JPH04140774A - Developing device - Google Patents

Abstract

PURPOSE:To eliminate the need for providing a flow plate, to save a trouble for attachment and to reduce a cost by specifying relation between a roller gap and a doctor gap and setting the rotating speed of a stirring member at a speed equal to or above the rotating speed of a developing roller. CONSTITUTION:Developer stirred by the stirring member 3 is carried to a developing roller 2 and the napping height is regulated by a doctor 6, then an electrostatic latent image on a photosensitive body 5 is developed. Furthermore, the carried developer is released from the magnetic restriction of the roller 2 and stirred by the member 3. A part of the developer is carried as it is. However, since the relation of the roller gap A to the doctor gap B is set as A<=A/B<=2 mm and the rotating speed of the member 3 is higher than that of the roller 2, the developer on the roller 2 after development is all peeled off by the power of the developer which passes through the roller gap A and the developer is effectively carried toward the member 3, so that the flow plate need not be provided as in the conventional manner.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a developing device for an image forming apparatus such as a copying machine or a laser printer.

<Prior Art> Conventionally, in a normal rotation type developing device using a two-component developer in an image forming apparatus, as shown in FIG. is,
Each of them is rotated counterclockwise in the opposite direction to the photoreceptor 5. Then, a doctor 6 is placed in the developing tank l above the developing roller 2.
is provided, and a sink plate 7 is provided on the upstream side in the rotational direction of the doctor 6.
is installed.

Here, the developer after development that has been conveyed by the developing roller 2 is released from the developing roller 2, but some of the developer is conveyed by the developing roller 2 as it is.

If a large amount of developer is left after this development, the concentration of the developer supplied to the photoreceptor 1 will decrease. It is provided for the purpose of improving stirring performance by conveying the developer in the direction 3.4 and stirring it with new developer.

In the figure, 8 is a toner concentration sensor, 9 is a toner replenishment port, IO is a toner replenishment tank, 11 is a toner replenishment roller, 1
2.13 is a toner conveying member.

<Problems to be Solved by the Invention> However, providing the sink plate 7 increases the cost of the developing device, and installation of the sink plate 7 requires delicate adjustment of conditions (gap, inclination, etc.), which is time-consuming. There is such a problem.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a developing device that efficiently scrapes and collects the developer after development on the developing roller and eliminates the need for a sink plate.

Means for Solving the Problems> As shown in FIG. 1.2, the means for solving the problems according to the present invention includes a developing tank 1, a developing roller 2, and an agitating member that transports the developer to the developing roller 2 side while stirring the developer. 3 and a doctor 6 for regulating spikes of developer on the development roller 2, the roller gap A between the development roller 2 and the stirring member 3 is equal to the doctor gap between the development roller 2 and the doctor 6. With respect to B, A≦A/B≦2mm, and the stirring member 3
The rotational speed of the developing roller 2 is set to be higher than the rotational speed of the developing roller 2.

<Function> In the problem solving means described above, the developer stirred by the stirring member 3 is sent to the developing roller 2 and stands up on the developing roller 2, and while the height of the ears is regulated by the doctor 6, It is transported to the photoreceptor 5, and the electrostatic latent image on the photoreceptor 5 is developed.

Thereafter, the further transported developer is no longer magnetically restrained by the developing roller 2 and is released from the developing roller 2, and the developer released by the rotation of the stirring member 3 is stirred by the stirring member 3. Ru.

However, some of the developer is not stripped off from the developing roller 2 and is transported as it is, or the roller gap A is wider than the doctor gap B, and the stirring member 3 rotates more than the developing roller 2. Since the speed is fast, the developer on the developing roller 2 is stripped off by the force of the developer that has been conveyed by the stirring member 3 through the space between the developing roller 2 and the stirring member 3, and the developer after development is It will not be transported while remaining attached to the developing roller 2.

Therefore, all of the developer after development is stripped off from the developing roller 2 and efficiently conveyed in the direction of the stirring member 3, so there is no need to provide a sink plate as in the past, reducing costs. This eliminates the hassle of installing plates.

<Example> Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a cross-sectional view of a developing device showing an embodiment of the present invention, FIG. 2 is a detailed view of the main part, and FIG. 3 is a perspective view of a stirring member. It should be noted that the same reference numerals are given to the same components as before.

As shown in the figure, the forward rotation type developing device of this embodiment includes a developing tank 1, a developing roller 2, first and second agitating members 3 that transport the developer to the developing roller 2 while stirring it, and a developing device. The roller 2 includes a doctor 6 for controlling the spikes of the developer on the roller 2.

The roller gap A between the developing roller 2 and the first stirring member 3 is set to A≦A/B≦2−m with respect to the doctor gap B between the developing roller 2 and the doctor 6, and The rotational speed is set to be higher than the rotational speed of the developing roller 2.

Is the developer tank I located on the side facing the photoreceptor 5? Two openings 15 are formed, and the developing roller 2 is arranged on the opening 15 side,
A first agitation member 3 is disposed on a side further away from the photoreceptor 5 than the developing roller 2, and a second agitation member 4 is disposed on a side further apart from the first agitation member 3.

And develop! A toner replenishment port 9 is formed above the second stirring member 4 at 111, and a toner replenishment tank IO is detachably attached to the toner replenishment port 9.

The developing roller 2 includes a magnet body 16 that is fitted around a support shaft 2a that is rotatably supported by the developer tank l and fixed to the developer tank l, and a sleeve 17 that is rotatably fitted to the outside of the magnet body 16. The sleeve 17 is rotated counterclockwise by a motor.

As shown in FIG. 3, the first stirring member 3 and the second stirring member 4 are rotatably supported by a roller shaft 3 a in the developer tank l.
, 4a, a large number of elliptical fins 18 that are fitted and fixed to the roller shafts 3a, 4a at an angle, and vertical fins 19 that protrude in the radial direction from the roller shafts 3a, 4a between each of the elliptical fins 18. The roller shafts 3a, 4a of each stirring member 3, 4 are rotationally driven by a motor in the same direction as the developing roller 2.

Note that the rotation speed of the first stirring member 3 is set to be higher than the rotation speed of the developing roller 2. The developer is conveyed in the axial direction of the roller by the elliptical fins 18, and the vertical fins I9
It is conveyed in the circumferential direction by.

When the doctor gap B is less than 011ff1 (06 to 1.0+am), the roller gap A between the developing roller 2 and the first stirring member 3 is set to 10 to 15 mm.

In the above configuration, toner supplied from the toner supply tank 10 through the toner supply port 9 according to a command from the toner concentration sensor 8 falls onto the second stirring member 4 . Then, as the second stirring member 4 rotates, the developer and toner in the developer tank 1 are quickly mixed and stirred, the toner rubs against each other, is charged, and is sent toward the first stirring member 3 .

Thereafter, while the first stirring member 3 stirs in the axial direction, it also stirs in the circumferential direction, and the sufficiently stirred developer is sent to the developing roller 2 by the first stirring member 3, and is sent to the sleeve. The spikes stand up on the surface of the drum 17, and while the height of the spikes is regulated by the doctor 6, they are transported to the photoreceptor 5, where the electrostatic latent image on the photoreceptor 5 is developed.

Thereafter, the further transported developer is no longer magnetically restrained by the magnet body 16 in the second part of the developing roller 2, and is released from the developing roller 2, and is released by the rotation of the first stirring member 3. The developer is sent in the C direction.

However, some of the developer is not stripped off from the developing roller 2 and is transported in the D direction, but the roller gap A is wider than the doctor gap B, and the first stirring member 3 is Since the rotational speed is faster than that of the developing roller 2, the developer on the developing roller 2 is stripped off by the first stirring section, and the developed developer is not transported in the D direction.

Therefore, all of the developer after development is stripped off from the developing roller 2 and efficiently transported in the direction of the stirring member 3.4. This eliminates the need for a sink plate as in the conventional case, and reduces costs. Moreover, it is possible to eliminate the trouble of installing a sink plate.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

<Effects of the Invention> As is clear from the above description, according to the present invention, the developing tank includes a developing roller, an agitating member that transports the developer to the developing roller while stirring it, and a spike of the developer on the developing roller. and a doctor that regulates standing, and a roller gap A between the developing roller and the stirring member is a doctor gap B between the developing roller and the doctor such that A≦A, / B≦2III
I11, and the rotational speed of the stirring member is set to be higher than the rotational speed of the developing roller, so that all the developer after development is stripped off from the developing roller and efficiently transported toward the stirring member.

Therefore, unlike in the past, there is no need to provide a sink plate, which has the advantage of reducing costs and eliminating the trouble of installing the sink plate.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a developing device showing an embodiment of the present invention, FIG. 2 is a detailed view of the main parts, FIG. 3 is a perspective view of the stirring member, and FIG. 4 is a sectional view of a conventional developing device. It is. 1 developer tank, 2: developer roller, 3: first stirring member, 4,
Second stirring member, 6 Doctor, A roller gear knob, B
Ny doctor gang. Applicant Sharp Corporation Agent Tsunehisa Nakamura

Claims (1)

[Claims] In a developing device in which a developing tank is provided with a developing roller, an agitating member that agitates the developer and transports it to the developing roller side, and a doctor that regulates the spikes of the developer on the developing roller, the agitating member is provided with the developing roller and the agitating member. The roller gap A between the member and the doctor gap B between the developing roller and the doctor is
A developing device characterized in that ≦A/B≦2 mm, and the rotational speed of the stirring member is set to be higher than the rotational speed of the developing roller.