JPH0736266A - Developing device - Google Patents

Abstract

PURPOSE:To provide a developing device capable of always securing the stable electrostatic charging quantity and coating of a developer and obtaining a high quality image having a stable density by preventing the inflow of a developer from the upper side of a side plate in a developer housing chamber. CONSTITUTION:The developing device 13 is constituted in such a manner that a developing sleeve (developer carrier) 2 and the toner housing chamber (developer housing chamber) 5 are provided, the toner (developer) 10 and a stirring device 18 are housed in the toner housing chamber 5 and the stirring device 18 is constituted so as to include a stirring blade (stirring member) 6 slid on the bottom part in the toner housing chamber 5 and a rotary center shaft 8 driving the stirring plate 6. Plate-like members 9 are provided on both end parts of the rotary center shaft 9 of the stirring device 18. The inflow of the toner 10 from the upper sides of both end parts in the toner housing chamber 5 is prevented by the plate-like members 9 provided on both end parts of the rotary center shaft 8 and the toner 10 can be stably supplied to the developing sleeve 2, simultaneously, the stable electrostatic charging quantity and coating of the toner can be always secured, to obtain the high quality image of the stable density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing a latent image formed on an image carrier by an electrophotographic system or an electrostatic recording system.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a laser beam printer, each unit such as a charging device, a photoconductor as an image carrier, a developing device, and a cleaner device has a different life. So-called toner cartridges have been developed.

Generally, as a developing device, as shown in FIG. 5, the toner 10 is formed by a developing sleeve 2 having a predetermined gap with an image carrier (hereinafter referred to as a photosensitive drum) 1.
Of the latent image formed on the photosensitive drum 1 by the toner 10 while converting the latent image formed on the photosensitive drum 1 into a visible image while applying an appropriate bias voltage between the developing sleeve 2 and the photosensitive drum 1. Things are widely used.

Various types of toner are used as the toner 10. Here, the case of using a dry one-component magnetic toner will be described.

By the way, in the toner cartridge developed in a small size, the toner accommodating chamber 5 in the developing device 13 becomes narrow, and therefore, as a stirring device 18 for the toner 10 in the toner accommodating chamber 5, a bottom portion of the toner accommodating chamber 5 is used. Is provided with a stirring plate 6 configured by combining plate-shaped or rod-shaped members, and a rotation center shaft 8 driven by a stirring gear (not shown) is centered on a center point 20 and is shown in a direction of an arrow C in the drawing with respect to a center line 19. A method of agitating and conveying the toner 10 by sliding the agitating plate 6 in the direction of the arrow A in the figure through the arm 7 by rotating the toner a few degrees at a time (hereinafter referred to as a slide agitating method) is adopted. What is done is used.

In order to accurately transmit the driving force received by the rotation center shaft 8 to the entire stirring plate 6, the arms 7 are attached to both ends of the rotation center shaft 8 as shown in FIG. .

[0007]

However, the developing device 13 employing the slide stirring method shown in FIG. 5 has the following problems.

That is, in the vicinity of the side plate in the toner storage chamber 5, the toner 10 is likely to collapse when the stirring plate 6 moves, so that as the toner 10 is consumed, development is performed from the vicinity of the upper side plate in the toner storage chamber 5. The toner 10 flows into both ends of the sleeve 2 in the longitudinal direction, and the toner 10 is packed by the arms 7 near the toner intake ports at both ends of the developing sleeve 2.

Then, the packed toner 10 comes into contact with the developing sleeve 2 at a high pressure, and the toner 10 is fused to the developing sleeve 2 and contaminates the developing sleeve 2, so that the developing The contaminated portion of the sleeve 2 loses its ability to impart charge to the toner 10,
Further, it becomes impossible to stably convey the toner 10, and there arises a problem that the density at both ends of the image becomes thin.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent the developer from flowing from above the side plate in the developer accommodating chamber to always provide a stable developer charge amount and a developer. It is an object of the present invention to provide a developing device capable of ensuring a coating and thereby obtaining a high-quality image.

[0011]

In order to achieve the above object, the present invention has a developer carrying member and a developer accommodating chamber, and accommodates the developer and the agitating device in the developer accommodating chamber. In a developing device including a stirring member that slides on the bottom of the developer accommodating chamber and a rotation center shaft that drives the stirring member, plate members are provided at both ends of the rotation center shaft of the stirring device. It is characterized by

[0012]

According to the present invention, the plate-like members attached to both ends of the central axis of rotation of the stirring device prevent the developer from flowing into the developer accommodating chamber from above both ends thereof, and the developer is carried to the developer carrying member. It is possible to stably supply the developer, always secure a stable developer charge amount and developer coating, and obtain a high-quality image with stable density.

[0013]

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

<First Embodiment> FIG. 1 is a sectional view of an essential part of an image forming apparatus equipped with a developing device according to the present invention.

In the image forming apparatus according to this embodiment,
The photosensitive drum 1 as an image carrier is uniformly charged at a predetermined potential by the charging device 11 during the rotation process, and then is exposed to an image by an image exposure device (not shown) at the exposure unit 12, and the photosensitive drum 1 is electrostatically charged on the photosensitive drum 1. A latent image is formed.

The electrostatic latent image formed on the photosensitive drum 1 is then developed by the developing device 13 to be visualized as a toner image, and the toner image is transferred onto the transfer material P by the action of the transfer roller 14. To be done. Then, the transfer material P to which the toner image has been transferred is separated from the photosensitive drum 1 and introduced into the fixing device 15, where after the toner image is fixed by the fixing device 15, it is transferred outside the apparatus as a copy. Is discharged.

After the transfer of the toner image, the cleaning drum 16 removes the untransferred toner from the photosensitive drum 1,
It is subjected to the next image forming process.

By the way, the developing device 13 uses the toner 1
It has a developing sleeve 2 which is a developer carrying member for carrying 0 and carrying it to the photosensitive drum 1 and a toner accommodating chamber 5.

The developing sleeve 2 is made of a non-magnetic material such as aluminum or stainless steel, and a fixed magnet 3 is arranged inside the developing sleeve 2. In this embodiment, the surface of the developing sleeve 2 is processed with, for example, # 400 blast particles, and the surface roughness thereof is JIS10.
The point average roughness was Rz = 2.0 μm. The unevenness formed by this processing is preferably uniform, and the average roughness Rz of the surface of the developing sleeve 2 is preferably smaller than the average particle size of the toner particles.

The developing sleeve 2 is rotatably supported by a bearing (not shown). In this embodiment, the peripheral speed is 36 m.
It is rotationally driven in the direction of arrow D in the figure at m / sec. The developing sleeve 2 is connected to a power source capable of superimposing an AC bias on a DC bias, and the bias to be applied to the developing sleeve 2 is V _PP = 500 to 3000V,
It has been experimentally confirmed that f = 500 to 3000 Hz is suitable. In this embodiment, _VDC = −450V,
A bias of V _PP = 1200 V and f = 1800 Hz was applied to the developing sleeve 2.

Further, the developing sleeve 2 is supported opposite to the photosensitive drum 1 with a predetermined developing gap, and the developing gap is preferably 150 to 500 μm, and in this embodiment, it is set to 300 μm.

An elastic blade 4 as a toner regulating member is in contact with the developing sleeve 2, and the elastic blade 4 is made of urethane rubber having a hardness of 50 to 80 °, for example.
A rubber elastic body such as silicone rubber or NBR is desirable, and in this embodiment, urethane rubber having a thickness of 0.9 mm and a hardness of 67 ° is used. In addition, as the elastic blade 4, a metallic elastic body such as phosphor bronze or stainless steel, a synthetic resin elastic body such as polyethylene terephthalate, or the like may be used.

One end of the elastic blade 4 is fixed by a support 17, and the elastic blade 4 is brought into contact with the developing sleeve 2 in the direction opposite to the rotating direction by the elastic force of its own deformation. When the toner 10 is not carried on the developing sleeve 2, the elastic blade 4 directly contacts the developing sleeve 2, and when the toner 10 is carried, the elastic blade 4 applies a thin layer of the toner 10 to the developing sleeve 2. Abut against as if pressing against.

By the way, in this embodiment, a one-component magnetic toner is used as the toner 10, and the toner 10 is stored in the toner storage chamber 5.

Thus, the toner 10 in the toner storage chamber 5
Is attracted to the developing sleeve 2 by the magnetic force of the magnetic pole S ₂ of the fixed magnet 3 incorporated in the developing sleeve 2. still,
The magnetic force of the magnetic pole S ₂ of the fixed magnet 3 is 400 at the peak value.
If Gauss or above, sufficient toner 10 is applied to the developing sleeve 2.
However, in this embodiment, the magnet 3 whose magnetic force of the magnetic pole S ₂ has a peak value of 600 gauss is used.

On the other hand, the toner storage chamber 5 is provided with a developing sleeve 2 at the lower opening, and the developing sleeve 2 is arranged along the photosensitive drum 1 in the direction perpendicular to the paper surface of FIG.

A stirring device 18 is accommodated in the toner accommodating chamber 5 in addition to the toner 10, and the toner 10 is successively applied on the surface of the developing sleeve 2 near the magnetic pole S _{2 of the} magnet 3 by the stirring device 18. Is transported.

In the stirrer 18, the rotation center shaft 8 receives a driving force from a stirring gear (not shown), and the center point 20 is the center of rotation from the center line 19 in the direction of the arrow C in the drawing to an angle of 35 °.
By rotating each of them, the plate-shaped member 9 attached to the rotation center shaft 8 is also integrally rotated in the same direction by the same angle, and the rotation of the rotation center shaft 8 is agitated via the arm 7. The plate 6 is converted into a linear motion, and the stirring plate 6 is slid in the inner bottom portion of the toner storage chamber 5 in the direction of arrow A in the figure.

By the way, the plate member 9 is attached to both ends of the rotation center shaft 8 as shown in FIG.
The plate-shaped member 9 prevents the toner 10 from flowing in from the vicinity of the upper side plate in the toner storage chamber 5.

The stirring plate 6 is composed of three rod-shaped mold members 6a each having a pentagonal cross section and arranged at intervals of 9 mm in parallel with the longitudinal direction of the developing sleeve 2 (the direction perpendicular to the paper surface of FIG. 1). It is configured by combining three rod-shaped mold members 6b arranged at equal intervals in the direction perpendicular to the longitudinal direction of the developing sleeve 2 (obliquely left and right direction in FIG. 1) at intervals of 50 mm.

By the way, the developing device 13 according to the present embodiment.
Can fill 180 g of the toner 10 in the toner storage chamber 5, and FIG. 1 shows a state in which 110 g of the toner 10 remains in the toner storage chamber 5.

Thus, in this embodiment, the plate-like members 9 provided at both ends of the rotation center shaft 8 of the stirring device 18 prevent the toner 10 from flowing into the toner accommodating chamber 5 from the vicinity of the upper side plate. Therefore, packing of the toner 10 in the vicinity of both ends of the developing sleeve 2 is prevented, and the developing sleeve 2 can stably coat the toner 10 and impart charge to the toner 10. As a result, conventional As described above, the problem that the density at both ends of the image becomes low does not occur.

Incidentally, in this embodiment, the average particle size is about 7 μm.
When 160 g of the one-component magnetic toner 10 of m was put into the image, an image of 3,000 sheets was obtained, and only 15 g of the toner 10 remained on the 3,000th sheet, but the density becomes low at both ends of the image. In addition, the toner 10 was not contaminated at both ends of the developing sleeve 2.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. Note that FIG. 3 is a configuration diagram of a main part of the stirring device according to the second embodiment.

In this embodiment, the grid-like plate-like members 21 are attached to both ends of the rotation center shaft 8, and by adopting such a structure, when the degree of aggregation of the toner in the toner accommodating chamber is high. Can slightly prevent the toner from flowing into the ends of the developing sleeve, and stabilize the supply of the toner to the ends of the developing sleeve.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a sectional view of the developing device according to the third embodiment of the present invention. In this drawing, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

In this embodiment, the magnet plates 22 are attached to the plate-shaped members 9 attached to both ends of the rotation center shaft 8.

By adopting the above-mentioned structure, the toner 10 adheres to the magnet plate 22 to form a lump 23. Therefore, when the cohesion of the toner 10 is low, the toner 10 is agglomerated.
Is prevented, and the toner 10 is stably supplied to both ends of the developing sleeve 2.

[0039]

As is clear from the above description, according to the present invention, the developer carrier and the developer accommodating chamber are provided, and the developer and the agitating device are accommodated in the developer accommodating chamber. In a developing device including a stirring member that slides on the bottom of the developer accommodating chamber and a rotation center shaft that drives the stirring member, plate members are provided at both ends of the rotation center shaft of the stirring device. It is said that it is possible to prevent the inflow of the developer from above the side plate in the developer accommodating chamber, to always secure a stable developer charge amount and developer coating, and to obtain a high-quality image with stable density. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of an image forming apparatus equipped with a developing device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of a stirring device provided in the developing device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a main part of an agitating device provided in a developing device according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a main part of an image forming apparatus in which a developing device according to a third exemplary embodiment of the present invention is mounted.

FIG. 5 is a sectional view of a conventional developing device.

FIG. 6 is a configuration diagram of a main part of a stirring device provided in a conventional developing device.

[Explanation of symbols]

 2 developing sleeve (developer carrier) 5 toner storage chamber (developer storage chamber) 6 stirring plate (stirring member) 8 rotation center shaft 9 plate member 10 toner (developer) 13 developing device 18 stirring device 21 plate member 22 Magnet plate

Claims (3)

[Claims] 1. A developer carrying member and a developer accommodating chamber, wherein the developer and the agitating device are accommodated in the developer accommodating chamber, and the agitating device is a stirring member that slides on the bottom of the developer accommodating chamber. A developing device comprising a rotation center shaft for driving a stirring member, wherein plate members are provided at both ends of the rotation center shaft of the stirring device. 2. The developing device according to claim 1, wherein the plate-shaped member is formed in a lattice shape. 3. The developing device according to claim 1, wherein a magnet plate is attached to the plate member.