JP3996363B2 - Development device - Google Patents

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Publication number
JP3996363B2
JP3996363B2 JP2001276809A JP2001276809A JP3996363B2 JP 3996363 B2 JP3996363 B2 JP 3996363B2 JP 2001276809 A JP2001276809 A JP 2001276809A JP 2001276809 A JP2001276809 A JP 2001276809A JP 3996363 B2 JP3996363 B2 JP 3996363B2
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Japan
Prior art keywords
toner
developer
developing device
electrode
electrodes
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JP2001276809A
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JP2003084560A (en
Inventor
正 岩松
弘幸 平川
伸之 東
吉紀 武藤
哲朗 豊島
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シャープ株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic apparatus and a developing apparatus for visualizing an electrostatic latent image. More specifically, the present invention relates to a non-magnetic one-component developer supply / conveying means. It relates to technology that adheres to and transports the body.
[0002]
[Prior art]
As a developer for an electrophotographic apparatus, a one-component developer composed only of toner and a two-component developer composed of toner and carrier are known. A typical developing apparatus using a two-component developer is shown in FIG. In this developing device, the toner 76 is charged by mixing and stirring the toner 76 and the carrier 80 with the stirring roller 79, and the developer carrying member 72 containing the magnet in a state where the toner 76 is adhered to the surface of the carrier 80. Then, the electrostatic latent image carrier 71 and the developer carrier 72 are conveyed to a development area at a position opposite to each other. Therefore, a sufficient transport amount can be obtained and a high density image can be obtained.
[0003]
However, in the case of the two-component developer, it is necessary to maintain the mixing ratio of the toner 76 and the carrier 80 constant in order to maintain the developing density constant, and the configuration of the entire developing device becomes complicated. Further, since the toner powder is deposited and fixed on the surface of the carrier 80 due to the stirring of the toner 76 and the carrier 80 and the charging performance is deteriorated, the carrier 80 needs to be periodically replaced. In addition, the magnet and the carrier 80 increase the cost and weight of the developing device, and further increase the size of the developing device.
[0004]
Therefore, the two-component development method is widely used in copiers that are regularly inspected and serviced by service personnel. However, in printer devices that are managed by users themselves, maintainability, cost, size, weight, etc. The fact is that it is shunned for the reason.
[0005]
On the other hand, a developing apparatus using a one-component developer is easy to handle. As a one-component developer (hereinafter abbreviated as toner), a non-magnetic one-component developer is known. In a non-magnetic one-component developing device, a developer supply member (for example, a toner supply roller made of a sponge or the like) is used, and the developer supply member is pressed against the developer carrying member, thereby supplying toner mechanically and electrically. In this way, the toner is supplied and applied.
[0006]
A general apparatus of this type will be described with reference to FIG. First, an electrostatic image is formed on the surface of the photosensitive member 71 (electrostatic latent image carrier) by a latent image forming unit (not shown), and then a toner 76 (developer carrier) facing the photosensitive member 71 with toner 76 (developer carrier). Non-magnetic one-component developer) is electrostatically attached and developed, and the electrostatic image is visualized.
[0007]
In this developing process, a thin layer of charged toner 76 is formed on the developing roller 72. In forming a thin layer of the toner 76, first, the toner 76 is supplied and applied to the developing roller 72 by a toner supply roller 77 (developer supply member) disposed in the developing tank 75 and pressed against the developing roller 72. Thereafter, a thin layer of the toner 76 adhering to the developing roller 72 is made uniform by a blade 74 which is a developer layer regulating member.
[0008]
The toner 76 is generally charged by friction charging or charge injection charging by rubbing between at least one of the developing roller 72 and the toner supply roller 77 or between the developing roller 72 and the blade 74. .
[0009]
In such a developing device using a non-magnetic one-component developer, a shortage of toner supply becomes a problem when a developing process that consumes a large amount of toner is performed as in a solid black document. That is, unlike the two-component development method, the toner cannot be conveyed by the carrier, so that the toner supply amount corresponding to the toner consumption amount on the developing roller 72 cannot be maintained, and the phenomenon that the density gradually decreases tends to occur.
[0010]
As a conventional technique for solving this problem, for example, it is widely known to use a magnetic toner instead of the non-magnetic toner as a one-component developer. Since the magnetic toner can be conveyed by being magnetically attracted by a magnetic force, it is possible to supply a sufficient amount of toner corresponding to the amount of toner consumption to the developing roller 72. However, since the magnetic toner adds magnetic powder to the main resin of the toner, it becomes difficult to color and it is difficult to cope with colorization.
[0011]
Therefore, it is advantageous to use a non-magnetic toner as the one-component developer. However, in this case, there is a problem that the toner is transported, the toner is charged, and the toner is uniformly and thinly formed on the developer carrier.
[0012]
That is, in the case of non-magnetic toner, since toner cannot be conveyed by magnetic force, it is necessary to devise a toner conveying method. In the case of using magnetic toner, the toner adheres to the developing roller by magnetic force. In the case of non-magnetic toner, the toner adheres to the developing roller mainly due to mirror image force and van der Waals force. Therefore, if the toner layer thickness is not formed as a thin layer, the toner will fall off or scatter from the developing roller.
[0013]
Furthermore, if the toner is charged by frictional charging with the developing roller 72 or the blade 74, the charge amount is inversely proportional to the toner layer thickness, so a uniform thin layer must be formed in order to obtain a stable and high toner charge. It becomes.
[0014]
As a toner conveying method in a developing device using non-magnetic toner, as shown in the above-described conventional example, there are a number of techniques disclosed as a method using a toner supply roller and the like.
[0015]
For example, as disclosed in Japanese Patent Application Laid-Open No. 58-98762 and US Pat. No. 4,083,326, there is a method of using a fiber brush as a toner supply roller. That is, the toner contained in the fiber brush can be supplied by bringing the toner supply roller having the fiber brush on the surface into contact with the developing roller. A method of using an elastic foam as a toner supply roller is disclosed in Japanese Patent Laid-Open No. 2-191974. In this method, toner is supplied by including the toner in a foam cell of an elastic foam.
[0016]
[Problems to be solved by the invention]
However, when the toner supply roller 77 made of a fiber brush or an elastic foam is used, the toner supply roller 77 needs to be brought into pressure contact with the developing roller 72 in order to obtain a sufficient toner supply amount. At the pressure contact portion between the toner and the developing roller 72, the toner is stressed and the toner is likely to deteriorate. Further, there arises a problem that the driving torque of the developing roller 72 is increased.
[0017]
Further, when a fiber brush is used as the toner supply roller 77, deterioration with time such as toner clogging between the brushes and brush falling is likely to occur. Even when an elastic foam is used, deterioration with time due to toner clogging in the foam cell tends to occur.
[0018]
In addition, the provision of the toner supply roller 77 and its driving device complicates the structure of the developing device, and the simplicity of the device, which is one of the advantages of using a one-component developer, is lost, and the cost increases. There is also a problem.
[0019]
The present invention has been made in view of such circumstances, and allows toner to be adhered and transported onto the developing roller without using a developer supplying member that is pressed and rubbed against the developing roller, thereby sufficiently supplying the non-magnetic one-component developer. It is an object of the present invention to provide a developing device that can be carried out at the same time, is less susceptible to toner stress and toner deterioration over time, and can stably obtain a high-density image.
[0020]
[Means for Solving the Problems]
In the present invention, means for solving the above-described problems are configured as follows.
[0021]
(1) In a developing device provided with a blade that regulates the layer thickness of the developer on the downstream side of the developer adhesion region where the nonmagnetic toner is deposited on the developer carrier.
  A periodic conductive electrode pattern is provided on the surface of the developer carrying member carrying the non-magnetic toner via an insulating portion, and a conductive member that is in electrical contact with the conductive electrode pattern in the developer adhesion region is provided. ,
  Through the conductive memberOf the developer adhesion regionThe conductive electrode patternBetween the electrodesInOnly forBy applying the desired bias potential, near the developer carrier surfaceBetween the electrodesAn electric field gradient is generated, and the non-magnetic toner is adhered and conveyed onto the developer carrying member.
  The blade is for regulating the layer thickness of the toner on the developing roller formed by toner conveyance. In the present invention, the movement of the blade is controlled by the electric field acting between the developing roller photoreceptors in the developing region. As described above, the toner has a function of charging the toner by friction with the blade and by applying a predetermined voltage to the blade. The developing step is a step of moving the charged toner on the developing roller to the photosensitive member by the action of Coulomb force in the developing region, and is not different from a normal case.
  Accordingly, the bias applied for toner conveyance according to the present invention can independently provide the conveyance bias and the development bias in the development region without disturbing the development bias.
  In addition to the above members, when there is a member having an electric action on the outer periphery of the developing roller, it is preferable to perform an operation without applying a bias according to the present invention even in a region where the member is disposed. For example, a member provided to neutralize charged toner on the developing roller corresponds to the downstream side of the developing region.
[0022]
In this configuration, the electric field gradient generated in the vicinity of the surface of the developer carrier can generate a force called a gradient force on the toner particles. It can be adhered and conveyed on top.
[0023]
A comparison with the conventional method is as follows.
When the toner is rubbed between the members to apply a frictional charge and adheres to the roller with a mirror image force Fi, the mirror image force Fi acting on the toner particles having the charge amount q and the particle diameter d is expressed by a mathematical formula as known in the art. It is shown in 1.
[0024]
[Expression 1]
[0025]
Where εp Is the relative dielectric constant of the developer carrier.
[0026]
On the other hand, when the toner is adhered and transported with an electric field gradient as in the present invention, the diameter d and the relative dielectric constant εtThe force Fg acting on the toner particles is expressed by Equation 2.
[0027]
[Expression 2]
[0028]
That is, even if the toner is not charged, by creating a gradient of the electric field, biased polarization occurs in the toner particles, and a force called a gradient force can be generated in the toner particles.
[0029]
In the present invention, by utilizing the gradient force Fg, the toner can be adhered to the developer carrying member, and the toner can be conveyed along with the rotation of the carrying member.
[0030]
(2) The electrode pattern includes a striped electrode group extending in the axial direction of the developer carrying member, and a plurality of electrodes are arranged with a predetermined gap in the moving direction of the developer carrying member. It is characterized by having installed.
[0031]
When a voltage is applied to the electrode, the electrode has the same potential and a uniform electric field is generated in the vicinity of the electrode, so that an electric field gradient does not occur. However, as in this configuration, a striped electrode extending in the axial direction is developed. An electric field gradient can be effectively generated in the direction of movement of the carrier by arranging the agent carrier at a predetermined interval in the direction of movement and applying a voltage to the electrodes.
[0032]
More specifically, the axial direction of the electrode is Y, the direction perpendicular to the axial direction on the surface of the developer carrier (the direction of the adjacent electrode) is X, and the direction perpendicular to the axial direction and away from the developer carrier is Z. When defined, the electric field gradient that produces the gradient force ▽ E2 Is shown in Equation 3.
[0033]
[Equation 3]
[0034]
By extending a striped electrode in the axial direction of the developer carrying member, and repeatedly arranging the stripe electrode with a predetermined gap in the moving direction of the developer carrying member, the electric field Ez in the Z direction changes in the X direction. And the electric field gradient component of the first term of the above formula is generated. Therefore, the electric field gradient ▽ E represented by Equation 32Can be produced effectively.
[0035]
(3) The electrode pattern group is in contact with the non-magnetic toner through an insulating layer.
[0036]
This configuration can be realized, for example, by forming an electrode on an insulating member such as polyimide and then bonding the electrode forming side with an insulating film. Thereby, generation | occurrence | production of the unwanted leak between electrodes can be prevented.
[0037]
(4) The bias potential is characterized in that different potentials are applied alternately.
[0038]
In this configuration, the electric field gradient can be concentrated on the electrode.
FIG. 6 is an analysis result showing an equipotential line 30, an electric force line 31, and a gradient force vector 32 when + 60V and + 300V voltages are alternately applied to electrodes formed at an electrode pitch of 600 dpi (at 42 μm intervals). It is an example.
[0039]
By applying voltages having the same polarity but different magnitudes, the gradient force 32 can be concentrated and act on a specific electrode portion. The gradient force is a smaller force than the coulomb force, but a force equivalent to the coulomb force can be generated by concentrating on the electrode portion. In the figure, a state in which the toner 15 is attached on the electrode to which a voltage of +300 V is applied is illustrated.
[0040]
In this case, the force to attach the toner does not work in a place where there is no electrode (for example, on the electrode to which + 60V is applied and between the electrodes to which + 60V and + 300V is applied). The toner layer having a uniform thickness can also be formed in the circumferential direction by leveling with.
[0041]
(5) The bias potential is characterized in that a positive potential and a negative potential are alternately applied.
[0042]
In this configuration, the electric field gradient can be applied at a place other than on the electrode, so that the toner can be adhered at a part other than the electrode. Therefore, the toner can be formed more uniformly on the developing roller.
[0043]
(6) The absolute values of the positive potential and the negative potential are equal.
[0044]
FIG. 7 shows an analysis result representing an equipotential line 30, an electric force line 31, and a gradient force vector 32 when -120V and + 120V voltages are alternately applied to electrodes formed at an electrode pitch of 600 dpi (at 42 μm intervals). It is.
[0045]
By alternately applying voltages with different polarities, it is possible to generate an electric field gradient even on the part where there is no electrode on the developing roller, and by making the absolute values of the positive and negative potentials equal, Regardless of this, the values of the electric field gradient can be made uniform, and a more uniform adhesion force can be generated on the developer carrier. In this case, the adhesion force is smaller than when the electric field gradient is concentrated on the electrode portion, but a toner layer with less unevenness can be adhered.
[0046]
In FIG. 7, on the electrode to which the voltage of +120 V is applied, between the electrode to which the voltage of +120 V is applied and the electrode to which the voltage of −120 V is applied, and also on the electrode to which the voltage of −120 V is applied, A state in which the toner 15 is attached is illustrated. As described above, it is possible to more uniformly adhere the toner as compared with the case where the voltage having the same polarity is applied.
[0047]
Therefore, it is not necessary to add a function of uniformly leveling toner to a layer thickness regulating member such as a doctor blade disposed on the downstream side, and the pressing force against the developing roller can be reduced.
[0053]
  (7)When the interval between the electrode pattern groups is p and the width of the electrode is d, the sizes of p and d are set to be substantially equal.TheFeatures.
[0054]
In this configuration, a toner layer with less unevenness can be adhered on the developer carrying member, and the pressure when leveling with the blade can be reduced.
[0055]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a developing device according to an embodiment of the present invention will be described in detail with reference to the drawings.
[0056]
First, a schematic configuration of an electrophotographic apparatus to which the present invention is applied will be described with reference to FIG. The photoreceptor 2 is an electrostatic latent image holding member having a drum or belt structure that is rotationally driven in a direction indicated by an arrow. Various image forming process means are arranged so as to face the periphery of the photoreceptor 2.
[0057]
The image forming process means is formed on the surface of the photoreceptor 2 by being exposed by the charger 3 for uniformly charging the surface of the photoreceptor 2, the optical system 4 for irradiating an image with light corresponding to the image, and the optical system. A developing device 11 including a developing roller (developer carrying member) 1 for making the electrostatic latent image visible, and a transfer for transferring the developed toner image onto the sheet-like paper P that is appropriately conveyed There are a device 5, a cleaning device 6 that removes the residual developer that has not been transferred, a static eliminator 7 that removes the charged charges remaining on the surface of the photoconductor 2, and the like, arranged in this order in the rotation direction of the photoconductor 2. Yes.
[0058]
The sheet P is sent to a transfer area facing the photoconductor 2 where the transfer unit 5 described above is disposed. The sheet P to which the toner image has been transferred is peeled off from the photoreceptor 2 and sent to the fixing device 8.
[0059]
Next, the construction of the developing apparatus to which the present invention is applied will be described with reference to FIG. The developing device 11 includes a nonmagnetic toner 15 as a developer, a developing roller 1 as a toner carrier for holding the nonmagnetic toner 15, and a stirring roller 14.
[0060]
Further, a doctor blade 12 (see FIG. 4) for charging the developing roller 1 with the non-magnetic toner 15 after being conveyed is provided on the downstream side of the conveying region. As a result, in the developing region (the region where the developing roller 1 and the photosensitive member 2 face each other), the toner on the developing roller 1 moves on the photosensitive member 2 in accordance with the electric field between the developing roller 1 and the photosensitive member 2, thereby developing. Is done. The doctor blade also has a function of making the toner layer formed by adhering and transporting to the developing roller 1 uniform and limiting it to a predetermined thickness.
[0061]
The stirring roller 14 plays a role of pouring (supplying) the nonmagnetic toner 15 to the developing roller 1. Normally, when the amount of the nonmagnetic toner 15 is sufficient, the developing roller 1 and the nonmagnetic toner 15 inevitably come into contact with each other. However, when the amount of the nonmagnetic toner 15 decreases, the contact area between the nonmagnetic toner 15 and the developing roller 1 is increased. Less. The stirring roller 14 can positively bring the nonmagnetic toner 15 into contact with the developing roller 1 even when the nonmagnetic toner 15 is reduced.
[0062]
The developing roller 1 and the photosensitive member 2 holding the electrostatic latent image rotate in contact with each other, and the electrostatic latent image is developed by the nonmagnetic toner 15 held on the developing roller 1.
[0063]
   A negatively charged toner having an average particle diameter of 7 μm as non-magnetic toner 15 is placed in a developer tank having a structure as shown in FIG. 1, and periodic electrodes 21 and 22 (conductive electrodes) as shown in FIG. Pattern) and a voltage was applied to the electrodes 21 and 22 to generate an electric field gradient.
[0064]
Hereinafter, the configuration of the developing device of the present invention will be described in more detail.
FIG. 4 is a view of the developing device 11 as viewed obliquely from above. A blade 12 is disposed almost immediately above the developing roller 1, and a photoreceptor 2 (not shown) is disposed downstream thereof.
[0065]
A power source VB for generating a desired electric field between the photosensitive member 2 and the developing roller 1 in the developing region 24 is connected to the core of the developing roller 1. The power source VB outputs a direct current or a bias voltage in which an alternating current is superimposed on the direct current.
[0066]
A feature of the developing roller 1 of the present invention is that a plurality of electrodes extending in the axial direction are formed on the surface thereof. In order to obtain a better effect, the electrodes are divided into two groups, and the same voltage is applied to the electrodes belonging to the same group.
[0067]
In addition, every other electrode is formed so as to be shifted in the width direction of the developing roller 1 so that a voltage from a power source can be applied to the electrode. The number of groups and the voltage supply method are not limited to the above.
[0068]
Conductives for applying a predetermined voltage from the external power sources V1 and V2 to the electrodes 21 and 22 located downstream of the developing region 24 and upstream of the position where the blade 12 is disposed. Sheets 23a and 23b are arranged in contact with each other.
[0069]
In the figure, the conductive sheet 23a is electrically connected to the four electrodes 21 formed by extending in the + Y direction, and the conductive sheet 23b is formed by four electrodes formed by extending in the -Y direction. An example in which the conductive sheet 23b is configured to be electrically connected to the three electrodes 22 formed by extending in the -Y direction so as to be electrically connected to the electrode 21. Show.
[0070]
The conductive sheets 23a and 23b are preferably disposed so as to be in contact with the electrodes 21 and 22 outside the required developing width (for example, 297 mm in the case of A3 vertical). If the structure is disposed within the developing width, it is necessary to expose and form the electrodes 21 and 22 in contact with the conductive sheets 23a and 23b, and there is a problem such as a short circuit between the electrodes as described later.
[0071]
Further, the conductive sheet 23a is extended to the side surface (front side in the figure) of the developing roller 1, the conductive sheet 23b is extended to the other side surface of the developing roller 1, and electrical connection is performed on the side surface of the developing roller 1. May be.
[0072]
In addition, the number of electrodes that are electrically connected to the conductive sheets 23a and 23b is illustrative, and is not limited to the above value, and may be arbitrarily set so that a sufficient amount of toner is conveyed onto the developing roller 1. It can be set.
[0073]
The conductive sheets 23a and 23b are fixed to the housing or the like of the developing device 11 via an insulating member. Therefore, the electrodes 21 and 23 can be electrically connected to the conductive sheets 23a and 23b by the rotation of the developing roller 1. Only the voltage from the power sources V 1 and V 2 can be supplied to the power source 22.
[0074]
Moreover, you may make it press to the electrode parts 22 and 23 reliably by using a spring etc. Moreover, it is good to form in a thin layer so that the outer shape of the developing roller 1 may be followed.
[0075]
Further, the power supplies V1 and V2 are configured such that their voltage values can be set independently. The voltage values output from the power supplies V1 and V2 may be controlled so as to be variable by a control unit such as a CPU (not shown).
[0076]
In the production of the developing roller 1, as described later, a method in which an insulating member such as a polyimide film having electrodes formed thereon is attached to the outer periphery of a normal developing roller.
[0077]
   As shown in FIG. 5, an FPC having an electrode width w of 50 μm, an electrode pitch p of 120 μm, and a sheet thickness d of 120 μm is prototyped and attached to the developing roller 1, and a built-in experiment is performed as a developing device as shown in FIG. It was.
[0078]
A voltage of +400 V / −400 V was applied to the electrode portions 21 and 22. The toner adhesion amount M / A per unit area before passing through the blade is 1 to 2 mg / cm.2 The required amount of toner could be adhered.
[0079]
The specific charge amount Q / M of the toner at this time is 0.7 μC / g, and it has been found that the uncharged toner is attached by the suction force due to the electric field gradient. The toner after passing through the blade is 0.3 mg / cm2We were able to regulate.
[0080]
For comparison, the same experiment was attempted in the supply roller type developing tank shown in FIG. The toner adhesion amount M / A per unit area before passing through the blade is 13.1 mg / cm2It was found that excessive toner adhered to the developing roller and had to be scraped off with a blade.
[0081]
In this embodiment, the FPC electrode is wound around the developing roller 1 and the experiment is performed. However, the developing roller having the electrode structure can be integrally manufactured and carried out.
[0082]
   In FIG. 5, the electric field Ez changes and an electric field gradient is generated when the electrode surface is separated by h in the Z direction. However, when the gap h from the electrode surface is large, Ez is rapidly attenuated and the change in Ez is also small. Therefore, the electric field gradient can be effectively used when the gap h is originally 0 or smaller.
[0083]
However, when h is 0, that is, when the electrodes are exposed, when conductive particles such as gear wear powder or conductive foreign matter are covered on different electrodes, the gap between the electrodes leaks. , May lead to electrode and power supply damage. Therefore, in the embodiment of FIG. 1, the electrodes are covered with a 10-25 μm polyimide insulating layer except for the contact portions with the conductive sheets 23a, 23b. As a result, there was no leakage even during continuous operation.
[0084]
   Electrodes 21 and 22 formed at an electrode pitch of 600 dpi (at intervals of 42 μm) were arranged on the developer carrier 1 as shown in FIG. 4 and incorporated as a developing device as shown in FIG. When the voltage was applied alternately so that +60 V was applied to the electrode 21 and +300 V was applied to the electrode 22, the toner was concentrated on the electrode 22 and adhered.
[0085]
In this state, since the toner layer has a layer thickness unevenness in the circumferential direction, the toner layer is uniformly leveled by the doctor blade 12 to make the toner layer uniform. An arc leaf spring mechanism 12 was used as a blade mechanism for uniformly flattening the toner layer. The thickness of the arc leaf spring is 0.2 mm, the radius of the arc portion is 2.6 mm, the length of the flat plate portion is 14 mm, and when regulated by a linear pressure of 40 gf / cm, it is about 0.3 mg / cm.2 A uniform toner layer was obtained.
[0086]
   As shown in FIG. 4, in order to apply the voltage Vl to the electrode 21, the conductive sheet member 23 a connected to the power source is brought into close contact with the peripheral end of the developing roller 1, and the voltage V <b> 2 is applied to the electrode 22. The conductive sheet member 23b was brought into close contact, and a voltage was applied to the electrodes 21 and 22 only when the developing roller 1 was in contact with the toner in the hopper.
[0087]
That is, a doctor blade 12 is provided on the upstream side of the developing region 24 facing the photosensitive member 2, and the conductive sheet 23 a connected to the peripheral ends of the developing roller 1 on the upstream side of the doctor blade 12 with the electrodes 21 and 22, respectively. , 23b are provided.
[0088]
In the configuration as described above, the nonmagnetic toner 15 adheres to the developing roller 1 with a gradient force due to an electric field gradient, and the adhering nonmagnetic toner 15 is developed with a mirror image force even in a region where the doctor blade 12 is frictionally charged and no voltage is applied. It is held by the roller 1.
[0089]
In the developing unit, the nonmagnetic toner 15 charged according to the potential difference between the electrostatic latent image Vi and the developing bias VB is developed. By applying a bias to the electrodes 21 and 22 only when the non-magnetic toner 15 is transported to the developing roller 1, the transport bias does not interfere with the developing bias, so that development characteristics can be stabilized. It was.
[0090]
   Electrodes 21 and 22 formed at an electrode pitch of 600 dpi (at an interval of 42 μm) were arranged on the developing roller 1 as shown in FIG. 4 and incorporated as a developing device as shown in FIG. When a voltage of −120 V was applied alternately to the electrode 21 and a voltage of +120 V was applied to the electrode 22, the toner adhered not only to the electrodes 21 and 22 but also to the gaps. In this state, since the toner layer is too thick, the doctor blade 12 was uniformly leveled to make the toner layer uniform.
[0091]
An arc leaf spring mechanism 12 was used as a blade mechanism for uniformly flattening the toner layer. As a result of the experiment, about 0.3 mg / cm at a linear pressure of 20 gf / cm or less.2 A uniform toner layer was obtained.
[0092]
As described above, a desired toner layer thickness can be formed on the developing roller 1 with a smaller blade pressure by making the electrode width and the electrode pitch substantially equal and applying a voltage having a different polarity and an equal magnitude to adjacent electrodes. It was.
[0093]
【The invention's effect】
The present invention has the following effects.
[0094]
(1) A periodic conductive electrode pattern is provided on the surface of the developer carrying member carrying the non-magnetic toner via an insulating portion, and a desired bias potential is applied to the electrode so that the developer carrying member is provided near the surface. An electric field gradient is generated and the toner is adhered and transported on the developer carrier, so that a non-magnetic one-component toner is formed on the developer carrier and is transported without pressing the toner supply member against the toner carrier. Can be made. Therefore, the developing device is simplified, the developer carrying member can be driven with a smaller load torque, and the entire device can be reduced in size and weight.
[0095]
In addition, since the step of preliminarily triboelectrically charging is unnecessary and the toner can be adhered and transported onto the carrier without contact, the stress applied to the toner can be reduced, toner fusion can be prevented, and a long-life printer can be realized.
[0096]
Conventionally, it has been difficult to apply a non-magnetic one-component development system to a printer with 20 ppm or more due to insufficient supply of toner. However, according to the present invention, the same supply as a magnetic development system in which magnetic toner is adhered and conveyed by a magnet roller is used. Followability can be obtained, and non-magnetic one-component toner can be applied to a high-speed machine.
[0097]
Further, since it is a non-magnetic toner, it is suitable for colorization and can be widely used as a developing engine for future electrophotographic systems regardless of monochrome, color, low speed, and high speed.
[0098]
(2) Since the electrode pattern is composed of a striped electrode group extending in the axial direction of the developer carrying member, and a plurality of electrodes are provided with a predetermined gap in the moving direction of the developer carrying member. The gradient of the electric field can be effectively generated in the moving direction of the carrier.
[0099]
(3) Since the electrode pattern group is in contact with the toner through the insulating layer, it is possible to prevent undesired leakage between the electrodes.
[0100]
(4) Since different potentials are alternately applied to the bias potential, the electric field gradient can be concentrated on the electrode.
[0101]
(5) Since a positive potential and a negative potential are alternately applied to the bias potential, an electric field gradient can be applied at a place other than on the electrode, so that the toner can be adhered to a portion other than the electrode. it can. Therefore, the toner can be formed more uniformly on the developing roller.
[0102]
(6) Since the absolute values of the positive potential and the negative potential are equal, the value of the electric field gradient can be made uniform regardless of the location, and a more uniform adhesion force can be generated on the developer carrier. In this case, the adhesion force is smaller than when the electric field gradient is concentrated on the electrode portion, but the toner can be more uniformly adhered. Therefore, it is not necessary to add a function of uniformly leveling toner to a layer thickness regulating member such as a doctor blade disposed on the downstream side, and the pressing force against the developing roller can be reduced.
[0103]
(7) The bias potential applied to the electrode is applied only when the non-magnetic toner is adhered to the carrier, and the bias to the electrode is not applied in the process of regulating the adhered toner or the process of developing. The bias applied for toner conveyance according to the present invention can independently provide the conveyance bias and the development bias in the development region without disturbing the development bias.
[0104]
(8) When the interval between the electrode pattern groups is p and the width of the electrode is d, the sizes of p and d are set to be approximately equal, so that a toner layer with less unevenness can be deposited on the developer carrying member. It is possible to reduce the pressure when leveling with the blade.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an electrophotographic system employing a developing device according to an embodiment of the present invention.
FIG. 2 is a schematic sectional view of a two-component developing device.
FIG. 3 is a schematic sectional view of a non-magnetic one-component developing device.
FIG. 4 is a perspective view of a developer carrier according to an embodiment of the present invention.
FIG. 5 is a configuration diagram showing the same electrode pattern and bias application conditions.
FIG. 6 is an example of an analysis result indicating an electric field gradient in the vicinity of the toner and a magnitude / direction of a gradient force acting on the toner.
FIG. 7 is another example of the analysis result indicating the electric field gradient in the vicinity of the toner and the magnitude and direction of the gradient force acting on the toner.
FIG. 8 is a diagram showing a schematic configuration of the electrophotographic apparatus.
[Explanation of symbols]
1-developer carrier (developing roller)
15-Non-magnetic toner
21,22-electrode

Claims (7)

  1. In a developing device provided with a blade that regulates the layer thickness of the developer on the downstream side of the developer adhesion region for adhering the non-magnetic toner to the developer carrier,
    A periodic conductive electrode pattern is provided on the surface of the developer carrying member that carries the non-magnetic toner via an insulating portion, and a conductive member that is in electrical contact with the conductive electrode pattern in the developer adhesion region is provided. ,
    By which the electric field gradient between the electrodes of the developer carrying member surface vicinity by providing a desired bias potential only for via the conductive member between the electrodes of the conductive electrode pattern of the developer attachment region,
    A developing device, wherein the non-magnetic toner is adhered on the developer carrying member.
  2.   The electrode pattern is composed of a striped electrode group extending in the axial direction of the developer carrier, and a plurality of electrodes are arranged with a predetermined gap in the moving direction of the developer carrier. The developing device according to claim 1, wherein:
  3.   The developing device according to claim 1, wherein the electrode pattern group is in contact with the non-magnetic toner through an insulating layer.
  4.   The developing device according to claim 1, wherein different bias potentials are alternately applied as the bias potential.
  5.   The developing device according to claim 1, wherein a positive potential and a negative potential are alternately applied as the bias potential.
  6.   The developing device according to claim 1, wherein absolute values of the positive potential and the negative potential are equal.
  7.   The developing device according to claim 6, wherein when the interval between the electrode pattern groups is p and the width of the electrode is d, the sizes of p and d are set to be substantially equal.
JP2001276809A 2001-09-12 2001-09-12 Development device Expired - Fee Related JP3996363B2 (en)

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Cited By (2)

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US8433211B2 (en) 2009-09-14 2013-04-30 Ricoh Company, Ltd. Developing device, process cartridge, and image forming apparatus
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JP2007133376A (en) 2005-10-13 2007-05-31 Ricoh Co Ltd Development device and image forming apparatus
US7783235B2 (en) 2006-10-13 2010-08-24 Ricoh Company, Ltd. Hopping toner development apparatus and image formation apparatus
JP2008286931A (en) 2007-05-16 2008-11-27 Ricoh Co Ltd Developing device, process cartridge and image forming apparatus
JP5051526B2 (en) 2007-07-10 2012-10-17 株式会社リコー Developing device, process cartridge, and image forming apparatus
JP5067846B2 (en) 2007-07-18 2012-11-07 株式会社リコー Developing device, process cartridge, and image forming apparatus
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JP5327573B2 (en) * 2007-10-31 2013-10-30 株式会社リコー Developing device, process unit, and image forming apparatus
JP5143622B2 (en) * 2008-05-12 2013-02-13 東海ゴム工業株式会社 Developing member for electrophotographic apparatus and method for producing the same

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Publication number Priority date Publication date Assignee Title
US8433211B2 (en) 2009-09-14 2013-04-30 Ricoh Company, Ltd. Developing device, process cartridge, and image forming apparatus
US8594540B2 (en) 2010-01-25 2013-11-26 Ricoh Company, Limited Development device, process cartridge incorporating same, and image forming apparatus incorporating same

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