JPH0519617A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate the generation of an eddy current from in a developing device, to prevent toner from being stuck, to prevent torque from increasing and to simplify the constitution of the developing device 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 developing sleeve 165 where positive and negative electrostatic charging parts are formed in a specified pattern is provided on the roller 161. The plural electrodes 164 are divided into three electrode groups, and voltage whose polarity is switched in a specified cycle is impressed on each electrode group, then the toner is carried by driving and rotating the developing sleeve 165 by the mutual action of the charge of a developing sleeve electrostatic charging part and the charge of the stator.

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. It is characterized by comprising a sleeve made of a thin film.

[0005]

According to the present invention, by applying a voltage to the plurality of electrodes of the electrostatic actuator member, the driving force is electrostatically generated by the interaction between the charges on the developing sleeve and the charges on the electrostatic actuator. The developing sleeve is rotatably driven so as to convey the toner to the developing section.

[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 the above, the developing device 16 is provided with a toner conveying unit including a developing roller 161 composed of an electrostatic actuator member and a developing sleeve 165 rotatably provided on the surface of the developing roller 161. The developing sleeve 1
A thinning blade 162 that triboelectrically charges the toner and forms, for example, one toner thin layer is provided so that the tip portion abuts on the surface located below the center of 65. 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 includes a base roller 161a that is non-rotatably supported and an electrostatic actuator member that includes a stator 165 made of an insulator and a plurality of electrodes 164 embedded in the stator 165. 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.
Adjacent electrodes are connected to any of different first to third electrode terminals 164a, 164b, 164c to form three drive electrode groups. This drive electrode 1
The pitch of 64 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, it is set to about 0.5 m to 1.0 m. The inner diameter of the developing sleeve 165 is set larger than the outer diameter of the developing roller 161 so that the developing sleeve 165 can smoothly rotate on the peripheral surface of the developing roller 161 based on a driving principle described later. The developing sleeve 165 may have a two-layer structure in which a conductor layer 170 made of metal or the like is laminated on an insulator layer 169 as shown in FIG. 2B, or as shown in FIG. 2C. In addition, a dielectric layer 171 may be further laminated on the conductive layer 170 to form a three-layer structure.
An external electrode is brought into contact with the conductor layer 170 to apply a developing bias. Then, as shown in FIG. 3A, for example, as shown in FIG. 3A, an insulator layer that constitutes 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. The developing sleeve 165 has a thin layer (for example, a thickness of 100 μm) so that it can be deformed in a wavy manner on the developing roller 161 based on a driving principle described later.
Below). When the developing sleeve 165 is provided on the peripheral surface of the developing roller 161, only the developing sleeve 165 is covered on the peripheral surface of the developing roller 161, and the positioning of the developing roller 161 in the radial direction is not particularly 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. In the example of FIG. 3 (b), since the surface layer is made of an insulating layer, the carried toner easily holds the triboelectric charge due to the thinning blade 162 and the like. If the toner is made of an insulating material that can be triboelectrically charged to a predetermined polarity, it is also advantageous in triboelectrically charging the toner. Then, by applying a voltage to the electrode terminals 164a, 164b, 164c of the developing roller 161, as will be 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. The developing sleeve 165 is driven on the peripheral surface of the developing roller, and thereby 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 where it 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 to 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.
Further, 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 developing area which is a contact portion with the thinning blade 162 on the developing sleeve 165 which is rotationally driven by the electrostatic actuator, and is charged by the thinning blade. After being thinned, it reaches the portion facing the photoconductor drum 1 and adheres to the electrostatic latent image on the photoconductor drum 1 to visualize it. 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 the developing roller 161 does not need to be rotated. Therefore, there is no increase in torque due to the generation of an eddy current unlike 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.

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 excess toner that has been thinned by the thinning blade 162 and could not pass through is dropped downward by 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 portions are formed on the inner peripheral surface of the developing sleeve 165. However, instead of this, a single polarity charging portion, for example, only positive charging portions may be formed. . In this case, this charging unit is connected to, 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, it is sufficient that the magnetic toner sent by the agitator 163 can be carried 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.

[0015]

According to the invention of claim 1 or 6, by applying a voltage to the plurality of electrodes of the electrostatic actuator member, the charges on the developing sleeve and the charges on the electrostatic actuator are electrostatically interacted with each other. A driving force is generated, and thereby, the developing sleeve is rotationally driven to convey the toner to the developing unit, so that eddy current is not generated in the developing device, the toner is not melted due to heat generation, and an abnormal image is generated. It is possible to suppress a phenomenon such as occurrence or defective rotation of the developing roller. Further, according to the invention of claim 2, since the sleeve has an inner surface layer made of an insulator and a conductive layer laminated on the inner surface layer, the sleeve can be driven by an electrostatic actuator. A predetermined charge can be held well, and by applying an external voltage to the conductive layer, a development bias for good development can be formed in the development area, and a good image can be obtained. . Further, according to the invention of claim 3, since the surface layer of the sleeve is made of a dielectric material, the charged charge of the toner can be maintained well on the sleeve, and the one-component non-magnetic toner is used. It is also possible to carry out triboelectric charging and carry it on the surface of the sleeve by electrostatic force. Further, according to the invention of claim 4, a magnetic toner is used as the toner, and
Since the sleeve is magnetized, the magnetic toner can be carried and conveyed by the magnetic force on the sleeve peripheral surface. Further, according to the invention of claim 5, the charging thin layer forming means for charging the toner on the sleeve and forming the toner thin layer is provided below the center of the sleeve. When the toner is thinned, excess toner can be dropped downward, and excessive toner can be prevented from being conveyed. Further, according to the invention of claim 6, since the inner diameter of the sleeve is larger than the outer diameter of the roller-shaped electrostatic actuator member, the sleeve can be smoothly rotated on the peripheral surface of the electrostatic actuator member. Is possible.

[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. 4 is a schematic configuration diagram of a developing device according to a modification.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 photoconductor 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 conductive layer, 171 dielectric layer

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

Claims (6)

[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 an sleeve formed of a thin film which 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. apparatus. 2. The image forming apparatus according to claim 1, wherein the sleeve has an inner surface layer made of an insulating material and a conductive layer laminated on the inner surface layer. 3. The image forming apparatus according to claim 1, wherein the sleeve has a surface layer made of a dielectric material. 4. The image forming apparatus according to claim 1, wherein a magnetic toner is used as the toner, and the sleeve is magnetized. 5. A charging thin layer forming means for charging a toner on the sleeve and forming a toner thin layer is provided below the center of the sleeve. 4. The image forming apparatus of 4. 6. The image forming apparatus according to claim 1, wherein the inner diameter of the sleeve is larger than the outer diameter of the roller-shaped electrostatic actuator member.