JPS59113466A - Developing device - Google Patents

Abstract

PURPOSE:To miniaturize a developing device with reduction of jam generation rate by using a means to carry a developing agent which is moved on a developing agent carrier member in the direction opposite to the moving direction of a magnetic field generating means and passed through a developing region to the outside of a region restricted by said magnetic field. CONSTITUTION:A developing device has a nonmagnetic sleeve 3 fixed closely to a drum-shaped electrostatic latent image carrier 1. A developing agent is carried over the sleeve 3 in the direction opposite to the revolving direction of an inner magnet roller 2. In this case, a rotary blade 7 provided at the lowest part of the sleeve 13 revolves almost within a recess part 8, and the developing agent sprayed by the blade 7 is received by a screw conveyor 9 to be carried and collected in the axial direction. In such a constitution, a developing device can be miniaturized with reduction of jam generation rate.

Description

[Detailed description of the invention] The present invention relates to a latent image developing device for electrophotography and the like.

In the generally widely used magnetic brush development method, a non-magnetic sleeve containing a fixed magnet is rotated to form a brush of developer consisting of magnetic carrier and toner on the surface.
The electrostatic latent image is developed by rubbing. However, in devices using this method, the latent image is strongly rubbed with a brush, resulting in brush marks (brush marks) and so-called directional differences in density at the leading and trailing edges of the developed image, resulting in poor image quality. It is the cause of deterioration.

Furthermore, development methods using l-component magnetic toner are known today, and those using conductive toner are known as the MagneDry method, but this method is difficult to transfer the toner to the copying material, and the γ High quality and poor halftone image reproducibility.

Furthermore, various developing methods using insulating magnetic toner have been considered, but the developing characteristics tend to become unstable due to changes in temperature and humidity, and γ becomes high, making it difficult to reproduce halftones. Generally, development using magnetic toner is not suitable for color development because the toner contains a brown or black magnetic material. FIG. 1 is an enlarged view of the developing section of a conventional developing device.
The thickness of the developer layer on the developing sleeve 3 is regulated to the same extent as the distance d1 between the electrostatic latent image carrier 1 and the developing sleeve 3 by a doctor blade 4a provided close to the electrostatic latent image. A developer is brought into contact with the body 1 to develop it. However, since the developer p on the developing sleeve 3 is made up of the carrier C and the toner T in the form of a brush, the developer p is in the portion that does not come into contact with the electrostatic latent image carrier l, as shown in an enlarged view in FIG. This was not desirable as a developing device, as it was not possible to perform uniform development, and β during contact with the developer was also narrow, making it impossible to perform sufficient development.

The present invention has been made in view of the above points, and it is possible to obtain a uniform image without brush marks or directionality, to enable halftone development and color development using general non-magnetic toner, and to use a simple and compact device. The purpose of this invention is to provide a developing device.

The present invention includes an electrostatic latent image carrier, a developer supporting member provided with a gap from the latent image carrier, and rotating magnetic field generating means provided inside the developer supporting member. , a developer regulating means provided near the latent image carrier at a distance from the developer carrier member; and a developer regulating means provided near the latent image carrier, and a developer moving on the developer carrier member in a direction opposite to the moving direction of the magnetic field generating means to control the development area. The present invention is characterized in that it includes a conveying means for conveying the developer that has passed through the magnetic field to outside the restraining area, and a developer collecting means provided outside the restraining area.

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

FIG. 3 is an enlarged view of the developing device according to the present invention. A non-magnetic developing sleeve 3 is fixedly arranged in close proximity to the electrostatic latent image carrier 1, and a magnet roller 2 which is alternately magnetized with N and S poles is rotatably provided inside the developing sleeve 3. When a developer P consisting of a mixture of a magnetic carrier such as iron powder and an insulating toner that is charged with a tripod charge when it comes into contact with the magnetic carrier is supplied, and the magnetic roller 2 is rotated in the direction of the arrow, the magnet is activated. As is well known, the developer p on the surface of the magnetic roller 2 moves in a direction B opposite to the rotational direction of the magnetic roller 2 while rotating on the surface of the magnetic roller 2 . In this way, in this device, the distance d between the doctor blade 4, which is the developer regulating plate, and the developing sleeve 3 is
2 is the distance d1 between the electrostatic latent image carrier l and the developing sleeve 3.
In addition, since the doctor blade 4 is provided close to the electrostatic latent image carrier 1 and the developing sleeve 3, the gap between the electrostatic latent image carrier 1 and the developing sleeve 3 is sufficiently wide. The amount of developer P passing through the gap between L and developing sleeve 3 is limited, and the amount of developer P passing through the gap between L and developing sleeve 3 is limited.
Developer can be stored in a delta shape. At this time,
It has been confirmed through experiments that the layer no longer grows when it accumulates to approximately the tip of the doctor blade 4. Furthermore, this reservoir portion A is located between the electrostatic latent image carrier 1 and the developing sleeve 3.
It was confirmed that it is stable against changes in the distance d1 between the magnetic roller 2, the rotational speed of the magnet roller 2, the speed of the electrostatic latent image carrier 1, and the toner concentration of the developer p. Therefore, the development area α of the electrostatic image carrier 1 has a stable and constant width, and the developer p in the pooled portion A comes into contact with the electrostatic latent image carrier l while being agitated by the rotation of the magnet roller 2. , it is possible to perform sufficient development and create uniform, high-quality images. The developer p used for development is gradually discharged from the development section α in the direction of the arrow B.
Generally, toner is replenished and reused as needed. In particular, developing devices such as color copiers with good reproducibility are supplied with a developer with a constant toner concentration, and the developer used for development is collected and discarded, thereby achieving development with no change in density. It is possible to do so.

However, in the developing device, the developer must be collected and removed after passing through the developing area, or collected and reused to perform a continuous processing function. Therefore, a device shown in FIG. 4 may be considered as a mere recovery mechanism. That is, the blocking part 5 of the developer storage container 5 is brought into contact with the fixed and immovable sleeve 3 to block the developer that is continuously conveyed through the developing area on the sleeve. It is. However, since the developer is strongly restrained by magnetic force on the sleeve 3, the blocking portion 5'
Therefore, even if it is restricted, it does not fall from the sleeve 3 immediately, but the restrained thickness t gradually increases, and this thick portion grows clockwise up to a certain angle θ. Then, the developer does not grow to a certain thickness or more, and after the thickness grows up to the upstream side of a certain angle θ, the developer falls from the lowest part g by being pushed by the developer that is sent in. still,
The developer layer on the downstream side (on the blocking portion 5 side) of this falling position simply rotates on its axis on the sleeve 3 and does not undergo any metabolism with the incoming developer. Regarding the above angle θ, for example, a non-magnetic sleeve with a diameter of 32 mm and a magnetic pole of 8
750 gauss, the developer is an iron powder carrier with an average particle size of 30p- mixed with toner at a toner concentration of 12 wt% (the toner is for Canon NP color copier), and the magnetic roller 2 is rotated at 300-50 rpm. ,t',8
mm, θ＼60＠.

Therefore, even if the collecting section 6 is provided below the apparatus shown in FIG. 4 as shown in FIG. It gradually stayed there and eventually overflowed from the gap 6 between the sleeve 3 and the collecting section 6, which did not work. Of course, since the developer on the sleeve 3 is not metabolized downstream from the lowest part, it is not efficient to convey the developer in this area by the conveyor 9.

The present invention has been made in view of these points, and FIG. 6 shows a first embodiment thereof.

The developer is carried through the non-magnetic sleeve 3-H which is fixed close to the drum-shaped electrostatic latent image carrier 1 in a direction opposite to the direction of rotation of the internal magnet roller 2. A rotary blade 7 is provided substantially at the bottom of the sleeve 3 in contact with the sleeve and substantially parallel to the central axis of the magnet roller 2. The rotating blade 7 has an elastic plate 7'' provided radially on the drive shaft 7, and rotates so as to slide on the sleeve 3.The rotating blade 7 is formed at the bottom of the developer storage container 5. Approximately concave portion 8
However, since the upper part of one wall 10 of the substantially recessed portion 8 is open, the developer on the sleeve 3 that has been rubbed off is blown out of the area where it is restrained by the magnetic force of the magnet roller 2. . A screw conveyor 9 is installed in parallel with the concave portion 8 and is rotatable along the drive shaft outside the restraint area, and receives the developer blown away by the blades 7 in one rotation and conveys and collects it in the axial direction. can do.

With such a configuration, the developer recovery means can be placed anywhere, and when the rotating blade 7 and the recovery means (for example, the screw conveyor 9) are arranged side by side as in the embodiment,
The protrusion of the developer carrier 3 toward the bottom is also small, making it possible to downsize the developing device. Even if the developing device is provided on the side or above the drum-shaped latent image carrier L, the conveyance path of the transfer material P can be kept unbendable, making it possible to downsize the copying device and reduce the occurrence of jams. do. Note that 11 is a transfer charger, and 12 is a separation static eliminator.

FIG. 7 shows a second embodiment, in which a screw conveyor 13 is separately provided to the screw conveyor 9 shown in FIG. 6 with a partition wall 14 in between.

An opening 15 is provided on the back side or the front side of the partition wall, and the upper part is in contact with the sleeve 3. As a result, the recovered developer is recirculated to the developer storage section 5, where it is supplied with new developer from the replenishment container 16, stirred uniformly, conveyed over the sleeve 3, and can be used for development again. It is.

In the detailed explanation of the present invention, an example in which the developing sleeve is fixed has been shown, but the sleeve can also be used in the same manner as the magnetic roll.
If the sleeve is rotated very slowly in the direction opposite to the toner conveyance direction, without interfering with the conveyance of the entire developer, the developer near the sleeve surface will be rotated in the direction opposite to the direction of rotation of the sleeve, that is, the conveyance direction of the entire developer. It moves slightly in the opposite direction, making it easier for the developer to circulate in the developer reservoir A, allowing for good development and preventing the developer from coagulating in the developer reservoir A.

As explained above, according to the present invention, a wide and stable developing area can be formed, so proper development can be performed without brush marks or density unevenness with a magnetic brush, and the developer after development can be transferred from the developing sleeve to the magnetic field. Since the developer is moved to an out-of-reach area to ensure collection, it is possible to provide a compact developing device that can perform stable development at all times without any developer leaking from the developing device.

[Brief explanation of drawings]

1 and 2 are enlarged views of a conventional developing device, FIG. 3 is an enlarged view of a developing device according to the present invention, FIGS. 4 and 5 are explanatory views of developer recovery states, and FIG. 6 is an enlarged view of a conventional developing device. FIG. 7 is a diagram showing a first embodiment of the present invention, and FIG. 7 is a diagram showing a second embodiment of the present invention. 1-----One electrostatic latent image carrier 2---- Magnet roller (magnetic field generating means) 3--
--- Sleeve (developer carrier) 4 --- Doctor blade (developer regulating means) 7 --- Rotating blade (
Transport means) 9----Screw conveyor (developer collection means) Applicant: Canon Co., Ltd.

Claims (2)

[Claims] (1) an electrostatic latent image carrier, a developer carrier provided with a gap from the latent image carrier, and a rotating magnetic field generating means provided inward of the developer carrier; a developer regulating means provided near the latent image carrier and spaced apart from the developer carrying member; A developing device comprising: a conveying means for conveying the developer that has passed through the magnetic field to outside the restraining area by the magnetic field; and a developer collecting means provided outside the restraining area. (2) Gap d2 between the developer regulating means and the developer carrier
2. The developing device according to claim 1, wherein: is larger than the gap d1 between the latent image carrier and the developer carrier.