JPH0344665A - Developing device - Google Patents

Abstract

PURPOSE:To effectively remove a stagnating developer at good timing by providing an air supplying port in the space between a developing roller and a blade and blowing air when a pressure sensor detects a constant amount of the stagnating developer. CONSTITUTION:The air supplying port 103 is formed in a housing side wall at a position facing the space between the developing roller 11 and blade 18 and an air supplying device 30 is connected thereto through an air hose 29. Further, the pressure sensor 26 which detects development pressure is arranged at a proper position between the blade 18 and developing roller 11. When the stagnating developer D exceeds the constant amount, the pressure detected by the pressure sensor 26 rises and when the pressure exceeds a specific value, air is blown from the supplying port 103 through a controller 28. Consequently, the stagnating developer D is carried out of the machine from a communication port through a flowing-out port and collected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device provided in an image forming apparatus such as a copying machine.

[Conventional technology]

Generally, in a developing device that uses a non-magnetic component type developer, a thin layer forming member such as a blade is pressed against the surface of a developer carrier such as a developing roller with a predetermined pressure, and frictional electrification occurs between the two. By imparting an electric charge to the developing agent, the developing agent adheres to the photoreceptor having a predetermined surface potential, thereby forming a developed image. That is,
The amount of charge of the developer is determined by the contact pressure between the thin layer forming member and the developer carrier, which in turn determines the state of the image.

However, in such a developing device, as the developer gradually accumulates between the thin layer forming member and the developer carrier, the stagnant developer sticks to each other, and the solidified developer is damaged. Due to the interposition, a gap may be created between the thin layer forming member and the developer carrier, and the contact pressure between the two may be reduced. Since such a decrease in contact pressure directly leads to image deterioration, prevention has become a major issue.

Therefore, Japanese Utility Model Application Publication No. 63-101951 proposes a device in which a developer aggregation preventing member made of a bristle brush or the like is provided near the thin layer forming member. This agglomeration prevention member is
It consists of a bristle brush that scrapes off the accumulated developer, and a nozzle that blows air toward the accumulated developer in the direction in which it is supplied.

Furthermore, in Japanese Patent Application Laid-open No. 58-37675, a thin layer forming member (layer thickness regulating means in the same publication) is configured to be able to approach and separate from a developer carrier, and when the number of copies exceeds a predetermined number, In this example, the thin layer forming member is largely separated from the developer carrier, and the accumulated developer is carried to another area while remaining on the developer carrier.

Furthermore, Japanese Patent Application Laid-Open No. 63-118170 discloses a device in which the developer carrier is reversely rotated for a certain period of time or by a certain angle after the end of the development process or before the start of the development process, thereby removing the accumulated developer. It is shown.

[Problems to be Solved by the Invention] The device disclosed in Utility Model Application Publication No. 63-101951 is provided with an agglomeration prevention member in the space formed by the developer carrier and the thin layer forming member, so that it is particularly difficult to prevent bristle brushes, etc. is applicable to devices where the angle between the developer carrier and the thin layer forming member is an obtuse angle or close to a right angle; however, in the case of a device where the angle is small, It is difficult to apply this method because there is no space to install an agglomeration prevention member.

On the other hand, in a structure using a nozzle that sprays air, the air is sprayed in approximately the same direction as the developer supply direction, so that the developer is between the developer carrier and the thin layer forming member. There is a risk that it may spray out and scatter outside. Furthermore, since the amount of developer retained cannot be determined with this device, it is difficult to set the timing for blowing air.

Furthermore, in such an apparatus, there is a possibility that the aggregation prevention member itself may disturb the flow of the developer.

Furthermore, in the case of the device disclosed in Japanese Patent Application Laid-Open No. 58-37675, after the accumulated developer is carried to another area while being carried on the developer carrier, the accumulated developer on the developer carrier is scraped off. This requires a means and a container for storing the scraped developer, and there is a disadvantage that the internal structure of the developing device becomes complicated.

Furthermore, in the apparatus of this publication and the apparatus of JP-A No. 63-118170, not only is it necessary to separately perform the removal process of the stagnant developer in addition to the development process, but also the process of removing the stagnant developer is difficult. After a certain period of time regardless of the amount of developer (
For example, after the development process has been performed a certain number of times), the processing operation may be executed even when there is not much developer accumulated, or the processing operation may be executed even though the developer has accumulated. This makes it difficult to process at the right time.

Furthermore, if a means for setting the contact pressure to a high value is used from the time of assembly and set-up, wear and tear of the thin layer forming member and the developer carrier will be accelerated, and the amount of charge of the developer will be excessive, resulting in an image failure. There is an inconvenience that fogging or the like tends to occur.

In view of these circumstances, it is an object of the present invention to provide a developing device that can effectively remove the developer accumulated between the photoreceptor carrier and the thin layer forming member at an appropriate timing. .

[Means to solve the problem]

The present invention provides a developer carrier disposed near a photoreceptor, and a thin layer forming member that is pressed against the surface of the developer carrier to form a thin layer of developer on the developer carrier. In the developing device, an air supply port opening in a direction substantially perpendicular to the developer supply direction is provided at a position facing the space between the thin layer forming member and the developer carrier, and the air supply port and An air outlet is provided at a separate position to communicate the inside and outside of the developing device, and a developer detecting means detects the developer accumulated in the space, and after the developer detecting means detects a certain amount of developer, the air is The device is equipped with an air supply means for blowing air into the inside of the device from the supply port.

[For production]

According to the above configuration, when a certain amount of developer actually accumulates between the developer carrier and the thin layer forming member, the air supply means supplies the developer from the air supply port toward the accumulated developer. Air is blown in a direction substantially perpendicular to the developer, thereby removing the developer from the stagnant area. At this time, air in the developing device is released from the air outlet, thereby preventing a sudden pressure increase in the developing device due to air supply.

〔Example〕

An embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a developing device installed in an image forming apparatus such as a copying machine, and this developing device includes a housing 10 containing a non-magnetic component developer. The housing 10 is made up of a hopper 13 that accommodates developer and a developer container 14. Inside the developer container 14, a developer roller (developer carrier) 11 and a supply roller 1 are in contact with each other.
2 are arranged. The rotation axes of these rollers 11 and 12 are rotatably supported by both side walls 102 of the housing 10 as also shown in FIG. It is designed to be interlocked and driven in a clockwise direction.

The developing roller 11 is disposed near the photosensitive drum 16, and a blade 18 is disposed on its circumferential surface.

This blade 18 consists of a thin metal plate 20 having flexibility.
The end portion of this metal plate 20 is fixed to an inner plate 101 inside the developer container 14 .

On the other hand, a stepping motor 2 is mounted on the housing side wall 102.
2 is fixed, and the cam 24 is connected to its drive shaft 221.
By pushing down the metal plate 20, the blade 1
The free end of 8 is pressed onto the circumferential surface of the developing roller 11. The rotation of the cam 24 driven by the stepping motor 22 changes the force with which the metal plate 20 is pressed, and the contact pressure between the blade 18 and the developing roller 11 is adjusted.

Further, as a feature of this device, as shown in FIG. 2, a pressure sensor (developer detection means) 26 is incorporated in a proper position on one side wall 102 of the housing. This pressure sensor 26 faces a space surrounded by the circumferential surface of the developing roller 11 and the lower surface of the blade 18, and is located at a position where it comes into contact with the developer when a certain amount of developer has accumulated in this space. The detection signal is manually inputted to a control device (microcomputer; constituting the air supply means) 28 as shown in FIG.

As shown in FIGS. 2 and 3, a portion of both housing side walls 102 located slightly downstream of the pressure sensor 26 in the developer supply direction is provided with A pair of air supply ports 103 opening in the direction are provided. This air supply port 10B
An air supply device (constituting air supply means) 30 consisting of a fan or the like is connected via an air hose 29.
This air supply device 30 blows air into the developing device.

The timing of this air blowing is controlled by the control device 28 described above. Specifically, when the pressure P detected by the pressure sensor 26 exceeds a predetermined value Po, in fact, when the output voltage of the pressure sensor exceeds a certain value, the control device 28 starts supplying air. A control signal is output to the device 30, and the air supply device 30 is activated.

On the other hand, a communication port 104 is provided at a proper location on the inner plate 101 to communicate the upper and lower spaces thereof, and this communication port 104 is provided with a mesh that prevents the scattered developer from passing through.

Furthermore, an air outlet 105 is provided on the top wall of the housing 10 directly above the housing 10 to communicate the inside and outside of the housing 10.

Next, the operation of this developing device and the contents of control performed by the control device 28 will be explained with reference to the flowchart of FIG. 4.

First, every time the copying machine performs a copying operation, a developing device performs a developing process (step S1). Specifically, the developing roller 11 and the supply roller 12 are rotationally driven in the counterclockwise direction in FIG. At the contact portion between the supply roller 12 and the development roller 11, a slight amount of frictional electrification causes the developer to be charged (a negative charge in this embodiment).

This developer layer adheres to the circumferential surface of the developing roller 11 and is conveyed to the photosensitive drum 16 side, and this developer layer is formed into a thin layer at the contact area between the circumferential surface of the developing roller 11 and the blade 18. At the same time, it is even more strongly triboelectrically charged and adheres to the circumferential surface of the photoreceptor drum 16, which has been given a positive surface potential in advance, thereby forming a developed image on the photoreceptor drum 16.

When such a developing process is repeated many times, a developer accumulates between the blade 18 and the circumferential surface of the developing roller 11, as shown in FIG. 1, and the amount thereof gradually increases. and,
When the amount of accumulated developer exceeds a certain amount, this amount of accumulated developer begins to come into contact with the pressure sensor 26 (double-dashed line in FIG. 1), and the pressure P detected by the pressure sensor 26 increases, and the amount of the accumulated developer increases. Due to the presence of the agent, the contact pressure between the blade 18 and the developing roller 11 begins to decrease.

Here, when the detected pressure P exceeds the predetermined EnPo (YES in step S2), a control signal is output from the control device 28 to the air supply device 30, and the air supply device 30
Air is blown onto the accumulated developer through two air hoses and the air supply port 103 in a direction perpendicular to the direction in which the developer is supplied (step S3). As a result, the accumulated developer is blown away from the place where it has accumulated, and the blade 1
The contact pressure between the developing roller 8 and the developing roller 11 is maintained appropriately.

In addition, the amount of air corresponding to the supplied air is
4 to the outside of the apparatus through an air outlet 105, thereby preventing the pressure inside the developing apparatus from increasing.

As described above, this device actually detects the developer accumulated between the blade 18 and the developing roller 11, and blows air against the developer at an appropriate timing based on the detection result. Therefore, accumulated developer residue, which causes image deterioration, can be effectively removed at an appropriate timing. Moreover, since the air is sprayed from the direction perpendicular (to the side) to the developer supply direction (rotation direction of the developing roller 11), it is difficult to install the air supply means in the developing device. There is no need to secure a space, and there is no fear that developer particles will be scattered outside the apparatus through the gap between the blade 18 and the developing roller 11 due to the air. However, in the present invention, the direction of air blowing and the developer supply direction do not need to be exactly at right angles.

Here, if the inside of the developing device is completely sealed like a normal device, the pressure will rise rapidly due to the supply of air, and there is a risk that the developer inside the device will spray out and scatter outside through the gap. By providing the air outlet 105, pressure increase can be prevented, and by providing the mesh in the communication port 104, the blown developer can be prevented from scattering to the outside from the air outlet 105. .

Note that the present invention is not limited to such embodiments, and may take the following embodiments as examples.

(1) In the present invention, any suitable air supply means, such as a fan or a compressor, may be used regardless of the type of air supply means. Further, the circuit may be configured so that the air supply means is operated directly by a detection signal from the developer detection means without using a microcomputer.

(2) In the above embodiment, the inner plate 101 is provided with a mesh-filled communication port 104, and the air outlet 105 is provided above it. However, if the inner plate 104 etc. are not provided, A mesh or the like may be provided at the air outlet to block the developer.

Also in this case, if the air outlet is provided at a position where the scattered developer cannot reach, there is no particular need to provide the mesh or the like.

(3) In the present invention, the air supply port 103 may be provided only on one side wall 102 of the housing in the device of the above embodiment, regardless of the number of air supply ports and the number and arrangement location of the air outlet ports. good. In this case, by providing an air outlet on the other opposing housing side wall 102, air circulation is improved and the removal effect is enhanced.

(4) In the present invention, other types of sensors such as a photosensor may be used in addition to the pressure sensor described above, regardless of the specific structure of the developer detection means. For example, when using a photosensor, as shown in FIG.
02, and the other housing side wall 1.
By incorporating the light-receiving cable 32 into 02, it is possible to detect the presence or absence of developer D accumulated between the two.

(5) In the present invention, there is no particular need for the thin layer forming member to be configured to be able to adjust the contact pressure with respect to the developer carrier. is possible.

〔Effect of the invention〕

As described above, the present invention actually detects the developer accumulated between the thin layer forming member and the developer carrier, and blows air to the accumulated developer at a timing based on the detection result. Therefore, the stagnant developer that causes image deterioration can be effectively removed at an appropriate timing. Moreover, since the air is blown in a direction substantially perpendicular to the direction in which the developer is supplied, there is no need to provide an air supply means inside the device, and the installation space can be secured reliably. There is no fear that the agent will scatter to the outside of the apparatus from the gap between the thin layer forming member and the developer carrier.

Further, since an air outlet is provided that communicates the inside and outside of the developing device, it is possible to prevent the developer in the device from being ejected to the outside from the gap due to a sudden pressure increase due to air supply.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional side view of a developing device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, FIG. 3 is a side view showing the main parts of the device, and FIG. 5 is a flowchart showing the developer removal operation performed in the developing device, and FIG. 5 is a sectional view corresponding to FIG. 2 of the developing device in another embodiment. D...Developer, 11...Developing roller (developer carrier) 16...Photosensitive drum, 18...Blade (thin layer forming member), 26...Pressure sensor (developer detection means) )
, 28...control device (air supply means), 30...air supply device, 31...light emitting element (developer detection means),
32... Light receiving element (developer detection means).

Claims (1)

[Claims] 1. A developer carrier disposed near the photoreceptor, and a thin layer forming member that is pressed against the surface of the developer carrier to form a thin layer of developer on the developer carrier. In the developing device, an air supply port opening in a direction substantially perpendicular to the developer supply direction is provided at a position facing the space between the thin layer forming member and the developer carrier, and an air supply port is provided at a position different from the air supply port. An air outflow port communicating between the inside and outside of the developing device is provided, and a developer detection means detects the developer accumulated in the space, and after the developer detection means detects a certain amount of developer, an air outlet is provided from the air supply port. A developing device comprising an air supply means for blowing air into the inside of the device.