JPH03152585A - Wet copying machine - Google Patents

Abstract

PURPOSE:To prevent toner from sticking on a photosensitive body and to reduce torque by using developer constituted by kneading the toner with 1ow volatile carrier liquid. CONSTITUTION:As for the developer, the low volatile carrier liquid is used as the carrier liquid, and it is desirable to use a substance having siloxane structure, for instance, polymethyl phenylsiloxane as the low volatile carrier liquid. Namely, in the case of starting a copying action after the machine is left unused for a long time, the stuck toner on the photosensitive drum 1 is cleaned out just by making the leading edge of a virtual image pass a cleaning device once when this developer is used. Therefore, cleaning is perfectly performed by making the part of the stuck toner which occurs by the puddle of the developer caused by a 1st developing roller 13 on the photosensitive drum 1 pass the cleaning blade 26. Thus, the toner is prevented from sticking on the photosensitive body 1 and the cleaning blade 26 is used in a state where it is inclined to the photosensitive body 1 on the upstream side thereof, then the torque of a main body is reduced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a wet type copying machine using a liquid developer.

[Conventional technology]

Conventionally, a carrier liquid for a developer used in a wet type copying machine (wet type electrophotographic copying machine) is a petroleum-based aliphatic hydrocarbon solvent, such as Isopar (I 5 opar ) 2% GsH,L.
, N, M (manufactured by Esso Standard Oil Co., Ltd.),
Examples include Shellzol 71 and Tsurpetz 150 (manufactured by Shell Oil Company). In addition, other carrier liquids include cyclohexane, n-hexane, n-hebutane, n-nonane,
Examples include n-octane, isooctane, isododecane, and ligroin.

In order to obtain a developer, a colorant, a dispersion resin, and other minor additives are kneaded together with the carrier liquid using a ball mill, a kedimir, etc. to form a reduced toner, and this is mixed into an appropriate amount of the carrier liquid. It should be distributed to

When a copying operation is performed using the developer obtained in this way, toner particles in the electrostatic latent image remaining on the photoreceptor without being transferred from the photoreceptor to the transfer paper are removed from the vicinity of the photoreceptor. is removed from the photoreceptor by a cleaning unit located at. In this cleaning unit, a form roller to which developer sucked up from a developer tank is supplied slides on a rotating photoreceptor and rotates, thereby removing remaining developer from the photoreceptor. The photoreceptor is then completely removed by the cleaning blade of the cleaning unit. The cleaning operation is performed by repeating such steps, that is, by rotating the photoreceptor many times.

[Problem to be solved by the invention]

By the way, when copying is performed using the developer obtained in this way, a serious problem in wet type copying machines is that toner sticks due to the volatile nature of the petroleum-based aliphatic hydrocarbon solvent. there were. Among these, in order to prevent toner from sticking on the photosensitive drum, which has a particularly bad effect on images, a counter-type cleaning blade is conventionally used in a cleaning device for a wet-type copying machine. Although this counter type cleaning blade has excellent cleaning performance, it has the disadvantage that the torque of the copying machine body becomes extremely large due to friction with the photoreceptor. Furthermore, if the toner is badly stuck on the photoreceptor, it is necessary to provide a pre-cleaning time before starting the copying operation.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a wet-type copying machine that does not cause toner sticking and can significantly reduce torque.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a photoreceptor on which a latent image of an original image is formed by exposure, a developer formed by kneading a toner and a low-volatility carrier liquid, and a photoreceptor on which a latent image of a document image is formed. A developing device that develops the formed latent image with the developer, and a cleaning unit that includes a foam roller made of a foam and a cleaning blade made of an elastic material for removing residual toner on the photoreceptor. , the cleaning blade is tilted upstream of the photoreceptor and comes into contact with the photoreceptor.

[Effect]

With the above means, toner adhesion on the photoreceptor is prevented, the cleaning blade can be used with the cleaning blade tilted upstream of the photoreceptor, and the torque of the main body can be significantly reduced.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
The figure is an explanatory diagram showing a schematic configuration of a wet-type copying machine according to the present invention.

In FIG. 1, during copying, the photosensitive drum l is rotationally driven by a drive device in a fixed direction in the direction of the arrow in the figure, and after being uniformly charged by a charger 2, a document image is projected by an exposure device 3. A latent image is formed. Then, the portion of the photosensitive drum 1 outside the image area is neutralized by the eraser 4.

The latent image on the photosensitive drum 1 is developed by a developing device 5, and transferred by a transfer charger 8 onto a transfer paper 7 fed from a paper feeding device (not shown) via a conveyance roller 6 as shown by a broken line.

The transfer paper 7 is separated from the photosensitive drum 1 by a separation roller 9, conveyed by a conveyor belt 10, and after the toner is fixed by a fixing device (not shown), it is discharged to the outside. After 1 g of transfer paper 7, residual toner is removed from the photosensitive drum 1 by a cleaning unit 11.
The residual potential is removed by a static eliminator 12 consisting of a static eliminator lamp or a static eliminator charger in preparation for the next copy.

In the developing device 5, a first developing roller 1 is disposed inside the developing container.
3 and a second developing roller 14 are respectively arranged, and a reverse roller 15 is further arranged, and the first developing roller 13 and the second developing roller 14 are held at a small distance from the surface of the photoreceptor drum l. This feeling is adjusted to 0.1 mm, and the first color image roller 13 and the second developing roller 14 are driven by a driving device to rotate in the direction opposite to the photoreceptor drum 1 as shown by the arrow at a peripheral speed faster than the photoreceptor drum 1. be done.

The souffle bars 16 and 17 fixed inside the developer container are
The rollers are in contact with the first developing roller 13 and the second developing roller 14, respectively, to constantly clean the toner on the developing rollers.

The developer in the developer tank 19 is supplied by the pump 18 from the developer supply nozzle 21 via the supply pipe 20.
The supplied developer is uniformly conveyed to the surface of the photoreceptor drum 1 by the rotation of the first developing roller 13, the second developing roller 14, and the souffle bar 16. 13 and second developing roller 1
It flows in the gap between 4 and 1. After developing the latent image on the photoreceptor drum 1.1:, the developer recovery hole 22 and the developer recovery port are opened.
The liquid is collected in the developer tank 19 after passing through the tube 23 and is reused.

The reverse roller 15 is moved by the photosensitive drum 1 by a driving device.
The developer is rotated in the opposite direction to scrape off the excess developer on the photoreceptor drum l-, and the developer on the upper surface of the photoreceptor drum l is scraped off by the souffle bar 24.

The cleaning unit 9 has a sponge-like foam roller 25 that comes into pressure contact with the photoreceptor drum 1 and a cleaning blade 26 made of an elastic material such as rubber. , the developer is supplied from the developer tank 19 into the cleaning unit 9 after passing through the supply pipe for two days. The supplied developer is transferred to a diffusion plate 29 provided below the liquid supply nozzle 27.
This spreads the entire width of the form roller 25. Then, the cleaned residual toner and paper dust are squeezed out by a squeezing roller 30 together with the liquid, and returned to the developing tank 19 through a collection pipe 32 from a hole 31 at the bottom of the cleaning unit 9 .

As the number of times of development increases, the toner concentration in the liquid developer decreases, so this is constantly detected, and if the concentration drops below a predetermined level, toner is replenished into the liquid developer and the toner tta change is constantly maintained at a predetermined level. It is designed to stay within range.

FIG. 2 is an explanatory diagram showing details of the cleaning unit 9.

In this figure, 33 and 34 are solenoids, and the solenoid 33 has its operating shaft 35 connected to a rotating lever 36.
The cleaning blade 26 is attached to the rotating lever 36, and by operating the solenoid 33, the cleaning blade 26 is brought into contact with or separated from the surface of the photoreceptor drum 1. This abutting operation is indicated by a white arrow. This cleaning blade 26 is of a so-called trailing type in which it is brought into contact with the surface of the photoreceptor drum 1 while being tilted upstream of the photoreceptor drum 1 . In addition, the solenoid 34 has its operating shaft 3
7, the rotating lever 38 interlocks with the operating shaft 37.
．． The diffusion plate 2 is fixedly attached to the rotary lever 39 via 39.
9 is moved toward and away from the form roller 25. This separation motion is indicated by black arrows. 40 is a soufflé bar,
This souffle bar 40 comes into contact with the squeezing roller 25 and constantly cleans the toner on the squeezing roller 25.

In the above embodiment, the developer pool A accumulated between the photoreceptor drum 1 and the cleaning plate 26 during the copying operation is removed from the cleaning blade 26 by the solenoid 3 after the copying operation is completed.
Although it remains on the photoreceptor drum 1 even after being released by step 3,
In the case of this example, polymethylphenylsiloxane is used as the carrier liquid, and even when the copying operation starts after being left for a long period of time, this developer can be The tip of the photoconductor drum l passes through the cleaning device once.
The stuck toner on top is cleaned. In other words, a part of the adhesive 1, which is caused by a developer pool due to the first developer 1 cola 13 on the photoreceptor drum 1, is attached to the cleaning blade 1.
6, the cleaning has been completed completely, and in the pre-cleaning operation, exposure is started and a copying operation is performed before the photosensitive drum I completes one revolution. Therefore, the leading edge of the virtual image is set at the 101st rotation of the photosensitive drum during the pre-cleaning operation.

The developer uses a low-volatility carrier liquid as its carrier liquid. A substance having a siloxane structure, such as polymethylphenylsiloxane, is used as the low-volatility carrier liquid.

Example 1 Polymethylphenylsiloxane was used as the carrier liquid.

Example 2 A mixed solution of 95% by volume of I 5opar H and 5% by volume of polymethylphenylsiloxane was used as a carrier liquid.

Example 3 A mixed solution of 90% by volume of I 5opar H and 10% by volume of polymethylphenylsiloxane was used as a carrier liquid.

Example 4 A mixed solution of 85% by volume of l5oparH and 15% by volume of polymethylphenylsiloxane was used as a carrier liquid.

Example 5 As a carrier liquid, a mixed solution containing 50% by volume of I5opar)I and 50% by volume of polymethylphenylsiloxane was used.

Comparative example 1 I5opar G was used as a carrier liquid.

Comparative example 2 T5oparH was used as a carrier liquid.

Comparative example 3 I5opar L was used as a carrier liquid.

On each side of the above, add Ricoh CT-50 to each carrier liquid.
After running 10,000 sheets under each condition using a developer prepared by diluting 85 toner to 100g/l',
FIG. 3 shows the results of comparing the state of toner adhesion on the photosensitive drum after leaving it for one day. In addition, in Figure 3, ○
: Toner adhesion is not observed at all, Δ: Toner adhesion is slightly observed but can be easily removed, ×: Toner adhesion is observed and pre-cleaning operation is required.

As is clear from FIG. 3, in the comparative example, the toner adhesion state was poor and poor, but in the examples, all the toner adhesion states were ○, and no toner adhesion was observed. Therefore, there is no need for a pre-cleaning operation, and the cleaning blade can be brought into contact in a trailing manner. With this combination, the power of the solenoid 33 for bringing the cleaning blade into contact with the photoreceptor drum can be reduced, and the cost can be reduced compared to the conventional method.

In this conventional wet-type copying machine, a small amount of developer remains on the photoreceptor drum, and if it is left for a long time, the solvent evaporates and the toner sticks. To clean it, the cleaning blade has to dig in a considerable amount. Since it was necessary, we had no choice but to use the counter method, and the torque was also large. However, by adopting the trailing method, the main body torque can be significantly reduced compared to the conventional counter one-type cleaning blade.

〔Effect of the invention〕

As described above, according to the present invention, there is no toner sticking and torque can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a schematic configuration of a wet type copying machine, FIG. 2 is an explanatory diagram showing details of a cleaning device, and FIG. 3 is a diagram showing measurement results. 1......Photoreceptor drum, 5......
...Development device, 8...Transfer device π, 11.
...Cleaning unit, 2G...
...Cleaning blade. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A photoreceptor on which a latent image of a document image is formed by exposure, a developer obtained by kneading toner and a low-volatility carrier liquid, and a developer that forms a latent image of an original image on the photoreceptor; a cleaning unit having a foam roller made of a foam material and a cleaning blade made of an elastic material for removing residual toner on the photoreceptor; A wet-type copying machine characterized by being tilted upstream and in contact with a photoreceptor. (2) The wet type copying machine according to claim (1), wherein a substance having a siloxane structure is used as the low-volatility carrier liquid.