JPH07199615A - Developing device for image forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of irregularities in an image at the time of forming a full-black solid image by making the outer circumferential linear velocity of a supply member higher than the outer circumferential linear velocity of a developing roller functioning as a developer carrier. CONSTITUTION:When toner concentration is reduced in a developer container 3, a toner replenishing roller 9 is rotated in accordance with a replenishment signal from a sensor so as to replenish the toner housed in a toner cartridge part 4 into the developing container 3, and the newly replenished toner is mixed with the developer already housed in the developing container 3 and is stirred by a stirring paddle 8, to be eletrostatically charged, and also, mixed with the developer already housed in the developing container 3, dispersed, and then, transmitted to the developing roller 5 by a stirring roller 7. Provided that V1mm/s, V2mm/s and V3mm/s denote each outer circumferential linear velocity of the developing roller 5, the stirring roller 7 and the stirring paddle 8, each velocity is set so as to establish the following relation: V1<V2 and V2<V3 between them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image having an image bearing member, a developer bearing member disposed in proximity to the image bearing member, and a supply member for supplying the developer to the developer bearing member. The present invention relates to a developing device of a forming apparatus.

Further, according to the present invention, an image having an image bearing member, a developer bearing member disposed in the vicinity of the image bearing member, and a plurality of supply members for supplying the developer to the developer bearing member are provided. The present invention relates to a developing device of a forming apparatus.

Further, according to the present invention, an image bearing member, a developer bearing member disposed in the vicinity of the image bearing member, and an inclination with respect to a rotation axis for supplying the developer to the developer bearing member. And a plurality of supply members including a supply member having the agitating fins described above.

[0004]

2. Description of the Related Art In a developing device used in an image forming apparatus such as a copying machine, a printer or a facsimile, a one-component developer or a developer consisting of two components of toner and carrier is used.

When an all black solid image is formed by this developing device, as shown in FIG. 4, image unevenness may occur in which the image is slightly lightened. The image unevenness periodically occurs in the traveling direction A of the all black solid image.

[0006]

The image unevenness described above occurs in synchronism with the rotation of the stirring paddle that feeds the developer to the developing roller, and the cause thereof is poor pumping of the stirring roller that feeds the developer to the developing roller. , Or due to a change in the feed amount from the stirring paddle to the stirring roller side.

An object of the present invention is to provide a developing device which prevents the occurrence of image unevenness during the formation of the above-mentioned all black solid image.

[0008]

According to the present invention, the above-mentioned problem is solved by making the outer peripheral linear velocity of the supply member larger than the outer peripheral linear velocity of the developing roller which is the developer carrying member.

Further, according to the present invention, when a plurality of supply members for supplying the developer to the developing roller are provided, the peripheral linear velocity of the supply member located upstream in the developer supply direction is located downstream. The above-mentioned problem is solved by setting it so as to be higher than the outer peripheral linear velocity of the supply member.

Further, according to the present invention, when a plurality of supply members including a supply member having a stirring fin inclined with respect to the rotation axis are provided, the peripheral linear velocity of the supply member having the inclined stirring fin is The above-mentioned problem is solved by setting it so as to be higher than the outer peripheral linear velocity of the supply member.

[0011]

Since the outer peripheral linear velocity of the supply member for supplying the developer to the developing roller is set to be higher than the outer peripheral linear velocity of the developing roller which is the developer carrying member, there is no pumping failure of the supply member, and the supply roller is sufficiently supplied to the developing roller. By supplying such a developer, it is possible to prevent the occurrence of image unevenness when forming an all black solid image.

When a plurality of supply members for supplying the developer to the developing roller are provided, the outer peripheral linear velocity of the supply member located upstream in the developer supply direction is the outer periphery of the supply member located downstream. By setting the speed higher than the linear velocity, it is possible to ensure the sufficient supply of the developer to the developing roller.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a developing device of a copying machine using a two-component developer will be described below with reference to the drawings.

In FIG. 1, a developing device 2 as one of process units is arranged around a photosensitive drum 1 as an image carrier. The developing device 2 includes a developing container 3 that accommodates a two-component developer, and a toner cartridge 4 that supplies toner to the developing container 3. In the developing container 3, a developing roller 5 as a developer carrying member which is arranged close to the photosensitive drum 1 and rotates in the forward direction with the photosensitive drum 1, a doctor 6 for regulating the developer on the developing roller 5, and a developing roller 5, a stirring roller 7 as a supply member for supplying the developer, an agitation paddle 8 which will be described later as a supply member, a replenishing roller 9, a separator 10 arranged to face the developing roller 5 and the like are provided.

When the toner density in the developing container 3 becomes low,
The toner replenishing roller 9 rotates according to a replenishing signal from a sensor (not shown), and the toner in the toner cartridge portion 4 enters the developing container 3 and mixes with the developer already in the developing container 3. The newly replenished toner is stirred and charged by the stirring paddle 8, and is mixed and dispersed with the developer already in the developing container, and then the stirring roller 7 is used.
Is sent to the developing roller 5.

As shown in FIG. 2, the stirring paddle 8 includes a shaft 1
1 and a plurality of elliptical plates 1 attached thereto with a certain inclination angle
It is composed of 2 and. The stirring paddle 8 mainly performs a horizontal stirring action for charging, mixing and dispersing the above-mentioned replenished toner.

In FIG. 1, the peripheral linear velocities of the developing roller 5, the stirring roller 7 and the stirring paddle 8 are V ₁ mm / s and V ₂ mm / s, respectively.
And V ₃ mm / s, the following relational expression is established between these peripheral linear velocities according to the present invention.

V ₁ <V ₂ Furthermore, V ₂ <V _{3 The} above relational expression is established by appropriately selecting the tooth ratio of the gear train driving the developing roller 5, the stirring roller 7 and the stirring paddle 8. You can

Next, an embodiment in which the present invention is applied to a developing device using a one-component developer of a laser printer will be described with reference to FIG. However, the same members as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 3, the toner in the developing device 20 is supplied to the replenishing roller 22 by the rotation of the agitator 21. The replenishing roller 22 rotates while rubbing against the developing roller 5, and frictionally charges the toner to attach it to the surface of the developing roller 5. The toner adhering to the developing roller 5 is scraped off by the blade 23, so that the developing roller 5
A thin layer of toner is formed on the surface of, and thereby the electrostatic latent image on the photosensitive drum 1 is visualized.

Assuming that the peripheral linear velocities of the agitator 21 and the replenishing roller 22 of FIG. 3 are V ₄ mm / s and V ₅ mm / s, respectively, according to the present invention, the following relations exist between the peripheral peripheral velocities. The formula holds.

V ₅ <V _{4 In} this case as well, the above relational expression is established by appropriately selecting the gear ratio of the gear train that drives the agitator 21 and the supply roller 22.

[0023]

Since the outer peripheral linear velocity of the stirring roller as the developer supplying member is set to be higher than the outer peripheral linear velocity of the developing roller as the developer carrying member, the problem caused by the defective pumping of the developer is solved. Therefore, it is possible to achieve the effects of widening the tolerance width of the developer scooping pole of the developing roller, improving the margin with respect to the inclination of the developing unit, and uniformity of the black solid image (claim 1).

When a plurality of supply members are provided, the peripheral linear velocity of the upstream supply member in the developer supply direction is made higher than the peripheral linear velocity of the downstream supply member, so that the developer is supplied to the developing roller. There is no shortage, and a problem such as uneven image density due to defective drawing of the developer from the developing roller is solved (claim 2).

When a plurality of supply members are provided, a supply member provided with stirring fins having an appropriate inclination angle with respect to the rotating shaft is arranged as the first supply member. Since the outer peripheral linear velocity of the other supply member is made higher, the effect of the axial stirring function of the first supply member on the developer circulation flow is eliminated, and the supply of the developer to the developing roller is not insufficient and the development is performed. Problems such as uneven image density due to defective pumping of the developer on the roller are solved (claim 3).

[Brief description of drawings]

FIG. 1 is a sectional view of a developing device of a copying machine using a two-component developer to which the present invention is applied.

FIG. 2 is a perspective view of a stirring paddle having a plurality of inclined discs.

FIG. 3 is a sectional view of a developing device of a laser printer using a one-component developer to which the present invention is applied.

FIG. 4 is an explanatory diagram of image unevenness when forming an all black solid image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum (image bearing member) 2, 20 Developing device 5 Developing roller (Developer bearing member) 7 Stirring roller (supply member) 8 Stirring paddle (first supply member) 12 Elliptical plate 21 Agitator 22 Replenishing roller

Claims (3)

[Claims] 1. A developing device of an image forming apparatus, comprising: an image bearing member; a developer bearing member disposed in proximity to the image bearing member; and a supply member for supplying a developer to the developer bearing member. A developing device, wherein an outer peripheral linear velocity of the supply member is set to be higher than an outer peripheral linear velocity of the developer carrying member. 2. A developing device for an image forming apparatus, comprising: an image carrier; a developer carrier disposed in proximity to the image carrier; and a plurality of supply members for supplying a developer to the developer carrier. In the apparatus, the outer peripheral linear velocity of a supply member located upstream in the developer supply direction is higher than the outer peripheral linear velocity of a supply member located downstream. 3. An image bearing member, a developer bearing member disposed in the vicinity of the image bearing member, and a stirring fin inclined with respect to a rotation axis for supplying the developer to the developer bearing member. In a developing device of an image forming apparatus including a plurality of supply members including a supply member having the outer peripheral linear velocity of the supply member having the inclined stirring fins is higher than the outer peripheral linear velocity of other supply members. Developing device.