JPS5825267B2 - Surplus developer removal device for electronic copying machines, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surplus developer removing device in an electronic copying machine or an electrostatic recording device.

For example, in an electronic copying machine or an electrostatic recording device in which an electrostatic latent image is formed on the surface of an image carrier consisting of a photoreceptor, and this latent image is converted into a toner image by a wet type developing device, after passing through the developing device, It is inevitable that the developer remains on the surface of the image carrier, and if this residual developer is left unattended, the quality of the completed copied image will deteriorate.

For this reason, conventionally, after a toner image is formed on the surface of an image carrier by a developing device, the surplus developer remaining on the surface of the image carrier is removed by a surplus developer removing device.

Various types of this type of removal device have been known, but in particular, a removal device using an air knife device is
It is widely used because it has the advantage of not disturbing the toner image on the surface of the image carrier and having a relatively simple structure.

However, the surplus developer removing device using an air knife device has a serious drawback in that the removal efficiency of the surplus developer is low and the developer removal action cannot be sufficiently performed.

The present invention aims to provide a surplus developer removing device that takes advantage of the advantages of the air knife device and has a higher developer removal efficiency than ever before.

Preferred embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, an electrostatic latent image is formed on the surface of an image carrier configured as a photoreceptor 1 by a latent image forming device (not shown), and the photoreceptor 1 on which the latent image is formed is indicated by the arrow It is transported in the A direction and brought to the wet developing device 2.

The developing device 2 in this example includes a case 3 and a case 3.
The developer head 4 is fixedly disposed within the developer head 4, and the developer head 4 is supplied with developer from a developer tank (not shown) through a supply conduit 5.

When the developer thus supplied flows out from the upper opening 6 of the developing head 4, this developer comes into contact with the photoreceptor 1, and at this time, the electrostatic latent image on the surface of the photoreceptor is converted into a toner image by the toner in the developer. be done.

5 It is unavoidable that the developer (mainly the solvent) remains on the surface of the photoreceptor after the development has been completed as described above, and as mentioned above, if this is left untreated, the quality of the completed copied image will deteriorate. That's right.

In order to eliminate this inconvenience, the residual developer is removed by a surplus developer removing device 7 according to the invention.

The surplus developer removing device 7 in this example includes an air knife device 8 and a blade 9 disposed between the device 8 and the developing device 20.

As is well known, the air knife device 8 includes a tube body 11 having an opening 10 at the top thereof, and two air knife members 12 fixed to the tube body and arranged in a substantially U-shape so as to cover the opening 10. The tips of the two air knife members 12 are positioned opposite to each other with a slit-shaped gap 13 in between.

Further, the tip of the air knife member 12 is located at a predetermined distance from the photoreceptor 1 without contacting the photoreceptor 1.

Air is force-fed into the tube body 11 from a blower 14, and the thus-forced air passes through the upper opening 10 of the tube body 11 and is blown out from the small gap 13 between the air knife members.

When the developed photoreceptor 1 is further conveyed in the direction of arrow A and reaches above the air knife device 8, the surface of the photoreceptor is blown with air ejected from the gap 13 between the air knife members.

This prevents the developer remaining on the photoconductor surface from being carried to the right in the figure beyond the air knife device 8, and as a result, the developer remains on the photoconductor surface to the left of the air knife device 8. A reservoir 15 is formed.

The tip of the blade 9 described above is arranged at a position where the liquid pool 15 is formed.

In this case, the tip of the blade 9 comes into contact with the liquid reservoir 15, but is spaced apart from the surface of the photoreceptor 1 to an extent that does not cause any risk of disturbing the toner image.

With the above configuration, the developer forming the liquid pool 15 on the surface of the photoreceptor is transferred to the blade 9, then flows downward along the blade, and is collected in the collection container 16 disposed below the blade 9. .

The thus collected developing solution is then sent through the discharge pipe 17 to a tank (not shown) or to the developing tank of the developing device.

In the conventional surplus developer removing device, the blade 9 was not provided, so even if an attempt was made to remove the surplus developer with an air knife device, a large amount of developer remained between the air knife device and the developing device, and this caused the problem. Therefore, the efficiency of removing excess developer of the air knife device was decreasing.

On the other hand, in the configuration shown in FIG. 1, focusing on the fact that a liquid puddle 15 is formed on the surface of the photoreceptor, the tip of the blade 9 is brought into contact with this liquid puddle 15, and the developer that tries to stay on the photoreceptor surface is removed. air knife device 8.
The developer removal efficiency of is significantly increased compared to the conventional method.

Moreover, since the tip of the blade 9 does not contact the surface of the photoreceptor, the toner image formed on the surface of the photoreceptor by development will not be disturbed by the blade.

Furthermore, the liquid reservoir 15 has a shape that protrudes downward at a certain height from the surface of the photoreceptor, and if the tip of the blade 9 is located within this height range, the blade can perform its function. Therefore, the attachment of the blade does not require strict accuracy, and the blade 9 can be attached easily.

The blade 9 in this example is fixed to a rotating shaft 19 with a screw 18 so that its position can be adjusted.
9 is adapted to be rotationally driven by a drive control device 20.

Then, by appropriately rotating the rotating shaft 19, the inclination angle B of the blade 9 with respect to the photoconductor 1 is adjusted, and the airflow flowing out from the air knife device 8 flows along the surface of the blade 90, and the developer attached to the blade 9 is is assisted by this air flow and can be made to flow down favorably.

In addition, the appropriate ejection air pressure of the air knife device 8 that can effectively remove the residual developer without disturbing the toner image on the surface of the photoreceptor varies depending on the properties of the toner, the characteristics of the photoreceptor, and the speed of the photoreceptor, and is not constant. Not yet.

In an electronic copying machine that transfers a toner image on the surface of a photoreceptor onto a transfer sheet, the above-mentioned appropriate ejection air pressure usually changes depending on the properties of the transfer sheet.

Therefore, in the configuration shown in FIG.
The air discharge amount of the blower 14 can be adjusted by taking the above-mentioned factors into account, and the air discharge amount of the blower and therefore the pressure of the air flowing out from the gap 13 between the air knife members can be adjusted to an appropriate value. can do.

In this case, above the air knife device 8, a non-image area of the photoreceptor (i.e., a non-developing area between a toner image area formed in one developing operation and a toner image area formed in the next developing operation) is provided. It is also advantageous to increase the pressure of the air flow by the air knife device only when ) is reached.

In this way, residual developer can be removed more effectively, and since there is no toner image in the non-image area, there is no risk of disturbing the toner image even if the air pressure increases.

Furthermore, the appropriate ejection air pressure of the air knife device described above can also be adjusted by rotating the air knife member 12 in the direction shown by arrow C to vary the angle at which the ejected air hits the photoreceptor.

As described above, when the blowout air pressure of the air knife device 8 is changed, the proper inclination angle B of the blade 9 also changes accordingly, so the air pressure control device 21 and the drive control device 20 are configured to work together, so that the blowout air pressure can be changed. In this case, the blade 9 is automatically tilted to adjust the blade inclination angle B to suit the ejection air pressure.
It would be particularly advantageous if .

Furthermore, the blade 9 is driven by a driving device such as a plunger type solenoid or a rotary solenoid (not shown).
The blade tip is configured to be able to selectively move between the position shown in FIG. It is also advantageous to bring the tip of the blade 9 into pressure contact with the surface of the photoreceptor 10.

In this way, the blade 9 acts to scrape off the residual developer on the surface of the photoreceptor, so that the developer can be effectively removed.

Moreover, since the blade 9 contacts only the non-image area of the photoreceptor, there is no risk of disturbing the toner image.

The blade 9 described above is desirably made of a material with excellent wettability to which excess developer easily adheres, and especially when the blade is configured to be able to come into contact with the surface of the photoreceptor, the blade is It is advantageous to construct the blade from a flexible material that does not damage the blade.

In addition, 22 in FIG. 1 is configured such that the air knife device 8 blows a high-pressure air flow only onto the non-image area of the photoreceptor, and the blade 9 also slightly contacts the non-image area of the photoreceptor. This figure shows a timing control device that switches the air pressure and the movement of the blades.

Although the above-described embodiment is a specific example in which the present invention is applied to an electronic copying machine that produces a monochromatic copy image, the present invention can also be advantageously applied to a color copying machine that produces a copy image of two or more colors.

FIGS. 2 and 3 show a specific example in which the present invention is applied to a color copying machine.

The configuration shown in FIG. 1 was provided with only one developing device, but in color copying machines, toner images are obtained using toner of multiple colors.
A plurality of developing devices are provided depending on the number of toner colors.

In the example shown in FIG. 2, three developing devices 2, 2a, and 2b are arranged side by side, and each of these developing devices accommodates yellow toner, magenta toner, and cyan toner.

The cases 3.3a and 3b of each developing device are supported so as to be vertically movable between an operating position and a non-operating position.

As is well known, a latent image corresponding to each color of the original image is formed three times on the photoreceptor 1 from one original (not shown), and each developing device converts the latent image into a toner image each time.

That is, the first latent image is a yellow toner image formed by the first developing device 2, the second latent image is formed a magenta toner image by the second developing device 2a, and the third latent image is formed by the second developing device 2a. A cyan toner image is formed by the developing device 2b of No. 3.

These toner images are superimposed and transferred to a transfer sheet (not shown), thereby forming a color image on the transfer sheet.

As mentioned above, in this type of color copying machine, for the purpose of obtaining one color image, the photoreceptor 1 passes through the developing devices 2.2a and 2b three times, and each time the photoreceptor 1 passes through the case 3 of one developing device.
, 3a or 3b are held in the raised operating position, and the latent image is converted into a toner image by the developing device thus switched to the operating position.

After completing this developing operation, the case of the developing device is lowered from the operating position to the non-operating position (in Fig. 2, the case 3 of the first developing device is in the operating position, and the case 3 of the other developing device
a, 3b show the state in the inoperative position).

As can be seen from the above description, during a series of operations to obtain one color image, the photoreceptor 1 comes into contact with toners of different colors three times.

Therefore, during each of the three developing operations, unless the developer remaining on the photoreceptor is removed, the developer of each color will mix, making it impossible to obtain a high-quality color image.

Further, in a color copying machine as shown in FIG. 2, when the case 3, 3a or 3b of the developing device is lowered to its inoperative position, a relatively large amount of developer remains on the surface of the photoreceptor due to surface tension.

Therefore, in this type of color copying machine, it is necessary to remove the residual developer in the developing machine particularly efficiently, and the device shown in FIG. 7 is provided, and excess developer on the surface of the photoreceptor is effectively removed for each development operation.

Therefore, high quality color images can be obtained.

In FIG. 2, 23 is a tank containing the developer collected by the blade 9, and 24 is a developing device 2.2a, 2b.
25 is a developing tank for the first developing device 2, and the developer in this developing tank 25 is pumped. 26 supplies the case 3 through the conduit 5.

Further, the pump 26 is driven by a motor 27, and this motor 27 is controlled by a liquid supply control device attached to the developer case drive device 24.

Furthermore, a developing case drive device 24 including this liquid supply control device
is controlled by a timing control device 22 also shown in FIG.

Further, the second and third developing devices 2a and 2b are also provided with a developing tank, a pump, and a motor similar to those of the first developing device.

The other configurations of the second and third developing devices 2 a t 2 b are completely the same as the first developing device 2 .

FIG. 3 also shows a developing device and a surplus developer removing device for a color copying machine, and the difference between this embodiment and the embodiment shown in FIG. two surplus liquid removal devices 7, 7a.

7b is provided, and each air knife device 8.8 is provided accordingly.
A device 28 for distributing and supplying air to each tube body 11.11a>11b of a and 8b is provided, and a blade 9.9
The developer collected by a, 9b is transferred to each developing device 2.
> 2 a > 2 b developing tank 25.25a
, 25b.

The configuration according to the present invention described above can be particularly advantageously applied to a copying machine that forms a copy image on wide-width copy paper, but it goes without saying that it can also be advantageously applied to a copying machine that uses narrow-width copy paper.

As described above, according to the present invention, the conventional drawbacks can be eliminated with a simple configuration.

[Brief explanation of drawings]

1. FIG. 1 is an explanatory diagram showing an embodiment of the invention applied to an electronic copying machine, and FIGS. 2 and 3 are explanatory diagrams showing other embodiments of the invention. 1... Image carrier, 2, 2a, 2b...
・Developing device, 7, 7a, 7b... Surplus developer removing device, 8゜' 8 a, F3 b...
・Air knife device, 9.9 a t 9 b...
·blade.

Claims (1)

[Claims] 1. After forming a toner image on the surface of an image carrier using a wet developing device, excess developer remaining on the surface of the image carrier is removed.
In a device for removing surplus developer in an electronic copying machine or the like, in which excess developer is removed by an air knife device, a blade is provided between the developer device and the air knife device, and the tip of the blade is disposed close to the surface of the image carrier. The surplus developer removing device. 2. The surplus developer removing device according to claim 1, wherein the blade is supported so as to be able to approach and separate from the image carrier, and is configured to bring the blade into contact with a non-image area on the surface of the image carrier. 3. The surplus developer removing device according to claim 1 or 2, which is configured to be able to adjust the outflow air pressure of the air knife device.