JPH02306275A - Developing device for electric printer of wet developing system - Google Patents

Abstract

PURPOSE:To obtain a small-sized developing device carrying out high-grade development and to prolong the service life of an image carrier by providing a developer container, a developer feed roller and a developing roller. CONSTITUTION:A liquid developer 13 is surrounded with bubbles in the feed roller 14, and is carried to the developing roller 16. Since it rotates by pressing the feed roller 14 by a prescribed amount, the developer 13 oozes out to the surface of the roller 14 to place on the roller 14 by surface tension, and is fed to a part opposite to the image carrier 11 in that condition. In such a way, a latent image on the image carrier 11 is developed. At this time, a developing bias is applied to the developing roller 16 to raise a developing efficiency. Part of the developer 13 that is used for development sticks to the surface of the carrier 11 by surface tension, and the remainder flows down along the surface of the developing roller 16. The flowing-down developer 13 is absorbed by vacant bubbles in the roller 14, and is recovered to the container 12 along the surface. In this constitution, high-grade development is attained, and the life of the image carrier can be prolonged.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a developing device for a wet-type electronic printer (printer, copying machine, etc.) that performs development using a liquid developer. In particular, the present invention relates to an improvement in means for supplying developer in a container to the surface of an image carrier.

[Prior Art] Japanese Patent Publication No. 58-30581 discloses a developer supply means using a foamed elastic roller.

FIG. 4 is a diagram showing the developer supply means cited from the above-mentioned publication. As shown in the figure, the developing roller 2 is inside the developer storage section 1.
is rotated, and the developer 3 is sucked into the foamed bubbles. By bringing the developing roller 2 into contact with the image carrier 4, the developer oozes out onto the surface of the image carrier 4, thereby performing development.

On the other hand, Japanese Patent Application Laid-Open No. 63-303379 discloses a developer supplying means using a metal roller.

FIG. 5 is a diagram showing the developer supply means cited from the above publication. As shown in the figure, a pump 6 sucks up a developer 7 from a developer storage section 5, pours it into the upper part of a developing device 8, and supplies it to developing rollers 9a and 9b. These developing rollers 9a and 9b rotate without contacting the image carrier 10. The developer 7 is supplied to the image carrier 10 by the rotation of the developing rollers 9a and 9b. Development is thus performed.

[Problems to be Solved by the Invention] The developer supply means disclosed in Japanese Patent Publication No. 58-30581 can be praised for its simple mechanism. However, since the developing roller 2 is in contact with the surface of the image carrier 4, uneven development is likely to occur depending on the degree of contact, and the surface of the image carrier 4 is likely to be damaged due to sliding contact, resulting in a shortened service life. There is a problem with doing so.

The developer supplying means disclosed in Japanese Patent Application Laid-Open No. 63-303379 is such that the developing rollers 9a and 9b are connected to the image carrier 10.
Because it is in a non-contact state with the surface of
can be extended. However, since the supply time for the developer 7 is complicated, it is disadvantageous in that it is large and expensive.

An object of the present invention is to provide a wet development type electronic printer that can supply developer well with a small and simple mechanism, enable high-quality development, and extend the life of an image carrier. An object of the present invention is to provide a developing device.

[Means for Solving the Problems] The present invention takes the following measures in order to solve the above problems and achieve the objectives. That is, the liquid developer in the developer storage container is conveyed by being contained in a supply roller or a supply belt made of an elastic material such as foamed urethane, and the conveyed developer is supplied to the developing roller. The developing roller is arranged so as to be in contact with the supply roller or the belt, and to face the surface of the image carrier with a small gap therebetween. By thus rotating the developing roller, the developer adhering to the surface of the roller due to surface tension is supplied to the surface of the image carrier, thereby performing development. After the development is completed, surplus developer remaining on the surface of the developing roller is transferred to the supply roller or belt in sliding contact and returned to the developer storage container.

In order to remove excess developer remaining on the image carrier after development, it is desirable that a squeeze roller be disposed close to the carrier and in sliding contact with the supply roller or belt.

By doing this, excess developer on the image carrier is removed and the squeeze roller itself is cleaned.

[Function] By taking the above measures, although the following effects occur, liquid developer can be stably supplied to the image carrier by a simple mechanism consisting of a combination of a supply roller or a supply belt and a developing roller. . Therefore, with a small and simple mechanism, developer can be well supplied to the image carrier, and high-quality development can be performed. Further, since the developing roller can be placed in a non-contact state with the image carrier, there is no risk of the surface of the image carrier being damaged by the surface of the developing roller, and the life of the image carrier can be extended.

[Embodiment] FIG. 1 is a sectional view showing a first embodiment of the present invention. A developer container 12 is arranged below the image carrier 11 . A liquid developer 1B is stored inside this container 12. A supply roller 14 and a squeezing roller 15 are each supported rotatably in the direction of the arrow in a state where at least a portion thereof is immersed in the developer]3. A developing roller 16 is also pivotally supported above the supply roller 14 so as to be rotatable in the direction of the arrow. This developing roller 16 covers the surface of the supply roller 14 by a predetermined amount (1,5~
3 mm), and is arranged so as to have a minute gap (0.1 to 0.3 mm) with the image carrier 11. The squeeze roller 17 has a minute gap (0.1 to 0.2
It is pivoted so that it can be rotated in the direction of the arrow with a rotation angle (mm). One end edge of a blade 18 for cleaning the surface of the squeeze roller 17 is in contact with the circumferential surface of the squeeze roller 17.

The supply roller 14 is made of an elastic material such as urethane foam that has air bubbles at least near the surface.

Further, the squeezed cola 15 is pivotally supported at a position where it crushes the supply roller 14 by a predetermined amount.

Next, the operation of the first embodiment configured as described in section 1 will be explained. When the supply roller 14 starts rotating in the direction of the arrow, the liquid developer 13 is taken up by air bubbles inside the supply roller 14 and is transported to the position of the developing roller 16 . Since the developing roller 16 rotates while compressing the supply roller 14 by a predetermined amount, the developer 13 contained in the bubbles oozes out onto the surface of the supply roller 14 . The developer 13 is supplied to the portion facing the image carrier 11 while being on the surface of the developing roller 16 due to its surface tension. Thus, the image carrier 11
The upper latent image is developed. During development, a developing bias is applied to the developing roller 16 to increase the developing efficiency. A part of the developer 13 that has been developed adheres to the surface of the image carrier 11 due to surface tension, and the remaining part is attached to the developing roller 16.
flows downward along the surface of the The developer 13 that has flowed down is either absorbed by the empty air bubbles of the supply roller 14 or
Alternatively, the developer is collected into the developer storage portion of the container 12 by passing along the surface thereof. The developer 13 absorbed by the supply roller 14 is
The developer is squeezed by a squeeze roller 15 and dispersed within the developer in the storage section. Immediately after the portion of the supply roller 14 that has passed the squeezing roller 15 , new developer 13 is sucked into the bubbles again and transported to the developing roller 16 , repeating the cycle. Supply roller 14 in the above operation
The amount of crushing is determined by the diameter of the roller 14, material 1 foaming degree 1
Determined by rotation speed etc. - For example, in the case of a low-speed machine that prints about 5 A4 size sheets per minute, the diameter of the supply roller 14 is φ.
30, and if the number of foamed cells is about 30 cells/inch, the number of crushing plates of the developing roller 16 and squeezing roller 15 is 2.
It is desirable to set it to ~4 mm.

On the other hand, the developer attached to the image carrier 11 is squeezed out to a practically sufficient extent by the squeeze roller 17 rotating in the opposite direction. The squeezed out excess developer is scraped off by the blade 18 and collected in the storage section. At this time, the height of the liquid level in the developer storage section is equal to the height of the blade 18.
must be below the point where the tip contacts the squeeze roller 17. Furthermore, it is desirable that the supply roller 14 be located at a position where it is in contact with the lowest position of the developer storage section so that the developer 13 can be sucked up to the end.

According to the first embodiment described above, the following effects are achieved.

■The developer 13 is supplied to the supply roller 14 and the developing roller 1.
6, so there is no need to use a complicated mechanism such as a pump.

■Also, since development can be performed without bringing the developing roller 16 into contact with the image carrier 11, high-quality development can be performed and the surface of the image carrier 11 is not damaged, improving durability. .

(2) Since the supply roller 14 also has the function of cleaning the developing roller 16, there is no need to provide a special cleaning means, resulting in a simple mechanism.

(2) Since the supply roller 14 is disposed at the bottom of the developer storage section, even when the developer is running low, it can be supplied to the end.

FIG. 2 is a sectional view showing a second embodiment of the present invention. In this embodiment, the squeeze section of the first embodiment is further simplified. That is, the squeeze roller 20 is arranged such that its upper portion is close to the image carrier 11 and can perform a squeezing operation, and its lower portion is placed in pressure contact with the supply roller 14 to perform squeezing. There is. It is pivoted so that it can rotate in the direction of the arrow. In addition,
The liquid level height of the developer storage section is set lower than that of the squeeze roller 20.

In this embodiment configured as described above, the operation and function of the supply roller 14 supplying the developer 13 to the developing roller 16 are the same as in the first embodiment, but the operation of removing excess developer generated after development is and have different effects.

The developer attached to the image carrier 11 that has been squeezed out by the squeeze roller 20 and the developer that has flowed into the supply roller 14 via the developing roller 16 are separated by the squeeze roller 20.
and the supply roller 14. This accumulated developer is transmitted in the thrust direction of the squeeze roller 20 and flows down from both ends of the roller. This flow in the thrust direction provides a stirring effect. On the other hand, the supply roller 14
The portion that has passed through the squeeze roller 20 sucks in new developer and supplies it to the developing roller 16, repeating the cycle. Thus, according to this embodiment, since the blade 18 and the like are not required, there is an advantage that the mechanism is further simplified.

FIG. 3 is a sectional view showing a third embodiment of the present invention. This embodiment is a modification of the first embodiment and the second embodiment in which the developer supply roller is constructed with a belt to increase the amount of developer supplied and to cope with higher speeds. be.

That is, a liquid developer 13 is stored inside the developer container 12, and a supply belt 30 is installed in the developer container 12 with a rack extending between a drive roller 31 and a driven roller 32. . The supply belt 30 is made of an elastic material having bubbles, and contains the developer 13 in the bubbles.
It is meant to be transported. Developing rollers 33 and 34 are disposed above the supply belt 30 so as to compress the supply belt 30 by a predetermined amount. Similarly, a squeeze roller 35 is supported downstream of the developing roller 34 so that it can rotate while squeezing the supply belt 30 by a predetermined amount.

The developing device of the third embodiment configured as described above operates as follows. When the supply belt 30 is rotated counterclockwise by the drive roller 31, the developer 13 that has entered the bubbles on the surface of the supply belt 30 is conveyed to the upper side of the drive roller 31 and reaches the position of the developing roller 33. do. Since the developing roller 33 crushes the supply belt 30, the developer 13 contained in the bubbles of the supply belt 30 is squeezed out and oozes out onto the surface. The developer 13 that oozed out to the surface is
Due to its surface tension, it is carried to the surface of the image carrier 11 while being placed on the surface of the developing roller 33 . Therefore, the latent image on the image carrier 11 is developed. A portion of the developer that has completed development is carried downstream by the surface tension of the image carrier 11 . The remaining particles fall onto the downstream peripheral surface of the developing roller 33 and the supply belt 30 due to gravity. The developer that has fallen onto the supply belt 30 travels along its surface or enters bubbles in the supply belt 30, and is carried to the developing roller 34 on the downstream side. Here, the same operation as the above-mentioned squeezing operation is performed, and the developer is transferred to the supply belt 30.
squeezed out onto the surface of And this developing roller 34
As a result, the developer 13 is supplied to the surface of the image carrier 11 and development is performed.

A portion of the developer after development is squeezed out from the surface of the image carrier 11 by the squeeze roller 35, and the remainder flows downstream of the developing roller 34, as described in the second embodiment. Then, it flows out along the thrust direction of the squeeze roller 35 and is collected in the developer storage section.

On the other hand, the developing rollers 33 and 34 and the squeeze roller 35
Since the rollers rotate in pressure contact with the supply belt 30, the cleaning work for each roller is performed. Since the developer 13 in the air bubbles is squeezed out by the squeeze roller 35 on the supply belt 3o, the squeeze roller 3
The portion of the supply belt 30 that has passed through the position 5 passes through the developer storage section again, so that new developer can be sucked in, transported, and supplied to the developing roller 33.

Thereafter, the above cycle is repeated, and developer supply and development are performed.

As described above, according to this embodiment, since the developer is supplied by the supply belt 30, the number of developing rollers can be increased. Therefore, even if the process speed becomes faster, there is an advantage that development can be carried out without any trouble.

It should be noted that the present invention is not limited to the various embodiments described above, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, the following effects are achieved. That is, a simple mechanism consisting of a combination of a supply roller or a supply belt and a developing roller can stably supply the liquid developer to the image carrier. Therefore, with a small and simple mechanism, developer can be well supplied to the image carrier, and high-quality development can be performed. Further, since the developing roller can be placed in a non-contact state with the image carrier, there is no risk of the surface of the image carrier being damaged by the surface of the developing roller, and the life of the image carrier can be extended.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of the first embodiment of the present invention, and FIG.
The figure is a sectional view showing the structure of a second embodiment of the present invention, and FIG. 3 is a sectional view showing the structure of a third embodiment of the invention. FIG. 4 and FIG. 5 are diagrams showing different conventional examples. 11... Image carrier, 12... Developer container, 13...
・Developer, 14... Supply roller, 15... Squeezing roller, 16... Developing roller, 17... Squeeze roller, 18... Blade, 20... Squeeze roller, 3
0... Supply belt, 31... Drive roller, 32...
・Followed roller, 33.34...Developing roller, 35...
・Squeeze roller. Applicant's agent Patent attorney Jun Tsuboi Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) In a wet development type electronic printer development device, there is a container for storing liquid developer, and the container rotates to transport and supply the developer to a predetermined position. A developing roller is provided so as to be supplied with the developer and to develop a latent image on an image carrier disposed in close proximity to the supply roller. A developing device for electronic printers using a wet development method. (2) The image forming apparatus according to claim 1, further comprising a squeeze roller disposed to remove excess developer from the image carrier after development and to be cleaned by contacting with the supply roller. A developing device for a wet-type electronic printer as described above. (3) The developing device for a wet-type electronic printer according to claim 1 or 2, characterized in that a supply belt is used in place of the supply roller that supplies the developer to the development roller.