JPH0519615A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent toner from being stuck in a developing device, to prevent torque from increasing and to simplify the constitution of the developing device by carrying the toner 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 electrodes 164 buried in the stator 165 on a base substance roller 161a supported so that it can not rotate. 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, so that the toner is carried by the mutual action of the charge of the toner 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 this type of image forming apparatus, a developer or toner agitated in the developing device is carried on a surface of a developing roller, which is a developer carrying member, and the developing roller is rotated. Thus, the latent image on the photoconductor is developed by transporting it to a position facing the surface of the photoconductor, which is the electrostatic latent image carrier. After the completion of development, the developer or toner that has not been transferred to the photosensitive member is collected in the developing device by rotating the developing roller, and the developer or toner is newly stirred and charged, and again carried on the developing roller and conveyed. .

[0003]

However, according to the above construction, when the developing roller rotates, the toner enters between the developing roller and the developing side plate, and the toner rubs to cause an abnormality such as toner sticking. Had a negative effect on.
Further, in the case where the developing roller is composed of a developing sleeve including a magnet roller, an eddy current is generated when the developing sleeve crosses the magnetic field of the magnet roller, which increases the torque of rotation of the developing roller and heat of the developing roller. In some cases, the toner was tinged and melted in the developing device. Therefore, the present invention solves the above-mentioned problems by using the electrostatic actuator member to convey the developer or toner on the developing roller without rotating the developing roller, and simplifies the structure of the developing device. The purpose is to make it possible.

[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, an electrostatic actuator member is used as the toner conveying means of the developing apparatus.

[0005]

According to the present invention, the electrostatic actuator member is used as the toner conveying means of the developing device, and a voltage is applied to a plurality of electrodes of the electrostatic actuator, so that the charge of the charged toner and the plurality of electrodes of the electrostatic actuator are A driving force is electrostatically generated by the interaction with the electric charge, and thereby the toner is conveyed.

[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 developing device 16, the developing device 16 is a developing roller 161, which is a toner conveying means, a charging roller 162 that abuts and rotates on the surface of the developing roller 161, and frictionally charges the toner, and conveys the toner in the toner hopper to the vicinity of the charging roller 162. And an agitator 163 for Developing roller 1
61 is a base roller 161a that is non-rotatably supported,
It has an electrostatic actuator member composed of a stator 165 made of an insulator and a plurality of electrodes 164 embedded therein. This plurality of electrodes (hereinafter referred to as drive electrodes) 16
Reference numeral 4 denotes an elongated strip shape in the axial direction of the base roller 161. Adjacent electrodes are connected to one of the first to third electrode terminals 164a, 164b, 164c which are different from each other, and three driving electrodes are provided. An electrode group is formed. The pitch of the driving electrodes 164 in the circumferential direction of the developing roller 161 may be set to, for example, about 10 to 20 μm so that toner particles having a diameter of about 10 μm may be attached in a line on one driving electrode 164. (See FIG. 3).
The toner particles may be attached in a plurality of rows on one drive electrode. Then, these electrode terminals 164
By applying a voltage to a, 164b, 164c as described later, a driving force is generated by the interaction between the electric charge of the toner and the electric charge of the stator to convey the toner.

In the toner hopper, the charging roller 1 is provided.
A black toner that is triboelectrically charged to a positive polarity (+) by 62 is stored. This toner needs to have a predetermined resistance as described later. Then, the toner end detection is performed by detecting the rotation torque of the agitator 163, and assuming that the toner is exhausted in the developing device 16 due to the reduction of the rotation torque to a predetermined value or less, and the toner end is detected. Indicates the toner end to the user by lighting a toner end display (not shown) on the operation unit, for example.

With reference to FIG. 3, the operation principle of, for example, conveying the toner rightward on the electrostatic actuator member by the electrostatic actuator member will be described. Figure 3
As in (a), any of the electrode terminals 164a, 164
There is no charge in the drive electrode 164 when no voltage is applied to b and 164c. On the other hand, the toner is frictionally charged by the charging roller 162 and is positively charged, but since there is no charge on the stator side, the toner is not controlled by the drive electrode 164 and the toner is not conveyed. . At this time, the toner floats around the developing roller 161 or adheres to the stator by some force. From this state, as shown in FIG. 3B, a positive voltage is applied to the first electrode terminal 164a, a negative voltage is applied to the second electrode terminal 164b, and 0V is applied to the third electrode terminal 164c. Then,
The toner is attracted to the drive electrode to which a voltage having a polarity opposite to the charging polarity is applied. That is, + toner adheres to the surface of the developing roller on the drive electrode 164 to which −V is applied. At this time, the toner is not attracted to the drive electrode 164 to which the + V voltage having the same polarity as the toner is applied and the drive electrode 164 to which the applied voltage is not applied. Next, as shown in FIG. 3C, + V having the same polarity as the toner is applied to the second drive electrode group below the adhered toner as shown in FIG. 3C. (In this example, on the right side), the adjacent third electrode group is provided with −V, which has the opposite polarity to the toner, and the first drive electrode group, which is adjacent to the second drive electrode in the toner transport direction, has the same polarity as the toner. Is switched to apply + V. As a result, the charge of the toner has the same polarity as the charge of the drive electrode immediately below it, so that a repulsive force is generated and a levitation force is generated for the toner, and the third drive electrode group in the toner transport direction is 0. Changes from −V to −V and has the same polarity as the toner, the charge of the third drive electrode group attracts the toner at the upper left of the third drive electrode group, and
Since the electric charge of the first drive electrode group opposite to the toner carrying direction has the same polarity as that of the toner, it repels the toner on the upper right of the first drive electrode group, and a rightward driving force is generated on the toner. The levitation force reduces the friction between the toner and the surface of the developing roller, and the driving force of the electric charges causes the toner to move about one pitch of the driving electrode. Next, in order to shift the voltage (FIGS. 3 (c) and 3 (d)) of the pattern for performing repulsion and driving of the toner by one, the applied voltages are changed as shown in FIGS. 3 (e) and 3 (f). Switch.
Thereafter, in the same manner, by applying the driving electrodes while shifting them one by one, the toner is continuously moved. 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 steps in the table, FIGS. 3C and 3D correspond to the steps, and FIGS. 3E and 3F correspond to the steps. The steps include + V, −V, and
+ V is applied, and the voltage of the pattern for repulsing and driving the toner is shifted from the step by one toward the right side in the toner conveying direction. After that, by repeating steps 1 to 3, the voltages of the patterns for repulsing and driving the toner are 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 made positive and the first drive electrode group is made negative, it is possible to drive in the opposite direction.

Here, as the toner of this embodiment, any toner having high resistance or medium resistance can be used as long as it can be triboelectrically charged. However, in the case of the medium resistance toner, the toner is instantly attached to the surface of the developing roller above the drive electrode at the moment when the polarity of the voltage applied to the drive electrode is switched, by the charge of the drive electrode after the switching. If a charge having a polarity opposite to that of the triboelectric charging polarity is induced in the lower part of the toner, it may be attracted by the charge of the driving electrode and a sufficient repulsive force may not be obtained. Therefore, a resistor having a resistance sufficient to obtain a repulsive force when the polarity of the voltage applied to the drive electrode is switched is used.

In the above structure, the toner in the toner hopper is conveyed to the charging roller 162 by the agitator 163, charged to a predetermined polarity by the charging roller 162, and then conveyed to the surface of the developing roller 161. Developing roller 1
The toner on 61 is conveyed by the electrostatic actuator,
It reaches the portion facing the photoconductor drum 1 and adheres to the electrostatic latent image on the photoconductor drum 1 to visualize it. Photoconductor drum 1
The toner that has not adhered to the developing roller 162 returns to the inside of the developing device and is removed from the developing roller 162 by the charging roller 162.

In this embodiment, the plurality of drive electrodes 164 are divided into three drive electrode groups, and the toner is adhered onto one of the three drive electrode groups. , The toner of each polarity is the developing roller 161.
It will be attached to almost 1/3 of the entire circumferential surface of.
Therefore, in order to supply sufficient toner to the latent image on the photoconductor to perform uniform development, the moving speed (conveying speed) of the toner on the developing roller 161 is tripled or more than the linear speed of the photoconductor. It is desirable to do.

As described above, in this embodiment, since the toner is conveyed by using the principle of the electrostatic actuator without rotating the developing roller 161, there is no rubbing portion as in the case of rotating the developing roller 161, and The toner is not stressed at the rubbed portion and the toner is not fixed. Further, since the developing roller 161 does not rotate, the torque is not increased by the generation of the eddy current, and the generation of heat is suppressed, so that the toner in the developing device is not melted.

Further, in the above embodiment, the charging roller 1
62 is arranged in the lower direction than the center of the developing roller 161. This is because when the charged toner that has passed through the charging roller 162 is stacked on the developing roller 161, it drops downward due to gravity. The toner is the developing roller 161.
In the above, since the development is better in the thin layer, the laminated toner is dropped by gravity to form a thin layer. On the contrary, when the charging roller 162 is located above the center of the developing roller, when the toner passes through the charging roller 162 in a stacked state, the toner is conveyed to the developing area with unevenness on the surface of the developing roller. Alternatively, the toner may be accumulated between the charging roller 162 and the developing roller 161.

In the above embodiment, the toner is frictionally charged and used, but it is also possible to carry the toner without frictionally charging the toner. In this case, FIG.
In this state, after the charge having the polarity opposite to the applied voltage polarity of the drive electrode is induced in the lower part of the toner, the voltage to each applied electrode is switched as shown in FIG. Repulsive force is generated to move the toner in the same manner as in the above embodiment. Also in this case, when the polarity of the voltage applied to the drive electrode is switched, a charge having a polarity opposite to the triboelectrification polarity of the toner is instantly induced to the lower portion of the toner by the charge of the drive electrode after the switching. Since there is a risk that sufficient repulsive force will not be obtained due to the electric charge of the drive electrode, it is necessary to use a resistor having a resistance sufficient to obtain sufficient repulsive force when the polarity of the voltage applied to the drive electrode is switched.

Further, in the above embodiment, for example, one kind of positively charged toner is accommodated in the developing device to carry out the development, but instead of this, two different polarities are used.
It is also possible to accommodate toners of various types and similarly convey these toners using an electrostatic actuator member to perform development. In this case, by applying an appropriate developing bias voltage in the developing portion facing the electrostatic latent image on the photosensitive drum 1, the toner charged in each polarity interacts with the electrostatic latent image and the developing bias. It can be attached to the latent image on the photoconductor by the developing electric field formed by. That is, it is possible to perform development having two different types of development characteristics with one developing device. Further, it is also possible to develop the electrostatic latent images corresponding to two kinds of toners and then develop the electrostatic latent images at the same time. At this time, the toners having different polarities may have the same color, but if they have different colors, they are
It is possible to perform color development. An embodiment in which two types of toner having different polarities are housed in the developing device will be described below.

With reference to FIG. 4, the operation principle of, for example, conveying the toner rightward on the electrostatic actuator member by the electrostatic actuator member will be described. Figure 4
As in (a), any of the electrode terminals 164a, 164
There is no charge in the drive electrode 164 when no voltage is applied to b and 164c. On the other hand, the toner is triboelectrically charged by the charging roller 162 and positively or negatively charged, but since there is no electric charge on the stator side, the toner is not controlled by the drive electrode 164 and the toner is not conveyed. Is. At this time, the toner is the developing roller 16
1 Floating around or attached to the stator by some force. From this state, as shown in FIG.
Positive voltage on the first electrode terminal 164a, second electrode terminal 164b
And a negative voltage, and 0 V is applied to the third electrode terminal 164c. Then, the toner is attracted to the drive electrode to which a voltage having a polarity opposite to the charging polarity is applied. That is, if the drive electrode is + V, −toner adheres to the surface of the developing roller on each drive electrode. At this time, the toner is not attracted to the drive electrode to which the applied voltage is not applied. Next, when each applied voltage is switched as shown in FIG. 4C (−V, + V, −V for each of the first to third electrodes), the electric charge of the toner and the electric charge of the drive electrode immediately therebelow have the same polarity. Therefore, the repulsive force is generated and the floating force is generated for the toner. In addition, the electric charge of the third drive electrode group (changed from 0 to −V) repels the upper right toner and attracts the upper left toner, so that a rightward driving force is generated to move the toner. . The levitation force reduces the friction between the toner and the surface of the developing roller, and the driving force of the electric charges causes the toner to move about one pitch of the driving electrode. Next, in order to shift the voltage (FIGS. 4C and 4D) of the pattern for repulsing and driving the toner by one,
Each applied voltage is switched as shown in FIGS. 4 (e) and 4 (f). Thereafter, in the same manner, by applying the driving electrodes while shifting them one by one, the toner is continuously moved. Here, the switching of the applied voltage to each drive electrode group from FIG. 4 (b) to FIG. 4 (f) and thereafter is summarized in Table 2. The steps in the table are shown in FIG. 4B, and the steps are shown in FIGS. 4C and 4D.
4E and 4F correspond to the steps. The step is + V for each of the first to third drive electrode groups,
A voltage of -V, -V is applied, and the voltage of the pattern for repulsing and driving the toner is shifted by one from the step to the right side in the toner conveyance direction. After that, by repeating steps 1 to 3, the voltages of the patterns for repulsing and driving the toner are shifted one by one.

[Table 2] Note that, for example, in FIG. 4C (step), if the voltage applied to the third drive electrode group is made positive, the drive can be performed in the opposite direction.

A specific example of developing a latent image on a photoconductor by a developing device containing two kinds of toners having different polarities by using the above-described toner transport principle will be described. First, an example in which a two-color image is formed by using, for example, a black toner having a negative polarity and a red toner having a positive polarity as the two types of toner will be described. Scan the two color originals, black and red,
In order to form a latent image to be developed with black toner and red toner on the photoconductor, for example, in the image forming apparatus of FIG. 1, the image signal read by the image reading element 10 can be separated into black and red. To Then, first, a positive latent image of a black image is formed on the photoconductor charged positively by the uniform charging charger 15. This is moved to the developing area, and as shown in FIG. 5, the surface of the developing roller is normally developed by a negative black toner of the two kinds of toner conveyed by the electrostatic actuator member under an appropriate developing bias. . While the black toner image is passing through the transfer charger 18, the separation charger 19 and the cleaning device 23 due to the rotation of the photosensitive drum 1, these are kept inoperative. On the other hand, the charging charger 15
From the image forming area which has reached the position, the negative latent image of the red image is formed by recharging to the positive polarity. Then, in the developing area, the negative latent image of the red image is reverse-developed by the positive red toner of the two types of toner conveyed by the electrostatic actuator member under an appropriate developing bias. The black toner image and the red toner image, which are superposed on the photosensitive drum 1 as described above, are transferred to the transfer sent from the paper feeding unit 17 by corona discharge of the transfer charger 17, and the toner image is transferred. After separating the transfer paper from the surface of the photosensitive belt 1 by the separation charger 19, the transfer belt 2
The sheet is conveyed by 1 and discharged through the pressure contact portion of the fixing roller pair 22 to the outside of the machine to obtain a copy of two colors. On the other hand, the toner remaining on the surface of the photoconductor after the transfer is removed by the cleaning device 23.

In this example, the plurality of drive electrodes 164 are divided into three drive electrode groups, and one drive electrode group thereof is negatively charged with black toner, and the other drive electrode group is positively charged. The red toner is attracted, and the toner is not attached to the remaining one drive electrode group. That is,
Black toner is present in approximately 1/3 of the entire peripheral surface of the developing roller 161, red toner is present in the other approximately 1/3 thereof, and toner is not present in the remaining approximately 1/3. Therefore, in order to supply the black toner or the red toner to an arbitrary portion on the photoconductor, the moving speed (conveying speed) of the toner on the developing roller 161 is tripled or more than the linear speed of the photoconductor. Set.

Further, in this example, the latent image of the black image and the latent image of the red image are separately formed and respectively developed, but instead of this, for example, a composite photosensitizer used in a known two-color image forming apparatus. Form each latent image at the same time using the body, and
You may perform each development simultaneously.

Next, a specific example will be described in which a latent image on a photoconductor is developed by a developing device containing two types of toner having different polarities, the same color, for example, black toner.
First, a latent image to be developed with each toner is formed on the photoconductor charged to a predetermined polarity by the uniform charging charger 15. By moving this to the developing area and applying an appropriate developing bias voltage, the toner charged to each polarity carried by the electrostatic actuator member on the surface of the developing roller as shown in FIG. 6 becomes a latent image. The latent image on the photoconductor is supplied to the latent image for development by the development electric field formed by the interaction of the development bias.

In this example, the plurality of drive electrodes 164 are divided into three drive electrode groups, and one drive electrode group among them has a black toner negatively charged, and the other drive electrode group has a black toner positively charged. The toner is attracted to each, and the toner is not attached to the remaining one drive electrode group. That is, black toner is present on approximately ⅔ of the entire peripheral surface of the developing roller 161, and no toner is present on the remaining ⅓. Therefore, in order to supply the black toner to an arbitrary portion on the photoconductor, the moving speed (conveying speed) of the toner on the developing roller 161 is set to 1.5 times or more the linear speed of the photoconductor. To do.

[0023]

As described above, according to the invention of claim 1,
An electrostatic actuator member is used as the developer transporting means of the developing device, whereby toner is supplied to the electrostatic latent image bearing member without rotating the developer bearing member, so that toner is not fixed in the developing device. The torque can also be reduced. Further, the problem of improper application of the developing bias voltage due to the application of the voltage via the bearing of the rotating member unlike the conventional developer carrier does not occur. Furthermore,
According to the invention of claim 2 or 4, by having toners of different polarities in the developing device, it is possible to realize two types of development at the same time, and one developing device can perform two types of development. It is possible to reduce the area occupied by the image forming apparatus main body of the developing device. Further, claim 3
According to the invention, since the toners of different colors are used as the two kinds of toners having different polarities, it is possible to perform the two-color development by one developing device by performing the developing operation once or twice. It is possible to reduce the area occupied by the body of the. Further, according to the invention of claim 5 or 6, the relationship between the linear velocity on the surface of the latent image carrier and the toner transport speed by the electrostatic actuator member is set according to the toner density on the surface of the toner transport member. Sufficient image density can be obtained. Further, according to the invention of claim 7, the toner layer on the surface of the toner conveying means can be favorably thinned by arranging the charging means below the center of the roller-like toner conveying means. Done,
A high quality image can be obtained.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram of a developing device of the image forming apparatus of FIG.

FIG. 3A to FIG. 3F are explanatory views of the toner transport operation principle.

FIG. 4A to FIG. 4F are explanatory views of the toner transport operation principle according to another embodiment.

FIG. 5 is an explanatory diagram for explaining a toner transport state of a developing device according to an example using the toner transport operation principle shown in FIG.

FIG. 6 is an explanatory diagram for explaining a toner transport state of a developing device according to another example using the toner transport operation principle shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 photoconductor drum, 16 developing device 161, developing roller, 162 charging roller 163 agitator, 164 drive electrode 165 stator

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[Procedure amendment]

[Submission date] September 13, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

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

Claims (7)

[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 an electrostatic actuator is used as a toner conveying means of the developing device. An image forming apparatus using a member. 2. The image forming apparatus according to claim 2, wherein two types of toner having different charging polarities are mixed and accommodated in the developing device. 3. The image forming apparatus according to claim 4, wherein the two types of toner have different colors. 4. The image forming apparatus according to claim 4, wherein the two types of toner have the same color. 5. The image forming apparatus according to claim 3, wherein the speed of toner transport by the electrostatic actuator is set to be three times or more the linear speed of the surface of the latent image carrier in the developing area. 6. The toner conveying speed of the electrostatic actuator is set to 1.5 of the linear speed of the latent image carrier surface in the developing area.
7. The image forming apparatus according to claim 6, wherein the number is set to twice or more. 7. The toner conveying means is formed in a roller shape, and the toner is triboelectrically charged and supplied to the surface of the toner conveying means so as to face the surface of the toner conveying means below the center of the toner conveying means. The image forming apparatus according to claim 2, further comprising a toner charging unit.