JPH01100577A - Developing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a developing device, and more particularly, to a developer carrier that holds a one-component developer and transports it to a developing area, and a developer carrier that supplies toner to the developer carrier. The present invention relates to a developing device including a developer supplying member.

(Prior art #: I) In a developing device of an electrostatic recording device that performs development using a one-component developer (hereinafter referred to as toner), a latent image carrier such as a photoreceptor drum on which a latent image is formed. A developer carrier made of a metallic cylindrical developing sleeve or the like is provided so as to be in contact with and rub against the developer carrier. A developer supply member formed from a body or the like is provided so as to come into contact with and rub against the developer supply member. First, when the toner stored in the developer hopper is supplied to the nip formed between the developer carrier and the developer supply member, the toner is rubbed and charged by friction. The developer is deposited on the surface of the developer carrier while being processed, and is further thinned by a developer regulating member formed from a blade, etc., and then transported to a developing area and supplied to the latent image on the latent image carrier. , development is carried out.

However, in such a general one-component developing device, the toner adhesion amount (M/A) changes over time as the number of copies changes, and as a result, the image density (1, D)
There is a problem that the value also changes greatly. The reason for this is that toner with a small particle size passes through the developer regulating member more easily, so during development, the toner with a small particle size is consumed first, and the particle size of the toner particles on the developer carrier gradually increases. It is thought that as the toner particles become larger, the amount of charge (Q/M) on each side of the toner particles decreases, thereby increasing the image density.

(Objective) Therefore, an object of the present invention is to provide a developing device that has a simple configuration and is capable of constantly maintaining a constant image density regardless of changes in toner particle diameter over time.

(Structure) In order to achieve the above object, the present invention includes a developer carrier that holds a one-component developer and transports it to a development area, and a developer supply member that supplies toner to the developer carrier. In the developing device, a developer scraping member for removing developer remaining on the developer carrier after development is provided between the developing area and the developer supplying member, and the developer scraping member removes the developer remaining on the developer carrier after development. A bias voltage is applied to the scraping member to inject charges for developer adsorption to the developer carrier side.

In the developing device having such a configuration, after the development is completed, the developer remaining on the developer carrier is removed by the developer scraping member based on mechanical or electrical scraping force. removed from above. At the same time, a charge for developer adsorption is injected into the developer carrier from the developer scraping member, and the surface portion of the developer carrier is charged with the bias voltage applied to the developer scraper. In other words, the potential is placed on the toner adsorption side.

Next, toner is properly supplied from the developer supply member to the developer carrier which has been brought into the toner adsorption potential state based on the toner adsorption potential, and the toner is deposited on the surface of the developer carrier. attached. At this time, the bias voltage applied to the developer scraping member is fluctuated and controlled in response to the change in toner particle diameter over time, that is, the amount of toner charge over time, and the amount of charge injected into the developer carrier side is changed. If this is done, the amount of toner supplied can be controlled to an appropriate amount so that the image density is always constant. In this case, if the developer supply member side is grounded, the charge remaining on the developer carrier after passing through the developer supply member can be removed. It is possible to operate in the same manner as in the initial state without any image density, and image density fluctuations can be avoided. Furthermore, even if the toner supply amount is directly changed by variable control of the toner supply bias voltage applied to the developer supply member, the toner supply amount is adjusted to an appropriate level so that the image density is always constant. can be controlled.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The figure shows a developing device using a non-magnetic one-component developer as an embodiment of the present invention.

In the figure, a developing sleeve 1 serving as a developer carrier is rotatably supported, and in this example, is rotated at a predetermined speed in the direction of the arrow. In this developing sleeve 1, an insulating layer 1 made of an insulating material such as chloroprene is placed on the circumferential surface of a sleeve-shaped conductive base 1a made of aluminum or the like.
b is deposited, and a surface electrode layer 1C is further deposited thereon. This surface electrode layer 1
C is formed by dispersing a large number of microelectrode particles in an electrically insulating state from each other in an insulating adhesive layer. This developing sleeve 1 is connected to a power source 1d, and a developing bias voltage 8 is applied thereto. This developing bias voltage VB is set to -180V.

The insulating layer 1b is provided to maintain an electric field strength suitable for development, and can be omitted if necessary.

In this example, a hopper 2 for storing developer is formed on the right side of the developing sleeve 1 in the figure. The developer used in this example is a non-magnetic one-component toner. A replenishment port 2a is formed in the upper part of the hopper 2, into which a cartridge 3 filled with toner is attached, and new toner is replenished into the hopper 2 by falling naturally. There is. Inside the hopper 2,
An agitator 4 is rotatably arranged to send out the toner toward the developing sleeve 1 while preventing the toner from agglomerating.

On the exit side of the hopper 2 that supplies toner to the developing sleeve 1 side, a toner supply roller 6 serving as a developer supplying member that promotes the movement of toner to the surface of the developing sleeve 1 is rotatably disposed. .

This toner supply roller 6 is preferably supported at a position where its surface can be brought into pressure contact with the surface of the developing sleeve 1, and is desirably driven to rotate in the same direction as the developing sleeve 1. That is, at the contact portion between the two, it is preferable that both surfaces are moved in opposite directions while being in pressure contact with each other. As a result, the toner is sandwiched between both surfaces and efficiently charged by friction, and the layer pressure is regulated so that an appropriate toner layer is formed on the surface of the developing sleeve 1. In this case, even if the toner supply row 56 is disposed in a non-contact state with respect to the developing sleeve 71, the toner is transferred to the developing sleeve 71.
It is possible to obtain the same effect as in the case of contact by using a toner with high charging efficiency or by using means such as providing a separate pressing member to adhere and form a toner layer. Can be done. Further, although the preferable circumferential speed of the surface of the toner supply roller 6 varies depending on the circumferential speed of the developing sleeve 1, overall, it is set to a higher speed than the developing sleeve 1, and the surface of the developing sleeve 1 and the toner supply roller 6 are preferably set at a higher speed than the developing sleeve 1. It is preferable that the surface is rotated while being in sliding contact with the surface. However, if the speed is set too high, there will be side effects such as toner scattering, toner sticking at the bearing, and promotion of toner aggregation within the hopper 2, so it is required to set the speed within an appropriate range. It is desirable that the material of the surface portion of the toner supply roller 6 has a frictional charging line distant from the toner in order to efficiently frictionally charge the toner.

In this example, the degree of foaming on the peripheral surface is preferably 10 to 10 in terms of the number of cells.
A sponge roller 6 having a surface layer of 100 pieces of flexible material such as polyurethane foam is disposed so as to be able to rotate in the same direction as the developing sleeve 1 while being in pressure contact with the surface of the developing sleeve 1. . This sponge roller 6
is impregnated with a conductive material such as carbon black, and is formed so that its electrical resistance is 10 6 Ωα or less. 1. This toner supply roller 6 is electrically grounded, and the toner supply roller 6 is electrically grounded.
Bias voltages V and U for toner supply applied to are OV
is set to .

In this case, the developing sleeve 1 with a diameter of 25.4M is 400mm in diameter.
It is rotated at a speed of rpm, while the diameter is 1
The toner supply roller 6 of 411IIR is rotated at 800 rpm, and the speed ratio thereof is set to about 10:11. Note that in order to convey an appropriate amount of toner to the contact portion and form a suitable toner layer on the surface of the developing sleeve 1, the hardness of the flexible material should be high, and the pore diameter should be small.

By providing the toner supply roller 6 as described above,
The toner -0- sent into the hopper 2 is moved following the rotation of the toner supply roller 6 as will be described later, and is smoothly transferred to the contact portion. At the contact portion, the toner transferred between the surfaces of the developing sleeve 1 and the toner supply roller 6 that are moved in opposite directions is pinched, and at this time, it is frictionally charged and the toner is transferred to the surface of the developing sleeve 1. Can be attached to surfaces. In this case, the force that causes the toner to follow the rotation of the toner supply roller 56 is mainly caused by electrostatic force caused by friction between the toner and the toner supply roller 6. Therefore, even if the developer is a non-magnetic one-component toner containing neither carrier nor magnetic material, it can be smoothly transferred and supplied from the hopper 2 to the surface of the developing sleeve 1. Note that the developer supplying member is not limited to a flexible roller, but may also be a fur brush, a metal or plastic roller, or the like.

Along the rotational direction of the developing sleeve 1, on the downstream side of the toner supply roller 6, there is a developing device that controls and thins the layer thickness of the toner layer that is formed on the surface of the developing sleeve 1 and is conveyed as the developing sleeve rotates. A doctor blade 7 is provided as a agent regulating member. This doctor blade 7 may be made of either an elastic material or a hard material, but in this example, it may be made of, for example, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer on one side of the main body made of an elastic member. It is formed by adhering an insulating film made of a fluororesin such as PFA, and its tip is pressed against the surface of the developing sleeve 1 through the insulating film so that the layer thickness of the toner is regulated. It has become. In this case, the supporting direction of the doctor blade 7 may be either a trailing direction in which it is supported along the rotational direction of the developing sleeve 1 or, conversely, a counter direction opposite to the rotational direction as in this example. It is important to bring the leading edge portion into contact with the surface of the developing sleeve 1. As a result, the toner layer thickness can be reliably and uniformly regulated over substantially the entire required area in the width direction of the developing sleeve 1, and it is possible to stably form a thin toner layer with a uniform layer thickness. . In addition, the above-mentioned insulating film is provided to prevent toner from sticking and improve charging characteristics, and by using a fluorine-based material as in this example,
- The layer effectively prevents toner from sticking and triboelectrically charges the layer.

In addition to the above-mentioned PFA, the developer regulating member may include polytetrafluoroethylene (TFE), tetrafluoroethylene-hexafluoropropylene copolymer (
FEP), tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (
Preferable materials include fluorine-containing polymer materials such as CTFE (CTFE) and materials containing fluorine-containing polymer materials, as well as materials with high releasability for toner, such as polyethylene, polypropylene, and silicone resins. In addition, 1. In order to improve the wear resistance of these materials, additives such as carbon black, carbon fiber, glass IJAN, silica fine powder, SiC fine powder, etc. may be included.

A portion of an endless organic photoreceptor belt (OPC belt) 8 as a latent image carrier rotatably stretched and the above-mentioned are placed at a suitable position on the downstream side of the doctor blade 7 in the rotational movement path of the developing sleeve 1. The surface of the developing sleeve 1 is brought into contact with the surface of the developing sleeve 1 to form a developing area. The electrostatic latent image formed on the surface of the OPC belt 8, which is uniformly charged at a proper location and subjected to an image exposure process, is conveyed to the development area as it rotates. A thin layer of toner whose layer thickness is regulated by a doctor blade 7 and which has been sufficiently triboelectrically charged is carried on the surface of the developing sleeve 1 and conveyed to the developing area.

A toner scraping roller 9 as a developer scraping member that removes developer remaining on the surface of the developing sleeve 1 after development is provided on the downstream side of the developing area along the rotational direction of the developing sleeve 1. . The toner scraping roller 9 is formed of a sponge roller having a surface layer made of a flexible material such as polyurethane foam having a suitable degree of foaming of 10 to 100 cells on its circumferential surface. It is disposed so that it can be rotated in the same direction as the developing sleeve 1 while being in pressure contact with the surface of the developing sleeve 1 .

Furthermore, this toner scraping roller 9 is impregnated with a conductive material such as carbon black, and its electrical resistance is 10.
It is formed to have a resistance of 6Ωα or less. A power source 9a is connected to this toner scraping roller 9.
A bias voltage having a polarity opposite to the charging polarity of the toner is applied to the toner scraping roller 9 to inject charges for toner adsorption onto the developing sleeve 1 side. The bias voltages V and C for charge injection are controlled to fluctuate as described later, but are basically set to -300V.

Further, the power supply 9a is provided with a voltage control device 9b that adjusts the applied voltage. This voltage control device 9b controls the output voltage of the voltage generator 19a based on the signal from the copy counter 90, and is configured so that a predetermined bias voltage is simultaneously output when a predetermined number of copies is reached. It has the function to control. Note that when new toner is replenished from the hopper 2 side, the copy number total 9C is reset and a new counting operation is started.

In the developing device in such an embodiment, the toner remaining on the developing sleeve 1 after the completion of development is
As the developing sleeve 1 rotates, the toner is transported to a position where the toner scraping roller 9 is provided, where it is easily scraped off from the surface of the developing sleeve 1. That is, the sponge roller 9 is brought into pressure contact with the developing sleeve 1 and is bent to be in a face-to-face state over a predetermined length, and the mechanical sliding force between the rollers due to the rotation of the toner scraping roller 9 at the contact portion and the bias voltage ■ is removed from the developing sleeve 1 based on the electric adsorption force (electrostatic attraction) C. This will prevent image retention in the next copy cycle.

At the same time as this toner scraping action, the developing sleeve 1
On the other hand, a charge for toner adsorption is injected from the toner scraping roller 9, and the surface portion of the developing sleeve 1 is at approximately the same level as the bias voltage applied to the toner scraping roller 9, that is, on the toner adsorption side. placed in a potential state. As a result, electrostatic attraction due to the residual charge on the developing sleeve 1 is applied, and the toner supply performance is improved as described below.

With respect to the developing sleeve 1 which is brought into the toner-adsorbing potential state as described above, toner is well supplied from the toner supply roller 6 side to the developing sleeve 1 side due to the electrostatic attraction exerted based on the toner-adsorbing potential. Then, toner is attached to the surface of the developing sleeve 1. That is, the toner supply roller 6 is in pressure contact with the developing sleeve 1 and bent, and is in a face-to-face state over a predetermined length, and as described above, the toner supply roller 6 carries and conveys the toner, especially on the upstream side of the contact portion. It exhibits the effect of making the toner adhere to the surface of the developing sleeve 1 while regulating the toner that flows therethrough.

At this time, the bias voltage v8o applied to the toner scraping roller 9 is controlled to fluctuate in response to the temporal change in the toner particle diameter, that is, the temporal change in the toner adsorption potential, and the amount of charge injected into the developing sleeve 1 side is controlled. By changing it, the electrostatic attraction by the developing sleeve 1 can be adjusted, and as a result, the amount of toner supplied can be controlled to an appropriate amount so that the image density is always constant. In this case, since the toner supply roller 6 side is grounded, the developing sleeve 1
It is possible to eliminate the charge that tends to remain on the surface. Therefore, the developing bias VB can be operated in the same manner as in the initial state without the influence of charge injection, and the developing sleeve 1
Image density fluctuations due to the synergistic effect of the residual charge and the developing bias can be completely avoided. therefore,
Image density can be controlled only by controlling the bias voltage vSC to the toner scraping roller 9.

Furthermore, if the amount of charge injected into the developing sleeve 1 side by the bias voltage Vso applied to the toner scraping roller 9 is insufficient, in order to compensate for this, the bias voltage V8u for toner supply from the toner supply roller 6 is applied. It is also possible to perform charge injection. At this time, the bias voltage vsc applied to the toner scraping roller 9 is kept almost constant, and the toner supply bias voltage v8U applied to the toner supply row 56 is controlled to vary, thereby controlling the toner supply amount. By directly changing the toner supply amount, the toner supply amount is controlled to an appropriate amount so that the image density is always constant.

The present invention can be applied to a developing device that uses either magnetic toner or non-magnetic toner. Further, the present invention can be applied to both a normal rotation developing device and a reversal developing device.

In the case of reversal development, the charge polarity of the photoreceptor, the charge polarity of the toner, and the polarity of the applied bias voltage are the same.

As for the bias applied voltage values, for example, the bias voltage VSC for toner scraping is -200V, the bias voltage V8U is for toner supply, -700V1 the developing bias voltage is -5.
A case may be considered where each is set to 00■.

(Effects) As described above, the developing device according to the present invention removes the developer remaining on the developer carrier after development and removes the developer between the developing area and the developer supply member. Since the carrier is provided with a developer scraping member that injects charge for developer adsorption, it is possible to maintain a constant image density at all times with a simple configuration, regardless of changes in toner particle diameter over time. .

[Brief explanation of the drawing]

The figure is an explanatory longitudinal cross-sectional view of a developing device in an embodiment of the present invention. 1...Developing sleeve, 6...Toner supply roller, 8
. . . Photoreceptor belt, 9 . . . Toner scraping roller. (1 person outside)

Claims (1)

[Claims] In a developing device including a developer carrying member that holds and conveys a one-component developer to a developing area, and a developer supplying member that supplies toner to the developer carrying member, the developing area and the developer supplying member are provided. A developer scraping member for removing the developer remaining on the developer carrier after development is provided between the developer carrier and the developer carrier. A developing device characterized in that a bias voltage for injecting charge for adsorption is applied.