JP2009083461A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that in formation of an image by a direct recording system, toner sticks to the surface of a toner control means and the periphery of a toner passage hole, consequently, it is impossible to stably perform an ON/OFF control of toner-passage. <P>SOLUTION: When a voltage difference between a counter electrode means 31 and a toner carrier 101 is expressed by V1, a distance between the counter electrode means 31 and the toner carrier 101 is expressed by L1, a voltage difference between a common electrode (second electrode) 43 and the counter electrode means 31 is expressed by V2, and a distance from the common electrode (second electrode) 43 to the counter electrode means 31 via a control electrode (first electrode) 42 is expressed by L2, a voltage establishing a relation of VL/L1<V2/L2 is separately applied to the toner carrier 101, the control electrode 41, the common electrode 43 and the counter electrode means 31. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image formed by flying and adhering toner ejected from a toner carrier to a recording medium means through a toner passage opening (also referred to as a toner passage hole or opening) that is controlled to open and close. 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 such a direct recording type image forming method, a voltage is applied to the flight control electrodes provided around the holes and slits, and an electric field is applied to the charged layer of image forming particles (toner) and the toner cloud. Or a toner image at a specific position corresponding to the slit is selectively ejected, and the aggregate is moved through a hole or a slit to be attached to a recording member such as paper. The minimum unit image formed by an aggregate of image forming particles is directly formed on the surface of the recording member. In the present application, “toner” is a generic term for what can be given an image on a recording medium (recording member), 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. Are listed.

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. The control electrode surrounding the aperture and the printing surface side are paired with each other. 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. Further, this Patent Document 7 also describes a configuration in which a guard electrode is provided outside the control electrode to prevent toner from adhering to portions other than the control electrode.
JP 11-301014 A

  A basic configuration for forming an image by a conventional direct recording method is configured as shown in FIG. 22, for example. In FIG. 22, a toner carrying roller 501 as an agent carrying member is arranged so that its axis extends in the left-right direction in the figure, and is rotated by a driving means (not shown) while charging the charged toner T. Supported on the surface. Under the toner carrying roller 501, a flexible printed circuit board 503 is provided as a hole forming member for forming a plurality of holes 502. The FPC 503 includes a plurality of ring-shaped flying electrodes 504 formed on the side facing the toner carrying roller 501 so as to surround each hole 502.

  Under the FPC 503, a counter electrode 506 that faces the toner carrying roller 501 through the FPC 503, and a recording paper 507 that is transported by the transport unit on the counter electrode 506 are disposed. In FIG. 16, only one hole 502 and one flying electrode 504 are shown for convenience, but a plurality of these combinations are actually formed in the FPC 503. Specifically, for example, in the 600 dpi FPC 503, 4960 combinations of these are formed.

  Therefore, the toner carrying roller 501 carries, for example, the toner T charged to the negative polarity on the surface in a grounded state. When a flying voltage having a positive polarity is applied to the flying electrode 504, an electric field having a predetermined intensity acts on the toner T at the position facing the flying electrode 504 on the toner carrying roller 501 and the toner T in the vicinity thereof. . Due to the action of the electric field, the electrostatic force applied to the toner T exceeds the adhesive force between the toner T and the toner carrying roller 501, and the aggregate of the toner T selectively flies from the toner carrying roller 501 in a dot shape. Enter the hole 502.

  Then, it continues to fly by being attracted by an electric field formed between the flying electrode 504 and the counter electrode 506 having a higher potential, and passes through the hole 502 and adheres to the surface of the recording paper 507. To do. Due to this adhesion, the aggregate of the toner T becomes a dot image.

  In this case, ON / OFF of the flying voltage for each flying electrode 504 needs to be individually controlled by a dedicated IC. That is, in the direct recording type image forming apparatus, when the voltage is high, the same number of expensive ICs as the flying electrodes 504 are required. For example, when an FPC 3 for 600 dpi is used, 4960 expensive switching elements need to be provided. In general, an IC is expensive because it requires a chip area as its withstand voltage increases. In a direct recording type image forming apparatus, how to lower the control voltage is important for reducing the cost of the apparatus. It becomes an element.

  However, the toner T and the toner carrying roller 501 have adhesion forces that attract each other by mirror image force, van der Waals force, liquid bridging force, and the like, which hinders the reduction of the flying voltage. . As a result, it is necessary to apply a flying voltage of at least 500 V or more in the apparatus shown in FIG.

  On the other hand, the developer carrying member as described in Patent Document 4 has a plurality of electrodes, and an electric field that changes with time is formed between the electrodes to cloud the toner, and the toner is used as a control electrode. By adopting the configuration of flying to the side, the voltage applied to the flying electrode can be lowered.

  However, since a strong electric field is generated between the plurality of fine pitch electrodes provided on the developer carrying member to generate a strong electric field, the flying toner adheres to the surface of the control electrode, and the toner There is a problem that the accumulation and adhesion also occur around the hole through which the toner passes, and the passage amount of the toner varies with time, and the image density is likely to vary.

  In addition, the toner in the cloud state that flies on the surface of the developer carrying member is distributed in the height direction, and simply applying a control pulse to the control electrode results in poor use efficiency of the toner passing through the toner passage opening, and printing. It is difficult to secure speed. Furthermore, the adhesion of toner in the cloud state not only adheres to the control electrode that is used continuously in a stationary state, but also proceeds to adhere and accumulate on its peripheral members. As a result, the potential of the entire member on which the control electrode is formed is increased. Rises to a potential in a direction corresponding to the charging polarity of the toner, acts as a reverse bias electric field for the toner flying from the surface of the developer carrying member, and the flying efficiency is lowered.

  The present invention has been made in view of the above problems, and can reduce the adhesion of toner to the surface of the toner control means and the vicinity of the toner passage opening, and stably control the on / off of the toner passage. It is possible to improve the toner utilization efficiency.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A toner carrier for carrying toner, and 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; a counter electrode means for applying a voltage to the recording medium means side;
A first electrode provided on the toner carrying opening side surface of the toner control means on the toner passage opening side and a second electrode provided at a position away 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, and the second electrode to the first electrode are When the distance to the counter electrode means via L2 is,
The potential difference V1 is 300 to 1500 V, the potential difference V2 is 800 to 2000 V, the distance L1 is 275 to 1000 μm, the distance L2 is 425 to 850 μm, and the relationship V1 / L1 <V2 / L2 holds.
A voltage application unit for applying a voltage to the toner carrier, the first electrode, the second electrode, and the counter electrode unit is provided.

  Here, when the toner is negatively charged toner, the voltage Vp applied to the counter electrode means is increased to the positive potential side. When the toner is positively charged toner, the voltage Vp applied to the counter electrode means is increased to the negative potential side. It can be set as the structure which becomes.

The relationship between the potentials when the toner cannot pass through the toner passage opening is as follows: the average potential of the voltage applied to the toner carrier is Vs, the voltage applied to the second electrode is Vg, When the voltage applied to the electrode is Vc-off,
Vs> Vg and Vs> Vc-off
Thus, when the toner is a negatively charged toner, the average potential Vs is increased to the positive potential side, and when the toner is a positively charged toner, the average potential Vs is increased to the negative potential side.

  In this case, when the potential of the toner layer on the toner carrier is Vt, the relationship is Vs> Vt> Vg when the toner is negatively charged toner, and Vs <Vt when the toner is positively charged toner. <Vg can be established.

  In addition, the toner carrier can be configured to carry the toner in the form of a cloud, and the toner exists between the electric lines of force formed between the second electrode and the counter electrode means and the toner control means.

  In this case, the toner carrier has a plurality of electrodes arranged at a predetermined interval on the surface side, and a voltage having a relationship of alternately repeating the direction of attracting and repelling toner between adjacent electrodes is applied. The toner carrier surface and the toner of the toner control means with respect to the pitch between the two-phase electrodes applied to the electrodes or the pitch between the n-phase electrodes when the n-phase voltage is applied to each n-th electrode. It can be set as the structure where the distance between a support body side is large.

  Further, the recording medium means can be a recording paper, and the counter electrode means provided on the back surface of the recording paper can be arranged.

  The recording medium means may be an intermediate transfer medium, and the intermediate transfer medium itself may also serve as the counter electrode means, or the counter electrode means may be provided on the back surface of the intermediate transfer medium.

  Further, a color image can be formed on the recording medium means by superposing different color toners.

  In addition, when the toner passage opening of the toner control means is in a state where the toner on the toner carrier can pass toward the recording medium means, the first electrode is provided between the recording medium means side and the second electrode of the toner control means. An electric force line may be formed in a loop shape around the electrode.

  Moreover, it can be set as the structure provided with the insulating layer which covers a 1st electrode. In this case, the insulating layer covering the first electrode can be formed of a resin material and has a thickness in the range of 2 to 20 μm.

  According to the image forming apparatus of the present invention, the voltage between the counter electrode unit and the toner carrier is V1, the distance between the counter electrode unit and the toner carrier is L1, and the voltage between the second electrode and the counter electrode unit is V2. When the distance between the second electrode and the first electrode and the counter electrode is L2, the potential difference V1 is 300 to 1500 V, the potential difference V2 is 800 to 2000 V, the distance L1 is 275 to 1000 μm, and the distance L2 is 425 to 850 μm. In addition, since the voltage satisfying the relationship of V1 / L1 <V2 / L2 is applied to the toner carrier, the first electrode, the second electrode, and the counter electrode unit, the toner control unit is provided. When the toner on the toner carrying member is allowed to pass toward the recording medium means, the first electrode for controlling the passage of the toner is bypassed between the recording medium means side and the second electrode of the toner control means. Electric force lines are formed in the shape of a toner, and toner adhesion on the surface of the toner control means and around the toner passage opening is reduced, so that on / off control of toner passage can be performed stably and the use of toner Increase efficiency.

Embodiments of the present invention will be described below with reference to the accompanying drawings. An embodiment of the present invention will be described with reference to a schematic configuration diagram of FIG. 1 and a perspective view of relevant parts in FIG.
In this embodiment, a roller-like toner carrier 1 carrying toner T, a recording medium means 3 to which the toner T is adhered, and a plurality of media disposed between the toner carrier 1 and the recording medium means 3. And a toner control means 4 having a toner passage hole 41 which is a toner passage opening.

  The toner carrier 1 is disposed inside a toner container 13 that contains the toner T, and the toner T that is frictionally charged negatively by friction between a toner supply member (not shown) and the toner carrier 1 is surfaced with electrostatic force. The toner layer is formed by being carried on and regulated by the doctor blade 14. A bias voltage Vs (here, Vs = ground potential) is applied to the toner carrier 1.

  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. 3 is applied to the control electrode 42 of the toner control means 4 from a control pulse generating means 6 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 7 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.

  Note that the control electrode 42 as the first electrode is preferably covered with an insulating layer. Examples of the insulating layer include resin materials such as PI, PA, urethane, acrylic, melanin, alkyd, Teflon (registered trademark), and fluororesin. The thickness of this insulating layer is preferably in the range of 2 to 20 μm. If the thickness is less than 2 μm, the insulation performance is poor, and if it exceeds 20 μm, the formation of the electric field becomes insufficient.

  The insulating layer may be composed of, for example, PI and Teflon (registered trademark), and the insulating property and toner adhesion prevention may be functionally separated. Further, both the control electrode 42 that is the first electrode and the common electrode 43 that is the second electrode may be covered with an insulating layer.

  By covering the control electrode 42 with the insulating layer in this way, it is possible to reduce the adhesion of toner to the control electrode, and the insulation between the first and second electrodes (control electrode-common electrode) is maintained, and long-term Stable image quality can be obtained.

  A back electrode 31 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 the bias power supply means 8 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. For the application of the bias voltage Vp to the recording medium means 3, for example, a back electrode 31 is disposed on the back side of the recording medium means 3 (the side opposite to the toner carrier 1), and the recording medium means 3 passes above the back electrode 31. In the case of an intermediate transfer recording medium, a configuration in which a counter electrode means is embedded inside or a back electrode 31 is disposed on the back surface of the intermediate transfer recording medium can be adopted.

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 is determined by the size of the dot diameter to be formed, and has a diameter of φ30 μm to φ150 μm. 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, the voltage Vs applied to the toner carrier 1, the voltage Vp applied to the counter electrode means (back electrode) 31, the voltage Vc applied to the control electrode 42 of the toner control means 4, and the voltage Vg applied to the common electrode 43. The relationship will be described with reference to FIG.
Here, when the voltage Vs is applied to the toner carrier 1, the voltage Vp is applied to the counter electrode means (back electrode) 31, the voltage Vc is applied to the control electrode 42 of the toner control means 4, and the voltage Vg is applied to the common electrode 43, the counter electrode means. The potential difference between the (back electrode) 31 and the toner carrier 1 is controlled by V1, the distance between the counter electrode means 31 and the toner carrier 1 is L1, the potential difference between the common electrode 43 and the counter electrode means 31 is controlled by V2, and the common electrode 43 is controlled. When the distance from the electrode 42 to the counter electrode means 31 is L2 (see FIG. 1), each voltage is applied so that the relationship V1 / L1 <V2 / L2 is established.

  For example, when negatively charged toner is used, the toner carrier 1 is grounded, a DC high voltage Vp of +300 V is applied to the counter electrode means 31, and a control pulse that is ON / OFF controlled based on an image signal to the control electrode 42. Vc (Vc-on = + 50, Vc-off = −125 V), and a voltage Vg of −125 V is applied to the common electrode 43. The application time of the ON state voltage Vc-on of the control pulse Vc is 210 [μsec], the peripheral speed of the image carrier 1 is 300 [mm / sec], and the conveying speed of the recording medium means 3 is 100 [mm / sec]. sec]. The charge amount of the toner is −30 to −20 μC / g, and the volume average diameter of the toner is 6.2 μm.

  Thereby, in the toner passage hole 41 where the voltage Vc-on (+50 V) is applied to the control electrode 42, as shown in FIG. 6A, the control electrode of the toner control means 4 from the counter electrode means 31 side. A loop electric field line 10 that bypasses 42 and enters the common electrode 43 is formed, and an electric field acts on the toner T having a negative charge on the toner carrier 1, and as a result of this action, the loop is applied to the toner T. The coulomb force exceeds the sum of the adhesion force and the mirror image force acting between the toner T and the toner carrier 1, and the aggregate of the toner T is induced to the loop electric lines of force 10, and the counter electrode means 31. And passes through the center of the toner passage hole 41 without adhering to the control electrode 42.

  The aggregate of the toner T that has passed through the toner passage hole 41 is attracted by the flying electric field formed by the voltage Vp applied to the counter electrode means 31 and continues to fly, and is transported on the counter electrode means 31 by a transport means (non-conductive). As shown in the figure, it adheres to the recording medium means 3 conveyed in a predetermined direction and finishes flying.

  On the other hand, at the portion of the toner passage hole 41 where the voltage Vc-off is applied to the control electrode 42, as shown in FIG. 6B, the electricity entering the control electrode 42 of the toner control means 4 from the counter electrode means 31 side. A line of force is formed, and the toner T cannot pass through the toner passage hole 41.

Here, an example of an experimental result for different electric field conditions will be described with reference to FIG.
A voltage Vc-on (= + 50 V) is applied to the control electrode 42 of the toner control means 41, the voltage Vp of the counter electrode means 31, the voltage Vs of the toner carrier 1, the voltage Vg of the common electrode 43, the distances L1, L2, and the toner. The adhesion of the toner to the control electrode 42 of the toner control means 41 when the thickness of the FPC forming the control means 4 is changed as shown in the column of Example, Comparative Example 1 and Comparative Example 2 shown in FIG. The situation was observed.

  7B shows the voltages Vp, Vs, Vg, the potential difference V1 (V1 = potential difference between Vp and Vs), the potential difference V2 (V2 = potential difference between Vp and Vg), and the distances shown in FIG. 7A. L1 and L2 are extracted. FIG. 7C shows the relationship between the potential difference V1, the distance L1, and the result V1 / L1, and the potential difference V2, the distance L2, and the result V2 / L2.

  As a result, when the relationship between the potential differences V1 and V2 and the distances L1 and L2 is V1 / L1 <V2 / L2 (Example), the loop electric lines of force shown in FIG. No toner adhered to the electrode 42 (shown as “None” in FIGS. 7A and 7C).

  On the other hand, 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. The loop electric lines of force were not formed, and the toner adhered to the control electrode 42 (indicated as “present” in FIGS. 7A and 7C). Further, in V1 / L1 = V2 / L2 (Comparative Example 2), as shown in FIG. 9, 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 (indicated as “present” in FIGS. 7A and 7C).

Moreover, it was confirmed from the results of simulation and experiment that the applied voltage and distance range related to the potential difference V1, the distance L1, the potential difference V2, and the distance L2 are as follows.
In other words, regarding the relationship between the potential differences V1 and V2, the voltage Vp is a voltage common to both, 300 to 1500V is the use range, and the voltage Vs contributing to the potential difference V1 is constant 0V (Vs = 0V). The maximum usable value of the voltage Vg contributing to V2 is 500 V in consideration of discharge with the electrodes 42 and 43 and the like. As a result, the potential difference V1 is set to 300 to 1500 V, and the potential difference V2 is set to a voltage within the range of 800 to 2000 V.

  Further, regarding the relationship between the distances L1 and L2, the gap on the printing surface side (recording medium means side) is a distance common to both, and the use range is 150 to 500 μm. The control electrode (first electrode) 42 Considering the range of the thickness of the substrate of 25 to 100 μm, the distance of the overlapping range of the distances L1 and L2 is 175 to 600 μm, and the supply side gap (the gap between the toner carrier 1 and the toner control means 4) The usable range was 100 to 400 μm, and the maximum usable distance between the end of the toner passage hole 41 and the common electrode 43 was 250 μm, so that the distance L1 was 275 to 1000 μm and the distance L2 was 425 to 850 μm. The distance that goes inside.

For these values, comparing the magnitude relationship in the above range,
V1 / L1 = 300 / 275-1500 / 275-300 / 1000-1500 / 1000 = 1.1-5.5-0.3-1.5
V2 / L2 = 800 / 425-2000 / 425-800 / 850-2000 / 850 = 1.9-4.7-0.9-2.3
It is.

  In the above description, the negatively charged toner is used. However, when the positively charged toner is used, the same behavior is exhibited by reversing the polarity of each voltage (the direction of the electric lines of force is reversed). Become.).

  Thus, 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, and the second electrode to the second electrode. When the distance from the first electrode to the counter electrode means is L2, the potential difference V1 is 300 to 1500 V, the potential difference V2 is 800 to 2000 V, the distance L1 is 275 to 1000 μm, the distance L2 is 425 to 850 μm, And voltage applying means for applying a voltage satisfying the relationship of V1 / L1 <V2 / L2 to the toner carrier, the first electrode, the second electrode, and the counter electrode means, respectively. An image can be formed without toner adhering to one electrode, and stable image quality can be maintained for a long time without clogging, dot shape disorder, and landing position disorder.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 10 is a schematic configuration diagram of the image forming apparatus according to the embodiment.
In this image forming apparatus, four units of the above-described embodiment are provided, and toner for four colors of yellow (Y), magenta (M), cyan (C), and black (K) is converted into a cloud and a toner control unit. 1 is an example of an image forming apparatus that performs ON / OFF control to form a color image.

  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.

  Here, the intermediate transfer recording member 103 is wound 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 31, 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.

  The toner supply unit 100 includes a toner carrier 1 that rotates in the same direction as the circumferential movement direction of the intermediate transfer recording medium 103, a rotating toner supply roller 15 that supplies toner to the toner carrier 1, and the toner carrier 1. Blade 14 for regulating the amount of toner.

  Here, toner is replenished from the toner replenishment roller 15 to the toner carrier 1 and frictional charging of the toner is performed by friction between the toner on the toner replenishment roller 15 and the toner carrier 1. Further, the blade 14 on the downstream side of the toner replenishing roller 15 keeps the toner amount on the surface of the toner carrier 1 to be a constant amount with a thin layer, and also stabilizes the toner charge amount.

  Then, the toner supplied by the toner supply unit 100 is turned on / off according to the image by the toner control unit 104, so that it flies onto the intermediate transfer recording body 103, and the color toner is transferred onto 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 a schematic configuration diagram of FIG.
In this embodiment, a toner carrier 101 in the form of a roller that carries toner T in a clouded state, recording medium means 3 to which toner T is attached, toner carrier 1 and recording medium means 3, And a toner control means 4 having a plurality of toner passage holes 41 arranged between the two.

  The toner carrier 101 has a predetermined pitch formed along the direction (here, the axial direction) orthogonal to the direction in which the toner T is conveyed at a predetermined interval in the direction in which the toner T is conveyed to the surface side (here, the circumferential direction). A bias voltage Vs having a different potential depending on the time is applied from the bias power source 5 to each electrode 111 of the toner carrier 101. This constitutes a means for converting the toner T into a cloud.

  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 11 and 11 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 101 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 101 interferes with the ON / OFF electric field on the surface of the toner carrier 101 on the toner carrier 101 side. 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.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Next, the average voltage Vs of the voltage with respect to the electrode 111 of the toner carrier 101, the bias voltage Vp applied to the counter electrode means 31, the control pulse voltage Vc applied to the control electrode 42 of the toner control means 4, and the common electrode 43 are applied. The voltage Vg 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 unit 31 of the recording medium unit 3 may be a DC voltage of +200 to +1500 V, for example, although it depends on the interval between the toner control unit 4 and the counter electrode unit 31. Here, DC + 300V is applied with an interval of 0.3 mm between the toner control means 4 and the counter electrode means 31, and the potential gradient draws the negatively charged toner toward the counter electrode means 31.

  By setting the relationship between the potentials applied to the electrodes 111, 42, 43, and 31 as described above, when the toner charged negatively is allowed to pass through the toner passage hole 41, the most positive side is set. Of the electric lines of force that emerge from the counter electrode means 31 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. 6A described above, 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 31 through the toner passage hole 41 are as follows. Without entering the control electrode 42 (bypassing the control electrode 42), most of the voltage 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 unit 31 and the common electrode 43 of the toner control unit 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. As can be seen from FIG. 6A, the upper side of the control electrode 42 to which +50 V is applied is common from the counter electrode means 31 through the toner passage hole 41. Since the electric lines of force 10 entering the electrode 43 are 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. The potential 0V of the toner repels the toner T toward the toner carrying member 101, and the toner T does not adhere to the toner control means 4, and the counter electrode means as shown in FIG. Since there is no electric force line through which the electric force from 31 passes 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 31 and the toner carrier 101 is V1, the distance between the counter electrode means 31 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 31 is V2, and the distance from the common electrode (second electrode) 43 to the counter electrode means 31 through the control electrode (first electrode) 42 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 31, respectively.

  As described above, the toner carrier that carries the toner in a clouded manner, the recording medium means to which the toner is adhered, and the plurality of toner passage holes arranged between the toner carrier and the recording medium means are provided. Toner control means, and the toner control means is provided with a control electrode for controlling the passage of the toner on at least one of the periphery of the toner passage hole and the inner wall of the hole on the surface of the toner carrier, and outside the control electrode. When a common electrode common to the plurality of toner passage holes is provided, and the toner on the toner carrier is allowed to pass through the toner passage hole of the toner control means toward the recording medium means, the recording medium means side and the toner control means By forming a line of electric force around the control electrode around the common electrode, a potential for attracting toner is applied to the surface of the control electrode and its surroundings. The adhesion of toner can be greatly reduced, the on / off control of toner passage can be stably performed, and 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 On the toner carrier side, it expands larger than the diameter of the toner passage hole, and it is possible to capture a large amount of clouded toner and fly it toward the printing surface, increasing the toner usage efficiency and ensuring printing density. The printing speed can be improved.

  Further, regarding the relationship of the potential applied to each electrode, when the DC bias of the electrode 111 of the toner carrier 101 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 101 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 31,
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 electrode 111, 42, 43, 31 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 101 increases due to high-speed printing, or when printing is performed using toner with a large amount of charged charge, 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 101 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 101, the combined electrostatic capacity with respect to the periphery of each toner is reduced, and as a result, the potential is increased.

  The toner potential Vt in the cloud state can be easily measured by applying a pulse voltage to each electrode 111 on the surface of the toner carrier 101 and setting the surface electrometer above the toner in the cloud state. Can be measured. More specifically, a toner control unit applies a pulse that causes clouding, rotates the toner carrier 101 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, 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. 12 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. 12, the amount of toner attached 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 results of FIG. 13, although the region supply amount toner is small toner adhesion is not to the electrodes 42, 43, 0.9 mg / cm ² weight supply toner is increased toner potential Vt is -80V, and the control electrode Toner adhesion to 42 begins to occur.

  This is equivalently because the potential of the toner carrier 101 increases to the negative side and the potential difference with the common electrode 42 of the toner control means 4 becomes smaller, so that it exits from the counter electrode means 31 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 101 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 the 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 carrying member 101 is Vt, the relationship between the potentials when turning on the toner is
Vp>Vc-on> (Vs + Vt)> Vg
In the case of negatively charged toner, Vp increases to the positive potential side, and in the case of positively charged toner, Vp increases 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 31 are set as described above. In other words, the potentials on the toner supply side are 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. In this case, even when the toner is not clouded (no pulse is applied), the toner is not attached to the control electrode or the like by setting the above-described potential relationship, so that the reliability is improved.

  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.

  In the above example, the condition in which the cloud pulse is applied to the plurality of electrodes on the surface of the toner carrier and the toner is in the cloud state has been described. However, as in the first embodiment, the toner is allowed to fly. When the potential of the toner viewed from the control electrode side in a non-state is Vt, setting the same condition as described above has an effect of avoiding toner adhesion to the electrode. That is, even when the application of the cloud pulse is turned off and there is no toner cloud, a slight amount of toner is floating. Although the slight potential of the floating toner is negligible, there is a toner potential landing on the surface of the toner carrying member, and (Vs + Vt) in consideration of this potential Vt is also set in the same condition range as above. The same effect can be obtained.

  As described above, a time-varying potential is applied to the means for flying the toner on the surface of the toner carrying member to form a cloud. For example, the toner is supplied from a toner carrier having a plurality of electrodes provided at a predetermined pitch in a direction orthogonal to the direction in which the toner is conveyed on the surface of the toner carrier for conveying and supplying the toner. Here, when there is no common electrode of the toner control means, and when the potential setting to each electrode is not within the above-described range, a decrease in reliability is unavoidable, such as toner adhesion to the electrode rapidly occurring. In addition, since the use efficiency of the clouded toner is greatly reduced, it is impossible to secure an image density and achieve an image forming apparatus for high-speed printing.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a schematic configuration diagram of the image forming apparatus according to the embodiment.
This image forming apparatus is the same as the image forming apparatus of the second embodiment described above, and here, as the toner supply unit 100, as in the third embodiment, a plurality of voltages that apply a voltage to make the toner cloudy. The toner carrier 101 having the electrodes 111 arranged side by side, a rotating toner supply roller 113 for supplying toner to the toner carrier 101, and a blade 114 for regulating the amount of toner on the toner carrier 101 are provided.

  Here, toner is replenished from the toner replenishing roller 113 to the toner carrier 101 and frictional charging of the toner is performed by friction between the toner on the toner replenishing roller 113 and the toner carrier 101. 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 101 constant by a thin layer and stabilizes the toner charge amount.

  Then, the toner supplied by the toner supply unit 100 is ON / OFF controlled according to the image by the toner control unit 4 so as to fly on the intermediate transfer recording body 103, and a color toner image on the intermediate transfer recording body 103. Is formed.

  The rest is the same as in the second embodiment, and a description thereof will be omitted.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 15 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 made 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 means such as a charging roller (not shown), thereby recording paper P 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.

  In this configuration, there is a paper transport belt 151 such as polyimide and the recording paper 150 between the toner control means 4 that controls the passage of toner and the counter electrode means 31 that applies a bias for guiding the toner after passing to the recording paper 150. Therefore, it is difficult to set the interval between the toner control unit 4 and the counter electrode unit 31 very narrow, but on the other hand, since a color image is formed directly 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.

  Further, the belt cleaning mechanism as in the configurations of the second and fourth embodiments is not necessary, which is advantageous for realizing a small 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 the toner carrier 101 used in the above-described image forming apparatus will be described with reference to FIG. FIG. 15A is a schematic plan view illustrating a state where the toner carrier is developed, and FIG. 15B is a schematic cross-sectional view illustrating the same.
In this example, a plurality of electrodes are provided on the surface of the toner carrier, two electrodes for every other pair are used in common, and a two-phase pulse (see FIG. 17) 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.

  In this toner carrier 101, an A-phase electrode 111A and a B-phase electrode 111B are provided as a plurality of electrodes 111 on the surface of an insulating substrate 101A, and a surface protective layer 101B is provided thereon. Comb-like electrodes 111A and 111B are provided in parallel at a fine pitch in a direction orthogonal to the toner transport direction, and both sides are connected to an external two-phase pulse generation circuit (not shown) by common bus lines 111Aa and 111Ba, respectively. It is connected.

  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 101 rotates 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 used in the above-described image forming apparatus will be described with reference to FIG. FIG. 18A is a schematic plan view illustrating a state where the toner carrier is unfolded, and FIG. 18B 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. 19, 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 in accordance 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. The cleaning is configured to come into contact with the surface of the toner carrier 101 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 101, an 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 carrier configured as described above, a flying pulse is applied from the drive circuit to form a flying electric field, so that the charged toner on the toner carrier receives a repulsive force and / or suction force and moves up and down. Flight in the direction and transport in the traveling wave direction are performed.

Next, an example of a specific configuration of the toner supply unit 100 in the image forming apparatus according to the fourth and fifth 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 304 by the rotation and magnetic force of the mag brush roller 304. 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 101 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.

  The above-described voltage shown in FIG. 17 or FIG. At a position facing the mag brush roller 204, an electric field is generated between the toner carrier 101 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 101. The toner that has reached the surface of the toner carrier 101 is clouded by the electric field formed by the voltage applied to the electrode 111 from the second voltage application unit 212, and is generated by the rotation of the toner carrier 101 or the traveling wave electric field of the toner carrier 101. Be transported.

  Then, the toner conveyed to a position facing the toner control electrode 104 is selectively jumped to the recording medium means side by the control electric field of toner control ON / OFF of the control electrode 42, and the dot printing of the toner is controlled. The

Next, an example of a specific configuration of the toner supply unit 100 in the image forming apparatus according to the fourth and fifth 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 101 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 applying unit 221. A voltage is applied to the electrode 111 by the second voltage applying means 222 in the toner carrier 101. Accordingly, at the position facing the toner carrier 101, an electric field is generated between the toner carrier 101 and the toner supply roller 113 by the first and second voltage applying means 221 and 222, and the electrostatic force from the electric field is received. The toner is separated from the toner supply roller 113 and moves to the surface of the toner carrier 101.

  Similar to the above example, the toner that reaches the surface of the toner carrier 101 is clouded by the electric field formed by the voltage applied to the electrode 11 from the second voltage applying means 222, and the rotation of the toner carrier 101 or the toner carrier It is carried by the traveling wave electric field of the body 101.

  Then, the toner conveyed to a position facing the toner control electrode 104 is selectively jumped to the recording medium means side by the control electric field of toner control ON / OFF of the control electrode 42, and the dot printing of the toner is controlled. 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 101 and is collected from the surface of the toner carrier 101 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.

  In the above description, mainly negatively charged toner is taken as an example, but positively charged toner can also be used.

It is a typical lineblock diagram showing a 1st embodiment of the present invention. It is a perspective explanatory view similarly. It is explanatory drawing which shows an example of the control pulse 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 explanatory drawing which shows the electric force line which passes a toner passage hole based on the simulation result of the two-dimensional cross-sectional electric field strength distribution when the toner control means is in a state where the toner can pass, and (b) is also when the toner cannot pass through It is explanatory drawing which shows the electric lines of force. It is explanatory drawing with which it uses for description of an experimental result. It is explanatory drawing which shows the electric force line similar to FIG. 6 in the case of the comparative example 1. FIG. It is explanatory drawing which shows the electric force line similar to FIG. 6 in the case of the comparative example 2. FIG. It is a typical explanatory view showing an image forming apparatus concerning a 2nd embodiment of the present invention. It is a typical block diagram which shows 3rd Embodiment of this invention. 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. It is a typical explanatory view showing an image forming apparatus concerning a 4th embodiment of the present invention. It is a typical explanatory view showing an image forming device concerning a 5th embodiment of the present invention. (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. 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. It is a typical explanatory view showing a basic configuration of a conventional direct recording system apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Toner carrier 3 ... Recording medium means 4 ... Toner control means 31 ... Counter electrode means 41 ... Toner passage hole 42 ... Control electrode 43 ... Common electrode 100 ... Toner supply unit 101 ... Toner carrier 103 ... Intermediate transfer recording body 104 ... toner control means 111 ... electrode 150 ... recording paper

Claims (12)

A toner carrier for carrying toner;
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 on the toner passage opening side of the toner control means on the toner carrying member side surface, and a second electrode provided at a position away 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,
The potential difference V1 is 300 to 1500 V, the potential difference V2 is 800 to 2000 V, the distance L1 is 275 to 1000 μm, the distance L2 is 425 to 850 μm, and the relationship V1 / L1 <V2 / L2 is established.
An image forming apparatus comprising: a voltage applying unit that applies a voltage to each of the toner carrier, the first electrode, the second electrode, and the counter electrode unit.   2. The image forming apparatus according to claim 1, wherein when the toner is a negatively charged toner, the voltage Vp applied to the counter electrode means increases to the positive potential side, and when the toner is a positively charged toner, the counter electrode. An image forming apparatus characterized in that the voltage Vp applied to the means increases to the negative potential side. 3. The image forming apparatus according to claim 1, wherein the relationship between the potentials when the toner cannot pass through the toner passage opening is expressed as Vs, where Vs is an average potential of voltages applied to the toner carrier. When the voltage applied to the second electrode is Vg and the voltage applied to the first electrode is Vc-off,
Vs> Vg and Vs> Vc-off
When the toner is a negatively charged toner, the average potential Vs is increased to the positive potential side, and when the toner is a positively charged toner, the average potential Vs is increased to the negative potential side. An image forming apparatus.   4. The image forming apparatus according to claim 3, wherein when the potential of the toner layer on the toner carrier is Vt, and the toner is a negatively charged toner, the relationship is Vs> Vt> Vg, An image forming apparatus, wherein Vs <Vt <Vg when V is positively charged toner.   5. The image forming apparatus according to claim 1, wherein the toner carrying member carries the toner in a cloud form, and electric lines of force formed between the second electrode and the counter electrode unit. An image forming apparatus, wherein the toner is present between the toner control means.   6. The image forming apparatus according to claim 5, wherein the toner carrying member has a plurality of electrodes arranged at a predetermined interval on the surface side, and repels the direction in which the toner is sucked between adjacent electrodes. With respect to the pitch between the two-phase electrodes applied to the electrodes, or the n-phase pitch between the n-phase electrodes when the n-phase voltage is applied to each n electrodes An image forming apparatus characterized in that a distance between a surface of the toner carrier and a side surface of the toner carrier of the toner control unit is large.   7. The image forming apparatus according to claim 1, wherein the recording medium means is recording paper, and a counter electrode means provided on the back surface of the recording paper is disposed. .   7. The image forming apparatus according to claim 1, wherein the recording medium unit is an intermediate transfer medium, and the intermediate transfer medium itself also serves as the counter electrode unit or the counter electrode on a back surface of the intermediate transfer medium. An image forming apparatus provided with means.   9. The image forming apparatus according to claim 1, wherein a color image is formed on the recording medium means by superimposing the toners of different colors. 10. The image forming apparatus according to claim 1, wherein when the toner of the toner carrying member is allowed to pass through the toner passing opening of the toner control unit toward the recording medium unit, An image forming apparatus, wherein lines of electric force are formed in a loop shape around the first electrode between the recording medium means side and the second electrode of the toner control means.   11. The image forming apparatus according to claim 1, further comprising an insulating layer that covers the first electrode.   12. The image forming apparatus according to claim 11, wherein the insulating layer covering the first electrode is formed of a resin material and has a thickness in the range of 2 to 20 [mu] m.

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