JP2009020209A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device designed so that a quantity of toner attached to the surface of a latent image carrier is made constant by controlling a quantity of electrification of toner on a toner carrier. <P>SOLUTION: The developing device 20 has the toner carrier 21 disposed opposite a latent image carrier 10 and holding toner to develop an electrostatic latent image on the latent image carrier. The developing device 20 has a voltage application means 28 that has a plurality of electrodes arranged at predetermined intervals within the toner carrier 21 and applies voltages to the electrodes so that electric fields between the electrodes vary with time. The developing device is configured to cause toner on the toner carrier to fly by the electric fields between the electrodes, thereby forming a cloud. The device also has a toner electrification amount control means for controlling an amount of electrification of toner on the toner carrier. By controlling the amount of electrification of toner on the toner carrier, therefore, an amount of electrification of toner involved in development is kept constant all the time and thus a stable and satisfactory image is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a developing device that develops an electrostatic latent image on a latent image carrier using toner, a process cartridge that includes the developing device, and a copier and printer that include the developing device or the process cartridge. The present invention relates to an image forming apparatus such as a plotter, a facsimile, or a complex machine of these.

  Conventionally, a multiphase AC voltage is applied to each electrode of the transport path to form a traveling wave electric field, and the developer is transported to the latent image carrier on the transport path by the traveling wave electric field. A developing device for developing an electrostatic latent image on a latent image carrier by supplying it to the latent image carrier, comprising: a control means for adjusting a transport amount of the developer on the transport path. It has been proposed (see, for example, Patent Document 1).

  In addition, in the image forming apparatus for forming a color image, the developing apparatus is configured to hold and supply a developer for developing the electrostatic latent image formed on the latent image carrier, with a predetermined interval on the substrate. And a plurality of electrodes arranged in such a manner that the developer is conveyed to a developing region facing the latent image carrier by a traveling wave electric field formed by applying a multiphase AC voltage to the electrodes. In addition, there has been proposed a developing device characterized in that the amount of developer conveyed to the developing area can be changed (see, for example, Patent Document 2).

  Further, as previously published by the present applicant, in a developing device for developing a latent image on a latent image carrier by attaching powder onto the latent image carrier, A conveying member having a plurality of electrodes disposed opposite to each other for generating a traveling-wave electric field for moving the powder, and the powder is disposed on the electrode of the conveying member with respect to the image portion of the latent image. An n-phase potential is applied to the non-image portion so as to form an electric field in a direction toward the opposite side of the latent image carrier toward the latent image carrier. A developing device has been proposed (Patent Document 3).

JP 2004-101933 A JP 2004-170796 A JP 2004-198675 A

  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 the toner on the toner carrier is made into a cloud to supply the toner onto the latent image carrier. The toner carrier is disposed to face the latent image carrier, and a plurality of electrodes are disposed at a predetermined pitch therein. A voltage that changes with time is applied to the plurality of electrodes, and the toner on the toner carrying member is caused to fly by an electric field between the electrodes to form a cloud.

  In the case of the toner carrier having such a configuration, there are three methods for conveying the toner. One is a method in which the electrode has three or more phases, the toner carrier does not rotate, and the toner is hopped by the electric field between the electrodes and is also conveyed in the conveyance direction. The second method is a method in which the electrodes are two-phased and are clouded by hopping the toner while reciprocating the electric field between the electrodes, and the toner is conveyed by rotating the toner carrier. The last is a method of conveying by both rotation of the toner carrier and an electric field between the electrodes.

In either method, the toner transported to the development area is hopped in the vertical direction, and in the direction toward the latent image carrier in the image portion of the latent image carrier, and in the direction toward the toner carrier in the non-image portion. In response, the image portion is developed.
A voltage obtained by superimposing a pulse voltage on a DC voltage is applied to each electrode of the toner carrier, and the toner is clouded on the toner carrier. In this case, the developing bias is obtained by adding a cloud potential, which is the potential of the clouded toner, to the potential of the DC voltage component applied to each electrode of the toner carrier.

  Two methods are conceivable in order to keep the toner adhesion amount on the latent image carrier constant. One is a method in which the development difference is completed when the potential difference between the development bias and the image portion potential is sufficiently large and all the toner on the toner carrier is developed. In this case, what controls the amount of adhesion on the latent image carrier is the amount of toner on the toner carrier. The other is that a sufficient amount of toner is placed on the toner carrier, and the toner is developed so as to fill in the difference between the potential of the image portion and the potential of the developing bias. When the potential difference disappears, the development is completed. It is a method of doing. In this case, what controls the amount of adhesion on the latent image carrier is the difference between the image portion potential and the potential of the developing bias and the charge amount of the toner.

  In the case of the former method, the amount of adhesion differs between when developing a solid image and when developing an image with a low area ratio. In the case of an image with a low area ratio, since the toner is clouded, not only the toner on the toner carrying member facing the latent image but also the toner hopping around the toner image becomes a latent image. As a result, the amount of adhesion increases. Therefore, the latter method is desirable when developing with clouded toner. In the latter method, when the charge amount of the toner is large, the potential difference between the development bias and the image portion potential is eliminated with a small amount of toner, and the adhesion amount on the latent image carrier is reduced. On the contrary, when the charge amount of the toner is small, the adhesion amount on the latent image carrier increases. Therefore, in order to make the adhesion amount on the latent image carrier constant, it is necessary to control the toner charge amount to be constant.

  The toner supplied to the toner carrier by the toner supply means is conveyed to the development area while repeating hopping by the electric field between the electrodes. At this time, charge transfer occurs due to contact friction between the toner and the surface of the toner carrier. Whether the toner charge amount increases or decreases due to hopping depends on the frictional charging characteristics between the toner and the surface of the toner carrier. In any case, the charge amount of the toner is determined by the number of contact between the toner and the surface of the toner carrier. The number of contact between the toner and the surface of the toner carrier is the number of hops of the toner, and the number of toner hops is proportional to the number of switching of the pulse voltage applied to each electrode of the toner carrier. Therefore, the charge amount of the toner on the toner carrier can be controlled by controlling the number of switching of the pulse voltage.

  In order to control the charge amount of the toner, it is necessary to detect the charge amount. The characteristic value corresponding to the toner charge amount is the hopping height of the toner. When the charge amount of the toner is large, the force that the toner receives from the electric field increases. The electric field strength on the toner carrier decreases as the distance from the surface of the toner carrier decreases, but the toner can be hopped to a high position due to the large amount of charge. On the other hand, when the charge amount of the toner is small, the force received from the electric field is small, and the toner cannot be hopped to a high position. Therefore, the toner charge amount can be known by detecting the toner hopping height.

In the prior art described in Patent Document 1 and Patent Document 2 described above, the amount of developer attached on the latent image carrier is detected, and the amount of developer conveyed to the development area is controlled. When the detected adhesion amount is large, the amount of developer conveyed is reduced, and when the adhesion amount is small, the amount of developer conveyed is increased.
In the case of this conventional technique, the amount of adhesion of the solid image on the latent image carrier can be controlled by the former developing method described above, but a difference in the amount of adhesion of the solid image and the image having a low area ratio occurs, which is a problem. Become. In the latter development method described above, the amount of adhesion on the latent image carrier cannot be controlled even if the amount of toner on the toner carrier is controlled.

  The present invention has been made in view of the above circumstances, and with the latter development method described above, the amount of toner on the toner carrier can be controlled to control the amount of adhesion on the latent image carrier to be constant. It is an object of the present invention to provide a developing device having a configuration, and further to provide a process cartridge and an image forming apparatus including the developing device.

  As a means for solving the above-described problems, the present invention utilizes the contact friction between the toner and the toner carrier, and carries the toner while reaching the development area from the supply area or between the regulation area and the development area. The number of contact between the toner and the toner carrier is controlled by controlling the number of switching of the voltage applied to the body electrode. Specifically, the frequency of the pulse voltage applied to the electrode and the line of the toner carrier are controlled. The number of switching is controlled by controlling the speed. Further, the charge amount of the toner on the toner carrier is optically detected, and the charge amount of the toner is controlled based on the detection result. More specifically, the present invention employs the following solutions.

  According to a first aspect of the present invention, there is provided a developing device including a toner carrier that is disposed opposite to a latent image carrier and carries toner for developing an electrostatic latent image on the latent image carrier. A plurality of electrodes arranged at a predetermined interval inside the toner carrier, and a voltage applying means for applying a voltage to the electrodes so that an electric field between the plurality of electrodes changes with time; And a toner charge amount control means for controlling the charge amount of the toner on the toner carrier. .

  According to a second means of the present invention, in the developing device of the first means, there is provided a toner supply means for supplying toner to the toner carrier, and in a supply region where the toner supply means and the toner carrier are opposed to each other. The supplied toner is transported to a development region where the latent image carrier and the toner carrier are opposed to each other by rotation of the toner carrier, and each of the electrodes supplies the toner charge amount control means. It is a switching number control means for controlling the number of times the applied voltage is switched before moving from the region to the development region.

  According to a third means of the present invention, in the developing device of the first means, a toner supply means for supplying toner to the toner carrier, and a toner for regulating the toner supplied to the toner carrier by the toner supply means A toner having a layer regulating member, and the toner regulated by the toner layer regulating member is transported to a developing region where the latent image carrier and the toner carrier are opposed to each other by rotation of the toner carrier; The charge amount control means is a switching number control means for controlling the number of times that the applied voltage is switched until each electrode moves from the restriction area where the toner carrier and the toner layer restriction member face each other to the development area. It is characterized by being.

According to a fourth means of the present invention, in the developing device of the second or third means, the switching frequency control means controls the frequency of the voltage applied by the voltage application means.
The fifth means of the present invention is characterized in that, in the developing device of the second or third means, the switching frequency control means controls the linear velocity of the toner carrier.
Further, according to a sixth means of the present invention, in the developing device of the second or third means, the switching number control means is configured such that both the frequency of the voltage applied by the voltage application means and the linear velocity of the toner carrier are provided. It is characterized by controlling.

According to a seventh means of the present invention, in the developing device of any one of the first to sixth means, a charge amount detecting means for detecting the charge amount of the toner on the toner carrier is provided. .
According to an eighth means of the present invention, in the developing device of the seventh means, the toner carrier is rotated at a position downstream of the supply area or the restriction area and upstream of the development area. A charge amount detecting means is provided.
Further, according to a ninth means of the present invention, in the developing device of any one of the first to eighth means, the switching number control means controls the number of electrode switching based on the detection result of the charge amount detecting means. It is characterized by that.

The tenth means of the present invention is the developing apparatus of any one of the seventh to ninth means, wherein the charge amount detecting means is a height direction of the toner on the toner carrier from the surface of the toner carrier. It is characterized by detecting the position of.
According to an eleventh means of the present invention, in the developing device of any one of the seventh to tenth means, the charge amount detecting means comprises a light emitting element and a light receiving element.
The twelfth means of the present invention is the developing device of the eleventh means, wherein the light emitting element projects light onto a toner conveyance path conveyed by rotation on the toner carrier, and the light receiving element is a toner. Detecting the transmitted light without being scattered by the light.
Furthermore, the thirteenth means of the present invention is the developing device of the eleventh means, wherein the light emitting element projects light onto a toner transport path transported by rotation on the toner carrier, and the light receiving element Is characterized by detecting diffused light scattered by the toner.
Further, the fourteenth means of the present invention is the developing device of the eleventh means, wherein the light emitting element projects light onto a toner conveyance path conveyed by rotation on the toner carrier, and the light receiving element. Is characterized by detecting both light transmitted without being scattered by the toner and diffused light scattered by the toner.

The fifteenth means of the present invention develops the latent image by attaching toner to the latent image on the latent image carrier, and finally transfers the toner image obtained thereby to a recording material to form an image. In the image forming apparatus, the developing device of any one of the first to fourteenth means is provided as means for developing the latent image on the latent image carrier.
According to a sixteenth means of the present invention, in the image forming apparatus of the fifteenth means, an image obtained by superimposing a plurality of toner images formed on the latent image carrier is formed on a recording material. Features.

A seventeenth means of the present invention is a process cartridge provided in an image forming apparatus for forming an image by an electrophotographic process, wherein at least one of a latent image carrier, a charging means, and a cleaning means, The developing device of any one of the fourteenth means is integrally held and is detachably provided to the image forming apparatus.
The eighteenth means of the present invention is an image forming apparatus for forming an image by an electrophotographic process, comprising a plurality of process cartridges of the seventeenth means, and forming a single color, multicolor or full color image. And

Since the developing device of the first means includes a toner charge amount control means for controlling the charge amount of the toner on the toner carrier, by controlling the charge amount of the toner on the toner carrier, The charge amount of the toner entering the development can always be constant, and a stable and good image can be formed.
In the developing device of the second means, in addition to the effects of the first means, the toner is supplied to the toner carrier by the toner supply means, the toner is hopped by the electric field between the electrodes, and the toner is rotated by the rotation of the toner carrier. In the configuration in which the toner is conveyed to the development area, the charge amount of the toner in the development area can be controlled by controlling the number of times the voltage applied to the electrode is switched from the supply area to the development area.
Further, in the developing device of the third means, in addition to the effects of the first means, the toner is supplied to the toner carrier by the toner supply means, the toner layer is regulated by the toner regulating member, and the toner is applied by the electric field between the electrodes. In the configuration where toner is transported to the development area by hopping and rotating the toner carrier, the charge amount of toner in the development area is controlled by controlling the number of times the voltage applied to the electrode is switched from the regulation area to the development area. can do.

In the developing device of the fourth means, in addition to the effects of the second or third means, the frequency of switching can be controlled by controlling the frequency of the voltage applied by the voltage applying means.
In the developing device of the fifth means, in addition to the effects of the second or third means, the number of times of switching can be controlled by controlling the linear velocity of the toner carrier.
Further, in the developing device of the sixth means, in addition to the effects of the second or third means, the frequency of switching is controlled by controlling both the frequency of the voltage applied by the voltage applying means and the linear velocity of the toner carrier. can do.

In the developing device of the seventh means, in addition to the effect of any one of the first to sixth means, a toner charge amount detection means for detecting the charge amount of the toner on the toner carrier is provided, thereby charging the toner. The amount can be grasped.
In the developing device of the eighth means, in addition to the effects of the seventh means, a charge amount detecting means is provided at a position downstream of the developing area downstream of the supply area or the regulating area with respect to the rotation direction of the toner carrier. As a result, the charge amount of the toner entering the developing area can be detected.
Further, in the developing device of the ninth means, in addition to the effect of any one of the first to eighth means, the switching number control means controls the number of electrode switching based on the detection result of the charge amount detecting means. The charge amount of the toner on the toner carrier can be controlled based on the detection result.

In the developing device of the tenth means, in addition to the effect of any one of the seventh to ninth means, the position in the height direction of the toner on the toner carrier corresponding to the toner charge amount is detected. Thus, the charge amount of the toner can be accurately detected.
Further, in the developing device of the eleventh means, in addition to the effect of any one of the seventh to tenth means, the toner charge amount can be accurately determined by optically detecting the position in the height direction of the toner. Can be detected.
Further, in the developing device of the twelfth means, in addition to the effects of the eleventh means, the charge amount of the black toner can be detected by detecting the position in the height direction of the toner by the transmitted light.
Further, in the developing device of the thirteenth means, in addition to the effects of the eleventh means, the charge amount of the color toner can be detected by detecting the position in the height direction of the toner by the diffused light.
Furthermore, in the developing device of the fourteenth means, in addition to the effects of the eleventh means, the toner charge amount is detected accurately by detecting the position in the height direction of the toner with both transmitted light and diffused light. can do.

In the image forming apparatus of the fifteenth means, since the developing device of any one of the first to fourteenth means is provided as means for developing the latent image on the latent image carrier, the first to fourteenth means are provided. The effect of any one of the means can be obtained, and stable and good image formation can be performed.
In the image forming apparatus of the sixteenth means, in addition to the effect of the fifteenth means, an image obtained by superimposing a plurality of toner images formed on the latent image carrier is formed on the recording material. Stable and good multicolor or color image can be formed.

  In the process cartridge of the seventeenth means, at least one of the latent image carrier, the charging means, and the cleaning means and the developing device of any one of the first to fourteenth means are held together, so that the process cartridge is stable. A process cartridge capable of performing good image formation can be provided. Further, since the process cartridge is detachably attached to the image forming apparatus, the process cartridge can be easily replaced or recycled, which contributes to improvement of maintainability of the image forming apparatus and resource saving. it can.

  The image forming apparatus of the eighteenth means is provided with a plurality of process cartridges of the seventeenth means and can form a single color, multicolor or full color image to form a stable good single color, multicolor or color image. it can. In addition, since the plurality of process cartridges are detachably provided, they can be easily replaced or recycled, which contributes to improvement in maintainability of the image forming apparatus and resource saving. In addition, maintenance and management of the image forming apparatus are facilitated.

  Hereinafter, specific embodiments of a developing device, a process cartridge, and an image forming apparatus according to the present invention will be described in detail with reference to the drawings.

[Example 1]
An example of the electrode configuration of the toner carrier used in the developing device of the present invention is shown in FIG. 1, the toner carrier 21 has two phases. The odd-numbered electrodes 1a, 2a, 3a, 4a, 5a,... Are a-phase, the even-numbered electrodes 1b, 2b, 3b, 4b,. · Is b phase. FIG. 2 shows an example of voltages applied to the a-phase and b-phase electrodes of the toner carrier. The voltage is a rectangular wave, Vpp is 200 V to 1000 V, the frequency f is 0.5 to 5 kHz, and the central value V0 of the voltage varies between the image portion potential and the non-image portion potential depending on the development conditions. The a-phase and b-phase voltages are applied with a phase shift of π. Due to this phase difference, there is always a potential difference of Vpp between the a phase and the b phase. This electric potential difference Vpp generates an electric field between the electrodes, and the toner hops between the electrodes in accordance with the electric field. In FIG. 2, the voltage to be applied is a rectangular wave. However, in the case of a rectangular wave, voltage switching occurs instantaneously and is suitable for toner hopping, but it may be a sine wave or a triangular wave. FIG. 3 shows a view seen from a direction parallel to the axis of the toner carrier. In FIG. 3, the a-phase electrode is from the left side and the b-phase electrode is from the right side, and the a-phase and b-phase electrodes have a comb-like electrode configuration. The end of the toner carrying member 21 is a solid electrode, and wiring is performed from here to supply a voltage. As a method for producing the toner carrier 21, a resin is coated on a metal roller such as stainless steel serving as a shaft, or a metal roller is press-fitted into the resin roller, and electrodes are formed in a comb-teeth shape on the surface of the resin roller. Further, after the electrode is formed, the surface of the electrode is coated with an insulating layer to complete a toner carrier.

  FIG. 4 is a schematic configuration diagram of the developing device according to the first embodiment of the present invention. The developing device 20 in FIG. 4 is an example using a two-component developer composed of a magnetic carrier and a non-magnetic toner. 4 is divided into two chambers 24a and 24b, which are connected by developer passages (not shown) at both ends in the developing device. Two-component developers are accommodated in the developer accommodating portions 24a and 24b, and are conveyed through the developer accommodating portions while being agitated by the agitating and conveying screws 25a and 25b in the respective chambers. A toner replenishing port 26 is disposed in the developing device 20, and toner is replenished to the developer accommodating portion 24 a through a toner replenishing port from a toner accommodating portion (not shown). A toner concentration sensor (not shown) for detecting the magnetic permeability of the developer is installed in the developer container (24a or 24b), and detects the concentration of the developer. When the toner concentration in the developer accommodating portion (24a or 24b) decreases, the toner is replenished from the toner replenishing port 26 to the developer accommodating portion.

  A toner supply member (developer carrier) 22 is disposed at a position facing the agitating and conveying screw 25b. A fixed magnet is disposed inside the toner supply member 22, and the developer in the developer accommodating portion is pumped up to the surface of the toner supply member by the rotation and magnetic force of the toner supply member 22. A developer layer regulating member 23 is provided at a position facing the toner supply member 22 upstream of the developer pumping position in the rotation direction of the toner supply member 22. The developer pumped up at the pumping position is regulated to a certain amount of developer layer thickness by the developer layer regulating member 23. The developer that has passed through the developer layer regulating member 23 is conveyed to a position facing the toner carrier 21 having the above-described electrode configuration as the toner supply member 22 rotates.

  A supply bias is applied to the toner supply member 22 by the first voltage application means 27. This supply bias may be a DC voltage or an AC voltage. Alternatively, a bias in which an AC voltage is superimposed on a DC voltage may be used. At a position facing the toner carrier 21, an electric field is generated between the toner carrier 21 and the toner supply member 22 by the first and second voltage applying means 27 and 28. Under the electrostatic force from the electric field, the toner dissociates from the carrier and moves to the surface of the toner carrier 21. A voltage is applied to the electrode of the toner carrier 21 by the second voltage applying means 28. The voltage applied by the second voltage applying means 28 is most suitably a rectangular wave as shown in FIG. 2, but it may be a sine wave or a triangular wave.

  In this embodiment, as described above, the electrodes have two phases of the a phase and the b phase, and a voltage having a phase difference π is applied to each adjacent electrode to generate an electric field between the electrodes. The toner reaching the surface of the toner carrier 21 reciprocates between the electrodes while hopping by the electric field between the electrodes. In this embodiment, the toner is conveyed by the rotation of the toner carrier 21. The toner is conveyed to the development area by the rotation of the toner carrier 21 while reciprocating between the electrodes while hopping. The toner conveyed to the development area is developed on the latent image carrier 10 by a developing electric field between the toner carrier 21 and the image portion on the latent image carrier 10. The toner that has not contributed to the development is further conveyed by the rotation of the toner carrier 21 while hopping, and is collected from the surface of the toner carrier by a collecting means (not shown). The collected toner is returned again to the developer accommodating portions 24a and 24b and circulates in the developing device.

[Example 2]
Next, FIG. 5 is a schematic configuration diagram of a developing device showing a second embodiment of the present invention, and shows an example of a developing device 30 using a one-component developer made of a non-magnetic toner. The toner is accommodated in the developer accommodating portion 34 and is agitated by toner replenishing rollers 35a and 35b. Then, the toner is frictionally charged with the toner supply member 32 by the toner supply roller 35b, and is pumped up onto the toner supply member 32 by electrostatic force. The toner on the toner supply member 32 is made into a thin layer by the developer layer regulating member 33 and is conveyed to a position facing the toner carrier 31 having the above-described electrode configuration as the toner supply member 32 rotates.

  A supply bias is applied to the toner supply member 32 by a first voltage application unit 37. This supply bias may be a DC voltage or an AC voltage. Alternatively, a bias in which an AC voltage is superimposed on a DC voltage may be used. At a position facing the toner carrier 32, an electric field is generated between the toner carrier 31 and the toner supply member 32 by the first and second voltage applying means 37 and 38. Under the electrostatic force from the electric field, the toner dissociates from the toner supply member 32 and moves to the surface of the toner carrier 31. A voltage is applied to the electrode of the toner carrier 31 by the second voltage applying means 38. The voltage applied by the second voltage applying means 38 is most suitably a rectangular wave as shown in FIG. 2, but it may be a sine wave or a triangular wave.

  In this embodiment, as described above, the electrodes have two phases of the a phase and the b phase, and a voltage having a phase difference π is applied to each adjacent electrode to generate an electric field between the electrodes. The toner that has reached the surface of the toner carrier 31 reciprocates between the electrodes while hopping by the electric field between the electrodes. In this embodiment, the toner is conveyed by the rotation of the toner carrier 31. The toner is conveyed to the developing region by the rotation of the toner carrier 31 while reciprocating between the electrodes while hopping. The toner conveyed to the development area is developed on the latent image carrier 10 by a developing electric field between the toner carrier 31 and the image portion on the latent image carrier 10. The toner that has not contributed to the development is further conveyed by the rotation of the toner carrier, and is collected from the surface of the toner carrier by a collecting means (not shown). The collected toner is returned again to the developer container 34 and circulates in the developing device.

[Example 3]
Next, FIG. 6 is a schematic configuration diagram of a developing device showing a third embodiment of the present invention, which is an example of a developing device 40 having a configuration in which a toner collecting means is provided on the downstream side of the developing region in the toner transport direction. In FIG. 6, reference numeral 41 denotes a toner carrier, 42 denotes a toner supply member (or developer carrier), and 43 denotes a developer layer regulating member, which have the same configuration as the developing device of FIG. 4 or FIG. It is a member and the operation is the same. Reference numerals 45a and 45b are stirring and conveying members.

  Various methods are conceivable as the toner collecting means. FIG. 6 is a diagram illustrating toner collection by the collection plate 46 and the vibrator 47. A DC voltage is applied between the toner carrier 41 and the recovery plate 46 by the voltage applying means 48 to generate an electric field so that a force acts on the toner in a direction from the toner carrier 41 to the recovery plate 46. The toner that has not contributed to development in the development region moves from the toner carrier 41 to the recovery plate 46 in the recovery region where the recovery plate 46 and the toner carrier 41 face each other. When a certain amount of toner accumulates on the recovery plate, the recovery plate 46 is vibrated by the vibrator 47, the toner on the recovery plate is shaken off, and returned to the developer accommodating portion 44 again.

[Example 4]
Next, FIG. 7 is a schematic configuration diagram of a developing device showing a fourth embodiment of the present invention, which is another example of a developing device having a toner collecting means on the downstream side of the developing region in the toner transport direction. . In the developing device 40 shown in FIG. 7, toner is collected using a collection roller 49 as a toner collection unit. A DC voltage is applied between the toner carrier 41 and the collection roller 49 by the voltage application means 48 to generate an electric field so that a force acts on the toner in a direction from the toner carrier 41 to the collection roller 49. Toner that has not contributed to development in the development area moves from the toner carrier 41 to the collection roller 49 in the collection area where the collection roller 49 and the toner carrier 41 face each other. The toner adhering to the collecting roller 49 is scraped off by the blade 50 and is returned to the developer accommodating portion 44 again.

[Example 5]
Next, FIG. 8 is a schematic configuration diagram of a developing device showing a fifth embodiment of the present invention, which is still another example of a developing device having a toner collecting means on the downstream side of the developing region in the toner transport direction. is there. In the developing device 40 shown in FIG. 8, toner is collected using a brush roller 51 as toner collecting means. A DC voltage is applied between the toner carrier 41 and the brush roller 51 by the voltage applying means 48 to generate an electric field so that a force acts on the toner in a direction from the toner carrier 41 to the brush roller 51. Toner that has not contributed to development in the development area moves from the toner carrier 41 to the brush roller 51 in the collection area where the brush roller 51 and the toner carrier 41 face each other. The toner adhering to the brush roller 51 is scraped off by the flip cover 52 and returned again to the developer accommodating portion 44.

[Example 6]
Next, FIG. 9 is a schematic configuration diagram of a developing device showing a sixth embodiment of the present invention, which is still another example of a developing device having a toner collecting means on the downstream side of the developing region in the toner transport direction. is there. In the developing device 40 shown in FIG. 9, the toner is collected using the suction nozzle 53 as the toner collecting means. Specifically, the suction nozzle 53 and the toner carrier 41 are opposed to each other, and air is sucked from the suction nozzle 53 by the suction pump 55. A seal 54 is attached to the downstream side of the suction nozzle 53 in the toner conveyance direction, and this seal 54 is in contact with the surface of the toner carrier 41. The toner that has not contributed to development in the development area is collected through the suction nozzle 53 along the air flow in the collection area. The toner that is not carried by the air flow and is conveyed by the traveling wave electric field also collides with the seal 54 and is not conveyed downstream as it is. The toner collected by the suction nozzle 53 is returned to the developer accommodating portion 44 through the duct 56 again.

[Example 7]
Next, FIG. 10 is a schematic block diagram of a developing device showing a seventh embodiment of the present invention. The developing device 60 uses a one-component non-magnetic toner as a developer, and supplies toner directly from a toner supply roller 62, which is a toner supply member, to the toner carrier 61. The configuration of the toner carrier 61 is the same as that of the first embodiment.

  In the developing device 60 shown in FIG. 10, a sponge roller is used as the toner replenishing roller 62, and the sponge roller 62 is brought into contact with the toner carrier 61 to supply the toner onto the toner carrier while being charged. A supply bias is applied to the sponge roller 62 by the first voltage applying means 64, and the amount of toner supplied to the toner carrier 61 can be controlled by this voltage. This supply bias may be a DC voltage or an AC voltage. Alternatively, a bias in which an AC voltage is superimposed on a DC voltage may be used. A voltage is applied to the electrode of the toner carrier 61 by the second voltage applying means 65. The voltage applied by the second voltage applying means 65 is most suitably a rectangular wave as shown in FIG. 2, but it may be a sine wave or a triangular wave.

  In this embodiment, as described above, the electrodes have two phases of the a phase and the b phase, and a voltage having a phase difference π is applied to each adjacent electrode to generate an electric field between the electrodes. The toner supplied to the toner carrier 61 reciprocates between the electrodes while hopping by the electric field between the electrodes. In this embodiment, the toner is conveyed by the rotation of the toner carrier 61. The toner supplied from the toner supply roller 62 to the toner carrier 61 is further charged by the toner layer regulating member 63, and the amount of toner is regulated. The toner charged and regulated by the toner layer regulating member 63 is further transported to the development area by the rotation of the toner carrier 61 while hopping. The toner conveyed to the development area is developed on the latent image carrier 10 by a developing electric field between the toner carrier 61 and the image portion on the latent image carrier 10. The toner that has not contributed to the development is further conveyed by the rotation of the toner carrier 61 and reaches the toner supply roller 62 that is a toner supply member. The toner replenishing roller 62 sweeps away the toner that has not been used for development from the toner carrier 61 and returns the toner to the developer container 66.

[Example 8]
Next, an embodiment common to the developing devices (20, 30, 40, 60) of Embodiments 1 to 7 described above will be described.
In the developing devices (20, 30, 40, 60) of the first to seventh embodiments, the developing region is a region where the latent image carrier 10 and the toner carrier (21, 31, 41, 61) face each other. With the carrier 10 stopped, the image portion potential is opposed to the toner carrier (21, 31, 41, 61), and the toner is conveyed by the rotation of the toner carrier (21, 31, 41, 61). An area where toner is developed on the latent image carrier 10 is defined as a development area.
Further, in each embodiment, the supply region refers to the toner supply member (22, 32, 42, 62) in a state where the rotation of the toner carrier (21, 31, 41, 61) is stopped and no pulse voltage is applied to each electrode. The area where the toner is supplied onto the toner carrier is defined as the supply area.
Further, in each embodiment, the restriction region refers to a contact between the toner carrier and the developer layer restriction member (or toner layer restriction member) (23, 33, 43, 63) in a state where there is no toner on the toner carrier. An area is defined as a restricted area.

  In the configurations of the developing devices (20, 30, 40, 60) of the first to seventh embodiments, toner is transferred from the toner supply member (22, 32, 42, 62) onto the toner carrier (21, 31, 41, 61). When supplied, the toner has a certain amount of charge. Toner having a certain amount of charge is conveyed to the development area by the rotation of the toner carrier (21, 31, 41, 61) while repeating hopping by the electric field between the electrodes. Charge exchange occurs due to contact friction. Whether the toner charge amount increases or decreases due to contact friction between the toner and the toner carrier is determined by the frictional charging characteristics between the toner and the surface of the toner carrier, and the toner is hopped on the toner carrier for a long time. As a result, the toner charge amount converges to a certain value. The toner is transported to the development area while hopping on the toner carrier, but due to repeated contact friction due to hopping, the charge amount of the toner when entering the development area differs from the charge amount in the supply area and the regulation area. come. The amount of change in the charge amount is proportional to the number of contact frictions. The number of contact friction is considered to be proportional to the number of toner hops. The number of hoppings is considered to be proportional to the number of switching of the voltage applied to each electrode in the toner carrier. Therefore, by controlling the number of times the voltage applied to each electrode in the toner carrying body is controlled, the charge amount of the toner when entering the developing region can be controlled (first means).

  Therefore, the developing device of the present invention is provided with a switching number control means for controlling the number of times the applied voltage is switched before each electrode moves from the supply area to the developing area (second means). This is the case of the developing devices (20, 30) configured as shown in FIGS. 4 and 5 described in the first and second embodiments. In the case of the developing device having the configuration as shown in FIG. 10 described in the seventh embodiment, the switching number control means until each electrode moves from the restriction region where the toner carrier 61 and the toner layer restriction member 63 face each other to the development region. The number of times that the voltage applied to is switched is controlled (third means). The switching number control means controls the frequency of the pulse voltage applied to each electrode (fourth means). When the linear velocity of the toner carrier is constant, the time during which the toner is conveyed from the supply area or the regulation area to the development area is constant, so the number of times of switching is controlled by controlling the frequency of the pulse voltage applied to each electrode. Can be controlled. In addition, the number of times of switching can be controlled by controlling the linear velocity of the toner carrier (fifth means). In this case, since the frequency of the pulse voltage is constant, when the linear velocity is increased, the development area is reached in a short time, and the number of switching is reduced. If the linear velocity is reduced, the time to reach the development area becomes longer and the number of times of switching increases. It is also possible to control by combining both the frequency of the pulse voltage and the linear velocity of the toner carrier (sixth means). In the developing device of the present invention, the toner charge amount when entering the development region is -10 μC / g to −40 μC / g for a toner having a particle diameter of 5 μm to 6 μm, and the toner charge amount is in the meantime. Is controlling. When the absolute value of the charge amount is larger than 40, the absolute value of the charge amount is made 40 or less by decreasing the number of times of switching. When the absolute value of the charge amount is less than 10, the charge amount of the charge amount is increased by increasing the number of times of switching. The absolute value is controlled to 10 or more.

In order to control the charge amount of the toner on the toner carrier, it is necessary to know the charge amount of the toner on the toner carrier. Therefore, in the present invention, charge amount detection means for detecting the charge amount of the toner on the toner carrier is provided (seventh means).
For example, as shown in FIG. 11, the charge amount detecting means 73 is a toner supply member with respect to the rotation direction of the toner carrier 71 (corresponding to any one of 21, 31, 41, and 61 in Examples 1 to 7). 72 (corresponding to any one of 22, 32, 42, and 62 in Examples 1 to 7) downstream from the supply region and upstream from the development region, or as shown in FIG. 12, a developer layer A regulating member (or toner layer regulating member) 74 (corresponding to any of 23, 33, 43, and 63 in Examples 1 to 7) is provided downstream from the regulating region and upstream from the developing region (eighth). Means). As a result, the charge amount of the toner entering the development area can be detected by the charge amount detection means 73.
In the present invention, based on the charge amount of the toner detected by the charge amount detection means 73, the switching number control means controls the number of times the voltage of the electrode is switched, thereby controlling the charge amount of the toner on the toner carrier. (9th means).

  The toner receives a force from the electric field between the electrodes and hops on the toner carrier, but the force received by the toner is proportional to the charge amount of the toner and the electric field strength. When the pulse voltage applied to the electrode of the toner carrier is constant, the force received by the toner is proportional to the charge amount of the toner. When the charge amount of the toner is large, the toner receives a large force and can be hopped higher, and the average toner position on the toner carrier becomes high. On the contrary, when the charge amount of the toner is small, the force received by the toner is small and the toner cannot be hopped so much. Therefore, if the hopping height of the toner on the toner carrier is known, the charge amount of the toner can be known. The charge amount detection means 73 used in the developing device of the present invention detects the position in the height direction of the toner on the toner carrier (tenth means). More specifically, the hopping height of the toner is optically detected using a light emitting element and a light receiving element (eleventh means). And by detecting optically, it is possible to detect without affecting the electric field strength and the toner movement.

  There are two possible configurations for optical detection using a light emitting element and a light receiving element for the charge amount detecting means 73. One is a configuration in which a light emitting element 73A is disposed at one of both ends of the toner carrier 71 and a light receiving element 73B is disposed at the other, as shown in FIG. In this configuration, the light in the height region where the toner is hopping on the toner carrier 71 is absorbed or scattered by the toner and cannot reach the light receiving element 73B. However, light at a position higher than the height region where the toner is hopping can reach the light receiving element 73B without being scattered by the toner. Therefore, the hopping height of the toner can be detected by detecting the transmitted light out of the light from the light emitting element 73A (the twelfth means). In particular, since black toner absorbs light, a detection method having such a configuration is suitable.

  Another configuration is a configuration in which both the light emitting element 73A and the light receiving element 73B are arranged at one end of the toner carrier 71 as shown in FIG. In the case of this configuration, the light in the height region where the toner is hopping on the toner carrier 71 is scattered by the toner. Therefore, the hopping height of the toner can be detected by detecting the diffused light by the light receiving element 73B. (13th means). In particular, since color toner diffuses light, a detection method having such a configuration is suitable. Further, by detecting these two components in combination, the toner hopping height can be detected with high precision (fourteenth means).

  FIG. 15 is a flowchart showing the flow of toner charge amount detection and control. This control is performed by a control unit of an image forming apparatus (not shown) (a central processing unit (CPU) composed of a microcomputer, a recording device storing various control programs and data (a variety of memories such as ROM, RAM, and nonvolatile RAM, a hard disk, (Various card memories, etc.), input / output interface, clock, timer, various control circuits, etc.).

  In FIG. 15, first, the toner carrier 71 and the toner supply member 72 are rotated before supplying the toner (S1). Next, a pulse voltage is applied to the electrode of the toner carrier 71 (S2). Then, a voltage is applied to the toner supply member 72. The toner thus supplied is conveyed by the rotation of the toner carrier 71 while hopping by the electric field between the electrodes (S3). Next, the hopping height of the toner on the toner carrier is optically detected using the light emitting element 73A and the light receiving element 73B of the charge amount detecting means 73 (S4). From the detection result, the toner charge amount q / m is determined (S5). It should be noted that the amount of charge from the hopping height is obtained in advance through experiments or the like, and the results of these experiments are collected in a data table or the like and recorded in the recording device of the control unit in the image forming apparatus. .

  Based on the detected hopping height, the CPU of the control unit reads the data table of the recording apparatus and determines the corresponding charge amount. When the charge amount is determined, the charge amount is compared with the standard charge amount (S6). If the difference between the standard charge amount and the determined charge amount | (standard q / m) −q / m | is smaller than the threshold value (q / m) th, the charge amount at that time is regarded as normal, End. In addition, when the difference | (standard q / m) −q / m | between the standard charge amount and the determined charge amount is larger than the threshold value (q / m) th, the number of switching times is controlled by the switching number control means. I do.

Here, how much the number of times of switching should be changed depending on the value of the detected charge amount is determined in advance by an experiment or the like, compiled in a data table or the like, and recorded in a recording device of the control unit. Keep it. Then, the amount of charge is detected as described above, and when control of the number of switching is necessary, the CPU of the control unit goes to read the data table recorded in the recording device, determines the number of switching, The number of times of switching is changed (S7).
After changing the number of times of switching, the charge amount is detected again, and the control is repeated until the difference between the standard charge amount and the determined charge amount becomes smaller than the threshold value (S3 to S8).

  However, if the control is repeated a certain number of times (N times), it is considered that an abnormality has occurred, and the fact that there is an abnormality is displayed on the display unit of the image forming apparatus (S9). Furthermore, when the image forming apparatus has a communication unit that communicates information with an external central management apparatus or the like, abnormality information may be transmitted to the central management apparatus or the like. Note that the upper limit value N of the number of control repetitions may be a fixed value, or may be changed depending on the operation time of the image forming apparatus, the number of output sheets, and the like. Further, such detection and control of the charge amount on the toner carrier is performed at a certain timing. It may be performed when the image forming apparatus is turned on, or may be performed at a certain time interval after the power is turned on. Alternatively, it may be performed for each output number of images. Further, it may be performed by an input signal from the operation display unit of the image forming apparatus.

[Example 9]
Next, FIG. 16 is a schematic configuration diagram showing a configuration example of an image forming apparatus using the developing device described in the first to eighth embodiments, and shows an example of a digital copying machine (or a digital multifunction machine). Yes. The image forming apparatus includes an image forming unit (printer unit) 100 and an image reading unit (scanner unit) 110. The image forming unit (printer unit) 100 reads the image using the image reading unit (scanner unit) 110. Image formation is performed in accordance with image information of a document, image information input via a LAN from a personal computer or the like outside the apparatus, or image information transmitted from the outside via a communication line.

  A drum-shaped photoconductor 10 that is a latent image carrier is disposed in a substantially central portion of the image forming unit (printer unit) 100, and a charging device that is a charging unit that charges the photoconductor 10 around the photoconductor 10. (For example, a charging roller, a charging charger, a charging brush, etc.) 11 and an optical writing device that forms an electrostatic latent image by irradiating light to the charged photoreceptor in accordance with image information (for example, laser scanning optical writing) Or a developing device that develops the latent image on the photosensitive member with toner (FIG. 4 in the example shown in FIG. 4). A developing device 20), a transfer device (for example, a transfer roller, a transfer charger, a transfer brush, etc.) 13 for transferring a toner image formed on the photosensitive member to a recording material P, and residual toner on the photosensitive member after transfer. Cleaning device (for example, A cleaning blade, a cleaning brush, a cleaning roller or the like) 14, charge removing device (e.g., charge removing lamp for removing a residual charge on the photosensitive member, discharger, such as charge removal brush) 15 are disposed. In addition, a toner storage unit 29 is provided at the top of the developing device 20 so that toner is supplied from the toner storage unit 29 to the developer storage unit through the toner supply port.

  When image formation is started, an image forming operation by an electrophotographic process is executed, the photoconductor 10 rotates clockwise as indicated by an arrow in the figure, and the surface of the photoconductor is uniformly charged by the charging device 11. Then, the optical writing device 12 irradiates the charged photoconductor 10 with light according to image information to form an electrostatic latent image. This electrostatic latent image is developed with the toner carried on the toner carrier 21 of the developing device 20 and visualized as a toner image.

  A paper feed cassette 16 containing a recording material P such as recording paper is mounted below the image forming unit 100, and the recording material P in the paper feed cassette 16 is fed in time with the above image forming operation. The paper is fed one by one by the paper roller 17a and the separation roller 17b, and is conveyed to the registration roller 17d through a plurality of conveyance rollers 17c. Then, the recording material P is sent to the transfer position by the registration roller 17d in accordance with the timing when the toner image on the photoconductor reaches the transfer position, and the toner image on the photoconductor is transferred to the recording material P by the transfer device 13. The recording material P onto which the toner image has been transferred is conveyed to the fixing device 18 via the conveying belt 17e, and is heated and pressurized by the fixing device 18 to fix the toner image on the recording material P. The recording material P after fixing is discharged to the discharge tray 120 through a plurality of discharge rollers 19a to 19e. In addition, after the toner image is transferred, the residual toner is cleaned by the cleaning device 14 and the residual charge is discharged by the charge removal device 15.

[Example 10]
In the image forming apparatus as described in the above embodiment, a process cartridge in which at least one of a photosensitive member, a charging device, and a cleaning device and a developing device are integrated can be used.
FIG. 17 is a schematic cross-sectional view showing an example of a process cartridge. This process cartridge 80 includes a photosensitive member 10, a charging device 11, a developing device (developing device shown in FIG. 10 in the illustrated example) 60, and a cleaning device 14. 81 is integrally held. Since the process cartridge 80 is detachably attached to the image forming apparatus, the process cartridge 80 can be easily replaced or recycled, and contributes to improving the maintainability of the image forming apparatus and saving resources. Can do.

[Example 11]
Next, FIG. 18 is a schematic configuration diagram showing a configuration example of a color image forming apparatus which includes a plurality of process cartridges 80 shown in FIG. 17 and forms a single color, multicolor or full color image.
In this color image forming apparatus 200, four process cartridges 80Y, 80M, 80C, and 80K are juxtaposed along the transfer belt 90 that conveys the recording material P. The process cartridge 80Y has the same electronic components as in the ninth embodiment. A yellow toner image is formed on the photoconductor by the photographic process, and the process cartridge 80M forms a magenta toner image on the photoconductor by the same electrophotographic process as in the ninth embodiment. A magenta toner image is formed on the photoconductor by the same electrophotographic process as in the above, and the process cartridge 80K forms a black toner image on the photoconductor by the same electrophotographic process as in the ninth embodiment.

  Below the transfer belt 90, multi-stage paper feed cassettes 16A and 16B containing recording material P such as recording paper are mounted, and image forming operations are performed in the process cartridges 80Y, 80M, 80C, and 80K. At the same timing, the recording material P is fed from one of the paper feed cassettes 16A and 16B one by one by the paper feed roller 17a and the separation roller 17b, and is conveyed to the registration roller 17d via a plurality of conveyance rollers 17c. The recording material P is sent to the transfer belt 90 by the registration roller 17d in accordance with the timing when the toner images on the photosensitive members of the process cartridges 80Y, 80M, 80C, and 80K come to the transfer position, and the recording material is transferred by the transfer belt 90. Each of the process cartridges 80Y, 80M, 80C, and 80K is sequentially conveyed to the transfer position, and each color toner image on the photosensitive member is sequentially transferred onto the recording material P by each transfer device 13. The recording material P onto which the toner image has been transferred is conveyed to the fixing device 18 via the conveying belt 17e, and is heated and pressurized by the fixing device 18 to fix the toner image on the recording material P. The recording material P after fixing is discharged to a discharge tray 210 through a plurality of discharge rollers 19a to 19e. Further, the residual toner is cleaned by the cleaning device 14 in the photosensitive members 10 of the process cartridges 80Y, 80M, 80C, and 80K after the toner image is transferred.

  In the color image forming apparatus 200 having the above-described configuration, the process cartridges 80Y, 80M, 80C, and 80K are selectively driven to form a single color, multicolor, or full color image. Further, since each process cartridge 80Y, 80M, 80C, 80K is detachably attached to the image forming apparatus, it can be easily replaced or recycled, thereby improving the maintainability of the image forming apparatus and saving it. This contributes to resource recycling, and maintenance and management of the color image forming apparatus 200 are easy.

FIG. 18 shows a configuration example of a direct transfer tandem color image forming apparatus in which four process cartridges 80Y, 80M, 80C, and 80K are arranged in parallel along the transfer belt 90 that conveys the recording material P. However, if an intermediate transfer belt is used in place of the transfer belt 90 and a secondary transfer portion for secondary transfer from the intermediate transfer belt to the recording material is provided, an intermediate transfer tandem color image forming apparatus can be configured. .
FIG. 18 shows only the configuration of the printer unit. Similarly to FIG. 16, if an image reading unit (scanner unit) is installed on the upper part of the printer unit, a multifunction device that functions as a printer or a digital copying machine. Can be configured. Further, it can be used as a facsimile by connecting to a communication line.

FIG. 4 is a cross-sectional view of a main part showing an example of an electrode configuration of a toner carrier used in the developing device of the present invention. FIG. 2 is a diagram illustrating an example of voltages applied to a-phase and b-phase electrodes of the toner carrier illustrated in FIG. 1. FIG. 2 is a view of the toner carrier shown in FIG. 1 as viewed from a direction parallel to an axis. 1 is a schematic configuration diagram of a developing device showing a first embodiment of the present invention. It is a schematic block diagram of the developing device which shows the 2nd Example of this invention. It is a schematic block diagram of the developing device which shows the 3rd Example of this invention. It is a schematic block diagram of the developing device which shows the 4th Example of this invention. It is a schematic block diagram of the developing device which shows the 5th Example of this invention. It is a schematic block diagram of the developing device which shows the 6th Example of this invention. It is a schematic block diagram of the developing device which shows the 7th Example of this invention. FIG. 4 is a diagram illustrating an installation position of a charge amount detection unit that detects a charge amount of toner on a toner carrier. FIG. 4 is a diagram illustrating an installation position of a charge amount detection unit that detects a charge amount of toner on a toner carrier. It is a figure which shows the structural example in the case of detecting optically using a light emitting element and a light receiving element for a charge amount detection means. It is a figure which shows another structural example in the case of detecting optically using a light emitting element and a light receiving element for a charge amount detection means. 6 is a flowchart illustrating a flow of detection and control of a toner charge amount. 1 is a schematic configuration diagram illustrating a configuration example of an image forming apparatus using a developing device of the present invention. It is a schematic sectional drawing which shows an example of the process cartridge using the developing device of this invention. It is a schematic block diagram which shows the structural example of the color image forming apparatus provided with two or more process cartridges shown in FIG.

Explanation of symbols

1a, 2a, 3a, 4a, 5a: a phase electrode 1b, 2b, 3b, 4b: b phase electrode 10: photoconductor (latent image carrier)
DESCRIPTION OF SYMBOLS 11: Charging device 12: Optical writing device 13: Transfer device 14: Cleaning device 15: Static elimination device 16, 16A, 16B: Paper feed cassette 18: Fixing device 20, 30, 40, 60: Developing device 21, 31, 41 61, 71: Toner carrier 22, 32, 42, 62, 72: Toner supply member 23, 33, 43, 63: Developer layer regulating member (or toner layer regulating member)
24a, 24b, 34, 44, 66: developer accommodating portions 25a, 25b: stirring and conveying screws 27, 37, 64: first voltage applying means 28, 38, 65: second voltage applying means 35a, 35b: toner replenishing rollers 45a, 45b: Agitating and conveying member 73: Charge amount detecting means 73A: Light emitting element 73B: Light receiving element 80, 80Y, 80M, 80C, 80K: Process cartridge 90: Transfer belt 100: Image forming unit (printer unit)
110: Image reading unit (scanner unit)
120, 210: discharge tray 200: color image forming apparatus P: recording material

Claims (18)

In a developing device having a toner carrier that is disposed opposite to a latent image carrier and carries toner for developing an electrostatic latent image on the latent image carrier,
A plurality of electrodes arranged at a predetermined interval inside the toner carrier, and voltage applying means for applying a voltage to the electrodes so that an electric field between the plurality of electrodes changes with time, It is configured to form a cloud by causing the toner on the toner carrier to fly by an electric field between the electrodes, and includes toner charge amount control means for controlling the charge amount of the toner on the toner carrier. Developing device. The developing device according to claim 1,
A toner supply unit configured to supply toner to the toner carrier, and the toner supplied in a supply region where the toner supply unit and the toner carrier face each other is rotated by the rotation of the toner carrier; And the toner carrying member are conveyed to the opposite development area, and the toner charge amount control means determines the number of times the applied voltage is switched before each electrode moves from the supply area to the development area. A developing device characterized in that it is a switching frequency control means for controlling. The developing device according to claim 1,
A toner supply unit that supplies toner to the toner carrier, and a toner layer regulating member that regulates the toner supplied to the toner carrier by the toner supply unit, and the toner regulated by the toner layer regulating member is The latent image carrier and the toner carrier are transported to a development area facing each other by the rotation of the toner carrier, and the toner charge amount control means is configured such that each electrode includes the toner carrier and the toner layer. A developing device, comprising: a switching number control means for controlling the number of times that a voltage to be applied is switched before the regulating member moves from the regulating region facing the regulating member to the developing region. In the developing device according to claim 2 or 3,
The developing device characterized in that the switching frequency control means controls the frequency of the voltage applied by the voltage application means. In the developing device according to claim 2 or 3,
The developing device characterized in that the switching number control means controls the linear velocity of the toner carrier. In the developing device according to claim 2 or 3,
The developing device characterized in that the switching frequency control means controls both the frequency of the voltage applied by the voltage applying means and the linear velocity of the toner carrier. In the developing device according to any one of claims 1 to 6,
A developing device comprising charge amount detecting means for detecting a charge amount of toner on the toner carrier. The developing device according to claim 7,
2. A developing apparatus according to claim 1, wherein said charge amount detecting means is provided at a position downstream of said supply region or said restriction region and upstream of said developing region with respect to a rotation direction of said toner carrier. In the developing device according to any one of claims 1 to 8,
2. A developing device according to claim 1, wherein said switching number control means controls the number of electrode switching based on a detection result of said charge amount detecting means. The developing device according to any one of claims 7 to 9,
The developing device according to claim 1, wherein the charge amount detecting means detects a position of the toner on the toner carrier in a height direction from the surface of the toner carrier. In the developing device according to any one of claims 7 to 10,
The developing device according to claim 1, wherein the charge amount detecting means comprises a light emitting element and a light receiving element. The developing device according to claim 11, wherein
The developing device according to claim 1, wherein the light emitting element projects light onto a toner conveyance path conveyed by rotation on the toner carrier, and the light receiving element detects light transmitted without being scattered by the toner. The developing device according to claim 11, wherein
The developing device according to claim 1, wherein the light emitting element projects light onto a toner conveyance path conveyed by rotation on the toner carrier, and the light receiving element detects diffused light scattered by the toner. The developing device according to claim 11, wherein
The light emitting element projects light onto a toner conveyance path conveyed by rotation on the toner carrier, and the light receiving element emits both light that is transmitted without being scattered by the toner and diffused light that is scattered by the toner. A developing device characterized by detecting. In an image forming apparatus for developing a latent image by attaching toner to a latent image on a latent image carrier, and finally transferring the toner image obtained thereby to a recording material to form an image.
An image forming apparatus comprising the developing device according to claim 1 as means for developing a latent image on the latent image carrier. The image forming apparatus according to claim 15.
An image forming apparatus, wherein an image obtained by superimposing a plurality of toner images formed on the latent image carrier is formed on a recording material. A process cartridge installed in an image forming apparatus that forms an image by an electrophotographic process,
The at least one of a latent image carrier, a charging unit, and a cleaning unit and the developing device according to any one of claims 1 to 14 are integrally held, and are detachably provided to the image forming apparatus. A process cartridge characterized by that. An image forming apparatus that forms an image by an electrophotographic process,
An image forming apparatus comprising a plurality of the process cartridges according to claim 17 to form a single color, multicolor or full color image.

Images