JP4724525B2 - Toner conveying device and developing device having the same - Google Patents

Description

  The present invention relates to a toner conveying device, a developing device having the toner conveying device, and an image forming apparatus having the toner conveying device.

2. Description of the Related Art Conventionally, there has been known a developing device configured to perform development by supplying a developer onto a latent image carrier without directly contacting the developer on the developer carrier with the latent image carrier.
As an example, there is a conventional technique in which toner is supplied onto a latent image carrier by a toner conveying member.
The toner conveying member is arranged to face the latent image carrier, and a plurality of electrodes are arranged on the surface thereof at a predetermined pitch.
An n-phase AC voltage is applied to this electrode to generate a traveling wave electric field that conveys the toner. The toner opposes the latent image carrier while hopping in the vertical direction by this traveling wave electric field. It is conveyed to the development area.

In the region near the surface of the toner conveying member, the traveling wave electric field generated by the voltages applied to the plurality of electrodes is large, and the toner in the region near the surface accurately follows the traveling wave electric field.
In this case, the toner conveyance speed vt is calculated as r × n × f, where r is the electrode pitch, n is the number of electrode phases, and f is the frequency of the voltage applied to the electrodes.
Since the toner is conveyed in the air, the toner is conveyed while colliding with the air during the conveyance, and receives the viscous resistance of the air.
However, in the region near the surface, the force from the traveling wave electric field is greater than the air resistance, so that the toner is transported at the speed vt with little influence from the air resistance.
Conversely, air in the region near the surface creates a flow in the toner transport direction at the same vt speed as the toner in a steady state due to collision with the toner.
The air at a position slightly higher than the region near the surface with respect to the height in the normal direction of the toner conveying member is influenced by the flow of the air on the lower side and creates a flow in the toner conveying direction.
In this way, the toner in the region near the surface is transported at the speed of vt, so that the air in the region higher than the region near the surface with respect to the normal direction of the toner transport member also makes a flow in the toner transport direction. .

On the other hand, the traveling wave electric field decreases as the distance from the toner conveying member increases.
When the traveling wave electric field is reduced, the force that the toner receives from the traveling wave electric field is also reduced.
When the force received from the traveling wave electric field is reduced, the viscous resistance received from the air flow is relatively increased, and the toner is carried in the toner transport direction along the air flow.
When the viscous resistance of air becomes dominant among the forces received by the toner, the toner does not return to the surface of the conveying member, but is conveyed while drifting in the air on the air flow.
It can be said that such toner movement is no longer controlled by a traveling wave electric field.
When entering the development area in such a transport state, the air flow formed in the sky collides with the latent image carrier.
At that time, the toner floating in the air with the air also collides with the latent image carrier and adheres to the latent image carrier.
In this case, when the toner collides with the non-image portion of the latent image carrier, the toner adheres to the non-image portion, causing a background stain.
When developing a latent image of a solid image, most of the conveyed toner is developed on the latent image carrier, and therefore no air flows in the development area.

However, when developing a latent image with a small area ratio, such as an isolated dot latent image, most of the toner is transported by the traveling wave electric field as it is, and thus air flows in the developing region. In this case, the toner is attracted to the latent image by the force from the latent image electric field, but is subjected to a viscous resistance due to the flow of air, and flows without being developed.
Therefore, the dot latent image is not developed and image quality deterioration occurs.
In order to reduce the viscous resistance due to the air flow, it is conceivable to reduce the toner conveyance speed. Actually, the conveyance speed can be reduced by reducing the frequency of the voltage applied to the electrodes.
However, if the frequency is decreased, the contact time between the toner and the surface of the conveying member increases, and the toner conveyance performance is increased due to leakage of toner charge due to contact friction between the toner and the surface material of the conveying portion, and induction of mirror image charge. descend.
Therefore, the toner adheres to the surface of the conveying member and is not conveyed.

  As a conventional technique, the developer includes a developer transport unit that transports the developer by forming a non-uniform alternating electric field by applying a multilayer AC voltage to a plurality of electrodes arranged at predetermined intervals. A developing device that visualizes the electrostatic latent image by conveying the developer toward an image carrier on which the electrostatic latent image is formed by a conveying unit, wherein the developer conveying unit is formed from the surface of each electrode. There has been proposed a developing device configured such that the distance to the developer transport surface decreases stepwise as the developer transport direction proceeds (see, for example, Patent Document 1).

This developing device is configured such that the distance from the surface of each electrode to the developer transport surface decreases stepwise as the developer transport direction proceeds.
With such a configuration, it is possible to reliably generate a toner cloud in the development area while preventing the developer from scattering.
In this developing device, the traveling wave electric field on the developer transport surface can be increased by gradually reducing the distance from the surface of each electrode to the developer transport surface.

However, an increase in traveling wave electric field not only increases the electric field in the toner conveyance direction, but also increases the electric field in the hopping direction (normal direction from the surface of the conveyance member).
Therefore, the toner hops higher in the height direction.
Since the toner is moving also in the transport direction, an air flow is also generated.
The air flow in the vicinity of the surface also generates an air flow in a higher region.
By increasing the traveling wave electric field, the thickness of the flowing air layer is further increased.
In the region where the viscous resistance of air is larger than the force from the traveling wave electric field, the toner cannot be controlled by the traveling wave electric field and is carried while drifting in the air on the air flow.
Even if the toner enters the developing area in such a transport state, the toner is not clouded, but only on the air flow.
Therefore, the image quality deterioration as described above occurs.

By the way, by reducing the distance (development gap) between the toner conveying member and the latent image carrier, there is no flow of air over which the traveling wave electric field does not act effectively, and there is no gap between the toner conveying member and the latent image carrier. The toner can be controlled by a traveling wave electric field.
However, in this case, since the distance between the toner conveying member and the latent image carrier is small and the electric field in the direction of hopping the toner is large, the hopped toner reaches the non-image area before the kinetic energy decreases, Dirt will occur.

JP 2004-333845 A

  Therefore, in the present invention, for the purpose of solving the above-described conventional problems, attention is paid to the direction of traveling wave electric field, the conveyance time, and the frequency with respect to the toner conveyance direction, and the flow of air over the toner conveyance member is suppressed. Thus, toner adhesion on the surface of the conveying member is avoided, development efficiency and recovery efficiency are improved, and image quality is improved.

The present invention is a toner conveying device including a toner conveying member having a plurality of electrodes for generating a traveling wave electric field for conveying and hopping toner with electrostatic force, and the direction of the traveling wave electric field with respect to the toner conveying direction is , to a traveling-wave electric field across at repeat the forward and reverse directions Suyo at predetermined time intervals, by applying a traveling wave pulse to the plurality of electrodes are adapted so as to convey the toner in a predetermined direction A toner conveying device is provided.
Set in the present invention of claim 2, the conveying speed of the toner, the direction of the traveling wave electric field traveling wave pulse applying time when the conveyance direction and traveling-wave pulse applying time when the forward and backward direction of the toner Provided is a toner conveying device.
Set in the invention of claim 3, the conveying speed of the toner, the frequency of the traveling wave pulse when the direction of the traveling wave electric field frequency and backward traveling wave pulse when the transport direction and the forward direction of the toner Provided is a toner conveying device.
In the invention of claim 4, the conveying speed of the toner, the frequency of the traveling wave pulse applying time and the traveling wave pulse when the direction of the traveling wave electric field in the transport direction and the forward direction of the toner, the traveling wave when the reverse Provided is a toner conveying device which is set by pulse application time and traveling wave pulse frequency.

According to a fifth aspect of the present invention, there is provided a developing device that is arranged to face a latent image carrier and develops an electrostatic latent image on the latent image carrier. A developing device comprising the toner conveying device described above is provided.
According to a sixth aspect of the present invention, in the developing region where the latent image carrier and the toner conveying member face each other, the traveling wave electric field is directed at a certain time with respect to the toner conveying direction at a certain time interval. the total repeat the forward and reverse Suyo, by applying a traveling wave pulse to the plurality of electrodes, to provide a developing apparatus which is adapted to convey the toner in a predetermined conveying direction.
According to a seventh aspect of the present invention, the toner that is located downstream of the latent image carrier with respect to the toner conveyance direction and is opposed to the toner conveyance member and that has not contributed to development in the development region is collected. In the recovery region where the recovery means and the toner conveying member face each other, the direction of the traveling wave electric field with respect to the toner conveying direction is set to be forward in the entire traveling wave electric field every certain time. to repeat the reverse Suyo, by applying a traveling wave pulse to the plurality of electrodes, to provide a developing apparatus which is adapted to convey the toner in a predetermined conveying direction.
In the invention of claim 8, in both of the developing area and the recovery area, the direction of the traveling wave electric field with respect to the toner transport direction repeats the forward direction and the reverse direction for the entire traveling wave electric field at a certain time interval. to return Suyo, by applying a traveling wave pulse to the plurality of electrodes, to provide a developing apparatus which is adapted to convey the toner in a predetermined conveying direction.
According to a ninth aspect of the present invention, there is provided a developing device wherein the toner transport speed is set to 0.5 to 2.0 times the peripheral speed of the latent image carrier.

According to a tenth aspect of the present invention, there is provided an image forming apparatus provided with the above-described developing device.
According to an eleventh aspect of the present invention, there is provided a process cartridge having a structure in which at least one of a latent image carrier, a charging unit, and a cleaning unit in an electrophotographic process and the developing device described above are integrally held.
According to a twelfth aspect of the present invention, there is provided an image forming apparatus including a plurality of the process cartridges.

According to the present invention, the repeat the forward and reverse direction across the traveling wave electric field at regular time intervals with the direction of the traveling wave electric field with respect to the conveying direction of the toner Suyo, traveling wave pulse to the plurality of electrodes Is applied so that the toner is conveyed in the conveying direction, thereby suppressing the flow of air over the toner conveying member. As a result, the toner can be accurately controlled by the traveling wave electric field. Since the toner is transported in the reverse direction, the transport speed is reduced while moving the toner, so that the toner can be prevented from adhering to the surface of the transport member.

By setting the toner conveyance speed according to the traveling time pulse application time in the forward direction and in the reverse direction, the toner conveyance speed can be set accurately (claim 2).
By setting the toner transport speed according to the frequency of the traveling wave pulse in the forward direction and the reverse direction, the toner transport speed can be set accurately.
By setting the toner conveyance speed according to the traveling wave pulse application time in the forward direction and the reverse direction and the frequency of the traveling wave pulse, it is possible to accurately control the toner conveyance speed.
By providing the toner conveying device according to any one of claims 1 to 4 in the developing device, generation of air flow in the developing device can be suppressed (claim 5).
In total traveling wave electric field for each predetermined time with respect to the conveying direction of the toner is the direction of the traveling wave electric field to repeat Suyo the forward and backward direction in the developing area, by applying a traveling wave pulse to the plurality of electrodes Thus, by transporting the toner in the transport direction, the toner transport speed can be increased outside the development area, and the toner transport speed can be decreased in the development area. In addition, the development efficiency was improved by reducing the conveyance speed in the development area (claim 6).
In total traveling wave electric field at regular time intervals with the direction of the traveling wave electric field in the forward and reverse directions and the repeat Suyo to the conveying direction of the toner in the recovery area, by applying a traveling wave pulse to the plurality of electrodes Thus, by transporting the toner in the transport direction, the toner transport speed can be increased outside the recovery area, and the toner transport speed can be decreased in the recovery area. In addition, the collection efficiency was improved by reducing the conveyance speed in the collection area (claim 7).
To repeat the forward across the traveling wave electric field at regular time intervals with the direction of the traveling wave electric field in both the developing area collection region to the conveying direction of the toner and the opposite direction Suyo, traveling to the plurality of electrodes By applying the wave pulse to transport the toner in the transport direction, the transport speed is reduced in the development region and the recovery region, and the development efficiency and the recovery efficiency are improved (claim 8).
By setting the transport speed of the toner transported on the toner transport device from 0.5 times to 2.0 times the peripheral speed of the latent image carrier, it is possible to achieve both development of an isolated dot and solid image. (Claim 9).

  Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following examples.

A developing device provided with the toner conveying device of the present invention will be described with reference to FIGS.
The developing device 10 in FIG. 1 uses a two-component developer composed of a magnetic carrier and a non-magnetic toner.
The developing device 10 includes a latent image carrier 11 and a toner transport device 12.
In the development area of the latent image carrier 11, the toner adheres to the latent image on the photosensitive drum to be visualized, and the toner that has not contributed to the development is collected in a predetermined collection area.

The toner conveying device 12 includes a toner conveying member 13 having a plurality of electrodes 14 for generating a traveling wave electric field for conveying and hopping toner with electrostatic force.
In the toner transport device 12, toner is supplied from the toner replenishing port 15 and is sent to the developer storage unit 16.
The developer accommodating portion 16 is divided into two chambers and is connected by developer passages (not shown) at both ends in the developing device.
A two-component developer is accommodated in the developer accommodating portion 16 and is conveyed while being agitated by the agitating and conveying screw 17 in each chamber.

The developer storage unit 14 is provided with a toner concentration sensor (not shown) that detects the magnetic permeability of the developer, thereby detecting the developer concentration.
When the toner concentration in the developer accommodating portion 16 decreases, the toner is replenished from the toner replenishing port 15 to the developer accommodating portion 16.
A developer carrier 18 is disposed at a position facing the agitating and conveying screw 17.
A fixed magnet is disposed inside the developer carrier 18, and the developer in the developer container 16 is pumped up to the surface of the developer carrier 18 by the rotation and magnetic force of the developer carrier 18.

A developer layer regulating member 19 is provided at a position facing the developer carrier 18 upstream of the developer pumping position in the rotation direction of the developer carrier 18. The developer pumped up at a predetermined pumping position is regulated to a certain amount of developer layer thickness by the developer layer regulating member 19.
The developer that has passed through the developer layer regulating member 19 is conveyed to a position facing the toner conveying member 13 as the developer carrier 18 rotates.
A supply bias is applied to the developer carrier 18 by the first voltage application means 21.
A voltage is applied to the toner conveying member 13 by the second voltage applying means 22 to the electrode 14.
At a position facing the toner conveying member 13, an electric field is generated between the toner conveying member 13 and the developer carrier 18 by the first and second voltage applying means 21 and 22.
Under the electrostatic force from the electric field, the toner dissociates from the carrier and moves to the surface of the toner transport member 13.
The toner that has reached the surface of the toner transport member is transported while hopping on the surface of the toner transport member by the transport electric field generated by the voltage applied by the second voltage applying unit 22.
The toner conveyed by the conveying electric field to a position facing the latent image carrier 11 is developed on the latent image carrier 11 by the developing electric field between the toner conveying member 13 and the image portion on the latent image carrier 11. The
The toner that has not contributed to the development is further conveyed by the toner conveying member 13 and is collected from the surface of the toner conveying member by a collecting means (not shown).
The collected toner is returned again to the developer container 16 and circulates in the developing device 10.

FIG. 2 shows a schematic configuration diagram of another example of the developing device of the present invention.
The developing device 20 in FIG. 2 shows an example of a developing device using a one-component developer made of nonmagnetic toner.
The toner is accommodated in the developer accommodating portion 16, and the toner is frictionally charged with the developer carrier 18 by the toner replenishing roller 23, and is pumped up onto the developer carrier 18 by electrostatic force.
The toner on the developer carrier 18 is made into a thin layer by the developer layer regulating member 19, and is conveyed to a position facing the toner conveying member 13 as the developer carrier 18 rotates.
A supply bias is applied to the developer carrier 18 by the first voltage application means 21.
A voltage is applied to the toner conveying member 13 by the second voltage applying means 22 to the electrode 14.
At a position facing the toner conveying member 13, an electric field is generated between the toner conveying member 13 and the developer carrier 18 by the first and second voltage applying means 21 and 22.
Under the electrostatic force from the electric field, the toner dissociates from the developer carrier 18 and moves to the surface of the toner conveying member 13.
The toner that has reached the surface of the toner transport member 13 is transported while hopping on the surface of the toner transport member 13 by the transport electric field generated by the voltage applied by the second voltage applying unit 22.
The toner conveyed by the conveying electric field to a position facing the latent image carrier 11 is developed on the latent image carrier 11 by the developing electric field between the toner conveying member 13 and the image portion on the latent image carrier 11. The
The toner that has not contributed to the development is further conveyed by the toner conveying member 13 and is collected from the surface of the toner conveying member by a collecting means (not shown).
The collected toner is returned again to the developer container 16 and circulates in the developing device 20.

In the developing devices 10 and 20 configured as described above, when the toner is transported on the toner transport member 13, the direction of the traveling wave electric field repeats the forward direction and the reverse direction with respect to the toner transport direction, and the toner transport direction. (Claim 1).
FIG. 3 shows an example of a traveling wave pulse in the case where toner is conveyed by repeating forward and reverse feeding.
Here, an example is shown in which the application time of the backward traveling wave pulse is shorter than the application time of the forward traveling wave pulse, and the frequency is set to be the same.
The toner conveyance speed v by the traveling wave electric field is v = f × r × n.
f: repetition frequency of pulse applied to one of the electrodes for generating traveling wave electric field r: electrode pitch for generating traveling wave electric field n: number of phases of traveling wave electric field.
The application time of the forward traveling wave pulse and ts, when the application time tr reverse traveling wave pulses, the transport distance X ₁ in the case of carrying forward, repeating the reverse direction, X ₁ = v · ts −v · tr.
For example, when the pulse repetition frequency f = 7 kHz, the electrode pitch r = 0.06 mm, and the number of phases of the traveling wave electric field is n = 3, the toner conveyance speed v is v = 1.26 m / sec, and the forward direction Assuming that the traveling wave pulse application time ts = 4 msec and the backward traveling wave pulse application time tr = 2 msec, the toner transport distance X in the case of repeatedly transporting in the forward and reverse directions is 2.52 mm.
On the other hand, when no traveling wave in the reverse direction is applied, that is, when both ts and tr are transported with a traveling wave in the forward direction, the transport distance X ₂ is 7.56 mm. In this example, the forward direction and the reverse direction are repeated. As a whole, the speed can be reduced to substantially 1/3.
FIG. 3 is an example in which the forward direction and the reverse direction are switched based on the A phase in the three-phase pulses of the A phase, the B phase, and the C phase, and the time for six cycles of the A phase pulse is the forward direction, A traveling wave pulse in the direction of A phase → B phase → C phase is a traveling wave pulse in the direction of reverse C phase → B phase → A phase for three periods.

Next, an example of a traveling wave pulse when the toner is conveyed by repeating the forward and reverse feeding will be described with reference to FIG.
In this example, the forward traveling wave pulse application time and the backward traveling wave pulse application time are the same, but the forward frequency is set higher than the reverse frequency. ).
The toner conveyance speed v by the traveling wave electric field is v = f × r × n as in the example shown in FIG.
Then, assuming that the frequency fs of the forward traveling wave pulse, the frequency fr of the backward traveling wave pulse, and the repetition time t, the transport distance X ₁ when transporting the forward direction and the reverse direction repeatedly is X ₁ = fs * r * n * t-fr * r * n * t = (fs-fr) r * n * t.
For example, a forward pulse frequency fs = 6 kHz, a reverse pulse frequency fr = 3 kHz, an electrode pitch r = 0.06 mm, a traveling wave electric field phase number n = 3, and a forward / reverse traveling wave pulse repetition time t = 1 msec. The toner transport distance X ₁ in the case of repeatedly transporting the forward direction and the reverse direction is 0.54 mm.
On the other hand, when the traveling wave in the reverse direction is not applied, that is, when the traveling wave in the forward direction is transported at the frequency fs = 6 kHz for the time 2t, the transport distance X ₂ is X ₂ = fs × r × n × 2t = 2. .16 mm.
In the example of FIG. 4, the transport distance X _{1 in} which the forward direction and the reverse direction are repeated can be reduced to a substantially 1/4 speed as a whole with respect to X ₂ only in the forward direction.
FIG. 4 is an example in which the forward direction and the reverse direction are switched with reference to the A phase in the three-phase pulses of the A phase, the B phase, and the C phase, and the six periods of the A phase pulse at the frequency fs are in the forward direction. That is, a traveling wave pulse in the direction of A phase → B phase → C phase, and three periods at a frequency fr are traveling wave pulses in the direction of reverse C phase → B phase → A phase.

  As described above, FIG. 3 is an embodiment in which the application time of the backward traveling wave pulse is shorter than the application time of the forward traveling wave pulse and the frequency is set to be the same, and FIG. Although the application time of the forward traveling wave pulse is the same as the application time of the backward traveling wave pulse, the forward frequency is set to a higher value than the reverse frequency, but the time and frequency are appropriately combined. (Claim 4) It is of course possible to set the actual conveyance speed to an optimum low value as required.

The developing device of the present invention includes the toner conveying member as described above (Claim 5).
By transporting the toner in the transport direction while the direction of the traveling wave electric field repeats the forward direction and the reverse direction with respect to the toner transport direction, a steady air flow in one direction does not occur on the toner transport member 13.
Therefore, the toner can be accurately controlled by the traveling wave electric field without flowing in the air flow.
Further, since the conveyance speed is reduced while moving the toner, it is possible to avoid the adhesion of toner to the surface of the toner conveyance member 13.

In the developing device of the present invention, in the developing region where the latent image carrier 11 and the toner conveying member 13 face each other, the direction of the traveling wave electric field repeats the forward direction and the reverse direction with respect to the toner conveying direction. It is made to convey in the predetermined conveyance direction (Claim 6).
In a supply region where the toner conveying member 13 and the developer carrying member 18 are opposed to each other, an electric field for moving the toner from the developer carrying member 18 onto the toner carrying member 13 is generated by the first voltage applying unit 21.
If the toner conveyance speed is low in this supply area, the toner may adhere to the surface of the conveyance member 13, and therefore it is preferable that the conveyance speed is high in the supply area.
In the transport region between the supply region and the development region, it is necessary to transport the toner that has moved to the toner transport member 13 in the supply region to the development region as quickly as possible, and it is preferable that the transport speed in the transport region is high.
Therefore, the toner is conveyed while repeating the forward direction and the reverse direction only in the development region.
The toner conveyance speed in the development region is set by time and frequency in the forward direction and in the reverse direction, but is preferably set to 0.5 to 2.0 times the peripheral speed of the latent image carrier 11 (claims). Item 9).
The toner conveyance speed is determined by the image quality after development. When the toner conveyance speed is low, the time during which the toner is in the development area is long. Therefore, a one-dot latent image or the like is easily developed.
However, in the case of solid image development, a lot of toner is required for development, and new toner needs to be conveyed as soon as the toner is used for development.
Therefore, if the toner transport speed is too low, the amount of toner necessary for solid development is not transported, causing problems such as insufficient density.
When the toner transport speed is high, new toner is transported as soon as the toner is used for development, so that the problem of insufficient density does not occur. However, when developing a one-dot latent image, if the toner transport speed is high, the toner is not easily attracted to the one-dot latent image because the speed in the transport direction is high. For this reason, there arises a problem that the one-dot latent image is not sufficiently developed.

As described above, in order to establish both 1-dot development and solid development, the toner transport speed needs to be within a certain numerical range.
Table 1 below shows the evaluation of the developability of the isolated 1-dot latent image and the developability of the solid image when the ratio of the toner conveyance speed to the peripheral speed of the latent image carrier 11 is changed.

As shown in Table 1, when the ratio of the toner transport speed to the peripheral speed of the latent image carrier 11 is 0.3, the transport speed is too slow to catch up with the solid development, and the solid image is normally developed. Not (evaluation ×).
When the ratio is 2.2, the one-dot latent image is not normally developed because of the high conveyance speed (evaluation x).
When the ratio is 0.5 to 2.0, both the 1-dot latent image and the solid image are normally developed and can be compatible (evaluation ◯).
Therefore, it is preferable to set the toner conveyance speed in the development region to 0.5 to 2.0 times the peripheral speed of the latent image carrier.

A collecting unit is provided on the downstream side of the developing region in the toner conveyance direction.
Various methods are conceivable as the recovery means. FIG. 5 is a diagram showing toner recovery by the recovery plate 30.
An electric field is generated between the toner conveying member 13 and the collecting plate 30 so that a force acts on the toner in a direction from the toner conveying member 13 toward the collecting plate 30.
The toner that has not contributed to development in the development area moves from the toner conveying member 13 to the collecting plate 30 in the collecting area 32 where the collecting plate 30 and the toner conveying member 13 face each other.
When a certain amount of toner accumulates on the collection plate 30, the collection plate 30 is vibrated by the vibrator 31, the toner on the collection plate 30 is shaken off, and returned to the developer storage unit 16 again.

FIG. 6 is a view showing collection by the collection roller 40.
An electric field is generated between the toner conveying member 13 and the collecting roller 40 so that a force acts on the toner in a direction from the toner conveying member 13 toward the collecting roller 40.
The toner that has not contributed to the development in the development area moves from the toner conveying member 13 to the collecting roller 40 in the collecting area 42 where the collecting roller 40 and the toner conveying member 13 face each other.
The toner adhering to the collection roller 40 is scraped off by the blade 41 and returned to the developer accommodating portion.

FIG. 7 is a view showing collection by the brush roller 50.
An electric field is generated between the toner conveying member 13 and the brush roller 50 so that a force acts on the toner in a direction from the toner conveying member 13 toward the brush roller 50.
The toner that has not contributed to development in the development area moves from the toner conveyance member 13 to the brush roller 50 in the collection area 52 where the brush roller 50 and the toner conveyance member 13 face each other.
The toner adhering to the brush roller 50 is scraped off by the flicker bar 51 and returned to the developer accommodating portion 16 again.

FIG. 8 is a diagram showing collection by the suction nozzle 60.
The suction nozzle 60 and the toner conveying member 13 are opposed to each other, and air is sucked from the suction nozzle 60 by the suction pump 63.
A seal 61 is attached downstream of the suction nozzle 60 in the toner conveyance direction, and this seal 61 is in contact with the surface of the toner conveyance member 13.
The toner that has not contributed to the development in the development area is collected through the suction nozzle 60 on the air flow in the collection area 62.
The toner that is not carried by the air flow and is conveyed by the traveling wave electric field also collides with the seal 61 and is not conveyed downstream as it is.
The toner collected by the suction nozzle 60 is returned to the developer accommodating portion 16 through the duct 64 again.

In the various collection methods described above, it is advantageous to improve the collection efficiency when the toner conveyance speed immediately before the collection is small.
When the toner conveyance speed is high, the collection by the collection plate 30, the collection roller 40, and the brush roller 50 shortens the time during which the force in the direction toward the collection unit acts on the toner.
In such a case, it is difficult to reliably collect with such a collecting means, and toner conveyed further downstream is generated by the traveling wave electric field.
Such toner is transported to the supply area again, but cannot pass through the supply area and adheres to the toner transport member before the supply area.
In the collection by the suction nozzle 60, if the toner conveyance speed is larger than the toner suction speed, the toner stagnates on the conveyance member, and toner adhesion occurs before the collection area.
In order to increase the suction speed, it is necessary to improve the performance of the suction pump 63, resulting in an increase in cost.
Therefore, in the collection region, the collection efficiency is improved when the toner conveyance speed is as low as possible.

As described above, in the collection regions 32, 42, 52, and 62, the toner can be transported in the transport direction while the traveling wave electric field repeats the forward direction and the reverse direction with respect to the toner transport direction. Desirable (Claim 7).
By repeating the forward direction and the reverse direction, the conveyance speed can be reduced without causing toner to adhere to the conveyance member, and the collection efficiency can be increased.

In the above description, the development area and the collection area are described separately. However, in both the development area and the collection area, the direction of the traveling wave electric field repeats the forward and reverse directions with respect to the toner conveyance direction. It is also possible to carry it to (Claim 8).
In this case, the toner may be conveyed while repeating the forward direction and the reverse direction from the developing area entrance to the collecting area on the toner conveying member 13, or the developing area and the collecting area repeat the forward direction and the reverse direction. The toner may be conveyed only in the forward direction in the area between them.
By doing so, both development efficiency and recovery efficiency can be improved.

The developing device 10 of the present invention can be incorporated as a component of a conventionally known image forming apparatus.
A general image forming apparatus will be described. In the image forming apparatus, a photosensitive drum as a latent image carrier is uniformly charged by a charging device, and an electrostatic latent image is formed on the surface of the photosensitive drum by writing with a laser beam according to an image read from an exposure unit. Is done.
The electrostatic latent image on the surface of the photosensitive drum is visualized by attaching toner to the above-described developing devices 10 and 20 of the present invention, and the visible image is transferred from the paper feeding cassette. The transfer paper onto which the visible image is transferred is transferred to a paper (recording medium) by a transfer roller to which a voltage from a transfer power source is applied. The transfer paper is separated from the surface of the photosensitive drum and passes between the rollers of the fixing unit. Thus, the visible image is fixed and discharged to a discharge tray outside the apparatus.

In addition, a process cartridge that holds the above-described image forming apparatus and the developing device of the present invention can be manufactured. Further, an image forming apparatus including a plurality of process cartridges for each color can be configured. it can.
Here, the process cartridge is integrally provided with a drum-shaped photoconductor as an image carrier, a charging roller, a developing device, a cleaning blade, etc. in a predetermined case, and is attached to and detached from the image forming apparatus main body. It shall be configured as possible.

1 is a schematic configuration diagram of an example of a developing device of the present invention. The schematic block diagram of other examples of the image development apparatus of this invention is shown. An example of a traveling wave pulse in the case where toner is conveyed by repeating forward and reverse feeding will be described. An example of a traveling wave pulse in the case where toner is conveyed by repeating forward and reverse feeding will be described. FIG. 6 is a diagram illustrating toner recovery by a recovery plate. It is the figure which showed collection | recovery by a collection | recovery roller. It is the figure which showed collection | recovery by a brush roller. It is the figure which showed collection | recovery by a suction nozzle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Developing device 11 Latent image carrier 12 Toner conveying device 13 Toner conveying member 14 Electrode 15 Toner replenishing port 16 Developer accommodating portion 17 Agitating and conveying screw 18 Developer carrying member 19 Developer layer regulating member 20 Developing device 21 First voltage application Means 22 Second voltage applying means 23 Toner supply roller 30 Collection plate 31 Vibrator 32 Collection area 40 Collection roller 41 Blade 42 Collection area 50 Brush roller 51 Flicker bar 52 Collection area 60 Suction nozzle 61 Seal 62 Collection area 63 Suction pump 64 Duct

Claims (12)

A toner conveying device comprising a toner conveying member having a plurality of electrodes for generating a traveling wave electric field for conveying and hopping toner with electrostatic force,
Direction of the traveling wave electric field for carrying direction of the toner, to a certain Suyo throughout traveling wave electric field repeat the forward and reverse direction for each predetermined time, by applying a traveling wave pulse to the plurality of electrodes, the toner A toner transporting device, wherein the toner transporting device is transported in a predetermined direction. The toner conveyance speed is set by a traveling wave pulse application time when the traveling wave electric field direction is the toner conveyance direction and the forward direction, and a traveling wave pulse application time when the direction is the reverse direction. Item 2. The toner conveying device according to Item 1. The toner conveying speed is set by a traveling wave pulse frequency when the traveling wave electric field is in the forward direction and a toner conveying direction and a traveling wave pulse frequency when the direction is the reverse direction. Item 2. The toner conveying device according to Item 1. Conveying speed of the toner, when the direction of the traveling wave electric field in the transport direction and the forward direction of the toner and the frequency of the traveling wave pulse applying time and a traveling wave pulses, in the case of the backward traveling wave pulse applying time and the traveling wave pulse The toner conveying device according to claim 1, wherein the toner conveying device is set by a frequency. A developing device that is arranged to face a latent image carrier and develops an electrostatic latent image on the latent image carrier,
A developing device comprising the toner conveying device according to claim 1. In the developing area where the latent image carrier and the toner conveying member face each other, the direction of the traveling wave electric field is changed in the forward direction and the reverse direction in the traveling wave electric field for a certain time with respect to the toner conveying direction. to repeat Suyo, by applying a traveling wave pulse to the plurality of electrodes, the developing device according to claim 5, characterized in that is adapted to convey the toner in a predetermined conveying direction. A recovery means for recovering toner that is located downstream of the latent image carrier with respect to the toner transport direction and is opposed to the toner transport member and that has not contributed to development in the development region;
Wherein the recovery means, the collection area where the toner conveying member faces, repeat the forward and reverse direction across the traveling wave electric field for each predetermined time with respect to the conveying direction of the toner is the direction of the traveling wave electric field Suyo 6. The developing device according to claim 5 , wherein a traveling wave pulse is applied to the plurality of electrodes to convey the toner in a predetermined conveyance direction. Said developing region, both in the collection area, the whole traveling wave electric field at regular time intervals with the direction of the traveling wave electric field with respect to the conveying direction of the toner in the forward and reverse directions repeatedly Suyo, said plurality of 8. The developing device according to claim 7 , wherein a traveling wave pulse is applied to the electrode to convey the toner in a predetermined conveyance direction.   9. The developing device according to claim 5, wherein a toner conveyance speed is set to 0.5 to 2.0 times a peripheral speed of the latent image carrier.   An image forming apparatus comprising the developing device according to claim 5. At least one of a latent image carrier, charging means, and cleaning means in an electrophotographic process;
10. A process cartridge comprising the developing device according to claim 5 integrally held therein.   An image forming apparatus comprising a plurality of process cartridges according to claim 11.

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