JP2774656B2 - Developer stirring device for image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] Development of an image forming apparatus such as an electrophotographic apparatus in which an electrostatic latent image formed on the surface of a photoreceptor is developed with a developer composed of a chargeable fine powder. With regard to the developer agitator, the developer is agitated in accordance with the amount of charge, and the purpose is to control the amount of charge of the developer within a certain range. ,
A developer stirring means for stirring the developer in the developing device, a developer flow pressure detecting means for detecting a pressure of the flow of the developer in the developing device, and a developer flow pressure detecting means. A stirring control means for receiving a detection signal and outputting a control signal for controlling the operation of the developer stirring means.

[Industrial applications]

The present invention relates to a developer agitator of an image forming apparatus such as an electrophotographic apparatus in which an electrostatic latent image formed on a surface of a photoreceptor is developed with a developer made of a chargeable fine powder.

A so-called two-component developer in which a toner and a carrier are mixed is widely used as a developer for an electrophotographic apparatus or the like. Charge.

[Conventional technology]

Generally, an agitator called an agitator is provided in the developing device containing the developer, and the agitator is rotated by a motor to agitate the developer. This agitator has been conventionally driven at a uniform rotational speed.

[Problems to be solved by the invention]

To obtain stable development, it is necessary to control the charge of the toner within a certain range. What affects the charging of the toner is the appropriate stirring of the developer and the state of the flow of the developer.

If the agitation of the developer is poor, the charge amount of the toner becomes small, which causes stain on the background portion. On the other hand, if the developer is agitated too much, the charge amount of the toner increases, the flow of the developer deteriorates, the amount of the developer sent to the developing unit decreases, and the print density decreases. Further, the charge amount of the toner also changes due to a change in environment.

Therefore, in order to maintain the charge amount of the toner in an appropriate state, it is desirable to agitate the developer in accordance with the state of the flow of the developer in the developing device. It is necessary to grasp quantitatively.

However, in the past, there was no small sensor capable of quantitatively detecting the flow of the developer in the developing device, and only the agitator was rotated uniformly. Could not keep in condition.

The present invention solves such a conventional drawback and provides a developer stirring device for an image forming apparatus capable of controlling the charge amount of the developer within a certain range by stirring the developer according to the charge amount. The purpose is to provide.

[Means for solving the problem]

In order to achieve the above object, the developer stirring device of the image forming apparatus of the present invention accommodates a developer composed of a finely-charged powder as shown in FIG. 1 for explaining the embodiment. A developing device 1; a developer stirring device 2 for stirring the developer in the developing device 1; and a developer flow pressure detecting device 3 for detecting the pressure of the flow of the developer in the developing device 1. A stirring control means 4 for inputting a detection signal from the developer flow pressure detecting means 3 and outputting a control signal for controlling the operation of the developer stirring means 2.

Note that, as the developer flow pressure detecting means 3, a polymer piezoelectric element in which a polymer piezoelectric material is formed in a thin film shape can be used.

[Action]

The flow pressure of the developer in the developing device 1 is detected by the developer flow pressure detecting means 3, and the operation of the developer stirring means 2 is controlled by the stirring control means 4 according to the detection signal.

Further, since the polymer piezoelectric element is flexible and has good workability, the developer flow pressure detecting means 3 is formed smaller than a fragile and difficult-to-work material such as quartz or ferroelectric ceramic. can do.

〔Example〕

 Embodiments will be described with reference to the drawings.

FIG. 1 shows a configuration of a printer to which the present invention is applied. The present invention is not limited to printers, but can be widely applied to copiers and other electrophotographic devices.

In FIG. 1, reference numeral 21 denotes a photosensitive drum which is charged to a predetermined potential and transfers image information to be transferred onto the paper 100 to the outer peripheral surface and rotates in the direction of arrow A. A charger 22 charges the photosensitive drum 21 to a uniform predetermined potential.

A photosensitive unit 23 for exposing characters, figures, and other images on the surface of the photosensitive drum 21 is provided between the charger 22 and the developing unit 1.
Are provided, and a laser beam scanning device, an LED array, and the like are provided.

25 is a paper feed roller. A transfer unit 26 for transferring the toner image formed on the surface of the photosensitive drum 21 to the printing paper 100 is provided at a contact portion between the printing paper 100 and the photosensitive drum 21. 27 is the printing paper 100 on which the toner image is transferred
A fixing roller for heating the image to fix the image. 28 is
This is a cleaning unit for cleaning and removing toner and the like remaining on the surface of the photosensitive drum 11.

In the upper part of the developing device 1, a two-component developer (hereinafter, referred to as a toner) composed of a charged colored fine powder and a carrier is mixed.
A hopper 11 for replenishing the developer (hereinafter simply referred to as “developer”) is provided, and the developer in the hopper 11 is dropped into the developing device 1 by the rotation of the replenishment roller 12.

A stirrer 2 composed of a motor and an agitator rotated by the motor is provided in the developing device 1. An opening formed toward the photosensitive drum 21 has a photosensitive drum 21.
A developing roller 13 for developing the electrostatic latent image formed on the surface of the toner image 21 with toner is disposed.

The agitator 2 and the developing roller 13 rotate as shown by arrows B and C, whereby the developer in the developer 1 is moved by arrows d, e,
Flows like f.

14 is a flow regulating plate for regulating the flow of the developer. Reference numeral 15 denotes a blade for scraping off a portion of the developer adhered to the surface of the developing roller 13 and conveyed to the developing section, the portion being thicker than a certain layer thickness.

In the vicinity of the bottom of the developing device 1, a polymer piezoelectric plate 3 for detecting the pressure of the flow of the developer is provided with a developing roller 13 and a stirrer 2.
It is arranged at a position near between. However, the position of the polymer piezoelectric plate 3 may be any position as long as it is suitable for detecting the pressure of the flow of the developer in the developing device 1.

Further, only one polymer piezoelectric plate 3 may be provided at an intermediate position in the axial direction of the photosensitive drum 21 or a plurality of polymer piezoelectric plates 3 may be provided along the axial direction. The control may be performed based on the average value of the detection values of the plurality of polymer piezoelectric plates 3.

Furthermore, the polymer piezoelectric plate 3 may be disposed so that the plate surface is inclined at about 45 degrees with respect to the direction of flow of the developer, or a flange plate or the like is attached to the bottom plate of the developing device 1 and affixed thereto. You may wear and fix.

FIG. 2 schematically shows the structure of the polymer piezoelectric plate 3, and FIG.
Is a piezoelectric element (piezoelectric dielectric) formed of a thin film of, for example, a vinylidene fluoride-based polymer piezoelectric material, and 32 is a piezoelectric element
Electrodes 33 provided on both sides of 31 are output terminals connected to each electrode 32.

By applying pressure or tension to the polymer piezoelectric plate 3,
When stress of expansion or contraction or stress of displacement is applied, the piezoelectric element
A polarization charge 30 is generated in 31, and a potential corresponding to the stress is detected at output terminal 33.

Returning to FIG. 1, reference numeral 4 denotes a control unit which receives an output voltage from the polymer piezoelectric plate 3 and controls the rotation of the motor of the stirrer 2. In the control unit 4, when the input potential from the polymer piezoelectric plate 3 increases, the rotation of the stirrer 2 is increased,
Conversely, when the input potential from the polymer piezoelectric plate 3 decreases, the rotation of the stirrer 2 is slowed.

Therefore, when the charge amount of the developer becomes too small and the flow of the developer becomes faster, the rotation speed of the stirrer 2 increases and the charge amount of the developer increases, and conversely, the charge amount of the developer increases. When the flow of the developer is slowed down due to excessive rotation, the rotation speed of the stirrer 2 is reduced, and the charge amount of the developer is reduced. In this way, the charge amount of the developer is always controlled within an appropriate range.

In the above embodiment, a two-component developer is used as a developer, but the present invention is not limited to this, and a one-component developer or another developer may be used.

〔The invention's effect〕

According to the developer stirring device of the image forming apparatus of the present invention, the operation of the developer stirring means is controlled by detecting the pressure of the flow of the developer in the developing device, whereby the charge amount of the developer is always kept constant. Since it can be controlled within a certain range, there is an excellent effect that a stable high-quality image can be obtained.

Further, by using the polymer piezoelectric element, the developer flow pressure detecting means can be easily configured in a small size, and can be disposed in the developing device without any trouble.

[Brief description of the drawings]

 FIG. 1 is a schematic view of the configuration of a printer according to the embodiment, and FIG. 2 is a schematic view of the configuration of a polymer piezoelectric plate of the embodiment. In the figure, 1 ... developing device, 2 ... developer stirring means, 3 ... developer flow pressure detecting means, 4 ... stirring control means.

Continuation of front page (56) References JP-A-2-7077 (JP, A) JP-A-53-143337 (JP, A) JP-A-63-19231 (JP, U) (58) Fields investigated (Int .Cl. ⁶ , DB name) G03G 15/08 G03G 15/00 303 G03G 13/10 G03G 15/10

Claims (2)

(57) [Claims] 1. A developing device (1) containing a developer composed of a charged fine powder, a developer stirring means (2) for stirring the developer in the developing device (1), A developer flow pressure detecting means (3) for detecting the pressure of the flow of the developer in the developing device (1); and a detection signal input from the developer flow pressure detecting means (3), and A developer stirring device for an image forming apparatus, comprising: a stirring control device (4) for outputting a control signal for controlling the operation of the stirring device (2). 2. A developer agitator for an image forming apparatus according to claim 1, wherein a polymer piezoelectric element in which a polymer piezoelectric material is formed in a thin film shape is used as said developer flow pressure detecting means (3). apparatus.