JPH09207376A - Image forming device - Google Patents

Abstract

(57) [Abstract] (Correction) [Problem] When electrostatically attracting a recording paper to a dielectric belt that is driven to travel and carrying the recording paper, various problems due to a defective conveyance due to the inability to uniformly charge the recording paper may occur. Occurs. SOLUTION: A control electrode 26 for controlling the flight of toner is arranged between a toner carrier 22 and a counter electrode 25. The gate 2 formed on the control electrode 26 to which the toner flies
By applying a potential for flying toner or a potential not flying for toner to the ring-shaped electrode 27 provided around the electrode 9 through the control power supply unit 31 during image formation, the counter electrode 25 is electrostatically attracted to the dielectric belt 24. An image is formed on the formed recording paper 5 with toner. Before being conveyed to the image forming area, the recording paper 5 is supplied with the power supply means 18 via the charge supply roller 33 driven by the drive motor 34 at the same speed as the recording paper is conveyed.
Is charged and charged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a main body of a printing section of a digital copying machine and a facsimile machine, a digital printer, a plotter, etc., and an image is recorded on a recording medium such as a recording paper by flying visible particles. The present invention relates to an image forming apparatus that directly forms a sheet.

[0002]

2. Description of the Related Art In recent years, as an image forming apparatus for outputting a visible image on a recording medium such as recording paper in accordance with an image signal, for example, toner, which is visualized particles, is directly attached to the recording medium. An image forming apparatus for directly forming a toner image on a recording medium has been proposed, for example, in Japanese Patent Application Laid-Open No. 6-155798. In addition, the present inventor has proposed in Japanese Patent Application No. 7-291481 a configuration in which a recording paper, which is a recording medium, is conveyed to an area where an image is formed by a belt.

A conventional image recording apparatus disclosed in the above-mentioned Japanese Laid-Open Patent Publication will be described with reference to FIG. 5. An image forming section 51 having a toner supply section 52 and a printing section 53 is provided. Toner 7 carried on 52
1 is selectively ejected and attached to a sheet-like recording paper 55 which is a recording medium. At this time, by controlling the flight of the toner 71 in accordance with the image signal, a visible image is formed by selectively adhering the toner directly on the recording paper 55.

The toner supply section 52 is composed of, for example, a toner storage section 70 that stores toner 71 as negatively charged developing particles, and a toner carrier 72 that supports the toner 71 by, for example, magnetic force. ing. The toner carrier 72 is grounded, and is rotationally driven in the direction of arrow E in the figure at a surface speed of, for example, 30 mm / sec. The toner 71 is a magnetic toner having an average particle diameter of 10 μm, and has a charge amount of −4 μC / g or less according to a known technique.
The electric charge is applied so as to be −5 μC / g. The toner 71 has an average thickness of 80 on the outer peripheral surface of the toner carrier 72.
It is carried with a thickness of about μm.

[0005] The printing unit 53 constituting the image forming unit 51 includes:
Counter electrode 7 made of an aluminum tube having a thickness of about 2 mm
5 and a control electrode 76 provided between the counter electrode 75 and the toner carrier 72. The counter electrode 75 has a distance of 1 from the outer peripheral surface of the toner carrier 72.
They are arranged with a distance of about mm. Counter electrode 75
Is supplied with a high voltage of, for example, 2.3 kV by the DC power supply unit 80. That is, an electric field necessary for causing the toner 71 carried by the toner carrier 72 to fly in the direction of the counter electrode 75 is applied between the opposite electrode 75 and the toner carrier 72.

A dielectric belt 73 is movably provided on the counter electrode 75 so as to be in contact with the surface of the electrode 75. The dielectric belt 73 is endless (endless)
And is stretched between at least two support rollers 73a and 73b. When the support roller 73a is driven, it is driven to travel in the arrow F direction. Further, in order to electrostatically attract and convey the recording paper 55 to the dielectric belt 73, the dielectric belt 73 is interposed via the recording paper 55.
The charge supply roller 74 that is in contact with the recording paper 55 is disposed on the upstream side in the transport direction of the recording paper.
A charging power source 82 is provided for applying a predetermined charge to the dielectric belt 73 for adsorption.

Then, the charging power supply 82 supplies a high voltage of, for example, 1 kV to the charge supply roller 74, so that the recording paper 55 is supplied to the counter electrode 75 for 2.3 k.
Due to the relationship of V, negative charges are injected, electrostatically attracted to the dielectric belt 73, and conveyed to the area of the printing unit 53 according to the traveling speed of the dielectric belt 73.

The control electrode 76 is parallel to the surface of the counter electrode 75 and is two-dimensionally spread so as to face the counter electrode 75, and the toner flow from the toner carrier 72 to the counter electrode 75 can pass therethrough. It has a simple structure. The electric field applied to the control electrode 76 changes the electric field applied between the toner carrier 72 and the counter electrode 75,
The flight of the toner 71 from the toner carrier 72 to the counter electrode 75 is controlled.

The control electrode 76 is arranged so that the distance from the outer peripheral surface of the toner carrier 72 is, for example, 100 μm. The control electrode 76 includes a flexible printed circuit board (FPC) 76a having a thickness of 50 μm, and a ring-shaped electrode 77 made of a copper foil having a thickness of about 20 μm.
Consists of Gates 79 ... With a diameter of about 150 .mu.m serving as a passage portion of the toner 71 are formed on the substrate 76a, and the ring electrodes 77 ... Are provided around these gates 79. Each of the ring-shaped electrodes 77 is electrically connected to a control power supply unit 81 via a power supply line and a high-voltage driver (neither is shown).

As shown in detail in FIG. 6, the control power source section 81 includes a first power source 83 for applying a potential of 150 V to the ring electrode 77 for allowing the toner 71 to pass through the gate 79, and the toner 71. A second power source 84 that gives a potential of, for example, -200 V that cannot pass through the gate 79, a pull-up resistor 85, a field effect transistor (FET) 86 that is a voltage switching means, and an image signal that supplies an image signal to the transistor 86. And a control circuit 87. When the normal FET 86 is turned on in response to a signal from the image signal control circuit 87, the ring electrode 77 has a potential (the potential for preventing the toner 71 carried by the toner carrier 72 from passing through the second power source 84). -200V) is applied. On the other hand, the image signal control circuit 87 causes the FET 86
When the switch is turned off, the first
By applying a potential of, for example, 150 V with the power supply 83, the toner 71 can be made to fly to the recording paper on the counter electrode side via the gate 79 of the ring electrode 77.

As described above, the potential corresponding to the image signal is applied to the ring-shaped electrodes 77 ... That is, when the control power supply unit 81 causes the ring-shaped electrodes 77 ... To pass the toner 71 carried by the toner carrier 72 toward the counter electrode 75,
A potential of 0 V is applied for about 300 μsec, and a potential of −200 V is applied when the potential cannot pass.
In this way, by selectively controlling the application of the above-mentioned potential to the ring-shaped electrodes 77 ... According to the image signal, the toner is selectively ejected to form a visible image on the recording paper 55 according to the image signal. Can be formed directly.

Here, when the image forming operation is performed, the rotation of the toner carrier 72, the rotation of the counter electrode 75, the application of a potential that does not allow the toner 71 to pass through to the control electrode 76, and the application of the high voltage to the counter electrode are performed. It is applied almost simultaneously by a single trigger.

[0013]

In the above-mentioned conventional image forming apparatus, the recording paper 55 is the control electrode 76 of the printing section 53.
In the image forming area facing the gate 79, the dielectric belt 73 is provided as described above in order to prevent it from floating, and the dielectric belt 73 is charged with the recording paper 55 to electrostatically adsorb it. There is. As a result, the recording paper 55 is accurately conveyed and stable image formation is possible.

However, in order to convey the recording paper 55 by being attracted to the dielectric belt 73, it is necessary to charge the recording paper 55, and this charging is performed using the charge supply roller 74. The charge supply roller 74 is in pressure contact with the dielectric belt 73 and is driven by the running of the dielectric belt 73. Therefore, when forming an image on an envelope, thick paper, or narrow paper, the roller 74 does not rotate,
Diagonal feeding or slippage with the paper occurs and the recording paper 5
5 cannot be conveyed.

When the recording paper 55 slips, the recording paper 5
The image forming operation is started before a desired position of 5, for example, the leading end portion reaches the image forming area, and it becomes impossible to form an image at a predetermined position of the recording paper 55, or the dielectric belt 7
The toner directly reaches the front surface of the recording paper 55, and the rear surface of the recording paper 55 is soiled. Further, there is a case where an oblique feed occurs due to slippage, which causes the image to protrude from the area of the recording paper 55, and as described above, the toner adheres to the dielectric belt 73 and the back surface of the recording paper 55 becomes dirty. Occurs.

When the recording paper 55 slips, the conveying speed of the recording paper 55 decreases, and the recording paper 55 reaches the image forming position.
Takes longer than a predetermined time to reach. Therefore, the charge on the surface of the recording paper 55 is attenuated, the surface potential of the recording paper 55 changes from the desired potential, and the electric charge necessary for electrostatic attraction of the recording paper 55 cannot be obtained. Also, due to slippage, the recording paper 55
The entire surface cannot be uniformly charged, uneven charging occurs, electrostatic attraction is performed on the dielectric belt 73, and the recording paper 55 cannot be accurately conveyed.

Moreover, since the surface potential of the recording paper 55 is not a desired value, the electric field between the toner carrier 72 and the counter electrode 75 becomes improper, and accurate toner flight control becomes difficult. Therefore, image deterioration and image formation failure occur,
In the worst case, image formation cannot be performed.

If the recording paper 55 is normally conveyed, that is, if it is not conveyed at the same speed as the traveling speed of the dielectric belt 73, the contact time of the recording paper 55 with the charge supply roller 74 changes, Accurate transfer of charges will not be performed either. Therefore, it is not possible to impart a uniform charge amount to the recording paper 55, which causes a cause of image quality failure as described above.

In addition, the recording paper 55 is the dielectric belt 24.
When the slip occurs on the recording paper 55 and the dielectric belt 7,
The local distance to 3 may temporarily increase, and peeling discharge may occur. The peeling discharge does not occur uniformly on the surface of the recording paper 55, but occurs locally and irregularly. Therefore, the surface potential becomes uneven on the surface of the recording paper 55, and thus the above-mentioned problems occur. It will be noticeable.

As described above, when an image is formed in a state where the charging potential of the recording paper 55 is non-uniform, it appears as a granular pattern, which causes problems such as deterioration of the image and defective printing, and the above-mentioned problems. Also occurs.

On the other hand, in the control electrode 77 for controlling the toner flight, when the number of gates 79 for forming one line is provided on one line, the image forming area thereof, particularly the conveying direction of the recording paper 55, is formed. The width at is very short. However, it is very difficult to form all the gates 79 on one line, and a potential for controlling the toner flying is supplied to the ring-shaped electrodes 77, ... It is necessary to provide as many circuits as shown in FIG. That is, the driver circuit for applying the voltage for controlling the toner flying becomes complicated, and the cost also increases.

In order to solve such a problem, the gate 79 is arranged in a matrix state, and the flight control of the toner passing through the gate is matrix-driven, so that the driver as shown in FIG. 6 for the toner flight control. The number of circuits is reduced and the formation of the gate 79 is facilitated. However, if such a control electrode 76 is arranged, the recording paper 55
The width of the paper in the carrying direction becomes very long. Therefore, the recording paper 5
It is important that 5 is accurately adsorbed on the dielectric belt 73 to be conveyed.

Moreover, in order to improve the resolution, it is necessary to increase the number of gates 79 formed on the control electrode 76, so that the control electrode 76 is further lengthened in the recording paper 55 conveyance direction. As a result, it is necessary to lengthen the time for adhering the recording paper 55 to the dielectric belt 73.

In addition, in the case of forming a color image using color toners, it is necessary to have respective carriers 72 carrying yellow, magenta, cyan, and black image-forming particles, and a control electrode corresponding thereto is required. 76 are provided respectively. Therefore, in transporting the recording paper 55, it is necessary to pass through the image forming area of the color toner carrier 72, which is the visualized particle of each color, so that the time for passing through the image forming area of each color becomes long and the recording paper The time for surely adsorbing 55 to the dielectric belt 73 and performing accurate conveyance also becomes long.

As described above, the time for adsorbing the recording paper 55 to the dielectric belt 73 and conveying the recording paper 55 becomes long, and as described above, the image forming failure occurs due to the uneven charge applied to the recording paper 55. As the distance passing through the control electrode 76 becomes longer, the image forming defect becomes more remarkable according to the conventional conveying method.

Therefore, in order to stabilize the adsorption state of the recording paper 55 to the dielectric belt 73, a method of increasing the pressing force of the charge supply roller 74 can be considered. However, this also causes deformation of the roller 74, which makes long-term use impossible. Further, when the pressure contact force of the roller becomes strong, the driving torque of the support roller 73b for running the dielectric belt 73 becomes large, and the cost of the motor and the motor power source is inevitably increased.

Further, in order to eliminate the shift of the image forming position due to the slip of the recording paper 55 due to the suction failure of the dielectric belt 73, the recording is performed between the charge supply roller 74 and the image forming area in which the gate 79 is formed. The start of image formation may be controlled by arranging the front edge detection sensor of the paper 55. However, it is very difficult to provide the detection sensor between the roller 73 and the image forming area, and the increase in cost due to the provision of the detection sensor cannot be avoided.

As described above, in the related art, the charge supply roller 74 is constructed so as to simply contact the dielectric belt 73 and rotate in order to impart an electric charge to the recording paper 55, and the recording paper 55 is placed on the dielectric belt 73. Since the recording paper 55 is adsorbed and conveyed to the image forming area, the amount of electric charge applied to the recording paper 55 becomes unstable and causes a conveyance failure due to slippage. As a result, not only a defect due to the partial lifting of the recording paper 55 and a defective image formation occur, but also accurate flight control of toner becomes difficult, and an image formation is impossible.

Therefore, in order to increase the force of electrostatically attracting the recording paper 55 to the dielectric belt 73 and not only the conveyance failure but also the amount of electric charge to be applied, the voltage supplied to the electric charge supply roller 74 is set. It is possible to raise the value. At this time, since the charge amount of the recording paper 55 increases, peeling discharge occurs when the recording paper 55 is peeled from the dielectric belt 73. After the image is formed on the recording paper 55 by this discharge, the formed unfixed image is scattered and disturbs the formed image.

In view of the above-mentioned various problems, the present invention ensures that the recording paper is electrostatically attracted to the dielectric belt to prevent the recording paper from floating on the dielectric belt. The purpose is to make the amount of charge applied uniform.

In particular, an object of the present invention is to reliably perform electrostatic attraction to the dielectric belt for stabilizing the conveyance of the recording paper, and at the same time, to eliminate defective image formation.

[0032]

According to an aspect of the present invention, there is provided an image forming apparatus comprising: a carrier for supporting visualized particles; a counter electrode disposed to face the carrier;
A control electrode having a plurality of gates which are arranged between the carrier and the counter electrode and serve as a passage portion for the visualized particles, and a recording medium on which the image is formed by the visualized particles conveyed on the counter electrode. And applying a potential that causes a predetermined potential difference between the carrier and the counter electrode, and controlling the passage of the visualized particles through the gate by changing the potential applied to the control electrode. In an image forming apparatus comprising: a control unit that forms an image on a recording medium that is conveyed, an endless dielectric belt that is fed along the counter electrode, and a plurality of stretching the dielectric belt. Belt driving means including at least one roller and driving the roller and the dielectric belt through the recording medium before the image formation, and the recording medium faces the control electrode. And a roller member that is driven to rotate in the conveying direction, and a predetermined potential is applied to the roller member in order to impart the same polarity as the visualized particles to the recording medium and electrostatically attract it to the dielectric belt to convey the recording medium. And a power supply unit for applying the power supply.

With the above-described structure, the recording medium is pressed against the dielectric belt without slippage because the roller member is rotationally driven along the conveying direction of the recording medium. Therefore, various problems caused by the slip of the recording medium are eliminated.

Therefore, if the roller member is rotationally driven at the same speed as the conveying speed of the recording medium, the recording medium is surely conveyed without being obstructed when traveling by the dielectric belt. To be done. In particular, at the same time when the roller member is pressed into contact with the roller member, a predetermined charge is applied at this time, and electrostatic attraction with the dielectric belt is compensated for, thereby stabilizing the conveyance. Also, since the roller member is driven to rotate,
Since the pressure contact force to the recording medium is also constant, the charge amount is stable, and the conveyance state in the suction state is also stable.

Further, since the roller member is provided so as to be in pressure contact with one of the downstream support rollers around which the dielectric belt is stretched, the contact state with the dielectric belt is stabilized. It is possible to make the charge amount of the recording medium uniform.

Further, as the above-mentioned control electrode, when a plurality of gates are formed along the conveyance direction of the recording medium, it takes time to currency the image forming area where the recording medium faces the gate. As described above, since the recording medium is uniformly charged and conveyed while being electrostatically adsorbed on the dielectric belt, image forming failure due to floating does not occur. In particular, when a plurality of gates are formed in the transport direction, it is possible to prevent defective image formation due to floating in forming a color image, for example.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to FIGS. In the following description, an image forming apparatus having a configuration corresponding to negatively charged toner will be described. However, when positively charged toner is used, the polarity of each applied voltage can be appropriately set in accordance with that. Good.

FIG. 1 is a schematic sectional view showing the overall construction of the image forming apparatus according to the present invention. In the figure, the image forming apparatus of the present invention includes an image forming unit 1 including a toner supply unit 2 and a printing unit 3. The image forming section 1 visualizes an image on recording paper, which is a recording medium, using toner as visualized particles in accordance with an image signal.
In other words, the image forming apparatus selectively causes the toner to fly and adheres to the recording paper 5 and controls the flying of the toner based on the image forming signal to thereby control the recording paper 5.
A visible image is directly formed on the surface by toner.

A paper feeding device 10 is provided on the paper input side of the recording paper 5 into the image forming section 1. The paper feeding device 10
A paper cassette 4 for storing recording paper 5 as a recording medium,
The paper cassette 4 includes a pickup roller (paper feed roller) 6 for feeding the recording paper 5 one by one, and a paper feed guide 7 for guiding the fed recording paper 5. Further, the paper feeding device 10 has a detection sensor (not shown) for detecting that the recording paper 5 has been fed, provided in the paper feeding path. The pickup roller 6 is rotationally driven by a driving device (not shown).

The toner image formed on the recording paper 5 by the image forming unit 1 is fixed to the recording paper 5 by heating and pressing on the side of the recording paper 5 from the image forming unit 1. The fixing device 11 is provided. Fixing device 11
Is composed of a heating roller 12, a heater 13, a pressure roller 14, a temperature sensor 15, and a temperature control circuit 16. The heating roller 12 is formed, for example, in a state in which a surface of an aluminum tube having a thickness of 2 mm is coated with a fluororesin or the like having good releasability for toner. The heater 13 is, for example, a halogen lamp, and is built in the heating roller 12.

The pressure roller 14 is formed by coating the surface of a tube of aluminum or the like with a member made of silicone resin. The heating roller 12 and the pressure roller 14 provided opposite to each other are pressed at both ends of each shaft with a spring or the like (not shown), for example, 2 kg so that the recording 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 16 is controlled by a main control unit (described later), and controls ON / OFF of the heater 13 based on a measurement result of the temperature sensor 15, and the like.
The temperature of the surface of the heating port 12 is maintained at, for example, 150 ° C.

Further, the fixing device 11 is provided with a paper discharge sensor (not shown) for detecting that the recording paper 5 has been discharged. The heating roller 12, the heater 13, the pressing roller 1
The material such as 4 is not particularly limited. Moreover, the temperature of the surface of the heating roller 12 is not particularly limited. Further, the fixing device 11 may be configured not only to heat-fix the recording paper 5 but also to fix the toner image by pressure-fixing.

Further, although not shown, on the side of the paper output from the fixing device 11, a paper discharge roller for discharging the recording paper 5 processed by the fixing device 11 onto a paper discharge tray, and the discharged recording paper. A paper discharge tray for receiving 5 is provided. The heating roller 12, the pressure roller 14, and the paper discharge roller are driven to rotate by a driving device (not shown), and discharge the recording paper 5.

Toner supply section 2 constituting the image forming section 1
A toner container 20 containing a toner 21 as visualized particles, a toner carrier 22 as a cylindrical carrier (sleeve) for carrying the toner 21 by magnetic force,
And a doctor blade 23 provided inside the toner storage tank 20 to charge the toner 21 and regulate the thickness of the toner layer carried on the outer peripheral surface of the toner carrier 22.

The doctor blade 23 is used for the toner carrier 2
On the upstream side in the rotational direction of No. 2, the distance from the outer peripheral surface of the toner carrier 22 is arranged at an interval of, for example, about 60 μm. The toner 21 has, for example, an average particle size of 6 μm.
The magnetic toner of No. 2 is charged by the doctor blade 23 so that the charge amount is −4 μC / g to −5 μC / g. The distance between the doctor blade 23 and the toner carrier 22 is not particularly limited, and is set appropriately according to the toner conveyance amount. In addition, the average particle size, charge amount, and the like of the toner 21 are not particularly limited, and may be set as needed. Toner carrier 22
Is driven by a driving device (not shown), and arrow A in the figure
Direction, for example, the velocity at the surface is, for example, 100 mm / s
It is rotationally driven at about ec.

The toner carrier 22 is grounded, and magnets are arranged in a fixed state (not shown) at a position facing the doctor blade 23 inside the toner carrier 22 and a position facing a control electrode 26 (described later). ing. Thus, the toner carrier 22 can carry the toner 21 on its outer peripheral surface, and is magnetically attracted (carried) by rotating the toner carrier 22 which is a sleeve. Conveying toner. Further, the toner 21 carried on the outer peripheral surface of the toner carrier 22 forms so-called toner ears at a position corresponding to the magnetic pole position of the fixed magnet on the outer peripheral surface. The rotation speed of the toner carrier 22 is not particularly limited, and may be determined based on the amount of toner to be conveyed. Further, the toner carrier 22 is
Instead of carrying toner 21 by magnetic force, electric force,
Alternatively, it may be configured to carry the electric power and the magnetic force.

The printing unit 3 of the image forming unit 1 has, for example, a thickness of 1
mm carrier made of aluminum plate
The counter electrode 25 facing the outer peripheral surface of
Power supply 30 which is a power supply means of the present invention for supplying high voltage to
A control electrode 26 provided between the toner carrier 22 and the toner carrier 22, a neutralization brush 32, a neutralization power source 17 for applying a neutralization potential to the neutralization brush 32, a charge supply roller 33 for charging the recording paper 5, and the charge A charging power source 18 that applies a charging potential to the supply roller 33, and a motor 34 that is a drive unit for rotating the charge supply roller 33 at a predetermined speed.
1, a dielectric belt 24, support rollers 24a and 24b for supporting and running the dielectric belt 24, and a cleaner blade 19.

The counter electrode 25 is the toner carrier 22.
Is provided so that the distance from the outer peripheral surface of the first member is, for example, 1 mm.

The dielectric belt 24, which runs so as to be in close contact with the counter electrode 25 and electrostatically attracts and conveys the recording paper 5, is formed of polyvinylidene fluoride (PVDF) as a base material. , Its volume resistivity is 10 ¹⁴ Ω
An endless belt having a thickness of about 75 μm in cm. The dielectric belt 24 is a support roller 24.
It is stretched between a and 24b, and is driven by a driving device (not shown), for example, via a support roller 24b, and is rotated in the direction of the arrow in the drawing, for example, at a surface speed of 30 mm / sec.

Further, a high voltage of, for example, 2.3 kV is supplied to the counter electrode 25 by a high voltage power source (control means) 30. In other words, the high voltage supplied from the high-voltage power supply unit 30 causes the toner 2 carried on the toner carrier 22 between the counter electrode 25 and the toner carrier 22.
An electric field required to cause the electron beam 1 to fly in the direction of the counter electrode 25 is applied.

The charging supply roller 33 is made of foamed rubber having urethane as a base material, and has a hardness especially JIS-A30.
And has a resistance value of 10 ⁸ Ω · cm, and is rotationally driven at the same speed as the conveyance speed of the recording paper 5. That is,
The above-described motor 3 is moved at a speed that matches the speed at which the recording paper 5 that is electrostatically adsorbed on the dielectric belt 24 is conveyed.
At 4, the charging supply roller 33 is rotationally driven.
This motor 34 not only drives the charging supply roller 33 to rotate, but also runs the dielectric belt 24.
It may be the same as the drive source that rotationally drives the support roller 24a.

The static elimination brush 32 is the dielectric belt 24.
Further, at a further downstream side of the position facing the control electrode 26 in the rotation direction of, a pressure contact is provided to the dielectric belt 24. The static elimination power source 17 applies a static elimination potential of 2.5 kV to the static elimination brush 32, and eliminates unnecessary charges existing on the surface of the dielectric belt 24.

When the toner 21 adheres to the surface of the dielectric belt 24 due to an unforeseen situation such as paper jam (paper jam), the cleaning blade 19 removes the toner 21 to remove the rear surface of the paper. Is the toner 2
1 to prevent contamination. The counter electrode 2
The material of No. 5 is not particularly limited, and a necessary material may be appropriately set. Also, the distance between the counter electrode 25 and the toner carrier 22 is not particularly limited, and may be set as appropriate. Further, the rotation speed of the counter electrode 25 and the applied voltage are not particularly limited, and may be set appropriately according to the toner used and the speed.

Although not shown, this image forming apparatus
As a control circuit, a main control unit that controls the entire image forming apparatus, an image processing unit that converts surface image data obtained from an image reading device that reads an image of a document or the like into a format of image data to be printed, And an image forming control unit for converting the image data obtained from the image processing section into image data to be applied to the control electrode 26.

Therefore, the control electrode 26 is the counter electrode 25.
It is parallel to the tangential direction of the surface and is two-dimensionally spread opposite to the counter electrode 25, so that the toner flow from the toner carrier 22 to the counter electrode 25 can pass therethrough. Then, the electric field applied between the toner carrier 22 and the counter electrode 25 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 selectively performed. Can be controlled.

The control electrode 26 is disposed 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 detail in FIG. 2, the control electrode 26 includes an insulating substrate 26a, a high-voltage driver (not shown), and independent ring-shaped conductors, that is, ring-shaped electrodes 27.・ It is made up of The substrate 26a is made of, for example, a polyimide resin and has a thickness of 25 μm.

The substrate 26a also has a gate 2 which will be described later.
The holes that should be 9 ... The ring-shaped electrodes 27 ... Are made of, for example, a copper foil, are provided on the surface of the substrate 26a on the toner carrier 22 side, that is, around the holes 29, and are arranged according to a predetermined arrangement.
Each ring-shaped electrode 27 has, for example, a diameter of 220 μm and a thickness of 3
It is formed at 0 μm. Further, the openings 29 ... Of the ring-shaped electrodes 27 are formed to have a diameter of 200 μm, for example, and serve as passage portions 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. The distance between the control electrode 26 and the toner carrier 22 is not particularly limited.

The size of the gates 29 ... And the substrate 2
6a and the ring-shaped electrode 27 ...
There is no particular limitation. Gate 29 above ...
.. That is, for example, 2560 ring-shaped electrodes 27 are formed, and each ring-shaped electrode 27 is individually controlled by a control power supply unit 31 (described later) via a power supply line 28 and a high-voltage driver (not shown). ) Is electrically connected to. The above number is the resolution of 300 DPI in the width of A4 size paper.
It corresponds to (dot per inch) and forms an image for one line.

The number of the ring-shaped electrodes 27 ... Is not particularly limited and is determined by the number of pixels (dots) for forming one line. The gates 29 are not all formed on the same line as shown in the figure, but are divided into four groups in the figure, and the gate groups 29a, 29b, 29c and 29d of each group are formed on the recording paper 5 Conveying direction, especially toner carrier 22
Are sequentially displaced in the moving direction and in the line direction. That is, in the above example, the number of gates 29 is formed in order to form 2560 pixels in one line, and the number of gates in one group is 440. It is formed as shown.

With such a configuration, it is possible to easily shorten the dot interval, and in particular, to overlap the dot intervals so as to eliminate the gap between the circular dots when forming a black solid image. You can Further, it is possible to increase the resolution, and at the same time, by making the distance between the adjacent gates, the ring-shaped electrodes 27, ..., The wirings thereof, etc. can be easily combined, which greatly increases the manufacturing cost of the control electrode. There is an advantage that it can be reduced.

The surface of the ring-shaped electrode 27 ... And the surface of the power supply line 28 are covered with an insulating layer (not shown) having a thickness of about 30 .mu.m. .Insulation between each other, power supply line 28 ... Insulation between each other, and ring-shaped electrodes 2 that are not connected to each other
The insulation between 7 ... and the power supply line 28 ... is secured. The material and thickness of the insulator layer are not particularly limited.

The ring-shaped electrode 27 of the control electrode 26 ...
A pulse corresponding to an image signal, that is, a voltage, is applied to the power supply unit by the control power supply unit (control means) 31. That is, the control power supply unit 31 applies a voltage of, for example, 150 V to the ring-shaped electrodes 27... When the toner 21 carried on the toner carrier 22 passes in the direction of the counter electrode 25.
When not passing, a voltage of, for example, -200 V is applied. As described above, when the voltage (potential) applied to the control electrode 26 is controlled according to the image signal, and the recording paper 5 is sent onto the counter electrode 25 on the side of the counter electrode 25 facing the toner carrier 22, A toner image corresponding to the image signal is formed on the surface of the recording paper 5. The control power supply 31 is controlled by a control electrode control signal sent from an image forming control unit (not shown).

Next, the image forming operation of the image forming apparatus will be described with reference to 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 (step n1), the image data is processed by the image processing unit (step n2), and stored in the image memory (step n3). The image data stored in the image memory is transferred to the image forming control unit (step n4), and the image forming control unit converts the input image data into a control electrode control signal to be given to the control electrode 26. Start (step n5).

When the image forming control unit receives a control signal to be supplied to the control electrodes in a predetermined amount, the toner carrier 22 is rotationally driven (step n7). The rotation of the toner carrier (sleeve) 22 stabilizes the charge amount of the toner carried. After this, the support roller 24a
Is supplied with a high voltage having the same potential as the counter electrode 25 by the high voltage power supply 30 (step n9). Charge supply roller 33
At a charging potential of 1.2 kV by the charging power source 18.
However, a discharging potential is applied to the discharging brush 32 by the discharging power source 17 (step n9).

Here, if it is not the desired control electrode signal, this flow is interrupted in step n6, and an error display (step n20) is performed. Further, if it is confirmed that the control signal is a desired control electrode signal, as described above, when the control signal to be supplied to the predetermined amount of control electrode is obtained, as described above, the counter electrode 25, the charging brush 33, and the discharging brush 3
In the present invention, before the predetermined high voltage is supplied to the ring 2, the potential at which the toner does not fly to all the ring-shaped electrodes 27 of the control electrode 26 is set so as not to fly the toner 21 of the toner carrier 22. Is applied (step n8).

Thereafter, a driving device (not shown) is operated, and the recording paper 5 in the paper cassette 4 is fed out toward the image forming section 1 by the pickup roller 6 which is driven to rotate by the driving device (step n10). At this time, it is confirmed in step n11 whether or not the sheet is in a normal sheet feeding state. That is, when the fed recording paper 5 is detected by the paper feed sensor in the transport path, it is determined that the operation is normal, and the process proceeds to step n12.

The recording paper 5 delivered by the pickup roller 6 is conveyed between the charge supply roller 33 and the support roller 24a. The recording paper 5 is the charge supply roller 3
3 is supplied with an electric charge due to the potential difference between the supporting roller 24a and the supporting roller 24a, and is opposed to the toner carrier 22 of the dielectric belt 24 in the printing unit 3 of the image forming unit 1 as the dielectric belt 24 runs while being electrostatically adsorbed. It is transported to the surface side. Note that the predetermined amount of the control electrode control signal varies depending on the image forming apparatus and the like.

Then, the image forming control unit sends the control electrode control signal to the control power source 31 in step n12.
To supply. The control power supply control signal is supplied at a timing synchronized with the supply timing of the recording paper 5 to the printing unit 3 by the charge supply roller 33. Control power supply unit 3
1 is a control electrode 26 based on the control electrode control signal.
The voltage applied to each ring-shaped electrode 27 is controlled. That is, a voltage of 150 V or -200 V is applied to the predetermined ring-shaped electrode 27 according to the image signal from the control power supply unit 31, and the electric field near the control electrode 26 is controlled. That is, at the gate 29 of the control electrode 26, the toner 2 from the toner carrier 22 to the counter electrode 25 is transferred in accordance with the image data.
Blocking of the flight 1 and its release are appropriately performed. As a result, a toner image corresponding to the image signal is formed on the recording paper 5 moving at a speed of 30 mm / sec toward the paper output side by the travel of the dielectric belt 24.

The recording paper 5 on which the toner image is formed is peeled off from the dielectric belt 24 due to the curvature of the supporting member 24b and conveyed to the fixing device 11, and then the toner image is recorded on the recording paper 5 by the fixing device 11. Is fixed in. The recording paper 5 on which the toner image has been fixed is discharged onto a paper discharge tray by a paper discharge roller, and a normal paper discharge is detected by a paper discharge sensor.

On the basis of this detection operation, the main control section determines the normal end of the printing operation. By the above image forming operation, a good image is formed on the recording paper 5. Since the image forming apparatus directly forms an image on the recording paper 5, the image forming body such as the photoconductor and the dielectric drum used in the conventional image forming apparatus is unnecessary.

Therefore, since the transfer operation for transferring the image from the visualized object to the recording paper is omitted, the image is not deteriorated.
For this reason, the reliability of the device is improved. Further, since the structure of the apparatus is simplified and the number of parts is reduced, it is possible to reduce the size and cost.

Here, the toner carrier 22 and the counter electrode 25
Voltage supply between the charge supply roller 33 and the recording paper 5
Let us consider the electrostatic adsorption transfer of.

As described above, the toner carrier 22 is grounded, while the support roller 24a, which stretches the counter electrode 25 and the dielectric belt 24, has, for example, 2.3 kV, and the charge supply roller 33 has, For example, a high voltage of 1.2 kV is supplied. Therefore, due to the potential difference between the charging supply roller 33 and the support roller 24 a, a negative (minus) charge is supplied to the surface of the recording paper 5 conveyed between the charge supply roller 33 and the dielectric belt 24. Be charged. When this negative electric charge is supplied, the recording paper 5 is electrostatically attracted to the dielectric belt 24 by the electric charge of the electric charge, and the dielectric belt 24 moves so that the recording paper 5 is directly below the gate 29 of the control electrode 26. It is conveyed to the image forming area.

The electric charge on the surface of the dielectric belt 24 is attenuated by the time it reaches just below the gate 29, and the counter electrode 2
The surface potential is about 2 kV due to the balance with the potential of 5. In this state, in order to pass the toner 21 carried on the toner carrier 22 in the direction of the counter electrode 25, the control power supply unit 31 causes the ring-shaped electrode 27.
.. 150 V voltage for each pixel is 150 μs
When ec is applied and the toner 21 does not pass through the gate 29, a voltage of -200V is applied.

In this way, the recording paper 5 is conveyed while being attracted to the dielectric belt 24, and an image of dots is formed by toner on the surface of the recording paper 5 directly below the gate 29 which is an image forming area. .

Therefore, the charge supply roller 33 is rotationally driven by the drive motor 34 at the same speed as the conveyance speed of the recording paper 5. As a result, even if thick paper or an envelope is conveyed as the recording paper 5, the dielectric belt 24 is driven by the driving of the support roller 24b at the same time as the charge supply roller 33 is driven as described above. It is reliably conveyed by the dielectric belt 24 without causing the occurrence. Therefore, the problem caused by the slip of the recording paper 5 is eliminated. In particular, slippage of the image forming front end of the recording paper 5 due to slippage, dirt on the back surface of the recording paper 5, and further the recording paper 5
It is possible to eliminate defective image formation due to uneven charging.

Further, since the charge supply roller 33 is rotationally driven at the same speed as the conveyance speed of the recording paper 5, the charge supply roller 33 can serve as a registration roller, and a separate registration roller needs to be provided. Disappears. That is, the charge supply roller 33 that charges the recording paper 5
By also using as a registration roller, not only the size of the apparatus can be reduced, but also the cost can be reduced. In particular, the charge supply roller 33 can be drive-controlled so that the recording paper 5 fed by the pickup roller 6 is temporarily stopped from being fed by the dielectric belt 24, and the conveyance is started in synchronization with the image formation timing.

For that purpose, the charging supply roller 3 described above is also used.
The motor 34, which is the drive source of No. 3, is effective if it is also used as a drive motor of the support roller 24b that drives the dielectric belt 24. Since it can be driven simultaneously, when the charge supply roller 33 is used as a registration roller. It is effective.

Further, the charge supply roller 33 is arranged so as to face the support roller 24a on which the dielectric belt 24 is stretched and to be pressed against it, as shown in the figure. Therefore, the recording paper 5 can be reliably pressed against the dielectric belt 24, and at the same time, it is useful for stabilizing the charge amount of the recording paper 5. That is, since the pressed state can be kept constant, stable charging can be performed.

In the above description, the toner 21
The ring-shaped electrode 27 of the control electrode 26 to pass through
Although the case where the electric potential applied to (1) is 150 V has been described as an example, the electric potential is not particularly limited as long as the desired flight control of the toner 21 can be performed. Similarly, toner 2
A potential of -200 V is applied to the ring-shaped electrodes 27 ... To prevent 1 from passing therethrough, but this potential may be set appropriately. Further, the supply voltage of the counter electrode 25, the voltage supplied to the charge supply roller 33, and the surface potential of the recording paper 5 immediately below the gate 29 can also be set appropriately if the desired flight control of the toner 21 can be performed. That's good.

Further, by changing the potential applied to the ring-shaped electrode 27 of the control electrode 26, the degree of swelling of the equipotential surface near the gate 29 of the control electrode 26, that is, the state of curving toward the toner carrier 22 side can be controlled. Can be changed. Therefore, the toner 2 passing through the gate 29
1 can be changed.
Accordingly, the dot diameter (FL) of the image formed on the recording paper 5 can be arbitrarily adjusted by appropriately changing the potential applied by the control power supply unit 3l. In this manner, when the toner flying voltage is applied to the control electrode 26 in the state where the high voltage is supplied to the counter electrode 25, the toner is made to fly, and at the same time when the gate 29 passes through, one pixel is scanned as described above. The dot diameter to be formed can be controlled.

According to the control electrode 26 of the structure shown in FIG. 2 of the present invention, the recording paper 5 is formed in order to form one line.
Takes a long time to pass through each gate 29 of the control electrode 26. That is, since the gates 29 are divided into four groups along the conveyance direction of the recording paper 5, even with such a structure of the control electrode 26, the recording paper 5 is not covered with the dielectric belt as described above. Since the toner can be reliably conveyed without being slipped while being electrostatically adsorbed on the toner 24, it is possible to solve the problem when the toner 21 flies and an image is formed. In particular, the recording paper 5 is the charge supply roller 33 as described above.
By the rotation of, the stable charge amount is imparted and the toner is reliably conveyed, so that the toner 21 can be reliably reached on the recording paper 5 without causing an obstacle when flying, and the image quality is not deteriorated.

Since the recording paper 5 is given a uniform charge amount by the charge supply roller 33 described above, the recording paper 5 is electrostatically attracted to the dielectric belt 24 and is not lifted up. Therefore, there is no discharge of electric charges in the area due to partial separation, and therefore, when an image is formed, the electric field between the toner carrier 22 and the toner carrier 22 is stabilized, so that the toner flying control can be reliably performed. Moreover, the charge supply roller 33
Since it is not necessary to increase the potential difference between the support roller 24a and the support roller 24a and increase the amount of charge applied to the recording paper 5, the discharge that occurs at the time of peeling after image formation is eliminated, and the unfixed image may be disturbed. Disappear.

In the above description of the embodiment of the present invention, a single drive as shown in FIG. 2 is used as the control electrode 26, that is, a control electrode of a system of applying a potential to each ring-shaped electrode 27 in accordance with an image signal is used. However, the shape of the control electrode can be similarly implemented by a configuration using a matrix drive as shown in FIG. The matrix drive does not require the required number of drives as many as the number of gates, so that there is an effect that the number of gates can be significantly reduced and cost can be reduced.

As shown in FIG. 4, the control electrode 26 is connected to the substrate 2
Strip-shaped electrode groups 27a and 27b are formed on the front surface and the back surface of 6a in a state of intersecting (intersecting) each other. Gates 29 for passing the toner flow are formed at respective positions where the strip-shaped electrode groups 27a and 27b intersect on the front and back surfaces.

Then, a toner flying potential according to an image signal, for example, is applied to the strip electrode group 27a on the surface. Further, a toner flying potential according to a scanning signal that is periodically switched is applied to the strip-shaped electrode group 27b on the back surface. As a result, in a state where the toner flying potential is simultaneously applied to the strip-shaped electrode groups 27a and 27b on the front and back surfaces where the gate 29 intersects,
The toner 21 of the toner carrier 22 is ejected and the gate 29
After passing through, the particles will be flown to the counter electrode 25.

The control electrode 26 having such a configuration is similar to the control electrode 26 shown in FIG. 2 and does not hinder the conveyance of the recording paper 5 or the like. Particularly, when the recording paper 5 is evenly charged, the dielectric belt 24 runs,
Since the toner is transported to the image forming area, it is possible to solve the problem that the toner flying control cannot be accurately performed due to the imbalance of the potential for the toner flying control, and the image forming failure occurs even if the time for passing through the image forming area is long. Accurate image formation can be performed without occurrence.

Further, in the embodiments of the present invention, the case where the monochromatic toner is used as the image-developing particles has been described. This is for forming an image in at least a single color, and it is necessary to use toners of a plurality of colors when forming a color image. Therefore, the toner carrier 22 shown in FIG. 1 is provided in the number corresponding to each color, and the toner carrier 22 is provided side by side along the conveyance direction of the recording paper. For example, as the visualized particles, yellow, magenta,
When cyan and black toners are used, the control electrodes (26a, 26b, 26c, 26d) corresponding to the respective toner carriers (22a, 22b, 22c, 22d),
Opposing electrodes (25a, 25b, 25c, 25d) are provided along the conveying direction of the recording paper 5, respectively.

Even in such an apparatus for forming a color image, the recording paper 5 is electrostatically and reliably attracted onto the dielectric belt 24 by the action of the charge supply roller 33, and the recording paper 5 reaches the image forming area of each color. The dielectric belt 24 is conveyed as it travels. At this time, the recording paper 5 is reliably conveyed without rising or the like, and images of toner of each color are sequentially formed. Therefore, even if the recording paper 5 passes through the image forming area for a long time, the recording paper 5 can be stably conveyed, and at the same time, the image can be formed in a normal state.

The case where the visualized particles are toners has been described, but the visualized particles may be ink or the like. In addition, the configuration of the toner supply unit 2
It is also possible to adopt a configuration to which the ion flow method is applied. That is, the image forming unit 1 may be configured to include an ion source such as a corona charger. Even in this case, the same effects as the above can be obtained.

The image forming apparatus according to the present invention is, for example,
The printing unit of digital copiers and facsimile machines,
It can be suitably applied to digital printers, plotters and the like.

[0094]

According to the image forming apparatus of the present invention described above, the recording medium is electrostatically adsorbed on the dielectric belt and conveyed to the image forming area where the developing particles fly. Therefore, it is possible to solve the problem caused by the slip of the recording medium.

In particular, as a means for electrostatically charging the recording medium, by providing a roller driven at the same speed as the recording paper conveying speed, not only can the charge amount on the recording medium be stabilized. Since the roller can also be used as a registration roller, it can contribute to downsizing of the apparatus and cost reduction.

Further, since the recording medium is securely attracted electrostatically onto the dielectric belt and conveyed to the image forming area, the state can be maintained even if the image forming area becomes long. There is no problem at the time of image formation, and it is possible to form a good quality image without image deterioration.

Further, even if the recording medium is peeled off from the dielectric belt, an excessive electric charge is not applied to the recording medium, so that the formed image is not disturbed by the discharge at the time of peeling.

As described above, it is possible to carry out image formation in a stable state without causing conveyance failure of the recording medium and image deterioration caused by the conveyance failure.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view illustrating an entire configuration of an image forming apparatus according to the present invention.

FIG. 2 is a plan view illustrating a detailed configuration of a part of a control electrode included in the image forming apparatus according to the present invention.

FIG. 3 is a flowchart showing a flow of recording control operation.

FIG. 4 shows another specific example of the control electrode and is a plan view of the control electrode having a matrix configuration.

FIG. 5 is a sectional view for explaining an image forming principle of a conventional image forming apparatus.

FIG. 6 is a control circuit configuration diagram for controlling application of a voltage for controlling toner flight to a ring-shaped electrode that constitutes a control electrode for controlling toner flight, in accordance with an image signal.

[Explanation of symbols]

 1 Image Forming Section 2 Toner Supply Section 3 Printing Section 5 Recording Paper (Recording Medium) 18 Charging Power Supply (Power Supply Means) 21 Toner (Visualizing Particles) 22 Toner Carrier 24 Dielectric Belts 24a, 24b Support Rollers (Belt Driving Means) ) 25 counter electrode 26 control electrode 27 ring-shaped electrode 29 gate 30 high-voltage power supply section (control means) 31 control power supply section (control means) 33 charge supply roller (roller member) 34 drive motor (roller drive means)

Claims (4)

[Claims] 1. A carrier for supporting the visualized particles, a counter electrode disposed opposite to the carrier, and a passage for the visualized particles disposed between the carrier and the counter electrode. A control electrode having a plurality of gates, a recording medium conveyed on the counter electrode and an image formed by the visualized particles is formed,
By applying a potential that causes a predetermined potential difference between the carrier and the counter electrode, and changing the potential applied to the control electrode, the passage of the visualized particles through the gate is controlled and conveyed. An image forming apparatus comprising: a control unit for forming an image on a recording medium, the endless dielectric belt being fed along the counter electrode, and a plurality of rollers stretching the dielectric belt. A belt driving unit that drives at least one roller, and contacts the dielectric belt via the recording medium before image formation, and conveys the recording medium to an image forming area facing the control electrode. And a roller member that is driven to rotate in a direction that causes the recording medium to have the same polarity as the visualized particles and is electrostatically adsorbed to the dielectric belt to be conveyed so as to have a predetermined size. An image forming apparatus comprising: a power supply unit that applies a potential. 2. The image forming apparatus according to claim 1, wherein the roller member is rotationally driven at the same speed as the conveying speed of the recording medium. 3. The image forming method according to claim 1, wherein the roller member is provided in a pressure contact state at a position facing one downstream support roller around which the dielectric belt is stretched. apparatus. 4. The image forming apparatus according to claim 1, wherein a plurality of gates of the control electrode are formed along a recording medium conveyance direction.