JP3169028B2 - Image forming device - Google Patents

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 an electrophotographic copying machine, a facsimile, and a printer. More specifically, the present invention relates to a developer conveying device for conveying a developer and a toner to the surface of a latent image carrier. It relates to improvement of means.

[0002]

2. Description of the Related Art In a conventional developing device, a developing roller as a developer conveying means is rotated to transfer a developer or toner carried on the surface of the developing roller to an electrostatic latent image on a photosensitive member as a latent image carrier. Had been transported. After the development, the developer or toner not transferred to the photoconductor is collected again in the developing device by the developing roller, and the developer or toner is newly carried on the developing roller and transported to the photoconductor.

[0003]

However, according to the above configuration, when the developing roller rotates, the toner enters between the developing roller and the side plate of the developing device that supports the developing roller, and the toner is rubbed to cause the toner to stick. Had an adverse effect on the image. Further, in the case where the developing roller is constituted by a developing sleeve with a built-in magnet roller, an eddy current is generated when the developing sleeve crosses the magnetic field of the magnet roller,
As a result, the torque of the developing roller may be increased, or the developing roller may be heated to melt the toner in the developing device. Also, in an image forming apparatus in which a plurality of developing devices using toners of different colors are arranged on a latent image carrier and one of the developing devices is selectively operated to form a multicolor image, a latent image carrier is used. In order to prevent a plurality of toners from mixing on the body, it is necessary to switch the operation of the developing device. Conventionally, the switching operation of the active developing device uses a method of moving the developing device from the latent image carrier, and has a problem that a moving mechanism is required. Further, in an image forming apparatus in which the developing device is configured to be attachable to and detachable from the main body, if toner is present on a developing roller portion exposed inside and outside the device at the time of taking out operation from the main body of the developing device, toner is generated. There was a problem of scattering.
Accordingly, the present invention provides an electrostatic actuator transport member as a developer transport unit of a developing device, which transports a developer or a toner without rotating a member carrying the developer, and further includes an electrostatic actuator transport member. It is an object of the present invention to provide a developing device capable of solving the above-mentioned problem by controlling the driving of the developing device.

[0004]

To achieve the above Symbol purpose SUMMARY OF THE INVENTION The invention of Claim 1, developing the latent image on the latent image bearing member supplies toner onto the latent image bearing member developing in the image forming apparatus including the apparatus, and a developer conveying unit of the developing device
Upper Te, a first electrostatic actuator conveying member constituting the toner path for discharging the toner toward the latent image bearing member surface from the developing device, the toner discharged from the developing device
Is opposed to Kisenzo carrier, and with one having a second electrostatic actuator conveying member constituting the toner path for recovering in the developing apparatus, after the development operation is finished, the first electrostatic
When the actuator transport member is not operating, the second electrostatic
Drive control to operate the actuator transport means
A drive control means is provided . Ma
According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect.
And a hopper for accommodating toner, and toner from the hopper.
Is rotated in contact with the first electrostatic actuator member.
And a member that is triboelectrically charged.
You. The invention according to claim 3 is the image form according to claim 1 or 2.
In the forming apparatus, the electrostatic actuator transfer member is
First to third adjacent three electrodes are sequentially different from each other
The first to third drive electrode groups connected to the electrode terminals of
They are arranged side by side in the transport direction, and
In the third electrode terminal, one has the opposite polarity to the toner and the other two have
The voltage of the pattern having the same polarity as the toner becomes the opposite polarity
Cut so that the electrodes are shifted one by one at the first to third electrodes.
It is characterized in that the voltage is applied while changing.

[0005]

According to the present invention, there is provided a first electrostatic actuator conveying member which constitutes a toner path for discharging toner from the inside of the developing device toward the surface of the latent image carrier as a toner conveying means of the developing device, and the toner discharged from the developing device. A second electrostatic actuator transport member that forms a toner path for collecting the collected toner in the developing device, and applying a charge to a plurality of electrodes of each of the two electrostatic actuators to charge the toner. The driving force is generated electrostatically by the interaction between the generated charge of the toner and the charges of the plurality of electrodes of the electrostatic actuator, and thereby the toner is conveyed. And
When it is necessary to collect the toner existing in a portion exposed to the outside of the electrostatic actuator conveying means into the developing device, only the second electrostatic actuator conveying member is driven to transfer the second electrostatic actuator conveying member. The toner present on the member is collected in the developing device.

[0006]

FIG. 1 shows a schematic configuration of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus includes:
In order to enable color image formation, two developing devices are provided facing the photosensitive drum surface. First, an outline of the entire apparatus will be described. A photoconductor drum 1 (for example, an organic photoconductor; OPC) serving as a latent image carrier is driven to rotate clockwise. When a document is placed on the contact glass 2 and a print switch (not shown) is pressed, a scanning optical system 5 including a document illumination light source 3 and a mirror 4 and a scanning optical system 8 including mirrors 6 and 7 move. Is read. Then, the scanned image is read as an image signal by an image reading element 10 provided behind the lens 9. The read image signal is digitized, separated and converted for each color corresponding to the output device, and further subjected to image processing. A laser diode (LD) (not shown) is driven based on the image-processed signals, and a laser beam from the LD is reflected by a polygon mirror 13 and then emitted onto the photosensitive drum 1 via a mirror 14. Thereby, the optical writing by the laser beam is performed on the photosensitive drum 1,
An electrostatic latent image is formed on the surface of the photosensitive drum that has been uniformly charged by the charging charger 15. This electrostatic latent image is visualized by two developing devices, a first developing device 16a and a second developing device 16b, and this visible image is transferred to a transfer sheet fed from a paper feeding unit 17 by a transfer charger 18. Is transferred by corona discharge. After this transfer, the transfer paper is separated from the surface of the photosensitive drum by the separation charger 19. The separated transfer paper is conveyed by a conveyance belt 21, passes through a contact portion of a fixing roller pair 22, and is discharged outside the apparatus after a transfer image on the transfer paper is fixed. On the other hand, the toner remaining on the surface of the photoconductor after the transfer is removed by the cleaning device 23. Here, in the two-color image formation, a process of forming a corresponding latent image on the photosensitive drum and a process of visualizing the corresponding developing device is performed by one rotation of the photosensitive drum for each color. The rotation may be performed by one rotation cycle. For example, the first developing device 16a and the second
An optical writing unit for forming a second-color latent image is provided between the developing devices 16b (not shown). After forming and developing the first-color latent image, the second-color latent image is successively formed. The formation and development may be performed to form a two-color image by one rotation of the photosensitive drum, or a two-color image may be formed by another known two-color image forming method.

Next, the developing device will be described. In FIG. 2, the first developing device 1 faces the photosensitive drum surface.
6a and a second developing device 16b. The first developing device 16a uses a one-component non-magnetic toner of a color color, for example, red, and the second developing device 16b uses a one-component non-magnetic toner of a black color, for example. Both developing devices have the same configuration except that the color of the toner used is different. Second developing device 16
Explanation will be made based on b. The developing device 16b includes a developing roller 161 which is a toner conveying unit, and a charging roller 162 which rotates in contact with the surface of the developing roller 161 to frictionally charge the toner.
And an agitator 163 for transporting the toner in the toner hopper to the vicinity of the charging roller 162. The developing roller 161 is a non-rotatably supported base roller 1.
An electrostatic actuator member including a stator 165 made of an insulator and a plurality of electrodes (hereinafter, referred to as drive electrodes) 164 embedded therein is provided on 61a. The electrostatic actuator member includes a first electrostatic actuator transport member 166a that forms a toner path for discharging toner from inside the developing device toward the surface of the latent image carrier,
It is divided into two parts, a second electrostatic actuator conveying member 166b which forms a toner path for collecting the toner discharged from the inside of the developing device into the developing device. Specifically portion facing the photosensitive drum 1 is constituted by a second electrostatic actuator conveying member 166 b, the charging roller 162 is divided so as to be opposed to the first electrostatic actuator conveying member 166 a. Each electrostatic actuator transport member 1
66a and 166b, the plurality of drive electrodes 164
Each of the base rollers 161 has a strip shape elongated in the axial direction. The pitch of the drive 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 adhere to one drive electrode 164 in a line. (FIG. 3
Further, the width and the pitch in the same circumferential direction may be set larger than the above, and the toner particles may be attached in a plurality of rows on one drive electrode. Then, in the first electrostatic actuator transport member 166a, for example, as shown in FIG.
Are connected to any one of the electrode terminals 164a, 164b, and 164c to form three drive electrode groups. Similarly, in the second electrostatic actuator transport member 166b, adjacent electrodes have fourth to fourth electrodes different from each other. It is connected to one of the sixth electrode terminals to form three drive electrode groups.
The first to third electrode terminals 164a, 164b, 164c for the first electrostatic actuator transfer member 166a
And the fourth to sixth electrode terminals of the second electrostatic actuator transfer member 166b are the same as the transfer members 166 and 166.
b are connected to respective drive circuits so as to be able to independently control the drive. These electrostatic actuator transfer members 166a and 166b apply a voltage to the first to third electrode terminals 164a, 164b and 164c and the fourth to sixth electrode terminals as described later, so that toner is transferred. The driving force is generated by the interaction between the electric charge and the electric charge of the stator, and the toner is conveyed.

In the toner hopper of each of the developing devices 16a and 16b, toner that is frictionally charged to, for example, positive polarity (+) by the charging roller 162 is stored. As the toner, a conventionally well-known one-component toner having, for example, a charge control agent added to the toner resin so as to be capable of frictionally charging to a predetermined polarity and having a resistance sufficient to hold the triboelectric charge is used. Can be done. The toner end detection is performed by detecting the rotation torque of the agitator 163, and assuming that the toner has run out of the developing device 16 and has reached the toner end due to the rotation torque having decreased to a predetermined value or less. For example, a not-shown toner end indicator on the operation unit is turned on to notify the user of the toner end.

Referring to FIG. 3, a description will be given of the principle of operation of conveying the toner, for example, rightward in the figure by the electrostatic actuator conveying member. In the illustrated example, as can be seen from the reference numbers of the electrode terminals, the first electrostatic actuator transport member 1
The operation principle of the second electrostatic actuator transport member 166b is the same as that of the second electrostatic actuator transport member 166b. FIG.
As shown in (a), any of the electrode terminals 164a, 164
When no voltage is applied to b and 164c, there is no charge in the drive electrode 164. On the other hand, although the toner is frictionally charged by the charging roller 162 and is positively charged, the toner is not controlled at all by the drive electrode 164 because there is no charge on the stator side, 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 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, + 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 voltage of + V having the same polarity as the toner is applied and the drive electrode 164 to which no applied voltage is applied. Next, as shown in FIG. 3C, + V, which is the same polarity as the toner, is applied to the second drive electrode group below the attached toner by applying the respective applied voltages to the toner in the toner transport direction ( In this example, on the right side, the adjacent third electrode group has -V, which is opposite in polarity to the toner, and the first drive electrode group, which is opposite to the toner transport direction of the second drive electrode, has the same polarity as the toner. Is switched so as to apply + V. As a result, since the charge of the toner and the charge of the drive electrode immediately below the toner have the same polarity, a repulsive force is generated, a floating force is generated for the toner, and the third drive electrode group in the toner transport direction is set to 0. To −V and have the same polarity as the toner, the charge of the third drive electrode group attracts the toner at the upper left, and the charge of the first drive electrode group opposite to the toner transport direction is Since the toner has the same polarity as the toner, the toner on the upper right is repelled, and a rightward driving force is generated in the toner. The friction between the toner and the surface of the developing roller is reduced by the floating force, and the toner moves about one pitch of the drive electrode by the drive force due to the electric charge. Next, as shown in FIGS. 3 (e) and 3 (f), in order to shift the voltage (FIGS. 3 (c) and 3 (d)) of the pattern for repelling and driving the toner by one, Switch the applied voltage. Thereafter, similarly, the toner is continuously moved by applying the drive electrodes one by one while shifting them. Here, Table 1 summarizes the switching of the voltage applied to each drive electrode group from FIG. 3B to FIG. 3F and thereafter. FIG. 3B shows the steps in the table, and FIGS. 3C and 3D show the steps.
FIGS. 3E and 3F correspond to the steps. The steps are + V,-for each of the first to third drive electrode groups.
V and + V are applied, and the voltage of the pattern for repelling and driving the toner is shifted from the step by one to the right in the toner conveying direction. Thereafter, the pattern voltage for performing the repulsion and driving of the toner is shifted one by one by repeating the steps (1) to (4).

[Table 1] 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, the drive can be performed in the opposite direction.

Based on the above operating principle, in the configuration of the present embodiment, the developing devices 16a and 16b are brought into an operating state (a state where a developing operation is being performed) based on a known two-color image forming process. During the operation of each of the developing devices 16a and 16b, 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. . The toner conveyed to the developing roller 161 is conveyed to the surface of the photoreceptor by the first electrostatic actuator conveying member 166a and the second electrostatic actuator conveying member 166b which are driven and used for development. The residual toner on the surface of the developing roller 161 is collected in the developing device. Then, each developing device 16a,
In both cases 16b, after the developing operation, in order to prevent color mixing of the toner on the photosensitive drum, the state is such that the toner does not exist on the second electrostatic actuator conveying member 166b facing the surface of the photosensitive drum. For this purpose, only the second electrostatic actuator conveying member 166b is driven to collect the toner on the member into the developing device. During this time, the first electrostatic actuator transport member 166a is not driven because the toner in the developing device is transported onto the second electrostatic actuator transport member 166b by the driving of the first electrostatic actuator transport member 166a. This is because toner cannot be present on the second electrostatic actuator transfer member 166b facing the drum surface.

As described above, according to the present embodiment, the toner is conveyed without rotating the developing roller 161 by using the electrostatic actuator member, whereby the portion rubbed by the rotation of the developing roller 161 is eliminated. It is possible to prevent the toner that has entered from being stressed and causing toner to stick. Further, since the developing roller 161 does not rotate, the increase in torque and the generation of heat due to the generation of eddy current are suppressed, and the toner in the developing device does not melt. According to the present embodiment, in order to prevent color mixture of the toner on the photoconductor drum, in the conventional image forming apparatus of this type, a configuration is adopted in which the developing device is retracted from the photoconductor surface after the development operation is completed. This is advantageous in that the apparatus can be simplified and downsized. In the above embodiment, two developing devices are arranged so as to be opposed to the surface of the photoreceptor. However, the present invention is not limited to this, and can also be applied to an arrangement in which three or more developing devices are opposed to each other. Further, the present invention can be applied to an image forming apparatus having a plurality of developing devices so that an operator can select a color of a single color image. Further, in an image forming apparatus having only one developing device, wherein the developing device is configured to be detachable from the main body of the image forming apparatus, when the developing device is taken out from the main body of the developing device, the developing device is exposed inside and outside the apparatus. In order to prevent toner from being present on the developing roller portion, the configuration of the developing device of the present embodiment can be used.

[0012]

As described above, according to the present invention, the electrostatic actuator conveying means is used as the developer conveying means of the developing device, whereby toner is supplied onto the latent image carrier. There is no need to rotate the means, and it is possible to eliminate problems such as toner sticking in the developing device and an increase in driving torque. Further, since the toner is conveyed without using a rotating member like a conventional developing roller, the toner is scattered by centrifugal force as in the case of using a rotating member, and the scattered toner stains a transfer device and the like. In addition, the occurrence of an abnormal image, and the problem of poor application of the developing bias voltage due to application of a voltage via a bearing or the like of a member that rotates from a developing bias power source do not occur. Further, the electrostatic actuator transporting means constitutes a toner path for discharging toner from inside the developing device toward the surface of the latent image carrier, and a first electrostatic actuator transporting member which is discharged from the developing device. A second electrostatic actuator conveying member that forms a toner path for collecting toner into the developing device, and during the developing operation, both the first electrostatic actuator conveying member and the second electrostatic actuator conveying member Drive to supply the toner from the inside of the developing device onto the latent image carrier and collect the residual toner after the development into the developing device. When it is necessary to collect the existing toner in the developing device, only the second electrostatic actuator conveying member is driven to be present on the second electrostatic actuator conveying member. It can be recovered toner in the developing device. Therefore, a plurality of developing devices using toners of different colors are arranged on the surface of the latent image carrier, and any one of the developing devices is selectively operated to form a multi-color image. If only the second electrostatic actuator transport member is driven during the switching operation of the above, the color mixing of the toner on the latent image carrier can be prevented without using the moving mechanism of the developer transport means for the latent image carrier. Therefore, the mechanism can be simplified and the positional accuracy of the developer conveying means with respect to the latent image carrier can be improved. Further, in an image forming apparatus in which a single developing device is disposed opposite to the surface of a latent image carrier, when taking out the developing device from the apparatus main body, it is possible to drive only the second electrostatic actuator transport member before the removing operation. For example, it is possible to prevent toner scattering when taking out the developing device with a simple configuration.

[Brief description of the 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. 1;

FIGS. 3A to 3F are explanatory diagrams of a toner conveying operation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 16a first developing device 16b second developing device 161 developing roller 162 charging roller 163 agitator 164 drive electrode 165 stator 166a first electrostatic actuator transport member 166b second electrostatic actuator transport member

Claims (3)

(57) [Claims] An image forming apparatus comprising a developing device for supplying toner onto a latent image carrier to develop a latent image on the latent image carrier, wherein the developing device is used as a developer conveying means of the developing device. A first electrostatic actuator conveying member forming a toner path for discharging toner from the inside toward the surface of the latent image carrier, and a toner discharged from the developing device facing the latent image carrier.
Allowed, and use those having a second electrostatic actuator conveying member constituting the toner path for recovering in the developing device
After the development operation, the first electrostatic actuator transport member
In the non-operation state, the second electrostatic actuator conveying means is moved.
An image forming apparatus, comprising: a drive control means for controlling a drive to operate. 2. The image forming apparatus according to claim 1 , wherein the hopper for storing toner and the toner from the hopper are transferred to the first electrostatic actuator.
A member that contacts and rotates and frictionally charges the member
An image forming apparatus comprising: 3. An image forming apparatus according to claim 1, wherein said electrostatic actuator transport member comprises three adjacent electrodes.
Connected to first to third electrode terminals which are different from each other
The first to third drive electrode groups thus formed are arranged in the transport direction.
And one of the first to third electrode terminals having a polarity opposite to that of the toner.
The other two apply a voltage of a pattern having the same polarity as the toner,
The electrodes to be polarized are shifted one by one in the first to third electrodes
Image shape characterized by applying while switching
Equipment.