JP3313601B2 - Image forming device - Google Patents

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, an electric field is applied to a toner as a developer as disclosed in Japanese Patent Application Laid-Open No. Hei 5-134581. By causing the toner to fly by electric force and changing the potential applied to a control electrode including a plurality of through-holes arranged on the flight path to directly adhere to the recording medium,
An image forming apparatus that directly forms a toner image on the recording medium has been proposed.

In the above prior art, a developing sleeve as a developer carrier, a counter electrode, and a control electrode having an opening therebetween are arranged. According to the above-mentioned prior art, it is possible to form a toner image directly on the paper surface by controlling the flying of the toner by switching between a potential that causes the toner to pass through the opening of the control electrode and a potential that does not pass through the opening by image data. It has become.

[0004] The above technique has a counter electrode formed of a mesh-shaped roller and a decompression means inside the roller.
The recording medium is conveyed by rotation of the roller in a state where the recording medium is sucked to the roller by using a suction force for sucking air from an opening of the mesh.

[0005]

In an image forming apparatus of the type which directly forms an image by flying toner as represented by the above-mentioned prior art, an image is formed by controlling the potential of a control electrode. In the above image forming apparatus, it is desirable that the distance between the control electrode and the counter electrode is uniform and constant. Further, it is a good image forming condition that the position of the recording medium, that is, the distance between the control electrode and the recording medium is kept constant.

However, since the distance between the control electrode and the counter electrode is very small as described above, when plain paper or the like is used as a recording medium, the recording medium may have wrinkles, curls, elastic forces, etc., and may have a different recording medium. The position of the recording medium and the control electrode or the counter electrode changes depending on the electric force received by the electric charges generated in the recording medium.
When the position of the recording medium changes, the shape and size of the dots to be printed change, and a desired image may not be formed. In addition, the reproducibility of the halftone is reduced due to the change in the shape and size of the formed dot, so that an appropriate halftone cannot be obtained, and it is difficult to form a good image.

When the position of the recording medium changes greatly, it may come into contact with the control electrode. In this case, the toner already flying on the recording medium is rubbed by the contact of the control electrode to cause image destruction.In addition, the toner attached to the control electrode adheres to the recording medium to cause fogging or the toner adhesion. When it is severe, it appears as black streaks or sunspots.

When the recording medium comes into contact with the control electrode, the electric charge of the recording medium is induced on the control electrode surface, and the electric charge on the control electrode surface has a potential with respect to the control electrode.
Therefore, the apparent potential of the control electrode viewed from the toner carried on the toner carrier changes to a potential different from the desired potential applied to the control electrode. Therefore, even if a potential is applied to the toner so that the toner passes through the passage hole, the toner flies insufficiently or becomes difficult to fly itself, resulting in image dropout or poor printing, making image formation difficult. Further, even if an image is formed, the toner does not fly sufficiently, resulting in a blurred image in which contrast cannot be obtained. In addition, it is difficult to reproduce halftone.

When the apparatus is placed in a high-temperature, high-humidity environment, the recording medium to be used absorbs moisture and the resistance is reduced. The high voltage leaks to the control electrode, causing damage to the control electrode and control circuit, and other devices and other connected equipment, and in the worst case, causing electric shock to the user.

When an image forming apparatus as disclosed in Japanese Patent Application Laid-Open No. 5-134581 is used and a recording medium having a small width such as a postcard is used, an area where the recording medium does not exist during a printing operation occurs. Further, since the recording medium must be attracted to the counter electrode and the counter electrode must be rotated and conveyed, it is necessary to suction the recording medium with a strong force. In this way, a certain amount or more of airflow is formed in the region facing the control electrode. By the way, at the end of the region where the recording medium does not exist, the toner exists on the opening of the control electrode facing the region and on the developing sleeve facing the opening. When an airflow is directly formed on the toner, not only is the toner layer disturbed, but also the toner adhering to the opening and the toner existing on the developing sleeve in a region facing the opening are caused by the airflow. There is a case where the flying is started with the initial velocity being given, and the flying is made toward the counter electrode to contaminate the counter electrode. Further, it may fly on an adjacent recording medium to cause fogging or image deterioration. This may cause unnecessary toner consumption.

Further, in the case of a color image forming apparatus using a plurality of developing tanks as in the prior art, the developing and cleaning operations may be performed simultaneously. For example, consider a case where development is performed by a developing tank of one color and a recording medium does not exist on the surface of the counter electrode facing the developing tank of another color. In this case, when the control electrode facing the counter electrode is cleaned, the color toner of the color being cleaned may float by a cleaning operation, for example, brush cleaning. For this reason, there is a possibility that the above-mentioned floating toner may fly on the recording medium existing on the surface of the counter electrode during printing and induce partial color fogging or color mixing.

An object of the present invention is to provide an image forming apparatus capable of improving the quality of image formation by keeping the distance between the recording medium and the control electrode constant and preventing unnecessary developer flying and floating. is there.

[0013]

According to the present invention, there is provided a carrier for supporting a developing agent, a counter electrode arranged opposite to the carrier, and a developing device arranged between the carrier and the counter electrode. A control electrode composed of electrodes provided around a plurality of gates serving as a passage portion of the agent; a transport unit for transporting a recording medium for recording an image between the control electrode and the counter electrode; A potential that causes a predetermined potential difference between the body and the counter electrode is applied, and the passage of the developer through the gate is controlled by changing the potential applied to the control electrode. A control unit for forming an image on the recording medium conveyed between the opposing electrodes. And image forming according to the first invention.
Apparatus includes a chamber <br/> chromatography in which a suction port in the vicinity of the opposite electrode, and a pressure reducing means for reducing the pressure on the Symbol chamber,
The air pressure above Symbol chamber by the pressure reducing means
Exhaust and by vacuum sucking said recording medium to said suction port, the upper
At a predetermined position between the control electrode and the counter electrode,
A suction means for sucking and holding the recording medium;
As the gap between them goes downstream in the conveyance of the recording medium,
And the recording medium is
Arrange so that the front end on the downstream side of the conveyance reaches the area to be sucked into the mouth.
And a guide member provided .

An image forming apparatus according to a second aspect of the present invention has an exhaust port
And an intake port provided near the counter electrode.
Number of chambers and the
A pressure reducing means for reducing the pressure in the chamber,
-Reduce the internal pressure from the exhaust port by the
And depressurized and sucked the recording medium into the air inlet
And at a predetermined position between the control electrode and the counter electrode.
An adsorbing means for adsorbing and holding the recording medium;
The exhaust ports of the chamber are formed adjacent to each other.
The decompression means is provided in the vicinity of the adjacent exhaust port.
To reduce the pressure inside each adjacent chamber
It is characterized by having .

According to a third aspect of the present invention, there is provided an image forming apparatus comprising:
Multiple chambers with inlets near the counter electrode,
A pressure reducing means for reducing the pressure in the chamber.
The air in the chamber is exhausted by the above-mentioned pressure reducing means.
The pressure is reduced and the recording medium is sucked into the suction port, and the control
Place the recording medium at a predetermined position between the pole and the counter electrode.
An adsorption means for adsorbing and holding, the chamber and the
The pressure reducing means transports the recording medium with respect to the counter electrode.
It is necessary to be provided upstream and downstream in the
And features .

According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising:
Multiple chambers with inlets near the counter electrode,
A pressure reducing means for reducing the pressure in the chamber.
The air in the chamber is exhausted by the above-mentioned pressure reducing means.
The pressure is reduced and the recording medium is sucked into the suction port, and the control
Place the recording medium at a predetermined position between the pole and the counter electrode.
An adsorption means for adsorbing and holding, the chamber and the
The pressure reducing means is in a direction perpendicular to the conveying direction of the recording medium.
Characterized by being arranged in

According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising:
The attachment means includes a plurality of suction ports provided near the counter electrode.
A chamber, and a decompression means for depressurizing the inside of the chamber.
And the pressure in the chamber is reduced by the pressure reducing means.
To exhaust the air and reduce the pressure, and suck the recording medium into the intake port.
A predetermined position between the control electrode and the counter electrode.
A suction means for sucking and holding the recording medium;
The chamber is the recording medium on which the chamber boundary is conveyed.
Within the width of the recording medium and at positions near both ends of the recording medium.
It is characterized by being arranged so that .

An image forming apparatus according to a sixth aspect of the present invention comprises:
In the third, fourth or fifth image forming apparatus, the pressure reduction
The means can be operated other than at the time of transporting the recording medium,
Exhaust the air sucked from the intake port to the outside of the device.
Features .

According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising:
In the image forming apparatus according to the present invention, the opening of the intake port
The size of the portion is variable .

An image forming apparatus according to an eighth aspect of the present invention has a sixth aspect.
In the image forming apparatus according to the present invention, the inside of the chamber
External exhaust for exhausting the air outside the device by the above-mentioned pressure reducing means.
The air passage and the exhaust opening of the external exhaust passage are not blocked.
And a discharge tray for covering the
The formed recording medium is discharged .

An image forming apparatus according to a ninth aspect is characterized in that
A chamber provided with an air inlet near the counter electrode;
A pressure reducing means for reducing the pressure in the chamber,
The internal pressure is reduced by evacuating the air by the pressure reducing means.
The recording medium is sucked into the suction port, and the control medium is
The recording medium is held at a predetermined position between the
Holding means for holding, the counter electrode and the suction means
At least part of which is formed into a detachable single unit
It is characterized by having .

An image forming apparatus according to a tenth aspect of the present invention is configured such that
A chamber provided with an air inlet near the counter electrode;
A pressure reducing means for reducing the pressure in the chamber,
-The pressure in the interior is reduced by exhausting air by the
Then, the recording medium is sucked into the air inlet, and the control electrode and
Absorbs the recording medium at a predetermined position between the opposing electrodes
Holding means for holding, the carrier and the counter electrode,
Are arranged one by one for each of a plurality of color developing agents and printed.
A pair of the above-mentioned carrier and the above-mentioned counter electrode which are not operated
In the area of the above, intake was enabled by the decompression means
It is characterized by the following .

An image forming apparatus according to an eleventh aspect of the present invention has a first
An image forming apparatus according to any one of claims 10 to 10,
The transporting means includes a pair of the counter electrode and the control electrode.
Located upstream in the transport direction of the recording medium with respect to the orientation area
And the recording medium between the control electrode and the counter electrode.
Supply and conveyance means for supplying the control electrode,
The downstream side in the transport direction of the recording medium with respect to the area facing the poles
Disposed between the control electrode and the counter electrode from above
A discharge conveying means for discharging the recording medium;
A stage is disposed between the supply and discharge means and the discharge and transfer means.
And the supply / conveyance means and the discharge / conveyance means
The interval is smaller than the length of the recording medium in the transport direction.
It is characterized by being arranged as follows.

An image forming apparatus according to a twelfth aspect has a first
An image forming apparatus according to any one of the first to eleventh aspects,
And at least an air inlet in the conveying direction of the recording medium.
Forming part is inclined in the intake direction so as to narrow the intake port
The image forming apparatus according to claim 1, wherein:

An image forming apparatus according to a thirteenth aspect has a first
An image forming apparatus according to any one of the first to twelfth aspects.
The suction means provides an opening in the chamber,
The opening accommodates at least a part of the counter electrode, and
Features that the opening other than the accommodation part of the
And

In the present invention, unlike the prior art, the opposing electrode is not used as one of the conveying means by suction of the recording medium.
A recording medium is conveyed by providing a suction means. Therefore, even if the strength of the suction is limited, the recording medium is kept at a predetermined level so that the air flow toward the suction port of the suction means in which the recording medium is not present has a strength that does not cause the developer of the carrier or the control electrode to fly. And can be transported. In addition, a counter electrode having an ideal plane instead of a curved surface for image formation can be used, and good image formation is also possible.

In the present invention, at least the recording medium
Narrow the air inlet at the part where the air inlet is formed in the body transport direction
Thus, even if the leading end of the recording medium is about to enter the intake port when the recording medium is conveyed, the leading end of the recording medium abuts the formed slope, and the original slope follows the slope. To the transfer position.

In the present invention, since the counter electrode is housed in the chamber, a part of the intake port is constituted by the counter electrode. That is, the side surface portion of the counter electrode becomes a part of the intake port. Accordingly, the recording medium is attracted at the position closest to the counter electrode, and the recording medium can be favorably held along the image forming surface of the counter electrode.

In the present invention, the guide member is arranged in a region where the recording medium is sucked into the intake port, and guides the recording medium to the intake port. Even if the recording medium has curls or wrinkles, it is sucked by the suction port and does not cause poor suction.

In the present invention, a plurality of chambers share the decompression means. Therefore, as compared with the case where the decompression means is provided for each chamber, the number of decompression means is reduced and the number of parts can be reduced. Further, since there are a plurality of chambers, even if one of the chambers facing the decompression means is in an open state, the decompression of the other chamber is maintained.

In the present invention, since the decompression means and the chamber are arranged upstream and downstream of the counter electrode, the suction force is reduced even when the recording medium exists only in either the upstream or downstream of the counter electrode. Never invite.

In the present invention, since the pressure reducing means is arranged at right angles to the transport direction of the recording medium, when a narrow recording medium is used, for example, even if the suction port of one chamber is open. In addition, the suction power of the other chamber does not decrease.

In the present invention, since the plurality of chambers are arranged according to the size of each recording medium to be conveyed, almost all of the recording medium can be sucked regardless of the size of the recording medium being conveyed. .

In the present invention, it is possible to easily recover the developer floating in the apparatus, particularly in the vicinity of the control electrode or the counter electrode, by utilizing the air flow toward the intake port.
In particular, by operating the pressure reducing means at the time of cleaning the electrode or at the time of abnormal stop such as paper jam, the developer floating in the apparatus can be collected, so that the counter electrode is not contaminated by the developer, and the recording medium is prevented. No back stain occurs. Further, by always operating the decompression means, it is possible to suck high-temperature air using the fixing means and a power supply as a heat source from the intake port, so that the apparatus can be cooled, and it is not necessary to provide a separate cooling means. .

In the present invention, the size of the opening of the intake port is large.
Since the size is variable, for example , if the area of the opening of the intake port is increased during the cleaning operation or the like, the developing agent that floats accordingly can be collected.

In the present invention, an exhaust port for exhausting air from the apparatus and a discharge tray for recording media are arranged on the same surface of the apparatus. The discharge tray can also serve as a shielding member that prevents discharge of the developer from the exhaust port.

In the present invention, since the counter electrode and the suction means are configured as a single unit, each unit can be replaced without maintenance for each component. Therefore, even a general user can easily handle.

In the present invention, during printing, air can be taken in by the pressure reducing means even in the area of the pair of the above-mentioned carrier and the above-mentioned counter electrode where the image forming operation is not performed. For example, it is possible to satisfactorily collect the scattered developer when the cleaning operation is performed on the control electrode at the same time, and it is possible to avoid color mixing and fogging due to the scattered developer during the cleaning. By always operating the pressure reducing means, high-temperature air can be sucked from the suction port by using the fixing means and a power supply as a heat source, and the apparatus can be cooled.

[0039]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram showing an embodiment of a printer which is an image forming apparatus according to the present invention. FIG. 2 is a configuration diagram of a main part mainly of an image forming unit of the printer. 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 each applied voltage may be appropriately set accordingly. Good.

This image forming apparatus includes an image forming section 1 having a toner supply section 2 and a printing section 3. The image forming section 1 visualizes an image corresponding to an image signal on a sheet as a recording medium using toner as a developer. In other words, this image forming apparatus directly forms an image on paper by causing toner to fly and adhere to paper, and controlling the flight of the toner based on an image signal.

On the paper entry side of the image forming unit 1,
A paper supply unit 10 serving as a paper supply / conveyance unit is provided. As shown in FIG. 2, the paper supply unit 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 that guides the supplied paper 5. 7 and a pair of registration rollers 95. Also, the paper supply unit 10 stores the paper 5
Is provided with a paper feed sensor (not shown) for detecting that the paper is supplied. The pickup roller 6 is driven by a driving device (not shown).

On the paper output side of the sheet 5 from the image forming section 1, the toner image formed on the sheet 5 by the image forming section 1 is fixed to the sheet 5 by heating and pressurizing to discharge the sheet. A fixing unit 11 for performing the fixing is provided. The fixing unit 11, which is also a discharge conveyance unit, includes a heating roller 12, a heater 13, a pressure roller 14, a temperature sensor 15, and a temperature control circuit 1.
Consists of six. The heating roller 12 is made of, for example, an aluminum tube having a thickness of 2 mm. The heater 13 is formed 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. And
A load of, for example, 2 kg is applied to both ends of each shaft by a spring or the like (not shown) so that the heating roller 12 and the pressure roller 14 provided opposite to each other can be pressed with the paper 5 therebetween. ing. 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), controls ON / OFF of the heater 13 based on the measurement result of the temperature sensor 15, and sets the temperature of the surface of the heating roller 12 to, for example, 150 ° C. Hold. Further, the fixing unit 11
Is provided with a paper discharge sensor (not shown) for detecting that the paper 5 has been discharged.

Although not shown, a discharge roller for discharging the sheet 5 processed by the fixing unit 11 onto a discharge tray, and a discharged sheet 5 A receiving tray is provided. The heating roller 12, the pressure roller 14, and the paper discharge roller are driven by a driving device (not shown).

The heating roller 12, the heater 13, the pressure roller 14 and the like are not particularly limited to the above-mentioned materials. Further, the surface of the heating roller 12 is not particularly limited to the above-mentioned temperature. Further, the fixing unit 11 controls the paper 5
May be configured to fix the toner image by heating or pressing.

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 serving as a cylindrical carrier (sleeve) for carrying the toner 21 by magnetic force, and provided inside the toner storage tank 20 to charge the toner 21 and to cover the outer peripheral surface of the toner carrier 22 The doctor blade 23 controls the thickness of the carried toner layer. 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. Toner 2
Reference numeral 1 denotes a magnetic toner having an average particle diameter of, for example, 6 μm.
The charge is applied so as to be g to -5 [mu] C / g.
The distance between the doctor blade 23 and the toner carrier 22 is not particularly limited to the above value. Further, the average particle size, the charge amount, and the like of the toner 21 are not particularly limited to the above values.

The toner carrier 22 is driven by a driving device (not shown), and rotates in a direction indicated by an arrow A in FIG. Further, the toner carrier 22 is grounded, and a position inside the toner carrier 22 facing the doctor blade 23 and the control electrode 26.
A magnet (not shown) is arranged at a position facing (described later). Thus, the toner carrier 22 can carry the toner 21 on its outer peripheral surface. Further, instead of supporting the toner 21 by a magnetic force, the toner carrier 22 may be configured to support the toner 21 by an electric force or an electric force and a magnetic force.

The printer, which is an image forming apparatus, includes, as a control circuit, a main control unit for controlling the entire image forming apparatus, and image data to be printed on image data obtained from an image reading apparatus for reading an image of a document or the like. An image processing unit that converts the image data into a format, an image memory that stores the converted image data, and an image forming control unit that converts the image data obtained from the image processing unit into image data to be given to the control electrode 26. Have.

The printing section 3 of the image forming section 1 includes a counter electrode 25 having a flat surface 25a facing in parallel with the outer peripheral surface of the toner carrier 22, a high-voltage power supply 30 for supplying a high voltage to the counter electrode 25, and A control electrode 26 provided between the toner carrier 22 and the cleaning brush 25b is provided. Here, the counter electrode 25 is made of, for example, aluminum.

The flat surface 25a is provided such that the distance from the outer peripheral surface of the toner carrier 22 is, for example, 1.1 mm. The surface of the flat surface 25a has a volume resistivity of 10 ⁸ Ω.
-A fluorine coat layer having a thickness of 75 cm and a thickness of 75 cm is provided. The counter electrode 25 is driven by a driving device (not shown) by a rotation shaft 25d, and can rotate in the direction of arrow B in the figure. When the cleaning brush 25b comes to a position facing the control electrode 26, the cleaning brush 25b can contact the control electrode 26. Further, a high voltage of, for example, 2 kV is applied to the counter electrode 25 by a high voltage power supply means (control means) 30. That is, the counter electrode 25 and the toner carrier 2
An electric field necessary for causing the toner 21 carried on the toner carrier 22 to fly in the direction of the counter electrode 25 is applied by the high voltage applied from the high voltage power supply means 30 to the space between the two.

Further, the cleaning member 3 is brought close to the counter electrode 25.
7 and a support member 38 are provided. The same potential as the potential applied to the counter electrode 25 during printing is always applied to the cleaning member 37 by the high voltage power supply means 30 during operation of the apparatus. The counter electrode 25, the fluorine coating layer on the flat surface 25a,
The material of the cleaning brush 25b does not deviate from the scope of the present invention,
There is no particular limitation as long as good operation is guaranteed. Further, the distance between the counter electrode 25 and the toner carrier 22 and the applied voltage are not particularly limited to the above values.

The control electrode 26 is parallel to the tangential direction of the surface of the counter electrode 25 and is two-dimensionally spread opposite to the counter electrode 25.
The toner flow in five directions can be passed. 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 controlled. You. 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).

FIG. 3 is a configuration diagram of the control electrode. The control electrode 26 includes an insulating substrate 26 a, an independent ring-shaped conductor, that is, a ring-shaped electrode 27,
The power supply line 28 is a wiring connected to the ring-shaped electrode 27, and a high-voltage driver (not shown). The substrate 26a is made of, for example, a polyimide resin and has a thickness of 25 μm. Also, the substrate 2
In 6a, a through-hole to be a gate 29 described later is formed. The ring-shaped electrode 27 is made of, for example, copper foil, is provided on the surface of the substrate 26a on the toner carrier 22 side, that is, around the hole, and is arranged according to a predetermined arrangement. Each ring-shaped electrode 27 has, for example, a diameter of 2
It has a thickness of 20 μm and a thickness of 30 μm. Further, a gate 29 which is a through hole provided in each ring-shaped electrode 27 is provided.
Has a diameter of, for example, 200 μm, and serves as a passage portion for the toner 21 flying from the toner carrier 22 to the counter electrode 25. The control electrode 26 and the toner carrier 22
Is not particularly limited to the above value.
The size of the gate 29 and the thickness of the material of the substrate 26a and the ring-shaped electrode 27 are not particularly limited to the above values.

The gate 29 and the ring-shaped electrode 27 are
For example, each of the ring-shaped electrodes 2
7 is electrically connected to a control power supply unit 31 (described later) via a power supply line 28 and a high-voltage driver (not shown). The above number corresponds to a resolution of 300 DPI (Dot Per Inch) in the width of A4 size paper. Note that the number of ring-shaped electrodes 27 is not particularly limited to the above value.

The surface of the ring-shaped electrode 27 and the surface of the power supply line 28 are covered with a 30 μm-thick insulator layer (not shown).
Thereby, the insulation between the ring-shaped electrodes 27, the insulation between the power supply lines 28, and the insulation between the ring-shaped electrode 27 and the power supply line 28 that are not connected to each other are ensured. ing. The material and thickness of the insulator layer are not particularly limited.

A pulse corresponding to an image signal, that is, a voltage is applied to the 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
Applies, for example, 150 V to the ring-shaped electrode 27 when the toner 21 carried by the toner carrier 22 passes in the direction of the counter electrode 25, and applies -200 V to the ring-shaped electrode 27 when the toner 21 is not allowed to pass. ing. 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 surface of the paper 5 is responsive to the image signal. A toner image is formed. The control power supply 31 is controlled by a control electrode control signal sent from an image forming control unit (not shown).

In addition, the printer has a paper suction section 92 for holding and transporting the paper 5 at a predetermined position so as to contact the flat surface 25a. FIG. 4 is an enlarged configuration diagram illustrating the paper suction unit. The paper suction section 92 includes fans 93a and 93b serving as decompression means, a chamber 96, and the chamber 9.
6, a plurality of air inlets 94 are provided, and air suction is performed so that the paper 5 does not contact the control electrode 26. The image forming apparatus is used as a printing unit of a printer as described above, but can also be used as a printing unit of a fax or a digital copy.

For example, an image forming operation of the image forming apparatus when used as a digital copy printing unit 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 unit and a copy start button (not shown) is operated, the main control unit that has received this input starts an image forming operation. That is, a document image is read by the image reading unit (step S1), the image data is processed by the image processing unit (step S2), and stored in the image memory (step S3).

The image data stored in the image memory is transferred to the image forming control unit (step S4), and the image forming control unit starts to convert the input image data into a control electrode control signal applied to the control electrode 26. (Step S5). Further, upon obtaining a predetermined amount of the control electrode control signal, the image formation control unit determines whether or not this is a desired control electrode signal (step S6). If it is not the desired control electrode signal, an error is displayed (step S7). In the case of a desired control electrode signal, the sleeve is rotated (step S8), and -200 V is applied (step S9).
The toner carrier 22 and the fan 93 are driven (step S
10) At the same time, a driving device (not shown) operates. The sheet 5 in the sheet cassette 4 is sent out toward the image forming section 1 by the pickup roller 6 shown in FIG. 2 driven by the driving device (step S11), and the sheet feeding sensor detects that the sheet is in a normal sheet feeding state. (Step S
12). If the paper feeding state is not normal, an error display is performed (step S13). The sheet 5 picked up by the pickup roller 6 is sent out by the registration roller 95 and is conveyed to the surface of the printing section 3 of the image forming section 1 facing the toner carrier 22 on the flat surface 25 a while being adsorbed by the sheet adsorbing means 92. Is done. The predetermined amount of the control electrode control signal varies depending on the configuration of the image forming apparatus.

After that, 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 3. The control power supply unit 31 controls the high voltage applied to each ring-shaped electrode 27 of the control electrode 26 based on the control electrode control signal (step S).
14). That is, a voltage of 150 V or -200 V is appropriately applied to the predetermined ring-shaped electrode 27 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 prevention of the flying 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 rotation of the registration roller 95 causes
A toner image corresponding to the image signal is formed on the paper 5 moving at a speed of 0 mm / sec.

The paper 5 on which the toner image is formed is fixed to the fixing unit 11.
, The toner image is fixed on the sheet 5 by the fixing unit 11. The paper 5 on which the toner image has been fixed is discharged onto a paper discharge tray by a paper discharge roller, and normal discharge is detected by a paper discharge sensor. Based on this detection operation, the main control unit determines whether the printing operation has ended normally (step S15).

Incidentally, a good image is formed on the sheet 5 by the image forming operation. In the present image forming apparatus, an image is formed directly on the sheet 5, and therefore, a visualized body such as a photoconductor and a dielectric drum used in a conventional image forming apparatus is not required. Therefore, the transfer operation of 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 apparatus is simplified and the number of parts is reduced, the size and the cost can be reduced.

Next, individual controls of the above embodiment will be described. FIG. 6 is a timing chart of signals applied to the counter electrode. As shown in FIG. 6, t indicates a printing interval, that is, a sheet interval (between a printed sheet and the next sheet). The counter electrode drive signal is given in a time T shorter than the time t,
The opposing electrode 25 is controlled so as to make one rotation by the driving means of the opposing electrode 25. During this time, a high voltage is always supplied to the counter electrode 25 (see the counter electrode potential in FIG. 6).

The polarity of the high voltage supplied during this time is switched during time T as shown in FIG. In the present embodiment, the cleaning power source 30b switches the cleaning reverse potential -500V by the switching unit 30c, and the cleaning brush 2
5b. The cleaning potential is the counter electrode 2
At the end of the drive of 5, the high voltage of 2 kV necessary for the printing operation output again by the high voltage power supply 30a is switched by the switching means 30c so as to be applied.

In the above control, during the printing operation, the counter electrode 25
Is always parallel to the control electrode 26 in parallel. Then, during the non-printing operation, particularly between the sheets, the cleaning brush 25b can come into contact with the control electrode 26 in the process of rotating the counter electrode 25 once as shown in FIG. At a position facing the control electrode 26, the cleaning brush 25b is in contact with or very close to the control electrode 26. Even at this moment, since a high voltage is applied to the counter electrode 25, a very high electric field can be applied to the toner 21 attached to the control electrode 26, and the toner 21 attached to the control electrode 26 is cleaned by a cleaning brush. 2
5b allows easy removal. The same potential as in the printing operation is applied to the counter electrode 25 as described above, and the potential is applied to the toner 21 adhering from the tip of the cleaning brush 25b because it is in contact with or close to the control electrode 26. The electric field is much stronger than that of printing. Therefore, the toner that has not been sucked by the counter electrode 25 during the printing operation is sucked by the cleaning brush 25b, and the control electrode 26 can be cleaned. In addition, since the potential of the cleaning brush 25b is switched during cleaning as described above, the oppositely charged toner 21 can be removed.

Next, the cleaning brush 25b is finally separated from the control electrode 26 by the rotation of the counter electrode 25 and is again
5a stops at a position facing the control electrode 26, and printing is performed on the next sheet 5. The cleaning member 37 can contact the cleaning brush 25b and the flat surface 25a when the counter electrode 25 is rotating, and can contact the cleaning brush 25b and the flat surface 25a when the counter electrode 25 is rotating. And the toner adhering to the cleaning brush 25b can be cleaned. The same potential as the potential applied to the counter electrode 25 during the printing operation is applied to the cleaning member 37, so that it is possible to electrically remove the toner attached to the cleaning brush and the flat surface 25a. Further, the cleaning member 37 may be configured by a blade-shaped member.

In the above embodiment, the paper 5 is sucked by the paper suction unit 92 in order to press the paper 5 against the counter electrode 25. In the image forming apparatus as described above, the distance between the control electrode 26 and the sheet 5 greatly affects printing as described above. However, when plain paper or the like is used as the paper 5, in addition to the wrinkles, curls, and elasticity of the paper 5 itself, the paper 5 and the control electrode 26 or the counter electrode 25 The relative position changes. Although the variation is very small, since the distance between the control electrode 26 and the counter electrode 25 is very narrow, 1 mm or less, the relative distance from the control electrode 26 can vary greatly. If the position of the paper 5 changes, the shape and size of the dots to be printed may change and a desired image may not be formed, and the change in the shape and size of the formed dots may reduce the halftone reproducibility. As a result, an appropriate halftone cannot be obtained, and good image formation becomes difficult.

Further, when the position of the sheet 5 further changes, a case where the sheet contacts the control electrode 26 is caused. In this case, the toner already flying on the paper 5 is rubbed by the contact with the control electrode 26 to cause image destruction, and the toner attached to the control electrode 26 adheres to the paper 5 to cause fog, When the adhesion is severe, black streaks and black spots appear. When the paper 5 and the control electrode 26 come into contact with each other, electric charge is induced on the surface of the control electrode 26, and the surface of the control electrode 26 may have electric charge. In this case, since the charge on the surface of the control electrode 26 has a potential with respect to the control electrode 26, the apparent potential of the control electrode 26 as viewed from the toner 21 carried on the toner carrier 22 is the potential of the toner with respect to the control electrode 26. Accordingly, the potential changes to a potential different from a desired potential (the potential applied to the control electrode 26). Therefore, even if a potential for passing the toner through the gate 29 is applied to the toner, the flying of the toner is insufficient or the flying itself becomes difficult, resulting in an image dropout or poor printing, making image formation difficult. Further, even if an image is formed, the toner does not fly sufficiently, resulting in a blurred image in which contrast cannot be obtained. In addition, it is difficult to reproduce halftone.

Further, when the apparatus is placed in a high-temperature, high-humidity environment, the sheet 5 to be used absorbs moisture and the resistance is reduced, so that the control electrode and the counter electrode are conducted through the sheet 5. The high voltage of the counter electrode 25 is applied to the control electrode 26.
To the control electrode 25, the control circuit 26, and other devices, or other connected devices. In the worst case, it causes electric shock to the user. Therefore, it is an essential condition that the paper 5 is transported in a state where the paper 5 is in close contact with the counter electrode 25. For this purpose, it has been considered that the sheet 5 is conveyed while being attracted to the counter electrode 25 by electrostatic force using electrostatic attraction. However, while this method has a potential problem that the surface potential of the paper 5 tends to be unstable, a charging member or a charging power source for applying a charge to the paper 5 is required, so that the number of components is simply increased, and This leads to an increase in size and cost.

In the present embodiment, in order to avoid the above-mentioned problem, the paper suction unit 92 that suctions the paper 5 by air is used.
Plane 25a of the counter electrode 25, which has a very small friction with respect to
The paper 5 is conveyed while sliding.
The paper suction unit 92 has two fans 93a and 9 as pressure reducing means.
3b. As shown in FIG. 8, which is a top view of the paper suction unit 92, four chambers 96a to 96h and intake ports 94a to 94h are arranged to face the fans 93a and 93b, respectively. The fans 93a and 93b are the counter electrodes 2
5 is disposed both upstream and downstream in the transport direction of the paper 5.

As shown in the cross section of FIG. 7, the inlets 94a to 94h are provided with a slope at the portion of the chamber 96 where the inlets 94 are formed to prevent the leading end of the sheet 5 from entering the openings. And the air inlets 94b, 94d
The inclination is provided on the side surface of the counter electrode 25 as shown in FIG. The inclination prevents the leading end of the paper 5 from entering the air inlet 94, thereby preventing the paper 5 from jamming. Also, as shown in FIG. 2, each intake port 94 is on the same plane as the plane 25a of the counter electrode 25, and
The five flat surfaces 25a are brought into contact with each other. As shown in FIG. 4, the intake port 94 may be arranged at a position below the plane 25a (a position far from the control electrode 26). The intake port 94 may have a slit-shaped opening as shown in FIG. 8, but for example, as shown in FIG. 9, a plurality of circular openings 94j, 9
An aperture row composed of 4k may be formed.

If the intake port 94 is not in the form of a slit or a row of openings as described above, the openings may not always be able to appropriately face recording media of various sizes, and may cause poor suction. Nature occurs. In the above embodiment, the inlet 9
Since the slit 4 is formed, the intake port 94 can easily face any paper size, thereby avoiding one factor of poor suction.

The chambers 96a to 96h are arranged as shown in FIG. 8, and a horizontal sectional view of FIG. 8 is shown in FIG. As shown in FIG. 10, the chambers 96a, 96b and 96
The width L of e and 96f is the same as the width of a postcard which is the smallest sheet of the image forming apparatus. The chambers 96c and 96d and 96g and 96h are
When they are arranged beside a, 96b and 96e, 96f, the width becomes equal to the width of A4, which is the maximum paper size of the image forming apparatus.
Further, openings 97a to 97d and 97e of each chamber are provided.
To 97h are provided adjacent to each other as shown in FIG. 10, and are respectively arranged as shown in FIG. 11 so as to face the fans 93a and 93b as decompression means. FIG. 11 shows the paper suction unit 9.
It is sectional drawing seen from the front of 2.

With this arrangement, the intake port 94 and the chamber 96 are divided, and the opening 97 is
3 is arranged close to. In this way, when the paper 5 of various sizes is conveyed, and particularly when the small paper 5 is used and the suction port 94 is opened, the suction port 94 and the chamber 96 facing the paper 5 maintain the reduced pressure state. It is possible to obtain a good suction operation without lowering the suction force. If the chamber does not consist of multiple chambers,
When the small-sized paper 5 is carried in, air flows in from the suction port 94 which does not face the paper 5, and the pressure is not obtained at the suction port 94 facing the paper 5, so that the suction of the paper 5 is sufficiently obtained. However, this is not the case in the present embodiment. For example, as shown in FIG. 12, even when the paper 5 does not exist around the intake port 94 and there is no load on the chamber 96c, the pressure reduction effect is secured from the fan 93b to the opening 94a in the adjacent chamber 96a. The pressure in the chamber can be continuously reduced, and the sheet 5 can be stably sucked. In addition, as compared with the case where the chamber is divided and the decompression means is arranged in each chamber, the present embodiment can reduce the number of components such as fans and the size and cost of the apparatus.

The suction means using the above-described suction method includes:
It has been clarified that when the distance from the air inlet 94 to the sheet 5 is increased, the suction force is significantly reduced. Therefore, in order to ensure the suction of the paper 5, it is desirable that the paper 5 be brought close to the intake port 94 without curling. For this purpose, a guide member for guiding the paper 5 to the intake port 94 is arranged. It is preferred to do so. However, it is meaningless unless the guide guides the sheet 5 accurately to an area where an airflow capable of sufficiently sucking the sheet 5 with respect to the intake port 94 can be formed. For example, the guide 98 shown in FIG.
If the paper 5 is insufficiently guided and curls as in a, sufficient suction is not performed. Therefore, it is necessary that the guide is as shown in FIG. That is, the guide 98
The structure is such that the gap through which the paper passes becomes narrower toward the downstream of the paper transport so as to suppress the curl of the paper 5,
The tip of the guide 98b must reach a region where the suction force is sufficiently strong. The paper 5 is conveyed by the guide 98 in a state very close to the air inlet 94. The guide may be provided on the upstream side of each intake port 94, respectively.

In the above embodiment, the distance between the registration roller 95, the fixing means 11 and the air inlet 94 is smaller than the size of the paper 5. That is, since the distance between the registration roller 95 and the fixing unit 11 is smaller than the distance of the sheet 5, there is no need to separately provide a conveying roller as a conveying unit or a holding member for the sheet 5, and the simplest configuration as the conveying unit It becomes possible.

Further, since there is no member that may come into contact with the toner image before the toner image on the sheet surface after image formation is fixed, there is no possibility that image deterioration or image destruction occurs, and good image formation can be achieved. , It is possible to fix a good image as it is. In the above-described apparatus, a high-voltage driver or a high-voltage power supply for controlling the electric potential applied to the control electrode 26, a number of heat sources such as a drive motor, etc. are arranged, including the fixing unit 11. In particular, heat generated by the fixing unit 11 causes various problems as a main cause of increasing the temperature inside the apparatus. Conventionally, a cooling means for cooling heat generated from these heat sources is separately provided to cool the inside of the apparatus.

In the present embodiment, as described above, the air sucked from the air inlet 94 sucks the air inside the device from the region facing the control electrode 26 and discharges the air outside the device.
The inhaled air contains the electric circuit, the driving system and the fixing means in the flow path, and discharges the air containing heat from the electric circuit, the driving system and the fixing means to the outside of the apparatus. It is not necessary to separately provide a cooling means for cooling the apparatus, so that the number of parts can be reduced and the size and cost of the apparatus can be reduced.

Further, two fans 93a and 93b are arranged as in the above embodiment. If you use only a single fan, the required fan power is very high,
In addition to easily increasing the cost and increasing the size of the apparatus, the generated sound becomes extremely loud, which is not preferable. Therefore, it is appropriate to use an appropriate number of fans 93a and 93b in combination as in the above embodiment. Note that the number of fans to be used is not particularly limited to the above value.

Similarly, the air flow of the paper suction section 92 has the following characteristics. The fan 93, which is the above-described decompression means, continues to take air even while the counter electrode 25 is rotating between sheets. That is, even when the cleaning brush 25b is in contact with the control electrode 26 and the cleaning operation is being performed, the pressure in the chamber 96 is continuously reduced, and the suction from the suction port 94 is continued.

If the air intake is not performed during the cleaning operation as in the present embodiment, the following problems occur. The cleaning brush 25b is applied to the toner 21 attached to the control electrode 26 during the cleaning operation.
Directly contact with each other, a physical force acts. Therefore, not all of the cleaned toner 21 is retained by the cleaning brush 25b.
There is a possibility that the inside of the apparatus is soiled by scattering to the paper 5a or the paper 5 transport path, or the back surface of the paper 5 is stained by the toner adhered in the transport path.

However, in the above embodiment, the suction from the suction port 94 is continued while the toner 21 attached to the control electrode is cleaned, and the scattered toner 21 as described above is collected from the suction port 94 into the chamber. No trouble caused by the scattered toner 21 occurs. Further, as shown in FIG.
When the control electrode 26 is being rotated to clean the control electrode 26, the suction port 94e is enlarged to facilitate suction of the floating toner 21. The scattered toner and the floating toner as described above are likely to be generated in the case of paper jam or the like during the pre-rotation or post-rotation at the start of the operation of the apparatus. In these cases, it is preferable to perform the above suction.

In the above embodiment, a unit in which the counter electrode 25 and the paper suction means 92 are integrally formed is formed.
The above-described image forming apparatus has a feature that various processes can be omitted as compared with an image forming apparatus that uses an electrophotographic process that also uses toner. Therefore, the size of the apparatus can be greatly reduced. ing. Therefore, each of the parts is required to be very small and very high positional accuracy, and it is very high for parts replacement and cleaning in maintenance and the like or detachment of parts performed when paper jam is avoided. Skills and knowledge may be required. For this reason, a very ordinary user has to
It was very difficult to perform these tasks. However, in this embodiment, as shown in FIG.
Are unitized, so that the above operation can be easily performed by a general user.

In the present embodiment, the fans 93a, 93
b are arranged in the transport direction of the paper 5. In such an arrangement, the arrangement of the above embodiment is effective when a space in a direction perpendicular to the transport direction of the paper 5 is secured.
In the above embodiment, as shown in FIG.
The PCU board 99 and the ICU board 100 are arranged on both sides of b, so that heat generated from both boards can be guided to the intake port by the duct 101.

Also, as in the above embodiment, the fan 93
1a and 93b are arranged in parallel to the transport direction of the sheet 5 and upstream and downstream of the counter electrode 25, for example, as shown in FIG.
Even when the intake port 94 on the downstream side of the counter electrode 25 is open and there is no load as shown in FIG. 5, good suction can be obtained without lowering the efficiency of intake on the upstream side. Conversely, even when the sheet 5 exists only on the downstream side, good suction of the sheet 5 is also possible. In the above embodiment, the fans 93a, 93
An exhaust port b is provided below the device to exhaust the air in the device to the lower surface of the device. Therefore, the user can use the fans 93a, 93
There is no discomfort in the wind of b.

Further, since the sounds emitted from the fans 93a and 93b are softened as described above, it is possible to provide a silent effect. Similar effects can be obtained by disposing the fans 93a and 93b behind the apparatus and exhausting air from the rear of the apparatus. Further, in the above-described embodiment, the toner jumps from top to bottom, but may have a structure in which the toner jumps from bottom to top. In this case, the suction conveyance of the sheet 5 becomes indispensable, and the present invention can be applied more favorably.

Further, in the above embodiment, the fans 93a,
Although 93b is arranged before and after the counter electrode 25, if a powerful and quiet fan can be used, as shown in FIG.
5 may be arranged in parallel with the longitudinal direction. In this case, it is preferable to dispose the counter electrode 25 so as to be at the center of the fans 93a and 93b. In this case, even if the width of the paper 5 is arbitrarily changed for various paper 5 sizes, it is possible to perform good suction and conveyance of the paper 5 without lowering the suction performance.

Further, in this embodiment, the air guide 103 is arranged as shown in FIG. 11 so that the air from the fans 93a and 93b is not directly exhausted. Fan 9
As described above, the toner 21a is supplied to the air exhausted by 3a and 93b.
, The table and the like are not stained by the toner 21. In addition, the support 102 is further arranged on the lower surface of the apparatus so that the exhaust can be performed very efficiently. Further, the above-described embodiment may be configured such that the toner 21 flies upward from vertically downward as shown in FIG. 17, that is, the external exhaust passage 104 reaches the upper surface of the apparatus. In this case, the discharge tray 10
An opening for exhaust is provided on the fifth side. The discharge tray 105 has a configuration in which a protruding portion is provided at the tip end so that the opening is not closed as shown in FIG. The discharge tray also serves as an air guide. Further, a configuration may be employed in which the slit 106 is provided to smoothly exhaust air from the opening. With such a configuration, the discharge tray and the air guide can be used in common, and the number of components can be reduced, and the size and cost of the apparatus can be reduced.

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. Also, the case where the control electrode 26 has a configuration including the ring-shaped electrode 27 has been described as an example,
The control electrode 26 is not particularly limited to this configuration. For example, instead of providing the ring-shaped electrode 27, a plurality of strip-shaped electrodes are provided on both surfaces of the substrate 26a of the control electrode 26 so as to form a matrix (see FIG. 19), and the gate 29 is provided at a portion of the strip-shaped electrodes orthogonal to each other. Is provided. By controlling the voltage applied to the band-shaped electrode, the toner 21 from the toner carrier 22 to the opposite electrode 25 is controlled.
May be configured to control the flight of the airplane. In this case, the number of high-voltage drivers to be used can be significantly reduced, but the width of the control electrode 26 in the transport direction of the paper 5 becomes longer. The adsorption means becomes more effective.

In the above-described embodiment, a monochrome image forming apparatus has been described as an example. However, the present invention can further obtain the effect when a color image forming apparatus is used. For example, an image forming unit including a plurality of toner supply units and a printing unit may be arranged to form a color image forming apparatus using the respective toner supply unit color toners. In FIG. 20, image forming units 1a, 1b, 1c, and 1d corresponding to yellow, magenta, cyan, and black toners are arranged, and a color image is formed based on color image data. Other components may have the same configuration as in FIG.

Further, as shown in FIG. 21, paper suction portions 92a to 92d may be arranged in each toner supply portion. In the case of a color image forming apparatus, if the above-mentioned problem occurs, a desired dot diameter and density cannot be obtained because a desired toner flight cannot be obtained, and thus a new problem that appropriate color reproduction cannot be obtained. Invite. According to the present invention, the above-mentioned problems do not occur at all, so that desired color reproduction and good color image formation can be obtained.

In the case of a color image forming apparatus using a plurality of developing tanks as shown in FIGS. 20 and 21, the operations of developing and cleaning may be performed simultaneously. For example,
As shown in FIG. 21, when the development is performed in one color developing tank and the recording medium does not exist on the surface of the counter electrode facing the other color developing tank (for example, FIG. 21).
It is assumed that the control electrode facing the counter electrode is cleaned at 92d). The color toner of the color being cleaned may float in the atmosphere near the control electrode by a cleaning operation, for example, brush cleaning. In this case, the toner floating on the recording medium existing on the surface of the counter electrode during printing may fly due to the above-described cleaning, causing partial color fogging or color mixing. However, as described above, development is performed in one color developing tank, and there is no recording medium on the surface of the counter electrode facing the other color developing tank (for example, FIG. 2).
Suppose that the control electrode facing the counter electrode is cleaned at 92d). In this case, even if the color toner of the color being cleaned floats in the atmosphere near the control electrode by a cleaning operation, for example, brush cleaning, the paper suction unit 9 that is performing the cleaning operation
4d continues suction from the intake port, and the opening area of the intake port 94 increases during the cleaning operation as shown in FIG. Therefore, the floating toner is quickly sucked into the intake port 94 and does not fly toward the other counter electrode 25, and it is possible to partially avoid fogging and color mixing.

Further, the configuration of the toner supply unit 2 can 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.

[0093]

[Effect of the Invention The present onset bright image forming apparatus, by providing a separate conveying means and the counter electrode, airflow toward the air inlet of the nonexistent suction means for the recording medium is a developer of the carrier and the control electrode So that it is strong enough not to fly
Since the recording medium can be held and conveyed at a predetermined position even if the suction strength is restricted, the recording medium can be conveyed while maintaining a certain distance from the control electrode, and image defects due to contact with the control electrode and the like can be prevented. Occurrence can be prevented. Further, a counter electrode having an ideal plane for image formation can be used, and good image formation can be achieved.

[0094] This onset bright image forming apparatus, even if the leading end portion of the recording medium when the recording medium conveyance becomes likely enter the air inlet, the leading end of the recording medium to form the inclined surface abuts along the slope Since it returns to the original transport position, it is possible to prevent transport failure and paper jam with a very simple configuration.

[0095] This onset bright image forming apparatus, the counter electrode is accommodated in the chamber, so constituting a part of the inlet in the opposing electrode, the adsorption of the recording medium is obtained at a position closest to the opposite electrode, Good conveyance of the recording medium is obtained.

[0096] This onset bright image forming apparatus, the recording medium is to place the guide member in the area to be sucked into the intake port, it is possible to better suction conveyance without causing poor suction.

[0097] This onset bright image forming apparatus, since a plurality of chambers share a decompression means, it is possible to reduce the pressure in a small pressure reducing means, downsizing and cost reduction and apparatus parts can be reduced. Further, even if one of the plurality of chambers facing the decompression means is in an open state, the decompression of the other chambers is maintained, and good suction can be continued.

[0098] This onset bright image forming apparatus, since the decompression means and the chamber is arranged upstream and downstream of the counter electrode,
Even when the recording medium exists only at either the upstream or downstream of the counter electrode, good suction conveyance can be obtained without lowering the suction force.

[0099] This onset bright image forming apparatus, air inlet if so are arranged perpendicularly to the conveying direction of the pressure reducing means recording medium a narrow recording medium width is used is better in an open state Adsorption can be maintained.

[0100] This onset bright image forming apparatus, it is possible to suppress the loss of the adsorption can be opposed to accurately recording medium each chamber because the boundaries of the chamber to place the size of the recording medium to a minimum .

[0102] This onset bright image forming apparatus, running the adsorption means that is not used for image formation using the air flow toward the intake port, device, particularly the control electrode or developer floating in the vicinity of the counter electrode Can be easily recovered.
In addition, since the decompression means is always operated, high-temperature air can be sucked from the intake port, and the apparatus can be cooled, so that there is no need to provide a separate cooling means, thereby reducing the number of parts and miniaturizing the apparatus.・ Cost reduction becomes possible.

[0102] This onset bright image forming apparatus, by increasing the opening area of the intake port, the intake from the intake port is very smoothly, the intake port of the developer to be suspended in the device It is possible to improve the efficiency of the recovery of the wastewater.

[0103] This onset bright image forming apparatus, since the discharge tray of the exhaust port and a recording medium for exhausting air in the device are arranged on the same surface of the device on top can be downsized apparatus, the exhaust port Since the discharge tray also functions as a shielding member that prevents the discharge of the developer, the number of components can be reduced, and the size and cost of the apparatus can be reduced.

[0104] This onset bright image forming apparatus, since the suction means and the counter electrode constitute a single unit, requires only replacement of the unit for maintenance of the paper jam and devices,
Handling is simplified, and even a general user can easily maintain the apparatus.

[0105] This onset bright image forming apparatus, during printing, even in a region of a set of the carrier and the counter electrode is not performed the image forming operation, since it is possible to intake by vacuum means, scattering microscopy The image agent can be collected well, and color mixture and fogging due to the scattered developer can be avoided. By always operating the decompression means, high-temperature air can be sucked from the air inlet, and the equipment can be cooled, eliminating the need for additional cooling means, reducing the number of parts and reducing the size and cost of the equipment. Down becomes possible.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram illustrating an embodiment of a printer that is an image forming apparatus according to the present invention.

FIG. 2 is a main part configuration diagram centering on an image forming unit of the printer.

FIG. 3 is a configuration diagram of a control electrode.

FIG. 4 is an enlarged configuration diagram illustrating a paper suction unit.

FIG. 5 is a flowchart illustrating an image forming operation performed by the image forming apparatus.

FIG. 6 is a timing chart of a signal applied to a counter electrode.

FIG. 7 is an explanatory diagram showing an operation of cleaning the control electrode.

FIG. 8 is a top view of the paper suction unit.

FIG. 9 is a perspective view illustrating a paper suction unit in which an intake port forms an aperture row including a circular opening;

FIG. 10 is a cross-sectional view of the paper suction unit of FIG.

FIG. 11 is a longitudinal sectional view of an exhaust port portion of the paper suction unit.

FIG. 12 is an explanatory diagram showing exhaust when paper is transported in a part of a chamber.

FIG. 13 is an explanatory diagram showing an inappropriate example of a guide.

FIG. 14 is an explanatory view showing a guide of the present invention.

FIG. 15 is an explanatory diagram illustrating sheet conveyance when a fan is arranged upstream and downstream of a counter electrode.

FIG. 16 is a perspective view showing a paper suction unit in which a fan is arranged in a longitudinal direction of a counter electrode.

FIG. 17 is an overall configuration diagram of a printer in which a carrier is disposed on a lower side and a toner flies upward from below.

FIG. 18 is a perspective view of a paper discharge tray.

FIG. 19 is a configuration diagram showing another example of a control electrode.

FIG. 20 is a schematic configuration diagram illustrating a color image forming apparatus.

FIG. 21 is a main part configuration diagram showing another color image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming part 2 Toner supply part 3 Printing part 5 Paper 10 Paper supply part 11 Fixing part 22 Toner carrier 25 Counter electrode 26 Control electrode 27 Ring-shaped electrode 29 Gate 92 Paper adsorption part 93a, 93b Fan 94 Intake port 96 Chamber

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/385 G03G 15/05

Claims (13)

(57) [Claims] 1. A carrier for supporting a developer, a counter electrode arranged opposite to the carrier, and a plurality of members arranged between the carrier and the counter electrode and serving as a passage portion of the developer. A control electrode consisting of an electrode provided around the gate of the, a conveying means for conveying a recording medium for recording an image between the control electrode and the counter electrode, and between the carrier and the counter electrode The recording conveyed between the control electrode and the counter electrode by controlling the passage of the developer through the gate by applying a potential that causes a predetermined potential difference and changing the potential applied to the control electrode in the image forming apparatus and a control means for forming an image on a medium, comprising a chamber provided with an inlet in the vicinity of the opposite electrode, and a decompression means for decompressing the upper <br/> Symbol chamber, the pressure of the upper Symbol chamber the pressure reducing Depressurized by exhaust air by a step sucks the recording medium to said suction port, said control electric
Place the recording medium at a predetermined position between the pole and the counter electrode.
The gap between the suction means for suction holding and the chamber is downstream of the conveyance of the recording medium.
Formed so that it becomes smaller as going in the direction
In the area where the recording medium is sucked into the suction port,
An image forming apparatus, comprising: a guide member arranged so that an end is reached . 2. A carrier for supporting a developer, and the carrier
An opposing electrode disposed opposite to the carrier, the carrier and the opposing electrode,
Plural gates arranged between the poles and passing the developer
A control electrode comprising an electrode provided around
A recording medium for recording an image between the electrode and the counter electrode;
Conveying means for conveying, between the carrier and the counter electrode
And a potential that causes a predetermined potential difference
The developer is changed by changing the potential applied to the control electrode.
Controlling the passage of the gate to the control electrode
Form an image on the recording medium transported between the electrodes
In the image forming apparatus provided with a control means, an exhaust port and an intake port provided near the counter electrode are provided.
A plurality of girder chambers and
A pressure reducing means for reducing the pressure in the chamber;
The pressure inside the chamber is reduced by the pressure reducing means to exhaust the air.
The air is exhausted from the air port to reduce the pressure, and the recording medium is sucked into the air inlet.
A predetermined position between the control electrode and the counter electrode.
A suction means for sucking and holding the recording medium, and the exhaust ports of adjacent chambers are adjacent to each other.
Formed in the vicinity of the adjacent exhaust port.
Arrange one decompression means to reduce the pressure in each adjacent chamber.
An image forming apparatus, wherein pressure is made possible . 3. A carrier for supporting a developer, and the carrier
An opposing electrode disposed opposite to the carrier, the carrier and the opposing electrode,
Plural gates arranged between the poles and passing the developer
A control electrode comprising an electrode provided around
A recording medium for recording an image between the electrode and the counter electrode;
Conveying means for conveying, between the carrier and the counter electrode
And a potential that causes a predetermined potential difference
The developer is changed by changing the potential applied to the control electrode.
Controlling the passage of the gate to the control electrode
Form an image on the recording medium transported between the electrodes
An image forming apparatus provided with a control means, wherein a plurality of chambers provided with an air inlet near the counter electrode are provided.
And a pressure reducing means for reducing the pressure in the chamber.
The pressure inside the chamber is exhausted by the above-mentioned pressure reducing means.
To reduce the pressure and suck the recording medium into the intake port,
The recording is performed at a predetermined position between the control electrode and the counter electrode.
Comprising a suction means for attracting and holding a medium, the chamber and the pressure reducing means, pair the counter electrode
Then, upstream and downstream in the transport direction of the recording medium
An image forming apparatus , wherein each of the image forming apparatuses is provided . 4. A carrier for supporting a developer, and the carrier
An opposing electrode disposed opposite to the carrier, the carrier and the opposing electrode,
Plural gates arranged between the poles and passing the developer
A control electrode comprising an electrode provided around
A recording medium for recording an image between the electrode and the counter electrode;
Conveying means for conveying, between the carrier and the counter electrode
And a potential that causes a predetermined potential difference
The developer is changed by changing the potential applied to the control electrode.
Controlling the passage of the gate to the control electrode
Form an image on the recording medium transported between the electrodes
An image forming apparatus provided with a control means, wherein a plurality of chambers provided with an air inlet near the counter electrode are provided.
And a pressure reducing means for reducing the pressure in the chamber.
The pressure inside the chamber is exhausted by the above-mentioned pressure reducing means.
To reduce the pressure and suck the recording medium into the intake port,
The recording is performed at a predetermined position between the control electrode and the counter electrode.
A suction unit for sucking and holding the medium ; wherein the chamber and the pressure reducing unit are configured to carry the recording medium;
It is characterized by being arranged at right angles to the feeding direction
An image forming apparatus. 5. A carrier for supporting a developer, and said carrier
An opposing electrode disposed opposite to the carrier, the carrier and the opposing electrode,
Plural gates arranged between the poles and passing the developer
A control electrode comprising an electrode provided around
A recording medium for recording an image between the electrode and the counter electrode;
Conveying means for conveying, between the carrier and the counter electrode
And a potential that causes a predetermined potential difference
The developer is changed by changing the potential applied to the control electrode.
Controlling the passage of the gate to the control electrode
Form an image on the recording medium transported between the electrodes
In the image forming apparatus provided with the control unit, the suction unit has an intake port near the counter electrode.
Multiple chambers and reduced pressure to reduce the pressure inside the chamber
Means for reducing the pressure in the chamber to the pressure reducing means
The air is exhausted and decompressed, and the recording medium is suctioned.
Suction into the mouth and a predetermined distance between the control electrode and the counter electrode
Is provided with an adsorbing means for adsorbing and holding the recording medium at a position, and the boundary of the chamber is a recording medium which is conveyed.
Positions within the width of the recording medium and near both ends of the recording medium
An image forming apparatus , wherein the image forming apparatus is arranged so as to exist in the image forming apparatus. 6. The pressure reducing means other than when the recording medium is conveyed.
It is also possible to operate
5. The device according to claim 2, wherein the gas is exhausted outside the device.
Or the image forming apparatus according to 5 . 7. The size of the opening of the intake port is variable.
The image forming apparatus according to claim 6 , wherein the image forming apparatus is capable of functioning . 8. The air in the chamber is depressurized by the decompression means.
An external exhaust passage for exhausting outside the device by the
A discharge tray that covers the exhaust opening of the passage so as not to block it.
And a recording medium on which an image is formed is discharged onto the discharge tray.
The image forming apparatus according to claim 6 , wherein the image is output. 9. A carrier for supporting a developer, and said carrier
An opposing electrode disposed opposite to the carrier, the carrier and the opposing electrode,
Plural gates arranged between the poles and passing the developer
A control electrode comprising an electrode provided around
A recording medium for recording an image between the electrode and the counter electrode;
Conveying means for conveying, between the carrier and the counter electrode
And a potential that causes a predetermined potential difference
The developer is changed by changing the potential applied to the control electrode.
Controlling the passage of the gate to the control electrode
Form an image on the recording medium transported between the electrodes
An image forming apparatus provided with a control means, wherein a chamber provided with an air inlet near the counter electrode;
A pressure reducing means for reducing the pressure in the chamber.
The air in the chamber is exhausted by the above-mentioned pressure reducing means.
The pressure is reduced and the recording medium is sucked into the suction port, and the control
Place the recording medium at a predetermined position between the pole and the counter electrode.
A suction means for holding by suction is provided, and at least part of the counter electrode and the suction means is detachable.
An image forming apparatus characterized by being formed in a possible single unit . 10. A carrier for carrying a developing agent, and said carrier
A counter electrode disposed opposite to the body, and the carrier and the counter electrode
A plurality of gates arranged between the electrodes and
Control electrode consisting of an electrode provided around the
Recording medium for recording an image between a control electrode and the counter electrode
Transport means for transporting the carrier and the counter electrode
Apply a potential that causes a predetermined potential difference between
Visualization by changing the potential applied to the control electrode
Controlling the passage of the agent through the gate so that the control electrode and the pair
Forming an image on the recording medium transported between the counter electrodes.
An image forming apparatus comprising: a chamber having an intake port near the counter electrode;
A pressure reducing means for reducing the pressure in the chamber.
The air in the chamber is exhausted by the above-mentioned pressure reducing means.
The pressure is reduced and the recording medium is sucked into the suction port, and the control
Place the recording medium at a predetermined position between the pole and the counter electrode.
An adsorbing means for adsorbing and holding, wherein the carrier and the counter electrode are provided with a plurality of color developing agents;
And one set where no printing operation is performed.
In the area between the support and the counter electrode described above,
An image forming apparatus characterized in that intake can be performed by steps . 11. The transfer means comprises: the counter electrode;
The direction of conveyance of the recording medium with respect to the area facing the control electrode
Located upstream between the control electrode and the counter electrode
Supply and transport means for supplying the recording medium, and the control electrode
And transport of the recording medium to the facing area of the facing electrode
The control electrode and the counter electrode are arranged on the downstream side in the direction.
Discharge conveyance means for discharging the recording medium from between
And the suction unit includes the supply and conveyance unit and the discharge and conveyance unit.
Between the supply and conveyance means and the discharge and conveyance means,
Arranged so that it is shorter than the length of the recording medium in the conveyance direction.
The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed . 12. At least in a conveying direction of the recording medium.
Intake direction so as to narrow the intake port
12. The method according to claim 1, wherein a slope is formed in the groove.
An image forming apparatus according to any of the preceding claims . 13. The suction means is open to the chamber.
An opening is provided, and at least a part of the counter electrode is provided in the opening.
And the opening other than the storage part is used as the intake port.
The image forming apparatus according to claim 1, wherein: