JP2002351218A - Powder transport device, developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder transport device which prevents leakage of a charged particle to the outside of the edge of a line-shape electrode by simple composition, does not cause poor transport and scatter of the charged particle to the outside of the transport device, and realizes stable and uniform powder transport, a developing device, and an image forming device. SOLUTION: Both end parts of a counter electrode substrate 60 vertical to the transport direction are bent toward the line-shape electrode 1 with an angle. The interval between the line-shape electrode 1 and the counter electrode 69 is arranged such that it gradually becomes narrow with a breadth 1 toward the end at the end part. At the end part of a transport electrode substrate 50, an action which pushes back the charged particle 7 to the central side of the line-shape electrode 1 where a parallel electric field is formed operates. Therefore, it is possible to prevent the occurrence of poor transport caused by the charged particle leaking to the range outside of the edge of the line-shape electrode 1 and by not receiving the action of the transport electric field.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder conveying device using a so-called electric field curtain, and is applied to, for example, a developing device of an electrophotographic image forming apparatus using a developer.

[0002]

2. Description of the Related Art Conventionally, charged particles are placed on a linear electrode group, and a time-varying voltage is sequentially applied to the electrode group to form a traveling wave electric field. Has been proposed as a "electric field curtain type powder conveying apparatus".

[0003] This "electric field curtain type powder conveying apparatus"
Since powder can be transported without relying on mechanical operation, there is no deterioration due to mechanical abrasion of the driving part, vibration during operation, etc. Become.

Application of this "electric field curtain type powder conveying apparatus" to an electrophotographic image forming apparatus is disclosed in Japanese Patent Publication No. 47-47811, Japanese Patent Laid-Open Nos. 58-22156, 59-181367 and 59-181367. It has been proposed in publications such as 63-12527.

In an electrophotographic image forming apparatus,
In the developing step of visualizing the electrostatic latent image on the latent image carrier with the charged particles (toner as a developer) by the charged particles,
When an electric field curtain type powder transfer device is used as the transfer means to transfer the charged particles from the toner container to the developing unit, there is no abrasion or vibration of the mechanical part, so there is no noise and long-term stable image formation. Operation can be maintained.

Here, a description will be given of a conventional powder conveying apparatus based on an electric field curtain system. FIGS. 7 to 9 show views of a transfer substrate in a general electric field curtain type powder transfer device.

[0007] 0.01 to 1.00 mm on the transfer board 57
A large number of linear electrodes 1 having a width of about 1 are fixed and arranged in a line at intervals of about 0.01 to 1 mm (these linear electrodes 1 are referred to as an electrode group). The space between the individual linear electrodes 1 is filled with an inter-electrode insulator 58 in order to prevent a short circuit and eliminate irregularities on the substrate surface. A voltage is sequentially supplied to each of the linear electrodes 1 to form a traveling wave electric field (moving electric field), and the charged particles are conveyed to the left in the drawing by the action of the electric field.

As shown in the figure, a power supply A81, a power supply B82, and a power supply C83 for generating a large number of alternating voltages (transport biases) having different phases are connected to the surface of the transport electrode substrate 50 in a periodic order as shown in FIG. The linear electrode 1 is provided, and the transport electrode substrate 50 generates an alternating electric field having a traveling waveform by applying a transport bias.

As shown in FIG. 10, for example, as shown in FIG. 10, the phases of the alternating voltages applied to the power supply A81, the power supply B82, and the power supply C83 are shifted from each other by 120 °, and the transfer bias V2 of the power supply B82 is changed to the transfer bias of the power supply A81. As the phase advances by 120 ° with respect to V1, the carrier bias V3 of the power source C83 becomes 12 phase shifted with respect to the carrier bias V2 of the power source B82.
It is adjusted to advance by 0 °.

That is, each power supply voltage is expressed as follows. V1 = Vmsinωt, V2 = Vmsin (ωt−2π / 3), V3 = Vmsin (ωt−4π / 3), where V1, V2, and V3 are power supply A81, power supply B82,
This is an alternating voltage (transport bias) applied to the power supply C83. Vm is the maximum value (Vmax) of each power supply voltage, and is usually the same value for each electric wire.

A power supply A81, a power supply B
82, by applying AC voltages of three or more phases having different phases from each other by the power source C83, for example, as shown in FIG.
As shown in FIG. 9, the power supply A81 has linear electrodes I2 and I2.
, I8, I11..., The power source B have linear electrodes I1, I1
, I7, I10, I13,...
0, I3, I6, I9, I12... When an AC voltage as a carrier bias having a phase difference is applied, a traveling wave AC electric field is generated in the direction of arrow F on the surface of the carrier electrode substrate 50.

The operation of the charged particles at this time is shown in FIG. 11 with the configuration of FIG. 7B showing the schematic configuration of FIG. 7A. When placed in an alternating electric field, the charged particles are attracted by the alternating electric field on the surface of the linear electrode 1 and start moving in the direction of the arrow in FIG.

By applying a carrier bias to the linear electrode 1, the charged particles on the carrier electrode substrate 50 are changed to a state shown in FIG.
(C) is electrostatically attracted to the linear electrode 1 having the strongest electric field indicated by the black circle and moves. Here, since the three-phase alternating current having a phase difference is applied, the peak of the electric field temporally forms a traveling wave, and therefore, FIG.
11 (c), the charged particles have the highest voltage of each phase, that is, the power source A81 in FIG.
The electrode moves forward by one electrode toward the electrode group of the linear electrode 1 connected to the power supply B82 in (b) and the power supply C83 in FIG. 11C, respectively.

In this way, the charged particles transition on the linear electrodes 1 of the transport electrode substrate 50 one after another and are transported.

The carrier bias may have a waveform such as a rectangular wave or a triangular wave as long as it forms a traveling wave due to a temporal change. A similar effect can be obtained even if the time changes in a form in which the time progresses.

The voltage applied to each electrode is selected in the range of several tens of volts to several kV depending on the thickness of the linear electrode 1 and the quality of the charged particles. Applied voltage (Peak-To-
The higher the Peak, the stronger the electrostatic force is generated and the better the transportability, but it is limited by the withstand voltage of the electrode and the insulator.

When the powder is conveyed by using the electric field curtain method, (1) since the conveyance is performed only by electric force, and there is no mechanical mechanism, the wear of the components and the load torque at the time of driving are reduced. Without long-term operation,
(2) Since the particles can be electrically controlled, the amount, speed, and direction of the particles can be easily controlled, and the response can be controlled quickly. (3) The particles themselves can be moved by direct movement. Therefore, there is an advantage that a mechanical load is not applied to the particles and the property of the particles is not deteriorated.

However, in the electric-field-curtain-type powder conveying apparatus composed only of the conveying electrode substrate 50, since it moves only by the electrostatic force, the conveying force is small, or the conveying can be carried out by the disconnection of the linear electrode. There were problems such as disappearance.

An inventor of the present invention has proposed an electric field curtain type powder conveying apparatus which solves these problems. As shown in FIGS. 7 and 8, the opposing electrode substrate 60 is provided with a gap in the transport electrode substrate 50,
By applying an alternating voltage independent of that applied to the linear electrode 1 to the opposing electrode 69 on the opposing electrode substrate 60 side to form an alternating electric field between the transport electrode substrate 50 and the opposing electrode substrate 60, The charged particles 7 fly between the transport electrode substrate 50 and the counter electrode substrate 60, and
To solve the above-mentioned problem by transporting the electric field by a traveling wave electric field formed by a voltage so that the potential distribution applied to the linear electrode 1 changes with time in a traveling wave shape having a constant traveling direction. Is possible, more efficient, and
Stable powder conveyance can be performed.

[0020]

However, in the case of the above-described prior art, the following problems have occurred.

In the electric curtain type powder conveying device,
The charged particles 7 move in the same cycle in accordance with the application of the traveling wave electric field to the linear electrode 1. However, the responsiveness to the traveling wave electric field actually varies depending on the charge amount and the mass of the charged particles 7, and therefore, the time lag varies from particle to particle.

For this reason, a particle that starts moving quickly (has a large charge or a small mass) may collide with a stationary particle that starts moving slowly (a small charge or a large mass). Due to this collision, the area a in FIG.
As shown in (1), the direction of motion of the particles is bent with respect to the direction of travel of the traveling wave electric field (in the figure, the direction is bent to the left).

Normally, since the linear electrodes 1 are all formed in a linear shape which is straight, even if the traveling direction is slightly bent near the center as shown in a region a in FIG. , The charged particles 7 are transported without any problem.

However, in particular, the transfer electrode substrate 50
At the end, due to the configuration, the linear electrode 1 is suddenly interrupted, so that when the traveling direction of the particles is bent due to the collision between the particles, as shown in a region b in FIG. The charged particles during transportation may move from the boundary between the side where the linear electrode 1 exists and the side where the linear electrode 1 does not exist to the side where the linear electrode 1 does not exist.

Then, the charged particles 7 are separated from the linear electrode 1, so that the transport electric field does not work. As a result,
As shown in a region c in FIG. 12, the user cannot move as it is. Therefore, when transported by this device,
The phenomenon that the charged particles 7 drips and spreads outside the end of the linear electrode 1 and the particles are deposited has occurred.

The charged particles 7 dripping outside the end of the linear electrode 1 are not transported again because the action of the transport electric field is almost eliminated, and stay there and continue to be accumulated. Therefore, as shown in a region d in FIG. As a result, the charged particles 7 stored in the shape of a mountain collapse and a large amount of agglomeration occurs.
There has been such a phenomenon that a transport failure occurs due to riding on the top, and a particle spills from an end of the apparatus and scatters to an unnecessary portion to contaminate the inside of the apparatus.

Further, since the charged particles are dropped from the outside of the linear electrode 1 and stopped from being conveyed, the amount of the charged particles conveyed near the end is reduced. This causes a difference in the amount of the particles to be transported, and a problem has occurred in that a uniform amount of the charged particles cannot be transported in the transport width direction (the direction perpendicular to the transport direction). Such a phenomenon becomes more remarkable as the transporting distance becomes longer. In an extreme case, the linear electrode 1 is located at the exit of the apparatus.
In some cases, the charged particles 7 were discharged only from the central portion of the.

In order to solve such a problem, as shown in JP-A-63-13071, a second transfer electrode group is provided at the end of the first linear electrode.
As shown in Japanese Patent Publication No. 13073, a configuration has been proposed in which a linear electrode end portion is configured to be angled forward, or both ends are vertically bent so that the linear electrode end is not formed in a planar shape. However, there is a drawback that the configuration of the electrodes and the transport control become complicated, resulting in an increase in cost.

The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to prevent the charged particles from dripping out of the end of the linear electrode by a simple structure and to convey the particles. An object of the present invention is to provide a powder transport device, a developing device, and an image forming device that realize stable and uniform powder transport without causing defects and scattering of charged particles to the outside of the transport device.

[0030]

In order to achieve the above object, in a powder conveying apparatus according to the present invention, a linear electrode group is arranged in parallel, and a time period in which the electrode group has a certain traveling direction is set. Electrode part that forms a traveling-wave electric field by applying a voltage that changes gradually, and a counter electrode that faces the carrier electrode part at an interval and forms an alternating electric field that causes charged particles to fly between the carrier electrode part and the carrier electrode part A powder transport device that transports the charged particles that have been fly by an alternating electric field by a traveling wave electric field, wherein the transport electrode portion and the transport electrode portion at an end of the counter electrode portion in a direction perpendicular to the charged particle transport direction. An end portion of the counter electrode portion in a direction perpendicular to the charged particle conveyance direction is made closer to the end with respect to the transfer electrode portion so as to narrow the opposing interval with the counter electrode portion toward the end. I do.

It is preferable that the width of the opposing electrode portion to which a voltage is applied in the direction perpendicular to the direction of transporting the charged particles is longer than the width of the transport electrode portion to which a voltage is applied in the direction perpendicular to the direction of transporting the charged particles. is there.

The width in which the transport electrode portion and the counter electrode portion in the direction perpendicular to the charged particle transport direction are opposed to each other in parallel is:
It is preferable that the width is wider than the use width in the direction perpendicular to the charged particle transport direction, and that the use width is included.

A developing device according to the present invention includes the above-described powder conveying device, and uses a developer as charged particles.

An image forming apparatus according to the present invention includes the developing device described above, and a latent image carrier on which an electrostatic latent image is visualized by using a developer of the developing device. The image of the developer is transferred from the image carrier to the sheet to form an image.

Preferably, the working width is a maximum forming width of the electrostatic latent image on the latent image carrier.

[0036]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) A first embodiment will be described with reference to FIGS. In the first embodiment according to the present invention, a counter electrode substrate 60 serving as a counter electrode portion facing a transfer electrode substrate 50 serving as a transfer electrode portion for applying a three-phase alternating current is provided with an interval. As shown in FIG. 1B, the end of the counter electrode substrate 60 in the direction perpendicular to the charged particle transport direction is connected to the transport electrode substrate 50.
, And are arranged so that the distance between them and the transfer electrode substrate 50 gradually decreases toward the end.

As a result, it is possible to prevent the charged particles 7 from dripping into the non-transport area outside the end of the linear electrode 1 and to carry out the powder transport more efficiently.

In the present embodiment, the same reference numerals are given to the components described in the above-mentioned prior art, and the description thereof will be omitted. Since the method of transporting the charged particles is the same, the description will be omitted.

As shown in the sectional view in the transport direction of FIG. 1B, a counter electrode substrate 60 having a counter electrode 69 is provided facing the transport electrode substrate 50 with a gap.

In the present embodiment, the linear electrode 1 composed of a comb-shaped linear electrode is formed of a conductive thin film by photolithography. Specifically, FIG.
In the same manner as shown in FIG. 3, an insulating film (SiC) and a conductive film (aluminum) are alternately formed on an insulating substrate (a glass substrate in this embodiment) by a vacuum film forming method, and the comb-like electrode portion is formed by etching. , A thin film electrode connected in three groups of A, B and C was prepared. At this time, the width of each linear electrode 1 is 1
00 μm, the electrode spacing is 50 μm, and the electrode films 51, 5
3, 55, and the thickness of the insulating films 52, 54, 56 between the electrode films 51, 53, 55 and the linear electrodes 1 were set to 10 μm and 15 μm, respectively, in consideration of the withstand voltage.

In this embodiment, the electrode films 51 and 5 are formed by using a multi-layer film forming technique, which is an advantage of the photolithography method, to have a layered structure of the electrode films.
In order to apply an alternating voltage to the linear electrode 1 from 3, 55,
An electrode was also formed at the end of the linear electrode 1 in the depth direction. That is, as shown in the cross-sectional view of FIG. 7, the connection electrode films 51, 53, and 55 are provided on the first, third, and fifth layers, and the short-circuit prevention insulating films 52, 54, and 56 are provided on the second, fourth, and sixth layers. The linear electrode 1 is formed on the seventh layer (outermost layer). The surface of the seventh layer is covered with a transport electrode insulating film 91.

For the electrode group A, the linear electrodes 1 of the first layer 51 and the seventh layer are provided, and for the electrode group B, the third layer 53 is provided.
And the linear electrode 1 of the seventh layer and the fifth layer 5 of the electrode group C.
By cutting out the insulating films 52, 54 and 56 so as to connect the linear electrodes 1 of the fifth and seventh layers, respectively, and embedding the connection electrodes, electrical connection becomes possible.

Finally, in order to reduce unevenness due to the parallel arrangement of the plurality of linear electrodes 1, an inter-electrode insulator 58 made of an insulating resin is filled and coated between the linear electrodes 1 and on the surface. And insulating the linear electrodes 1 adjacent to each other and from a conductive substance adhering to the surface of the transport electrode substrate 50.

A, B, C
To the power supply electrodes 75, 74, and 73 (connected to the first, third, and fifth layers, respectively) are power supplies A, B, and C (81, 82, and 8 respectively).
By applying the AC voltage with the phase shifted from 3),
A traveling wave AC electric field can be formed on the plurality of linear electrodes 1 of the transport electrode substrate 50.

Further, the counter electrode substrate 60 is
The counter electrode 69 is disposed at the center. A fourth power supply D84 is connected to the counter electrode 69, so that an AC voltage independent of the AC voltage applied to the linear electrode 1 can be applied.

In this embodiment, a sectional view perpendicular to the transport direction of the electric-field curtain type powder transport apparatus is shown in FIG.
(B). The opposite electrode substrate 60 which is a feature of the present invention has both ends perpendicular to the transport direction bent at an angle toward the linear electrode 1. Counter electrode substrate 6
The surface of the zero counter electrode 69 is covered with a counter electrode insulating film 92.

As described above, since both ends perpendicular to the transport direction of the counter electrode substrate 60 are bent at an angle, the interval between the linear electrode 1 and the counter electrode 69 has a width l at the end toward the end. Are gradually narrowed, and 30
The interval from 0 μm is 150 μm at the end. In the present embodiment, the width l of the end portion (bent portion) where the opposing electrode 69 is brought close is 10 mm for both ends.

At the same time as applying the AC voltage from the power supply D84 to the counter electrode 69, the power supply A81, the power supply B82, and the power supply C
When a three-phase alternating current having a phase difference is applied from 83 to the linear electrode 1, in addition to a uniform parallel alternating electric field between the transport electrode substrate 50 and the counter electrode substrate 60, the linear electrode 1 of the transport electrode substrate 50 is applied. A traveling wave AC electric field (traveling wave electric field) is formed in the vicinity. At this time, since the parallel alternating electric field and the traveling wave electric field have an orthogonal relationship, they do not cancel each other, and therefore, the charged particles are affected by both electric fields.

Therefore, the charged particles are transferred to the transport electrode substrate 5
While flying up and down in the direction perpendicular to the zero and the counter electrode substrate 60, furthermore, a force is applied horizontally along the transport electrode substrate 50 by the direction in which the traveling wave electric field works most strongly, that is, the electric field in the horizontal direction. That is, the charged particles receive a combined electric field of these two electric fields, and fly between the electrodes in an oblique or saw-toothed zigzag manner, as shown in FIG.
As shown in (c), it proceeds along the transport electrode substrate 50.

On the other hand, at the end of the transport electrode substrate 50,
Since the linear electrode 1 and the counter electrode 69 gradually approaching each other face each other at an angle, an electric field having an uneven distribution is formed by the voltage applied to the counter electrode.
Due to this uneven electric field, the charged particles 7 flying between the counter electrode 69 and the linear electrode 1 have a function of pushing the charged particles 7 back to the center of the linear electrode 1 where the parallel electric field is formed.

Thus, even if the charged particles 7 attempt to move to the electrode end side due to collision, they return to the center side during the reciprocating flight between the counter electrode 69 and the linear electrode 1, and It is possible to prevent the occurrence of defective transport due to leakage to a region outside one end and no longer being affected by the transport electric field.

In the present embodiment, the mechanism of preventing the charged particles from leaking due to the end portion of the counter electrode substrate 60 gradually approaching is considered to be as follows.

As shown in FIG. 2, the lines of electric force Q generated between the plate electrodes O and P having an inclination act concentrically around the point where the plate electrodes O and P intersect. Therefore, the charged particles 7 flying and reciprocating between the electrodes move along the lines of electric force Q. At this time, since a centrifugal force acts on the charged particles, the charged particles reach the electrode surface on the opposite side, which is slightly shifted to the side of the separated portion from the direction of the line of electric force Q in the direction of arrow f. Since an AC voltage is applied from the power supply, when the polarity of the applied voltage changes and an opposite electric field is formed between the electrodes, similarly, the charged particles move further to the separated portion side (the left side in the drawing). Each time a reciprocating motion is performed between the electrodes, the charged particles gradually advance from the side close to the electrodes to the side away from the electrodes, and move to a portion where the electrodes become parallel, a parallel electric field is formed, and no centrifugal force is generated.

The effect of the present embodiment was confirmed by actually transporting charged particles. As charged particles, diameter 10μ
m to −20−− by corona discharge.
The same three-phase alternating current is applied to the transport electrode substrate 50 using particles having a charge of 30 μC / mg, and the opposite electrode substrate 60
The effect of this embodiment was confirmed by comparing the state of conveyance of the charged particles 7 in the configuration of the present embodiment having a bent portion at the end and the conventional configuration of only the parallel portion.

Here, a transport electrode substrate 50 formed by photolithography with a transport distance of 30 cm and a width of the linear electrode 1 of 30 cm is used in common, a transparent resin substrate is used as the counter electrode substrate 60, and a transparent conductive film of ITO is used. (Indiu
m Tin Oxide) as a counter electrode 69 and a width 31
cm, and the gap between the substrates 50 and 60 was arranged to be 300 μm at the center. Thus, the width of the opposing electrode 69 is wider than that of the linear electrode 1.

Further, in the case of the present embodiment, as shown in FIG. 1B, the bending length is set so that the gap between both ends of the transfer electrode substrate 50 and the counter electrode substrate 60 is 150 μm at the end.
The one bent at 0 mm was fixed and arranged. At this time,
By using a transparent resin substrate and a transparent electrode film on the counter substrate side, in the present embodiment, observation can be made from the upper surface of the charged particles being conveyed.

The transport bias applied to the linear electrode 1 is V
A three-phase sine wave of m = 100 V and fm = 5 kHz is used as an AC voltage V4 of the power supply D84, Vpp = 2000V, f4
= 200 Hz rectangular wave was applied to the counter electrode 69 side in common with the example of the present embodiment and the conventional example.

The charged particles were continuously supplied to the entrance side of the transport electrode substrate 50 for a certain period of time, and the transport state of the charged particles in the apparatus was observed and compared. In addition, particles coming out of the transfer electrode substrate 50 placed on paper at the outlet (discharge side) were accumulated, and the state of the amount of particles discharged from the outlet was examined.

In the case of the conventional configuration, when the transfer is performed by applying the transfer bias, particles that cannot be transferred start to accumulate in the region outside both ends of the linear electrode 1 and increase with time. . As a result, the amount of particles discharged from the outlet (discharge side) of the transport electrode substrate 50 has a mountain-like distribution with a large amount at the center and a small amount at both ends. If the charged particles continue to be transported for a longer time, the charged particles continue to accumulate at both ends of the linear electrode 1, and the outside of the transport electrode substrate 50, that is,
In addition to overflowing the outside of the apparatus, the deposited charged particles are electrostatically agglomerated and collapsed toward the linear electrode 1 while forming a large mass, forming a new obstacle, and blocking the transport of the charged particles. A phenomenon that would occur.

On the other hand, in the case of the configuration of the present embodiment,
Since the charged particles scattered at both ends of the linear electrode 1 during transport are brought back to the center side of the linear electrode 1 by forming an unequal electric field by bringing the counter electrode 69 close to the linear electrode 1, Particles that could not be transported off the end of the electrode 1 could be eliminated. Therefore, the particles discharged from the outlet (discharge side) of the transfer substrate could have a substantially constant distribution except for very close to both ends. Furthermore, since no new obstacles are formed in the transport area of the linear electrode 1 and no particles overflow from the end of the apparatus, the apparatus is stable for a long time, and contamination inside the apparatus is reduced. Particle transfer could be performed without causing any problems.

As described above, the distance between the linear electrode and the counter electrode in the vertical direction perpendicular to the particle transport direction becomes gradually narrower toward the end from the end to the vertical direction perpendicular to the particle transport direction of the counter electrode. By bending the end of the linear electrode closer to the end by bending the end in the direction, it is possible to prevent charged particles from leaking to the non-transport area outside the end of the linear electrode, and to maintain more efficient particle transport. Becomes possible.

(Second Embodiment) FIGS. 3 to 6 show a second embodiment. The second embodiment is characterized in that a bent portion of the counter electrode substrate 60 is arranged outside the effective transfer area.

Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

FIG. 3 shows a second embodiment. Usually, a powder conveying device using the electric field curtain method is used when moving particles from one “particle storage place” to another “particle use place (apparatus)”. Therefore, the conveyance width is set according to the particle use location. Also in the present embodiment, a second device 95, which is a particle-using device, is disposed at the end of the transport discharge port of the powder transport device using the electric field curtain method.

As described in the first embodiment, the opposing electrode 69 is provided so as to oppose the linear electrode 1,
In an electric field curtain type powder conveying apparatus in which an alternating electric field is generated between the electrodes 1 and 69 to cause the charged particles 7 on the linear electrode 1 to fly between the electrodes 1 and 69, the powder is transferred in the direction perpendicular to the direction of conveyance of the counter electrode 69 (transport width direction) By bending the end to approach the linear electrode 1, it is possible to prevent the charged particle 7 from leaking to the end of the device.

However, on the linear electrode 1 facing the bent portion of the counter electrode 69, the charged particles 7
Is returned to the inner central portion, so that the end portion of the linear electrode 1 may be smaller than the transport amount at the central portion.

For this reason, when the transport amount of the charged particles 7 is particularly required to be uniform in the transport width direction, the charged particles 7 have a role of returning the charged particles 7 to the center outside the required effective transport area. It is necessary to arrange a bent part.

FIG. 4 is a diagram showing the relationship between the electric field curtain type powder conveying apparatus of the second embodiment and the conveying width. As described above, both ends of the opposite electrode substrate 60 are L102 and L102.
The width of a region parallel to the linear electrode 1 at the center is L100. On the exit side of the device,
A particle discharge port having a certain width is provided to supply the particles in a uniform amount.

That is, for the effective transport area L104, which is the width of using the particles, of the second device 95, which is a particle-using device disposed at the end of the transport discharge port, L104 <L100
Further, the effective transport area L104 is located inside the width L100 of the area where the central electrodes 1 and 69 are parallel to each other. In other words, the width L1
00 is wider than width 104, and width 100 includes width 104.

According to this relationship, in the effective transport region L104 to which particles are supplied in the second device 95, a parallel electric field is formed by the linear electrode 1 and the counter electrode 69 being parallel in this device, and a centrifugal force is generated. The second device 9 when supplied on the second device 95
5 The amount of particles near the end increases due to the addition of particles pushed back from the end of the linear electrode 1 or the particles at the end move further inward due to the influence of the uneven electric field. Thus, it is possible to prevent a change in the transport amount due to a decrease in the amount.

The effect of the second embodiment was confirmed by actually transporting charged particles. As in the first embodiment,
The counter electrode substrate 60 is provided with a certain gap with respect to the transport electrode substrate 50.

As in the first embodiment, as the charged particles, polyester particles having a diameter of 10 μm and having a charge of −20 to −30 μC / mg by corona discharge were used.

The same transport electrode substrate 5 as in the first embodiment
0, a glass substrate as the counter electrode substrate 60,
ITO (Indium Tin Ox) which is a transparent conductive film
ide) was used as the counter electrode 69, and the gap between the substrates 50 and 60 was fixed and arranged so as to be 300 μm at the center, so that the charged particles 7 could be observed as in the first embodiment.

A power source D84 is connected to the counter electrode substrate 60, and a superimposed alternating current (AC) is applied from the power source D84 so that a steady (DC) voltage having the same polarity as the charged particles is applied to the counter electrode 69 as V4b. is there.

The AC voltage V4b applied to the counter electrode 69
Is Vpp = 2000 V, f4 = 200 from the power supply D84.
It is obtained by superimposing a DC voltage of V = −100 V on a rectangular wave of Hz.

The charged particles 7 are supplied to the entrance of the transport electrode substrate 50, and the outlet (discharge side) of the transport electrode substrate 50 is provided.
Then, in place of the second device 95, particles coming out of a paper having a width of 280 mm corresponding to the effective transport area L104 were accumulated, and the distribution of the amount of discharged particles from the outlet was examined.

Here, in the present embodiment,
Similarly to the first embodiment, both ends of the counter electrode substrate 60 having a width of 31 cm are bent at a bending length of 10 mm to form the linear electrode 1.
The width L100 of a portion parallel to the above is 290 mm (the bent portion of the counter electrode 69 is arranged outside the effective transport area L104).
Was formed and fixed and arranged so that the gap facing each other was 150 μm at the end.

On the other hand, for comparison, the bending length was 20 m.
m, the width L100 'of the portion parallel to the linear electrode 1 is 270 mm (the effective transport area L
Configuration B, in which the bent portion of the opposing electrode 69 is disposed inside the inner side of 104, was similarly fixed and disposed.

The width of the linear electrode was set to 30 cm as in the first embodiment.

The transport amount was determined by measuring the amount of particles discharged per unit time and comparing the central portion of the transport area with the end position of the 280 mm wide paper.

In the case of the configuration A, which is an example of the second embodiment in which the bent portion of the counter electrode 69 is arranged outside the effective transfer area, the center of the transfer area and the position of the end of the 280 mm wide paper are determined. Were the same, and the transfer amount in the effective transfer area was uniform.

On the other hand, in the configuration B in which the bent portion of the counter electrode 69 is arranged inside the effective transport area, the transport amount at the end position of the 280 mm wide paper is smaller than that in the central area of the transport area. The reduction was 10%, and a uniform transport amount could not be obtained in the effective transport area.

As described above, in the second embodiment, by disposing the bent portion of the counter electrode 69 outside the effective transfer area, the transfer amount in the effective transfer area can be made uniform. As a result, it is possible to maintain a more uniform transport amount in the transport width direction than before.

Next, an electrophotographic image forming apparatus using the second embodiment will be described as an example.

FIG. 5 is a schematic sectional view of an electrophotographic apparatus as an image forming apparatus according to the second embodiment. In an electrophotographic apparatus, a visible image is formed by electrostatically attracting and developing a developer (toner) as a charged particle on an electrostatic latent image formed on an image carrier (photoconductor drum 215). . Here, in the developing device 219, since it is necessary to transport the charged particles from the hopper container (toner hopper 231) to the image carrier, the electric field curtain type powder according to the second embodiment is provided to the transport unit (toner transport unit 230). Built-in body transport device.

By using the developing device 219 using such an electric field curtain type powder conveying device, the developing portion and the toner container portion can be arranged apart from each other, and the toner provided at a further distant position can be arranged. Since the toner can be stably transported from the container portion 234 to the developing container portion 232, the size of the toner container portion 234 is not limited by the space around the image carrier, and the toner container portion 234 having a large capacity can be used.
Can be installed. As a result, an electrophotographic apparatus can be provided which achieves both the downsizing of the apparatus, low running cost, and easy maintenance by disposing the toner container section 234 at a position where replacement is easy.

Further, by using the electric field curtain type powder conveying device for the toner conveying section 230 of the developing device 219, the toner conveying can be easily changed greatly only by controlling the applied bias. That is, since the toner is rapidly conveyed by increasing the frequency of the three-phase alternating current, it is possible to control the conveyance amount according to the consumption amount.

At the end of the image forming operation, reverse conveyance can be performed by applying a three-phase alternating current (reverse traveling wave) having a reverse phase difference. By returning the toner in the transport section to the toner container section 234 side, even if the apparatus is not used for a long period of time, the toner does not agglomerate in the transport path, so that stable transport is always possible. There are advantages.

In the electrophotographic apparatus, since the toner is electrostatically attracted to the electrostatic latent image on the image carrier, a bent portion of the counter electrode 69 is disposed inside the conventional electric field curtain structure or the effective transport area. In the case of such a configuration, the amount of toner supplied in the conveyance width direction changes, particularly at the end portion, so that the amount of toner that can be attracted to the latent image changes. In such a case, for example, the density at both ends of the image decreases, the characters at the ends become thinner, and the image quality deteriorates.

For this reason, the electric field curtain type powder conveying device as the toner conveying section 230 is required to make the toner supply amount uniform within the image forming area which is the effective conveying area.

The principle of the electrophotographic apparatus shown in FIG. 5 is as follows. A charging unit 217, an exposure unit 220, and a developing unit 21 serving as a developing unit are arranged around the photosensitive drum 215, which is an image carrier, which rotates at a constant speed, from the upstream side.
9, a transfer roller 210 as a transfer unit, and a cleaning device 213 are provided.

The charging means 217 uses a contact charging device.
And a voltage is applied to the conductive roller to generate a discharge, thereby uniformly charging the surface of the photosensitive drum 215.

Next, exposure of the photosensitive drum 215 is performed by the exposure device 220. That is, when an image signal is given to the laser diode, the laser diode irradiates the polygon mirror with image light corresponding to the image signal. The polygon mirror is rotated at a high speed by a scanner motor, and the image light reflected by the polygon mirror selectively rotates the surface of the photosensitive drum 215, which rotates at a constant speed via an imaging lens and a reflection mirror, with a width of a maximum image forming width L204. To form an electrostatic latent image by lowering the potential on the photosensitive drum 215.

The developing device 219 will be described in detail later.
The developing sleeve 23 is located at a position facing the photosensitive drum 215.
6 is fixedly arranged at a minute interval (about 300 μm) with respect to the photosensitive drum 215, and a visible image is formed by electrostatically attaching toner 207 containing a magnetic material to the electrostatic latent image on the photosensitive drum 215. Form.

A transfer roller 210 is provided in the transfer section. The transfer roller 210 has a metal shaft wound around a medium-resistance foamed elastic body, and is arranged in contact with the photosensitive drum 215. The sheet (transfer material) 202 is conveyed from the paper feed unit to the contact portion between the transfer roller 210 and the photosensitive drum 215 at the timing when the toner image formed on the photosensitive drum 215 reaches the transfer unit by rotation. . At this time, a bias is applied to the transfer roller 210 at the same time, and the toner image on the photosensitive drum 215 is transferred to the sheet 202.

Here, since the transfer roller 210 is driven separately from the photosensitive drum 215, the sheet 202 sandwiched between the two is conveyed at a predetermined speed to the left in the figure at the same time as the transfer process is performed. Then, it is sent to the fixing device 225 which is the next step.

The fixing device 225 fixes the toner image formed on the sheet 202 by the transfer roller 210. As shown in FIG. 5, a fixing roller 226 for applying heat to the sheet 202 and a sheet And a pressure roller 227 for pressing against the fixing roller 226. Each of the rollers 226 and 227 is a hollow roller and has a heater inside, and is driven to rotate. It is configured to press.

Thus, the sheet 20 holding the toner image
The toner 2 is conveyed by the fixing roller 226 and the pressure roller 227 and is applied heat and pressure to fix the toner on the sheet 202.

The cleaning device 213 has a cleaning blade 216 disposed in a cleaning container 214. The transfer residual toner on the photosensitive drum 215 that has entered the cleaning container 214 is removed by the cleaning blade 21.
6 is completely removed from above the photosensitive drum 215 by mechanical rubbing.

Next, the developing device 219 in the electrophotographic apparatus having the above configuration will be described. In the developing device 219, the developing container part 232, the toner container part 234,
And the toner transport unit 230.

The toner container 234 is
1 and a supply unit 233, and the toner hopper 231 is filled with a black magnetic toner made of black magnetite which also serves as a polyester resin and a colorant. Further, the toner hopper 231 has a configuration detachable from the developing device 219, and a rotatable brush roller 239 for applying a charge to the toner and feeding the toner to the toner conveying section 230 is provided below the container. A plate-shaped scraper 240 which is in contact with the 239 is provided. The brush roller 239 is connected to a drive gear (not shown) of the main body, and rotates.

The developing container 232 includes a rotatable metal cylinder (developing sleeve) 236 having a magnet 237 fixed and arranged therein, and a developing sleeve 236 after the developing process.
The toner collecting device 238 collects and stores the toner. A developing power source (not shown) is connected to the developing sleeve 236, and a predetermined developing bias can be applied.

The developing container section 232 and the toner container section 234 are connected by a toner conveying section 230 which is an electric field curtain type powder conveying apparatus according to the second embodiment. When the image forming operation is started, the brush roller 239 below the toner container unit 234 is rotated, and the power supplies A to D (81 to 84) of the toner conveying unit 230 are operated.

In the toner container section 234, the brush roller 2
As the 39 rotates, the toner in the toner hopper 231 first comes into contact with and rubs against the brush roller 239 to be charged and adhere to the brush roller 239. When the brush roller 239 with the toner attached thereto rotates and rubs against the plate-shaped scraper 240, the toner is scattered by the mechanical impact at this time. By adjusting the position of the scraper 240, the charged toner is removed. Toner container section 234
The toner is sent to the lower toner transport unit 230.

FIG. 5 (b)
As shown in (c), a counter electrode in which a bent portion of the counter electrode 69 is disposed on the upper surface outside the width of the image forming area, which is an effective use area, as described in the second embodiment of the present invention. The transfer electrode substrate 50 is arranged on the lower surface of the substrate 60.

The charged toner supplied to the toner conveying section 230 is supplied to the electric power curtains A to D (81) by the electric field curtain type powder conveying apparatus according to the present embodiment provided in the toner conveying section 230.
84), the toner is horizontally conveyed to the developing container part 232 while flying up and down in the toner conveying part 230.

In the developing container section 232, when toner is supplied from the discharge port conveyed by the toner conveying section 230,
The toner in the developing container part 232 is attracted to the developing sleeve 236 by the magnetic field of the magnet 237 inside the developing sleeve 236. By the rotation of the developing sleeve 236, the toner coated on the developing sleeve 236 is
5 and is developed by applying a developing bias from a power supply connected to the developing sleeve 236 to develop an electrostatic latent image on the photosensitive drum 215.

Developing sleeve 236 not used for development
The upper toner is removed from above the developing sleeve 236 by the scraper of the toner collecting device 238 in contact with the developing sleeve 236, returns to the toner hopper 231 by gravity, passes through a collecting path below the developing device 219, and is used again. .

Here, the relationship of the width in each device will be described.
As shown in FIG. 6, the aforementioned “second utilizing particles”
The device 95 ”corresponds to the photosensitive drum 215 as a latent image carrier, and the“ effective use area ”is the maximum image forming width (latent image forming width) L204 on the photosensitive drum 215 and is output. Corresponding to the maximum image forming width of the image on the sheet 202.

In this relation, the width L200 of the area parallel to the linear electrode 1 at the center of the counter electrode 69 of the toner transport section 230 for transporting the toner, and the second device 95 disposed at the tip of the transport discharge port The maximum image forming width L204 of the photosensitive drum 215, which is the effective conveyance area, is
4 <L200, and the maximum image formation width L204 is located inside the width L200 of the region where the linear electrode 1 and the counter electrode 69 are parallel.
In the maximum image forming width of the photosensitive drum 215, it is possible to receive a toner supply having a uniform distribution, so that it is possible to output an image having a uniform density in the width direction.

The effect of the present embodiment is obtained by combining an electrophotographic apparatus incorporating a conventional electric field curtain type powder conveying apparatus with a counter electrode 69 outside the effective use area according to the second embodiment of the present invention. An actual halftone image (halftone image) and a character image were output and confirmed with an electrophotographic apparatus incorporating an electric field curtain type powder conveying apparatus characterized by having a bent portion.

In a conventional electrophotographic apparatus using the electric field curtain type powder conveying apparatus, in the case of a halftone image, the density of the image at both ends of the image is reduced in a vertical band shape, and the image quality is deteriorated. Was. Also, with respect to the character image, the characters at the portions corresponding to both ends of the image are thinned, and the output is difficult to read.

On the other hand, in the electrophotographic apparatus using the electric-field curtain type powder conveying apparatus according to the second embodiment of the present invention, the image density of the halftone image was uniform over the entire surface. Also, the character image was formed with a uniform thickness over the entire surface.

As described above, since the bent portion of the counter electrode 69 is arranged outside the effective use area, even when the electric field curtain type powder conveying apparatus is used as a developer conveying apparatus of an electrophotographic apparatus, Since the density and line width unevenness in the image area can be prevented, an output image excellent in quality can be obtained.

[0116]

As described above, according to the present invention, the charged particles are prevented from dripping out of the end of the linear electrode, and the transportation failure and the scattering of the particles due to the stagnation of the particles at the end are prevented. Good powder transportability can always be maintained.

[0117] Also, a second device disposed after the powder conveying device is provided.
The present invention realizes a uniform particle transport amount in the width direction of the particle using apparatus, and in particular, in an electrophotographic image forming apparatus, it is possible to maintain uniformity of density in an image area.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a powder conveying device according to a first embodiment.

FIG. 2 is an explanatory view showing the principle of a powder conveying system according to the present invention.

FIG. 3 is a schematic configuration diagram illustrating a powder conveying device according to a second embodiment.

FIG. 4 is an explanatory diagram illustrating a length relationship of a powder conveying device according to a second embodiment.

FIG. 5 is a schematic sectional view showing an image forming apparatus using a powder conveying device according to a second embodiment.

FIG. 6 is an explanatory diagram showing a length relationship of an image forming apparatus using a powder conveying device according to a second embodiment.

FIG. 7 is a schematic configuration diagram showing a conventional powder conveying device.

FIG. 8 is a schematic configuration diagram showing a conventional powder conveying device.

FIG. 9 is a schematic configuration diagram showing a linear electrode of a conventional powder conveying device.

FIG. 10 is a diagram showing a three-phase AC voltage.

FIG. 11 is an operation explanatory view showing the operation of the powder conveying device.

FIG. 12 is a schematic configuration diagram illustrating a problem of a conventional powder conveying device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 linear electrode 7 charged particle 50 transfer electrode substrate 51, 53, 55 connection electrode film 52, 54, 56 insulating film 57 transfer substrate 58 interelectrode insulator 60 counter electrode substrate 67 counter substrate 69 counter electrode 91 transfer electrode insulating film 92 Counter electrode insulating film

Claims (6)

[Claims] 1. A carrier electrode section in which linear electrode groups are arranged in parallel, and a traveling-wave electric field is formed by applying a time-varying voltage having a constant traveling direction to the electrode groups; A counter electrode portion facing at an interval and forming an alternating electric field that causes charged particles to fly between the carrier electrode portion and the carrier electrode portion. In the transfer device, the charged particles of the counter electrode portion are so formed that the distance between the transfer electrode portion and the counter electrode portion at the end of the counter electrode portion in the direction perpendicular to the transfer direction of the charged particles decreases toward the end. A powder conveying device, wherein an end portion in a direction perpendicular to a conveying direction is closer to an end of the conveying electrode portion. 2. The method according to claim 1, wherein a width of the opposing electrode portion to which a voltage is applied in a direction perpendicular to the charged particle transport direction is longer than a width of the transport electrode portion to which a voltage is applied in a direction perpendicular to the charged particle transport direction. The powder conveying device according to claim 1, wherein: 3. The width in which the transport electrode portion and the counter electrode portion in a direction perpendicular to the charged particle transport direction are opposed in parallel to each other,
The powder conveying apparatus according to claim 1, wherein the width is wider than a use width in a direction perpendicular to the charged particle conveyance direction, and the use width is included. 4. A developing device comprising the powder conveying device according to claim 1, wherein a developer is used as charged particles. 5. The developing device according to claim 4, further comprising: a latent image carrier on which an electrostatic latent image is visualized by using a developer of the developing device. Transfer the image of the developer to the sheet,
An image forming apparatus for forming an image. 6. The image forming apparatus according to claim 5, wherein the use width is a maximum formation width of the electrostatic latent image on the latent image carrier.