JPS59135490A - Developing device - Google Patents

Abstract

PURPOSE:To enable stable and good development with a simple structure by narrowing a developing gap between a photosensitive body and a sleeve, reducing movement speed of a developer as near to (0) as possible, and preventing stagnation of a toner. CONSTITUTION:A developing gap D between a sleeve 1 and an opposite photosensitive body 4 is made as small as possible, and thickness A of a toner on a sleeve 1 is kept as equal to the gap D as possible to maintain A D. The sleeve 1 is rotated in the direction of arrow (a), and a magnet roller 2 is rotated in the direction of arrow (b), and both rtational speeds are set so as to reduce the movement speed of the toner 3 on the sleeve 1 in a developing region to zero, or as small as possible. As a result, a contact time of the toner 3 with the body 4 is lengthened, action of an electric field acting on the toner particles is made stronger, and the toner 3 is attracted to the side of the body 4 to form a toner image.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field> The present invention relates to development of an electrostatic latent image formed on a photoreceptor into a visible image in an electrophotographic copying machine. The present invention relates to a developing device that performs development using a developer made of.

<Prior art> The developing device of an electrophotographic copying machine uses a two-component developer consisting of a colored pigment toner and a magnetic carrier such as iron powder. The electrostatic latent image is charged to the opposite polarity to the electrostatic latent image, and the toner is attached to the electrostatic latent image.The other is a one-component developer in which the toner itself has magnetic properties. There is a method in which toner is electrostatically attracted to an electrostatic latent image by applying dielectric polarization or the like using the electric field of the image. A magnetic brush development method is widely used as a developing means for conveying the above-mentioned two-component or -component developer to the development area of the photoreceptor on which an electrostatic latent image is formed and attaching toner. . This development method has advantages over the cascade development method, such as a simpler structure and smaller size.The magnetic brush development method uses a cylindrical sleeve made of non-magnetic material and a Generally, a developing roller consisting of a rotatably provided magnetic throat roller is used, and by the relative rotation of the two, the carrier or magnetic toner is attracted onto the sleeve by magnetic force, and the developer is conveyed to the developing area. are doing.

The developing device having the above-mentioned structure uses a two-component developer, and requires means separate from the developing roller for stirring the developer in order to triboelectrically charge the toner.

However, those using a -component type developer do not need to provide stirring means for triboelectrically charging the toner, and can be more compact than two-component type developing devices.

By the way, various developing methods using -component type developers (hereinafter referred to as toners) are known, and developing devices that have realized these developing methods include those using conductive magnetic toner and those using insulating magnetic toner. It is well known to use However, conductive magnetic toner has a drawback that the transfer efficiency is low when electrostatic transfer using corona discharge or the like is performed, and therefore insulating magnetic toner is often used.

As mentioned above, various proposals have been made for developing devices using insulating magnetic toner, but the problem is the stability of the image. Factors that affect development include, for example, the width and time of contact between the first toner layer and the photoreceptor (=development time), and the size of the development gap (distance between the photoreceptor and sleeve) relative to the thickness of the first layer. , and the conveyance of developer sleeves. This has the disadvantage that the electrical resistance of the developer is high (indeed, this has an even greater effect, resulting in unstable development and making it impossible to obtain good images).

On the other hand, for example, in JP-A-54-1162'33, a magnet roll and a non-magnetic sleeve are rotated in the same direction, and the non-magnetic sleeve is rotated while the magnetic developer is rotated on the non-magnetic sleeve. It is disclosed that development is performed by conveying in the opposite direction.

Furthermore, in JP-A-55-126266, semiconductive or insulating magnetic toner is used, and by moving a non-magnetic roll and a permanent magnet in the same direction, the magnetic toner is transferred to the photoreceptor in the developing section. It is disclosed that development is performed by moving the photoreceptor in the same direction and at a speed of less than +00 mm/sec regardless of the speed of movement of the photoreceptor.

According to the development device described above, the above-mentioned drawbacks are alleviated, but
It cannot be solved.0 Also, the electrical resistance of the developer is 10.
150・m or more, the above-mentioned problem becomes noticeable in the above-mentioned developing device. <Objective of the Invention> In view of the drawbacks of the conventional developing device, the present invention provides a simple and stable structure without forming toner pools. The purpose of the present invention is to provide a developing device capable of performing good development.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a specific example of a developing device according to the present invention. In the figure, 1 is a cylindrical sleeve made of a non-magnetic material, and 2 is a magnet roller which is rotatably provided within the sleeve and whose outer circumferential magnetic poles are sequentially magnetized in different ways, and these constitute a developing roller. Also, code 3 is the sleeve l
A one-component magnetic toner 4 held by the magnetic force of the magnet roller 2 on top is rotated in the direction of the arrow and positioned through the layer of the sleeve 1 and toner 3 to form a drum shape on which an electrostatic latent image is formed. Photoreceptor. The toner 3 is collected in a replenishment hopper 5, and flows through an inclined plate 8 having an inclined surface with an angle R provided at the open lower part of the door 5.
It is sequentially supplied onto the sleeve 1 by the magnetic force of the magnet roller 2.

On the other hand, a developing area facing the photoreceptor drum 4 and a flopper 5
A regulating plate 6 is arranged between the sleeve 1 and the sleeve 1 at an interval of fat for regulating the amount of spikes (holding amount) of the toner 3 supplied onto the sleeve 1. The regulation plate 6 is
The amount of toner 3 magnetically attracted onto the sleeve 1 is controlled in order to always convey a constant amount of toner to the development area where the toner 3 comes into contact with the surface of the photoreceptor drum 40. Therefore, a constant amount of toner 3 is always held on the sleeve 1,
This toner layer thickness A is the thickness of sleeve l and magnet roller 2.
remains constant while rotating.

Here, the distance between the sleeve 1 and the opposing photoconductor 4 is the development gap In, and the thickness of the sleeve 1 is A and A''; D.
When provided in this relationship, the toner 3 becomes difficult to reach the photoreceptor.

In this regard, in the present invention, the direction of rotation of the sleeve 1 is in the direction of arrow a,
The magnetic rollers 2 are rotated in the same direction as shown by the arrows, and the rotational speed k (V3 ), rotation speed of magnet roller 2 ~
(■O) as appropriate. In addition, the developing gap D should be made as narrow as possible, and the thickness A of the toner on the sleeve 1 should be kept as narrow as possible.
;D relationship is maintained. This is photoconductor 4 and sleeve 1
The strength of the electric field formed between the photoreceptor 4 and the photoreceptor 4 is increased, and the force of attraction toward the photoreceptor 4 is increased. The above development gap D is O
, bn+n to 0.5 cylinders, but preferably 0.4 mm or less, and if it exceeds 0.5 mm f, the electric field strength becomes small and the suction force of the toner 3 becomes weak, which is not preferable. Also, due to the relationship between the toner layer thickness AbA, the same value will be obtained.0 In the above-described configuration, if the toner layer thickness A becomes thicker, the lower layer portion where the toner is in contact with the sleeve 1 will be The surface portions not in contact with the sleeve 1 are separated and moved in the opposite direction to the arrow direction by the rotation of the magnet roller 2. Since the two toner layers formed in this way have opposite toner transport directions, the toner particles are subjected to considerable pressure and are likely to aggregate, which will impede the transport of the toner 3. In addition, since it is difficult to reduce the moving speed of the toner 3 in the sleeve 1'' to zero in the development area, the toner layer thickness A is made thinner, and the toner layer 30 forms two layers. ＜It must be done.

On the other hand, the number of rotations of sleeve 1 (■8) and magnetic roller 2
Is it about the number of rotations (■,)? - For example, JP-A-55
A general formula for calculating the toner movement speed is presented in Publication No. 126266 and in ``Magnet Application in Electronic Copying Machines'' in Vol. 4, Journal of the Japanese Society of Applied Magnetics.

However, the characteristics of toner, such as magnetic characteristics (residual magnetic flux density,
What is the value calculated from the general formula and the actual measurement based on the holding force), particle size distribution, particle shape and surface condition (friction coefficient), electrical properties (electrical resistance, triboelectric charging properties), and the surface roughness of the sleeve 10? It didn't necessarily match. Therefore, the inventor also referred to the general formula and determined the number of rotations of the sleeve 1 (■8) and the number of rotations of the magnetic inner roller 2 (V, i I asked for it.

As described above, by narrowing the development gap D (the distance between the sleeve 1 and the photoreceptor and placing it in the development area), the moving speed of the toner 3 on the sleeve 1 is reduced to zero as much as possible. The time during which the toner 3 is in contact with the photoreceptor 4, that is, the development time, becomes longer, and the electric field acting on the toner particles becomes stronger, so that the toner 3 is attracted to the photoreceptor 4 side and forms a toner image. In this case, toner 3 is mixed with each other and with each other.
An electric charge is obtained by friction with the node l, but JP-A-53-31
It is not a rapid and turbulent movement like that in Publication No. 136 (1)
It was verified that the amount did not contribute to development.

Regarding the electrical resistance of the toner 3, FIG. 2 is a cross-sectional view when the electrical resistance was measured by bringing the developing roller into contact with an electrode plate. The symbols are almost the same as in Fig. 1, 9 is an electrode plate, 10 is a DC power source) 1 Irresistance meter (
Horizontal tube manufactured by Hule Noto Hackard 4329A), electrode plate 9
and the gap Gfl of sleeve 1 was made equal to the thickness of the toner layer. Sleeve 1, magnet, and troller 2 rotate in the same direction,
The respective rotational speeds (V8) (VM) are set so that the moving speed of the toner 3 on the sleeve l becomes zero as much as possible in the area where the electrode plate 9 and the toner 3 layer contact each other, as shown in FIG. . In this state, a DC voltage is applied between the electrode plate 9 and the sleeve 1 to read the resistance value.

Next, one embodiment of the invention will be described.

The developing roller is placed opposite the photoreceptor 4 with a developing gap D'fc 0.3 m+n in between, and the regulating plate 6 and the sleeve 1 are arranged so that the thickness A of the toner on the sleeve l becomes A dust.
The interval B t O,2wn was maintained. The McNet roller 2 in the sleeve 1 has 600 square poles with 16 poles, rotates in the same direction at the sleeve rotation speed V3 = 30 rprn, and the McNet roller rotation speed VM = 70 Orpm. The toner moving speed If was reduced to zero as much as possible. At this time, the toner is supplied after it has been used for development. Both the sleeve and the Macnet roller are rotating, and the balance is maintained in the development area, so if the balance is disrupted, the toner can be quickly replaced. The force of trying to return to (
Toner is supplied from the hopper 5 due to the rotation of the sleeve and magnet roller.

On the other hand, the photoreceptor 4 is constructed using an organic photoconductor, and the potential of the electrostatic latent image is set to about -500V, and the toner 3 contains a total of 40% by weight of magnetite as magnetic powder in polystyrene resin. DC voltage 100-1000cm using the device shown.
The electrode plate 9 and the sleeve cap G are set equal to the thickness of the toner layer, and the sleeve rotation speed is set to V8-.
3Orpm Magnet roller rotation speed VM-70Orp
When measured at m, the electrical resistance remained constant without responding to changes in the applied voltage. Also, while maintaining the state in which the moving speed of the toner on the sleeve l is as zero as possible in the area where it contacts the electrode plate 9 with the sleeve rotation speed (■8) and the magnetic roller rotation speed (VM), (V8 ), (8) The electrical resistance did not change even when the rotational speed was increased by about 3 times. Therefore, it was found that the electrical resistance of the toner does not depend on the electric field and does not depend on the conveyance speed.

In another method, the toner was formed into a tablet and the electrical resistance was measured, and it was found to be more than 1O15 [Ω·m].

Using the above-mentioned toner, four developments were carried out.

As a result of development, a stable and good toner image was formed, and a clear image was obtained on plain paper by corona transfer.

<Effects of the Invention> According to the present invention, the developing gear is completely narrowed, the thickness of the toner layer is also made thinner, the sleeve and the Macnet roller are rotated in the same direction, and the moving speed of the toner in the sleeve 1'' in the developing area is increased by the exposure speed. Since it is made to be as low as possible regardless of the speed of movement of the body, it does not form any accumulations and can perform stable and good development.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a specific example of the developing device of the present invention. FIG. 2 is a cross-sectional view showing an example of measuring the electrical resistance of the toner used in the present invention. 1 sleeve, 2: magnet roller, 3: toner, 4
: Photoreceptor, 6: Regulating plate, A: Toner thicker. D: Distance between photoreceptor and sleeve, ■Ya: Rotational speed of magnet roller, ■8 Nisleeve rotational speed Agent Patent attorney Yoshihiko Fuku (2 others) Figure 1 Figure 2

Claims (1)

[Claims] 1. A photoreceptor on which an electrostatic latent image is formed using a one-component developer containing a magnetic material in a resin using a developing roller that has a rotatable magnet 17 roller inside a sleeve made of a non-magnetic material. In a developing device that performs development by transporting the photosensitive member and the sleeve to a developing area facing each other, the photoreceptor and the sleeve are arranged with a narrowing interval between the opposing developing areas, and the sleeve and the magnetic roller are rotated in the same direction. . A developing device, characterized in that the rotation speeds of the sleeve and the magnetic roller are set so that the moving speed of the developer in the developing area facing the photoreceptor is zero or as close to zero as possible.