JPH04355475A - Developing device of image forming device - Google Patents

Abstract

PURPOSE:To arrest the turbulence of a toner layer by a foreign material penetrated into a relative position by bringing a toner layer thickness regulating member into contact with a developing sleeve so as to regularly change the relative position where the both make contact to each other. CONSTITUTION:When an electrostatic latent image reaches a developing position in which an image carrier 1 is opposed to a developing vessel 4, a toner image is formed. When the toner image reaches a transfer position shown by a blanked arrow, the toner image is transferred to a transfer material by a transfer bias applied to a transfer means. Thereafter, a part of the toner not transferred to the transfer material at the time of transfer reaches a cleaner 7, and is scraped off by a cleaning blade and accumulated in a toner storing part. To regulate the toner layer thickness on the surface of a developing sleeve 2, a layer thickness regulating roller 12 is pressed onto the sleeve 2 and rotated with a proper speed difference to the sleeve. Thus, the contact part between the sleeve 2 and the regulating roller 12 can be successively changed to prevent the staying of a foreign material.

Description

[Detailed description of the invention]

0001

[Purpose of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine or a printer, and particularly to a developing device thereof.

0002

[Prior Art and Problems to be Solved] In a well-known image forming apparatus that supplies toner to an electrostatic latent image formed on a charging surface of an image carrier to form a toner image, a developer serving as a toner supplying means is usually used. It has a configuration as shown in "Figure 6".

To briefly explain this, the figure shows only an image bearing member and a developing device of an image forming apparatus. A developing device 4 is disposed at.

The developing device 4 has an opening formed on the side facing the image carrier 1, and the sleeve 2, which is made of a non-magnetic material and houses a multipolar magnet roller therein, is inserted into the opening. is arranged opposite to the image carrier 1, and the sleeve 2 rotates in the direction of arrow b.

A regulating member 3 made of an elastic material such as urethane rubber or silicone rubber is in contact with the sleeve 2 at a linear pressure of 10 to 100 g/cm.

With this configuration, the toner in the developing device 4 is rolled by the rotation of the sleeve 2 and sequentially moves toward the regulating member 3, becomes electrically charged by friction with the sleeve, and is further charged by the regulating member 3. The toner is charged due to friction and the thickness of the toner is regulated, reaching the development area where the sleeve 2 and the image carrier 1 closely face each other, and the electrostatic latent image formed on the surface of the image carrier 1 by this time A toner image is formed by adsorption.

[0007] In a developing device having such a structure, since the regulating member for regulating the toner layer thickness is in fixed contact with the sleeve, toner particles with a particle size much larger than the average toner particles are produced in the corresponding contact area. When foreign matter arrives or the toner that stays at the contact area coagulates and solidifies, this prevents the toner from passing smoothly, and the desired toner layer is not formed in the area, and in extreme cases, the sleeve Multiple streaks may appear in the top toner coating. Furthermore, the toner particles that stay in the contact area may rub too much against the sleeve surface and acquire an excessive charge, or the toner surface may be destroyed and its properties may deteriorate, resulting in particles that do not retain the desired charge. There is a possibility that the toner charge becomes non-uniform, leading to image defects such as background fog and insufficient density.

The present invention has been made to deal with such a situation, and avoids the above-mentioned drawbacks by sequentially changing the contact area between the sleeve and the regulating member that contacts the sleeve. The object of the present invention is to provide a developing device that can always form a good toner coating on the sleeve surface.

[0009]

[Structure of the invention]

[Technical Means for Solving the Problems and Their Effects] In order to achieve the above object, the present invention provides a developing sleeve that conveys toner in a developing device to a developing site, and a developing sleeve that contacts the sleeve to increase the thickness of the toner layer on the sleeve surface. The developing device of the image forming apparatus is provided with a regulating member for regulating the toner layer thickness, and is characterized in that a contact portion between the sleeve and the toner layer thickness regulating member is constantly changed.

With this configuration, it is possible to prevent the toner layer from becoming irregular due to foreign matter entering between the sleeve and the toner layer thickness regulating member, thereby effectively preventing the occurrence of image quality deterioration.

[0011]

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows an embodiment of the present invention. This figure shows a cartridge-type device that can be attached to and detached from an image forming apparatus body (not shown) in any state.

The surface of the image carrier 1 rotating in the direction of arrow a is uniformly charged by a temporary charger 8, and an image signal 10 such as an image-modulated laser beam is applied to this charged surface to generate an electrostatic latent. An image is formed.

When this electrostatic latent image reaches the developing area where the image bearing member 1 and the developing device 4 face each other, toner is supplied from the developing device through the developing sleeve 2 and adheres to the latent image to form a toner. An image is formed.

Next, when this toner image arrives at the transfer site indicated by the white arrow, a transfer material (not shown) is conveyed and supplied to the site, and a transfer bias is applied to a transfer means such as a transfer charger. The toner image is transferred to the transfer material.

Thereafter, the transfer material carrying the toner image is conveyed in the illustrated manner and reaches a fixing site (not shown), and some of the toner that was not transferred to the transfer material during transfer reaches the cleaner 7 and is removed by the cleaning blade. scraped off by 5,
The scoop sheet 6 accumulates the toner in a toner reservoir within the cleaner.

Further, as the image carrier 1 advances, the residual charge on the image carrier is removed by the pre-exposure 9, and the image carrier becomes ready for the next image forming process.

In such an apparatus, in order to regulate the toner layer thickness on the surface of the developing sleeve 2, the sleeve 2 is equipped with a layer thickness regulating roller 12 of 30 g, which can be made of an elastic material such as urethane rubber or silicone rubber. The sleeve is pressed against the sleeve with a linear pressure of about 1/2 cm, and is rotated at an appropriate speed difference with respect to the sleeve. Note that reference numeral 13 is a sealing member for preventing toner leakage.

The regulating roller 12 is not limited to the above-mentioned materials, and various materials can be used depending on the charging series with the toner, and its structure can also be as follows:
Sleeves with one layer as a whole, and ones with a solid layer superimposed on the surface of a sponge layer can be used.In short, the sleeve 2
It is preferable that the nip portion between the toner and the toner be properly set so that an appropriate charge can be applied to the toner. Further, as the roller, it is also possible to use a metal roller in contact with the sleeve with light pressure.

With this configuration, the contact area between the sleeve 2 and the regulating roller 12 changes sequentially, so that foreign matter arriving at this contact area can be prevented from staying at this position, and the contact area between the sleeve 2 and the regulating roller 12 is constantly changed. A uniform toner coating can be formed on the sleeve surface.

The regulating roller 12 may be driven by the sleeve 2 or may be driven separately. Looking at the difference in the effect due to the speed difference between the two, when both are at the same speed, the toner is charged and the nip portion is Assuming that the function of preventing the accumulation of toner, foreign matter, etc. is being performed appropriately, increasing the speed of the regulation roller will increase the ability to remove foreign matter, and in the opposite case, the ability to charge the toner will improve. . Therefore, in reality, it is sufficient to set the optimum speed for each of the toner, sleeve, etc. based on their characteristics.

"FIG. 2" is a perspective view of the main part showing another embodiment, in which a developing sleeve 2 is disposed close to the image carrier 1, and a pair of drive rollers provided near the developing sleeve 2. 16,
16, an endless belt 15 made of urethane rubber film is suspended over substantially the entire length of the developing sleeve 2 and is run in the direction of arrow C in the figure. belt 15
In addition to the urethane rubber mentioned above, PVDF is also used as the material.
, polyimide, aluminum, SUS, phosphor bronze, etc.
5, it is preferable to use a material with appropriate surface friction and give it an appropriate surface shape.

A backing member 14 is disposed inside the belt 15 to press the belt 15 against the developing sleeve 2, and the belt 15 is brought into contact with the sleeve 2 with an appropriate pressure with an appropriate nip width so that the surface of the sleeve is With the toner layer formed, it reaches the development site.

With this configuration, as in the case of the above-described embodiment, foreign matter that arrives at the position of the belt as a toner layer forming means is immediately discharged to the outside as the belt runs, thereby avoiding the above-mentioned drawbacks. can. Furthermore, since this device uses the backing member 14 to press the belt 15 into contact with the sleeve 2, the nip width between the belt and the sleeve can be set freely, so the toner charging function can be achieved with a relatively small configuration. It is possible to improve.

"FIG. 3" is a side view of main parts showing another embodiment, and in this device, a pair of rollers 16, 1
6, a belt 15 is attached to the belt 15, and the belt 15 is wound up at an appropriate speed in the direction of the arrow d, and the belt 15 is wound with an appropriate pressure and nip width by a backing member 14. The sleeve 2 is configured to be pressed into contact with the sleeve 2.

With this configuration, a homogeneous toner layer is always formed on the surface of the sleeve that advances to the developing area, and foreign matter that enters the nip is removed by the running belt 1.
5 to the outside, it is possible to avoid the above-mentioned drawbacks caused by foreign matter.Furthermore, since the contact surface of the belt 15 to the sleeve is sequentially moved, foreign matter caught by the belt at the nip portion can be discharged to the outside. It is possible to reliably prevent a situation in which foreign matter remains as it is and adversely affects the formation of a toner layer on the sleeve thereafter.

"FIG. 4" shows still another embodiment of the present invention, and the figure basically shows the above-mentioned known device ("FIG. 6").
''), and is a perspective view of the image carrier, the developing sleeve, and the layer thickness regulating member 3 seen from the inside of the developing device, and the regulating member 3 is made of a urethane rubber sheet or other material in each of the above-described embodiments. The same material as the roller, belt, etc. for regulating the toner layer thickness can be used.

In the illustrated device, it is assumed that the regulating member 3 is reciprocating in a direction perpendicular to the axial direction of the sleeve 2, as indicated by the symbol e, using an appropriate cam, link mechanism, etc. .

With this configuration, in addition to the force in the traveling direction of the sleeve, a force in the e direction is applied to foreign objects that reach between the sleeve 2 and the regulating member 3, causing them to bite into the regulating member. Since it promotes the rolling of foreign matter to be used while staying at that position, it is effective in preventing the foreign matter from staying there.

``FIG. 5'' shows yet another embodiment, in which the configurations of the image carrier 1, the developing sleeve 2, and the regulating member are the same as those shown in ``FIG. 4''.

In the illustrated device, the regulating member 3 reciprocates in a figure 8 shape as indicated by the symbol f, and furthermore, between the portions indicated by the symbols f1 and f2 at both ends of the reciprocating motion,
That is, the sequence is set so that the time when the displacement direction of the regulating member 3 becomes opposite to the traveling direction b of the sleeve 2 occurs between the sheets of the transfer material.

With this configuration, the regulating member 3 can be aligned with the traveling direction of the sleeve 2 only when the development is actually performed, and the regulating member 3 can be inserted without interfering with the formation of a homogeneous toner layer. This is extremely effective in preventing the accumulation of foreign matter, as it actively provides an opportunity for the foreign matter to roll at the position of the regulating member and also tends to be actively removed.

Although the present invention has been described above with respect to a developing device in a cartridge type image forming apparatus, it is a matter of course that the present invention is not limited to such a developing device. Further, the structure in which the toner layer thickness regulating member in contact with the sleeve is displaceable as shown in "FIG. 4" and "FIG. 5" is not limited to these, and is not limited to those shown in "FIG. 1" and "FIG. 2".
It is easy to understand that the present invention can also be applied to rollers and belts such as those shown in FIG.

[0033]

As explained above, according to the present invention, in the developing device, the toner in the developing device is conveyed and supplied to the developing area via the toner layer thickness regulating member disposed in contact with the developing sleeve. Since the contact area between the regulating member and the developing sleeve is configured to constantly change, foreign matter that enters the contact area can be prevented from staying at that position and can be quickly removed to the outside. Since it can effectively prevent the toner layer from being disturbed, excessive charging of the toner, charging failure, etc. due to the presence of the toner, it has a remarkable effect in supplying a homogeneous toner layer to the development area and obtaining high-quality images.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of essential parts showing an embodiment in which the present invention is applied to a cartridge of an image forming apparatus.

[Figure 2] Partially cut slope view showing another embodiment

[Fig. 3] Side sectional view of main parts showing still another embodiment

[Figure 4] and

Claims (7)

[Claims] 1. A developing device for an image forming apparatus, comprising: a developing sleeve that conveys toner in a developing device to a developing site; and a regulating member that comes into contact with the sleeve and regulates the thickness of a toner layer on a surface of the sleeve. The developing device is configured to constantly change a contact portion between the toner layer thickness regulating member and the toner layer thickness regulating member. 2. The developing device according to claim 1, wherein the toner layer thickness regulating member is a roller that constantly rotates in contact with the sleeve. 3. The developing device according to claim 1, wherein the toner layer thickness regulating member is a belt that is conveyed so as to sequentially change the contact portion with the sleeve. 4. Claim 1, wherein the toner layer thickness regulating member is a sheet-like member that reciprocates in the axial direction of the sleeve.
Developing device as described in section. 5. The developing device according to claim 1, wherein the toner layer thickness regulating member is a sheet-like member that extends in the axial direction of the sleeve and is displaced in a figure-eight shape. 6. The developing device according to claim 5, wherein the toner layer thickness regulating member is displaced in a direction opposite to the running direction of the sleeve during a period between adjacent transfer materials. 7. The toner layer thickness regulating member is made of urethane rubber, silicone rubber, PVdF, polyimide, aluminum, S
A developing device according to any one of claims 1 to 6, which is made of a material selected from US and phosphor bronze.