JPH10202935A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which is capable of stably sucking a recording paper to an opposite electrode side and sending the recording paper without vibrating it. SOLUTION: This image forming device forms and image on a recording paper 5 by controlling the scattering orbit of a toner scattering toward an opposite electrode 25. In addition, the device is equipped with a support face 25a which is flush with the main face 25a of the opposite electrode 25 and supports 94A-94D which support the recording paper 5 with the support face 25a having a suction aperture opened, and suction means (96, 93-1, 93-2) which suck a recording medium 5 on the support face 25a through sucking from the suction aperture. Further, on the support face 25a, plural grooves are formed in parallel with a direction in which the recording paper 5 is fed with a paper feed means 95 and at downstream side in the paper feed direction. These grooves reduce a contact area between the recording paper 5 and the support face 25a so that the frictional resistance is diminished to achieve a smooth paper feed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital copying machine or facsimile machine, or a digital printer or plotter.

[0002]

2. Description of the Related Art Recently, as an image forming apparatus for outputting an image signal as a visible image on a recording medium such as recording paper, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 5-134581,
2. Description of the Related Art An image forming apparatus has been proposed which directly forms a toner image on a recording medium by applying an electric field to toner, which is a developer, and causing the toner to fly by electric force to control the flight trajectory of the toner.

That is, the above-described apparatus forms an electric field between a developing sleeve, which is a developer carrier, and a counter electrode, and causes the toner to fly by the electric field. The flying trajectory of the toner is controlled by switching between a potential that does not pass the toner and a potential that does not pass the toner in accordance with the image data to a control electrode disposed between the developing sleeve and the counter electrode. A toner image is formed on the surface of the recording paper.

[0004]

As described above, in an image forming apparatus of the type in which an image is formed directly on a recording medium by flying toner, the distance between the control electrode and the counter electrode is fixed. It is desirable that the distance between the control electrode and the recording medium be kept constant, which is a condition for performing good image formation.

However, since the distance between the control electrode and the counter electrode is very small, for example, about 1 mm, when plain paper is used as a recording medium, wrinkles and curls of the recording medium, elastic force, etc. The relative position of the recording medium with respect to the control electrode or the counter electrode changes depending on the electric force applied to the recording medium. As a result, the shape and size of the dots of the image on the recording medium change, the reproducibility of halftone is reduced, and it becomes difficult to form a good image.

[0006] If the position of the recording medium changes further, the recording paper may come into contact with the control electrode. In this case, the toner adhering to the recording medium is rubbed by contact with the control electrode to cause image destruction, and the toner adhering to the control electrode adheres to the recording medium to cause fogging, and causes black streaks and black spots. May appear.

When the recording medium comes into contact with the control electrode,
In some cases, electric charges are induced on the surface of the control electrode to charge the surface of the control electrode. In this case, the apparent potential of the control electrode as viewed from the toner carried on the toner carrier (sleeve) changes. As a result, even if an electric potential that does not allow the toner to pass through the gate is applied, the toner does not fly properly, resulting in a missing image or poor printing. Further, even if an image is formed, if the toner does not fly properly, the contrast is reduced, the image is blurred, and the reproducibility of halftone is reduced.

Further, when the device is placed in a high-temperature, high-humidity environment, when the recording medium to be used absorbs moisture and the electric resistance is lowered, conduction between the control electrode and the counter electrode through the recording medium. In this state, the high voltage of the counter electrode leaks to the control electrode side, and causes destruction of the device.

Therefore, in order to avoid such a problem, the counter electrode is formed in a roller shape, and the recording paper is attracted to the roller-shaped counter electrode to stably determine the position of the recording paper. There is something. That is, this counter electrode is made of a roller having a mesh-shaped opening,
The roller is provided with a pressure reducing means for adsorbing the recording paper. The air is sucked from the mesh-shaped opening by the depressurizing means to adsorb the recording medium to the roller (counter electrode). Then, the rollers (counter electrodes) rotate and transport the recording paper while adsorbing it.

However, when the counter electrode is formed in a roller shape as described above, although it is convenient for transporting the recording medium, the surface of the recording paper is curved, and the distance between the control electrode and the recording paper is not uniform. For this reason, the shape and density of the dots formed at the center and the end of the control electrode are different,
In particular, at the end, not only the dot density is reduced but also the dot diameter is reduced, making it difficult to form an appropriate dot.
As a result, not only the contrast is reduced and the image is blurred, but also the reproducibility of halftone is reduced, and in the case of a color image forming apparatus, it is difficult to faithfully reproduce colors.

In this case, the potential applied to the control electrode may be changed so as to compensate for the difference in the distance between the control electrode and the recording paper. However, since a plurality of types of potentials are required,
The cost increases because the number of power supplies increases and the withstand voltage of the driver used for switching the potential needs to be increased.

In order to avoid the above-mentioned problems caused by forming the counter electrode in a roller shape, the counter electrode is formed in a belt shape, and the recording medium is charged so as to be electrostatically attracted to the belt. Attempts have been made to use an electrostatic suction transport method for transport. However, according to this method,
The number of parts increases due to the need for the belt and belt driving means, charging means for the recording medium, charging power supply, etc., which not only causes a significant cost increase, but also cannot be absorbed due to environmental changes or the material of the recording medium. In particular, there is a fatal problem such that adsorption itself becomes difficult because the surface potential easily changes particularly depending on the thickness and the resistance value.

Therefore, as a method for avoiding the above-mentioned various problems, there is an air suction conveyance method in which a recording medium is conveyed while sliding on the counter electrode having a flat surface while air is suctioned. However, in this method, since the recording paper is slid in a state where the air is sucked, there is a problem that the recording paper vibrates due to a frictional force. When the recording medium vibrates, the recording medium separates from the suction port for air suction, and the suction force of the recording medium extremely decreases. As a result, the recording medium rises with respect to the counter electrode, and the position of the recording medium changes, thereby causing the above-described image degradation.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and enables a recording paper to be stably conveyed by being attracted to a counter electrode side and stably adsorbed regardless of environmental changes. It is an object to provide an image forming apparatus capable of forming an image by causing the image forming apparatus to form an image.

[0015]

Means for Solving the Problems The present invention has the following arrangement to achieve the above object. That is, claim 1
The image forming apparatus according to the invention described in (1), a toner carrier that carries toner, a counter electrode that is disposed to face the toner carrier and forms an electric field between the toner carrier, and a function of the electric field. A control electrode disposed on a flight trajectory of the toner which receives the toner and travels from the toner carrier toward the counter electrode; and a paper feeding means for feeding a recording paper onto a main surface of the counter electrode; An image forming apparatus for forming an image on the recording paper by controlling the potential of the control electrode based on the support surface, the support surface being substantially the same as the main surface of the counter electrode, and an air inlet opening to the support surface Is formed, a support for supporting the recording paper on the support surface, and suction means for sucking air through the air inlet to adsorb the recording medium to the support surface, wherein the support surface has The recording paper with respect to the paper feeding means. The dispensing direction parallel to the plurality of grooves on the downstream side of the feeding direction have a configuration of an image forming apparatus, wherein a is formed.

Further, in the image forming apparatus according to the present invention, a plurality of suction ports are formed in a direction in which the recording paper is fed or a direction orthogonal to the feeding direction. It has a configuration of the image forming apparatus described in 1.

Further, in the image forming apparatus according to the third aspect of the present invention, the groove is formed on the downstream side in the recording paper sending direction with respect to the intake port. An image forming apparatus according to any one of the above aspects.

According to a fourth aspect of the present invention, in the image forming apparatus, the air inlet is formed so as to communicate with the groove. It has a configuration of an image forming apparatus.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, a slope is provided on a wall on one end side of a groove located on a downstream side in a recording paper sending direction. 4. The image forming apparatus according to any one of 4.

The present invention configured as described above operates as follows. That is, according to the image forming apparatus of the first aspect, the recording paper is sent out onto the main surface of the counter electrode by the paper feeding means while being supported by the support surface of the support. Further, the suction means sucks air from an air inlet opening on the support surface to suction the recording paper onto the support surface of the support. For this reason,
The recording paper is sent out while being attracted to the support.

At this time, the friction between the recording paper and the support surface is increased by suction by the suction means, but a groove is formed on the support surface in parallel with the recording paper sending direction. The contact area between the recording paper and the support surface is reduced. As a result, the recording paper is sent out with the friction reduced.

According to the image forming apparatus of the present invention, the recording paper is sucked in the direction in which the plurality of air inlets are arranged.

According to the image forming apparatus of the third aspect of the present invention, the suction end of the leading end side of the recording paper becomes ineffective after passing through the suction port, and becomes unstable. Is formed on the downstream side in the feeding direction with respect to the intake port, so that the friction between the leading end portion of the recording paper in an unstable state and the support is reduced, and the recording paper is fed without vibrating. .

Further, according to the image forming apparatus of the present invention, since the groove communicates with the suction port, the suction by the suction means is also performed from the groove, and the recording paper is formed by the suction port and the groove. Adsorbed.

Further, according to the image forming apparatus of the present invention, since one end of the groove is formed with an inclination, even if the leading end of the recording paper enters the groove, the recording paper can be sent out. Is not inhibited.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in order with reference to FIGS. In each of the drawings, common or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted. In the following description, an image forming apparatus configured to support a negatively charged toner will be described in detail. However, when a positively charged toner is used, the polarity of each applied voltage is appropriately adjusted accordingly. What is necessary is just to set and configure.

As shown in FIG. 1, the image forming apparatus according to the present embodiment includes an image forming unit 1 having a toner supply unit 2 and a printing unit 3, and a paper input side and a paper output side of the image forming unit 1. On the sides, a paper feeder 10 and a fixing unit 11 are provided, respectively. Here, as described later, the image forming unit 1 causes the toner 21 as the visualized particles to fly by electric force, controls the flight trajectory based on the image signal, and records the recording paper 5 as a recording medium. An image (toner image) is formed directly on the substrate.

The paper feeding device 10 includes a recording material cassette 4 for storing recording paper 5 as a recording medium, and a pickup roller 6 for feeding the recording paper 5 from the recording material cassette 4.
And a paper feed guide 7 for guiding the recording paper 5, and a pair of registration rollers 95 for feeding the recording paper 5 (paper feeding means)
And a paper feed sensor (not shown) for detecting whether or not the recording paper 5 has been supplied. The pickup roller 6 is driven to rotate by a driving device (not shown), and takes out the recording paper 5 one by one from the paper feeding device 10 to remove the recording paper 5 one by one.
Give to.

Further, the fixing unit 11 includes a heating roller 12
, Heater 13, pressure roller 14, temperature sensor 15
And a temperature control circuit 16. The image forming unit 1 heats and presses the toner image formed on the recording paper 5 to fix it on the recording paper 5. Here, the heating roller 12 is made of, for example, an aluminum tube having a thickness of 2 mm. The heater 13 is
For example, it is formed of a halogen lamp and is built in the heating roller 12. The pressure roller 14 is made of, for example, a silicone resin.

Heating rollers 12 provided opposite to each other
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 pressure roller 14 is pressed with the recording paper 5 therebetween. Further, the temperature sensor 15 measures the temperature of the surface of the heating roller 12. The temperature control circuit 16 controls ON / OFF of the heater 13 based on the measurement result of the temperature sensor 15 and keeps the temperature of the surface of the heating roller 12 at, for example, 150 ° C. In addition,
The fixing unit 11 includes a paper discharge sensor (not shown) that detects whether the recording paper 5 has been discharged.

Although not shown, a discharge roller for discharging the recording paper 5 fixed by the fixing unit 11 onto a discharge tray is provided on the paper output side of the fixing unit 11, and the discharged recording paper 5
Receiving tray is provided. The material of the heating roller 12, the heater 13, the pressure roller 14, and the like, or the surface temperature of the heating roller 12 is not limited to the above example. A configuration may be adopted in which the toner image is fixed on the recording paper 5 by any of them.

Next, the image forming section 1 will be described in detail. The toner supply unit 2 constituting the image forming unit 1 includes:
A toner container 20 for storing toner 21 as visualized particles, and a cylindrical toner carrier 2 for carrying toner 21
2 (sleeve), and a doctor blade 23 that negatively charges the toner 21 and regulates the thickness of the toner layer carried on the outer peripheral surface of the toner carrier 22.

The toner carrier 22 is grounded and is driven by a driving device (not shown) to rotate in the direction of arrow A in the figure at a speed of, for example, 100 mm / sec on its surface.
The doctor blade 2 is provided inside the toner carrier 22.
A magnet (not shown) is disposed at a position facing the control electrode 3 and a control electrode described later.
The toner 21 is raised on the outer peripheral surface and is magnetically carried. Although the toner 21 is carried by magnetic force, the toner 21 may be carried by electric force or electric force and magnetic force.

The doctor blade 23 holds the toner carrier 2
An upstream side in the rotation direction 2 is provided at a distance of, for example, 60 μm from the outer peripheral surface of the toner carrier 22, and the thickness of the toner layer is regulated according to this distance. Toner 21
Is a magnetic toner having an average particle diameter of 8 μm, for example, and has a charge amount of −4 μC / g by the doctor blade 23.
The electric charge is applied so as to be -10 C / g. Note that the distance between the doctor blade 23 and the toner carrier 22, or the average particle size or charge amount of the toner 21 is not limited to the above example.

On the other hand, a printing unit 3 constituting the image forming unit 1
Is a counter electrode 25 facing the outer peripheral surface of the toner carrier 22.
And a power supply 30 for supplying a high voltage to the counter electrode 25, a control electrode 26 provided between the toner carrier 22 and the counter electrode 25, and a recording paper suction mechanism (no symbol). Be composed.

Here, the counter electrode 25 is formed of a semi-cylindrical aluminum tube having a thickness of 1 mm and having a flat portion 25a (main surface of the counter electrode) on a part of the outer peripheral surface. The flat portion 25a of the counter electrode 25 has a low volume efficiency of 10 ⁸ Ω · c.
A fluorine coating layer 25c having a thickness of 75 μm and a thickness of 75 μm is formed, and its frictional resistance is reduced.

The counter electrode 25 is disposed such that the flat portion 25a is located at a distance of, for example, 1.1 mm from the outer peripheral surface of the toner carrier 22, and a high voltage of, for example, 2 kV is applied by the power supply 30. As a result, an electric field necessary for causing the toner 21 carried on the toner carrier 22 to fly toward the counter electrode 25 is formed between the toner carrier 22 and the counter electrode 25 (the flat portion 25a).

A cleaning brush 25b is mounted on the curved surface of the counter electrode 25. When the counter electrode 25 is rotated by a driving device (not shown), toner adhered to the control electrode 26 by the cleaning brush 25b is removed. to clean up. A second cleaning brush 37 supported by a support member 38 is provided near the cleaning brush 25b.
b. The toner attached to b is removed. This second cleaning brush 3
7, the same potential as that of the counter electrode 25 is always applied during the image forming operation.

Next, the above-mentioned control electrode 26 is
5 is two-dimensionally spread so as to be parallel to the flat surface portion 25 a of the fifth member 5, and has a structure in which a toner flow flying from the toner carrier 22 toward the counter electrode 25 can pass. The electric field formed between the toner carrier 22 and the counter electrode 25 changes according to the potential supplied to the control electrode 26, and the toner 2 from the toner carrier 22 to the counter electrode 25 changes.
One flight trajectory is controlled.

As shown in FIG. 2, the control electrode 26 includes an insulating substrate 26a, a high-voltage driver (not shown), an independent ring-shaped electrode 27,
8 from the outer peripheral surface of the toner carrier 22
It is fixed by a support member (not shown) at a distance of 00 μm. Here, the substrate 26a is made of an insulating base material such as a polyimide resin and has a thickness of, for example, 25 μm. The substrate 26a has a plurality of holes to be gates 29 described later. The ring-shaped electrode 27 and the power supply line 28 are covered with an insulating layer (not shown), and electrical insulation therebetween is ensured.

The ring-shaped electrodes 27 are made of, for example, copper foil, and are arranged in a predetermined arrangement on one surface of the substrate 26a facing the toner carrier 22 so that the openings are located in the holes. I have. The ring-shaped electrode 27 has, for example, an outer diameter of 220 μm, a thickness of 30 μm, and an opening diameter of 200 μm. The opening of the ring-shaped electrode 27 serves as a passage for the toner 21 flying from the toner carrier 22 to the counter electrode 25.
Hereinafter, this passing portion is referred to as a gate 29.

The gate 29 has a resolution of, for example, 300 DPI (Dot Per Inch) in the width of A4 size recording paper.
In this case, about 2560 electrodes are formed, and the ring-shaped electrodes 27 of each gate are electrically connected to the control power supply unit 31 via the power supply line 28 and a high-voltage driver (not shown).
The number and size of the gates 29, the distance between the control electrode 26 and the toner carrier 22, the thickness of the ring-shaped electrode 27, and the like are not limited to the above examples.

A pulse voltage corresponding to an image signal is applied to the ring-shaped electrode 27 by a control power supply section (control means) 31 shown in FIG. For example, when the control power supply unit 31 allows the toner 21 carried on the toner carrier 22 to pass through the ring-shaped electrode 27 in the direction of the counter electrode 25, for example,
When 150 V is applied and not passed, for example, -20
0 V is applied.

As described above, when the recording paper 5 is sent to the flat portion 25a of the counter electrode 25 and transported while controlling the potential applied to the control electrode 26 (ring-shaped electrode 27) based on the image signal, the recording paper 5 A toner image corresponding to the image signal is formed on the surface of the toner image. The control power supply unit 31 is controlled by a control electrode control signal sent from an image forming control unit (not shown), as described later. In addition,
As described above, a recording paper suction mechanism (no reference numeral) is provided around the counter electrode 25.
Details will be described later.

Although not shown, the present image forming apparatus comprises:
As a control circuit, a main control unit that controls the entire image forming apparatus, an image processing unit that converts 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 information memory that stores the 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.

Next, the copying operation of the digital copying machine as the image forming apparatus as described above will be described with reference to the flowchart shown in FIG. First, in FIG. 1, when a user places a document to be copied on an image reading unit (not shown) and operates a copy start button (not shown), the image reading unit starts an operation of reading an image from the document. (Step S01). Image data obtained by reading an image of a document by the image reading unit is subjected to image processing by an image processing unit (not shown) (step S02), and is stored in an image memory (not shown) (step S03).
This image data is further transferred to an image formation control unit (not shown) (step S04), and is converted into a control electrode control signal (step S05).

When the image forming control unit obtains a predetermined amount of control electrode control signals (step S06; YE)
S), the driving device (not shown) is controlled to start the rotation of the toner carrier 22 (sleeve) of the image forming section 1 (step S08), and -200 V is set to the shield electrode (not shown) of the control electrode shown in FIG. (Step S09),
A predetermined high voltage is applied to the counter electrode 25 to activate the recording paper suction mechanism (step S10).

Next, the pickup roller 6 of the sheet feeding device 10 shown in FIG.
Take out. The picked-up recording paper 5 is sent out to the image forming unit 1 by the registration roller 95, and is fed at a predetermined speed onto the flat portion 25a of the counter electrode 25 while being attracted by the recording paper attracting mechanism. If the paper feeding is normally performed (step S12; YES), the image forming control unit supplies a control electrode control signal to the drive circuit 31 shown in FIG. 1 at a timing synchronized with the feeding (conveyance) of the recording paper 5. . The drive circuit 31 applies a drive signal (image control potential) to the control electrode 26 in accordance with the supplied control electrode control signal (step S14), controls the flying trajectory of the toner flow, and
To form (print) a toner image. The predetermined amount of the control electrode control signal varies depending on the configuration of the image forming apparatus.

This toner image is pressurized while being heated by the fixing unit 11 shown in FIG.
The sheet is discharged onto a sheet discharge tray by a sheet discharge roller. Then, the paper ejection sensor detects that the paper has been normally ejected, and when it is determined that the printing (image forming operation) has been completed normally (step S15; YES), the process returns to step S01 described above and returns to step S01. Move to the reading operation of the original.

Next, the control operation of the counter electrode 25 will be described.
An explanation will be added with reference to FIG. Here, FIG. 4 shows a signal waveform for controlling the driving of the counter electrode 25 between papers of the present apparatus. In the drawing, t indicates a printing interval, that is, a sheet interval. When the operation of forming an image on one recording sheet 5 is completed, the counter electrode 25 is controlled so as to make one rotation in a time T shorter than the time t.
The opposite electrode 25 has a high voltage (2
kV).

This high voltage, as shown in FIG.
Is switched to a low voltage (-500 V) during the period. That is, the potential of the cleaning brush 25b is reduced by the switching unit 30c shown in FIG.
V). The potential of the cleaning brush 25b is switched again to the potential (2 kV) of the power supply 30a necessary for the printing operation (flying toner) at the end of the driving of the counter electrode 25.

During the printing operation (during the image forming operation),
The plane 25a of the counter electrode 25 always faces the control electrode 26 in parallel, but during the non-printing operation, particularly during the sheet interval (the period of time T shown in FIG. 4), as shown in FIG.
5 makes one rotation. In the course of this rotation, the cleaning brush 25b comes into contact with the control electrode 26 and cleans the toner adhered to the control electrode 26.

In the course of this cleaning, the cleaning brush 25
The electric field applied to the toner 21 adhering to the control electrode 26 from the tip of b is much stronger than that of printing, so that the toner that has not been attracted to the counter electrode 25 during the printing operation is attracted to the cleaning brush 25b. Then, the control electrode 26 is more effectively cleaned. Further, as described above, since the potential of the cleaning brush 25b is switched at the time of cleaning, the toner charged to the opposite polarity is also cleaned.

The cleaning brush 25b finally separates from the control electrode 26 as the counter electrode 25 rotates, and
Again makes the plane portion 25a face the control electrode 26 in parallel and stops the rotation. The second cleaning means 37 includes the counter electrode 2
While rotating 5, the cleaning brush 25b contacts the cleaning brush 25b and the flat surface 25a to clean toner adhered to the flat surface 25a and the cleaning brush 25b.

Next, the recording paper suction mechanism for sucking the recording paper 5 will be described in detail. As shown in FIG. 1, the recording paper suction mechanism includes a chamber 96, supports 94A to 94D supporting the recording paper 5, and fans 93-1 and 93-2 for exhausting air from the chamber 96. Become. Here, the chamber 96 houses the counter electrode 25. The supports 94A and 94B are disposed upstream of the counter electrode 25 in the direction in which the recording paper 5 is sent out.
C and 94C are provided on the downstream side.

A support surface is formed on each of the supports 94A to 94D so as to be flush with the plane portion 25a of the counter electrode 25, and a plurality of intake ports 94-94 communicate with the support surface. 1 to 94-4 are formed, and the air inside the chamber 96 is exhausted by the fans 93-1 and 93-2, and the recording paper 5 is sucked to the support surface by sucking the air through the air inlet. The periphery of the intake port is configured to be planar. Further, a guide 98 for guiding the recording paper 5 onto the support 94A is disposed upstream of the air inlet 94-1. In the apparatus shown in FIG. 1, the plurality of air inlets are arranged in the direction in which the recording paper 5 is sent out, but may be arranged in a direction orthogonal to the direction in which the recording paper is sent out.

Here, as shown in cross sections in FIG. 1 and FIG. 7 described later, each of the intake ports 94-1 to 94
The opening of the recording paper 5 is provided with an inclination to prevent the leading end of the recording paper 5 from entering the opening. Prevent jam of 5.

The support surface of each support is provided with a counter electrode 25.
The recording paper 5 is adhered to the flat surface 25a of the counter electrode 25 by adsorbing the recording paper 5 on the support surface. However, these support surfaces correspond to the counter electrode 25.
In order to increase the degree of adhesion between the counter electrode 25 and the recording paper 5, the counter electrode 25 may be disposed at a position farther from the control electrode 26 than the flat portion 25a of the counter electrode 25.

Next, grooves are formed in the support surfaces of the supports 94A to 94D as shown in FIGS.
Here, FIG. 6 shows a cross section of each support in a direction perpendicular to the recording paper feeding direction, and FIGS. 7 and 8 show cross sections of the recording paper in the feeding direction. As shown in FIGS. 6 and 7, grooves 104B and 104C are formed on the support surfaces of the supports 94B and 94C located downstream of the intake ports 94-1 and 94-3, respectively, in parallel with the recording paper sending direction. Support 94D formed downstream of the inlet 94-4.
A groove 104 </ b> D communicating with the intake port 94-4 is formed on the support surface of the air inlet 94-4.

The recording paper 5 is formed by the grooves 104B to 104D formed in the supports 94B to 94D located downstream of the registration roller 95 (paper feeding means).
As a result, the frictional resistance between the recording paper 5 and the support surface is reduced. This allows
When the recording paper 5 is transported, the recording paper 5
Vibration is suppressed.

As shown in FIG. 7 and FIG.
The depth of each of 4B and 104C is formed shallower toward the downstream side in the feeding direction of the recording paper 5 (the depth becomes shallower as approaching the air inlets 94-2 and 94-4), and finally connected to the support surface. Eliminates the step with the intake port.
Therefore, even if the leading end portion of the recording paper 5 enters the groove, no trouble (jam) occurs in feeding the recording paper 5, and the recording paper 5 can be transported reliably. In the above-described example, the groove is formed to be shallower toward the downstream side in the feeding direction of the recording paper 5. However, an inclined wall is provided on one end side of the groove located downstream in the feeding direction of the recording paper 5. May be configured.

Further, as shown in FIG. 8, since the groove 104D is connected to the intake port 94-4, an air flow is formed from the groove 104D to the intake port 94-4. In addition, the suction force can be applied to the recording paper 5 over the entire length of the groove 104D, and the recording paper 5 can be suctioned over a wider range.

The intake ports 94-1, 94-3, 94-
4, grooves 104B, 104C, 104
Since D is arranged, in the air suction conveyance method, the vibration of the recording paper 5 is avoided, good paper suction can be performed, and good image formation can be performed. The groove of each support is
Since the ABS resin can be formed by integral molding, the number of parts can be reduced and the cost can be reduced.

When the recording paper 5 is separated from the supporting surface, the suction force hardly acts, and the recording paper 5 cannot be suctioned. Therefore, in order to ensure the suction of the recording paper 5, it is desirable to bring the recording paper 5 close to the suction port 94-1 at the time of feeding (conveying). Therefore, the recording paper 5 is guided to the suction port 94-1. It is desirable to dispose a guide member 98 that performs the operation. Further, by forming the periphery of the suction port 94-1 in a flat shape, when the recording paper 5 is in the suction state, air does not leak from the suction port 94-1 and the suction force does not decrease.

Further, the case where the control electrode 26 has a configuration including a ring-shaped electrode 27 as shown in FIG. 2 has been described as an example, but the configuration of the control electrode 26 is not limited to this. is not. For example, as illustrated in FIG.
A so-called matrix-type control electrode formed by crossing a plurality of strip-shaped electrodes on both surfaces of the substrate 26a may be used.

When this matrix type control electrode is used, the number of high voltage drivers to be used can be greatly reduced, but the width of the control electrode 26 (length in the transport direction of the recording paper 5) becomes large. Therefore, it is desirable to use the suction method as in the present embodiment, in which the suction is performed also by the groove formed in the transport direction.

In the above description, a monochrome image forming apparatus is taken as an example. However, the present invention can obtain more remarkable effects in, for example, a color image forming apparatus as shown in FIG. That is, in general, in the case of a color image forming apparatus, it is necessary to apply a plurality of types of developing agents with high accuracy. Can not be obtained.

In this regard, according to the apparatus of this embodiment, the recording paper can be stably conveyed while suppressing the vibration while keeping the positional relationship with the control electrode constant. Can be accurately attached to the surface of the substrate.
Therefore, desired color reproducibility can be obtained, and a good color image can be formed.

Here, the color image forming apparatus shown in FIG. 10 includes a plurality of image forming units 1a to 1d corresponding to the image forming unit 1 shown in FIG. Each of the image forming units 1a to 1 is, for example, yellow, magenta,
A color image is formed using cyan and black toners, and a color image is formed by superimposing images of respective toners based on a color image signal.

Although the image forming section 1 makes the toner fly toward the recording paper by electric force, for example, a latent image is formed on a recording medium using corona ions emitted from an ion source such as a corona charger. The so-called ion flow method for forming the above may be used. The apparatus of the present embodiment is, for example, a digital copying machine or a facsimile machine,
Alternatively, it can be widely realized as a digital printer, a plotter, or the like. Further, the case where the developer is a toner has been described as an example, but the developer may be an ink or the like. Further, a registration roller 95 as a paper feeding means is provided.
May be arranged along the conveyance path of the recording paper 5.

[0071]

As is apparent from the above description, according to the present invention, the following effects can be obtained. That is, according to the first and second aspects of the present invention, since the grooves are formed in the recording paper conveyance path (support surface), the recording paper is conveyed by sucking (pressing) the conveyance path or the counter electrode. Can reduce or eliminate the vibration of the recording paper,
It is possible to form a high-quality image having excellent halftone reproducibility and color reproducibility.

Further, according to the third aspect of the present invention, since the groove is formed on the downstream side of the air inlet, the vibration of the leading end of the recording paper can be prevented. According to the fourth aspect of the present invention, since the groove formed on the support surface communicates with the intake port, the air flow in this groove is ensured, and the recording paper can be sucked over a wide range. The recording paper can be supported more stably. According to the fifth aspect of the present invention, even if the leading end of the recording paper enters the groove, the recording paper can be smoothly guided to the air inlet, and jamming of the recording paper can be prevented.

Therefore, according to the present invention, since the air suction system is employed, the paper can be suctioned by a simple system. In addition, since the periphery of the air inlet is formed by a flat surface, the pressure reduction for adsorbing the sheet can be performed more efficiently. Further, since the grooves are formed on the recording paper transport path, there is no need to provide a separate transport path, so that the number of components can be reduced and the size and cost of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an image forming apparatus of the present invention.

FIG. 2 is a top view of a control electrode included in the image forming apparatus of the present invention.

FIG. 3 is a flowchart for explaining an image forming operation of the image forming apparatus of the present invention.

FIG. 4 is a waveform chart for explaining drive control of a counter electrode included in the image forming apparatus of the present invention.

FIG. 5 is an explanatory diagram for explaining a cleaning operation of a control electrode included in the image forming apparatus of the present invention.

FIG. 6 is a sectional view of a support of a recording paper suction mechanism provided in the image forming apparatus of the present invention.

FIG. 7 is a sectional view of a support of a recording paper suction mechanism provided in the image forming apparatus of the present invention.

FIG. 8 is a sectional view of a support of a recording paper suction mechanism provided in the image forming apparatus of the present invention.

FIG. 9 is a top view of a matrix control electrode.

FIG. 10 is a configuration diagram of a main part of the color image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming part 2 Toner supply part 3 Printing part 5 Recording paper 10 Paper feeder 11 Fixing part 21 Toner 22 Toner carrier 25 Counter electrode 25a Flat part 26 Control electrode 96 Chamber 93-1,93-2 Fans 94A to 94D Support Body 94-1 to 94-4 Inlet 104A to 104D Groove

Claims (5)

[Claims] 1. A toner carrier for carrying a toner, a counter electrode disposed opposite to the toner carrier to form an electric field between the toner carrier and the toner carrier under the action of the electric field A control electrode disposed on a flight trajectory of the toner flying toward the counter electrode, and a paper feeding unit for feeding a recording sheet onto a main surface of the counter electrode, wherein the control electrode is controlled based on an image signal. An image forming apparatus for forming an image on the recording paper by controlling a potential, wherein a support surface substantially coplanar with a main surface of the counter electrode and an air inlet opening to the support surface are formed. A support for supporting paper on the support surface; and suction means for sucking air through the suction port to suction the recording medium onto the support surface. Downstream of the recording paper sending direction An image forming apparatus having a plurality of grooves formed on a side thereof in parallel with the feeding direction. 2. The image forming apparatus according to claim 1, wherein a plurality of suction ports are formed in a recording paper sending direction or a direction perpendicular to the recording paper sending direction. 3. The image forming apparatus according to claim 1, wherein the groove is formed on a downstream side of the suction port in a recording paper sending direction. 4. The image forming apparatus according to claim 1, wherein the air inlet is formed so as to communicate with the groove. 5. The image forming apparatus according to claim 1, wherein a slope is provided on a wall surface on one end side of a groove positioned on a downstream side in a recording paper sending direction.