JPH02132476A - Developing device - Google Patents

Abstract

PURPOSE:To execute the development whose density is stable without necessitating a complicated control by catching a drop of an interface which follows up consumption and replenishing automatically a toner in the device using a 2-component developer in which the toner and the developer make the interface in the end part of the device. CONSTITUTION:When the development of a latent image of an image carrying body 20 is started, height of a developer D in a casing 10A drops gradually due to consumption of a toner of the developer carried by a developing sleeve 11 and in a toner replenishing part 15, an interface S of a replenished toner T and the developer D drops and a space is generated in the upper part of the toner T. As a result, when the toner T in a toner bottle 16 drops down automatically and the space is filled therewith, its drop stops automatically and the replenishment is ended. In such a way, by the extremely simple device, the consumed toner is replenished exactly and automatically, and also, stirring members 13, 14 stir it equally enough and supply it to the sleeve 11, therefore, an image of stable density can be developed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a developing device for an image forming apparatus, and in particular, it performs development using a two-component developer of magnetic carrier and toner. The present invention relates to a developing device that supplies toner and performs development.

[Background of the invention]

A developing device that performs development using a two-component developer generally consists of a developing sleeve, an agitating section, and a portion of toner. It is transported to a development area facing the image carrier, and develops the electrostatic latent image on the image carrier. After the toner is consumed by development, the developer adheres to the surface of the developing sleeve, is transported, and circulates to the stirring section.

The conditions for good development with a two-component developer are that the content ratio of toner in the developer (toner concentration) must be maintained within a certain range, and the magnetization of the developer in the stirring section must be detected. The toner density is indirectly detected by developing a standard latent image formed on a photoreceptor and measuring its reflection density.

The method of detecting toner concentration by measuring the density of a developed standard latent image is indirect and does not necessarily indicate the toner ratio in the developer.

Furthermore, toner concentration measurement by detecting the magnetization of the developer has a problem in that the detection results are unstable.

Further, in the developing device, consumed toner is replenished from a portion of the toner based on the measurement results of toner density, but this inevitably complicates the toner supply mechanism and its control.

[Problem that the invention seeks to solve]

Development methods using two-component developers are roughly classified into the following three types.

(a) Two-part magnetic brush development method This is a conventional and common development method in which brush-shaped developer spikes are formed using magnetic force at a location facing the photoreceptor on the surface of the developing sleeve. This is a developing method in which the photoreceptor is brought into sliding contact with the photoreceptor bearing the latent image.

(b) Two-component non-contact development method JP-A-59-181362, JP-A-60-176
This is a developing method disclosed in Japanese Patent No. 069, etc., in which a thin layer of developer is formed on the circumferential surface of a developing sleeve, and the developing method is performed without contacting the photoreceptor.

(c) One-component non-contact developing method using a two-component developer For example, in the developing method described in Japanese Patent Application Laid-Open No. 60-42768, only toner is placed on the developing area facing the photoreceptor having a latent image on the developing sleeve. This is a developing method in which the film is attached to and transported to the surface of the film and developed.

Regarding the toner concentration in the developer in the stirring section, among the above, (b) and (C) have a particularly large tolerance compared to (a), and even if the concentration is not maintained in a very strict range, it can still be maintained in a good condition. It is clear that development will take place. Also (a
), the allowable toner concentration range can be expanded by making the carrier particles microscopic.

The present invention is a developing device in which the toner concentration in the stirring section is controlled without using toner concentration detection means and toner replenishment means based on the toner concentration detection means that have been studied in various ways in the past. It is an object of the present invention to provide a developing device that is suitable for the developing methods b) and (c), does not require complicated control, and has a simple structure for toner replenishment.

13-41 [Means for Solving the Problems] The above object is to solve the problem in a developing device using a two-component developer in which the replenished toner and the retained developer form an interface at the end of the device. This is achieved by a developing device characterized in that replenishment of toner is automatically started when the interface falls due to consumption.

〔Example〕

An embodiment of the present invention is shown in FIG.

The figure shows a developing device 1'lO of the present invention and its casing lOA in a partially cut-away state.

In the figure, 11 is a developing sleeve, 12 is a scraping rod for scraping off the magnetic carrier remaining on the circumferential surface of the developing sleeve 1l, 13 and 14 are both a set of stirring members having rightward spiral surfaces, 13A and 14B. are each of the above-mentioned stirring members 1
The gears 13A and 14A have the same number of teeth and are configured to mesh with each other. It is connected to the rotation shaft of the sleeve 11.

15 is a toner replenishing part 16 formed by expanding the casing IOA upward at one side end of the developing device 10;
1 is a toner bottle filled with toner T for replenishment, and the toner bottle 16 is bayonetly connected to a mount on the upper surface of the toner replenishing section 15 in an inverted position, thereby being attached and fixed, and opened at the same time.

When the developing device 10 is attached to the main body of the image forming apparatus, the developing sleeve 11 is biased so as to maintain an appropriate developing distance (Dsd) from the circumferential surface of the image carrier 20 using a member such as a well-known abutment roller. Positioned via. At the same time, the power system from the main body of the apparatus is connected to the developing sleeve 1l and the scraping rod 12, so that the rotation of the stirring members 13 and 14 is also transmitted.

In the stirring section on the opposite side of the toner supply section, the stirring member 1
In order to prevent clogging of the circulating developer according to 3.14, a space is provided above the stirring section at the end.

When copying starts, the image bearing member 20 and the rotating members including the developing sleeve 11 in the developing device 10 begin to rotate and the developing action of the electrostatic latent image on the image bearing member 20 begins. Since the toner component of the developer continues to be consumed, as a result, the height of the layer of developer D in the casing 10A gradually decreases.

Therefore, inside the toner supply section l5,
As the interface S between the toner T and the developer D that has already been replenished falls, a space is created above the toner T, so the toner T in the toner bottle l6 automatically falls and is replenished into the toner replenishing section 15. .

When the space in the toner replenishing portion 15 is filled up by replenishing the toner T, the toner T from the toner pot 16 automatically stops falling, and the replenishment ends.

It is preferable to periodically vibrate the toner bottle 16 so that the toner T can be smoothly replenished.

This toner replenishment action is performed continuously during the developing operation, and the developer D containing a sufficient amount of toner T necessary to maintain a predetermined image density is always secured in the developing device 10.

The toner T supplied from the toner pot 16 falls onto the end of the stirring member 14, and is conveyed in the eight directions of the arrow by the clockwise rotation of the stirring member 14. The conveyed toner T is conveyed back in the direction of arrow B by the counterclockwise rotation of the other stirring member l3, and is evenly mixed and distributed in the developer by the mixing action therebetween.

In addition, in order to stabilize the developer interface against tilting of the developer, etc., it has a structure as shown in Fig. 2 that narrows upwardly.
Set so that the developer interface is at the lower position of the slope.

FIG. 2(a) is a side view, and FIG. 2(b) is a front view.

FIG. 2(a) has a structure in which the interface between the toner and the developer narrows upward in order to stabilize the interface.

FIG. 2(b) similarly has a structure that becomes narrower toward the top.

〔Effect of the invention〕

The present invention makes it possible to accurately and automatically replenish consumed toner in an appropriate amount using an extremely simple device, and furthermore, the replenished toner is sufficiently stirred and the toner components are evenly distributed as a developer. A developing device capable of always developing an image with a stable density by supplying the same to the developing sleeve with the same amount of water as the developing sleeve has been provided.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of a developing device according to the present invention. FIG. 2 shows a sectional view of a main part, FIG. 2(a) is a side view, and FIG. 2(b) is a front view. IO...Developing device 10A...Casing 1
1...Developing sleeve l2...Scraping stick 13.
14... Stirring member 13A, 14A... Gear l5
...Toner supply section 16...Toner bottle T...
・Toner D... (2 components) Developer S...
interface

Claims (2)

[Claims] (1) In a developing device using a two-component developer in which the supplied toner and the developer it retains form an interface at the end of the device,
A developing device characterized in that the replenishment of toner is automatically started when the interface falls as developer is consumed. (2) The developing device according to claim 1, wherein the supplied toner is conveyed and stirred into the developer by a pair of stirring members that act in opposite directions.