downstream side in the moving direction of the recording medium means 3 In some cases, the density of particles on the toner carrier 1 is different in the toner passage hole.

  In the above embodiment, the toner control means is described as having a first electrode (control electrode) and a second electrode (common electrode). However, as shown in FIG. Further, the present invention can be similarly applied to an image forming apparatus having only the toner passage hole 41 and the control electrode 42.

  Further, the present invention can be applied to an image forming apparatus using either positively charged toner or negatively charged toner as the toner. Further, the shape of the toner carrier, toner control means, counter electrode means, etc. is not particularly limited, such as a roller shape, a plate shape, or a substrate shape.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 26 is a schematic configuration diagram of the image forming apparatus according to the embodiment.
In this image forming apparatus, four units of the first embodiment described above are provided, and toner for four colors of yellow (Y), magenta (M), cyan (C), and black (K) is clouded and toner control is performed. 1 is an example of an image forming apparatus that forms an image by performing ON / OFF control by means.

  That is, this image forming apparatus supplies toner for four colors of yellow (Y), magenta (M), cyan (C), and black (K) along the intermediate transfer recording medium 103 which is a recording medium means. Four toner supply units 100y, 101m, 101c, and 101k (referred to as “toner supply unit 100” when colors are not distinguished. The same applies hereinafter) are arranged between each toner supply unit 100 and the intermediate transfer recording member 103. In addition, toner control means 4 similar to those in the first embodiment are arranged.

  As in the first embodiment, the toner supply unit 100 includes a toner carrier 1 that rotates in the direction indicated by an arrow in which a plurality of electrodes 111 that apply a voltage are arranged in order to make the toner cloud, and the toner carrier 1 And a rotating toner supply roller 113 for supplying toner and a blade 114 for regulating the amount of toner on the toner carrier 101.

  In the toner supply unit 100, toner is supplied to the toner carrier 1 from the toner supply roller 113, and frictional charging of the toner is performed by friction between the toner on the toner supply roller 113 and the toner carrier 1. The blade 114 on the downstream side of the toner replenishing roller 113 keeps the toner amount on the surface of the toner carrying member 1 to be a constant amount with a thin layer and stabilizes the toner charge amount.

  Further, the intermediate transfer recording member 103 is looped around the two rollers 132 and 133 and moves in the direction indicated by the arrow. On the back surface (inside) of the intermediate transfer recording body 103, a back electrode 5, which is a counter electrode means (recording medium means side electrode), is disposed corresponding to each toner supply unit 100. Further, a cleaning unit 135 for removing residual toner on the intermediate transfer recording body 103 after the transfer is provided.

  Here, as described in the first embodiment, the moving speed of the toner carrier 1 of the toner supply unit 100 is set to be higher than the moving speed of the intermediate transfer recording body 103. The moving direction of the toner carrier 1 may be opposite to the moving direction of the intermediate transfer recording member 103.

  Then, the toner supplied by the toner supply unit 100 is turned on / off according to the image by the toner control unit 4 to fly on the intermediate transfer recording body 103, and color toner on the intermediate transfer recording body 103. An image is formed.

  On the other hand, a paper feeding unit 105 that accommodates the recording paper 150 is disposed below. The recording paper 150 is fed from the paper feeding unit 105 by a pickup roller (paper feeding roller) 106 and is wound around the intermediate transfer recording body 103. The toner image on the intermediate transfer recording body 103 is transferred by the transfer roller 107 disposed opposite to the roller 132, and the toner is melted and fixed on the recording paper 150 by the fixing unit 108 and discharged.

  Although not shown here, the toner image is transferred from the intermediate transfer recording body 103 to the surface of the recording paper 150 by applying a + bias to the transfer roller 107 on the back side of the recording paper 150. Further, as described above, the intermediate transfer recording member 103 is cleaned with the remaining toner by the cleaning unit 135, and the next image formation is performed.

  As described above, this image forming apparatus is an intermediate transfer recording method in which a four-color image is formed on an intermediate transfer recording body and then transferred to a recording sheet supplied from a paper feeding unit. In the case of this intermediate transfer recording method, it is easy to ensure the accuracy of maintaining a constant distance between the printing surface (the surface on which toner is landed, also referred to as an image forming surface) and the toner control means, and the toner flying speed is low. Can improve image quality. In addition, an image forming apparatus that prints directly with ON / OFF of the passage of the clouded toner can obtain a printing surface that is smooth and does not accumulate charges by adjusting the volume resistivity, and has no potential fluctuation, and has high sensitivity to potential, Although image quality fluctuations are likely to occur with respect to fluctuations in the printing surface bias potential, this configuration makes it possible to obtain a reliable and high-quality color image.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 27 is a schematic configuration diagram of the image forming apparatus according to the embodiment.
This image forming apparatus is an example in which an image is directly formed on a recording sheet using a recording medium means as a recording sheet. That is, here, the recording paper 150 supplied from the paper supply unit 105 is electrostatically attracted to the paper transport belt 161 and passed through the area of the toner supply unit 100, and ON / OFF corresponding to the image of the toner control unit 4. A color image is directly formed on the recording paper 150 by the OFF control.

  The paper transport belt 161 is formed of polyimide or the like, is wound around two rollers 162 and 163, moves around in the direction of the arrow, and is charged by a charging unit such as a charging roller (not shown), thereby being recorded on the recording paper 150. Are electrostatically attracted and transported. A guide 164 and a registration roller 165 for guiding the recording paper 150 from the paper supply unit 105 to the paper transport belt 161 are also arranged.

  Here, the moving direction of the toner carrier 1 of the toner supply unit 100 is opposite to the moving direction of the recording paper 150 by the paper conveyance belt 161, but the moving direction of the toner carrier 1 is recorded by the paper conveyance belt 161. It is also possible to set the moving speed of the toner carrier 1 of the toner supply unit 100 to a speed higher than the moving speed of the recording paper 150 with the moving direction of the paper 150 as the same direction.

  In this configuration, there is a paper transport belt 161 such as polyimide and the recording paper 150 between the toner control means 4 for controlling the toner passage and the counter electrode means 5 for applying a bias for guiding the toner after the passage to the recording paper 150. Therefore, it is difficult to set the distance between the toner control unit 4 and the counter electrode unit 5 very narrow, but on the other hand, since a color image is directly formed on the recording paper 150 and there is no transfer process, the image quality is reduced by toner scattering due to transfer. It will not drop.

  In addition, the belt cleaning mechanism as in the configuration of the second embodiment is not necessary, which is advantageous for realizing a small-sized and low-cost image forming apparatus. In this configuration where the toner is made into a cloud, it is possible to guide the toner by setting the printing surface bias low, so that the landing speed of the toner on the paper surface can also be set low, and a high quality image that does not cause toner scattering. A forming device can be obtained.

Next, an example of a specific configuration of the toner supply unit 100 in the image forming apparatus according to the second and third embodiments will be described with reference to FIG.
This toner supply unit 100 is an example in which a two-component recording material comprising a magnetic carrier and a non-magnetic toner is used. The recording agent storage unit 201 is divided into two chambers 201 </ b> A and 201 </ b> B and is connected by recording agent passages (not shown) at both ends in the toner supply unit 100. The recording agent storage unit 201 stores a two-component recording agent and is transported through the recording agent storage unit 201 while being stirred by the stirring transport screws 202A and 202B in the chambers 201A and 201B.

  A toner supply port 203 is disposed in the chamber 201 </ b> A of the recording agent storage unit 201, and is supplied into the recording agent storage unit 201 from a toner storage unit (not shown) through the toner supply port 203. The recording agent storage unit 201 is provided with a toner concentration sensor (not shown) that detects the magnetic permeability of the recording agent, and detects the concentration of the recording agent. When the toner concentration in the recording agent storage unit 201 decreases, toner is supplied into the recording agent storage unit 201 from the toner supply port 203.

  A magnet brush 204 as a toner replenishing roller is disposed at a position facing the agitating and conveying screw 202B. A fixed magnet is disposed inside the mag brush roller 204, and the recording agent in the recording agent storage unit 201 is pumped up to the surface of the mag brush roller 204 by the rotation and magnetic force of the mag brush roller 204. A recording material layer regulating member 205 is provided at a position facing the mag brush roller 204 upstream of the recording material pumping position in the rotational direction of the mag brush roller 204.

  The recording agent pumped up at the pumping position is regulated to a certain amount of recording agent layer by the recording agent layer regulating member 205. The recording agent that has passed through the recording agent layer regulating member 205 is conveyed to a position facing the toner carrier 1 as the magnetic brush roller 204 rotates. A supply bias is applied to the magnet brush roller 204 by the first voltage applying means 211.

  In the toner carrier 1, a required pulse voltage is applied to the electrode 111 by the second voltage applying unit 212. At a position facing the mag brush roller 204, an electric field is generated between the toner carrier 1 and the mag brush roller 204 by the first and second voltage applying means 211 and 212. Under the electrostatic force from the electric field, the toner is separated from the carrier and moves to the surface of the toner carrier 1. The toner that has reached the surface of the toner carrier 1 is clouded by the electric field generated by the voltage applied from the second voltage application means 212 to the electrode 111, and the toner carrier 1 rotates or travels by the electrode 111 of the toner carrier 1. Carried by a wave electric field.

  Then, the toner conveyed to a position facing the toner control means 4 is selectively jumped to the recording medium means side by the control electric field of toner control ON / OFF of the control electrode 42 to control dot printing of the toner. The

Next, another example of the specific configuration of the toner supply unit 100 in the image forming apparatuses according to the second and third embodiments will be described with reference to FIG.
The toner supply unit 100 is an example using a one-component recording material made of non-magnetic toner. The toner is stored in the recording material storage unit 201. The toner is frictionally charged with the toner supply roller 113 by the charging roller 220, and is pumped up onto the toner supply roller 113 by electrostatic force. The toner on the toner supply roller 113 is made into a thin layer by the recording material layer regulating member 114 and is conveyed to a position facing the toner carrier 1 as the toner supply roller 113 rotates.

  At this time, a supply bias is applied to the toner supply roller 113 by the first voltage application unit 221. A voltage is applied to the electrode 111 by the second voltage applying means 222 in the toner carrier 101. Therefore, at a position facing the toner carrier 1, an electric field is generated between the toner carrier 1 and the toner supply roller 113 by the first and second voltage applying means 221 and 222, and an electrostatic force is received from the electric field. The toner is separated from the toner supply roller 113 and moved to the surface of the toner carrier 1.

  Similar to the above example, the toner that has reached the surface of the toner carrier 1 is clouded by the electric field formed by the voltage applied to the electrode 111 from the second voltage applying means 222, and the rotation of the toner carrier 1 or the toner carrier It is carried by the traveling wave electric field by the electrode 111 of the body 1.

  Then, the toner conveyed to a position facing the toner control means 4 is selectively jumped to the recording medium means side by the control electric field of toner control ON / OFF of the control electrode 42 to control dot printing of the toner. The

  In each of these toner supply units 100, the toner that has not contributed to the printing is further conveyed by the toner carrier 1 and is collected from the surface of the toner carrier 1 by a collecting means (not shown). The collected toner is returned again to the recording material container 201 and circulates in the toner supply unit 100.

It is a typical lineblock diagram showing an example of a 1st embodiment of the present invention. It is explanatory drawing which shows an example of the control pulse similarly applied to a control electrode. (A) is an explanatory view on the printing surface side showing an example of toner control means, and (b) is an explanatory view on the toner supply side surface. (A) is an explanatory view on the printing surface side showing another example of the toner control means, and (b) is an explanatory view of the toner supply side surface. (A) is a schematic plan view showing an example of a toner carrier, and (b) is a schematic cross-sectional view. FIG. 4 is an explanatory diagram illustrating an example of a pulse voltage applied to an electrode of the toner carrier. (A) is a schematic plan view showing another example of the toner carrier, and (b) is a schematic cross-sectional view. FIG. 4 is an explanatory diagram illustrating an example of a pulse voltage applied to an electrode of the toner carrier. FIG. 7 is an explanatory diagram showing electric lines of force that pass through a toner passage hole based on a simulation result of a two-dimensional cross-sectional electric field intensity distribution when the toner control unit is in a state where toner can be passed. FIG. 7 is an explanatory diagram showing electric lines of force when toner is not allowed to pass through. It is explanatory drawing which shows the electric force line similar to FIG. 8 in the case of the comparative example 1. FIG. 9 is an explanatory diagram showing electric lines of force similar to FIG. 8 in the case of Comparative Example 2. FIG. 6 is an explanatory diagram illustrating an example of a relationship between a supplied toner amount and a toner potential. FIG. 7 is an explanatory diagram for explaining a relationship between a supplied toner amount and toner adhesion to a toner control unit. FIG. 3 is a schematic explanatory diagram of a toner carrier used for explaining a relationship between a toner carrier and a moving speed of a recording medium unit. FIG. 4 is a schematic explanatory view showing the toner carrier in a developed state. It is explanatory drawing of the voltage waveform similarly applied to the electrode of a toner carrier. FIG. 6 is a schematic explanatory view for explaining the relationship between the clouding of toner on the toner carrier and the lines of electric force. FIG. 6 is a schematic explanatory diagram for explaining the occurrence of image unevenness due to toner cloud unevenness on the toner carrier. FIG. 6 is a schematic explanatory diagram for explaining a first example in which the moving speeds of the toner carrier and the recording medium unit are similarly varied. FIG. 6 is a schematic explanatory view for explaining a second example in which the moving speeds of the toner carrier and the recording medium unit are similarly varied. It is explanatory drawing which shows an example of the relationship between the maximum pulse width of the voltage pulse applied to a control electrode, the moving speed of a recording medium means, and image resolution. FIG. 4 is an explanatory diagram for explaining a distance between electrodes of a toner carrier. FIG. 4 is an explanatory diagram for explaining an arrangement example of toner passage holes and a moving speed of a toner carrier when configured by an FPC of a toner control unit. It is a block diagram which shows the other example of 1st Embodiment of this invention. It is a typical explanatory view showing an image forming apparatus concerning a 2nd embodiment of the present invention. It is a typical explanatory view showing an image forming apparatus concerning a 3rd embodiment of the present invention. FIG. 3 is a schematic explanatory diagram illustrating an example of a toner supply unit. FIG. 6 is a schematic explanatory diagram illustrating another example of a toner supply unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Toner carrier 3 ... Recording medium means 4 ... Toner control means 5 ... Counter electrode means 41 ... Toner passage hole 42 ... Control electrode 43 ... Common electrode 100 ... Toner supply unit 103 ... Intermediate transfer recording body 104 ... Toner control means 111 ... Electrode 150 ... Recording paper

Claims (5)

A toner carrier that carries a charged toner and moves in a predetermined movement direction, and has a plurality of electrodes provided on the surface at predetermined intervals in the movement direction;
Clouding means for alternately applying a voltage in the direction of attracting and repelling the toner to a plurality of electrodes of the toner carrier;
A recording medium means to which the toner is attached;
A toner control means having a plurality of toner passage openings disposed between the toner carrier and the recording medium means;
Counter electrode means for applying a voltage to the recording medium means side;
A first electrode provided in the toner control means for controlling the flying of the toner from the toner carrier;
A second electrode provided on a surface of the toner control unit facing the toner carrier and distant from the first electrode;
The potential difference between the counter electrode means and the toner carrier is V1, the distance between the counter electrode means and the toner carrier is L1, the potential difference between the second electrode and the counter electrode means is V2, the second When the distance from the electrode through the first electrode to the counter electrode means is L2,
V1 / L1 <V2 / L2
Voltage application means for applying a voltage satisfying the relationship to the toner carrier, the first electrode, the second electrode, and the counter electrode means,
2. An image forming apparatus according to claim 1, wherein when the moving direction of the recording medium means is a forward direction, the moving speed of the toner carrier in the forward direction is different from the moving speed of the recording medium means in the forward direction.   2. The image forming apparatus according to claim 1, wherein the moving speed of the toner carrier in the forward direction is faster than the moving speed of the recording medium means in the forward direction.   3. The image forming apparatus according to claim 1, wherein a voltage applied to the electrode of the toner carrying member is Vs, a voltage applied to the counter electrode unit is Vp, and a voltage applied to the first electrode of the toner control unit. Is Vc, and the voltage applied to the second electrode of the toner control means is Vg. When the toner is allowed to pass through the toner passage opening, the charge polarity of the toner is opposite to , Vp> Vc> Vs> Vg.   4. The image forming apparatus according to claim 3, wherein when the toner is prevented from passing through the toner passage opening, a voltage having a relationship of Vc <Vg is applied to the first electrode and the second electrode. An image forming apparatus.   5. The image forming apparatus according to claim 4, wherein a relationship of Vs> Vt> Vg is established when the potential of the toner is Vt.

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