JP5186847B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image by flying and adhering toner ejected from a toner carrying member to recording medium means through a toner passage hole that is controlled to open and close.

  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.

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. 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.
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 carrier 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 hole, 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 has an object to reduce the occurrence of image density unevenness.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
It has a plurality of electrodes arranged at predetermined intervals on the surface side that carry toner and carry it in the form of a cloud, and the relationship in which the toner is sucked and repelled alternately between adjacent electrodes A toner carrier to which an n-phase pulse voltage is applied;
A recording medium means to which the toner is attached;
A plurality of toner passage holes arranged between the toner carrier and the recording medium means, and a control electrode for controlling the passage of the toner are provided at least around the toner passage hole and the inner wall of the hole. Toner control means;
Means for applying a control pulse having a repetition period Tc to the control electrode of the toner control means when printing continuous dots;
The pulsed voltage having an n-phase period Ts and a relationship of Tc> Ts / n in relation to the repetition period Tc of the control pulse is applied to the electrode of the toner carrier. It means for, has a configuration which comprises a.

  Here, a common electrode common to a plurality of toner passage holes is provided outside the control electrode in the toner control means, and a voltage of a pulse voltage having an average potential Vs is applied to the toner carrying member to control the control electrode of the toner control means. In contrast, the voltage Vc-on is applied when the toner is allowed to pass through the toner passage hole, the voltage Vc-off is applied when the toner is not allowed to pass through the toner passage hole, and the voltage Vg is applied to the common electrode. When the bias voltage Vp is applied to the recording medium means side in order to guide the toner that has passed through the toner control means to the recording medium means to adhere the toner, The relationship is Vp> Vc-on> Vs> Vg, and when the toner is negatively charged toner, the bias voltage Vp is increased to the positive potential side. When the toner is positively charged toner, the bias voltage Vp is negatively charged. It can be set as the setting which becomes high at the position side.

  In this case, the relationship between the potentials when the toner cannot pass through the toner passage hole is Vs> Vg, and Vs> Vc-off, and the toner is a negatively charged toner. Can be configured such that the average potential Vs increases to the positive potential side, and in the case of positively charged toner, the average potential Vs increases to the negative potential side.

  Further, a voltage Vc-on is applied when the pulse voltage of the average potential Vs of the toner carrying member is applied so that the toner can pass through the toner passage hole with respect to the control electrode of the toner control means, and the toner passes through the toner passage hole. The recording medium is applied to apply the voltage Vc-off to make it impossible to pass the toner, apply the voltage Vg to the common electrode, and guide the toner that has passed through the toner control means to the recording medium means side to adhere the toner. When the bias voltage Vp is applied to the means side, when the toner is present on the surface of the toner carrier, the potential due to the toner when the toner carrier side is viewed from the control electrode side of the toner control means is Vt. The relationship between the potentials when the toner is allowed to pass through the toner passage hole is Vp> Vc-on> (Vs + Vt)> Vg, and when the toner is negatively charged toner, (Vs + Vt) is positive. In the case of positively charged toner, (Vs + Vt) can be set to increase toward the negative potential side.

  In this case, the relationship between the potentials when the toner cannot pass through the toner passage hole is (Vs + Vt)> Vg and (Vs + Vt)> Vc-off, and the toner is negative. In the case of charged toner, the potential (Vs + Vt) is increased to the positive potential side. In the case of positively charged toner, the potential (Vs + Vt) is increased to the negative potential side.

  In addition, the common electrode of the toner control unit can be configured to surround the outside of the control electrode in a ring shape with an insulating region interposed therebetween.

  Further, the recording medium means may be recording paper, and a bias voltage may be applied to the counter electrode means provided on the back surface of the recording paper.

  Further, the recording medium means may be an intermediate transfer medium, and a bias voltage may be applied to the intermediate transfer medium itself or electrode means 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.

According to the onset bright, it can be performed a plurality of times of toner flying cloud within one period of the control pulse, and can reduce image density unevenness, can ensure proper image density.

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, the roller-shaped toner carrier 1 that carries the toner T in a clouded state, the recording medium means 3 to which the toner T is attached, the toner carrier 1 and the 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 1 has a predetermined pitch formed along a direction (here, an axial direction) orthogonal to a direction in which the toner T is conveyed at a predetermined interval in the direction (here, the circumferential direction) in which the toner T is conveyed to the surface side. Each of the electrodes 111 of the toner carrier 1 is supplied with a pulse voltage (hereinafter referred to as “average voltage Vs” having different potentials depending on time from the voltage applying power source (pulse generating means) 5. Also referred to as “cloud pulse”). This constitutes a means for converting the toner T into a cloud.

  For example, a pulse voltage having a frequency of 0.5 KHz to 7 KHz is applied, and the interval between the electrodes 111 and 111 is provided at a fine pitch, so that a strong electric field is formed between the electrodes 111 and 111. Therefore, the toner T flies vigorously from the surface of the electrode 11 at a potential repelling the charged polarity of the toner T, and the toner T that has flew is attracted to the electrode 11 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 the 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 11.

An example of the toner carrier 1 will be described with reference to FIG. 2A is a schematic plan view illustrating a state where the toner carrier is unfolded, and FIG. 2B 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, two pairs of electrodes are provided in common every other pair, and two-phase pulses having different phases by 180 ° (see FIG. 3) are 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. Comb-like electrodes 111A and 111B are provided in parallel at a fine pitch in a direction orthogonal to the toner transport direction, and external two-phase pulse generation circuits (voltage applying means) are connected to both sides by common bus lines 111Aa and 111Ba. 5) are connected to each other.

  The pulse voltage (cloud pulse) applied to the electrodes 111A and 111B is, for example, a pulse voltage having a frequency of 0.5 KHz to 7 KHz (a DC voltage can also be included in the bias), and its peak value is ± 60 to ±±. A pulse voltage according to the electrode width and electrode interval, such as 300 V, is applied. 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.

  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 holes 41 on the toner supply side surface (surface on the toner carrier 1 side) of the toner control means 4. A control electrode 42 is provided in a ring shape, and a common electrode 43 common to the plurality of toner passage holes 41 is provided outside the control electrode 42 with respect to the toner passage holes 41 via an insulating region.

  For example, a control pulse Vc as shown in FIG. 4 is applied from the control pulse generating means 6 to the control electrode 42 of the toner control means 4. 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. Further, the voltage Vg is constantly applied from the power supply means 7 to the common electrode 43. The control electrode 42 of the toner control means 4 can operate only around the passage hole 41, but is provided on both the inner wall surface of the passage hole 41 or the inner wall surface of the passage hole 41 and the periphery on the toner carrier 1 side. It may be.

  On the recording medium means 3 side, a counter electrode means serving as a bias voltage applying means is applied to the back surface of the recording medium means 3 to apply a bias voltage for attaching the toner T that has passed the toner control means 4 to the recording medium means 3. A bias voltage Vp from the bias power supply unit 8 is applied to adhere the toner T that has passed through the toner control unit 4 to the recording medium unit 3. 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, an electrode is embedded inside (an arrangement in which the electrode on the recording medium means side is an internal electrode) or a back electrode 31 is disposed on the back surface of the intermediate transfer recording medium. be able to.

  Here, as means for converting the toner on the surface of the toner carrier 1 into a cloud, a plurality of electrodes 111 provided on the surface of the toner carrier 1 are provided, and a voltage having an average potential Vs is applied to each 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 1 and the toner control means 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 causes interference with the ON / OFF electric field on the surface of the toner carrier 1 on the toner carrier 1 side, and the toner controller 4 described later. This is because the loop 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.

Next, an example of a specific configuration of the toner control unit 4 will be described with reference to FIG. In addition,
FIG. 5A is an explanatory view on the printing surface side of the toner control means, and FIG. 5B is an explanatory view of the toner supply side surface.
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 (drive circuit) for controlling ON / OFF of the passage of the toner T, and the common electrode 43 is connected to a common lead pattern 43a. Yes. 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.

  As described above, the common electrode of the toner control unit is configured to surround the outer side 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 on the outer side of the control electrode are between Can be formed as independent lines of electric force for each toner passage hole, so that mutual interference during multi-driving (drive that causes toner to fly from a plurality of nozzle passage holes) (under the condition of other toner passage 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. FIG. 6A is an explanatory diagram on the printing surface side of the toner control means, and FIG. 6B is an explanatory diagram of the toner supply side surface.
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.

  In the image forming apparatus configured as described above, by applying a pulse voltage of the average potential Vs to the electrode 11 of the toner carrier 1, the toner T flies over the toner carrier 1 to be clouded, and the toner The toner T is transported by the rotation of the carrier 1 or by the traveling wave electric field. On the other hand, the printing bias voltage Vp is applied to the back electrode 31 on the recording medium means 3 side.

  In this state, when the voltage Vg is applied to the common electrode 43 of the toner control means 4 so that the toner T can pass through the toner passage hole 41 with respect to the control electrode 42 (ON state), it is shown in FIG. When the voltage Vc-on at the time of ON is applied and the toner T enters a state where it cannot pass through the toner passage hole 41 (OFF state), the voltage Vc-off at the time of OFF shown in FIG. 4 is applied.

  In this case, by setting the voltages for these electrodes 111, 31, 42, 43 as described later, the toner T of the toner carrier 1 can pass through the toner control means 4 toward the recording medium means 3. In this case, the lines of electric force 10 are formed in a loop shape around the control electrode 42 for controlling the passage of toner between the recording medium means 3 side and the common electrode 43 of the toner control means 4.

  As a result, the clouded toner on the toner carrier 1 rides on the electric field generated by the electric force lines 10, passes through the toner passage hole 41 of the toner control unit 4, and lands on the recording medium unit 3. Therefore, a toner image can be formed directly on the recording medium means 3 by ON / OFF control (open / close control) of each toner passage hole 41 of the toner control means 41 according to the image. Since the electric lines of force 10 are formed in a loop shape around the control electrode 42 that controls the passage of toner between the recording medium means 3 side and the common electrode 43 of the toner control means 4, the control electrode 42. In addition, toner adhesion to the periphery of the toner passage hole 41 is reduced, and the use efficiency of the toner is improved by making the toner cloud.

Here, the relationship between the cloud pulse applied to the electrode 111 of the toner carrier 1 and the control pulse Vc applied to the control electrode 42 of the toner control means 4 will be described with reference to FIGS. FIG. 7 is an explanatory diagram showing the phase relationship when the time axes of the control pulse and the cloud pulse are the same, and FIG. 8 is an explanatory diagram in the cross-sectional direction of a plurality of electrodes on the surface of the toner carrier.
Here, the pulse period of the control pulse Vc applied to the control electrode 42 that controls ON / OFF of the passage of toner (the repetition period of Vc-on when forming continuous dots) is Tc, and the toner on the toner carrier 1 Ts is a pulse period of a cloud pulse (here, the toner carrier is rotated by rotation of the two-phase pulse) applied to the electrode group 111 on the surface of the toner carrier 1 in order to make the toner cloud.

  In this case, assuming that the toner is a negatively charged toner, as shown in FIG. 8A, during the period of the cloud pulse period Ts, the B phase has an “L” (low) potential and the A phase as compared to the A phase. Is higher than the B phase, the toner T flies from the B phase electrode 111 toward the A phase electrode 111, and a large amount of toner collects on the surface of the A phase electrode 111. This is because the toner jumps along the electric lines of force from the A-phase electrode 111 toward the B-phase electrode 111, and after the velocity in the Y direction becomes zero, it is attracted to the surface of the A-phase electrode 111. Because it is.

  On the other hand, as shown in FIG. 8B, in the period of the cloud pulse period Ts, the A phase is “L” (low) potential compared to the B phase, and the B phase is “H” (high) compared to the A phase. ) When the potential is applied, the toner T flies from the A-phase electrode 111 toward the B-phase electrode 111 and collects again on the surface of the B-phase electrode 111.

  As described above, in the example of the two-phase (n = 2) cloud pulse, the toner T repeats flying twice from the surface of the toner carrier 1 per cycle Ts of the cloud pulse. In the case of a cloud pulse of a three-phase traveling wave, three flights are performed per pitch of electrodes of the A to C phases per cloud pulse period.

  Therefore, in order to eliminate the density unevenness of the image and obtain a normal image, at least a toner flying cloud (repulsion and suction) is required during one cycle Tc of the control pulse Vc for controlling the toner passage ON / OFF. By performing it twice or more, the clouding of the toner progresses, and sufficient toner can fly.

  That is, a means for applying a control pulse having a repetition period Tc to the control electrode of the toner control means when printing continuous dots, and a pulse voltage of an n-phase period Tc to the electrode of the toner carrier. And a means for applying a pulse voltage having a relationship of Tc> Ts / n in relation to the repetition period Tc of the control pulse, so that the toner flying cloud can be carried out a plurality of times within one period of the control pulse. It is possible to reduce the unevenness of image density and to secure a normal image density.

  Next, regarding the average potential Vs of the pulse voltage for the electrode 111 of the toner carrier 1, the bias voltage Vp on the recording medium means 3 side, the control pulse voltage Vc for the control electrode 42 of the toner control means 4, and the voltage Vg for the common electrode 43, This will be described with reference to FIG. FIG. 9 is an explanatory diagram showing electric lines of force that pass through the toner passage holes based on the simulation results of the two-dimensional cross-sectional electric field intensity distribution of the toner carrier 1, the toner control means 4, and the recording medium means 3.

  A cloud pulse having an average potential Vs (voltage at which the potential varies with time) is applied to the electrode 111 of the toner carrier 1. In this case, the voltage peak value of the cloud pulse is set according to the electrode pitch, the toner 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 1 with respect to the toner control means 4 is 0V, and the average potential 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-125 V, and the relationship with the average potential Vs of the pulse voltage to the toner carrier 1 is a bias in the direction in which the toner T is always directed to the toner carrier 1 side. Therefore, no toner adheres to the surface of the common electrode 43.

  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 (state incapable of passing: OFF state) is −125V. Although the bias voltage Vp to the back electrode 31 of the recording medium means 3 depends on the interval between the toner control means 4 and the recording medium means 3, for example, a DC voltage of +200 to +1500 V may be applied. Here, DC + 300V is applied with an interval of 0.3 mm between the toner control means 4 and the recording medium means 3, and a potential gradient that draws negatively charged toner to the surface of the recording medium means 3 is used.

  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 31, it is most positive. Of the electric force lines that come out from the electrode 31 on the recording medium means 3 side with a high potential, most of the electric force lines that pass through the toner passage hole 41 of the toner control means 4 pass through the toner passage hole 41 and then have the highest potential. The low common electrode 43 is entered. 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.

  For this reason, as shown in FIG. 9A, when the toner T is allowed to pass through the toner passage hole 41 (ON state), the electricity passing through the toner passage hole 41 from the electrode 31 on the previous recording medium means 3 side. The force line 10 does not enter the control electrode 42 (bypassing the control electrode 42), and most of the force line 10 enters the common electrode 43 having the lowest potential of −125 V, and thus has a shape that expands in a loop shape. That is, the electric lines of force 10 are formed in a loop shape around the control electrode 42 between the recording medium means 3 side and the common electrode 43 of the toner control means 4.

  Therefore, the negatively charged toner T in the cloud state on the toner carrier 1 passes through the toner passage hole 41 along the electric force lines 10 and a large amount 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 1 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 the simulation result of FIG. 9A, the toner passing hole 41 is passed from the electrode on the recording medium means 3 side above the control electrode 42 to which +50 V is applied. Since the electric lines of force 10 passing through the common electrode 43 through the cover 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. Is a relationship that repels the toner T toward the toner carrier 1, and the toner T does not adhere to the toner control means 4, and the recording medium means 3 side as shown in FIG. 9B. Since there is no electric force line through which the electric force from the electrode 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).

  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 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 recording medium means side and the common electrode of the toner control means. Thus, electric lines of force can be formed in a loop shape.

That is, when a pulse voltage having 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 to the control electrode 42 of the toner control means 4. And the voltage Vc-off is applied when the toner cannot pass through the toner passage hole 41, the voltage Vg is applied to the common electrode 43, and the toner that has passed through the toner control means 4 is applied. When a bias voltage Vp is applied to the recording medium means 3 in order to guide the recording medium means 3 to adhere toner,
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 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 1 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 becomes smaller, and as a result, the potential increases.

  The measurement of the toner potential Vt in the cloud state can be easily performed by applying a pulse voltage to each electrode 11 on the surface of the toner carrier 1 and setting the surface potential meter above the supplied 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 potential meter is installed about 2 mm above the surface of the toner carrier 1 and measured. The results in FIG. 10 are for Vo when the charged charge amount is from −15 to −25 μC / g, and when the toner potential is Vt when the toner is in a cloud state with a flying height in the range 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. 10, 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 of FIG. 11, in the region where the amount of supplied toner is small, toner does not adhere to the electrodes 42 and 43, but the amount of supplied toner increases and the toner potential Vt becomes −80 V at 0.9 mg / cm ^2. Toner adhesion to 42 begins to occur.

  This is because the potential of the toner carrier 1 is equivalently increased to the minus side and the potential difference from the common electrode 42 of the toner control means 4 is reduced, so that the toner passing hole 42 comes out of the recording medium means 3 side electrode. This is because the electric lines of force that directly enter the toner carrier 1 increase among the electric lines of force passing through, and the loop-shaped electric lines of force that enter the common electrode 43 decrease. 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 side of the control electrode 42 in the cloud state where the charged toner flies from the surface of the toner carrier 1 is Vt (the other conditions are the same as above), the toner passage is turned on. The relationship between each potential is
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 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. Is applied to the electrode, and the toner carrier is applied to the pitch p between the two phases applied to the electrodes (or the pitch between the n-phase electrodes when the 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 when the toner is in the cloud state by applying the cloud pulse to the plurality of electrodes on the surface of the toner carrier has been described, but the toner viewed from the control electrode side in the state where the toner is not flying When the potential due to is set to 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 second embodiment of the present invention will be described with reference to FIG. FIG. 12 is a schematic configuration diagram of the same child form.
In this embodiment, in addition to the first embodiment, each toner passage hole 41 is surrounded by each toner passage hole 41 around the side of the recording medium means 3 of the toner control means 4 (the surface on the recording medium means 3 side). The individual back electrode 44 having a larger area than the control electrode 42 is individually provided, and the same potential Vs (= Vr) as that of the control electrode 42 is always applied to the individual back electrode 44.

An example of a specific configuration of the toner control unit 4 will be described with reference to FIG.
This toner control means 4 has a width of 10 to 100 μm on the toner supply side (toner carrier 11 side) surface of the insulating substrate (base material) 45 so as to surround the toner passage hole 41 as described in FIG. A ring-shaped control electrode 42 is provided, and the entire space in which the common electrode 43 for applying the common bias voltage Vg to the plurality of toner passage holes 41 is spaced from the control electrode 42 with an interval of an insulating region of 20 to 50 μm is covered. It is provided in a solid shape.

  On the other hand, on the recording medium means side (printing surface side) of the insulating substrate 45, a ring-shaped individual back electrode 44 having a diameter larger than that of the control electrode 42 so as to surround the toner passage hole 41 is provided. The individual back electrode 44 is formed by, for example, Al vapor deposition.

  The other configurations of the toner carrier 1, the recording medium means 3 and the like are the same as the basic configuration, and thus the description thereof is omitted.

  In the toner control means 4 configured as described above, the electric field distributions of the electrodes when +50 V, −125 V, and +50 V are applied as the potential Vc for each control electrode 42, the potential Vg for the common electrode 43, and the potential Vr for the individual back electrode 44, respectively. The simulation result is shown in FIG.

  Here, the potential Vr of the individual back electrode 44 and the potential Vc of the control electrode 41 are the same potential, and the average potential Vs with respect to the electrode 11 of the toner carrier 1 is 0V.

  As a result, when the toner is allowed to pass through the toner passage hole 41 (ON state), the loop-shaped electric field (electric field lines 10) that takes in the toner in the cloud state and flies to the printing surface side is described above. Compared to the case of FIG. 9A (the case where there is no individual back electrode 44), it can be seen that the width is large and the amount of the electric lines of force 10 passing through the toner passage hole 41 is large.

  In the case of FIG. 9A, the electric field of the voltage Vg of the common electrode 43 acts on the printing surface side, and also acts on the vicinity of the toner passage hole 41 on the printing surface side, from the printing bias Vp. 14 is limited, whereas in the example of FIG. 14, the voltage Vr of the individual back electrode 44 is the same potential as the voltage Vc, and near the toner passage hole 41 on the control electrode printing surface side. This is a result that the electric field lines passing through the toner passage hole 41 are increased because the surface potential is higher than that in the case of FIG.

  At this time, by setting the area of the individual back electrode 44 to be larger than the area of each control electrode 42 of the toner control means 4, the above effect becomes more remarkable. Alternatively, the shape of each control electrode 42 and each individual back electrode 44 of the toner control unit 4 is formed in a ring shape so as to surround the toner passage hole 44, and the outer diameter of the individual back electrode 44 with respect to the outer diameter of the control electrode 44. Even if the value is set to a larger value, the above effect becomes remarkable.

  When the potential Vr of the individual back electrode 44 of the toner control unit 4 and the potential Vc of the control electrode 42 are different from each other, for example, the voltage Vr of the individual back electrode 44 is set to a potential on the minus side of the voltage Vc of the control electrode 42. In this case, the amount of the electric force line 10 passing through the toner passage hole 41 is reduced. As a result, the force for flying the clouded toner toward the printing surface (recording medium means 3) is reduced, and the printing density is lowered. . Conversely, when the voltage Vr of the individual back electrode 44 is set to a positive potential with respect to the voltage Vc of the control electrode 42, the electric lines of force 10 passing through the toner passage hole 41 spread over the entire toner passage hole 41, and the toner passage hole 41. In the case where toner, fine powder, paper powder, or the like adheres to the toner passage hole 41, the flying toner collides and dot missing tends to occur.

  Therefore, the voltage Vc of the control electrode 42 and the voltage Vr of the individual back electrode 44 are applied with the same voltage, so that the strength of the electric field that causes the toner to fly to the printing surface is maintained, and the hole diameter of the toner passage hole 41 is maintained. A high-resolution image can be obtained by reducing the formed dot diameter, and an increase in driver cost can be suppressed.

  As for the shapes of the control electrode 42 and the individual back electrode 44 for obtaining a greater effect, the area of the individual back electrode 44 is larger than the area of each control electrode 42 of the toner control means 41 as described above. Set to shape. Alternatively, the shape of each control electrode 42 and each individual back electrode 44 of the toner control means 41 is substantially ring-shaped so as to surround the toner passage hole 41, and the outer diameter of the individual back electrode 44 with respect to the outer diameter of the control electrode 42. Set the dimensions larger.

  Further, as shown in FIG. 15, the control electrode 42 of the toner control means 41 and the individual back electrode 44 may be connected via a conduction pattern 46 provided on the inner wall surface of the toner passage hole 41. The conductive pattern 46 is formed by, for example, covering a portion other than the toner passage hole 41 with a metal mask, depositing a conductive material such as Al, Au, ITO, etc., forming a film on the inner wall surface by sputtering, or other than the toner passage hole 41. After forming a resist film on this portion, a conductive film can be formed by plating.

  In this case, by connecting the lead pattern 44a of the individual back electrode 44 to a driver (not shown) and applying the voltage Vc (= Vr), the lead pattern 42a from the control electrode 42 becomes unnecessary, so that the control electrode 42 side is reached. The toner adhesion is further reduced. In addition, it is sufficient that the number of drivers for generating control signals for forming toner dots by the toner passage holes 41 corresponds to the number of the nozzle passage holes 41.

  Here, the control electrode 42 and the individual back electrode 44 are connected to each other by the conductive pattern 46 provided on the inner wall surface of the toner passage hole 41. It is also possible to provide a through hole (hole) so that the control electrode 42 and the individual back electrode 44 are electrically connected. Since the through hole for conduction at this time only needs to consider conduction, it may be the minimum necessary hole, and the conduction treatment may also fill the inner wall of the hole. Can be filled by spraying.

Next, an image forming apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 16 is a schematic configuration diagram of 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 forms a cloud of toner for four colors of yellow (Y), magenta (M), cyan (C), and black (K) along the intermediate transfer recording body 103 which is a recording medium means. Four toner supply units 100y, 101m, 101c, and 101k (hereinafter referred to as “toner supply unit 100” when the colors are not distinguished. The same applies hereinafter) are arranged, and each toner supply unit 100 and the intermediate transfer recording member 103 are arranged. Between these, toner control means 4 similar to any one of the above-described embodiments is disposed.

  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 131 that is a 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 cylindrical toner carrier 1 in which a plurality of electrodes 111 for applying a voltage for arranging the toner into a cloud are arranged, and a rotating toner supply roller 113 for supplying toner to the toner carrier 1. And a blade 114 for regulating the amount of toner on the toner carrier 1.

  Here, toner is replenished to the toner carrier 1 from the toner replenishment roller 113 and the toner is frictionally charged by friction between the toner on the toner replenishment 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.

  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.

  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, an image forming apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 17 is a schematic configuration diagram of 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 according to the image of the toner control unit 104. 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.

  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 back electrode 131 for applying a bias for guiding the toner after the passage to the recording paper 150. In addition, it is difficult to set the distance between the toner control unit 4 and the back electrode 131 very narrow, but on the other hand, a color image is directly formed on the recording paper 150 and there is no transfer process. Nothing will happen.

  Further, the belt cleaning mechanism as in the configuration described with reference to FIG. 16 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, 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 the toner carrying member in a developed state, and FIG. 19B 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 toner carrier 101 is formed by forming the A-phase and B-phase electrodes 111A and 111B on the insulating base material 101A, and forming the C-phase electrode 111C after forming the insulating layer 101C on the upper layer, and on the C-phase electrode 111C. A surface protective layer 101B is provided.

  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.

  In addition, when fine particles such as an external additive of toner are deposited on the electrode surface during long-term use, the surfaces of the toner carriers 1 and 101 are cleaned by a cleaning mode sequence performed outside of the image formation time. This ensures the reliability of conveyance. The cleaning is configured to be in contact with the surface of the toner carrier 1 or 101 only in the cleaning mode, and is performed with a rotating brush, a blade, a suction slit, or 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 carriers 1 and 101 described above, the insulating substrate 101A as a base substrate is made of an insulating material such as resin or ceramics, or a base material made of a conductive material such as aluminum. In addition, an insulating film made of SiO ₂ or the like, or a film made of a flexible and 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 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 (or 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.

  To the toner carrier 1 (or 101), the voltage shown in FIG. 3 (or FIG. 19) 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 (or 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 1 (or 101) is clouded by the electric field formed by the voltage applied to the electrode 111 from the second voltage application unit 212, and the toner carrier 1 (or 101) rotates or the toner. It is conveyed by the traveling wave electric field of the carrier 101.

  Then, the toner conveyed to a position facing the toner control unit 104 is selectively jumped to the recording medium unit 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 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 (or 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 on the toner carrier 1 (or 101). Therefore, at a position facing the toner carrier 1 (or 101), an electric field is generated between the toner carrier 1 (or 101) and the toner supply roller 113 by the first and second voltage applying means 221 and 222, Under the electrostatic force from the electric field, the toner is separated from the toner supply roller 113 and moves to the surface of the toner carrier 1 (or 101).

  Similar to the above example, the toner reaching the surface of the toner carrier 1 (or 101) is clouded by the electric field formed by the voltage applied from the second voltage applying means 222 to the electrode 111, and the toner carrier 1 (or 101) or a traveling wave electric field of the toner carrier 1 (or 101).

  Then, the toner conveyed to a position facing the toner control unit 104 is selectively jumped to the recording medium unit 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 1 (or 101), and is collected from the surface of the toner carrier 1 (or 101) by a collecting unit (not shown). The 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. (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. 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. It is explanatory drawing with which it uses for description of the relationship between the period of a control pulse and a cloud pulse. FIG. 6 is an explanatory diagram for explaining a voltage applied to an electrode of a toner carrier and a behavior of the toner. (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 a diagram which shows the electric lines of force. 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 block diagram which shows 3rd Embodiment of this invention. (A) is explanatory drawing by the side of a printing surface which shows the other example of the toner control means of the embodiment, (b) is explanatory drawing by the side of a toner supply similarly. 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 of the embodiment is in a state where the toner can pass. It is a typical block diagram which shows the other example of the embodiment. It is a typical explanatory view showing an image forming apparatus concerning a 3rd embodiment of the present invention. It is a typical explanatory view showing an image forming apparatus concerning a 4th embodiment of the present invention. (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 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 (9)

It has a plurality of electrodes arranged at predetermined intervals on the surface side that carry toner and carry it in the form of a cloud, and the relationship in which the toner is sucked and repelled alternately between adjacent electrodes A toner carrier to which an n-phase pulse voltage is applied;
A recording medium means to which the toner is attached;
A plurality of toner passage holes arranged between the toner carrier and the recording medium means, and a control electrode for controlling the passage of the toner are provided at least around the toner passage hole and the inner wall of the hole. Toner control means;
Means for applying a control pulse having a repetition period Tc to the control electrode of the toner control means when printing continuous dots;
The pulsed voltage having an n-phase period Ts and a relationship of Tc> Ts / n in relation to the repetition period Tc of the control pulse is applied to the electrode of the toner carrier. an image forming apparatus characterized by comprising: means, a to. The image forming apparatus according to claim 1, wherein the toner control unit is provided with a common electrode common to the plurality of toner passage holes outside the control electrode,
Applying a pulse voltage having an average potential Vs to the toner carrier,
The voltage Vc-on is set when the toner is allowed to pass through the toner passage hole with respect to the control electrode of the toner control means, and the voltage Vc is set when the toner is not allowed to pass through the toner passage hole. -off is applied, voltage Vg is applied to the common electrode,
When a bias voltage Vp is applied to the recording medium means side in order to guide the toner that has passed through the toner control means to the recording medium means to adhere the toner,
The relationship between the potentials when the toner is allowed to pass is as follows:
Vp>Vc-on>Vs> Vg
The bias voltage Vp is increased to the positive potential side when the toner is a negatively charged toner, and the bias voltage Vp is set to be increased to the negative potential side when the toner is a positively charged toner. Image forming apparatus. The image forming apparatus according to claim 2, wherein the relationship between the potentials when the toner cannot pass through the toner passage hole is as follows:
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. When the toner is a positively charged toner, the average potential Vs is increased to the negative potential side. Image forming apparatus. The image forming apparatus according to claim 1.
Applying a pulsed voltage having an average potential Vs of the toner carrier;
The voltage Vc-on is set when the toner is allowed to pass through the toner passage hole with respect to the control electrode of the toner control means, and the voltage Vc is set when the toner is not allowed to pass through the toner passage hole. -off is applied, voltage Vg is applied to the common electrode,
When a bias voltage Vp is applied to the recording medium means side in order to guide the toner that has passed through the toner control means to the recording medium means side to adhere the toner,
When the toner is present on the surface of the toner carrier, the potential of the toner when the toner carrier is viewed from the control electrode side of the toner control means is Vt.
The relationship between each potential when the toner is allowed to pass through the toner passage hole is as follows:
Vp>Vc-on> (Vs + Vt)> Vg
When (Vs + Vt) is a negatively charged toner, the (Vs + Vt) is increased to the positive potential side. When the toner is a positively charged toner, (Vs + Vt) is set to be increased to the negative potential side. Image forming apparatus. 5. The image forming apparatus according to claim 4, wherein the relationship between the potentials when the toner cannot pass through the toner passage hole is as follows:
(Vs + Vt)> Vg and (Vs + Vt)> Vc−off
When the toner is a negatively charged toner, the potential (Vs + Vt) is increased to the positive potential side, and when the toner is a positively charged toner, the potential (Vs + Vt) is set to be increased to the negative potential side. An image forming apparatus.   6. The image forming apparatus according to claim 1, wherein the common electrode of the toner control unit has a shape surrounding the outside of the control electrode in a ring shape through an insulating region. Forming equipment.   7. The image forming apparatus according to claim 1, wherein the recording medium means is recording paper, and a bias voltage is applied to a counter electrode means provided on the back surface of the recording paper. Forming equipment.   7. The image forming apparatus according to claim 1, wherein the recording medium means is an intermediate transfer medium, and a bias voltage is applied to the intermediate transfer medium itself or electrode means provided on the back surface of the intermediate transfer medium. An image forming apparatus.   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.

Images