JPH0519618A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate the generation of an eddy current in a developing device, to prevent toner from being stuck, to prevent torque from increasing and to accomplish uniform development in the developing area by carrying the toner to a developing area without rotating a developing roller. CONSTITUTION:The developing roller 161 is constructed by providing an electrostatic actuator member constituted of a stator 165 made of an insulating material and plural driving electrodes 164 buried in the stator 165 on a base substance roller 161a supported so that it can not rotate. A counter electrode 172 on which developing bias is impressed is buried in the developing area corresponding part of the stator 165. The developing sleeve 165 where positive and negative electrostatic charging parts are formed in a specified pattern is provided on the roller 161. Specified voltage whose polarity is switched in a specified cycle is impressed on the plural electrodes 164, and the developing sleeve 165 is driven to be rotated to carry the toner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile or a printer, and more particularly to a developing apparatus which conveys a developer or toner onto the surface of a latent image carrier to develop the image. .

[0002]

2. Description of the Related Art Conventionally, in a developing device of an image forming apparatus of this type, the developer or toner agitated in the developing device is carried on the surface of a developing roller which is a developer carrying member, and the developing roller is rotated. After thinning the developer or toner with a thin layer blade, etc., the latent image on the photoconductor is developed by transporting it to the developing area facing the surface of the photoconductor, which is the electrostatic latent image carrier. . After the development was completed, the developer or toner that was not transferred to the photosensitive member was collected in the developing device by rotating the developing roller, the developer or toner was newly stirred and charged, and the developer or toner was conveyed again to the developing area by the developing roller. .

[0003]

In the above-mentioned prior art, when the developing roller is composed of a developing sleeve (mainly made of aluminum) containing a magnet roller, eddy current is generated by the developing sleeve crossing the magnetic field of the magnet roller. As a result, the torque of the rotation of the developing roller is increased and the developing roller is heated to melt the toner or the developer in the developing device. When the toner or developer melts out, aggregates, and solidifies, a phenomenon called so-called firefly occurs and adversely affects the image. Further, the toner or the developer may enter between the developing roller and the developing side plate to be fixed, and the developing roller may not rotate. Therefore, according to the present invention, it is possible to solve the above-mentioned problems by transporting the developer or toner without using an electrostatic actuator member and generating an eddy current and simplify the structure of the developing device. The purpose is to

[0004]

To achieve the above object, the present invention provides an image provided with a developing device for supplying toner onto a latent image carrier to develop the latent image on the latent image carrier. In the forming apparatus, the toner conveying means is provided with a roller-shaped electrostatic actuator member, and is rotatably provided on the peripheral surface of the electrostatic actuator member and has a predetermined electric charge to be driven by the electrostatic actuator member. And a counter electrode having a predetermined voltage applied to a region on the electrostatic actuator member corresponding to a developing region where the sleeve and the latent image carrier face each other. To do.

[0005]

According to the present invention, a voltage is applied to a plurality of electrodes of the electrostatic actuator member to electrostatically generate a driving force by the interaction between the charges on the sleeve and the charges on the electrostatic actuator, thereby rotating the sleeve. Then, the toner is conveyed to the developing area, and in the area, the toner on the sleeve adheres to the latent image on the latent image carrier faithfully under the application of the developing bias by the counter electrode to develop the toner. Is.

[0006]

EXAMPLES The present invention will be described based on examples. First,
FIG. 1 illustrates a schematic configuration of the entire image forming apparatus according to an embodiment.
Based on the above, the overall schematic configuration and operation will be described. A photosensitive drum 1 (for example, an organic photosensitive member; OPC), which is one configuration example of a latent image carrier, is rotationally driven in the clockwise direction. When a document is placed on the contact glass 2 and a print switch (not shown) is pressed, the scanning optical system 5 including the document illumination light source 3 and the mirror 4 and the scanning optical system 8 including the mirrors 6 and 7 are moved, Scanning of the original is performed. Then, the scanned image is read as an image signal by the image reading element 10 provided behind the lens 9. The read image signal is digitized and image-processed. Then, the laser diode (LD) is driven by the image-processed signal. The laser light from the LD is reflected by the polygon mirror 13 and then is irradiated onto the photosensitive drum 1 via the mirror 14. As a result, optical writing with the laser light is performed on the photoconductor drum 1, and an electrostatic latent image is formed on the surface of the photoconductor drum that has already been uniformly charged by the charging charger 15. The electrostatic latent image is visualized by the developing device 16, and the visible image is transferred to the transfer paper sent from the paper supply unit 17 by corona discharge of the transfer charger 18. Then, the transfer paper on which the visible image is transferred is separated from the surface of the photoconductor belt 1 by the separation charger 19, and then is conveyed by the conveyance belt 21 and passes through the pressure contact portion of the fixing roller pair 22 to form the visible image. It is fixed and discharged outside the machine. On the other hand, the toner remaining on the surface of the photoconductor after the transfer is removed by the cleaning device 23.

Next, the developing device 16 will be described. Figure 2
In (a), the developing device 16 includes a developing roller 161 composed of an electrostatic actuator member and the developing roller 16.
1 is provided with a developing sleeve 165 rotatably provided on the surface of the toner carrier 1. A thinning blade 162 for frictionally charging the toner and forming, for example, one toner thin layer is provided so that the front end contacts the surface of the developing sleeve 165 located below the center of the developing sleeve 165. A toner replenishing roller 166 is provided on the surface of the developing sleeve below the contact portion between the two, to convey the toner to the corresponding contact portion. The toner replenishing roller 166 can be composed of an elastic roller that can frictionally charge the toner to a predetermined polarity. In this example, a non-magnetic one-component toner is used, and an agitator 163 for conveying the non-magnetic one-component toner in the toner hopper to the vicinity of the toner replenishing roller 166 is provided. The developing roller 161 is a base roller 161 that is non-rotatably supported.
An electrostatic actuator member composed of a stator 165 made of an insulator and a plurality of electrodes 164 embedded in the stator is provided on a. Then, the counter electrode 172 made of a conductor is also embedded on the peripheral surface side of the plurality of electrodes 164 only in a region facing the developing region of the stator 165 of the electrostatic actuator member, and the counter electrode 172 is not shown. It is connected to the power supply for developing bias. The plurality of electrodes (hereinafter, referred to as drive electrodes) 164 each have an elongated strip shape in the axial direction of the base roller 161, and as shown in FIG. 3A, adjacent electrodes are different from each other. Third electrode terminals 164a, 164b, 164c
Connected to any of the above, forming three drive electrode groups. The pitch of the driving electrodes 164 in the circumferential direction of the developing roller 161 is appropriately set in relation to the driving force and the driving speed for the developing sleeve 165. For example, 0.
It is set to about 5 m to 1.0 m. The developing sleeve 1
65 is a developing roller 161 based on a driving principle described later.
The inner diameter of the developing roller 161 is set larger than the outer diameter of the developing roller 161 so that it can be smoothly rotated on the peripheral surface. The developing sleeve 165 may have a two-layer structure in which an insulating layer 169 is laminated on the back side of a base material 170 made of a dielectric material as shown in FIG. 2B, or as shown in FIG. 2C. In addition, a dielectric layer 171 may be further laminated on the base material 170 to have a three-layer structure. Further, when the insulator layer 169 is made of a material having sufficient durability against deformation described later, the base material 170 can be omitted. Then, as shown in FIG. 3A, for example, as shown in FIG. 3A, an insulating layer forming an inner peripheral surface so that it can be partially attracted or repelled by a predetermined drive electrode 164 of the developing roller 161 based on a drive principle described later. For example, positive and negative charges are applied to the developing roller 169 at a predetermined pitch in the developing roller circumferential direction in the developing sleeve longitudinal direction (developing roller axial direction) to form a belt-shaped charging portion. The pitch of the charging section in the developing roller circumferential direction is, for example, opposed to the same pitch of the drive electrodes 164 of the developing roller 161, and a non-charging section is partially provided. Further, the developing sleeve 165 is formed into a thin layer (for example, a thickness of 100 μm or less) so that it can be deformed in a wavy manner on the developing roller 161 based on a driving principle described later. When the developing sleeve 165 is provided on the peripheral surface of the developing roller 161, the developing sleeve 165 is provided.
Since only the 61 circumferential surface is covered, positioning of the developing roller 161 in the radial direction is not required. Regarding the axial direction of the developing roller, abutting members or the like may be provided at both ends of the developing roller 165 in the axial direction at positions corresponding to the both ends of the developing sleeve 165 for positioning. Incidentally, FIG.
In the example of (b), since the surface layer is composed of the insulating layer, the carried toner easily holds the triboelectric charge due to the thinning blade 162 and the like. It is also advantageous to triboelectrify the toner if it is made of an insulating material that can be triboelectrically charged. And
The electrode terminals 164a, 164b of the developing roller 161,
By applying a voltage to 164c as described later,
A driving force for the developing sleeve 165 is generated by the interaction between the electric charge of the developing sleeve 165 and the electric charge of the stator, and the developing sleeve 165 is driven on the peripheral surface of the developing roller, so that the toner on the developing sleeve 165 is conveyed. .

The toner end is detected by the agitator 163.
Of the toner is detected, and the toner is considered to have run out of toner in the developing device 16 due to the rotation torque falling below a predetermined level. When the toner end is detected, for example, an operation unit (not shown) The toner end display of is turned on to notify the user of the toner end.

The operation principle of toner conveyance by the electrostatic actuator member will be described with reference to FIG. Figure 3
As in (a), any of the electrode terminals 164a, 164
In the initial state where no voltage is applied to b and 164c,
There is no charge on the drive electrode 164 in the stator 167. The toner on the developing sleeve 165 is thinned by the blade 1.
The toner is frictionally charged by 62 to cause a predetermined charge of + or −. Development sleeve 16 carrying this toner
As described above, the inner peripheral surface of No. 5 is provided with + and-charging portions in a predetermined pattern, but since there is no charge on the side of the stator 167, it is not governed by the drive electrode 164 and toner is not transported. It is in a state that is not done. From this state,
As shown in (b), a positive voltage is applied to the first electrode terminal 164a,
Negative voltage on the second electrode terminal 164b, third electrode terminal 164c
0V is applied to. Each charging portion of the developing sleeve 165 is
A voltage having a polarity opposite to the charging polarity is attracted to the drive electrode to which a voltage is applied. That is, the − of the developing sleeve 165
The charging portion is attracted to the + V driving electrode, and the + charging portion is attracted to the −V driving electrode and adheres to the surface of the developing roller on each driving electrode. At this time, since the developing sleeve 165 is not attracted onto the drive electrode to which the applied voltage is not applied and the inner diameter of the developing sleeve 165 is larger than the outer diameter of the developing roller 161, the developing sleeve 165 is deformed into a wavy shape. To do. Next, each applied voltage is switched as shown in FIG. 3C (-V, + V, -V for each of the first to third electrodes).
Then, since the charged portions of the developing sleeve 165 have the same polarity as the electric charges of the drive electrodes immediately thereunder, a repulsive force is generated and a floating force is generated on each charged portion of the developing sleeve 165.
The electric charge of the third drive electrode group (changed from 0 to −V) repels the developing sleeve charging portion on the upper right side and attracts the developing sleeve charging portion on the upper left side to the developing sleeve 165. Driving force in the right direction is generated. At this time, the levitation force reduces the friction between the inner peripheral surface of the developing sleeve 165 and the surface of the developing roller, and the driving force of the electric charges causes the developing sleeve 165 to move about one pitch of the driving electrode. next,
In order to shift the voltage of the pattern (FIG. 3C) for performing repulsion and driving with respect to the developing sleeve charging portion by one,
Each applied voltage is switched as shown in (d). Thereafter, similarly, the developing sleeve 165 is continuously moved by applying a voltage while shifting the drive electrodes one by one as shown in FIGS. 3E and 3F. Here, a summary of the switching of the applied voltage to each drive electrode group from FIG. 3 (b) to FIG. 3 (f) and thereafter is as shown in Table 1. 3B corresponds to the step in the table, FIG. 3C corresponds to the step, FIG. 3D corresponds to the step, and FIG. 3E corresponds to the step. After that, step ~
By repeating the above, the voltage of the pattern for repulsing and driving the toner is shifted one by one.

[Table 1] Note that, for example, in FIG. 3C (step), if the voltage applied to the third drive electrode group is set to + V, the drive can be performed in the opposite direction.

In the above structure, the toner in the toner hopper is supplied to the toner replenishing roller 1 by the agitator 163.
After being conveyed to 66, the toner replenishing roller 166 conveys the toner to a contact portion of the developing sleeve 165 which is rotationally driven by the electrostatic actuator with the thinning blade 162, and is charged and thinned by the thinning blade. After that, it reaches the developing area, which is the portion facing the photosensitive drum 1. In this development area, as shown in FIG.
Since a desired developing electric field is formed by 2, the toner is surely attached to the latent image on the photoconductor drum 1, and thereby the latent image on the photoconductor drum 1 is faithfully visualized. The toner that has not adhered to the photoconductor drum 1 returns to the developing device again and is removed.

As described above, in the present embodiment, the present invention uses the principle of this electrostatic actuator to develop the developing sleeve 165.
The toner is conveyed by rotating the developing roller 161 and thereby the developing roller 161 does not need to be rotated. Therefore, there is no increase in torque due to the generation of eddy current as in the case of rotating the developing roller, and the generation of heat is suppressed. Therefore, the toner in the developing device does not dissolve.

Further, in this embodiment, since the counter electrode 172 is provided in the developing area, the counter electrode 172 is provided in the developing area as shown in FIG. 4B, for example. It is possible to obtain a clean image without unevenness without causing the toner adhesion to the latent image on the photoconductor drum to become unstable, resulting in an image having a mottled pattern. If such a counter electrode 172 is not provided, the developing gap, which is the gap between the surface of the photosensitive drum and the surface of the developing sleeve, must be made considerably narrower than that of the counter electrode 172. Although it is difficult to manage the gap in this portion, in this embodiment, since the counter electrode 172 is provided, the gap can be set relatively wide, and the gap management becomes easy. Further, since the counter electrode 172 is provided on the developing roller 161 which is fixedly arranged, the electric connection for applying the developing bias from the power source is, for example, when the developing bias is applied to the rotating conventional developing sleeve or the like. Is easier than. Further, since the counter electrode 172 is provided only in the developing area, there is no obstacle to the driving of the developing sleeve 165 due to the charge of the driving electrode 164 in other areas, and a sufficient driving force can be given to the developing sleeve 165. I can. Further, the counter electrode 172 is made of a conductor, so that the electric field of the drive electrode 164 below the counter electrode 172 is prevented from reaching the charged portion of the developing sleeve 165 in the developing area. The developing sleeve 165 in the area is not deformed, and good development can be performed.

In the above embodiment, the contact position of the thin layer blade 162 with the developing sleeve 165 is set lower than the center of the developing roller 161. This is because extra toner, which has been thinned by the thinning blade 162 and could not pass through completely, drops downward due to gravity when it is stacked below the contact portion between the developing sleeve 165 and the thinning blade 162. is there. Since a thinner layer (preferably one layer) of toner can be developed better on the developing sleeve 165, the excess toner selected by the layer-thinning blade 162 is dropped by gravity. When the thinning blade 162 is in contact with the surface of the developing sleeve above the center of the developing roller, the thinning blade 16
Excess toner that could not pass through 2 is development sleeve 1
65 and the thinning blade are laminated to prevent the movement of the developing sleeve 165 or to be accumulated in an excessive amount, which is conveyed to the developing area and causes an abnormal image such as toner scattering. In order to prevent this, the thinning blade is set so as to abut on the surface below the center of the developing roller, and the developing sleeve 1
The toner on the surface of No. 65 is always thinned to enable good development.

In the above embodiment, the positive and negative charging parts are formed on the inner peripheral surface of the developing sleeve 165. However, instead of this, a single polarity charging part, for example, only positive charging parts may be formed. . In this case, this charging unit is, for example, the developing roller 1
61 drive electrodes 164 are formed to have an alternate pitch (formed so that only one of the three drive electrodes has a charging portion), and the developing sleeve 1 is formed in the same manner as in FIG.
When moving 65 to the right with respect to the peripheral surface of the developing roller, a voltage is applied to the first to third drive electrode groups as shown in Table 2 below.

[Table 2] Note that, for example, in FIG.
If the voltage applied to the drive electrode group of 1 is positive and the voltage applied to the first drive electrode group is negative, it is possible to drive in the opposite direction.

Further, although the above embodiment uses the non-magnetic one-component toner, the present invention can be applied to the one using the magnetic toner. In this case, the developing sleeve 165 can be made to have a magnetic force so that the magnetic toner can be carried by the magnetic force. For this purpose, for example, in the developing sleeve 165 of the configuration example of FIG. 2B, a rubber magnet is finely magnetized as the dielectric layer 171 and, for example, a magnetic force of about 1 pole per 1 to 1.5 mm. It may be about 200 to 300 gauss. In this case, as the toner replenishing roller 166 in the above embodiment, the magnetic toner sent by the agitator 163 may be transported to the vicinity of the peripheral surface of the developing sleeve. Therefore, a rotating bar is used as shown in FIG. You can also Further, it is also possible to use a two-component developer consisting of a carrier and a toner.

[0016]

According to the first aspect of the invention, the electrostatic actuator member is provided on the developing roller and the developing device having the developing sleeve formed of a thin film on the outer periphery of the developing roller is used. Will not occur. As a result, the dissolution of the toner due to the generation of heat is eliminated, and it is possible to suppress the occurrence of abnormal images, the defective rotation of the developing roller, and the like. Then, a counter electrode to which a predetermined voltage is applied is provided in a region on the electrostatic actuator member corresponding to a developing region where the sleeve and the latent image carrier face each other, whereby a desired developing electric field is formed. , Development that is faithful to the latent image can be performed. Furthermore,
According to the invention of claim 2, since the magnetic toner is used as the toner and the sleeve is magnetized,
Magnetic toner can be carried and conveyed by magnetic force on the sleeve peripheral surface. Further, according to the invention of claim 3, as in the invention of claim 1, eddy current is not generated in the developing device. As a result, the dissolution of the toner due to the generation of heat is eliminated, and it is possible to suppress the occurrence of abnormal images, the defective rotation of the developing roller, and the like. Then, a conductive member is provided in a region on the electrostatic actuator member corresponding to the developing region where the sleeve and the latent image carrier face each other, whereby the electrostatic actuator member below the counter electrode is provided. Since the driving electric field is prevented from affecting the electric charge of the sleeve in the developing area, the sleeve in the developing area is not deformed and good development can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

2A is a schematic configuration diagram of a developing device of the image forming apparatus of FIG. 1, FIG. 2B is a sectional view showing a configuration of a developing sleeve and a developing roller of the developing device, and FIG. 2C is a modification. FIG. 3 is a cross-sectional view illustrating a developing sleeve.

FIG. 3 is an explanatory view of a transporting operation principle of the developing sleeve of the present invention.

FIG. 4A is an explanatory diagram for explaining a movement of toner in a developing region of the developing device, and FIG. 4B is an explanatory diagram for explaining a movement of toner in a developing region when a counter electrode is omitted. .

FIG. 5 is a schematic configuration diagram of a developing device according to a modification.

[Explanation of reference numerals] 1 photosensitive drum, 16 developing device 161 developing roller, 162 thinning blade 163 agitator, 164 drive electrode 165 sleeve, 166 toner replenishing roller 167 stator, 169 insulating layer 170 base material, 171 dielectric material Layer 172 Counter electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeru Yoshiki             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh

Claims (3)

[Claims] 1. An image forming apparatus comprising a developing device for supplying toner onto a latent image carrier to develop the latent image on the latent image carrier, wherein the toner carrying means comprises a roller-shaped electrostatic actuator member. And a sleeve which is rotatably provided on the peripheral surface of the electrostatic actuator member and which is made of a thin film having a predetermined electric charge so as to be driven by the electrostatic actuator member. An image forming apparatus characterized in that a counter electrode to which a predetermined voltage is applied is provided in a region on the electrostatic actuator member corresponding to a developing region facing the carrier. 2. The image forming apparatus according to claim 1, wherein a magnetic toner is used as the toner, and the sleeve is magnetized. 3. An image forming apparatus comprising a developing device for supplying toner onto a latent image carrier to develop the latent image on the latent image carrier, wherein the toner carrying means is a roller-shaped electrostatic actuator member. And a sleeve which is rotatably provided on the peripheral surface of the electrostatic actuator member and which is made of a thin film having a predetermined electric charge so as to be driven by the electrostatic actuator member. An image forming apparatus characterized in that a conductive member is provided in a region on the electrostatic actuator member corresponding to a developing region facing the carrier.