JP3204740B2 - Liquid developing device for electrostatic latent images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developing apparatus for an electrostatic latent image in which charged toner particles are suspended in an insulating liquid and developed by an electric field formed between the electrostatic latent image and a developing electrode. Things.

[0002]

2. Description of the Related Art A wet developing method will be described with reference to FIG. The space between the conductive developing roller 20 and the dielectric layer or the photosensitive layer 21 on which the latent image charge 24 is formed is filled with the developer 22. The developer 22 is a suspension of charged toner 23 having a polarity opposite to the latent image charge in an insulating liquid.
The charged toner 23 is attracted by the electric field by 4 and the development is performed. At this time, by short-circuiting the dielectric layer or the photosensitive layer 21 and the developing roller 20 to have the same potential, the electric field intensity E in the developing solution is increased so that effective development is performed. The electric field strength E can be increased by shortening the distance L between the dielectric layer or the photosensitive layer 21 and the developing roller 20, but if the distance L is too small, the amount of the developer 22 becomes small and sufficient. Since development becomes impossible, the optimum interval L is determined in consideration of these factors.

The liquid developing device shown in FIG. 4 includes a device using a dish developing electrode shown in FIG. 5 and a device using a rotating roller developing electrode shown in FIG. FIG. 5 shows a configuration in which a dish-shaped developing electrode 31 is arranged so as to face a cylindrical electrostatic latent image carrier 30, and a fluid developer 32 is interposed between the two. 33 applies a voltage having the same polarity as that of the electrostatic latent image to the developing electrode 31 to prevent development (fogging) on a portion where the latent image is not formed.

In the apparatus shown in FIG. 6, an application roller 40 is disposed so as to face the electrostatic latent image carrier 30, and a fluid developer is ejected toward the application roller by a nozzle-type developer supply device 41. The developer is supplied to the electrostatic latent image carrier 30 by an application roller. Alternatively, the application roller 40 may be immersed in the fluid developer 43 filled in the container 42, and the developer may be supplied by rotating the roller.

[0005]

In the apparatus shown in FIG. 5, a bias voltage is applied to prevent development of a portion where an electrostatic latent image is not formed. There is a problem that the toner is electrodeposited on the surface of the electrode 31 to reduce the electrode effect, and in particular, the toner accumulates at a low position as indicated by reference numeral 34. The toner accumulated on the side of the developing electrode can be moved to the electrostatic latent image carrier 30 by applying a reverse bias voltage for a certain period of time after the end of the development until the start of the next development, and removed by a cleaner. However, when it is dried and solidified on the electrostatic latent image carrier 30,
Cleaning at startup is not easy. The development is promoted as the developing electrode 31 is closer to the electrostatic latent image carrier,
The amount of the developer decreases, and if it is too close, the developer forms a meniscus between the developing electrode and the electrostatic latent image carrier and cannot be discharged, and if it is dried and solidified, cleaning becomes difficult. There is.

Further, in the apparatus shown in FIG.
However, when the developing device is arranged laterally with respect to the electrostatic latent image carrier 30 or when the space is narrow, it is necessary to uniformly form the developing solution on the roller surface. And it is difficult to uniformly supply the developer to the surface of the electrostatic latent image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to reliably remove a developer electrodeposited on a developing electrode, to provide a high degree of freedom in arrangement of a developing device, and to reduce the size. It is an object of the present invention to provide an electrostatic latent image liquid developing device capable of supplying a developing solution uniformly to an electrostatic latent image surface.

[0008]

According to the present invention, there is provided a liquid developing apparatus for developing with a rotating roller developing electrode using a wet type developer, wherein a developing solution is supplied to an electrostatic latent image carrier on which an electrostatic latent image is formed. An application roller, a nozzle or a slit disposed close to the application roller for ejecting the developer to the surface of the application roller, and a developer supply unit for uniformly forming the developer on the application roller surface. And The present invention is further characterized in that a DC bias power supply for applying a forced bias voltage to the application roller and an AC bias power supply for applying an AC bias voltage between the application roller and the developer supply unit are provided.

[0009]

According to the present invention, an application roller for supplying a developing solution to an electrostatic latent image surface and a means for uniformly forming a developing solution on the application roller surface are provided, so that the developing solution is uniformly formed on the application roller surface. As a result, the supply of the developing solution to the electrostatic latent image surface is made uniform, and a forced DC bias is applied to the application roller.
Applying an AC bias between the application roller and the developer supply means prevents development of the portion where the electrostatic latent image is not formed, and ensures that the electrodeposited developer on the application roller is not in contact Can be removed.

[0010]

1 is a view showing one embodiment of a liquid developing apparatus according to the present invention. In the drawing, reference numeral 1 denotes an electrostatic latent image carrier, 2 denotes an application roller, 2a denotes a blade, 3 denotes a measuring roller, and 4 denotes a liquid. The developer 5 is a squeeze roller, 11 is an AC bias power supply, and 12 is a DC bias power supply. Electrostatic latent image carrier 1
Has an electrostatic latent image formed imagewise on the surface, and rotates in the direction of the arrow. The application roller 2 rotates without contacting the electrostatic latent image carrier 1 and supplies the developer to the electrostatic latent image surface. The metering roller 3 comes into contact with the liquid developer and approaches or contacts the application roller 2 to form a uniform developer on the roller surface. The squeeze roller 5 disposed close to the electrostatic latent image carrier 1 is for scraping off excess solvent.

In such a configuration, an electric field generated by the electrostatic latent image is formed between the electrostatic latent image carrier 1 and the application roller 2, and the charged toner in the liquid developer 4 is transferred to the electrostatic latent image surface. And development is performed. At this time,
A DC bias voltage having the same polarity as that of the electrostatic latent image is applied from a bias power supply 12 to the application roller 2, and a portion of the electrostatic latent image carrier 1 where the electrostatic latent image is not formed is prevented from being developed so that the residual potential is reduced. Prevents fogging. Therefore, the developer is electrodeposited on the application roller 2 in a portion where there is no electrostatic latent image. The amount of the developer supplied to the application roller 2 can be arbitrarily changed by changing the gap and the rotation speed between the application roller 2 and the measuring roller 3, so that the developer is uniformly formed on the application roller surface. Then, by applying an AC voltage between the application roller 2 and the measuring roller 3 by the AC power supply 11, the developer electrodeposited on the application roller is removed without contact by the alternating electric field, and Is also removed. It is also possible to provide the application roller 2 with a blade 2a to mechanically remove the electrodeposited toner. Further, the squeeze roller 5 is also provided with a measuring roller opposed thereto, and by applying an AC voltage between the two, the developer electrodeposited on the squeeze roller can be removed in a non-contact manner.

FIG. 2 shows another embodiment of the present invention, which is the same as that of FIG. 1 except that the surface of the application roller 6 and the measuring roller 7 are provided with irregularities. The unevenness of the roller surface may be regular or irregular, and the size of the unevenness may be arbitrarily determined in accordance with the required space between the electrostatic latent image surface and the application roller 6.
In the present embodiment, when the developer is electrodeposited on the application roller 6 by a bias voltage, the application roller 6 cannot be removed mechanically due to unevenness of the roller surface. By applying an AC voltage by means of 11, the developer electrodeposited on the application roller 6 and the measuring roller 7 can be removed in a non-contact manner by the alternating electric field.

FIG. 3 is a view showing another embodiment of the present invention, in which a nozzle for ejecting a developer as a means for supplying a developer to an application roller 2 is arranged in proximity. The developer supply device 8 has a nozzle 8a, and a pump 10
Is supplied to the application roller 2 through the nozzle 8a. Also, the developer supply device 8
Has a discharge port 8b for discharging the developer that has reached a predetermined level, and surplus developer is discharged from the discharge port 8b. When the developer supply device 8 is disposed close to the application roller and the developer is ejected from the nozzle 8a, the developer is uniformly formed on the surface of the application roller, and the developer is uniformly developed on the electrostatic latent image carrier 1. An agent can be supplied. Note that an AC voltage is applied between the inner surface of the developer supply device and the surface of the application roller 2 by the AC power supply 11, and the developer can be removed in a non-contact manner by an alternating electric field. Therefore, no problem occurs even if the roller and the developer are arranged close to each other.

[0014]

As described above, according to the present invention, the developer can be uniformly formed on the surface of the application roller, and the developer can be uniformly supplied to the surface of the electrostatic latent image to perform uniform development. By applying a forced DC bias to the application roller, fogging due to residual potential and the like can be prevented, and the developer electrodeposited on the application roller and the developer supply device can be removed in a non-contact manner by applying an AC voltage. Thus, even if the developer supply device and the application roller are arranged close to each other, it is possible to prevent a failure due to electrodeposition of the developer. Further, since the electrodeposited developer can be removed in a non-contact manner, there is no need to particularly provide a blade, so that the degree of freedom of arrangement of the developing device can be increased and the device can be made compact.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a liquid developing device of the present invention.

FIG. 2 is a view showing another embodiment of the liquid developing device of the present invention.

FIG. 3 is a view showing another embodiment of the liquid developing device of the present invention.

FIG. 4 is a diagram illustrating a wet development method.

FIG. 5 is a diagram illustrating a developing device using a dish-shaped developing electrode.

FIG. 6 is a diagram illustrating a developing device using a rotating roller electrode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrostatic latent image carrier, 2, 6 ... Application roller, 2a ... Blade, 3,7 ... Measurement roller, 4 ... Liquid developer, 5 ... Squeeze roller, 8 ... Developer supply device, 8
a: nozzle, 8b: outlet, 11: AC bias power supply,
12 DC bias power supply.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-308177 (JP, A) JP-A-51-90828 (JP, A) JP-A-52-75438 (JP, A) JP-A 47- 13946 (JP, A) JP-A-48-66846 (JP, A) JP-A-60-136778 (JP, A) JP-A-56-81870 (JP, A) JP-A-2-302765 (JP, A) JP-A-49-111637 (JP, A) JP-A-48-22038 (JP, A) JP-A-47-28932 (JP, A) JP-A-61-16565 (JP, U) JP-B-52-5855 (JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/10

Claims (2)

(57) [Claims] 1. A liquid developing device for developing with a rotating roller developing electrode using a wet developer, an application roller for supplying a developing solution to an electrostatic latent image carrier on which an electrostatic latent image is formed, and an application roller A liquid for an electrostatic latent image, comprising: a nozzle or a slit disposed close to the surface of an application roller for ejecting a developer and a developer supply unit for uniformly forming the developer on the surface of the application roller. Developing device. 2. The developing device according to claim 1, further comprising a DC bias power supply for applying a forced bias voltage to the application roller, and an AC bias power supply for applying an AC bias voltage between the application roller and the developer supply means. A liquid developing device for an electrostatic latent image.