JPH10258540A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a developer from leaking when a matrix drive type control electrode section is used, to facilitate processing of the control electrode section, to obtain a good image by forming a uniform electric field, to prevent electric leakage such as electric discharge, to reduce the number of components, to downsize an apparatus, and lower the cost thereof. SOLUTION: A control electrode section is constituted of a first control electrode section 26f and a second control electrode section 26g. The control electrode is parallel to a tangent line of a surface of an opposing electrode 25 and is two-dimensionally spread by being in opposition to the opposing electrode 25. A toner carrier body 22 is disposed between the first control electrode section 26f and second control electrode section 26g. A toner flow can pass in a direction from the toner carrier body 22 to the opposing electrode 25. Flying of the toner 21 from the toner carrier body 22 to the opposing electrode 25 is controlled by means of a voltage supplied to the control electrode section.

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, a charged particle is caused to fly by an electric force by applying an electric field, and a plurality of passages arranged on a flight path are provided. 2. Description of the Related Art An image forming apparatus has been proposed in which an image is formed directly on a recording medium by changing a potential applied to a control electrode section including holes to cause charged particles to adhere to the recording medium.

In such an image forming apparatus, a single drive in which toner flying control is controlled by one electrode is generally used. However, in the case of such a single drive, it is necessary to dispose a potential switching means at each of the openings to control the flying of the toner. Therefore, a great number of potential switching means (normally transistors) are required. Was needed. In order to avoid such inconveniences, as disclosed in Japanese Patent Application Laid-Open No. 6-91918, column and row electrodes are arranged in a matrix and intersect and arranged in parallel. A matrix drive in which passage control is performed by a combination of potentials of row electrodes and column electrodes is used. In particular, in the case of the most common XY matrix as in the prior art, the number of transistors used is greatly reduced as compared with the case of the single drive.

As described above, in the case of a matrix drive, the number of transistors used is half that of a single drive, so that the cost can be reduced and the space for arranging the transistors can be reduced to reduce the size of the device. It becomes possible. Further, since the number of transistors to be turned on / off is reduced, there are various advantages such as a reduction in the current capacity of the power supply and a reduction in the cost of the power supply.

[0005]

However, in the case of a matrix drive, the following problems occur. In the case of a matrix, the toner flies only when a potential for causing the toner to fly (hereinafter referred to as an ON potential) is applied to both intersecting electrodes. In other cases, if at least one of the pair of electrodes provided around the opening is not at the ON potential, the toner will not fly. But,
Actually, even if one of the pair of potentials is an ON potential and the other is a potential that does not cause toner to fly (hereinafter referred to as an OFF potential), a small amount of toner flies to the counter electrode and becomes leakage toner. When the leaked toner is generated, fogging is caused and image deterioration is caused. When fogging occurs, even if a sufficient density is obtained in the formed dots, the fabric portion is not good, resulting in a blurred image with no contrast. Further, in the above case, halftone reproduction becomes insufficient, and in the case of a color image forming apparatus, color mixing occurs, and faithful color reproduction becomes difficult.

When the recording medium does not exist on the surface of the opposing electrode, the flying toner adheres to the surface of the opposing electrode even if a potential that does not cause the toner to fly is applied. When the recording medium is conveyed in this state, the recording medium is easily stained on the back. Alternatively, the toner attached to the opposing electrode changes the apparent potential of the opposing electrode, causing a problem such as insufficient toner flight control.

Further, when the leaked toner passes through the gate of the control electrode portion, the above-described problem is caused. However, when the leaked toner does not pass through the gate and adheres to the control electrode portion or the inside of the gate as it is, the control electrode portion has a problem. And the apparent potential of the control electrode unit with respect to the toner on the toner carrier changes due to the charge of the toner. Specifically, since the potential of the control electrode portion changes so as to be close to the potential at which the toner does not fly, flying of the toner becomes difficult. Further, even if a potential at which the toner flies is applied to the control electrode portion, the toner on the toner carrier does not feel a flying electric field and does not fly. Alternatively, clogging is caused by the toner adhering to the inside of the gate, and it is physically difficult to fly the toner. In this state, the dot formation operation is not performed, and printing failure occurs, resulting in image loss.

In order to avoid these problems, the following four methods are conceivable, but all of them newly induce the following problems. One is a method of applying a higher potential as an OFF potential. However, the potential difference from the potential at which the toner passes through the gate is further increased, and the breakdown voltage of the FET used is further increased. Also, if the OFF potential is sufficiently increased, the ON potential must be suppressed. In this case, sufficient toner density cannot be obtained due to insufficient toner flying, resulting in a blurred image without contrast. Therefore, the method of changing the potential is not appropriate because it is limited by the FET used. As a second method, there is a method of changing the opening diameter of the control electrode opening, for example, reducing the opening diameter on the counter electrode side. However, in this method, the effect of the electrode potential on the toner carrier side is less likely to appear, so that a higher potential is required as a potential to be used, and the same problem as described above is caused. In order to solve this problem while maintaining the withstand voltage of the FET, there is a method of bringing the control electrode portion closer to the sleeve.
Further, it is conceivable to reduce the interval between the matrix electrodes. These two methods not only require extremely high distance accuracy between the control electrode portion and the sleeve to be used, but also require a higher level of insulation between the electrodes of the control electrode portion, increasing the cost of the control electrode portion. A decrease in yield is inevitable. The fourth is control of the physical property value of the toner. Controlling the physical properties of the toner to be used (charge amount and toner layer thickness) can alleviate this to some extent, but it is very difficult to control the toner physical value of the charge quantity, and fluctuations in environmental conditions and the like are inevitable. It is actually difficult.

In addition, in the control electrode portion of the matrix drive described above, since the multi-layered electrodes are overlapped as described above, many steps are required, and furthermore, etching of a gate which becomes a toner passage hole, attachment of an electrode or Very high precision is required for drilling. For this reason, the yield of the control electrode part has deteriorated, and it has been difficult to reduce the cost.

From the above, it is very difficult to solve the problem with the conventional matrix electrode shape. Therefore, a method of disposing a belt-like carrier between matrix electrodes and supplying toner between the matrix electrodes is disclosed in Japanese Patent Application Laid-Open No. Hei 6-227022. However, since the belt-shaped carrier used is charged and the surface of the carrier can have a potential different from a desired potential, the surface potential of the toner becomes unstable. As a result, it is difficult to form a desired electric field between the carrier and the control electrode portion, that is, to form a flying electric field or a non-flying electric field of the toner and to properly switch between the two electric fields. Not enough. Further, since the carrier of the belt vibrates or floats with respect to the electrodes, the adhesion force of the toner carried on the carrier to the electrodes, for example, a mirror image force or a magnetic force, easily changes, and the flying amount of the toner is reduced. It is not uniform, causing image degradation. If the degree of this problem is worsened, the flight permission and the flight prevention cannot be sufficiently performed, and a printing failure occurs. Further, when the carrier floats up and comes into contact with or comes close to the control electrode portion, a discharge occurs with the control electrode portion, thereby causing destruction of the control circuit and the device. Further, the developer carried on the carrier comes into contact with the electrode group of the control electrode section, and the developer adheres. The electric charge of the adhered developer changes the potential of the electrode group, so that a good developer flying electric field cannot be obtained satisfactorily, which causes problems such as difficulty in flying control. In the worst case, the adhered developer adheres to the inside of the gate, causing clogging of the gate, which easily causes image dropout and poor printing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and when a control electrode portion of a matrix drive is used, leakage of a developer is prevented, and the processing of the control electrode portion is easy and uniform. An object of the present invention is to provide an image forming apparatus capable of forming a good image by forming an electric field, preventing electric leakage such as electric discharge, and reducing the number of components and the size and cost of the apparatus.

[0012]

According to a first aspect of the present invention, there is provided a carrier for supporting a developer, an opposing electrode arranged opposite to the carrier, and at least one or more of the above-mentioned members serving as a passage for the developer. At least one first electrode (group) having a gate is disposed between the carrier and the counter electrode, and the gate position is located on the side opposite to the counter electrode with respect to the outer peripheral surface on the counter electrode side of the carrier. The control electrode section in which the second electrode (group) is disposed so as to intersect with the first electrode (group), and the respective potentials of the first and second electrodes (group) are controlled and transported to the counter electrode. An image forming apparatus comprising: a first control unit and a second control unit for selectively controlling a flight to a recorded recording medium. The carrier is constituted by using a low-resistance member as a base material and at least electrically non-contact with the second electrode.

According to a second aspect of the present invention, the carrier has a medium-to-high resistance member as a base material, and has a static elimination member for eliminating charges on the surface of the carrier, or a power supply for supplying a potential to the static elimination member. It is characterized by the following.

According to a third aspect of the present invention, the second electrode (group) is movable in the direction of the carrier.

According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the third aspect, wherein the carrier has a means for attracting the carrier capable of generating at least a force directed toward the second electrode (group). It is characterized by.

According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the suction means is air suction and has an air inlet between the second electrodes (group). I do.

According to a sixth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the attraction means is a magnetic force generating means, and the carrier is formed of a magnetic material or a member mixed with a magnetic material. It is characterized by having.

According to a seventh aspect of the present invention, at least in the region where the first electrode (group) and the second electrode (group) are opposed to each other, the distance between the second electrode (group) and the second electrode (group) is uniform. It is characterized in that a body or a first electrode (group) is arranged.

The invention according to claim 8 is that, when the potential is sequentially applied to the second electrode (group) in a predetermined order, the second electrode (group) is connected to the end of the second electrode (group). ), A dummy electrode for applying at least the same potential as the potential applied during printing at the time of printing is provided.

According to a ninth aspect of the present invention, there is provided a magnetic field generating means for generating a magnetic field having an AC component at least in a region where the carrier and the electrode (group) face each other. The developer having the developer can be transported between the first electrode (group) and the second electrode (group).

In the first aspect of the present invention, since the carrier is sandwiched between the first and second electrodes (group), the electrode potential can be efficiently reflected on the electric field formed by the electrodes. That is, if there is a control electrode portion between the carrier and the counter electrode as in the related art, the developer may fly from the carrier when one of the electrodes is at the ON potential, and the leakage image may be generated. Although the agent was generated, the structure is such that the carrier is sandwiched between the first and second electrodes (group),
If there is no potential difference between the electrodes (groups) in the flight direction, the developer does not fly. Further, since only one layer of the first electrode (group) needs to be punched, the step of punching can be largely omitted. Further, since the carrier is made of a low-resistance member, the charge generated on the carrier can be easily neutralized, and the electric field is not disturbed by the charge. Further, since the carrier does not contact or electrically contact the second electrode (group), electric leakage between the second electrodes (group) generated via the carrier does not occur.

According to the second aspect of the present invention, since the resistance of the carrier is increased to some extent, the electric field formed by the first and second electrodes (groups) is smaller than when the resistance is low.
It is formed on the carrier and the first electrode (group). In addition, since the surface charge of the carrier is eliminated, there is no electric field formation failure due to the charge, and no discharge occurs even when the electrode (group) and the carrier come into contact.

In the third aspect of the present invention, since the second electrode (group) is movable, the second electrode (group) is always kept in contact with the carrier, or the distance between the two is always kept constant. It can be easily held.

According to the fourth aspect of the present invention, since the carrier has a carrier suction means capable of generating at least a force directed toward the second electrode (group), the second electrode (group) is attached to the carrier. On the other hand, it is easily possible to always maintain the contact state or to always keep the distance between them constant.
Further, since the carrier is attracted to the second electrode (group) and is always in contact with the carrier, the carried developer does not come into contact with the control electrode or the first electrode (group), and the developer adheres. And clogging of the gate does not occur.

According to the fifth aspect of the present invention, since the carrier is sucked to the second electrode (group) by air suction, suction of the carrier can be obtained with a relatively inexpensive structure, and further, the developer to be used can be obtained. A good developer layer can be maintained without having any influence on the state of the developer layer by the characteristics.

According to the sixth aspect of the present invention, since the carrier has magnetic properties and is attracted to the second electrode (group) by magnetic force, the second electrode is always kept in contact with the carrier or both are always in contact with the carrier. It is possible to keep the interval constant at a lower cost and more easily.

According to the seventh aspect of the present invention, since the distance between the first and second electrodes (groups) is made uniform, the electric field formed between both electrodes can be easily made uniform. Therefore, when the intervals are not uniform, the number of power supplies required can be reduced, and the circuit configuration can be simplified. In addition, since the carrier is equidistant with respect to the second electrode (group), it can be configured to make the image force of the developer uniform, and the entire region facing the second electrode (group) can be configured. Flight control is possible with a constant electric field.

According to the eighth aspect of the present invention, since an electrode having an OFF potential is disposed at an end of the second electrode (group),
It is possible to obtain uniform flying characteristics of the developer over the entire surface of the second electrode (group).

According to the ninth aspect of the present invention, a magnetic field having an AC component is generated between the first and second electrodes (group) and the developer is transported by the magnetic field. There is no need for a developer transport means with a typical configuration. Also,
Even when a steel toner carrier is configured, the toner carrier can be configured to be flat in a region facing the control electrode.

[0030]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a main part showing an embodiment of an image forming apparatus according to the present invention. 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 is appropriately set accordingly. do it.

As shown in FIG. 1, the image forming apparatus includes an image forming unit 1 having a toner supply unit 2 and a printing unit 3. The image forming unit 1 generates an image corresponding to an image signal,
This is to visualize the image on paper as a recording medium using toner as a developer. That is, the present image forming apparatus
The toner is caused to fly and adhere to the paper, and the flying of the toner is controlled based on an image signal to directly form an image on the paper.

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

A fixing unit 11 for fixing the toner image formed on the sheet 5 in the image forming unit 1 to the sheet 5 by heating and pressing is provided on the sheet output side of the sheet from the image forming unit 1. Is provided. The fixing unit 11 includes the heating roller 1
2, a heater 13, a pressure roller 14, a temperature sensor 15, and a temperature control circuit 80. The heating roller 12 is made of, for example, an aluminum tube having a thickness of 2 mm. Heater 13
Is composed of, for example, a halogen lamp and is built in the heating roller 12. The pressure roller 14 is made of, for example, a silicone resin. 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. Have been added. The temperature sensor 15 measures the temperature of the surface of the heating roller 12. The temperature control circuit 80 is controlled by the main control unit, controls ON / OFF of the heater 13 based on the measurement result of the temperature sensor 15, and keeps the temperature of the surface of the heating roller 12 at, for example, 150 ° C. Also,
The fixing unit 11 includes a paper discharge sensor (not shown) that detects that the paper 5 has been discharged. The heating roller 1
2. The materials of the heater 13, the pressure roller 14, and the like are not particularly limited. Further, the temperature of the surface of the heating roller 12 is not particularly limited. Further, the fixing unit 11
May be configured to fix the toner image by heating or pressing the paper 5.

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

The toner supply unit 2 of the image forming unit 1 includes a toner storage tank 2 in which a toner 21 as a developer is stored.
0, a toner carrier 22 as a belt-shaped carrier for carrying the toner 21, belt support members 22a and 22b for supporting and driving the belt by a driving unit (not shown), and a toner storage tank 20 provided therein. A doctor blade 23 that charges the toner 21 and regulates the thickness of the toner layer carried on the outer peripheral surface of the toner carrier 22. The doctor blade 23 is provided on the upstream side in the rotation direction of the toner carrier 22 so that the distance from the outer peripheral surface of the toner carrier 22 is, for example, 60 μm. The toner 21 is, for example, a non-magnetic toner having an average particle diameter of 6 μm, and is charged by the doctor blade 23 such that the charge amount is, for example, −4 μC / g to −5 μC / g.

In the inside of the toner storage tank 20, a peeling member 32a which comes into contact with the surface of the toner carrier 22 to peel off the toner layer on the surface of the toner carrier 22 and a toner carrier after the toner 21 layer is peeled off A roller-shaped neutralization brush 32c capable of contacting the surface of the surface 22 and performing static elimination on the surface;
A conductive roller 32b is disposed on the back surface of the toner carrier 22 so as to be in contact with the toner carrier 22 so as to be opposed to the neutralizing brush 32c. The conductive roller 32b is arranged opposite to the roller 32b. Having a supporting case member 32.

The distance between the doctor blade 23 and the toner carrier 22 is not particularly limited. Further, the average particle size and the charge amount of the toner 21 are not particularly limited.

The toner carrier 22 is driven by a driving device (not shown), and rotates in a direction indicated by an arrow A in FIG. Toner carrier 22
Is capable of carrying the toner 21 on its outer peripheral surface by an electrostatic force, a Van der Waals force, a cohesive force, or other inter-particle or inter-material force due to the charge of the toner 21. The rotation speed of the toner carrier 22 is not particularly limited.

The printing section 3 of the image forming section 1 has, for example, a thickness of 1
a high-voltage power supply 30 for supplying a high voltage to the counter electrode 25, a first control electrode unit 26f, and a second control electrode unit 26f.
A control electrode section 26 composed of a control electrode section 26g; a neutralizing brush 28; and a neutralizing power supply 1 for applying a neutralizing potential to the neutralizing brush 28
7. a charging brush 8 for charging the paper 5; a charging power supply 18 for applying a charging potential to the charging brush 8;
4, supporting members 16a for supporting the dielectric belt 24,
16b and a cleaner blade 19 are provided. The counter electrode 25 is provided such that the distance from the outer peripheral surface of the toner carrier 22 is, for example, 1.1 mm. The dielectric belt 24 is made of polyvinylidene fluoride (PVDF) and has a volume resistivity of 10 ¹⁰ Ω · cm and a thickness of 75 μm. The dielectric belt 24 is driven by a driving device (not shown), and the speed on its surface is, for example, 3 in the direction of the arrow in the figure.
Rotate at 0 mm / sec. A high voltage of, for example, 2.3 kV is applied to the counter electrode 25 by a high voltage power supply (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 unit 30 between the two.

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

When the toner 21 adheres to the surface of the dielectric belt 24 due to an unexpected situation such as a paper jam (paper jam), the cleaning blade 19 removes the toner 21 and removes the back surface of the paper. Is the toner 2
1 to prevent contamination. The counter electrode 2
The material of No. 5 is not particularly limited. Further, the distance between the counter electrode 25 and the toner carrier 22 is not particularly limited. Furthermore, the rotation speed of the counter electrode 25,
The applied voltage is not particularly limited.

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, An image memory for storing the image data and an image forming control unit for converting the image data obtained from the image processing unit into image data to be given to the control electrode unit 26 are provided.

FIG. 2 is a sectional view showing the vicinity of the control electrode section 26. The control electrode section 26 is two-dimensionally spread parallel to the tangential direction of the surface of the counter electrode 25 and opposed to the counter electrode 25, and can pass the toner flow from the toner carrier 22 toward the counter electrode 25. It has a structure. And
The electric field applied between the toner carrier 22 and the opposing electrode 25 changes according to the potential supplied to the control electrode unit 26, and the toner 21 from the toner carrier 22 to the opposing electrode 25 changes.
Is controlled.

FIG. 3 is a schematic configuration diagram of the first control electrode section 26f. The first control electrode portion 26f is provided so that the distance from the outer peripheral surface of the toner carrier 22 is, for example, 100 μm, and is fixed by a support member (not shown). As shown in FIG. 3, the first control electrode portion 26f includes an insulating substrate 26a, a high-voltage driver (not shown), and an independent strip-shaped conductor, that is, a strip-shaped electrode group 27b. The substrate 26a is made of, for example, a polyimide resin and has a thickness of 25 μm. Also, the substrate 26a
Is formed with a hole to be a gate 29 described later. The strip electrodes 27b are made of, for example, copper foil, are provided around the holes (gates), and are arranged according to a predetermined arrangement. The opening of each hole has a diameter of, for example, 160 μm, and serves as a passage for the toner 21 flying from the toner carrier 22 to the counter electrode 25. At the same time, the strip electrode 27b is arranged at a position corresponding to the gate so as to face the strip electrode group 27a. The first control electrode portion 26f and the toner carrier 22
Is not particularly limited. Each strip-shaped electrode 27b is provided with an opening having an opening diameter of 220 μm. Also, the size of the gate 29 and the substrate 26a
The material and thickness of the strip electrode 27b are not particularly limited.

FIG. 4 is a perspective view of the second control electrode portion 26g, and FIG. 5 is a configuration diagram of the control electrode portion viewed from the counter electrode side. The strip-shaped electrode 27a intersects the strip-shaped electrode 27b at a position corresponding to the gate 29.
Are arranged so as to be parallel to the longitudinal direction. The strip electrode 27a is formed on an insulating substrate 26b, and a dummy electrode 26e described later is formed on the insulating substrate 26b. The strip electrode 27a and the dummy electrode 26e are
6c. The insulating substrate 26b is supported by the illustrated support member. The insulating layer 26c is arranged to avoid discharge between the individual electrodes of the strip-shaped electrode 27a or between the individual electrodes and the toner carrier 22.

Each of the strip electrodes 27a and 27b is connected to the control power supply unit 3 via a power supply line and a high voltage driver (not shown).
1 electrically. As described above, the strip electrode 27a is covered with the insulating layer 26c. Similarly, the surface of the strip electrode 27b and the surface of the power supply line have a thickness of 30 μm.
m of the band-shaped electrode 27.
b, insulation between the power supply lines, and insulation between the toner carrier 22 and the counter electrode 25 are ensured. The material and thickness of the insulator layer are not particularly limited.

The strip electrodes 27a, 27b of the control electrode section 26
, A pulse corresponding to an image signal, that is, a voltage, is applied by a control power supply unit (control means) 31. That is, when the control power supply unit 31 allows the toner 21 carried by the toner carrier 22 to pass through the band-shaped electrode 27a in the direction of the counter electrode 25, for example, -200V is not passed,
For example, 150 V is applied. For example, 150 V and -200 V are applied to the strip electrode 27b.

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

Although the image forming apparatus is used as a printing unit of a printer as described above, it can be used as a printing unit of a facsimile or a digital copy. For example, an image forming operation of the present image forming apparatus when used as a printing unit of a digital copy will be described below with reference to FIG.

First, for example, when a document to be copied is placed on the image reading section and a copy start button (not shown) is operated, the main control section having received this input starts an image forming operation. That is, a document image is read by the image reading unit (step 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 converting the input image data into a control electrode unit control signal to be provided to the control electrode unit 26 ( Step S5).

When the image forming control unit obtains a predetermined amount of control electrode unit control signal (step S6; 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 S8). From the control power supply unit 31, the band-shaped electrodes 27a, 2
A voltage of 150 V or -200 V is appropriately applied to 7b (step S9). The aforementioned predetermined voltage is applied to the opposing electrode 25, the charging brush 8, and the discharging brush 28 to drive the dielectric belt 24 (Step S10). If the signal is not the desired control electrode section signal (step S6; NO), this flow is interrupted and an error is displayed (step S6).
7).

Next, the pickup roller 6 of the paper feeding device 10 is operated (step S11), and the recording paper 5 is taken out. The taken out recording paper 5 is sent out to the image forming unit 1 and is conveyed between the charging brush 8 and the support member 16a.
As described above, the counter electrode 25 and the support member 16a have a thickness of 2.3.
A high voltage of 1.2 kV is applied to the charging brush 8. Therefore, a negative charge is supplied to the surface of the sheet 5 conveyed between the charging brush 8 and the dielectric belt 24 due to a potential difference between the charging brush 8 and the support member 16a.
When a negative charge is supplied, the paper 5 is moved directly below the gate 29 by the movement of the dielectric belt 24 while being attracted to the dielectric belt 24 by the electrostatic force of the charge.
The electric charge on the surface of the dielectric belt 24 is attenuated with time until it reaches just below the gate 29, and the surface potential becomes 2 kV in consideration of the electric potential of the counter electrode 25.

The paper feed sensor detects whether or not the paper is in a normal paper feed state. If the paper feed is not performed normally (step S12; NO), this flow is interrupted and an error is displayed. (Step S13). If the paper is normally fed (step S12; YES), the image forming control unit sends the control electrode unit control signal to the control power supply unit 3.
Feed to 1. The supply of the control electrode unit control signal is performed at a timing corresponding to the supply of the paper 5 to the printing unit 3 by the charging brush 8 described above. The control power supply unit 31 controls the high voltage applied to each of the strip electrodes 27a and 27b of the control electrode unit 26 based on the control electrode unit control signal (Step S14). That is, a voltage of 150 V or -200 V is appropriately applied from the control power supply unit 31 to the predetermined strip electrodes 27a and 27b, and the electric field near the control electrode unit 26 is controlled according to image data. That is, when the toner 21 is caused to fly from the toner carrier 22 to the counter electrode 25 through the gate 29 of the control electrode unit 26, the voltage is -200V or 150V.
V is applied for 200 μsec per pixel, and toner 2
In the case where 1 does not pass, a potential of 150 V or -200 V is applied. As a result, the dielectric belt 24 on the surface of the counter electrode 25 moves by 30 mm / se toward the paper output side.
A toner image corresponding to the image signal is formed on the paper 5 moving at the speed c.

The paper 5 on which the toner image has been formed is the support member 1
The toner image is fixed on the paper 5 by the fixing unit 11 after being separated from the dielectric belt 24 and transported to the fixing unit 11 at the extreme rate of 6b. Paper 5 with toner image fixed
Is discharged onto a paper 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).

By the above image forming operation, a good image is formed on the paper 5. 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.

In the above description, the case where the potential applied to each band-shaped electrode 27 of the control electrode unit 26 for passing the toner 21 is 150 V or -200 V is taken as an example. There is no particular limitation as long as the desired flight control can be performed.

As described above, O applied to the strip electrode 27a
N and OFF voltages are set to -200 V and 150 V, and 150 V and -200 V are used for the strip electrode 27b, respectively. That is, the power supply used is -200V and 150
Only two types of V may be supplied from the same power source. In this case, only two power sources are required for controlling the flight of the toner 21 and the number of parts can be reduced, and the size and cost of the apparatus can be reduced. It becomes possible. However, depending on the toner 21 used and the configuration of the apparatus, the toner 21
When three or more potentials are required for flight control, a power supply may be used as appropriate. Similarly, the potential applied to the counter electrode 25, the potential applied to the charging brush 8, and the sheet 5 just below the gate 29.
Is not particularly limited as long as the desired flight control of the toner 21 can be performed.

The above is the outline of the image forming operation. Here, the image forming operation will be described more specifically. For example, when the passage of the toner 21 is given to the gate 29-n, the control electrode section is controlled by the control potential shown in FIG. Description will be made with reference to the control electrode shown in FIG. First, the strip electrode 27 provided with the gate 29-n
150 V and -200 V are applied to b-n and the strip-shaped electrode 27a-1 as potentials for causing the toner 21 to fly, respectively. In this state, an electric field is generated on the surface of the toner carrier 22 facing the gate 29-n due to a potential difference of 350 V between the belt-like potentials 27a and 27b, and the toner 2 existing in the area is formed.
1 flies towards the gate 29-n.

On the other hand, the following potential is applied to the strip electrodes corresponding to the gates 29-n + 1 to n + 3. That is, a potential of 150 V, which is applied for causing the toner 21 to fly, is applied to the strip electrodes 27b-n.
2 to 27a-4 are potentials 150 at which the toner 21 does not fly.
V is applied. Since there is no potential difference between the two electrodes and the electric field is not sufficiently formed, the toner 21 does not fly in the region facing the gate 29.

In addition to the above-mentioned band-shaped electrodes, for example, -200 V is applied to the band-shaped electrode 27b, and 150V is applied to the band-shaped electrode 27a.
Is applied. Although a potential difference is generated between the two electrodes, the electric field formed is in a direction in which a force is applied from the counter electrode 25 to the toner carrier 22.
At other than n, the toner 21 does not fly.

The ON potential is applied to the gate 29 other than the gate 29-n, for example, the gate 29-n + 1 to apply the toner 2
In the case of performing one flight, 150 V may be applied to the strip electrodes 27b-n according to the timing of the scan potential of the strip electrodes 27a. Thus, desired image data can be printed.

Next, the effects of the present invention and the present embodiment will be described. In an image forming apparatus of the type described in the prior art, a control electrode using a matrix drive having a configuration as shown in FIG. 8 is usually used. The behavior of the toner 21 carried on the surface of the toner carrier 22 under such control will be described with reference to FIG. In FIG. 9, the strip electrode 4
1a and 41b are arranged, and control by a matrix drive is performed. In this control, a state occurs in which the strip electrode 41a is ON and the strip electrode 41b is OFF. Strip electrode 41a
Is ON and the strip electrode 41b is OFF,
Although the toner 21 does not fly through the gate 29 due to the effect of the OFF potential of 1b, the toner 21 on the toner carrier 22 flies due to the potential applied to the band electrode 41a. It flies to the periphery or the periphery of the gate 29 or to the inside thereof to become the attached toner 21-a. The toner 21-b which adheres to the inside of the gate 29 exists in the adhered toner 21-a. In this state, the strip electrode 41a is OFF, and the strip electrode 41b is ON.
Because there is a moment when the gate 29 as shown in FIG.
The toner 21-b that has flown in or around it starts flying toward the counter electrode 25. When flying in this state, the toner 21-b that has reached the sheet 5 becomes fog toner, and becomes a blurred image with no contrast.

This phenomenon occurs as shown in FIG.
Is more remarkable when a control electrode of a type divided into right and left is used. The control electrode in FIG.
Is divided into strip electrodes 42b and 42d, and
1a is grouped into a strip electrode 42a and a strip electrode 42c, and the strip electrodes 42b and 42d are connected.
The control electrode unit 26 as shown in FIG. 11 has an advantage that the high-voltage driver 87 to be used can be reduced to about half as compared with the case of the XY matrix control electrode as in the above-mentioned prior art. In addition, if the number of high-voltage drivers is reduced by using a simple XY matrix as in the prior art, for example, an 8 × 320 matrix must be formed, resulting in a shape in which eight strip electrodes 42a are arranged. Therefore, the length (L in FIG. 11) of the paper 5 in the transport direction is increased.
When a control electrode such as 1 is used, the number of high-voltage drivers can be reduced without changing the length L at all. In the control electrode of FIG. 11, printing is performed by scanning the strip electrodes 42a and 42c at the ON potential. Therefore, when the above phenomenon occurs, a mirror ghost as shown in FIG. 12 occurs.

The above-mentioned ghost can be greatly improved when the opening diameter of the strip electrode 41 is formed as shown in FIG. In the shape as shown in FIG. 13, the diameter of the opening arranged on the toner carrier 22 side is larger than the diameter of the opening of the electrode arranged on the counter electrode 25 side.
The toner flies due to the ON potential on the side and the toner 2
Even if 1-a occurs, the amount of toner 21-b adhering to the inside of the gate 29 or in the vicinity of the gate 29 as shown in FIG. 9 is extremely reduced, and the degree of occurrence of fog toner and ghost as described above is greatly improved. Is done.

The above-mentioned problem is caused by the fact that the configuration of the control electrode section 26 used is, in particular, the opening diameter d1 of the strip electrode 41a on the toner carrier 22 side and the counter electrode 25
The opening diameter d2 of the band-shaped electrode 41b on the side is d1 = d2
Becomes more remarkable. However, when the shape of the control electrode section 26 is d1 <d2, the potential of the strip electrode 27b cannot be sensed by the toner 21 carried on the surface of the toner carrier 22, and the matrix control itself becomes difficult.
Alternatively, a case where the potential required for matrix control becomes extremely large may occur depending on the positions of the electrodes, the distance between the electrodes, and the like. In this case, the above-described problems such as an extremely high breakdown voltage of the FET are caused. Conversely, by setting the configuration of the control electrode to d1> d2 as described above, the necessary potential, that is, the toner 2
The potential difference between the potential at which the 1 does not fly and the potential at which the 1 does not fly becomes small, so that the withstand voltage of the FET to be used is reduced and the cost of the FET can be reduced. Since the number of FETs used is large, the cost reduction of the FET is a very effective cost reduction means for the entire device.

However, the above-described leakage toner and ghost cannot be completely avoided, and these problems cannot be avoided with the above-described configuration such as the control electrode. This is because the electric field formed by the potential applied to the electrodes does not reflect any change in the applied potential.

Since the present embodiment has the above configuration, the potential applied to the electrodes can be efficiently reflected in the electric field.
Further, flying toner 21-b such as toner 21-b generated when one electrode of the matrix electrode is turned on.
The potential problem of the prior art control electrode such as b does not occur, and all of the above problems can be avoided.
Therefore, problems such as leakage toner and ghost of the related art do not occur at all.

Further, in the control electrode section 26 as shown in FIG. 8 of the prior art, the electrodes 41a and 4a are provided on the front and back of the insulating substrate 26a.
Since the through hole, that is, the gate is further arranged by disposing 1b, the positioning of the through hole of the gate of the insulating substrate 26a and the gate of the two-layer electrode is very strict, and high-precision drilling is required. For this reason, the conventional control electrode has many disadvantages in that the number of steps is increased, the yield rate is reduced, and the production cost cannot be reduced. However, in the above embodiment, since the gate is arranged only on the strip-shaped electrode 41b, displacement of the through-hole between the electrodes basically does not occur, and no defective product due to displacement of the hole position between the electrodes does not occur at all. In addition, drilling can be largely omitted and simple drilling can be applied. Therefore, it is possible to easily achieve an improvement in the yield rate and a reduction in manufacturing cost.

In the above embodiment, the toner carrier 22
As a belt. When a belt is used as in the above-described embodiment, the toner 21 can be easily transported between the strip electrodes 27a and 27b, and the belt electrodes 27a and 27b can be easily transferred.
Since the area facing 27b can be constituted by a flat surface, the toner 2
1 can be uniformly formed over the entire surface of the strip electrodes 27a and 27b. If the carrying position of the toner 21 is not uniform with respect to the strip electrodes 27a and 27b, the toner 2
The image power of the electric charge of 1 on the strip electrodes 27a and 27b is not uniform. For this reason, there is a problem that the flying start electric field of the toner 21 and the obtained image density easily change and the flying control of the toner 21 is not good. For example, if the toner 21 is carried at a position relatively close to the electrode, the image force is strong and a large electric field is required as the electric field applied for flying. But,
When the toner 21 is carried at a position relatively far from the belt-shaped electrodes 27a and 27b, the above-mentioned image force is reduced, and the electric field required for flying the toner 21 can be reduced. Therefore, when the same electric field is applied to both of them, problems such as a change in flying density occur.

In order to avoid this inconvenience, it is necessary to increase the electric field applied to the region where the flight is insufficient. In this case, the number of potentials to be applied is increased, so that the number of power supplies to be used is increased. In addition, the withstand voltage of the FET which requires the means for switching the potential is increased, resulting in a simple increase in cost. In order to avoid an increase in the number of power supplies used, it is conceivable to make the electric field formed between the electrodes sufficiently large. When the electric field is sufficiently increased, the amount of the flying toner 21 is saturated and a constant flying of the toner 21 is obtained. However, in this case, it is unavoidable to increase the withstand voltage of the FET necessary for the above-mentioned potential switching means, which also leads to a simple increase in cost.

In the above-described embodiment, since the toner carrier 22 is formed in a belt shape, the toner 21 is held in a region opposed to the band electrodes 27a and 27b.
a and 27b can always be kept uniform. in addition,
Since the strip-shaped electrode 27a can always be formed at the same distance from the strip-shaped electrode 27b, the toner 21 can be carried so as to always have a uniform sensitivity to the electric field between the strip-shaped electrodes 27a and 27b, and good flying control of the toner 21 is always performed. can get. The material for the toner 21 belt is not particularly limited. However, a material which does not expand and contract as much as possible and whose resistance can be easily adjusted by mixing carbon black, an ionic conductive agent or the like, for example, PVD
Materials such as F and pets are suitable. In the above embodiment, the resistance value of the toner carrier 22 is set to 10 ⁹ Ωcm,
As a result, the electric charge induced on the surface of the toner carrier 22 can eliminate the charge by causing the charge removing brush 32c and the roller 32b to have the same potential. As in the above embodiment, 10
^For a low resistance of ⁵ to 10 < ⁸ > [Omega] cm, a certain amount of charge can be removed without separately providing a charge removing means. However, in order to neutralize the medium-to-high resistance member of 10 ⁹ to 10 ¹⁴ Ωcm, a neutralizing means such as the neutralizing brush 32c is required. For members having a resistance of about 10 ¹² to 10 ¹⁴ Ωcm, a power supply may be separately provided to provide a potential difference between them.

When the resistance value of the toner carrier 22 is even higher, the above-described static elimination power supply is indispensable. On the other hand, when the resistance value of the toner carrier 22 is reduced, even if the above-mentioned electric charge is induced on the surface of the toner carrier 22, it is quickly neutralized, so that the above-mentioned static elimination means becomes unnecessary. However, if the resistance value of the toner carrier 22 is too low, the potential of the band-shaped electrode 27a is shielded by the toner carrier 22, so that a desired electric field is not applied to the toner 21 carried on the toner carrier 22, and Matrix control becomes difficult. Further, for example, the belt-like electrode 27a is
Contact with the toner carrier 22 and the strip electrode 27a.
However, short-circuiting causes problems such as heat generation, circuit destruction, and electric discharge, so that the belt-shaped electrode 27a and the toner carrier 22 must not be in direct contact with each other. For example, a configuration in which the belt-shaped electrode 27a and the toner carrier 22 are not in contact with each other or a configuration in which the insulating layer 26c is disposed as in the above-described embodiment must be employed. Further, when the belt-shaped toner carrier 22 is loosened or bent, the distance from the control electrode is reduced, and a discharge may occur between the belt-shaped toner carrier 22 and the control electrode unit 26. In this case, the above problem occurs easily.

Conversely, when the resistance value of the toner carrier 22 is increased, the insulation between the toner carrier 22 and the belt-shaped electrode 27a becomes unnecessary.
2, the insulating layer 26c is not required, and the electrodes can be simplified and the cost can be reduced. However, the higher the resistance value of the toner carrier 22, the more the charge on the surface of the toner carrier 22 cannot be ignored, and the above-described static elimination means and the static elimination power supply are indispensable, and the potential difference required for the static elimination increases. ,
Various inconveniences such as power supply cost and increase in insulation of each component occur. Therefore, an appropriate value is generated in the range of the resistance value of the belt used as the toner carrier 22 as in the above embodiment. The resistance value is available belt characteristics and the toner 21 used characteristics and 10 but influenced by the state of the toner 21 layers ^{5 to 14} [Omega] cm to be used, 10 ⁹ [Omega] cm as described above in the above embodiments
Was suitable.

In the above embodiment, the toner carrier 2
Although a belt-shaped configuration was used as 2, the cylindrical member having the above-described resistance value may be formed when a very thin and hard material such as FRP can be used. In the case of a cylindrical member, there is no need for a mechanism for preventing skew and deviation as compared with a belt, and the distance to the strip-shaped electrode 27b is easily maintained at a constant level, thereby reducing the number of mechanical parts and reducing the size and cost of the apparatus. Becomes possible. In this case, the belt-like electrodes 27a are arranged as shown in FIG. 14, and more desirably, the belt-like electrodes 27a are arranged at an equal distance to the carrier as shown in FIG. Is preferably uniform.

In the above embodiment, the strip-shaped electrode 27a
, The number of electrodes is smaller than that of the strip-shaped electrodes 27b, and the potential scanning is further performed. If the strip electrodes 27a, 2
7b is not the above configuration. For example, there may be a case where the number of the strip electrodes 27a is larger than that of the strip electrodes 27b, contrary to the above embodiment. In this case, a large number of power supply lines for connecting the individual outputs of the potential switching circuit of the control power supply unit 31 and the individual electrodes of the strip-shaped electrode 27a must be arranged inside the toner carrier 22. Various inconveniences occur in terms of requiring a space and complicating production. However, since the electrode group having the smaller number of electrodes is arranged inside the toner carrier 22 as in the above embodiment, the configuration inside the toner carrier 22 becomes very simple, and conversely, the number of parts is reduced and It is possible to reduce the size and cost.

In the above embodiment, the dummy electrodes 26e are arranged as shown in FIG. As described above, a scan potential is applied to the strip electrode 27a. In this case, when the ON potential is applied to an arbitrary strip electrode 27a, the electrode adjacent to the electrode is always at the OFF potential. For example, as shown in FIG. 16, when there is no dummy electrode 26e, the electrode 27 disposed at the center of the insulating substrate 26b is used.
When an ON potential is applied to a-2 or 27a-3, the O
Both ends of the electrode to which the N potential is applied are always at the OFF potential. Electrodes arranged at one end, for example, 27a-1 and 2
When the ON potential is applied to 7a-4, the electrode 27a-2
The electrodes at both ends are not at the OFF potential as in 27a-3. Therefore, the electric field formation state is 27a-2 or 27a.
A case different from -3 is easily considered.

In this case, the electric field may be corrected by changing the potential applied to the electrodes 27a-1 and 27a-4. In this case, the number of necessary potentials increases, and the number of power supplies increases. Since a higher breakdown voltage is required as the switching means, an increase in the number of parts and an increase in the size and cost of the apparatus are inevitable.

However, in the above embodiment, as shown in FIG.
Since the dummy electrode 26e is arranged and the OFF potential is always applied, even if the ON potential is applied to 27a-1 or 27a-4, the ON potential is applied to 27a-2 or 27a-3. Similarly, both ends of 27a-1 and 27a-4 are always at the OFF potential. Therefore, 27a-2 and 27a-3
An electric field can be formed in the same manner as when an ON potential is applied to the first electrode. For this reason, the flying state of the toner 21 at each gate 29 is uniform, stable flying control of the toner 21 is possible, and good image formation is performed.

In the above embodiment, the electrodes 27a-2 and 27
Also in the case of a-3, there is no electrode to which the OFF potential is applied in the vicinity of the end, so that the electrodes 27a-2 and 27
It is preferable to dispose the dummy electrode 26e also at the end of a-3. Accordingly, a desirable form of the dummy electrode 26e is a rectangular electrode, and it is preferable that the electrode surrounds the periphery of the strip electrode 27a. In this case, at least during printing, it is necessary to apply the OFF potential as described above. For example, during non-printing, even when a potential that causes the toner 21 to form an electric field toward the toner carrier 22 is applied. Good.

The strip electrodes 27 of the control electrode section 26
“b” is disposed on the toner carrier 22 side of the insulating substrate 26a. If the toner 21 is the band electrode 2 of the control electrode unit 26
7b, the electric charge of the toner 21 has a potential with respect to the strip electrode 27b, and the potential is
It increases in proportion to the distance to b. Therefore, if the belt-like electrode 27b is arranged on the counter electrode side of the insulating substrate 26a and the toner 21 as described above adheres, the potential represented by the charge of the toner 21 is larger than that in the above-described embodiment. The value indicates a value, and specifically, acts to prevent the toner 21 from flying. If the attached toner 21 is the oppositely charged toner 21, the toner 21 acts in a direction to promote the flight of the toner 21, so that the flight control of the toner 21 may not be satisfactorily performed. In the above embodiment, the belt-like electrode 27b is arranged on the toner carrier 22 side, so that the above-described problem does not occur, and even if the toner 21 adheres, good flight control of the toner 21 and image formation can be performed. Become.

Further, the belt-like electrode 27a and the toner carrier 22
Is partially non-uniform, the toner 2
The surface potential of the toner 21 becomes non-uniform due to the potential of the electric charge of 1. In this case, there is a possibility that a trouble such as a minute discharge is partially generated between the belt-like electrode 27a and the toner carrier 22 or the carried toner 21. In this case, the distance between the toner carrier 22 and the belt-like electrode 27a is kept constant by the belt-like electrode 27a coming into contact with the toner carrier 22 or indirectly via an insulator. In this case, it is desirable that the surface potential of the toner 21 be kept uniform. In this case, as shown in FIG. 17, a pressing member 26h such as a spring or a leaf spring is disposed to attach the belt-like electrode 27a to the toner carrier 22. It may be configured to be pressed.

The toner carrier 22 is connected to the strip electrodes 27a, 27a.
It is very effective to always keep a constant position with respect to b for good printing for the following reasons. For example, in the case of the belt-shaped toner carrier 22 as in the above-described embodiment, the toner layer may come into contact with the control electrode unit 26 due to the slack of the belt or the like. In this case, the toner 21 adheres to the control electrode unit 26. Printing failure may be caused. Toner 21
Is adhered to the gate 29, the toner 21 is applied to the counter electrode 25 even if a potential that does not cause the toner 21 to fly is applied.
Will fly towards. Therefore, when the sheet 5 is present, image fogging is caused, and when the sheet 5 is not present, the counter electrode 25 is stained to cause back stain of the sheet 5. When the degree of the adhered toner 21 is deteriorated, clogging of the gate 29 is likely to occur, which easily causes image loss.

Further, when the resistance value of the toner carrier 22 is low, when it comes into contact with or comes close to the control electrode section 26, a discharge is generated between the control electrode section 26 and the control power supply 31 is destroyed. 26 or the toner carrier 22 is likely to be broken or damaged. In the worst case, the entire apparatus and other devices connected to the image forming apparatus may be destroyed or the user may receive an electric shock. Further, when the toner carrier 22 contacts or approaches the control electrode unit 26, the toner 21 contacts and adheres to the control electrode unit 26. The adhering toner 21 cannot change the apparent potential of the control electrode unit 26 due to its own electric charge to form a good flying electric field of the toner 21. Specifically, the electric field changes so that the toner 21 does not fly. As a result, good flight of the toner 21 cannot be obtained, which causes image deterioration. When the toner 21 adheres to the inside of the gate, the gate 29 is clogged, and the image is easily lost.

In order to avoid these problems, it is preferable to keep the toner carrier 22 at a certain distance from the strip electrode 27a or the insulating layer 26c. Desirably, it should be maintained in a state of being in contact with the strip electrode 27a or the insulating layer 26c.
As described above, it is preferable to have means for bringing the toner carrier 22 into contact with the strip electrode 27a or the insulating layer 26c.

In addition, as a method for pressing the toner carrier 22 against the belt-like electrode 27a as described above, for example, a configuration as shown in FIG. 18 or FIG. 19 may be employed. FIG. 18 shows a belt-shaped toner carrier 22 that has been
7a is sucked. As shown in FIG. 18, an intake port 94 for sucking air is disposed on the insulating substrate 26b.
Above the intake port 94, a pressure reducing means (not shown) is provided.
Due to the reduced pressure inside the intake port 94, the toner carrier 22 is sucked into the insulating layer 26c. Since the toner carrier 22 is driven in this state, the toner carrier 22 moves while always in contact with the insulating layer 26c. Therefore, the distance between the toner carrier 22 and the strip electrode 27a is always kept constant,
The above problems can always be avoided. The intake port 94 and the decompression means are not particularly limited.

FIG. 19 is an explanatory diagram for explaining a case where a magnetic field generating means is arranged as a suction means for sucking the toner carrier 22. In FIG. 19, a toner carrier 22a composed of a belt member mixed with a commercially available magnetic powder is arranged.
Further, a magnet 43 supported in contact or non-contact with the insulating substrate 26b is arranged. The magnet 43 attracts the toner carrier 22a by the magnetic force of the magnet 43 and the toner carrier 22a, and the toner carrier 22a is separated from the insulating layer 26c.
Can be brought into contact with the object. In the case of FIG. 19, the suction port 94 is not required in the insulating substrate 26b as compared with the case where the toner carrier 22 is suctioned by air as shown in FIG. It becomes unnecessary and the number of parts can be reduced, and the size and cost of the device can be reduced.

Further, with respect to the toner carrier 22a,
When it is difficult to control a good resistance value while maintaining magnetism, a non-magnetic toner carrier 22 is provided and
Is a magnetic toner. By disposing the magnet 43 and attracting the magnetic toner 21 by magnetic force, it is possible to indirectly attract the carrier. In this case, since the resistance value of the toner carrier 22 can be controlled independently, the cost of the toner carrier 22 can be reduced.

However, when the toner 21 is a magnetic toner, in the embodiment of FIG.
In some cases, a state of one layer cannot be obtained. In this case, the form and the magnetic field strength of the magnet 43 may be appropriately changed and adjusted so as to obtain a desired 21 toner layer. However, when it is difficult to adjust the magnet 43, air suction as shown in FIG. 18 is preferable.

It is also very effective that the magnet 43 is configured to generate an AC magnetic field so that the magnetic toner 21 is conveyed by the AC magnetic field. In this case, it is not necessary to form the toner carrier 22 in a belt or sleeve shape as in the above embodiment. Even when the toner carrier 22 is made of a steel body, the toner carrier 22 can be configured to be flat in a region facing the control electrode. Therefore, uniform toner flight can be realized over the entire surface of the control electrode unit 26, and desired toner flight control can be performed, and a good image forming operation can be obtained. Further, while the belt-like electrodes 27a and 27b are very narrow, the toner 21
Can be conveyed, so that the number of driving parts can be greatly reduced as compared with the case of forming a belt or a sleeve, and the number of parts can be reduced and the size and cost of the apparatus can be reduced. Means for generating an alternating magnetic field may be based on a well-known mag roller or the like,
There is no particular limitation.

In the above 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, the image forming units 1a and 1 each include a plurality of toner supply units and printing units.
A color image forming apparatus using color toners, for example, yellow, magenta, cyan, and black as shown in FIG. 20, may be formed in each of the toner supply units by arranging b, 1c, and 1d. In FIG. 20, image forming units 1a, 1b, 1c, and 1d according to the present invention are arranged corresponding to yellow, magenta, cyan, and black, respectively, and a color image is formed based on color image data. . Other components may have the same configuration as in FIG.
In the case of a color image forming apparatus, if the above-mentioned problem occurs, the desired amount of toner does not fly, so that the above dot diameter and density cannot be obtained. This causes a new problem that appropriate color reproduction cannot be obtained. However, according to the present invention, since the above-mentioned problems do not occur at all, desired color reproduction and good color image formation can be obtained.

In particular, when the leakage toner is generated, particularly when the surface of the paper 5 is developed with another color toner 21 before the leakage toner reaches the paper 5, color mixture occurs. In some cases, desired image reproduction cannot be obtained and good image formation is hindered. However, in the above-described embodiment, all of these problems are avoided.

In this embodiment, the case where the developer is a toner has been described as an example, but the developer may be an ink or the like. Further, the configuration of the toner supply unit 2 is
It is also possible to adopt a configuration to which an ion flow method is applied. That is, the image forming unit may be configured to include an ion source such as a corona charger. In this case, the same operation and effect as described above can be obtained.
In the present embodiment, the case where the developer is toner is described as an example, but the developer may be ink or the like. The image forming apparatus according to the present invention can be suitably applied to, for example, a printing unit of a digital copying machine and a facsimile machine, a digital printer, a plotter, and the like.

[0093]

According to the first aspect of the present invention, since the carrier is sandwiched between the electrodes (groups), the electrode potential can be efficiently reflected on the electric field formed by the electrodes, and when one of the electrodes has the ON potential. Since there is no flying toner generated, no toner leakage occurs at all, and good flying control of toner can be easily realized. Furthermore, since only one layer of the first electrode (group) needs to be drilled, the drilling process can be largely omitted, and the non-defective rate is greatly improved, making it possible to easily reduce the cost of the control electrode. Become. Further, since the carrier is made of a low-resistance member, charges generated on the carrier can be easily neutralized, and good flight control can always be performed. Further, since the carrier does not contact or electrically contact the second electrode (group), electric leakage between the second electrodes (group) generated through the carrier does not occur, and Therefore, it is not necessary to increase the power supply capacity as a countermeasure against the leak, and it is possible to reduce the number of parts and to reduce the size and cost of the apparatus.

According to the second aspect of the present invention, since the resistance of the carrier is increased to some extent, the electric field formed by the first and second electrodes (group) can be used efficiently. Further, since the surface charge of the carrier is eliminated, an electric field is not formed due to the electric charge, and a good image can be formed. Further, even when the electrode (group) and the carrier come into contact with each other, no discharge occurs and the above-described problem does not occur.

According to the third aspect of the present invention, the second electrode (group)
Is movable, it is possible to easily maintain the second electrode (group) in a constant contact state with the carrier, or to always keep the distance between the two electrodes constant, thereby achieving good toner flying. Control can be maintained.

According to the invention of claim 4, the second electrode (group)
Can be easily maintained in a contact state with the carrier, or the distance between the two can be always kept constant, so that the toner flying always constant in the region facing the second electrode (group). Characteristics can be obtained, and a uniform and good image forming operation can be obtained over the entire area. Further, since the carrier is attracted to the second electrode (group) and is always in contact with the carrier, the carried developer does not come into contact with the control electrode or the first electrode (group). Does not cause gate clogging.

According to the fifth aspect of the present invention, since the carrier is suctioned to the second electrode (group) by air suction, suction of the carrier can be obtained with a relatively inexpensive structure, and the characteristics of the toner used. Has no effect on the state of the toner layer,
The desired image forming operation can be realized by maintaining a good toner layer.

According to the sixth aspect of the present invention, since the carrier has magnetic properties and is attracted to the second electrode (group) by magnetic force, the second electrode is always kept in contact with the carrier or both are always in contact with the carrier. Can be maintained more inexpensively and easily.

According to the seventh aspect of the present invention, since the interval between the first and second electrodes (groups) is made uniform, the electric field formed between the two electrodes can be easily made uniform. When the intervals are not uniform, the number of power supplies required can be reduced, and the circuit configuration can be simplified. In addition, the carrier is a second electrode (group)
, It is possible to make the mirror image power of the developer uniform so that flight control can be performed with a constant electric field over the entire area facing the second electrode (group).

According to the invention of claim 8, the second electrode (group)
Since the electrode having the OFF potential is disposed at the end of the second electrode, uniform toner flying characteristics can be obtained over the entire surface of the second electrode (group), and no control for correcting the electric field formation at the end is required. As a result, a uniform electric field can be easily formed.

According to the ninth aspect of the present invention, a magnetic field having an AC component is generated between the first and second electrodes (groups), and the toner is transported by the magnetic field. Therefore, the toner carrier is constituted by a belt. This eliminates the need for a complicated driving means for driving the belt, thereby reducing the number of parts and reducing the size and cost of the apparatus. Further, even if a steel toner carrier is formed, the toner carrier can be formed flat in a region facing the control electrode, so that good toner flight control can be performed over the entire control electrode, and a good image forming operation can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part showing an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view near a control electrode unit of the image forming apparatus.

FIG. 3 is a schematic configuration diagram of a first control electrode unit 26f.

FIG. 4 is a perspective view of a second control electrode unit 26g.

FIG. 5 is a configuration diagram of a control electrode unit viewed from a counter electrode side.

FIG. 6 is a flowchart illustrating an image forming operation performed by the image forming apparatus.

FIG. 7 is a timing chart showing potential control of a control electrode unit.

FIG. 8 is a configuration diagram showing control electrodes by a normal matrix drive.

FIG. 9 is an explanatory diagram showing toner flying control by a normal control electrode.

FIG. 10 is an explanatory diagram showing toner flying control by a normal control electrode.

FIG. 11 is a configuration diagram showing another control electrode by a normal matrix drive.

FIG. 12 is an explanatory diagram illustrating an example of a mirror ghost.

FIG. 13 is an explanatory diagram showing toner flying control of another control electrode by a normal matrix drive.

FIG. 14 is an explanatory view illustrating another embodiment of the control electrode according to the present invention.

FIG. 15 is an explanatory view illustrating still another embodiment of the control electrode according to the present invention.

FIG. 16 is an explanatory diagram showing a control electrode without a dummy electrode.

FIG. 17 is an explanatory diagram illustrating a structure in which a control electrode is pressed against a toner carrier by a pressing member.

FIG. 18 is an explanatory diagram illustrating a carrier adsorbing means according to the present invention.

FIG. 19 is an explanatory view illustrating another adsorption means of the carrier according to the present invention.

FIG. 20 is a schematic configuration diagram illustrating an outline of a color image forming apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming part 2 Toner supply part 3 Printing part 21 Toner 22 Toner carrier 25 Counter electrode 26f First control electrode part 26g Second control electrode part 27a Second strip electrode 27b First strip electrode 29 Gate

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 25, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 4

FIG. 2

FIG. 3

FIG. 5

FIG. 8

FIG. 9

FIG. 6

FIG. 10

FIG.

FIG. 7

FIG. 11

FIG. 13

FIG. 14

FIG.

FIG. 16

FIG.

FIG.

FIG.

FIG.

Claims (9)

[Claims] 1. A carrier for supporting a developer, an opposing electrode disposed opposite to the carrier, and at least one first electrode having at least one gate serving as a passage portion of the developer. (Group) is disposed between the carrier and the counter electrode, and intersects the first electrode (group) at the gate position on the side opposite to the counter electrode with respect to the outer peripheral surface on the counter electrode side of the carrier. A control electrode section on which a second electrode (group) is arranged; and an electric potential of each of the first and second electrodes (group) are controlled to selectively fly the recording medium conveyed to the counter electrode. A first control unit and a second control unit for controlling, wherein the carrier is configured with a low resistance member as a base material and at least electrically non-contact with the second electrode. Characteristic image forming apparatus. A first electrode (group) having a carrier for supporting the developer, a counter electrode disposed opposite to the carrier, and at least one gate serving as a passage portion of the developer. A second electrode is disposed in parallel between the carrier and the counter electrode, and intersects the first electrode (group) at the gate position on the side opposite to the counter electrode with respect to the outer peripheral surface on the counter electrode side of the carrier. A control electrode unit having a plurality of (groups) disposed therein, and a control electrode unit configured to control respective electric potentials of the first and second electrodes (groups) to selectively control a flight to a recording medium conveyed to the counter electrode. The carrier comprises a medium-to-high resistance member as a base material, and supplies a charge to the charge removing member or a charge removing member for removing charge from the surface of the support, and a potential to the charge removing member. An image forming apparatus comprising a power supply. 3. A first electrode (group) having a carrier for carrying a developer, a counter electrode arranged opposite to the carrier, and at least one gate serving as a passage portion for the developer. A second electrode is disposed in parallel between the carrier and the counter electrode, and intersects the first electrode (group) at the gate position on the side opposite to the counter electrode with respect to the outer peripheral surface on the counter electrode side of the carrier. A control electrode unit having a plurality of (groups) disposed therein, and a control electrode unit configured to control respective electric potentials of the first and second electrodes (groups) to selectively control a flight to a recording medium conveyed to the counter electrode. An image forming apparatus comprising: one control means and a second control means, wherein the second electrode (group) is movable in the direction of the carrier. 4. The image forming apparatus according to claim 3, wherein said supply means includes a carrier suction means capable of generating a force toward said second electrode (group) toward said carrier. . 5. An image forming apparatus according to claim 4, wherein said suction means is air suction and has an air inlet between said second electrodes (group). 6. The image forming apparatus according to claim 4, wherein said attracting means is a magnetic force generating means, and said carrier is formed of a magnetic material or a member mixed with a magnetic material. 7. A first electrode (group) having a carrier for carrying a developer, a counter electrode arranged opposite to the carrier, and at least one gate serving as a passage portion for the developer. A second electrode is disposed in parallel between the carrier and the counter electrode, and intersects the first electrode (group) at the gate position on the side opposite to the counter electrode with respect to the outer peripheral surface on the counter electrode side of the carrier. A control electrode unit having a plurality of (groups) disposed therein, and a control electrode unit configured to control respective electric potentials of the first and second electrodes (groups) to selectively control a flight to a recording medium conveyed to the counter electrode. A control means and a second control means, at least in a region where the first electrode (group) and the second electrode (group) face each other, so that the distance between the second electrode (group) is uniform. An image forming apparatus, wherein the carrier or the first electrode (group) is disposed on the image forming apparatus. 8. A first electrode (group) having a carrier for supporting a developer, a counter electrode disposed opposite to the carrier, and at least one gate serving as a passage portion of the developer. A second electrode is disposed in parallel between the carrier and the counter electrode, and intersects the first electrode (group) at the gate position on the side opposite to the counter electrode with respect to the outer peripheral surface on the counter electrode side of the carrier. And a control electrode unit having a plurality of (groups) arranged thereon, and a control electrode for controlling the individual potentials of the first and second electrodes (groups) to selectively control the flight to the recording medium conveyed to the counter electrode. One control means and a second control means, and when a potential is sequentially applied to the second electrode (group) in a predetermined order, the second electrode (group) is connected to an end of the second electrode (group). It is necessary to arrange a dummy electrode that applies at least the same potential as that applied to the electrode (group) during printing. An image forming apparatus symptoms. 9. A first electrode (group) having a carrier for carrying a developer, a counter electrode arranged opposite to the carrier, and at least one gate serving as a passage portion for the developer. A second electrode is disposed in parallel between the carrier and the counter electrode, and intersects the first electrode (group) at the gate position on the side opposite to the counter electrode with respect to the outer peripheral surface on the counter electrode side of the carrier. A control electrode unit having a plurality of (groups) disposed therein, and a control electrode unit configured to control respective electric potentials of the first and second electrodes (groups) to selectively control a flight to a recording medium conveyed to the counter electrode. A magnetic field generating means for generating a magnetic field having an AC component at least in a region where the carrier and the electrode (group) face each other, and a magnetic field having the AC component The first and second electrodes (group) and the second electrode ( An image forming apparatus characterized in that it is fed between the).