JP2004163822A - Development device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer conveyance means for steadily collecting information about developer in a developer container, for example, the amount of developer remaining in it. <P>SOLUTION: In the development device including a developer conveyance member for supplying developer to a developer carrier and a detection means for detecting information about developer in a development container, the developer conveyance member has a structure for conveying developer in a direction besides the direction of the developer carrier, and at least one of the developer conveyance directions thereby generated is a direction in which the detection means is disposed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as an electrophotographic apparatus, which includes a developing device used when developing an electrostatic latent image formed on an image carrier.
[0002]
[Prior art]
In a conventional image forming apparatus such as an electrophotographic apparatus, as shown in FIG. 9, a photoconductor 201 as an image carrier is provided, and a primary charger, an exposure device, and the like (not shown) are provided on the photoconductor 201. An electrostatic latent image is formed by a developing device 202, and a developer is adhered to the electrostatic latent image by a developing device 202 to form a visible image. Then, the visible image is transferred by the transfer device 209 to the transfer material S stored in the paper feed cassette 203 and supplied to the photoconductor 201 via the paper feed roller 205, the transport rollers 206 and 207, and the like. The sheet is conveyed to the fixing device 211 by the conveying device 210 together with the material S, and is fixed on the transfer material S by being heated and pressed by the fixing device 211 to form a permanent image. Is discharged as.
[0003]
Therefore, in the image forming apparatus having such a configuration, the developing device 202 needs a developing sleeve 202b for attaching the developer to the electrostatic latent image on the photoconductor 201 and a developing container 202a for storing the developer. Further, as the image formation is repeated, the developer in the developing container 202a is sequentially consumed, and the remaining amount of the developer in the developing container 202a decreases. Need to be replenished.
[0004]
Since the replenishing operation of the developer to the developing device 202 is troublesome and involves the scattering of the developer, it is preferable to reduce the number of times as much as possible. A developer developing buffer (hereinafter referred to as a developing buffer) 212 is provided above the developing device 202.
[0005]
The developing buffer 212 is formed to be large enough to accommodate a large amount of developer, and the developer can be automatically replenished sequentially from the developing buffer 212 to the developing container 202a of the developing device 202. The number of complicated developer replenishment operations performed by hand is greatly reduced.
[0006]
Further, a developer cartridge 213 as a developer replenishing container that is detachable from the developing buffer is provided above the developing buffer, so that the developing buffer can be replenished with the developer.
[0007]
As described above, in order to automatically supply the developer, a sensor capable of detecting the presence or absence of the developer is attached to the developer container on the side that receives the developer. In the present image forming apparatus, a piezo sensor is attached to the side wall of the developing container as indicated by 214 in the figure, and the presence or absence of the developer is determined based on the level of the developer detection signal from the sensor.
[0008]
FIG. 3 is a sectional view of the developing device in the vicinity of the piezo sensor 214. In the figure, for simplicity, a state in which the developer covering each member is removed is shown. In general, a cleaning spring 215 having one end of a compression spring extended on an arm is arranged in the vicinity of the piezo-type sensor so that the developer is not fixed to the detection surface of the sensor, and the sensor surface is always cleaned. . The cleaning spring is wound around a shaft end of a developer conveying member 216 for conveying the developer to a developing sleeve (not shown), and rotates at a constant interval on the sensor surface in conjunction with the rotation of the conveying member in the direction of the arrow in the drawing. Rub with An extension 216 is formed by extending one end of the transport member in order to make the transport amount of the developer to the developing sleeve side by the transport member uniform in the longitudinal direction.
[0009]
[Problems to be solved by the invention]
However, for example, when an image forming apparatus such as a conventional example is installed in an environment having a large amount of moisture in the air such as a high-temperature and high-humidity environment, and an image having a relatively small image duty is formed, the developer in the developing device The following phenomena occur because the fluidity of the toner deteriorates and the consumption of the developer is small.
[0010]
FIG. 10 is a view of the vicinity of the piezo sensor inside the developing device 202 from the direction of arrow D in FIG. The figure shows a state in which the uniformity of the development conveyance amount in the longitudinal direction of the container is broken and the developer near the side surface of the container is discharged first, that is, so-called “hollowing” occurs.
[0011]
The above-mentioned piezo sensor 301 is attached to the side of the container and monitors the presence or absence of the developer in the developing device. Therefore, if the developer near the side of the container is discharged first, an image is output from the piezo sensor. A signal indicating that the developer is “absent” is transmitted to the control unit of the forming apparatus main body, and the developer is supplied from the developing buffer even though the developer is sufficiently supplied to portions other than the end of the developing container. Will be supplied.
[0012]
Then, the filling density of the developer in the developing container is further increased, an excessive load is applied to the stirring member, and an accident such as damage to the stirring member or breakage of a gear for driving the stirring member occurs. I will.
[0013]
In view of the above, an object of the present invention is to provide a developer conveying unit for stably collecting information on a developer such as a remaining amount of the developer in a developing container. For example, an image forming apparatus is installed. A means is provided for stabilizing the state of the developer in the developing device against disturbances such as environment, image ratio at the time of image formation, and image density.
[0014]
[Means for Solving the Invention]
According to the present invention, a developer carrying member arranged to face an image carrying member, a developer carrying member for supplying a developer to the developer carrying member, an image carrying member, and a developer carrying member are provided. In a developing device including a developing container to be housed and a detecting unit for detecting information about the developer in the developing container, the developer conveying member has a configuration for conveying the developer in a direction other than the developer carrier direction, The object is achieved by at least one of the resulting developer transport directions being a direction in which the detection unit is disposed.
[0015]
Further, the above object is also achieved by the constitution in which the developer conveying member has a rotation center support shaft for rotating in one direction and, at the same time, a screw-shaped member is integrally arranged on the rotation center support shaft. be able to.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic side view of a main part of the image forming apparatus, which will be briefly described.
[0017]
The surface photosensitive layer of the rotating cylindrical photosensitive drum 1 extending in the direction perpendicular to the paper in the apparatus main body is uniformly charged by the primary charger 2. Reference numeral 3 denotes a laser scanner that modulates an image signal input to the image forming apparatus to turn on / off a laser beam. A laser beam 4 indicated by a dashed line emitted from the laser scanner is projected on the charged surface, and an electrostatic latent image is formed on the surface of the photosensitive drum.
[0018]
When this latent image reaches the developing site where the developing device 5 is located with the rotation of the photosensitive drum 1, the latent image is visualized by the developer supplied from the developing device to the latent image, and the developer image is formed. Become. With the further rotation of the photosensitive drum, the developer image reaches a transfer site where the photosensitive drum and the transfer charger 6 are opposed to each other.
[0019]
At the same time, the transfer material S is supplied to the transfer portion via the registration roller 11 in synchronization with the timing of the developer image. In this embodiment, a state in which the transfer material S is fed from the manual feed unit 12 is shown. Next, a transfer bias is applied to the transfer charger, and the developer image on the photosensitive drum side is transferred (transferred) to the transfer material.
[0020]
After the end of the transfer, a separation current is applied to the transfer material from the separation charger 13, the transfer material is separated from the photosensitive drum, reaches the fixing device 15 via the transport path 14, and the developer image is fixed and fixed to the transfer material. After that, it is discharged outside the machine.
[0021]
At the time of transfer, a little transfer residual developer remaining on the photosensitive drum without being transferred to the transfer material proceeds as it is, reaches the position of the cleaner 16, and is removed by the cleaning blade 17. Further, the residual charges are erased by the pre-exposure lamp 18, and the photosensitive drum is ready for the next image forming step.
[0022]
Next, the developing device of the present image forming apparatus will be described in detail with reference to FIG. The developing device of the present embodiment has three units as a whole. A developing container 21, a developing buffer 22, and a developer cartridge 23;
[0023]
In the developer cartridge, there is a stirring blade 31 for stirring the developer contained therein and for preventing the developer from remaining on the inner wall, and circulates in the arrow direction in the drawing. Below the stirring blade, a screw 32 extends from the near side to the far side in the direction perpendicular to the paper surface, and rotates, thereby conveying the developer agitated and dropped by the stirring blade from the near side to the far side.
[0024]
FIG. 3 shows the configuration of the developer cartridge and the development buffer viewed from the direction of arrow A. In other words, the developer is supplied from the developer cartridge 41 to the developing buffer 42 through the connection port 43 provided at the longitudinal end of the developing buffer, and the developer is supplied from the developing buffer to the developing container 44 by the developing container. In the entire longitudinal direction.
[0025]
In this way, by supplying the developer from the longitudinal end of the developing buffer, the developer is transferred from the developer cartridge to the developing buffer even for the developer composed of highly fluid ultrafine particles. At the time of replacement or after the transfer of the developer, a large amount of the developer is not scattered even immediately after the developer cartridge is removed from the development buffer. That is, the scattered developer does not contaminate the installation environment of the machine, the operator, as well as members in the apparatus main body.
[0026]
In the present embodiment, as shown in FIG. 3, a conveying means 45 constituted by a screw or the like is provided in the developer cartridge, and the developer is replenished in a short time.
[0027]
When the developer is supplied from the longitudinal end of the developing buffer in this manner, the developer distribution in the longitudinal direction of the developing buffer may be non-uniform, but as shown in FIG. A developer leveling means (hereinafter, referred to as a leveling means) 50 as a stirring means is provided therein, and the developer is supplied from the developing buffer to the developing container over the entire region in the longitudinal direction of the developing container. Therefore, the distribution of the developer in the longitudinal direction becomes uniform, and no image defect occurs.
[0028]
In the image forming apparatus of the present embodiment, the discharge from the developer cartridge can be stopped by the shutter 33 as shown in FIG. The shutter 33 is configured to be linked with the attachment / detachment of the developer cartridge or to be opened and closed by a solenoid or the like.
[0029]
Next, the leveling means provided in the developing buffer will be described. As shown in FIG. 3, since the developer sent from the connecting portion 43 is sent to the end in the longitudinal direction, the developer is merely peaked near the end 50a as it is. Therefore, in the present embodiment, by operating the leveling means 50, the developer at the end is made uniform over the entire area in the longitudinal direction.
[0030]
In this embodiment, the leveling means in the developing buffer is provided with an oval leveling means portion 51 and a screw type leveling means portion 52.
[0031]
As shown in FIG. 4, the oval-shaped smoothing means has a plurality of elliptical plates 53 each having an opening in the surface, and a plurality of elliptical plates 53 are attached to the shaft 54 at an inclined angle. However, the effect of spreading the developer over the entire area while rotating can be obtained.
[0032]
As described above, according to the image forming apparatus of the present embodiment, the inside of the developing buffer can always be uniformly leveled in the entire longitudinal direction by the oval leveling means. Further, since the developer is excellent in stirring ability, the developer can be stirred even if the developer hardens.
[0033]
The screw leveling means includes a screw leveling means 55 of a screw-shaped member having a capability of transporting the developer in the direction B (a direction in which the length is uniform) in FIG. 3 and an ability to transport the developer in the direction opposite to the direction B. And a screw leveling means 56 of a screw-shaped member having
[0034]
The screw leveling means is provided at a supply port of the development buffer through which the developer from the developer cartridge is sent into the development buffer.
[0035]
Here, the screw leveling means conveys the developer in the direction opposite to the direction B, so that the developer near the screw leveling means impairs the uniformity of the developer as compared with other longitudinal portions. Can be avoided.
[0036]
Next, the shutter roller 34 of FIG. 2 will be described with reference to an enlarged view of FIG. When the shutter roller 60 rotates in the direction of arrow C, the developer that has entered the gap t between the developing buffer container 61 and the roller 60 moves with the rotation. When the developer further moves, the developer is conveyed to the developing container by a difference between t and s due to a gap s (t> s) between the container and the roller 60.
[0037]
The developer in the developing buffer is uniformly supplied to substantially the entire longitudinal direction of the developing container through the connection port 35 provided over substantially the entire longitudinal direction of the developing container, so that occurrence of image defects and the like can be prevented. .
[0038]
The shutter roller is operated by an electric signal from a piezo-type developer detecting unit in the developing container, and controls the amount of the developer in the developing container to be equal to or more than a predetermined amount.
[0039]
Next, the configuration of the developing container will be described. Three developer conveying members for gradually supplying the developer to the developing sleeve side are arranged in the developing container. These are a first transport member 36, a second transport member 37, and a third transport member 38 from the side closer to the developing sleeve, and the number of these transport members is the outer diameter of the sleeve, the number thereof, and the developer required for the developing container. The capacity of the image forming apparatus is roughly determined from the capacity of the image forming apparatus. However, the image forming apparatus of the present embodiment is assumed to have a high productivity of one component of black and white, and requires a large capacity. Up to the developer transport member.
[0040]
A piezo sensor 70 is disposed on the side of the developing container near the second transport member to detect the remaining amount of the developer in the developing container. Further, a cleaning spring 71 for extending one end of the compression spring on the arm and cleaning the vibrating part of the piezo sensor is attached to the end of the second transport member on the side of the piezo sensor.
[0041]
Each of the first to third transport members rotates in the direction of the arrow in the drawing, and makes the developer uniformly supplied from the developing buffer portion in almost the entire longitudinal direction reach the developing sleeve 80. The developing sleeve is rotatably supported by a ball bearing (not shown). The developing sleeve rotates in the direction of the arrow in the figure. The developer is thinned by the knife edge blade 81 and is uniformly coated on the developing sleeve. The developer on the surface of the developing sleeve makes a latent image on the photosensitive drum visible at a developing point close to the photosensitive drum 82.
[0042]
6 to 8 are views of the vicinity of the second transport member in FIG. 2 as viewed from the arrow D side. 6 to 8, the developer is schematically shown for simplicity. The second transporting member 100 includes a transporting portion 101 for transporting the developer in a direction not perpendicular to the rotation center axis, ie, a developing sleeve side (not shown) located on the back side in the drawing, and a screw portion on the central shaft body of the transporting member. 102 is integrally formed.
[0043]
103 is a piezo sensor for detecting the presence or absence of the developer. In the vicinity of the piezo-type sensor, a cleaning spring 105 having one end 104 of a compression spring extended in an arm shape is arranged so that the developer is not fixed to the detection surface of the sensor, and the conveying member is provided with a cleaning spring 105 in the direction indicated by an arrow in FIG. The cleaning spring always cleans the sensor surface 106 in conjunction with the rotation in the direction of transport to the developing sleeve on the back side of the drawing. The cleaning spring is wound around the shaft end 107 of the second transport member, and the other end 108 of the arm is hooked on the spindle 109 of the second transport member. These components are the same as the known piezo sensor surface cleaning means.
[0044]
Further, in order to equalize the amount of the developer transported to the developing sleeve side by the transport member in the longitudinal direction, an extended portion 110 is formed by extending one end of the transport member. It is.
[0045]
FIG. 6 shows the powder level of the developer in a normal developing container.
[0046]
However, for example, if the piezo-type sensor in the figure detects the "absence" state of the developer in a state where the image forming operation in which the consumption of the developer is low is continuous, the supply amount of the developer from the developing buffer is in an oversupply state. As shown in FIG. 7, the powder level of the developer in the developing container gradually increases.
[0047]
Eventually, the screw portion on the central shaft of the conveying member also becomes buried in the developer. In this state, the developer conveyance force is generated in the direction of the arrow in the figure parallel to the axis.
[0048]
As a result, as shown in FIG. 8, the exchange of the developer occurs in the direction of the arrow (a) at the end of the developing container, and the fluidity of the developer in this portion is increased, and the height of the powder surface of the developer is increased. Can be kept substantially equal in the longitudinal direction.
[0049]
In response to this phenomenon, if the proper pitch, number of turns, outer diameter, etc. of the screw portion are selected, for example, a piezo sensor which has conventionally been a problem even in a high-temperature and high-humidity environment where the fluidity of the developer is significantly deteriorated "Cavitation" of the developer on the surface can be avoided.
[0050]
【The invention's effect】
As described above, according to the present invention, there is provided a developing device including: a developer conveying member for supplying a developer to a developer carrying member; and a detecting unit for detecting information about the developer in the developing container. The developer transport member has a configuration for transporting the developer in a direction other than the developer carrier, and at least one of the developer transport directions generated thereby is a direction in which the detection unit is arranged. Has a rotation center support shaft for rotational movement in one direction, and at the same time, a developer conveying member having a configuration in which a screw-shaped member is integrally disposed on the rotation center support shaft, so that the detection means Detection accuracy can be improved.
[Brief description of the drawings]
1 is an overall schematic view of an embodiment of the present invention; FIG. 2 is an explanatory view of an embodiment of the present invention; FIG. 3 is an explanatory view of an embodiment of the present invention; FIG. 4 is an explanatory view of an embodiment of the present invention; FIG. 5 is an explanatory diagram of an embodiment of the present invention. FIG. 6 is an explanatory diagram of an embodiment of the present invention. FIG. 7 is an explanatory diagram of an embodiment of the present invention. FIG. 8 is an explanatory diagram of an embodiment of the present invention. FIG. 10 is an explanatory diagram of a conventional example. FIG. 10 is an explanatory diagram of a conventional example.
37, 100 Developer transport member 70, 103 Piezo sensor 101 Transport section 102 Screw

Claims (4)

A developer carrying member arranged to face the image carrying member,
A developer transport member for supplying the developer to the developer carrier,
An image carrier, a developer container containing a developer transport member,
A detecting device for detecting information about the developer in the developing container;
The developer transport member has a configuration for transporting the developer in a direction other than the developer carrier direction, and at least one of the developer transport directions generated thereby is a direction in which the detection unit is disposed. Developing device. 2. The developer conveying member according to claim 1, wherein the developer conveying member has a rotation center support shaft for rotating in one direction, and a screw-shaped member is integrally disposed on the rotation center support shaft. Developing device. The developing device according to claim 1, wherein the detecting unit is a sensor for detecting whether or not the developer is present in the developing container in a predetermined amount or more. The developer is a two-component developer composed of a toner component containing a resin as a binder as a main component and a carrier component containing a magnetic material as a main component, and the detecting unit determines a composition ratio of the toner component and the carrier component. The developing device according to claim 1, wherein the developing device is a sensor for detecting.

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