JP2010033001A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously supply only a required amount of a developer having a proper toner density and a charge amount by efficiently mixing and stirring a toner and developer without applying an unnecessary stress and efficiently regulating a charge amount of the developer irrespective of a disturbance condition. <P>SOLUTION: The charge amount can be quickly regulated to a proper amount without applying unnecessary stress by regulating (reducing) the charge amount of the developer from a developing part by an ionized air flow, and enhancing dispersability of a replenishing toner. The developer carried upwards from a down side by a screw 43 forms a convection moved downwards by rotation of a stirring member 44, and collected again in the periphery of the screw 47. The whole developer stirring part 40 inside is uniformly mixed by this manner. The convection of the developer enhances the probability of contact, and reduces also a damage onto the developer. The toner charge amount can be led up uniformly to the proper value, when the charge amount is reduced before the stirring by the ionized air flow. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device using a two-component developer such as a copying machine and an image forming apparatus provided with the developing device.

  A developing device using a two-component developer is a device that develops and visualizes an electrostatic latent image formed on an image carrier (photoconductor, etc.) with toner using a two-component developer composed of toner and carrier. is there.

  In such an apparatus, the developer whose toner has been consumed after completing the development process in the development region is collected, mixed and stirred with the toner to be replenished, and is often used again for development. Therefore, the developer used in the developing device having such a configuration needs to maintain a constant toner concentration and charge amount in order to obtain a stable toner image. This is because the toner density is adjusted by the amount of toner consumed in development and the amount of replenished toner, and the charge amount is given by frictional charging during mixing of the carrier and toner. Therefore, in this type of developing device, the two-component developer composed of toner and carrier is sufficiently agitated to uniformize the toner concentration distribution, and to charge the toner to stabilize the toner image. .

  However, the charge amount of the toner varies depending on various factors, and the charge amount varies even under the same stirring condition. For example, the factors include the surrounding environment (temperature and humidity), the charging performance of the carrier over time, the change in the toner charge amount depending on the output image area, that is, the difference in the charge amount due to the toner residence time. Further, the amount of charge varies depending on the amount of toner newly supplied. This is because when the amount of toner is large, mixing and stirring takes time.

  Conventionally, in a general developing device of this type, the toner is dispersed and charged by using the stirring effect of the rotation of two screws during a short time until the replenished toner is pumped up to the developing sleeve. Therefore, particularly when the toner balance is large, the replenished toner does not sufficiently disperse and is drawn up to the developing sleeve, causing quality problems such as background contamination and toner scattering.

  In order to prevent such toner scattering and image defects due to insufficient mixing and stirring, a device in which a large number of mixing and stirring members are provided in the developing device to improve mixing and stirring properties has been proposed. However, on the other hand, the developer agitation stress is increased and the charging ability is lowered due to the deterioration of the developer over time.As a result, the charge amount is not stable, and there are problems such as toner scattering and background stains over time. It is left. When stress is applied to the developer, the charging ability is lowered due to the scraping of the coat film of the carrier, the charging ability is lowered due to the degree of toner additive burying, and the fluidity is changed. A change in fluidity also causes a decrease in image quality due to a change in charging ability and a change in transfer rate.

  In order to solve these problems, in Patent Document 1, a stirrer is separately provided at a location distant from the developing unit, the developing unit and the stirrer are connected by a circulation means, and stirring according to the state of the developer is performed by the stirrer. There has been proposed a developing device that supplies a developer with a toner density and a charge amount appropriately adjusted to a developing unit. The stirring unit of Patent Document 1 has the configuration shown in FIG. 14 of the same document, and stirring is performed by rotating a rotating shaft provided with a plurality of stirring members. Such a stirring method is widely used, but the stirring operation tends to be united, and it takes time to stir the entire container. Therefore, it is necessary to enlarge the stirring part, increase the amount of staying developer, and keep the stirring part for a long time. Further, if the rotational speed of stirring is increased in order to stir in a short time, there is a concern about damage to the developer.

  The present invention has been made in view of such a conventional technique. The replenished toner and the developer are efficiently mixed in a short time without being subjected to extra stress, and the charge amount of the developer is disturbed. Regardless of conditions (use conditions), a developing device and an image that can be adjusted efficiently and can continuously supply a developer having an appropriate toner concentration and charge amount to the developing unit in an amount necessary for development. An object is to provide a forming apparatus.

  The developing device according to claim 1 of the present invention is a developing device using a two-component developer composed of a toner and a carrier, and includes a developing unit and a developer stirring unit as separate units, and an ionization unit. In a developing device that includes an air flow generating means and in which the developer circulates between the developing unit and the developer agitating unit, introduction of an ionized air flow for adjusting the charge amount of the toner and the carrier in a path through which the developer circulates It is characterized by comprising a mouth.

  According to a second aspect of the present invention, in the developing device according to the first aspect, an ionization airflow inlet is provided in a discharge path from the developing unit to the developer stirring unit.

  According to a third aspect of the present invention, in the developing device according to the first aspect, an ionized airflow inlet is provided in a supply path from the developer stirring section to the developing section.

  According to a fourth aspect of the present invention, in the developing device according to the first aspect, the developer stirring section is provided with an inlet for ionized airflow.

According to the fifth aspect of the present invention, in the developing device according to any one of the first to fourth aspects, the operation of the ionized airflow generating means can be arbitrarily turned on / off, and the ion balance of positive ions and negative ions can be adjusted. It can be arbitrarily controlled.

  According to Claim 6, in the developing device according to any one of Claims 1 to 5, at least a mesh, a porous plate, or a function equivalent to them cannot be passed through the introduction port of the ionized airflow. It is characterized by arranging means.

  According to the seventh aspect of the present invention, in the developing device according to any one of the first to sixth aspects, an ionized air flow is introduced from a direction opposite to the developer circulation direction during the circulation of the developer. And

  According to the eighth aspect of the present invention, in the developing device according to any one of the first to seventh aspects, the toner replenishing port is disposed in a discharge path from the developing unit to the developer stirring unit, and the ionized airflow is generated. It is characterized by being provided on the upstream side in the toner transport direction with respect to the inlet.

  According to a ninth aspect of the present invention, in the developing device according to any one of the first to eighth aspects, the number of rotations of the stirring member of the developer stirring unit can be arbitrarily controlled.

  According to a tenth aspect of the present invention, in the developing device according to any one of the first to ninth aspects, the means for circulating the developer is air conveyance by the ionized airflow.

  According to an eleventh aspect of the present invention, in the developing device according to any one of the first to tenth aspects, the adjustment of the charge amount of the toner and the carrier is a reduction of the charge amount.

  According to a twelfth aspect of the present invention, in the developing device according to the second aspect, the ionized airflow generating means is provided above the discharge path through the ionized airflow inlet, and the ionized airflow generating means is provided in a case. And a wire member that is disposed inside the case and to which a bias voltage is applied between the case and an air current that is supplied into the case from ions generated due to discharge caused by the application of the bias voltage. The ionized airflow is introduced into the discharge path from the ionization airflow inlet.

  According to a thirteenth aspect of the present invention, there is provided a developing roller for carrying and conveying a developer, a first conveying screw for supplying the developer to the developing roller while conveying the developer in the longitudinal direction, and the first conveying screw. A developing device including a second conveying screw that conveys the developer in a direction opposite to the developer conveying direction, a toner replenishing port that replenishes toner upstream of the second conveying screw in the developer conveying direction, The developing device is characterized in that an ionized air flow introduction port for introducing an ionized air flow is disposed downstream of the toner supply port in the developer conveyance direction and below the second conveyance screw.

  According to a fourteenth aspect of the present invention, there is provided an image forming apparatus comprising the developing device according to any one of the first to fourteenth aspects.

  According to the present invention, the replenished toner and the developer can be efficiently mixed in a short time, mixed and agitated without applying extra stress, and the charge amount of the developer can be adjusted efficiently regardless of use conditions such as disturbance. In addition, a developer having an appropriate toner concentration and charge amount can be continuously supplied to the developing portion in an amount necessary for development.

1 is a diagram illustrating an overall configuration of an example of an image forming apparatus that is an object of the present invention. The perspective view which shows the structure of the image development part of the Example of this invention, a developing agent stirring part, a rotary feeder part, and an air pump in detail. Diagram showing the internal configuration of the development unit Configuration diagram of ionizer, which is a means for generating ionized airflow Sectional view of a state where an ionized air flow inlet is provided in the developer discharge flow path from the developing section to the developer stirring section, and the ionized air flow from the ionizer is sent to the developer discharge flow path through the flow path Schematic diagram of the mechanism of FIG. The figure which shows the cross section and detail of a developer stirring part and a rotary feeder part The perspective view which shows the 2nd Example of this invention. Sectional drawing which shows the 3rd Example of this invention Sectional drawing which shows the 4th Example of this invention Sectional drawing which shows the 5th Example of this invention The figure which shows the pre mixing part used for the 5th Example of this invention. The perspective view which shows the structure of the image development part of a 5th Example of this invention, a developer stirring part, a rotary feeder part, and an air pump in detail. Sectional drawing which shows the modification of the 5th Example of this invention Sectional drawing which shows the 6th Example of this invention Diagram showing an example of charge amount control using ionized airflow The figure which shows the state which the cylindrical container rotates in a cylindrical-axis direction, and the developer (toner and carrier) inside a container is stirred by the rotational motion and the magnetic force from the container side surface. Sectional drawing which shows the 7th Example of this invention Schematic diagram showing the eighth embodiment of the present invention.

  The present invention is an apparatus using a two-component developer composed of a toner and a carrier, and includes a developing unit and a developer stirring unit as separate units, and further includes an ionized airflow generating unit, and the developing unit and the developer The developing device in which the developer circulates in the agitation unit is configured to include an ionized air flow inlet for adjusting the charge amount of the toner and the carrier in the path through which the developer circulates. In addition, the ionization airflow inlet is provided in the developer agitating section in the discharge path from the developing section to the developer agitating section and in the supply path from the developer agitating section to the developing section. The operation of the ionized airflow generating means can be arbitrarily turned on / off, and the ion balance between positive ions and negative ions can be arbitrarily controlled. It is assumed that a plate plate or a means having the same function as those is provided and an ionized air flow is introduced from a direction opposite to the developer circulation direction.

  FIG. 1 is a diagram showing an overall configuration of an example of an image forming apparatus that is an object of the present invention. This apparatus is a color image forming apparatus. In the drawing, reference numeral 81 denotes an apparatus main body, and an image forming unit corresponding to four colors of yellow, magenta, cyan, and black is disposed below the intermediate transfer belt 85. The configuration of each color image forming unit is the same, and includes the photoconductor 1, the charging unit 82, the developing unit 2, the primary transfer unit 84, the cleaning unit 83, and the like.

  In operation, first, the photosensitive member 1 is uniformly charged by the charging unit 82, and then an electrostatic latent image corresponding to the image to be created is formed on the surface of the photosensitive member 1 by an optical writing unit (not shown). The latent image is developed by the unit 2 and a toner image is formed on the photoreceptor 1. The toner images of the respective colors formed by the respective image forming units in this way are sequentially transferred onto the surface of the intermediate transfer belt 85 by the primary transfer unit 84. As a result, a full-color toner image is formed on the intermediate transfer belt 85. The full-color toner image is transferred to the transfer paper supplied from the paper feed cassette 87 by the secondary transfer unit 88, and then passes through the fixing unit 89, so that the toner is released by heat and the color image is fixed on the transfer paper. The Reference numeral 90 denotes a paper discharge unit for discharging the created image. In the figure, 91 is an air suction port, 92 is an external air suction path, 93 is a dehumidifier, and 94 is an air intake port.

  In the configuration of the present invention, the developing unit 2 is characterized, and the developer (mixture of toner and carrier) usually used for development is only stirred and mixed in the developing unit. The developer agitating unit 40 is provided at a location apart from the developing unit 2, and the developer agitating unit 40 reliably agitates the developer and more stably charges the toner than before, thereby stabilizing the image. Allows formation to be performed.

  The operation will be described. The developer that has been developed in the developing unit 2 is discharged from the developing unit 2 through the developer discharge channel 3 and sent to the developer stirring unit 40. Next, in the developer agitating unit 40, new toner is replenished and sufficiently agitated by an agitating fin (not shown), and then discharged in a fixed amount by a rotary feeder (not shown). The discharged developer is transported by the pressure of the air sent by the air pump 60 and returned to the developing unit 2 through the developer supply channel 4. Replenishment of new toner is performed by discharging the toner from the toner hopper 30 little by little.

  FIG. 2 is a perspective view showing in detail the configuration of the developing unit 2, the developer stirring unit 40, the rotary feeder unit, and the air pump according to the embodiment of the present invention. In the figure, reference numeral 1 denotes a photosensitive drum, and an electrostatic latent image is formed on the surface by a charger and an optical writing device (not shown). Reference numeral 2 denotes a developing unit (the internal configuration is shown in FIG. 3). Reference numeral 40 denotes the entire developer stirring unit. The developer discharged from the developer discharge section of the developing section 2 falls in the developer discharge flow path 3 by its own weight and is put into the developer stirring section 40.

  In the developer stirring section 40, the shaft provided with the stirring member 44 is rotationally driven by a stirring motor 45 through a gear 46. Further, new toner is supplied to the developer stirring unit 40 from the toner hopper 30 as the toner is consumed. The toner is replenished by the drive motor 32 through the toner supply path 31. As shown in FIG. 2B, a small conveying screw (auger) 35 is disposed in the toner supply path 31 so that a certain amount of toner can be conveyed. In the figure, reference numeral 41 denotes a toner outlet opening to a rotary feeder 50 described later.

  The rotary feeder 50 functions to discharge a constant amount of developer stirred by rotating an internal impeller. In the figure, reference numeral 55 denotes a rotary feeder driving motor.

  The developer that is quantitatively discharged from the rotary feeder 50 is transported by the air inside the developer supply channel 4 by the air pressure supplied from the air pump 60 and returned to the developer charging unit 5 of the developing unit. In the figure, 99 is an ionizer, and 103 is an ionized air flow inlet.

  FIG. 3 is a diagram showing an internal configuration of the developing unit 2. In the figure, reference numeral 20 denotes a developing roller, which has a magnet disposed therein and serves to attract and convey the developer to adhere toner to the electrostatic latent image on the surface of the photoreceptor 1. In the figure, reference numerals 21 and 22 denote conveying screws, and the conveying screw 21 indicates the developer supplied from the developer charging unit 5 provided in the center position in the longitudinal direction (perpendicular to the paper surface in the figure). It is driven so as to be divided and conveyed toward the direction. The transport screw 22 is rotationally driven so that the developer is transported from the back to the front in the drawing. A developer discharge portion for discharging the developer to the outside is provided on the front side of the transport screw 22. In the figure, 25 is a doctor blade for leveling the developer adhering to the developing sleeve to a certain amount, and 23 is a casing that covers the developing portion.

  Next, the ionized airflow and the stirring unit, which are features of the present invention, will be described. FIG. 4 is a block diagram of an ionizer 99 which is an ionized airflow generating means. An electrode needle 100 is provided inside the ionizer 99, and positive and negative ions are generated from both electrode needles by applying a positive and negative pulsed high voltage to the electrode needle 100 to cause corona discharge. The generated positive ions and negative ions are converted into an ionized airflow through the airflow port 101 and carried to the ionized airflow inlet through an airflow sent from a propeller, an air pump, or the like. In order to change the positive / negative ion balance, an electrode 102 is provided in the flow path of the ionized air flow as shown in FIG. 4, and ions of opposite polarity are attracted by setting a potential there (FIG. 4 ( In B), positive ions are attracted to the electrodes by setting a negative potential), so that it is possible to generate ions that are biased toward one of the ion balances. In addition, the ionizer 99 generates either positive or negative ions by applying a DC voltage to the electrode needle, or generates ions using soft X-rays or vacuum ultraviolet rays. There is also a type that suppresses the occurrence, and in the present invention, a type suitable for the application can be used.

  FIG. 5 is a cross-sectional view showing a state in which an ionized air flow inlet is provided in the developer discharge flow path from the developing section to the developer stirring section, and the ionized air flow from the ionizer is sent to the developer discharge flow path through the flow path. In the example shown in FIGS. 2 and 5, an ionized air flow inlet 103 is provided via a mesh or porous plate 104 through which carriers cannot pass through the developer discharge flow path 3 from the developing section 2 to the developer stirring section 40. The ionized airflow from the ionizer 99 is sent to the developer discharge flow path 3 through the ionized airflow inlet 103 and the mesh or porous plate 104. As shown in FIG. 5, the ionized air current is blown to the developer moving in the developer discharge flow path 3, and the charge amount of the developer changes by attracting ions to the toner or carrier in the developer ( Reduce).

  FIG. 6 is a schematic diagram of the above-described mechanism. For example, positive ions are attracted to negatively charged toner, toner charge is reduced, and positively charged carriers are attracted by negative ions to reduce charge. . By continuously spraying an ionized airflow over the entire developer discharged from the developing unit, the charge amount of the developer is uniformly reduced.

  Generally, the charge amount of toner varies depending on various factors, and the charge amount varies even under the same stirring condition. For example, the factors include the surrounding environment (temperature and humidity), a decrease in charging performance of the carrier over time, a change in toner charge amount due to the output image area, that is, a difference in charge amount due to toner residence time, and the like. Further, a difference in electrostatic adhesion force occurs due to the difference in charge amount, and the difference between the toner staying in the developing device and the newly supplied toner is remarkable. However, in the present invention, by reducing the difference in charge amount between toners before stirring, the difference in electrostatic adhesion force is eliminated, and the toner staying in the replenishing toner and the developing device is uniformly dispersed in the developer. In addition, the toner charge amount itself can be stabilized.

  FIG. 7 is a diagram showing a cross section and details of a developer stirring unit 40 and a rotary feeder 50 according to another example. The developer stirring unit 40 has a role of stirring the developer and charging the toner, and continuously and stably supplying a developer having an appropriate toner concentration and charge amount. Therefore, it is necessary to stir the developer efficiently in a short time and it is desired that the stress applied to the developer is small.

  The developer stirring section 40 has a shape such as an inverted conical shape that has a diameter that decreases toward the discharge port. A developer supply port 33 is provided on the upper surface, and a discharge port 34 is provided on the lower surface. A screw 43 for conveying the agent from the bottom to the top is provided at the center, and two rotatable plate-like members 44 are provided on the outside thereof, and the developer is mixed by the rotating operation of these stirring members 44. The outer stirring member 44 and the screw 43 are rotated by a stirring motor 45. The screw 43 is directly connected to the motor, and the outer stirring member 44 rotates (decelerates) via the gears 46a to 46d. Gravity is used for conveyance from the supply port to the discharge port in the developer stirring unit 40. Since developer always exists as a buffer in the developer stirring section 40, unmixed developer is not discharged as it is.

  A spiral auger 35 is provided in the toner supply path 31, and one end of the auger 35 is connected to a drive motor 32 as a drive source (see FIG. 2), and is driven to rotate. As a result, the toner is conveyed and replenished in the developer pool, and the replenished toner is quickly mixed and stirred together with the developer by the stirring member 44 which is a plate-like member.

  In the present invention, as described above, the dispersibility of the replenishing toner is improved by adjusting (reducing) the charge amount of the developer discharged from the developing portion by the ionized airflow, so that it is appropriate without applying extra stress. It is possible to quickly adjust to an appropriate charge amount.

  The developer lifted upward from the bottom by the rotation of the screw 43 moves downward along with the rotation of the stirring member 44 that rotates on the outside, and is collected around the screw 47 again. As described above, the developer constantly convects in the accommodating portion in the developer stirring portion 40. By this convection, the entire developer stirring unit 40 is uniformly mixed. Since the toner is charged by the friction between the toner and the carrier, it is important to increase the contact probability between the toner and the carrier in order to quickly obtain the charge amount. As a result of studies by the inventors of the present application, it has been found that the contact probability is increased and the damage to the developer is small due to the convection of the developer in the accommodating portion of the developer stirring unit 40. When the charge amount is reduced before stirring by an ionized air flow as in the present invention, the stirrer of this configuration that can uniformly raise the toner charge amount to an appropriate value is suitable.

  A rotary feeder 50 is connected below the developer stirring unit 40. An impeller 51 is arranged in the inside as shown in the figure and rotates to discharge a certain amount of developer downward. The developer discharged from the rotary feeder 50 is sent from the left to the right in the drawing by the air sent from the air pump 60, and is transported to the developing unit on the air flow. The configuration from the air pump 60 to the air intake port is the same as in FIG.

  FIG. 8 is a perspective view showing a second embodiment of the present invention. In this example, an ionized air flow inlet 103 is provided in the developer supply flow path 4 that is a supply path from the developer stirring section 40 to the developing section 2 in the developer circulation path. If the charge amount of the developer increases too much in the stirring section due to factors such as the surrounding environment (for example, humidity), or the charge amount varies due to deterioration of the developer (charge amount distribution is broad) In some cases, the charge amount of toner that is not used for development because the charge amount is too high, or weakly charged / reversely charged toner is adjusted by blowing an ionized air current on the developer after stirring. It becomes possible. At this time, it is possible to adjust the charge amount more appropriately by adjusting the ion balance of positive ions and negative ions. In addition, when the charged amount of the stirred developer is appropriate, the ionizer is turned off, and energy is not generated unnecessarily by using energy. As a means for detecting the proper charge amount, an indirect prediction can be made from the relationship of a toner density sensor provided in the developing unit and an optical sensor for detecting the toner adhesion amount on the intermediate transfer belt 85 (see FIG. 1). Is possible.

  Further, by making it possible to control the rotation speed of the stirring member 44 of the developer stirring section 40, depending on the use conditions (environment and output image), the rotation speed is increased when the toner charge amount is low, and the rotation speed is increased when it is high. By lowering (stopping when there is no toner supply) and reducing the charge amount with ionized airflow, it becomes possible to obtain an appropriate toner charge amount, such as density unevenness and dirt due to variations in toner charge amount, etc. It is possible to eliminate image quality problems. In addition, by providing ionization air flow inlets in both the developer discharge flow path 3 and the developer supply flow path 4 of the developer circulation path, toner charge amount control can be performed with higher accuracy.

  FIG. 9 is a cross-sectional view showing a third embodiment of the present invention. In this example, the developer agitating unit 40 having the same configuration as that of the second embodiment is provided with the ionized air flow inlet 103 so that the effect described with reference to FIG. 8 can be obtained similarly. Further, when an ionized air flow is introduced into the developer stirring unit 40, the developer in the developer stirring unit 40 is fluidized to reduce stress due to stirring, and at the same time, the toner concentration and charge amount of the developer are made uniform. Is possible.

  FIG. 10 is a cross-sectional view showing a fourth embodiment of the present invention. In this example, by providing the ionized airflow inlet 103 with a mesh or porous plate 104 through which carriers cannot pass, it is possible to suppress the backflow of developer to the inlet and clogging of the inlet. Further, the porous plate 104 is disposed so as to be inclined with respect to the flow of the developer, and ions are introduced from the direction opposite to the moving direction of the developer. If the ionized air flow is simply introduced from the lateral direction with respect to the developer moving direction as in the example shown in FIG. 5, ions are introduced only into a part of the circulating developer, and the ions with respect to the developer. However, if ions are introduced from a direction opposite to the moving direction of the developer as in this example, ions can be uniformly introduced into the moving developer. Can do.

  FIG. 11 is a cross-sectional view showing a fifth embodiment of the present invention, FIG. 12 is a diagram showing a premixing section used in the fifth embodiment of the present invention, and FIG. 13 is a diagram of the fifth embodiment of the present invention. It is a perspective view which shows a structure in detail. In this example, as shown in FIG. 13, the developer discharge flow path 3 is connected to the developer stirring unit 40 via the premixing unit 200. An ionized airflow inlet 103 is connected to the pre-mixing unit 200 to introduce an ionized airflow, and the developer in the developer discharge channel 3 is ionized. As shown in FIGS. 11 and 12, the pre-mixing unit 200 has a developer dispersing member 105 and a mesh 104 arranged in a cylindrical casing 210. The mesh 104 has an inverted conical shape in a cylindrical casing 210, and an ionized airflow can be introduced from a direction opposite to the developer circulation direction. Further, the developer dispersing member 105 is a member in which a roof-shaped member having two inclined surfaces attached to each other with respect to the developer moving direction (in this case, the falling direction) is arranged. Can be dispersed and subjected to ionized airflow.

  In this example, when the developer dispersed on the side surface side of the mesh 104 moves on the mesh 104, the mesh 104 serves as a fluidized bed, and an ionized airflow can be introduced into the entire developer.

  FIG. 14 is a cross-sectional view showing a modification of the fifth embodiment of the present invention. In this example, the developer dispersing member 105 has a conical shape with the apex facing upward. If the developer dispersing member 105 has a conical shape as in this example, the developer can be easily dispersed uniformly, so that an ionized air current can be sprayed uniformly on the developer. The developer dispersing member 105 may be a cone shape such as a triangular pyramid or a quadrangular pyramid in addition to a conical shape.

  FIG. 15 is a cross-sectional view showing a sixth embodiment of the present invention. A toner replenishing port is provided on the upstream side of the ionized air flow introduction port in the middle of the discharge path from the developing unit to the stirring unit, and the helical auger 35 rotates, so that the toner is replenished from the toner supply path 31. . The replenished toner moves in the circulation path together with the developer discharged from the developing unit, and is dispersed in the developer at the ionized air flow introducing unit. The ions are preferentially attracted to the charged toner or carrier to reduce the charge amount, and the newly supplied toner is easily dispersed. Further, since it plays the role of pre-mixing, it can be easily mixed and stirred in the subsequent stirring section, so that the stress on the developer in the stirring section can be suppressed.

  When the pre-mixing unit 200 shown in the fifth and sixth embodiments is used, the developer dispersion member 105 can be made of metal or resin. Further, in order to prevent ions from canceling each other before being blown against the developer or being absorbed by the side surface of the container, a bias voltage is applied to the developer dispersing member 105 to electrically apply ions to the ions in addition to air. A driving force can be applied. Furthermore, the developer dispersing member 105 can be rotated by a rotation axis perpendicular to the direction of gravity, and the stirring effect can be improved. In the above example, the ionized air flow inlet 103 is provided at one location, but the ionized air flow inlet 103 is provided at a number of locations so that the ionized air current can be uniformly sprayed by the developer.

  Further, as described above, in FIG. 2 (also in FIG. 8), the developer discharged from the rotary feeder 50 is sent from the left to the right in the drawing by the air sent from the air pump 60 and rides on the air flow. It is transported to the development unit. By transporting the developer by an ionized airflow from the ionizer 99 instead of the air pump 60, it is not necessary to provide a separate pump, and the developing device can be simplified.

FIG. 16 is a graph showing an experiment example of charge amount control by an ionized airflow, and FIG. 17 is a diagram showing a cylindrical container and a side magnet used in the experiment shown in FIG.
Experimental conditions are
Developer: toner particle size 6 μm, carrier particle size 35 μm
Stirring device: The cylindrical container 106 rotates about the cylindrical axis, and the developer (toner and carrier) inside the container is stirred by the rotational movement and the magnetic force from the side magnet 107 disposed on the side surface of the container (FIG. 17)
Cylindrical container: diameter φ30 mm, height 40 mm, rotation speed 180 rpm,
Side magnet: 1000G, 3000G

  FIG. 16A shows a developer (not before ionizer treatment) in which 5 g of a developer having a toner concentration of 4 wt% is stirred for 20 minutes with the above-described stirring device equipped with a 3000 G side magnet, and is not blown with an ionized airflow after stirring. It is the result of measuring the charge amount distribution of the toner using a charge amount measuring device (trade name E-spart analyzer) of the developer sprayed with an air current (after ionizer processing). The developer as it is stirred has a broad distribution on the highly charged side because of strong stirring. Such a developer has a problem that the image density becomes thin because it is not developed in the developing portion because the adhesion force between the toner and the carrier is strong. On the other hand, the developer sprayed with an ionized air current has a reduced charge amount and a sharp charge amount distribution, so it can be seen that the developer is adjusted to an appropriate charge amount during development, and the development efficiency Is also expected to improve.

  FIG. 16B is a stirrer in which NEW toner is replenished so that the toner concentration becomes 7 wt% in 4 g of the above-described two types of developers (ionizer untreated agent, ionizer treating agent), and a side magnet 1000G is attached. This is the result of stirring for a minute. It can be seen that the developer subjected to the ionizer treatment is shifted to the high-charge side as compared with the developer not subjected to the ionizer, and the charging occurs rapidly. This is considered to be because the replenished toner was quickly dispersed in the toner (developer) that was subjected to strong stress by strong stirring, and the stirring was performed better than the untreated agent of the ionizer.

  In this way, spraying the ionized airflow before stirring improves the dispersibility of the replenishment toner, and by spraying the ionized airflow after stirring, it is possible to adjust the toner with an inappropriate charge amount to an appropriate charge amount. I was able to confirm that there was.

  FIG. 18 is a cross-sectional view showing a seventh embodiment of the present invention. 18A shows a cross section from the axial direction of the developing section, and FIG. 18B shows a cross section from the upper direction.

  In the figure, reference numeral 20 denotes a developing roller, which has a magnet disposed therein, and functions to attract and convey the developer to adhere toner to the electrostatic latent image on the surface of the photoreceptor 1. In the figure, 21 is a first conveying screw, 22 is a second conveying screw, and the first conveying screw 21 is driven so as to be conveyed from the right side to the left side in the longitudinal direction in FIG. The second conveying screw 22 is rotationally driven so that the developer is conveyed from the left side to the right side, and mixes and agitates the toner replenished to part (a) in FIG. 18B during conveyance. While carrying the developer.

  In the figure, 25 is a doctor blade for leveling the developer adhering to the developing sleeve to a certain amount, and 23 is a casing that covers the developing portion. Furthermore, in the present invention, the ionized air flow inlet is provided under the second conveying screw 22 for stirring. The developer is replenished with toner from above the portion (a) in the drawing, fluidized by the ionized airflow and mesh 104 flowing from below in the portion (b), and ions are introduced (the introduced airflow is the upper part). Are discharged to the outside from the filter 24 provided in the The developer into which ions are introduced has a reduced charge amount (there is no difference in electrostatic adhesion between the toner / carrier between the replenishment toner and the toner in the developer), and the replenishment toner is the developer. It becomes easy to be mixed and dispersed inside. Further, the variation in the charge amount itself is reduced, and the developer having the uniform toner density and charge amount is transported by the second transport screw 22 and supplied to the developing roller 20 by the first transport screw 21. At this time, since the toner density and the charge amount are optimized, the image density can be stably maintained over time.

  Here, the reason why the ionized air flow inlet 103 is provided slightly downstream of the toner replenishing port is to prevent the replenished toner from flying up by the ionized air current. Since toner and developer have different specific gravities, if a large amount of toner is replenished, the replenished toner will not mix with the developer, and an upslip will occur. This is because it is considered that this is further promoted, and this configuration can prevent the upper slip.

  FIG. 19 is a schematic view showing an eighth embodiment of the present invention. FIG. 19A is a schematic diagram illustrating the configuration of the developing unit, the developer stirring unit, the rotary feeder unit, and the air pump, FIG. 19B is a schematic diagram illustrating the configuration of the static eliminator, and FIG. 19C is a cross section illustrating the configuration of the static eliminator. FIG.

  In this example, the charging charger 300 is disposed above the developer discharge channel 340 disposed between the developing unit 2 and the developer agitating unit 40 via the porous plate 330, and the developer discharge channel 350 is disposed inside the developer discharge channel 350. The ionized air current generated by the charging charger 300 is sent to the developer passing through. In the charging charger 300, a cable 320 is arranged in a case 310 into which air is introduced, a bias voltage of, for example, 3 kV or more is applied between the case 310 and the cable 320, and ions generated by discharge are sent out by the air. Is. In the figure, reference numeral 350 denotes a developer conveying screw.

  According to the inventor's experiment, when the charging charger according to the present example was used rather than a general ionizer, the amount of ions generated was large, and the effect of eliminating static electricity per unit time was obtained.

  As described above, this is a two-component developing device comprising a toner and a carrier. The developing unit and the developer agitating unit are provided separately, and the developer circulates between the developing unit and the agitating unit to generate an ionized air flow. In the developing device having the means, an ionization airflow inlet for adjusting (reducing) the charge amount of the toner and the carrier is provided in the discharge path from the developing section of the developer circulation path to the developer stirring section. Therefore, it is possible to improve the dispersibility of the replenishing toner, improve the stirring property, and stabilize the toner charge amount. That is, in the conventional electrophotographic developing unit, there is a toner that has been stressed in the developing unit without being consumed and a fresh toner that has been newly replenished (the history of toner in the agent in the unit is different). ing). If you mix and agitate the replenished toner in the presence of toners with different states (such as when the toner additive is buried or removed), the difference in charge amount, Due to the difference in the electrostatic adhesion force, strongly charged toner that is not used for development and weakly charged toner that adversely affects image quality are generated. To solve this problem, the toner / carrier is adjusted by adjusting the toner charge amount before stirring and making the charge amount of the replenishment toner and the toner in the developing device uniform (for example, by reducing the charge amount). The difference in the electrostatic adhesion force between the toner particles becomes small, and the image quality can be kept stable by improving the mixing / dispersibility of the replenishing toner and stabilizing the toner charge amount distribution after stirring. Further, by introducing an ionized air flow as a means for adjusting the charge amount, it becomes possible to uniformly introduce ions into the developer.

  The present invention is also a two-component developing device comprising a toner and a carrier, wherein the developing unit and the developer stirring unit are provided separately, and the developer circulates between the developing unit and the stirring unit to generate an ionized air current. In the developing device having the means, an ionized air flow inlet for adjusting (reducing) the charge amount of the toner and the carrier is provided in at least one of the stirring units in the supply path from the stirring unit to the developing unit of the developer circulation path. The toner charge amount distribution can be stabilized. In other words, the amount of charge can be maintained even if the same amount of charge is circulated through the developing device and the charge amount becomes too high due to excessive agitation, or if the agitation is performed under the same conditions due to differences in the usage conditions (the surrounding environment changes and the image area to be output). Therefore, by adjusting (reducing) the charge amount of the toner (developer) with the ionized airflow, it is possible to reduce the proportion of the strongly charged toner that is not used for development. In addition, since the charge amount distribution can be sharpened, stable image quality can be maintained over time.

  Also, the operation of the ionizing airflow generating means can be arbitrarily turned on / off, and the ion balance of positive ions and negative ions can be arbitrarily controlled, so that proper charge amount adjustment can be achieved, By operating the ionizer according to the developer state (toner concentration and charge amount) and changing its ion balance, it is possible to keep the charge amount appropriate without introducing wastefully into the developer. it can.

  In addition, by providing at least a mesh, a porous plate, or a substitute for the carrier that cannot pass through the ionized airflow inlet, uniform ion introduction into the developer can be achieved. By providing a mesh or a porous plate through which the carrier cannot pass, it is possible to prevent the developer from flowing back to the inlet and to uniformly introduce ions into the developer.

  Furthermore, when the ionized airflow is introduced from the side in the developer circulation direction by introducing the ionized airflow from the direction opposite to the developer circulation direction during the developer circulation, ions are only part of the developer. Although not introduced, it can be sent evenly by sending the airflow from the opposite direction. Further, the developer can be made into a fluid state by combining with a mesh and a porous plate, and ions can be dispersed more uniformly.

  Furthermore, toner dispersibility and agitation are improved by providing a toner replenishment port in the discharge path from the developing unit to the developer agitation unit and upstream of the ionized airflow inlet, and the replenished toner is developed with the ionized airflow. By premixing with the developer, it becomes possible to uniformly disperse in the developer, and the subsequent stirring can be performed efficiently.

  Furthermore, the toner charge amount can be stabilized by arbitrarily controlling the number of rotations of the stirring member of the stirring unit, and when the charge amount is low, the charge amount can be increased by increasing the number of rotations of the stirring member. On the other hand, if the charge amount is high, the charge amount is decreased by an ionizer, so that an appropriate charge amount can be stably obtained as required.

  In addition, the developer circulation means is made (air) conveyance by ionized air current to simplify the apparatus. When air conveyance is used as the developer circulation means, the air for conveyance and ions are sent. It is possible to simplify the apparatus configuration by sharing the air (air flow) with a single pump.

The present invention provides a two-component developing device comprising a toner and a carrier, having an ionized airflow generating means, and providing an ionized airflow outlet in a developer (toner) stirring section, thereby improving the dispersibility of the replenishing toner and stirring. Even if the stirrer and developing unit are not provided separately, the ionized air current is blown when the developer is agitated to adjust the dispersibility and charge amount of the replenishment toner. It is possible to do. That is, even if the developing unit and the stirring unit are not provided separately (for example, a conventional developing device that performs stirring while being conveyed by a screw), a desired effect can be obtained.

1: Photosensitive member 2: Developing unit 3: Developer discharge channel 4: Developer supply channel 5: Developer feeding unit 20: Developing roller 21: First conveying screw 22: Second conveying screw 23: Casing 24: Filter 25: Doctor blade 30: Toner hopper 31: Toner supply path 32: Driving motor 33: Developer supply port 34: Discharge port 35: Conveying screw (auger)
40: Developer stirring part 41: Toner outlet opening 43: Screw 44: Stirring member (plate-shaped member)
45: stirring motor 46: gears 46a to 46d: gear 47: screw 50: rotary feeder 51: impeller 55: motor for driving the rotary feeder 60: air pump 81: apparatus main body 82: charging unit 83: cleaning unit 84: primary Transfer section 85: Intermediate transfer belt 87: Paper feed cassette 88: Secondary transfer section 89: Fixing section 90: Paper discharge section 91: Air suction port 92: External air suction path 93: Dehumidifier 94: Air intake port 99: Ionizer 100: Electrode needle 101: Air flow port 102: Electrode 103: Ionized air flow introduction port 104: Porous plate or mesh 105: Developer dispersion member 106: Cylindrical container 107: Side magnet 200: Pre-mixing unit 210: Housing 300: Charger 310: Case 320: Cable 330: Porous plate 340: Developer discharge channel 350: Screw

JP 2008-003560 A

Claims (14)

A developing device using a two-component developer comprising a toner and a carrier, wherein the developing unit and the developer stirring unit are provided separately, and an ionized air flow generating means is provided, and the developing unit and the developer stirring unit In the developing device in which the developer circulates,
A developing device comprising an ionization airflow inlet for adjusting the charge amounts of toner and carrier in a path through which the developer circulates. The developing device according to claim 1,
A developing apparatus comprising an ionization airflow inlet in a discharge path from the developing unit to the developer stirring unit. The developing device according to claim 1,
A developing device comprising an inlet for introducing an ionized air flow in a supply path from the developer stirring unit to the developing unit. The developing device according to claim 1,
A developing device comprising an ionization airflow inlet in the developer stirring section.   5. The developing device according to claim 1, wherein the operation of the ionized airflow generation unit can be arbitrarily turned on / off, and the ion balance of positive ions and negative ions can be arbitrarily controlled. A developing device. The developing device according to any one of claims 1 to 5, wherein at least a mesh, a porous plate, or a unit having a function equivalent to the carrier through which the carrier cannot pass is arranged at the inlet of the ionized airflow. A developing device. The developing device according to claim 1, wherein an ionized air stream is introduced from a direction opposite to a developer circulation direction during the circulation of the developer. 8. The developing device according to claim 1, wherein the toner replenishing port is transported in a discharge path from the developing unit to the developer agitating unit and to the ionized air flow inlet. A developing device provided on the upstream side in the direction. The developing device according to claim 1, wherein the number of rotations of the stirring member of the developer stirring unit can be arbitrarily controlled. The developing device according to claim 1, wherein the means for circulating the developer is air conveyance by the ionized airflow. The developing device according to claim 1, wherein the adjustment of the charge amount of the toner and the carrier is a reduction of the charge amount. The developing device according to claim 2,
The ionized airflow generating means is provided at the upper part of the discharge path through the ionized airflow inlet,
The ionized airflow generation means includes a case and a wire member that is disposed inside the case and to which a bias voltage is applied between the case, and generates ions generated due to discharge due to application of the bias voltage. A developing device, wherein the developing device is conveyed by an air current fed into a case to form an ionized air current, and an ionized air current is introduced into the discharge path from an inlet of the ionized air current. A developing roller for carrying and transporting the developer;
A first conveying screw for supplying the developer to the developing roller while conveying the developer in the longitudinal direction;
In a developing device including a second transport screw that transports the developer in a direction opposite to the developer transport direction of the first transport screw,
A toner replenishing port for replenishing toner on the upstream side in the developer conveying direction of the second conveying screw;
A developing device, wherein an ionized air flow inlet for introducing an ionized air current is disposed downstream of the toner supply port in a developer transport direction and below the second transport screw. An image forming apparatus comprising the developing device according to claim 1.