JP2002244437A - Developer carrying device and developing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a developer carrying device capable of supplying a required satisfactory amount of toner near a nip part between a supply roller and a developing roller by using a non-magnetic one-component developer and controlling the biting amount of the supply roller by a horizontal member brought into contact with the supply roller, and to obtain a developing device using the developer carrying device. SOLUTION: As for the developer carrying device, the developer is triboelectrified and carried by bringing the supply roller 3 and the developing roller 5 into contact with each other and rotating them so that they may move in counter directions at the contact part. A developer supply path from the supply roller 3 to the developing roller 5 is opposite to the gravity, and the horizontal member 4 abuts on the bottom part of the supply roller 3, and the biting amount of the supply roller 3 by the horizontal member 4 is controlled to be >=0 mm and <0.3 mm. It is preferable that the nip width of the supply roller 3 to the developing roller 5 is 4 mm to 6 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer conveying device mounted on an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile and the like, and a developing device using the same. The present invention relates to a developer conveying device using a component developer and a developing device using the same.

[0002]

2. Description of the Related Art A non-magnetic one-component type using a non-magnetic one-component developer is one type of a developer conveying device and a developing device provided in an electrophotographic image forming apparatus such as a copying machine, a printer and a facsimile. There is. This developing method has a supply roller and a developing roller, and by rotating these rollers while making contact with each other, the developer is conveyed while being frictionally charged, and is transferred to the surface of the photoconductor on which an electrostatic latent image is formed. The developer is supplied from the developing roller, and the charged developer is made to adhere to an electrostatic latent image on the surface of the photoreceptor to be visualized. The non-magnetic one-component developing device does not have a carrier for transporting a developer (hereinafter, referred to as “toner”), and therefore, the chargeability and toner transportability of the toner are inferior to those of the two-component developing method. If transportation is insufficient,
A phenomenon of a decrease in image density on the developed photoreceptor is observed.
In particular, in the development of graphic patterns and the like, since there are many so-called solid images, stabilization of toner conveyance is an essential condition.

Therefore, a configuration is often adopted in which the developing bias applied to the developing roller and the supply bias applied to the supply roller have a predetermined potential difference so that the toner is electrically carried on the developing roller and transported. . In addition, the supply roller increases in hardness with time, and changes in physical properties such as shrinking of the outer diameter, and the toner transportability is reduced, so that the solid image density is easily reduced. A configuration is also known in which the bias voltage applied to the supply roller is variably controlled to ensure toner transportability.

However, an image forming apparatus such as a copying machine often employs a toner cartridge replacement method. When a new toner and an old toner are replaced by replacement of a toner cartridge, the toner charging property fluctuates. Inconveniences, such as a decrease in the concentration of, occur. Such a decrease in solid image density when replacing the toner cartridge
As described above, this cannot be solved only by variably controlling the bias voltage applied to the supply roller according to the change in the physical properties of the supply roller.

Accordingly, the present applicant has applied a bias applying means for applying the developing bias voltage Vb to the developing roller and applying the bias voltage Vsp to the supply roller, and controlling the potential difference | Vb-Vsp | of the bias voltage to be variable. Means for controlling the potential difference | Vb-Vsp | when a solid image is output after toner cartridge replacement.
A patent application was previously filed for a developing device and a method of transporting a developer in which the toner is stably transported by increasing the toner density and a good solid image is obtained. JP-A-2000-
That is the invention described in Japanese Patent Publication No. 112212.

Further, as described in JP-A-5-88536, a conductive metal member is brought into contact with a supply roller for supplying toner to a developing roller, and a bias voltage is applied to the metal member. A developing device has also been proposed that can increase the adhesion of toner to a supply roller and improve the ability to transport a developer.

[0007]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 2000-1
In the invention described in Japanese Patent No. 12212, the supply roller and the developing roller rotate so as to be opposite to each other at both contact portions, thereby frictionally charging the toner. In such a configuration, the degree of the effect depends on the amount of toner supplied to the vicinity of the nip portion between the two rollers and the contact width between the supply roller and the developing roller. In some cases, the effect of controlling the potential difference of the bias voltage between the supply roller and the developing roller cannot be sufficiently obtained.

The above-mentioned Japanese Patent Application Laid-Open No. Hei 5-88536 describes that a conductive metal member is brought into contact with a supply roller and a bias voltage is applied to the metal member. There is a description that the contact depth (the amount of bite) is 0.5 mm or more and 2 mm or less, but at such a contact depth, the passage of the toner adhered to the supply roller surface and conveyed is prevented by the conductive metal member. May not be suitable for practical use. Further, the application of the bias voltage to the conductive metal member has a function of electrically retrieving the toner confined in the supply roller by pressing the conductive metal member against the supply roller made of a sponge-like material. It does not have a noticeable effect.

The present invention has been made in view of the above prior art, and uses a non-magnetic one-component developer so that a supply roller and a development roller are moved in opposite directions at the contact portion while being in contact with each other. A developer transport device that transports the developer while frictionally charging the developer, and a developing device using the developer transport device. The developer transport device regulates the amount of biting of the horizontal member into contact with the supply roller by the supply roller. Accordingly, it is an object of the present invention to provide a developer conveying device capable of supplying a necessary and sufficient amount of toner near a nip between a supply roller and a developing roller, and a developing device using the same.

Another object of the present invention is to provide a sufficient amount of toner between the supply roller and the developing roller by defining a nip width between the supply roller and the developing roller, To allow the toner transported near the nip to be consumed without excess or shortage,
It is an object of the present invention to provide a developer conveying device capable of forming a good image without a decrease in density even when a solid image is output, and a developing device using the same.

[0011]

According to the first aspect of the present invention,
A developer transport device that transports the developer while frictionally charging the developer by rotating the supply roller and the development roller so as to move in opposite directions at the contact portion while using a non-magnetic one-component developer while making the supply roller and the development roller contact each other. The developer supply path from the supply roller to the developing roller is opposite to gravity, a horizontal member is in contact with the lower part of the supply roller, and the amount of penetration of the horizontal member into the supply roller is Is 0 mm or more and less than 0.3 mm.

According to a second aspect of the present invention, in the first aspect, a nip width of the supply roller with respect to the developing roller is set to 4 mm to 6 mm.

[0013] The invention according to claim 3 is the invention according to claim 1 or 2.
A developing device using the developer transport device according to the above, having a photoconductor on which an electrostatic latent image is formed, and a surface of the photoconductor,
The developer is supplied from a developing roller of the developer transport device.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a developing device according to an embodiment of the present invention. In FIG. 1, a toner supply port 1 is formed in the upper left portion of the toner hopper 7, and a non-magnetic one-component toner is supplied from a toner cartridge (not shown) through the toner supply port 1 according to the remaining amount of toner in the toner hopper 7. Is to be replenished. The agitator 2 is provided in the toner hopper 7. The agitator 2 is driven to rotate in the counterclockwise direction in FIG. 1 and functions to send out the toner to the vicinity of the supply roller 3 while stirring the toner in the toner hopper 7.

The supply roller 3 has a sponge-like member having elasticity on the outer periphery. The supply roller 3 is positioned diagonally above and to the right of the movement locus of the agitator 2 in FIG. 1 and is separated from the agitator 2 and is driven to rotate counterclockwise.
A horizontal member 4 is in contact with the supply roller 3 with a predetermined bite amount on the outer periphery of the lower portion of the supply roller 3, and thereby has a function of controlling the toner conveyance amount and a function of holding the toner at the tip of the bite portion. ing. A developing roller 5 is disposed on the right side of the supply roller 3 in FIG. 1, and the outer periphery of the supply roller 3 is in contact with the outer periphery of the development roller 5. The toner conveyed to the vicinity of the supply roller 3 by the rotation of the agitator 2 is conveyed to the contact portion between the supply roller 3 and the developing roller 5 while being controlled by the horizontal member 4 with the rotation of the supply roller 3. Has become. Therefore, from the supply roller 3 to the developing roller 5
In FIG. 1, the toner supply path is obliquely upward and rightward, that is, opposite to gravity.

As described above, while the supply roller 3 is driven to rotate counterclockwise, the developing roller 5 is also driven to rotate counterclockwise. Therefore, the supply roller 3 and the developing roller 5 are rotationally driven so as to move in opposite directions at the contact portion. Therefore, the toner conveyed to the contact portion between the supply roller 3 and the developing roller 5
And the developing roller 5, is charged to a predetermined charge amount, and electrostatically adheres to the surface of the developing roller 5.

In FIG. 1, a doctor roller 6 is disposed diagonally below and to the left of the developing roller 5, and the outer periphery of the doctor roller 6 and the outer periphery of the developing roller 5 are in contact with each other. The doctor roller 6 thins the toner adhered to the surface of the developing roller 5 to form a thin toner layer suitable for developing an electrostatic latent image on the surface of the photoconductor (not shown). The photoreceptor is disposed close to the developing roller 5, and the toner attached to the surface of the developing roller 5 adheres to the electrostatic latent image on the surface of the photoreceptor, whereby the electrostatic latent image is developed and visualized. You. This development step is one step of an electrophotographic process, after which an image is formed on the transfer paper through a transfer step to a transfer paper and a fixing step, and the photoreceptor after the transfer step is a cleaning step, a charging step, An electrostatic latent image is formed again through an exposure step and the like.

The toner cartridge is replaceable. Also, as explained in the section of the prior art,
It is assumed that a supply bias is applied to the supply roller 3 and a development bias is applied to the developing roller 5. The horizontal member 4 may be a metal plate, and a bias voltage may be applied to the horizontal member 4. These bias voltages may be appropriately controlled according to various conditions, or the difference between the supply bias voltage and the development bias voltage may be appropriately controlled.

As described above, the horizontal member 4 that contacts the supply roller 3 is moved from the toner hopper 7 to the supply roller 3.
It has a function of controlling the amount of toner passing through the lower part and a function of holding it. Here, it is conceivable that the amount of bite between the supply roller 3 and the horizontal member 4 greatly affects the amount of toner transported. An experiment was conducted on the relationship between the bite amount and the toner transport amount, and the data shown in FIG. 2 was obtained. As can be seen from FIG. 2, the supply roller 3 of the horizontal member 4
The larger (deeper) the amount of penetration into the toner, the more the amount of toner passing through, that is, the amount of toner passing from the toner hopper 7 to the developing roller 5 is suppressed, and conversely, the smaller the amount of penetration, the greater the amount of toner passage. . On the other hand, from another viewpoint, i.e., the hazard that the toner receives, the deformation of the supply roller 3 is preferably small, and the amount of bite is zero.
mm. Also, from the viewpoint of toner transport efficiency, it is desirable that the bite amount is 0 mm. Here, the bite amount of 0 mm means that the supply roller 3
And the horizontal member 4 are in contact with each other, but the contact pressure is zero.

As described above, the supply roller 3 and the horizontal member 4
There are two reasons not to make contact non-contact. One is the problem of transport efficiency. By rotating the supply roller 3 while contacting the horizontal member 4 at all, toner can be transported along the horizontal member 4. On the other hand, if the supply roller 3 and the horizontal member 4 are not in contact with each other, the supply roller 3 simply rotates in a dark state, so that the supply roller 3 idles, and the toner conveyance efficiency is reduced.

The second reason why the supply roller 3 and the horizontal member 4 are not brought into non-contact is to prevent agglomerates of the toner from flowing into the development area. The presence of toner aggregates not only hinders formation of a uniform toner layer due to triboelectric charging, but also causes clogging of the nip between the doctor roller 6 and the developing roller 5, causing toner thinning on the peripheral surface of the developing roller 5. Layer loss occurs in the circumferential direction, and white streaks in the vertical direction occur in the image developed with the toner. In order to prevent such white streaks from occurring, it is sufficient to adopt a configuration that can prevent the intrusion of the toner aggregates into the development area. For this purpose, it is effective to bring the supply roller 3 into contact with the horizontal member 4. It is. Further, if the supply roller 3 and the horizontal member 4 are kept in contact with each other, the toner agglomerates are crushed at the contact portion, so that it is effective to prevent the toner agglomerates from entering the developing area.

In the developer conveying device shown in FIG. 1 and the developing device using the same, the supply roller 3 and the developing roller 5 rotate so as to move in opposite directions at both contact portions to frictionally charge the toner. It has become. In such an apparatus, in order to efficiently and efficiently adhere the toner to the peripheral surface of the developing roller 5, toner supply, frictional charging,
In addition, a sufficient nip width between the supply roller 3 and the developing roller 5 is required to allow electrostatic toner to adhere to the peripheral surface of the developing roller 5. Here, the nip width is a contact width in the rotation direction of each of the rollers 3 and 5.
As a result of an experiment while changing the nip width, it was found that the nip width was required to be at least 4 mm, and more preferably 6 mm.

FIG. 3 shows an embodiment of a developer conveying device and a developing device using the same according to the present invention. The developing roller 5 having a diameter of 26 mm has a diameter of 19 mm.
This is an example in which the supply roller 3 is brought into contact. By making the supply roller 3 bite into the developing roller 5 by 1 mm,
The supply roller 3 and the developing roller 5 were brought into contact with each other so that a nip width of about 5 mm was generated. Further, the supply roller 3 was brought into contact with the horizontal member 4 such that the amount of biting of the supply roller 3 into the horizontal member 4 was 0 mm or more and less than 0.3 mm. When an image was formed using the developer conveying device in which each part was set and the developing device using the same, a stable image was obtained even after a lapse of time, and even if a solid image was continuously formed, Sufficient toner replenishment was performed, and a good image without density unevenness could be obtained.

[0024]

According to the first aspect of the present invention, by using the non-magnetic one-component developer, the supply roller and the developing roller are rotated so as to move in opposite directions at the contact portion while making contact with each other. In a developer conveying device that conveys the developer while frictionally charging the developer, a horizontal member is brought into contact with a lower portion of the supply roller, and a bite amount of the horizontal member into the supply roller is set to 0 mm or more and less than 0.3 mm. It becomes possible to supply a necessary and sufficient amount of developer near the nip between the developing roller and the supply roller.
Therefore, when a developing device is configured using such a developer transport device, a good image without a decrease in density or unevenness in density can be obtained.

According to the second aspect of the present invention, in the first aspect of the present invention, the nip width between the supply roller and the developing roller is set to 4 mm to 6 mm, so that the direction in which the supply roller and the developing roller move in opposite directions at the mutual contact portion. 2. A sufficient amount of the developer can be supplied between the supply roller and the developing roller rotating at a constant speed, and a sufficient amount of the developer conveyed under the conditions described in claim 1 is consumed without excess or shortage. can do. Therefore, when a developing device is configured using such a developer conveying device, a good image without a decrease in density can be obtained even when a solid image is output.

According to the third aspect of the present invention, by forming a developing device using the developer transporting device according to the first or second aspect, it is possible to obtain a good image without a decrease in density or uneven density. In addition to this, it is possible to obtain a good image without a decrease in density even when a solid image is output.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a developer carrying device and a developing device using the same according to the present invention.

FIG. 2 is a graph illustrating a relationship between a biting amount of a supply roller with respect to a horizontal member and a toner conveying amount in a developer conveying device.

FIG. 3 is a front view showing an embodiment of the developer conveying device and a developing device using the same.

[Explanation of symbols]

 3 supply roller 4 horizontal member 5 developing roller

Claims (3)

[Claims] A non-magnetic one-component developer is used to transport a supply roller and a development roller while frictionally charging the developer while rotating the supply roller and the development roller so as to move in opposite directions at the contact portion. A developer supply path from the supply roller to the development roller is opposite to gravity, and a horizontal member is in contact with a lower portion of the supply roller; 0mm bite into roller
A developer conveying device having a thickness of at least 0.3 mm. 2. The developer conveying device according to claim 1, wherein a nip width of the supply roller with respect to the developing roller is 4 mm to 6 mm. 3. A developer conveying device according to claim 1, further comprising: a photoconductor on which an electrostatic latent image is formed, wherein a surface of the photoconductor is developed from a developing roller of the developer conveying device. A developing device to which the developer is supplied.