JPS6259312B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image processing apparatus, and more particularly, to an image processing apparatus, which forms an electrostatic latent image on an image carrier, develops the image, transfers the developed image, and cleans the image carrier after the transfer. The present invention relates to an improvement of an image processing apparatus that is subjected to the above-mentioned process cycle again.

An electrophotographic copying machine is a typical device that uses the above process cycle to obtain a desired image. An electrophotographic copying machine generally employs a drum-shaped or belt-shaped photoreceptor, rotates or circulates the photoreceptor, and forms, develops, and transfers a latent image at each fixed position along the movement path. It's becoming like that. After the transfer, the developer remaining on the surface of the photoreceptor is removed at a cleaning position, and the photoreceptor whose surface has been cleaned is moved again to obtain a desired transferred image.

In an apparatus in which an electrostatic latent image is developed using dry development in the development process, that is, a dry powder developer is used, the cleaning is carried out by sweeping with a fur brush that rotates in contact with the photoreceptor. At present, it is common practice to wipe the photoreceptor with a blade made of an elastic material such as rubber or plastic that is pressed against the photoreceptor.

Compared to fur brush cleaning, it is the most aggressive cleaning method as it requires a smaller device and is in complete contact with the surface of the photoreceptor. Recently, cleaning with a blade has been frequently performed because of the many advantages such as the ability to relatively easily realize a system in which toner is transported into a developing device using a transport means such as the above and reused.

However, in the case of cleaning with a blade, the coefficient of friction between the photoreceptor and the cleaning blade changes significantly depending on the surface material of the photoreceptor and the material used for the cleaning blade. Therefore, depending on the material of the surface of the photoreceptor and the material of the blade, cleaning scratches on the surface of the photoreceptor and wear of the blade edge may occur, shortening the life of the cleaning blade.

In addition, as high-speed copying machines become faster, the moving speed of the photoreceptor surface increases, so the frictional force between the photoreceptor and the cleaning blade cannot be ignored, and the cleaning blade may cause the blade edge to sink into or separate from the photoreceptor drum. Not only does the entire cleaning device vibrate and the entire cleaning device makes abnormal noises, but repeated use may cause wear of the blade edge or damage to the rubber elasticity of the blade edge, resulting in poor cleaning that adversely affects image formation.
This also causes cleaning scratches on the surface of the photoreceptor.

Additionally, since there is friction between the blade and the surface of the photoreceptor, this tends to cause the developer to stick to the surface of the photoreceptor, but this tendency is particularly noticeable in high-speed copying machines such as those mentioned above. Accidents occur in which the developer adheres to the surface of the photoreceptor in stripes that are difficult to remove and adversely affect image formation. Therefore, in order to solve this inconvenience, we added tetrafluoroethylene, polyethylene,
Lubrication can be achieved by mixing dry powder lubricants such as stearate metal salts and Kuruk (external addition), or by mixing the above materials into the developer base material during developer production (internal addition). and/or use tetrafluoroethylene in the cleaning blade.
Attempts have been made to reduce the coefficient of friction between the cleaning member and the photoreceptor by selecting a material with good lubricity such as polyethylene or by coating the fur brush with tetrafluoroethylene.

However, when the above dry lubricant powder is externally added to the developer, although satisfactory lubricity can be obtained, there are problems in the formation of developed images. For example, the charging characteristics of powder lubricants (for example, tetrafluoroethylene powder is negatively charged in the developer of negatively charged toner)
There are problems such as a decrease in the density of the developed image due to the fact that the toner has an effect on the charging of the toner, and the developer itself becomes slippery. In addition, such powdered lubricants tend to scatter and cause contamination of machines.

Furthermore, even if dry lubricant powder is applied directly to the photoreceptor instead of being mixed into the developer, the powder lubricant will be mixed into the developer when the developer is reused after cleaning. , the same problem as above arises.

Furthermore, when a dry lubricant was added internally to the developer, the lubricity was much lower than when it was added externally, and no satisfactory results could be obtained. Further, when a blade made of a material with good lubricity such as Teflon or polyethylene is used, although the lubricant is good, the edge portion is easily worn and damaged, and the cleaning performance is unstable.

Even if the fur brush is coated with any of the above materials, the coating is easily torn and the cleaning performance deteriorates in a short period of time.

The main object of the present invention is to provide a method and apparatus capable of solving the disadvantages of the various methods and apparatuses described above, and to provide an image bearing member and a cleaning blade in contact therewith without adversely affecting image forming performance. An object of the present invention is to provide a method and a device that can improve the lubricity between the two. Thus, the present invention is characterized in that it includes an elastic roller that applies a small amount of silicone oil to the surface of the image carrier after cleaning the blade and before the electrostatic latent image is formed. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of an embodiment in which the present invention is applied to an electrophotographic copying apparatus. Reference numeral 1 denotes a photosensitive drum, which has a photosensitive member 2 formed by sequentially layering a conductive layer C, a photoconductive layer P, and a transparent insulating layer I on its circumferential surface. Photosensitive drum 1
is adapted to be rotated at a constant speed in the direction of the arrow by a drive device (not shown).

3 is a corona discharger which uniformly charges the surface of the photoreceptor, positively when the photoconductive layer P is an N-type semiconductor, and negatively when it is a P-type semiconductor.

4 is an in-mirror lens, which is illuminated by a lamp 5 and sent in the direction of the arrow in synchronization with the rotation of the drum 1. The optical image of the original 6 is projected and formed on the photoreceptor 2 at the exposure position in cooperation with the mirror 7.

8 is a corona discharger, which has an aperture through which the light beam from the lens 4 passes, and performs AC corona discharge or corona discharge of opposite polarity to the discharger 3 at the same time as image exposure;
Charges on the surface of the photoreceptor caused by the discharger 3 are removed.
As a result, an electrostatic latent image corresponding to the optical image of the original 6 is formed on the photoreceptor 2.

Reference numeral 9 denotes a full-surface exposure lamp that projects light onto the entire surface of the photoreceptor 2 that has passed through the exposure position. This forms an electrostatic latent image with high contrast.

10 is a developing device. The developing device 10 includes a container 12 that stores a dry developing powder, that is, a powder 11 made of a mixture of dry toner and dry carrier particles (magnetic material in this case), and a rotating device that stirs the powder 11 within the container 12. Screw 13 and fixed magnetic bar 14
and a rotating sleeve 1 loosely fitted to this magnetic bar.
5, and the latent image formed on the photoreceptor 2 is developed with a magnetic brush.

A timing roller 15 sends out the transfer paper conveyed from a paper feed cassette (not shown) under the guidance of a guide plate 16 in synchronization with the rotation of the drum 1.
It is adapted to be brought into contact with the developed toner image on the surface of the photoreceptor 2. At the transfer position, one end of the transfer paper is wrapped around pulleys 17 to 21, and the separation belt 2 is transferred by contacting the drum 1.
2 and the drum 1. Therefore, the transfer paper that has passed the transfer position is separated from the surface of the drum 1 by the action of the separation belt 22. The separated transfer paper carrying the toner image is sent to a fixing device (not shown), and then to a collection tray.

In addition, 23 is a corona discharger, and on the back of the transfer paper,
Gives a charge of opposite polarity to the toner transferred to the surface,
This improves transfer efficiency.

24 is a blade made of an elastic material such as rubber or plastic. Although this blade 24 has a rectangular parallelepiped plate shape in the embodiments shown in FIG. 1 and below,
In this way, the blade 24 has at least a ridge-like edge 24' and a surface 24'' for blocking the wiped toner.The blade 24 uses the edge 24' and its vicinity to cover the surface of the photoreceptor 2 of the drum 1. In this way, the blade 24 wipes off the toner remaining on the surface of the photoreceptor 2 after transfer.
The toner parked at the front of the blade is sent back into the container 12 of the developing device 10 by a known conveying means equipped with a conveying screw or the like disposed along the front surface 24'' of the blade, and is reused. It is.

Now, after the residual toner after transfer is removed by the blade 24 and before it is uniformly charged by the corona charger 3 for forming an electrostatic latent image, an extremely thin film of liquid lubricant is formed on the surface of the photoreceptor 2. formed, but the first
In the illustrated embodiment, a roller 25 soaked with liquid lubricant is brought into contact with the surface of the photoreceptor 2 for this purpose. That is, 25 is a silicone rubber roller impregnated with silicone oil to a substantially saturated state. This roller 25 contacts the drum 1 with such pressure that the infiltrated silicone oil oozes out and is applied to the surface of the photoreceptor 2 in an appropriate amount, and the shaft of the roller 25 is forcibly rotated by the driving force of a motor or the like. It is rotatably supported by a bearing (not shown). Further, at this time, it is also possible to forcibly rotate the drum 1 so that it rotates in the opposite direction to the drum 1 at the contact position with the photoreceptor 2.

The material of the silicone rubber roller 25 is as follows:
RTV (room temperature vulcanization type) silicone rubber is generally suitable because it easily exudes the oil it contains, and its hardness is generally about 20 to 60 degrees. If the hardness is less than 20 degrees, it will be difficult to shape it as a roller, and even if it is shaped, the surface will be rough, making it difficult to apply silicone oil uniformly.If the hardness is more than 60 degrees, it will be difficult to apply silicone oil. Since it is difficult to contain and deform when it comes into contact with the photoreceptor 2, oil is also difficult to ooze out, making it difficult to apply an appropriate amount of silicone oil.

Of course, these are not absolute limits, and the photoreceptor 2
The conditions should be selected appropriately depending on the frictional characteristics between the photoreceptor 2 and the blade 24, and it is not necessary to make very beautiful copies, or the friction coefficient between the photoreceptor 2 and the blade 24 is extremely small. has a hardness of 20
It can be below 60 degrees or above 60 degrees.

Similarly, depending on the purpose, HC (heat vulcanization type) silicone rubber, which is generally resistant to leaching out the oil it contains, can also be used.

Further, as the roller 25, a foamed rubber such as silicone rubber, urethane rubber, or nitrile rubber impregnated with silicone oil to a substantially saturated state can also be used. Various coating amounts can be selected by changing the porosity and/or pore size of the foam rubber.

Silicone oil was selected as the lubricant in the examples because silicone oil has a property of having very weak adhesion to foreign substances, in other words, it has good mold releasability, and it is related to such characteristics. This is because it has good lubricity. Viscosity 300CS for silicone oil
It is preferable to use one with a relatively low viscosity of (centistokes) or less. Viscosity is greater than 300CS,
In particular, when the concentration exceeds 1000 CS, it is not only difficult to handle as a liquid itself, but also difficult to infiltrate into rollers, etc., resulting in problems such as poor adhesion of toner to the latent image during development.

For example, in Figure 1, if the diameter is 160mm and the width is 350mm, it will be 26r.pm.
When the surface layer I of the photosensitive drum 1 that is rotated by is formed of a photocurable acrylic urethane layer and a urethane rubber blade is used as the cleaning blade 24 (pressed against the drum 1 with a pressure of 0.7 kg/cm ² ), silicone oil swells. A4 paper if there is no roller 25
5000 copies (A430 copies/1 rotation of the drum)
A sliding noise due to the vibration of the cleaning blade 24 and black streaks caused by toner sticking were generated on the drum 1 due to poor cleaning. Next, as the oil swelling roller 25, KE-12 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. is vulcanized, and then soaked in silicone oil at 13℃ (KE96 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd., viscosity 20CS) for 3 days to swell. After that, when a roll shape with an outer diameter of φ30 and a wall thickness of 8 mm was shaped and polished and brought into contact with the photosensitive drum 11 and rotated under the same conditions as above,
Even when copying 100,000 sheets of A4 paper, both cleaning properties and image quality were good.

In addition, silicone oil infiltrated silicone rubber roller 25
can be made by immersing the vulcanized product in silicone oil as described above, or by mixing 10 to 50% by weight of silicone oil in an unvulcanized silicone rubber compound and then vulcanizing and shaping the mixture. You can also do it. The mixing amount of the silicone oil is appropriately selected depending on the saturation ability of the silicone rubber.

Incidentally, the silicone oil in the rubber roller 25 of the embodiment shown in FIG. 1 will gradually decrease with long-term use, but it is sufficient to replace it with a new roller every certain period of time. Therefore, FIG. 2 shows an improved example of the embodiment shown in FIG. 1.

That is, a hollow pipe 26 having a large number of small holes 26' was used as the core body 26 of the silicone rubber roller 25 impregnated with silicone oil similar to that described above with reference to FIG. 1 to a substantially saturated state. Both ends of the pipe 26a are closed, but the pipe 26a is filled with the same silicone oil that is infiltrating the rubber roller 25. The silicone oil in this pipe 26 is
The oil gradually diffuses into the silicone rubber through the silicone rubber roller 6', and a suitable amount of oil always oozes out onto the surface of the silicone rubber roller 25. In this way, the frequency of replacing rollers 25 is significantly reduced.

In the embodiment shown in FIGS. 1 and 2, a solenoid or the like may be used to bring the elastic roller into contact with the surface of the drum 1 intermittently and periodically.

Furthermore, as shown in the above embodiments, in the present invention, the liquid lubricant film forming means is disposed between the cleaning means and the electrostatic latent image forming means, and after cleaning, and after the latent image formation. A film of silicone oil is formed on the surface of the previous image carrier. This is because it is preferable to form a liquid lubricant film at this position from the viewpoint of image formation and the life span of the film forming means. That is, if the film forming means is placed between the transfer position and the cleaning position, the lubricant application member will be rapidly and significantly contaminated with developer, resulting in a decrease in lubricant application performance and insufficient cleaning, resulting in image bearing. It may cause damage to the image forming apparatus or a reduction in image forming performance, and if it is placed in the latent image forming means or between the latent image forming means and the developing means, it may damage the latent image or otherwise have an unfavorable effect on the latent image. So it's not good. Similarly, it is also undesirable to dispose a liquid lubricant film forming means between the developing means and the transfer means, since this will have an undesirable effect on the development process, such as damaging the developed image.

Furthermore, if the amount of liquid lubricant that forms a film on the surface of the image carrier is too small, the lubricity will be reduced, resulting in the same problem as when no lubricant is used, and if it is too large, the transfer efficiency will be reduced. This causes problems such as the transferred image becoming thinner. According to experiments, under the conditions described above with reference to FIG. 1, forming a film of silicone oil of 3 x 10 ^-5 to 1 x 1 ^-3 ₃ cc per revolution of the drum 1 did not cause the above-mentioned disadvantages. First, good cleaning performance and image forming performance were obtained.

Further, although the present invention is applied to an electrophotographic copying machine in the embodiment, the present invention is not limited thereto, and the present invention is not limited thereto. The electrostatic latent image is formed on the photoreceptor according to the above-mentioned output, and then the photoreceptor is dry-developed, and then the photoreceptor is cleaned and reused. The present invention can be used in a method and apparatus having a cycle of forming a latent image, developing it, transferring it, and cleaning it.

The present invention simply prevents damage to the surface of an image carrier;
In addition to the effect of preventing wear of the cleaning means, since the elastic roller is brought into pressure contact with the image carrier, a rubbing effect of the roller on the surface of the image carrier, that is, a cleaning effect can also be obtained. In addition, by infiltrating the inside with silicone oil and using an elastic roller that presses against the image carrier, the infiltrated silicone oil oozes out and is applied to the surface of the image carrier in an appropriate amount, forming a thin film of silicone oil. This thin film of silicone oil provides good surface insulation and can prevent so-called image blurring. Therefore, as is clear from the above description, according to the present invention, it is possible to obtain and maintain good cleaning performance without adversely affecting image formation, and it is possible to prevent poor cleaning performance. This makes it possible to prevent the deterioration of the image or the deterioration of the image bearing member caused by this, and it becomes possible to obtain beautiful images that last for a long period of time.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams of embodiments of the present invention, respectively. 1 is a photosensitive drum, 2 is a photosensitive member, 3 is a corona discharger, 4 is a lens, 6 is a document, 8 is a corona discharger,
9 is a full-surface exposure lamp, 10 is a dry developing device, 15 is a timing roller for transfer feeding, 23 is a corona discharger for transfer, 24 is a cleaning blade, and 25 is a liquid lubricant soaking roller.

Claims (1)

[Scope of Claims] 1. An image bearing member, a latent image forming means for forming a latent image on the image bearing member, a developing means for developing the latent image formed by the latent image forming means, and the developing member. a transfer means for transferring an image developed by the means to a transfer material; a cleaning blade for removing developer remaining on the image carrier from the image carrier after the image is transferred by the transfer means; and a cleaning blade for removing the developer remaining on the image carrier from the image carrier; an elastic roller that is provided downstream of the cleaning blade and before the formation of the latent image with respect to the direction of movement of the body, is infiltrated with silicone oil, is in pressure contact with the image carrier, and is forcibly rotated; An image processing device characterized by: