JPH049977A - Developing device - Google Patents

Abstract

PURPOSE:To develop a toner image having stable density with uniform developer by providing a developer guiding plate which is inclined from a layer thickness regulating member side to a carrying and stirring screw and provided with a member for guiding the developer to a front side on its upper surface. CONSTITUTION:The developer in which toner is uniformly distributed by screws 7A and 7B is carried to the circumferential surface of a developing sleeve 3 by a stirring plate 6 and passes below the layer thickness regulating member 5 to be fed to a developing area. The excess toner jumps back from the circumferential surface of the sleeve 3 and scatters and drops on the upper part of the developer guiding plate 8, then it slides down along the inclined surface of the plate 8 but it circulates to the front side of a developing device 2, that means, an upper-stream side in a carrying direction by the screw 7B by means of a guiding member 8A of the upper surface of the plate 8. Then, it is mixed and stirred with the developer to which the toner is replenished again and becomes the developer which is uniform and rich in fluidity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device, particularly to a developing device used in an electrostatic recording device such as an electrophotographic copying machine.

[Background of the invention]

This type of developing device is mainly equipped with a hole containing toner for replenishment on the external side of the device, and as a result of detecting the toner concentration in the developer or the image density, it is determined that the density is low. Toner is automatically replenished according to the replenishment signal.

The replenished toner is mixed into the developer while being conveyed in the development width direction by a spiral screw built into the developing device, and is made into a two-component developer with a sufficient and uniform toner concentration.

In order to enhance the stirring effect, the above-mentioned screw has a screw that has a propulsion force in the opposite direction arranged in parallel below, and the developer transported by the upper screw is passed through small diameter holes dotted in the partition plate and sent to the lower screw. It is dispersed and stirred by its reciprocating action.

Regarding this type of developing device, the present applicant has already published Japanese Patent Application Laid-Open No. 163968/1982 and Japanese Patent Application No. 1578/1999.
The proposal in the specification of Publication No. 54 has contributed to the improvement of the performance, but since the above-mentioned partition plate is formed into a gutter-like shape close to the screw surface in order to increase the conveyance efficiency, it is difficult to develop with the small-diameter holes mentioned above. The problem remains that this results in applying a harmful external force to the developer, thereby causing great damage to the developer.

Therefore, the present applicant further proposed a developing device in which the above-mentioned screws are arranged in parallel in a horizontal state in Japanese Patent Application Laid-open No. 62-7073, thereby eliminating the need for the above-mentioned partition plate and small-diameter holes, and preventing damage caused by external force. This makes it possible to obtain a high-quality developer that is free from damage.

(Flame - θ) However, in the developing device in which the screws are arranged in parallel in this way, the developer that hits the developing sleeve and bounces back or is blocked by the layer thickness regulating member,
Since there is a strong tendency for the reflux to concentrate mainly on the screw near the developing sleeve, there still remains a difficulty in achieving homogenization of the entire developer.

As a result of solving and improving this point, the present invention aims to solve the above-mentioned problem and thereby provide a developing device that can always develop a toner image with a stable density using a homogeneous developer. .

[Structure of the invention]

The above purpose is to provide a developing sleeve that conveys the developer regulated by a layer thickness regulating member from above to the developing area, a stirring means behind the developing sleeve, and inner and outer conveying/stirring screws behind the developing sleeve. Arranged almost horizontally, a toner replenishment port is provided on the front side of the outer conveyance/stirring screw, and the outer conveyance/stirring screw conveys and stirs the developer toward the rear side, and the inner conveyance/stirring screw toward the front side. In the developing device, a developer guide plate is provided above the stirring means and the conveyance/stirring screw, and is provided above the stirring means and the conveyance/stirring screw, and is inclined downward from the front side close to the layer thickness regulating member toward the outer conveyance/stirring screw. This is achieved by a developing device characterized in that a developer guide member is attached to the upper surface of the device to incline and convey the developer toward the front side.

〔Example〕

One embodiment of the invention is shown in FIGS. 1 and 2.

Fig. 1 shows a cross section of the main part of the image forming section in the image forming apparatus, and Fig. 2 shows a plane view with the top open.
2 is a photoreceptor drum, and 2 is a developing device disposed around the periphery of the photoreceptor drum l.

In the developing device 2, 3 is a developing sleeve, 4 is a fixed magnet roll, and 5 is a developer layer thickness regulating member installed at the peripheral edge of the developing sleeve 3.

On the other hand, reference numeral 6 denotes a stirring plate composed of a plurality of radial blades, which is the main stirring means for the developer, and 7A and 7B denote respective conveyors arranged at horizontal positions inside and outside the developing device 2, respectively, behind the stirring plate 6.・Stirring screw (hereinafter simply referred to as screw)
It is.

Reference numeral 8 denotes a developer guide plate that vertically divides the space above the stirring plate 6 and the screw 7A. It is located close to the developing sleeve 3 and the layer thickness regulating member, and its right end slightly reaches the top of the screw 7B.

The guide plate 8 is fixed to the inner surface of the lower casing 2B of the developing device 2, and guides the developer scattered or fallen on the upper surface of the guide plate 8 to the screw 7B by sliding it down along the inclined surface.

Furthermore, a plurality of inclined guide members 8A as shown in FIG. 2 are provided on the above-mentioned inclined surface.

This guide member 8A is integrated with the guide plate 8 by integral molding or by adhering separate members.

The guide member 8A is linearly inclined toward the front toward the right end of the guide plate 8, and serves to guide the developer on the upper surface of the guide plate 8 to the upstream side of the conveyance of the screw 7B.

1O is a hopper that stores toner to be supplied to the developing device 2, and the hopper 10 is connected to a protruding portion 2C of the lower casing 2B that accommodates the extension of the screw 7B; It is attached removably.

The developing device 2 is placed on a pedestal 11 in the image forming apparatus, is pressed toward the photosensitive drum 1 side by a biasing device 2 provided on the pedestal 11, moves in parallel on the pedestal 11, and is moved by an abutting member ( (not shown), the distance between the developing sleeve 3 and the surface of the photosensitive drum 1 is maintained at a specified value, and a required developing gap is set.

The conveyance and agitation of developer and the replenishment of toner in the developing device 2 are performed as follows.

The screws 7A and 7B are both formed with rightward spiral surfaces, and the screws 7A and 7B are rotated clockwise and counterclockwise by the meshing of coaxial gears Gl and G2, respectively. screw 7
A has a propulsive force in the front direction, and the other screw 7B has a propulsive force in the depth direction.

The toner for replenishment that has fallen from the hopper 10 to the toner replenishment port is transported along with the existing developer in the developing device 2 in the depth direction of the device by the propulsive force of the screw 7B, and in the process, it passes through the partition wall 2D at the bottom of the lower casing 2B. Climb over and move to the screw 7A side.

The upper edge of the partition wall 2D is sloped low in the depth direction, so that even if the amount of developer decreases during transportation, the developer can be transferred at a substantially uniform rate.

The developer including the replenishment toner that has migrated to the screw 7A side is transported back toward the front by the propulsive force of the screw 7A, and is mixed and stirred by the reciprocating transport operation so that the developer or replenishment toner is evenly distributed. Ru.

The developer with toner evenly distributed by the screws 7A and 7B is further stirred by the counterclockwise rotation of the stirring plate 6 and is conveyed to the circumferential surface of the developing sleeve 3. That is, by being stirred as described above, the toner in the developer is charged to a potential opposite to that of the electrostatic latent image formed on the photoreceptor drum 1.

The developer conveyed to the developing sleeve 3 by the stirring plate 6 is partially conveyed to the developing area by passing under the layer thickness regulating member 5 by counterclockwise rotation of the developing sleeve 3, and the rest is conveyed to the developing area. The developer bounces off the circumferential surface of the sleeve 3, scatters and falls onto the upper part of the guide plate 8, slides down along the slope, flows back to the screw 7B, and is mixed and stirred again with the developer that has been supplied with toner. It is considered to be a homogeneous and highly fluid developer.

When the developer that has scattered and fallen onto the guide plate 8 slides down on the slope, the direction of the developer is directed by the guide member 8A to the developing device (
! ! It is restricted to the front side of 2.

As a result, the developer falling from the guide plate 8 is circulated more upstream in the direction of conveyance by the screw 7B, and the effects of the above-mentioned mixing and stirring are further enhanced.

〔Effect of the invention〕

According to the present invention, the toner supplied from the hopper is mixed and stirred so as to be evenly distributed, and a developer with a stable toner concentration is obtained.The developer is efficiently circulated and conveyed to the developing sleeve. As a result, a developing device capable of developing high-quality images by using a developer that is always homogeneous and has excellent fluidity C has been provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the developing device of the present invention, and FIG. 2 is a plan view of the main parts thereof. ■...Photosensitive drum 2A...Upper case song 2C...Protruding portion 3...Developing slot 6...Stirring plate 7 A, 7 B...Transporting/stirring screw 8...Guide plate 8A... Guide member 10...hopper
11... Frame 2... Developing device 2B... Lower case song 2D... Partition wall 5... Layer thickness regulating member block

Claims (1)

[Claims] A developing sleeve that conveys the developer regulated by the layer thickness regulating member from above to the developing area, a stirring means behind the developing sleeve, and inner and outer conveying/stirring screws are arranged substantially horizontally behind the developing sleeve. , in a developing device in which a toner supply port is provided on the front side of the outer conveyance/stirring screw, the outer conveyance/stirring screw conveys and stirs the developer toward the rear side, and the inner conveyance/stirring screw conveys and stirs the developer toward the front side; A developer guide plate inclined downward from the front side close to the layer thickness regulating member toward the outer conveyance/stirring screw is provided above the stirring means and the conveyance/stirring screw, and the upper surface of the guide plate is A developing device characterized by having a developer guiding member that is tilted and conveyed toward the front side.