JPH10258537A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a printing speed and image quality, to miniaturize an apparatus, to reduce cost and to enhance reliability. SOLUTION: This apparatus comprises a toner supplying section 2 having a toner carrier body 22, an opposing electrode 25 placed in opposition to the carrier body 22, a high voltage power supply 31 that generates a voltage difference across the carrier body 22 and the opposing electrode 25, an insulation substrate disposed between the carrier body 22 and the opposing electrode 25, a plurality of gates 29 that are provided on the insulation substrate to be passing sections for a toner 21 and a control electrode 26 consisting of electrode groups provided at portions surrounding the plurality of gates 29. It is controlled so as to make a first voltage condition wherein an electric field that allows the toner to move from the carrier body 22 to gates 29 is applied to each of the electrode groups corresponding to image data and a second voltage condition wherein an electric field that allows the toner not to newly move from the carrier body 22 to gates 29 and dose not reduce the speed of the toner moving at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a printing section of a digital copying machine and a facsimile apparatus, a digital printer, a plotter, and the like, and an image forming apparatus for forming an image on a recording medium by flying a developer. It is about.

[0002]

2. Description of the Related Art In recent years, as an image forming apparatus for outputting an image signal as a visible image on a recording medium such as paper, for example, as described in Japanese Patent Application Laid-Open No. ) Is caused to fly by an electric force by applying an electric field, and by changing a potential applied to a control electrode including a plurality of passage holes arranged in a flight path to cause toner to adhere to the recording medium, thereby forming an image on the recording medium. 2. Description of the Related Art There has been proposed an image forming apparatus which directly forms an image on the upper surface.

[0003] In the above-mentioned prior art, the flying control of toner is performed by using a control electrode for applying a potential corresponding to image information to a plurality of electrodes as the control electrode.

[0004]

In an image forming apparatus of the type typified by the above prior art, control means for controlling the passage of charged particles through a gate is used. The image forming apparatus controls whether or not the toner can fly by controlling the electric field formed between the gate and the carrier, and causes the toner to reach the surface of the paper as a recording medium by the strong electric field formed by the counter electrode, thereby forming an image. Is formed.

[0005] In general, toner flying control is performed by controlling a control electrode having a gate disposed between opposing electrodes to a potential (hereinafter referred to as an ON potential) for permitting toner flying in accordance with image data, and to permit toner flying. Potential not to be applied (hereinafter, OFF
(Referred to as a potential) to control the flying of the toner to form an image. The ON potential is normally switched to the OFF potential after the toner reaches the recording medium or passes through the control electrode. For this reason, the application time (hereinafter referred to as the ON time) of the potential that causes the toner to fly does not become shorter than the time required for the toner to reach the control electrode. This ON time directly affects the printing speed and hinders the printing speed from increasing.

Further, the toner flying while the ON potential is being applied is always exposed to a strong electric field between the carrier and the control electrode. The flying toner is accelerated by the strong electric field, flies at a very high speed, reaches the surface of the recording medium, and rebounds at the arrival. Similarly, since the toner retains electric charge, the Coulomb force between the toners acts during the rebound, and the toner in the peripheral portion tends to spread in all directions. When the toner spreads during the rebound and reaches outside the dot area, the toner becomes flying toner. When the flying toner is generated, the outline of the dot becomes unclear, resulting in a blurred image from which no contrast can be obtained, which leads to image deterioration. Further, in such a situation, the reproducibility of the halftone is degraded, causing further problems.

If this problem occurs in a color image forming apparatus, a situation in which desired color reproducibility cannot be obtained is caused. In addition, in the case of a color image forming apparatus, in addition to the above, not only flying toner collides with a previously formed dot to destroy the dot, but also color mixture with other toner is easily caused by the scattered toner. ing.

In order to avoid this problem, it is conceivable to reduce the above-mentioned bounce by lowering the speed at which the toner flies, particularly, the speed at which the toner reaches the paper. One of the methods for reducing the speed at which the toner reaches the recording medium surface is to reduce the flying electric field formed by the high voltage applied to the counter electrode and the control electrode. When the flying electric field is reduced, the flying speed decreases, but the flying time until the toner passes through the control electrode becomes longer, and it is more difficult to increase the printing speed, which is not preferable.

Further, the spread of the toner during rebound is as follows.
This is due to the Coulomb force between the toner particles during the flight of the toner particles. Therefore, when the charge amount of the toner is reduced, the repulsive force due to the Coulomb force between the flying toner particles is weakened, the diffusion is reduced, and the toner scattering is reduced. However, it is difficult to control the amount of charge of the toner independently of other characteristic values of the toner layer carried on the carrier, for example, the amount of conveyance, the filling rate, the layer thickness, and the like. Since the state of the toner layer itself that controls the charge amount of the toner changes, the potential, shape, and position of the control electrode, the position and the potential of the counter electrode must be adjusted again, which is not preferable. Further, the increase in the number of parts and the increase in size and cost of the apparatus are inevitable, and when the charge amount of the toner is reduced, the formation of the toner layer tends to be unstable, and the flight control of the toner becomes unstable. A case where image formation cannot be obtained may occur. In addition, when the charge amount of the toner decreases, the acceleration force received by the toner decreases, but the time required for the toner to energize the control electrode also increases, and in this case, it is more difficult to increase the printing speed. Not suitable.

For this purpose, a method of controlling an electric potential applied to the control electrode to form an electric field for decelerating the toner (hereinafter referred to as a brake electric field) may be considered. When the brake electric field is formed, a problem occurs that the oppositely charged toner existing in the toner adheres to the control electrode. When toner adheres to the control electrode, the electric potential of the control electrode changes due to the charge of the toner, making it difficult to control the desired toner flight.
If toner adheres to the inside of the gate, a further problem occurs in that good toner flight cannot be obtained. When the amount of toner adhering to the inside of the gate increases, the gate eventually becomes clogged with the toner, and a state where printing cannot be performed occurs, resulting in image loss. From this, it was impossible to apply a potential capable of forming a large brake electric field (hereinafter referred to as a brake potential) to the control electrode.

In order to avoid this situation, a large brake electric field is applied only at the moment when the toner passes through the control electrode,
Other than this, a method of controlling so as to apply the OFF potential can be considered. However, in this control, ON potential, OFF
It is necessary to control three potentials, that is, a potential and a brake potential, which complicates the circuit configuration of the potential switching means, and inevitably increases the number of power supply components and increases the size, cost, and reliability.

[0012]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: a supply unit having a carrier for carrying a developer of at least one color; The disposed counter electrode, a high-voltage power supply unit that supplies a high voltage that generates a potential difference between the carrier and the counter electrode, an insulating substrate disposed between the carrier and the counter electrode, A control electrode comprising a plurality of gates provided on the insulating substrate and serving as a passage portion of the developer, and at least one electrode group provided around the plurality of gates; A first potential state for applying an electric field from the carrier to the gate according to the image data, which allows the developer to start moving to the gate, and a new potential from the carrier to the gate. Decelerates to the developing agent while moving And control circuit means capable of applying a plurality of potential states including a second potential state not to be applied to the electrode group. A predetermined potential is applied to a corresponding electrode of the electrode group by the control means. In the image forming apparatus, which controls the passage of the developer through the gate by applying the voltage to form an image on the surface of the recording medium conveyed between the control electrode and the counter electrode, the control unit includes: The application time of one potential state is shorter than the time required for an amount of the developer required to form one pixel to pass through the gate in a state where the first or second potential state is applied. Also control in a short time.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising: a supply unit having a carrier for carrying a developer of at least one color;
A counter electrode disposed opposite to the carrier; a high-voltage power supply for supplying a high voltage for generating a potential difference between the carrier and the counter electrode; and a high-voltage power supply disposed between the carrier and the counter electrode. A control electrode comprising: an insulating substrate; a plurality of gates provided on the insulating substrate to pass a developer; and at least one or more electrode groups provided around the plurality of gates. A first potential state in which an electric field capable of initiating movement from the carrier to the gate according to image data is applied to the individual electrodes of the control electrode, and the developer is newly applied to the gate from the carrier. And control circuit means capable of applying a plurality of potential states to the electrode group, including a second potential state that does not cause deceleration to the moving developer without causing any movement. The control means controls the position of the corresponding electrode in the electrode group. In the image forming apparatus, which controls the passage of the developer through the gate by applying a potential to form an image on the surface of the recording medium conveyed between the control electrode and the counter electrode, the control means includes: The application time of the first potential state is set to the time required for the amount of the developer necessary to form one pixel to reach the speed at which the developer can reach the gate in the first or second potential state. Control for longer time.

According to a third aspect of the present invention, there is provided an image forming apparatus, comprising: a supply unit having a carrier for carrying a developer of at least one color;
A counter electrode disposed opposite to the carrier; a high-voltage power supply for supplying a high voltage for generating a potential difference between the carrier and the counter electrode; and a high-voltage power supply disposed between the carrier and the counter electrode. A control electrode comprising: an insulating substrate; a plurality of gates provided on the insulating substrate to pass a developer; and at least one or more electrode groups provided around the plurality of gates. And a first potential state that gives an electric field from the carrier that allows the developer to start moving to the gate according to image data on the individual electrodes of the control electrode, and the developer from the carrier is A control circuit means capable of applying a plurality of potential states to the electrode group including a third potential state in which no new movement occurs to the gate and no acceleration is applied to the moving developer. Control means, and the electrode group is controlled by the control means. In an image forming apparatus that controls the passage of a developer through the gate by applying a predetermined potential to a corresponding electrode to form an image on the surface of a recording medium conveyed between the control electrode and the counter electrode The control means sets the application time of the first potential state to the first or third amount of the developer necessary to form one pixel.
Is controlled to a time shorter than the time required to pass through the gate from the state in which the carrier is carried in the state where the potential state is applied.

According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising: a supply unit having a carrier for carrying a developer of at least one color;
A counter electrode disposed opposite to the carrier; a high-voltage power supply for supplying a high voltage for generating a potential difference between the carrier and the counter electrode; and a high-voltage power supply disposed between the carrier and the counter electrode. A control electrode comprising: an insulating substrate; a plurality of gates provided on the insulating substrate to pass a developer; and at least one or more electrode groups provided around the plurality of gates. And a first potential state that gives an electric field from the carrier to the gate in which the developer can start moving to the gate according to image data on the individual electrodes of the control electrode; and A plurality of potential states including a third potential state in which no new movement occurs to the gate and no acceleration is applied to the developing agent during movement; and control circuit means capable of applying a plurality of potential states to the electrode group. Control means, and the control circuit controls the electrode Corresponding a predetermined potential to the electrode to control the passage of the gate of the developer by applying the,
In an image forming apparatus for forming an image on the surface of a recording medium conveyed between the control electrode and the counter electrode, the control means needs to apply the first potential state for one pixel. The control is performed for a time longer than the time required for a sufficient amount of the developer to reach the speed at which the gate can reach the gate in the first or third potential state.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an embodiment of a printer equipped with an image forming apparatus according to the present invention, and each element will be outlined with reference to FIG. In the following description, an image forming apparatus having a configuration corresponding to a negatively charged toner will be described in detail. However, when a positively charged toner is used, the polarity of the applied voltage may be appropriately set accordingly. I just need.

As shown in FIG. 2, the printer includes an image forming section 1 having a toner supply section 2 and a printing section. The image forming unit 1 visualizes an image corresponding to an image signal on a sheet as a recording medium using toner as a developer. In other words, the present printer directly forms an image on paper by causing toner to fly and adhere to the paper and controlling the flight of the toner based on an image signal.

On the side where the paper enters the image forming section 1,
A paper feeding device 10 is provided. The paper feeding device 10 includes a paper cassette 4 that stores paper 5 as a recording medium, a pickup roller 6 that sends out the paper 5 from the paper cassette 4, and a paper feed guide 7 that guides the supplied paper 5. Further, the paper feeding device 10 includes a paper feeding sensor (not shown) for detecting that the paper 5 has been supplied. The pickup roller 6 is driven to rotate by a driving device (not shown).

A fixing unit for fixing the toner image formed on the paper 5 in the image forming unit 1 to the paper 5 by heating and pressing the toner image on the paper output side of the paper 5 from the image forming unit 1. 11 are provided. The fixing unit 11 includes a heating roller 12, a heater 13, a pressure roller 14, a temperature sensor 15,
And a temperature control circuit 80. The heating roller 12 is made of, for example, an aluminum tube having a thickness of 2 mm. Heater 13
Is composed of, for example, a halogen lamp and is built in the heating roller 12. The pressure roller 14 is made of, for example, a silicone resin.

The heating roller 12 and the pressure roller 14, which are provided opposite to each other, are provided with springs or the like (not shown) at both ends of each shaft, for example, 2 kg so that the paper 5 can be pressed therebetween. Is applied. The temperature sensor 15 measures the temperature of the surface of the heating roller 12. The temperature control circuit 80 is controlled by the main control unit, controls ON / OFF of the heater 13 based on the measurement result of the temperature sensor 15, and keeps the temperature of the surface of the heating roller 12 at, for example, 150 ° C. Also,
The fixing unit 11 includes a paper discharge sensor (not shown) that detects that the paper 5 has been discharged. Note that the fixing unit 11 may be configured to fix the toner image by heating or pressing the sheet 5.

Although not shown, on the paper output side of the paper from the fixing unit 11, a paper discharge roller for discharging the paper 5 processed by the fixing unit 11 onto a paper discharge tray, and the discharged paper 5 A receiving tray is provided. The above-mentioned heating roller 12, pressure roller 14, and paper discharge roller are rotationally driven by a driving device (not shown).

The toner supply unit 2 of the image forming unit 1 includes a toner storage tank 2 in which a toner 21 as a developer is stored.
0, a toner carrier 22 as a cylindrical carrier (sleeve) for carrying the toner 21 by magnetic force, and a toner storage tank 20 are provided inside, and the toner 21 is charged and an outer periphery of the toner carrier 22 is provided. The doctor blade 23 regulates the thickness of the toner layer carried on the surface. The doctor blade 23 is provided on the upstream side in the rotation direction of the toner carrier 22 so that the distance from the outer peripheral surface of the toner carrier 22 is, for example, 60 μm.
The toner 21 is, for example, a magnetic toner having an average particle diameter of 6 μm.
The charge is applied so as to be 4 μC / g to −5 μC / g.

The toner carrier 22 is driven by a driving device (not shown), and rotates at a speed of, for example, 80 mm / sec on the surface in the direction of arrow A in the figure. The toner carrier 22 is grounded, and magnets (not shown) are arranged inside the toner carrier 22 at a position facing the doctor blade 23 and a position facing a control electrode 26 described later. Thereby, the toner carrier 22
Can carry the toner 21 on its outer peripheral surface. Further, the toner 21 carried on the outer peripheral surface of the toner carrier 22 forms ears at positions corresponding to the above positions on the outer peripheral surface. The toner carrier 22
May be configured to carry toner 21 by electric force or electric force and magnetic force instead of carrying toner 21 by magnetic force.

The printing section of the image forming section 1 has a thickness of, for example, 1 m.
m, an opposing electrode 25 facing the outer peripheral surface of the toner carrier 22, a high-voltage power supply unit 30 for supplying a high voltage to the opposing electrode 25, and a control provided between the toner carrier 22. Electrode 26, static elimination brush 28, static elimination power supply 17 for applying a static elimination potential to static elimination brush 28, paper 5
, A charging power source 18 for applying a charging potential to the charging brush 8, a dielectric belt 24, and cleaner blades 19 for supporting members 16a and 16b supporting the dielectric belt 24. .

The counter electrode 25 is provided such that the distance from the outer peripheral surface of the toner carrier 22 is, for example, 1.1 mm. The dielectric belt 24 is made of PVDF as a base material,
It has a volume resistivity of 10 ¹⁰ Ω · cm and a thickness of 75 μm.
The dielectric belt 24 is driven by a driving device (not shown), and the speed on its surface is, for example, 30 m in the direction of the arrow in the figure.
Rotate at m / sec. Further, a high voltage of, for example, 2.3 kV is applied to the counter electrode 25 by a high voltage power supply unit (control means) 30. That is, an electric field required to cause the toner 21 carried on the toner carrier 22 to fly in the direction of the counter electrode 25 is generated between the counter electrode 25 and the toner carrier 22 by the high voltage applied from the high voltage power supply unit 30. Has been granted.

The neutralization brush 28 is provided on the downstream side of the control electrode 26 in the rotation direction of the dielectric belt 24 so as to be in pressure contact with the dielectric belt 24. The neutralizing brush 28 is applied with a neutralizing potential of 2.5 kV by the neutralizing power source 17 to neutralize unnecessary charges existing on the surface of the dielectric belt 24.

The cleaner blade 19 includes, for example,
When the toner 21 adheres to the surface of the dielectric belt 24 due to an unexpected situation such as a paper jam (paper jam), the toner 21 is removed to prevent the back surface of the paper from being contaminated by the toner 21.

Although not shown, the printer has a main control section which controls the entire printer as a control circuit, an image processing section which converts the obtained image data into a format of image data to be printed, and An image memory for storing image data and an image forming control unit for converting image data obtained from the image processing unit into image data to be given to the control electrode 26 are provided.

The control electrode 26 extends two-dimensionally in parallel with the tangential direction of the surface of the counter electrode 25 and opposed to the counter electrode 25.
The structure allows the toner to pass in five directions. The electric field applied to the surface of the toner carrier 22 changes according to the potential supplied to the control electrode 26, and the flying of the toner 21 from the toner carrier 22 to the counter electrode 25 is controlled.

The control electrode 26 is provided so that the distance from the outer peripheral surface of the toner carrier 22 is, for example, 100 μm, and is fixed by a support member (not shown). As shown in FIG. 3, the control electrode 26 includes an insulating substrate 26a, a high-voltage driver (not shown), and an independent ring-shaped conductor, that is, a ring-shaped electrode 27.

The insulating substrate 26a is made of, for example, a polyimide resin and has a thickness of 25 μm. Further, a hole to be a gate 29 described later is formed in the insulating substrate 26a. The ring-shaped electrode 27 has, for example, a thickness of 1
It is made of a copper foil of 8 μm, provided around the hole, and arranged according to a predetermined arrangement. The opening of each hole has a diameter of, for example, 160 μm, and serves as a passage for the toner 21 flying from the toner carrier 22 to the counter electrode 25. Hereinafter, this passing portion is referred to as a gate 29. In addition, each ring-shaped electrode 27
Is provided with an opening having an opening diameter of 200 μm.
The gate 29, that is, 2560 holes formed in the ring-shaped electrode 27 are formed, for example, and each ring-shaped electrode 27 is controlled by a power supply line 41 and a high-voltage driver (not shown). It is electrically connected to the unit 31.

The surface of the ring-shaped electrode 27 and the surface of the power supply line 41 are covered with an insulator layer (not shown) having a thickness of 30 μm. The insulation between them, the insulation between the ring-shaped electrode 27 and the power supply line 41 that are not connected to each other, and the insulation between the toner carrier 22 and the counter electrode 25 are ensured.

A pulse corresponding to an image signal, that is, a voltage is applied to a ring-shaped electrode 27 of the control electrode 26 by a control power supply unit (control means) 31. That is, the control power supply unit 31
In the case where the toner 21 carried by the toner carrier 22 is allowed to pass through the ring-shaped electrode 27 in the direction of the counter electrode 25 (hereinafter referred to as ON potential), for example, 200 V is applied and not passed (hereinafter referred to as “ON potential”). , OFF potential), for example, 0 V is applied as described later.

As described above, when the potential applied to the control electrode 26 is controlled in accordance with the image signal, and the paper 5 is disposed on the surface of the counter electrode 25 facing the toner carrier 22, the image signal is applied to the surface of the paper 5. Is formed in accordance with. In addition,
The control power supply unit 31 is controlled by a control electrode control signal sent from an image forming control unit (not shown).

The above-mentioned printer can be used not only as a printer for output of a computer or a word processor but also for a print portion of a digital copy. The operation will be described with reference to the flowchart of FIG.

First, for example, when a document to be copied is placed on the image reading section and a copy start button (not shown) is operated, the main control section having received this input starts an image forming operation. That is, a document image is read by the image reading unit (S1), the image data is processed by the image processing unit (S2), and stored in the image memory (S3). The image data stored in the image memory is transferred to the image forming control unit (S4), and the image forming control unit starts converting the input image data into a control electrode control signal to be given to the control electrode 26 (S5). .

When the desired (predetermined amount) of the control electrode control signal is obtained (S6), the image forming control unit rotates the toner carrier 22 by a driving device (not shown) (S6).
7) An OFF potential is applied to the control electrode 26 (S8), and a high voltage is applied by the high voltage power supply 30 and the dielectric belt 24 is driven (S9). Further, the pickup roller 6 shown in FIG.
10) The paper 5 in the paper cassette 4 is sent out toward the image forming unit 1, and the paper feed sensor detects that the paper is in a normal paper feed state (S11).

The sheet 5 sent out by the pickup roller 6 is transported between the charging brush 8 and the supporting member 16. The same potential as that of the counter electrode 25 is applied to the support member 16a by the high-voltage power supply unit 30 (S12). Charging brush 8
, A charging potential of 1.2 kV is applied by the charging power supply 18. The paper 5 is supplied with a charge due to a potential difference between the charging brush 8 and the support member 16a, and is conveyed to the surface of the printing unit of the image forming unit 1 facing the control electrode 26 of the dielectric belt 24 while being electrostatically attracted. The predetermined amount of the control electrode control signal differs depending on the configuration of the printer.

Thereafter, the image forming control unit supplies the control electrode control signal to the control power supply unit 31. The supply of the control electrode control signal is performed at a timing synchronized with the supply of the paper 5 to the printing unit by the charging brush 8. The control power supply unit 31 controls a high voltage applied to each ring-shaped electrode 27 of the control electrode 26 based on the control electrode control signal. That is, a potential of 200 V or 0 V is appropriately applied from the control power supply unit 31 to the predetermined ring-shaped electrode 27, and the electric field near the control electrode 26 is controlled. That is, the control electrode 2
In the gate 29 of No. 6, the prevention of the flight of the toner 21 from the toner carrier 22 to the counter electrode 25 and the release thereof are appropriately performed according to the image data. Thereby, the counter electrode 25
Due to the movement of the dielectric belt 24 on the front surface, a toner image corresponding to the image signal is formed on the paper 5 moving at a speed of 30 mm / sec toward the paper output side.

The paper 5 on which the toner image has been formed is the support member 1
After being separated from the dielectric belt 24 at the curvature of 6b and conveyed to the fixing unit 11, the fixing unit 11 fixes the toner image on the paper 5. Paper 5 with toner image fixed
Is discharged onto a discharge tray by a discharge roller, and normal discharge is detected by a discharge sensor. Based on this detection operation, the main control unit determines whether the printing operation has been normally completed (S13).

By the above image forming operation, a good image is formed on the paper 5. Since the printer directly forms an image on the sheet 5, a visualizing member such as a photoconductor or a dielectric drum used in a conventional image forming apparatus is not required. Therefore, the transfer operation for transferring the image from the visualized object to the sheet 5 is omitted, so that the image does not deteriorate. For this reason, the reliability of the device is improved. In addition, since the configuration of the device is simplified and the number of parts is reduced,
It is possible to reduce the size and cost.

Whether the printer according to the above embodiment is used as a print portion of an output terminal of a computer or a print portion of a digital copy, an image forming operation is performed even though there is a difference in the image signal to be processed and its exchange. The method itself has no differences.

As described above, the toner carrier 22 is grounded, while the counter electrode 25 and the supporting member 16a are applied with a high voltage of 2.3 kV, and the charging brush 8 is applied with a high voltage of 1.2 kV. Therefore, the charging brush 8 and the supporting member 16
a between the charging brush 8 and the dielectric belt 2
Negative charges are supplied to the surface of the sheet 5 transported during the period 4. When a negative charge is supplied, the paper 5 is moved directly below the gate 29 by the movement of the dielectric belt 24 while being attracted to the dielectric belt 24 by the electrostatic force of the charge. The charge on the surface of the dielectric belt 24 is
And the surface potential becomes 2 kV due to the balance with the potential of the counter electrode 25.

In this state, a voltage of 200 V is applied to the ring-shaped electrode 27 of the control electrode 26 by the control power supply 31 so that the toner 21 carried on the toner carrier 22 passes in the direction of the counter electrode 25. Toner 21 is gate 2
9 is not applied, a potential of 0 V is applied. In the state where the paper 5 is attracted to the dielectric belt 24 in this manner,
An image is formed directly on the surface.

Control electrode 2 used in the above embodiment
The configuration of No. 6 will be described. Gate 2 in FIG.
FIG. 5 shows an example of the potential control for the ring-shaped electrode 27-n in the case where the toner 21 is caused to fly only to 9-n.

In the control as shown in FIG. 5, the ON potential is controlled as the first potential state, and the OFF potential is controlled as the second potential state. The potential control is performed as shown in FIG.
According to the N signal, 200 V, which is the ON potential, is switched and applied to the ring-shaped electrode 27-n by the control power supply unit 31, but the image signal is turned off and the potential of the other ring-shaped electrode 27 disposed on the other gate 29. Has the above-mentioned OFF potential applied. During the time period during which the ON potential is applied, a desired electric field is formed between the toner carrier 22 and the toner carrier 22 so that the toner 21 can fly well, and a predetermined amount of the toner 21 flies to obtain good pixels.

In the structure of the above embodiment, the ON potential of the toner 21 on the toner carrier 22 is applied to the control electrode 26 after the ON potential is applied to the control electrode 26.
It has been confirmed from an experiment using a high-speed camera or the like that a time t11 required to pass through is approximately 300 μsec. For example, FIG. 6A schematically shows the state of the flying toner 21 when 150 μsec has elapsed after the ON potential was applied to the toner 21. As described above, the toner 21e in flight flies 150 degrees after the ON potential is applied.
In about μsec, the toner 21 cannot pass through the gate 29. FIG. 6B shows a flying state of the toner 21 250 μsec after the ON potential is applied. Basically, the flying toner 21e is a part of the toner 21 having a high charge amount and present on the surface of the toner 21 layer within 300 μsec after the application of the ON potential, and the flying toner 21e, which started flying relatively early, Some arrive at the gate 29, but most of them have not reached the gate 29 yet, and the toner 21e does not pass through the gate 29.

When the ON potential is switched to the OFF potential in this state, the acceleration electric field acting on the flying toner 21 is released, and it seems that the flying does not occur. But,
Actually, the flying toner 21e has a momentum, and unless the momentum is zero or the direction is reversed, the flying toner 2e
No suspension of 1 occurs. In the present embodiment, the electric field formed when the OFF potential is applied does not have a directional component that applies a force in the direction of the toner carrier 22 to the toner 21, and the OFF potential is applied to the flying toner 21. Even if the voltage is applied, the acceleration of the flying speed decreases, but the flying continues as it is and passes through the gate 29. The electric field between the control electrode 26 and the counter electrode 25 of the toner 21 that has passed through the gate 29 only slightly changes its intensity and does not change its direction. To form an image.

Further, as described above, in this embodiment, the OFF
0 V is applied as a potential. Therefore, when the OFF potential is applied, the electric field formed in the area opposed to the toner carrier 22 and the control electrode 26, inside the gate 29 and around it is O
Although it is much smaller than when the N potential is applied, the electric field component particularly in the direction of the counter electrode 25 does not reverse. Since the electric field formed at the OFF potential is too small to cause the toner 21 to fly from the new toner carrier 22, the toner 21 carried on the toner carrier 22 does not start flying newly, but during the flight, O is applied to the toner 21e.
Even after being switched to the FF potential, an extremely weak electric field of the OFF potential is applied, and the flying toner 21e continues to fly even after the OFF potential is applied without changing its momentum, passes through the gate 29, and passes through the sheet 5. To form an image.

As described above, when the ON potential is applied to the control electrode 26 to the toner 21 carried on the toner carrier 22 to start the flying of the toner 21 and give the initial speed of the flying to the toner 21, the control is immediately performed. Printing is possible even when an OFF potential is applied to the electrode 26. That is, the application time of the ON potential seems to be very short, and it seems that the ON potential in the form of an impulse as shown in FIG. 7 can be used, for example, in correspondence with FIG. FIG. 8 schematically shows the flying state of the toner.
This will be described with reference to FIG.

FIG. 8A shows a state before the ON potential is applied. When an ON potential is applied in this state, a strong electric field is generated in the direction of the counter electrode 25, and the outermost toner 21f exposed to the strong electric field starts flying as shown in FIG. 8B. Immediately after the toner 21f starts flying, the toner 21g of the next layer is not exposed to the strong electric field,
1 g of toner has not been generated, but the toner 2 that has flown first
When 1f has moved to some extent and the toner 21g is exposed to a strong electric field, the toner 21g of the next layer starts to fly as shown in FIG. 8C. As described above, on the surface of the toner 21 layer, the flying starts from the surface toner 21 sequentially, and finally the flying state as shown in FIG. 6 is obtained.

Therefore, with the impulse-shaped ON potential as shown in FIG. 7, there is a possibility that the toner 21f on the outermost surface and the toner 21 in the vicinity thereof may fly, but the toner 21 in the lower layer does not fly, and a dot is formed. Sufficient toner 21 required for cleaning does not fly. If a sufficient amount of the toner 21 required to form one dot does not fly, a blurred image having insufficient diameter of formed dots and insufficient contrast of dot density is obtained. That is, the application of a certain degree of ON potential, that is, the time t1 required for the amount of toner 21 that can form a desired dot to start flying
0 is required. This time depends on the characteristics of the apparatus, that is, the state of layer formation such as the layer thickness, the filling rate, and the transport amount of the 21 toner layers,
It is not particularly limited and may be determined by, for example, an experiment, etc., because it varies depending on characteristics of the toner 21 such as a particle size, a charge amount, and fluidity, and the magnitude and direction of a formed electric field. Is required to start the flight of the toner 21 sufficient for dot formation by applying a voltage of 190 μsec, and a time t11 of passing through the gate 29 is required to be approximately 300 μsec. (In a state where an electric field from the toner carrier 22 to which the toner 21 can start to move to the gate 29 is applied) as an application time T of 250 μm
sec.

As described above, it is desirable to set the ON time, that is, the application time T of the first potential state, to be longer than the above-mentioned t10. For example, paying attention to the toner 21h that has started flying relatively late as shown in FIG.
It is assumed that the ON potential is switched to the OFF potential immediately after the start of flight. Immediately after being switched to the OFF potential, the speed of the toner 21h is not sufficiently accelerated.
In addition, an electric field in the direction of the toner carrier 22 is formed around the toner 21h by the space charge of the toner 21f or 21g that has flew earlier, and the phenomenon that the toner 21 that has started flying once returns to the toner carrier 22 is generated. Occur. Therefore, it is desirable to apply the ON potential for a certain period of time from when the necessary amount of toner 21 starts flying until it reaches a certain speed.

This time is determined by the configuration of the apparatus, for example, the toner 2
The state of layer formation, such as the thickness of one layer, the filling rate, the transport amount, etc., the characteristics of the toner 21 such as the particle size, the charge amount, and the fluidity, the magnitude and direction of the formed electric field, the toner carrier 22 and the control electrode 26
Is not particularly limited and may be appropriately determined by experiments or the like.

As described above, a sufficient amount of toner 21 for forming one dot that has started flying by applying the ON potential.
The time t12 required to accelerate the toner to a certain extent
It has been confirmed from a flight experiment using the present embodiment that the time No. 1 is 220 μsec slightly longer than the time t10 required to start the flight.

As described above, in the present embodiment, the application time T of the ON potential is 250 μsec, that is, t12 <T <t11. Therefore, the time required to form one pixel can be shortened, so that the printing speed of the apparatus can be improved, and the necessary toner 21 flies reliably, so that no image deterioration due to the improvement in printing speed occurs. .

The above times t10, t11, t12
Are the characteristics of the apparatus, that is, the state of layer formation such as the layer thickness, filling rate, and transport amount of the toner 21 layer; In addition, since it is easily changed by various parameters such as a distance between the toner carrier 22 and the gate 29, a position of the counter electrode 25, and a fluid characteristic such as an air resistance generated when the toner 21 flies, there is no particular limitation. It may be determined by or observation.

Further, in the above embodiment, since the toner 21 flies from top to bottom, gravity acts on the flight of the toner 21, and gravity other than the electric field contributes to the acceleration of the toner 21. On the other hand, when the toner 21 flies upward from below as shown in FIG. 10, a separate time must be set because gravity lowers the acceleration of the toner 21. As shown in FIGS. 2 and 10, only the flying direction of the toner 21 changes, and even when other parameters are equal, the above-mentioned t is not affected by the contribution of gravity.
10, 10, 11 and 12 are slightly longer than those in the above-described embodiment, and the above-described t10, t11, and t12 cannot be used as they are, and experiments and observations are repeated to investigate t10, t11, and t12 again, and the first potential state of ON is set. It is necessary to re-set the potential as needed.

In the above embodiment, the necessary toner 21 is used.
The ON potential is applied for a time longer than the time t12 necessary to obtain the speed required for the flight, while the potential is switched as soon as the toner 21 is accelerated to the required speed and the toner 21 is not accelerated more than necessary. Like that. Thus, it is desirable not to apply the ON potential more than necessary to accelerate the toner 21.

FIG. 9 shows the reason. FIG. 9 shows toner 21
Shows the state when the image reaches the surface of the sheet 5. FIG.
Since the toner 21 arriving at the surface of the paper 5 flies at the velocity V as shown in (a), there are toner 21a that rebounds and spreads on the surface of the paper 5 and toner 21b that diffuses on the surface. When the rebound toner 21a or the diffusion toner 21b is generated, the toner becomes flying toner 21d as shown in FIG. 9B, and scatters around the toner 21c constituting the pixel to deteriorate the pixel in the future. For example, if the toner 21d is present around the pixel, the outline of the pixel is blurred by the toner 21d, resulting in a blurred image from which no contrast can be obtained.
If no contrast is obtained in the pixels, not only faithful reproduction of the halftone cannot be obtained, but also in the case of a color image forming apparatus, a problem that it is difficult to reproduce a desired color is newly introduced.

Since the flying toner 21d is caused by the rebound and diffusion of the toner 21, the flying toner 21d can be reduced by lowering the flying speed V of the toner 21, which is a direct cause thereof. Although it is easy to reduce the charge amount of the toner 21 to reduce the flying speed V, it is difficult to simply reduce the charge amount of the toner 21 alone. The charging rate changes at the same time, and the state of the toner 21 layer also changes, and adjustment of the toner supply unit 2 is required, which is not preferable. Further, the time t12 required for sufficiently accelerating the speed of the toner 21 immediately after the start of the flight described above becomes long, which causes a reduction in printing speed and instability of the toner layer, which is not appropriate.

In the above embodiment, the application time of the ON potential is shorter than the time when the toner 21 passes through the gate 29, so that the toner 21 is not accelerated more than necessary between the toner carrier 22 and the gate 29, , The arrival time V of the toner 5 on the surface of the sheet 5 can be minimized, and the flying toner 21d is less likely to be generated, and a good image can be formed.

In the above embodiment, when the OFF potential is applied, the direction of the electric field formed in the area where the toner carrier 22 and the control electrode 26 face each other includes the direction of the counter electrode 25.
1 is not greatly reduced. On the other hand, when the deceleration of the toner 21 is obtained,
The potential is very close to the toner carrier 22 and the counter electrode 25,
That is, the electric field formed when the OFF potential is applied is very small, and the air resistance is very large.
The configuration in which the toner 21 flies upward and cannot be ignored due to the influence of gravity can be used. In this configuration, when the OFF potential is applied, and when the flying toner 21 is present in a region facing the toner carrier 22 and the control electrode 26, an extremely weak electric field is applied to the toner 21 while gravity and air resistance act. Thus, the toner 21 is decelerated.

Further, when deceleration of the toner 21 is necessary, it is desirable that the OFF potential is a potential at which an electric force can be applied to the toner 21 in the direction of the toner carrier 22, for example, a negative potential in the apparatus structure of the above embodiment. However, in another device configuration, for example, when a potential of 100 V is applied to the toner carrier 22, the toner 21 is changed to +50 V.
Even if the polarity is opposite to the above, a potential that forms an electric field that can be decelerated with respect to the toner 21 is considered, and the polarity of the potential is not particularly limited as long as the electric field is formed.

However, if the electric field formed when the OFF potential is applied is too large, that is, the flying toner 21
If the electric field for deceleration is too large, the oppositely charged toner 21 existing in the toner 21 will fly anew, which is not desirable.
It is an essential condition that the oppositely charged toner 21 existing in the toner 21 carried on the surface 2 is weaker than the electric field at which the toner 21 newly starts flying.

In the above configuration, when the OFF potential is, for example, -100 V, that is, even when the configuration other than the OFF potential is based on the same parameters as in FIG.
In a configuration in which the flying toner 21 is decelerated when the potential is applied, that is, in a configuration in which the OFF potential, which is the third potential state, is applied, t20, t21, and t22 correspond to the above-described t10, t11, and t12. From experiments and observations, 1
90, 330 and 250 μsec.

This will be described with reference to FIG. 8, for example, when the ON potential is applied from the state of FIG. 8A until the predetermined amount of toner 21 starts to fly, the same ON potential as in FIG. The time t20 is 190 μs, which is the same as the time t10, since the other parameters are the same as those shown in FIG.
ec. However, as in the case of the toner 21h in FIG. 8D, the switching to the OFF potential occurs immediately after the flight starts relatively late, and the force in the direction of the toner carrier 22 from the electric field formed by the OFF potential is applied to the toner 21h. Is applied, and the toner 21h is decelerated. When the speed of the toner 21h is insufficient, the toner 21h returns to the toner carrier 22 and does not fly.

For this reason, the above-mentioned problem occurs because the flying amount of the toner 21 is insufficient and the toner amount is insufficient. Therefore, it is necessary to sufficiently accelerate the speed of the toner 21h by the electric field due to the ON potential so that the toner 21h can reach the gate 29 even when the deceleration electric field is applied at the OFF potential to the toner 21h until the OFF potential is applied. There is.

For this reason, the ON potential is applied longer than the time T given in FIG. 2 so that the flying direction of the flying toner 21 does not reverse even when the toner is switched to the OFF potential. Good. Therefore, it is desirable that the application time T of the first potential state is, for example, T = 300 μsec such that t22 <T <t21.

The configuration in which the toner 21 is decelerated when the OFF potential is applied is not limited to the case where a potential that forms a deceleration electric field is used as the OFF potential as described above. For example, as shown in FIG. For example, there is a case where the gravity of the toner 21 cannot be ignored, for example, a case where the weight of the toner 21 particles is very heavy. In addition, in the configuration shown in FIGS. 2 and 10, for example, as shown in FIGS.
When the direction of the force applied by the electric field formed when the FF potential is applied has a component in the direction of the counter electrode 25 similarly to the force applied when the ON potential is applied, the particle size of the toner 21 is large and the air resistance is low. If it is large, the toner 21 can be easily decelerated.

In the above embodiment, the flight control of the gate 21 has been described in the case of the control electrode 26 by a single drive in which each gate 29 is controlled by one electrode.
The present invention can be similarly applied to the case where the control electrodes 26 based on the matrix control as shown in FIG. 11 are used, and a large amount of images can be formed. In FIG. 11, band electrodes 27a and 27b are arranged instead of the ring electrodes 27. A band-like electrode 27b is arranged on the toner carrier 22 side of the control electrode 26,
The configuration is such that a strip electrode 27a is arranged on the side of the counter electrode 25. Further, the potential control as described above is performed by using the strip-shaped electrode 27.
b, or may be performed on the strip electrodes 27a, or may be performed on both of the strip electrodes 27a and 27b. The above-described control is efficiently performed on the strip electrodes 27b close to the toner carrier 22, but is most preferably performed on the strip electrodes 27a and 27b.

Further, in FIG. 3 and FIG. 11, only the electrodes for directly controlling the flight control of the toner 21 are arranged on the control electrode 26, but a plurality of electrodes are provided on the toner carrier 22 side, the counter electrode 25 side or both sides. The present invention can be favorably applied to a configuration having a shield electrode composed of a single or a plurality of electrode plates disposed for the ring-shaped electrode 27 or the strip-shaped electrode.

Further, in the above embodiment, as shown in FIG.
Although a square wave with one pulse is applied to form one dot as the potential state, the pulse required for forming one dot is not limited to this, and may be composed of a plurality of square waves, for example.

In FIG. 2, a waveform as shown in FIG. 13 can be used as the ON potential. As shown in FIG. 13, the ON potential is composed of a plurality of (four in FIG. 13) minute square pulses, and the ON potential includes a first potential state and a second potential state. When the ON potential is constituted by such a plurality of pulse trains, for example, the flying start of the toner 21 from the surface of the toner 21 layer occurs at HIGH, but the flying start of the toner 21 does not occur in a LOW portion. In particular, HIGH
At the moment of switching from the state to the LOW state, in addition to the toner 21 flying toward the gate 29, the toner 21h shown in FIG.
Such a phenomenon as to start flying once but return to the toner carrier 22 occurs, and this is repeated for each minute pulse. Therefore, the time required to fly the amount of toner 21 required to form one dot is longer than the time T in FIG. 2 or FIG.

In the pulse application as shown in FIG. 5, the application time of the first potential state is equal to the application time of the ON potential, but in the pulse shown in FIG. 13, the minute pulse T1 = 70 μsec.
Therefore, as the first potential state, T = 70 × 4 = 28
When 0 μsec is applied to the toner 21 when the ON potential is applied, the ON potential T0 is 370 μsec.
In such a control, the application time T of the first potential state and the ON potential application time T0 are not equal. However, even in the control having such a vibration component, the OF 21 is shorter than the time required for the toner 21 to pass through the gate 29, and after the necessary speed is obtained at which the toner 21 can pass through the gate 29.
It is preferable to control the first potential state so as to apply the F potential.

In addition to the case where the toner 21 is decelerated when the OFF potential is applied, that is, the case where the third potential is applied, the LOW portion of the ON potential is applied to the toner 21. When deceleration is applied, that is, when the third potential is applied, the first
It is necessary to adjust the application time of the potential state.

In addition to such control, for example, application by various waveforms such as a triangular wave, a sine wave, or a case composed of a plurality of impulse trains is not limited to a square wave as shown in FIG. Further, in the above-described embodiment, the DC potential is used as the first and second potential states. However, the present invention is not limited to this, and the AC potential is superimposed on the AC potential or the DC potential as one or both potential states. It may be a potential.

FIG. 14 shows an example. FIG.
Indicates a case where a triangular wave is used as the ON potential. FIG.
In a waveform having a vibration component whose applied potential changes with time starting from a triangular wave as described above, the first potential state is determined by the threshold value of the potential at which the toner 21 starts flying.

In the above embodiment, it is previously determined that the threshold value of the potential applied to the ring-shaped electrode 27 and the potential at which the toner 21 starts flying is 75V. Therefore, as shown in FIG. 14, a state where a potential exceeding 75 V is applied, the shaded portion in FIG. 14 corresponds to the first potential state, and a positive potential other than the shaded portion is shown. That is, the area where the toner 21 does not start flying newly but does not decelerate the toner 21 is the second potential state, and the area where the toner 21 is negative and the toner 21 can be decelerated is the third potential state, An area T2 exceeding 75 V in one cycle of the triangular wave is 35 μsec,
Since there are nine triangular waves at the ON potential, the application time T of the first potential state in FIG. 14 is T = 35 × 9 = 3.
15 μsec.

As described above, when there is a time region that has a vibration component as the ON potential and does not contribute to the flight of the toner 21, the application time of the ON potential is inevitably lengthened and the printing speed is reduced. I do. However, in the control having such a vibration component, the threshold value of the potential for causing the toner 21 to fly becomes lower than that of the control using only DC. Therefore, the withstand voltage of the potential switching means is reduced, and the cost can be reduced. Effective. Even when such a control is used, the OFF potential is applied so that the time required for the toner 21 to pass through the gate 29 is shorter than the time required for the toner 21 to pass through the gate 29, and after the necessary speed at which the toner 21 can pass through the gate 29 is obtained. It is preferable to control the first potential state, so that a reduction in printing speed due to the application of a potential having a vibration component can be minimized, and a good image can be obtained by minimizing scattering of the toner 21. A forming operation can be obtained.

The problem caused by the scattering of the toner 21 has been described with reference to the case of a black-and-white image forming apparatus as an example, but appears more prominently in the case of a color image forming apparatus. The color image forming apparatus includes, for example, an image forming unit including a plurality of toner supply units and a printing unit corresponding to each color, and a color toner, for example, as shown in FIG. A color image forming apparatus using magenta, magenta, cyan, and black may be formed. In FIG. 12, the colors correspond to yellow, magenta, cyan, and black, respectively.
The image forming units 1a, 1b, 1c, 1d according to the present invention are arranged, and a color image is formed based on color image data.

Other components may be the same as those in FIG. According to the present invention, the printing speed is improved and the scattering toner 21 is improved.
Can be performed at the same time, and the above problem does not occur at all, so that desired color reproduction and good color image formation can be obtained.

In the above control, the first potential state, the second potential state, and the third potential state are configured to give a constant potential or a potential state.
It is also possible to provide a means for detecting or judging the life of the toner supply unit 1 or the toner supply unit 2 or continuous printing, and to variably control these values based on the judgment.

In the present embodiment, the case where the developer is a toner has been described as an example, but the developer may be an ink or the like. Further, the configuration of the toner supply unit 2 may be a configuration to which an ion flow method is applied. That is, the image forming unit may be configured to include an ion source such as a corona charger. In this case, the same operation and effect as described above can be obtained.

In the present embodiment, the developer may be an ion or the like. The image forming apparatus according to the present invention can be suitably applied to, for example, a printing unit of a digital copying machine and a facsimile machine, a digital printer, a plotter, and the like.

[0086]

According to the image forming apparatus of the first aspect,
Since the application time of the first potential state is controlled to be shorter than the time required for the developer to pass through the gate, the printing time per pixel can be reduced and the printing speed of the apparatus can be improved.
At this time, since the characteristics of the developer and the printing potential value are not controlled, the configuration of the developer supply unit for controlling the characteristics of the developer and the state of layer formation and the circuit configuration of the power supply and the switching means of the potential are changed. Since it is unnecessary, the number of parts can be minimized, and the size of the apparatus can be reduced, the cost can be reduced, and the reliability can be improved. Furthermore, since the developing agent that is flying between the carrier and the gate is not given an excessive speed,
The speed at which the developer reaches the recording medium is kept low,
The developer can be prevented from scattering when the developer reaches the recording medium, and a good image can be obtained. In addition, at this time, since the characteristics of the developer and the applied potential are not controlled, the configuration of the developer supply unit for controlling the characteristics of the developer and the state of layer formation and the circuit configuration of the power supply and the switching means of the potential are changed. Since it is unnecessary, the number of parts can be minimized, and the size of the apparatus can be reduced, the cost can be reduced, and the reliability can be improved.

According to the image forming apparatus of the present invention, the application time of the first potential state is set to the speed required for the amount of the developer necessary for forming one pixel to pass through the gate. After that, the necessary developer is surely flown, so that a good image can be formed without insufficiency of the dot diameter or reduction of the dot density.

According to the image forming apparatus of the third aspect, the application time of the first potential state is controlled to be shorter than the time for the developer to pass through the gate, so that the printing time per pixel is reduced. Printing speed can be improved. At this time, since the characteristics of the developer and the printing potential value are not controlled,
Since the configuration of the developer supply unit for controlling the properties of the developer and the state of layer formation and the circuit configuration of the power supply and potential switching means are unnecessary, the number of parts can be minimized, and , The cost can be reduced, and the reliability can be improved. Further, since the developing agent that is flying between the carrier and the gate is not given an excessive speed, the speed at which the developing agent reaches the recording medium is suppressed, and the recording of the developing agent is performed. The developer is prevented from being scattered when reaching the medium, and a good image can be obtained. In addition, at this time, since the characteristics of the developer and the applied potential are not controlled, the configuration of the developer supply unit for controlling the characteristics of the developer and the state of layer formation and the circuit configuration of the power supply and the switching means of the potential are changed. Since it is unnecessary, the number of parts can be minimized, and the size of the apparatus can be reduced, the cost can be reduced, and the reliability can be improved.

According to the image forming apparatus of the present invention, the application time of the first potential state is set to a speed required for an amount of the developing agent necessary for forming one pixel to pass through the gate. After that, the necessary developer is surely flown, so that a good image can be formed without insufficiency of the dot diameter or reduction of the dot density.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a printer which is an image forming apparatus of the present invention.

FIG. 2 is a schematic sectional view showing a main part of FIG.

FIG. 3 is a plan view showing a control electrode of FIG. 2;

FIG. 4 is a flowchart illustrating a printing operation of the printer in FIG. 2;

FIG. 5 is a waveform diagram showing a pulse waveform of an ON potential of the printer of FIG. 2;

6A and 6B are diagrams illustrating a flying state of the toner, FIG. 6A is an explanatory diagram illustrating a state of the flying toner when 150 μsec has elapsed since the ON potential was applied to the control electrode, and FIG.
FIG. 9 is an explanatory diagram illustrating a state of flying toner at a time point when 250 μsec has elapsed after application of an N potential.

FIG. 7 is a waveform chart showing a case where an ON potential applied to a control electrode is inappropriate.

FIGS. 8A and 8B are diagrams illustrating a flying state of the toner, FIG. 8A is a diagram illustrating a state before an ON potential is applied to a control electrode, and FIG. FIG. 7C is an explanatory diagram showing a state in which the toner of the next layer has started flying, and FIG. 7D is an explanatory diagram showing a flying state of the toner thereafter.

FIG. 9 shows a flying state of the toner on the recording medium,
FIG. 7A is an explanatory diagram illustrating a state in which the toner rebounds and diffuses on the surface of the recording medium, and FIG. 7B is an explanatory diagram illustrating a state in which the rebound toner adheres to the surface of the recording medium.

FIG. 10 is a schematic cross-sectional view illustrating a main part of another embodiment of the printer that is the image forming apparatus of the present invention.

FIG. 11 is a plan view showing a control electrode of FIG. 10;

FIG. 12 is a schematic cross-sectional view illustrating a main part of still another embodiment of the printer that is the image forming apparatus of the present invention.

FIG. 13 is a waveform diagram showing a pulse waveform of an ON potential of a printer according to another embodiment.

FIG. 14 is a waveform diagram showing a pulse waveform of an ON potential of a printer according to still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming part 2 Toner supply part 5 Paper 20 Toner storage tank 21 Toner 22 Toner carrier 25 Counter electrode 26 Control electrode 26a Insulating substrate 27 Ring electrode 29 Gate 30 High voltage power supply part 31 Control power supply part

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Shiro Narukawa 22-22, Nagaikecho, Abeno-ku, Osaka, Osaka Inside (72) Inventor Yukito Nishio 22-22, Nagaikecho, Abeno-ku, Osaka, Osaka (72) Inventor Daisaku Imaizumi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka

Claims (4)

[Claims] 1. A supply means having a carrier for carrying a developer of at least one color, a counter electrode arranged opposite to the carrier, and a high voltage for generating a potential difference between the carrier and the counter electrode. High-voltage power supply means for supplying a voltage, an insulating substrate disposed between the carrier and the counter electrode, and a plurality of gates provided on the insulating substrate as passing portions of the developer, A control electrode comprising at least one or more electrode groups provided around the plurality of gates, and the developer is transferred from the carrier to the gate according to image data on each of the control electrodes. A first potential state that provides an electric field capable of starting movement, and a second potential that does not cause a new movement of the developer from the carrier to the gate and does not decelerate the developer during movement. State can be applied to the above electrode group Control means comprising control circuit means, and the control means controls the passage of the developer through the gate by applying a predetermined potential to a corresponding electrode of the electrode group. In an image forming apparatus for forming an image on a surface of a recording medium conveyed between opposed electrodes, the control means sets an application time of the first potential state to an amount of the visualized image necessary to form one pixel. An image forming apparatus, wherein the agent is controlled to a time shorter than a time required for the agent to pass through the gate in a state where the first or second potential state is applied. 2. A supply means having a carrier for carrying a developer of at least one color, a counter electrode arranged opposite to the carrier, and a high voltage for generating a potential difference between the carrier and the counter electrode. High-voltage power supply means for supplying a voltage, an insulating substrate disposed between the carrier and the counter electrode, and a plurality of gates provided on the insulating substrate as passing portions of the developer, A control electrode including at least one or more electrode groups provided around the plurality of gates; and moving from the carrier to the gate according to image data for each of the control electrodes. And a second potential state in which the developer does not cause a new movement from the carrier to the gate and does not decelerate the moving developer. Control circuit that can apply the potential state of And a control means comprising a step, wherein the control means controls the passage of the developer through the gate by applying a predetermined potential to a corresponding electrode of the electrode group, and the control electrode and the counter electrode In the image forming apparatus for forming an image on the surface of the recording medium conveyed during the period, the control unit may set the application time of the first potential state to 1
The amount of the developer required to form a pixel is equal to the amount of the first developer.
Alternatively, the image forming apparatus is characterized in that the control is performed for a time longer than a time required to reach a speed at which the gate can be reached in the second potential state. 3. A supply means having a carrier for carrying a developer of at least one color, a counter electrode disposed opposite to the carrier, and a high voltage for generating a potential difference between the carrier and the counter electrode. High-voltage power supply means for supplying a voltage, an insulating substrate disposed between the carrier and the counter electrode, and a plurality of gates provided on the insulating substrate as passing portions of the developer, A control electrode comprising at least one or more electrode groups provided around the plurality of gates, and the developer is transferred from the carrier to the gate according to image data on each of the control electrodes. A first potential state that provides an electric field capable of starting movement, and a third state in which the developer does not cause any new movement of the developer from the carrier to the gate and does not accelerate the developer during movement. A plurality of potential states including the potential state of Control means comprising a control circuit means capable of controlling the passage of the developer through the gate by applying a predetermined potential to a corresponding electrode of the electrode group by the control means; And an image forming apparatus for forming an image on the surface of a recording medium conveyed between the counter electrode and the counter electrode, wherein the control unit sets the application time of the first potential state to 1
The amount of the developer required to form a pixel is equal to the amount of the first developer.
Alternatively, the image forming apparatus is characterized in that in a state where the third potential state is applied, control is performed for a time shorter than a time required to pass from the state where the carrier is carried to the gate. 4. A supply means having a carrier for carrying a developer of at least one color, a counter electrode disposed opposite to the carrier, and a high voltage for generating a potential difference between the carrier and the counter electrode. High-voltage power supply means for supplying a voltage, an insulating substrate disposed between the carrier and the counter electrode, and a plurality of gates provided on the insulating substrate as passing portions of the developer, A control electrode comprising at least one or more electrode groups provided around the plurality of gates, and the developer is transferred from the carrier to the gate according to image data on each of the control electrodes. A first potential state that provides an electric field capable of starting movement, and a third state in which the developer does not cause any new movement of the developer from the carrier to the gate and does not accelerate the developer during movement. A plurality of potential states including the potential state of Control means comprising a control circuit means capable of controlling the passage of the developer through the gate by applying a predetermined potential to a corresponding electrode of the electrode group by the control circuit; And an image forming apparatus for forming an image on the surface of a recording medium conveyed between the counter electrode and the counter electrode, wherein the control unit sets the application time of the first potential state to 1
The amount of the developer required to form a pixel is equal to the amount of the first developer.
Alternatively, the image forming apparatus is characterized in that the control is performed for a time longer than a time required to reach a speed at which the gate can be reached in the third potential state.