JPS5958455A - Developing device - Google Patents

Abstract

PURPOSE:To obtain a picture of good quality with good half-tone reproducibility by stirring and mixing a developer while circulating it the axial direction of a developing sleeve and supplying the developer to a developer bank, and bringing this developer into contact with an image carrier while stirring it by the rotating magnetic force of a magnet roll. CONSTITUTION:The interval d2 between a balde 4 and the developing sleeve 3 is set wider than the interval d1 between the image carrier 1 and developing sleeve 3 to alloy the developer D to pass through the gap d2 sufficiently and the blade 4 is provided closely to the image carrier 1 and developing sleeve 3. Further, a developer circulating and conveying means which circulates a two- component developer D while stirring and mixing carriers C and toner T is provided over the sleeve 3 under the influence of magnetic force from the magnet roll 2, and the developer D stirred and mixed by the conveying means is supplied to the developer bank. Consequently, the uniform and stable picture having no directivity of brush traces is obtained.

Description

[Detailed Description of the Invention] A latent image formed on an image carrier by an undeveloped BJJ1 developing device, especially an electrophotographic method, an electrostatic recording method, etc., is
The present invention relates to a developing device that produces a visible image using a two-component developer consisting of a carrier and an insulating toner (hereinafter referred to as toner).

Conventionally, the Shinki brush developing device, which has been widely used as a developing device using a two-component developer, rotates a non-magnetic sleeve containing a fixed magnet, and a magnetic carrier is coated on the surface of this non-magnetic sleeve. - A brush of two-component developer made of toner is formed, and the electrostatic latent image is developed by rubbing 4 fl with this developer brush. However, because the latent image is strongly rubbed with a brush, brush marks (brush marks) and so-called directional differences in density at the leading and trailing edges of the developed image occur, causing deterioration in image quality. .

In addition, another conventional developing device shown in FIG.
A non-magnetic developing sleeve 3 is fixedly disposed in the vicinity of the developing sleeve 3, and a magnet roller 2 with 27 magnetic poles alternately arranged in N and S poles is rotatably provided inside the developing sleeve 3. When a developer 5 consisting of a mixture of insulating toner which carries a triboelectric charge when it comes into contact with this magnetic carrier is supplied and the magnetic roller 2 is rotated in the direction of the arrow, the magnetic I roller 2 is rotated. Due to the action of the magnetic force, the developer 5 on the developing sleeve rotates on the surface of the developing sleeve in a direction opposite to the rotational force direction of the magnet roller 2, as is well known. Then, the moving developer is controlled by a developer regulating plate (hereinafter referred to as a plate) 4 whose tip is disposed close to the developing sleeve 2 at a distance d1 between the image carrier 1 and the developing sleeve 2.
The thickness of the developer layer D1 is controlled to be approximately the same as that of the developer layer D1, and the developer layer D1 is brought into contact with the image carrier I to perform development.

However, in this developing device, as shown in FIG. 2, since the developer layer D1 on the developing sleeve 3 is made up of carrier C and toner T in the form of a brush, there is a portion that does not come into contact with the image carrier 1, and the developer layer D1 on the developing sleeve 3 is in the form of a brush. Various types of development are possible, and developer contact +1
Jβ is narrow and sufficient development cannot be carried out, making it undesirable as a developing device.

The present invention has been made in view of the following two points, and has a great effect on color development because it can provide uniform image quality without brush grain directionality and provides stable image quality for halftone image development. Embodiments of the present invention will be described below with reference to the drawings, which are intended to provide a simple and compact developing device. FIG. 3 shows a schematic configuration diagram of the developing device of the present invention in which the same parts as in FIG. If the distance d between the sleeve 3 and the sleeve 3 is sufficiently widened so that the developer can pass through the distance d2, and the blade 4 is provided close to the image carrier 1 and the developing sleeve 3, the developer can be The amount of it passing through is limited by the gap between the image carrier 1 and the developing sleeve 3, and it accumulates in a delta shape in the A section. At this time, it has been confirmed through experiments that once the developer has accumulated to approximately the tip of the blade 4, the accumulation no longer grows. In addition, the portion A of this pool is caused by a change in the distance d1 between the image carrier 1 and the developing sleeve 3, a change in the rotational speed of the magnet roller 2, a change in the speed of the image carrier 1,
It was confirmed that it is stable against changes in I/toner concentration in the developer.

1- under the influence of the magnetic force of the magnet roller 2 according to the present invention
A developer circulating and conveying means is provided on the upper part of the developing sleeve 3 to circulate the two-component developer in the axial direction of the developing sleeve 3 while stirring and combining the carrier C and 1.S-T. The developer mixture stirred and mixed by the circulating conveyance means is 1
-, the developer is supplied to the developer reservoir A.

Figures 4 and 5 show an example of the developer circulation conveyance means shown in -.
A tray 20 is provided at a distance of about 1 mm) to adjust the amount of developer movement. As shown in figure t55, this tray has developer Dt inside.
- The screw 6 for conveyance is set so that it does not touch the tray (for example, about 1 to 2 + nm D', -), and is held with one foot so that it can rotate. The developer is stirred in the longitudinal direction of the developing sleeve 3 by a screw 5 arranged in parallel with the developing sleeve 3 before being conveyed. Further, the tray 20 is attached to two wooden screws 5 and 6 at a location away from one end of the Macnet roller 2, which is not affected by magnetic force.
At that point 20a, the developer is passed between the screws 5 and 6, and the screws 5 and 6
At the other end, the receiver performs the transfer in the opposite manner to the above. In other words, the function of the screws 5 and 6 is to transport the developer in the directions of arrows opposite to each other, and at one end 20a where the magnetic force does not reach,
The developer is transferred from screw 5 to screw 6, and the other end is transferred from screw 6 to screw 5 under the influence of magnetic force.

With the above configuration, carrier C and toner T are constantly stirred and mixed in the developer pool above the developing sleeve, and the stirred and mixed developer pool is supplied to developer reservoir A for development. After the development, the remaining toner T and carrier C move on the developing sleeve 3 under the magnetic force of the rotating magnet (rotating magnet) and roller 2, and the gap G between the tray 20 and the developing sleeve 3 (for example, from 2 to 3 mm to 5 to 6 mm) (It varies depending on the degree of 1.ner supply to the image and the magnetic force of the magnet roller 2.) and reaches the screw 5, and from then on j-
The developer is stirred and mixed with the developer in the second developing sleeve.

FIG. 6 shows another example of the developer circulation conveyance means, in which the screws 5 and 6 have the same length as the developing sleeve 3, and are also the same in the backward direction. The partition plate 7 is attached between the screws 5 and 6 so close that it does not touch them, and its tip is in contact with the non-rotating developing sleeve 3. The developer is supplied to the developing section A from the L side of the screw 5, and is fed along the developing sleeve 3 in the direction opposite to the rotational direction of the magnet roller 2 (the direction of the arrow in the figure), as in the example shown in FIGS. be transported. After development, the residual developer moves on the developing sleeve under the influence of the rotational strength of the magnet roller 2, and is stopped by the partition plate 7 and remains there. The screw 6 stirs and mixes the staying developer D' in the longitudinal direction of the developing sleeve 3 before transporting it. I am in charge of handing over the goods.

- Notation 6 In the example shown in Figure 6, in the case of color images and high-speed recording that consume a large amount of toner, carrier C and toner T must be quickly stirred and mixed to ensure that the developer level is uniformly sufficient. It won't happen. For this purpose, it is necessary to rotate the screw 6 at high speed to improve stirring in the longitudinal direction and at the same time to increase the supply of developer to the screw 6 by the magnetic roller 2.

Therefore, in Fig. M7, a rotating square rod 1o that approaches the developing sleeve 3 and the screw 6 and rotates in the direction of the arrow (opposite to the rotating direction of the magnet row 52) is provided, and the developer accumulated on the developing sleeve 3 is ' can be supplied to the screw 6 in large quantities. Reference numeral 9 denotes a retaining plate made of an elastic material (for example, phosphor bronze material, etc.), and a retaining part for retaining developer is connected between it and the screw 6 via a contractile member 8 (for example, foamed malt brain, etc.) attached to the tip of the retaining plate. It is something that forms.

As described above, the developing device of the present invention agitates the developer 2 in the upper part of the developing sleeve while circulating it in the axial direction of the developing sleeve! The developer in the developer pool is brought into contact with the image carrier while being agitated by the rotating magnetic force of the magnet roller, so that stable development is performed and the halftone image is created. You can obtain high-quality images with good reproduction. Furthermore, since the remaining developer after development is transferred to the upper part of the developing sleeve by the rotating magnetic force and subjected to development again, there is an advantage that there is no wasteful consumption of developer.

In addition, in FIG. 3, E is connected to the developing sleeve 31 via a resistor R.
This is a power supply that applies bias pressure. Further, as shown in FIG. 5, the screws 5 and 6 are arranged so that the developer receivers at their ends are conveyed by the end screws g5Qa and 60a of the transfer side screws so that the developer can be transferred effectively. The screw blades 50 and 60 are oriented in the opposite direction, that is, to give return force to the developer.

[Brief explanation of the drawing]

Figure 1 shows the schematic configuration of a conventional developing device, with a front view V and a
The figure is an enlarged view of the developing section, FIG. 3 is a front view of a part of the developing device of the present invention, FIG. 4 is a front view showing a developer circulation conveyance means applied to the developing device, and FIG. 5 is a perspective view thereof. 6 is a front view showing a modified example of the developer circulation conveyance means, and FIG.
The figure is a front view showing still another modification. 1 is an image carrier, 2 is a magnet roller, 3 is a developing sleeve, 4 is a blade, 5 and 6 are screws, 7 is a partition plate,
20 is a tray, D is a developer, C is a carrier, and T is a toner.

Claims (1)

[Claims] (1) A developer carrier is fixedly arranged with a predetermined gap from the surface of the image carrier, and a magnetic field generating means is rotatably provided inside the developer carrier, and the magnetic carrier and insulating toner are heated. The two-component developer is conveyed by the magnetic force of the magnetic field generating means in a direction opposite to the rotational direction of the two-component developer toward the development region facing the image carrier, and the developer is transferred to the image carrier. In a developing device that performs development in contact with the developer, a developer regulating plate is provided near the image carrier and spaced apart from the developer carrier, and between the developer regulating plate, the image carrier, and the developer carrier, there is a A stable developer reservoir is formed, and the two-component developer 411 is stirred and mixed with the magnetic carrier and the insulating toner in a part of the "two-component developer 411 carrier" under the influence of the magnetic force of the magnetic field generating means. A developer circulation conveyance means is provided which circulates the shaft of the developer carrier in nine directions, and this developer circulation conveyance means supplies the agitated JI'+S developer to the developer reservoir. A developing device with J characteristics.