CN1770041B - Cleaning device, process cartridge, and image forming device - Google Patents

Abstract

In the cleaning device, the process cartridge, and the image forming apparatus, a cleaning structure with low linear pressure and high surface pressure is obtained by specifying the material and shape of the cleaning blade and the supporting structure. A tip edge line portion of an elastic cleaning blade 38 supported by a supporting member 37, which is a so-called sheet holder, is pressed against a roller-shaped and belt-shaped image carrier 10 to remove toner remaining on the image carrier after image transfer. In the cleaning device (16), the angle (theta) of the cleaning blade forming the front end edge line part (36) is formed into an obtuse angle, and is greater than or equal to 2.0g/mm²The front end edge line part is pressed on the image carrier by the surface pressure. The surface pressure is a value obtained by dividing the total load applied to the cleaning blade by the contact area of the cleaning blade with the member to be cleaned.

Description

Cleaning device, process cartridge, and image forming device

technical field

The present invention relates to an image forming apparatus such as a transfer machine, a printer, a facsimile machine, or a composite machine of these. Among them, in particular, it relates to an electrophotographic image forming apparatus that forms a toner image on an image carrier, transfers the toner image directly or indirectly, and records the image on a recording medium such as paper or OHP film. It also relates to a cleaning device for removing toner remaining on an image carrier after image reproduction in such an image forming apparatus. And it is related with the process cartridge which at least integrally includes a cleaning device and an image carrier, and these are attached to and detachable from the main body of an image forming apparatus together.

Background technique

Conventionally, in an image forming apparatus of an electrophotographic type, the peripheral surface of a roll-shaped and belt-shaped image carrier is uniformly charged by a charging device together with the rotation of the image carrier, and then written by an exposure device. An electrostatic latent image is formed, and the latent electrostatic image is visualized by attaching toner by a developing device to form a toner image on an image carrier. Then, after the toner image is transferred on the recording medium by the transfer device, the transferred image is fixed by the fixing device, and the image is recorded on the recording medium. The peripheral surface of the image carrier after the transfer of the toner image is cleaned by a cleaning device and used for forming an image on the image carrier again.

In cleaning devices, since the structure is generally simple and the cleaning performance is excellent, a cleaning blade made of an elastic material such as polyurethane rubber is used as a cleaning member. The peripheral surface of the image body is cleaned by clogging, peeling off and removing the toner remaining on the image body.

On the other hand, in such electrophotographic image forming apparatuses, there has been a strong demand for improvement in image quality in recent years, and in response to this demand, the reduction in particle size and spherical shape of the toner has been promoted, and spherical toner using the polymerization method has been promoted. Agents are used as the mainstream.

However, the reduction in particle size and spheroidization of the toner makes it difficult to completely remove the transfer residual toner using a cleaning blade, resulting in poor cleaning. This is because the toner generates torque at the position where the cleaning blade presses the image carrier, and the cleaning blade is pushed up so that the toner easily sneaks into the gap between the cleaning blade and the image carrier.

Therefore, in the case of using a toner whose particle size has been reduced and spheroidized, it is necessary to increase the pressing force of the cleaning blade against the image carrier to prevent infiltration of the toner. Conventionally, "line pressure" is generally used as a characteristic value indicating the force that prevents toner from sneaking into the cleaning blade. The "linear pressure" refers to the value "gf/cm" obtained by dividing the total load applied to the cleaning blade by the length of the front end corner line portion of the cleaning blade pressed against the image carrier.

Specifically, the front end of the scraper is formed into a rod state to press the front end of the cleaning scraper against the image carrier, and a sheet sensor with a thickness of 0.1 (mm) is sandwiched at the pressed position, and the output value (function) of the sensor is The value of dividing the load "g" at the pressing position by the axial length "cm" of the image bearing body at the pressing position.

In addition, the sheet sensor has a plurality of electrodes arranged in two directions (row direction, column direction) which are respectively perpendicular to each other inside, and its surface is covered with film resin. In these electrodes, the piezoresistive material and the charge generating material are arranged in a grid pattern, and when an external pressure is applied to the intersection points of the grid shape, the resistance value changes according to the load. Changes in this resistance value appear as changes in the current value flowing in the row and column directions, so the total load can be obtained from the current value.

However, if the "linear pressure" is increased, the cleaning performance of the small and spherical toner that is difficult to clean can be improved, but it causes the wear of the image carrier to be promoted, the driving torque of the image carrier to increase, and the cleaning blade to be damaged. Hazards such as increased plate wear.

In addition, this characteristic value "linear pressure" cannot sufficiently evaluate the ability to prevent toner from sneaking in. The reason is that in reality, at the pressing position of the cleaning blade, a clamping portion is formed between the image carrier, and the image carrier is not contacted with a line but with a surface, but as mentioned above, "line pressure" is given The value obtained by dividing the total load of the cleaning blade by the axial length of the image bearing body at the pressing position of the cleaning blade does not consider the contact area of the cleaning blade with the image bearing body at all.

That is, simply increasing the conventionally used characteristic value "linear pressure" does not necessarily clean the small and spherical toner, but instead causes damage such as accelerated image carrier wear and increased image carrier drive torque.

Here, as a new characteristic value representing the force of preventing toner from infiltrating, it is considered to use "face pressure" which is divided by the total load applied to the cleaning blade by the contact area of the cleaning blade with the image carrier. This "surface pressure" also changes according to the hardness, thickness, free length, shape, etc. of the rubber blade even when the same load is applied to the cleaning blade. Changes in shape, support method, etc.

For example, as shown in FIGS. 19(A) and (B), a cleaning device having cleaning blades 1a and 1B having different shapes is used. And, as shown in Figure 19 (A), a cleaning blade 1a is a flat blade shape, and its base end is adhered on one side and supported by the support member 2, and the front end corner portion 3a is pressed against the image carrier. 4 on. In addition, as shown in (B), the other cleaning blade 1B has a protrusion 5, and its base end is adhered to one side to be supported by the support member 2, and the front end corner portion 3B is pressed against the image carrier 4. superior. At this time, the protrusion 5 is brought into contact with the supporting member 2 to prevent the cleaning blade 1B from being bent and the blade tip being detached.

In such a cleaning device shown in FIG. 19(A), when a load is applied to the cleaning blade 1a, it is deformed as shown in the figure, and buckling due to stress concentration occurs at the front end position of the support member 2, and as shown in FIG. 20(A) ) shows that the front end a of the cleaning blade 1a is warped, and at the same time, the front end is in contact with the peripheral surface of the image carrier 4. Therefore, as shown in FIG. 21(A), the load is dispersed to form a small pressure distribution.

On the other hand, in the cleaning device shown in FIG. 19(B), even if a load is applied to the cleaning blade 1b, it is not deformed as shown in the figure, and it is not bent as shown in FIG. 20(B). The curved portion is pressed against the image carrier 4, as shown in FIG. 21(B), forming a large pressure distribution in which stress is concentrated at the tip of the cleaning blade 1b.

Thus, due to the difference in the shape of the cleaning blade, the contact area of the cleaning blade to the image carrier changes, and the surface pressure changes, resulting in a difference in cleaning performance.

Therefore, in the conventional cleaning apparatuses, for example, as described in Patent Document 1 and Patent Document 1, it has been proposed to consider the surface pressure. In addition, for example, as described in Patent Document 3 and Patent Document 4, it is proposed to form the blade edge into an obtuse angle. Also, as described in Patent Document 5, it is proposed to chamfer the blade edge with a curvature of 5 to 15 μm, and as described in Patent Document 6, it is proposed to form the blade into a tapered shape.

Patent Document 1: JP-A-2000-75527

Patent Document 2: Japanese Unexamined Patent Publication No. 11-237819

Patent Document 3: JP-A-2002-268487

Patent Document 4: Japanese Unexamined Patent Publication No. 5-19671

Patent Document 5: Japanese Unexamined Patent Publication No. 6-332350

Patent Document 6: Patent No. 2962843

However, none of Patent Documents 1 to 6 relates to a low linear pressure and high surface pressure cleaning structure capable of cleaning small and spherical toner particles.

Contents of the invention

The object of the present invention is to obtain a cleaning structure with low linear pressure and high surface pressure by specifying the material, shape and supporting structure of a cleaning blade (Blade) in a cleaning device, a process cartridge and an image forming device.

In order to achieve the above object, a first aspect of the present invention provides a cleaning device that presses the front end corner line portion of an elastic cleaning blade made of polyurethane rubber or the like supported by a support member as a blade fixing device to the surface moving side in the opposite direction. On the member to be cleaned, and opposite to the moving direction of the member to be cleaned, the toner on the surface of the member to be cleaned is removed, characterized in that the angle forming the front edge portion of the cleaning blade is formed as an obtuse angle , and when the thickness of the part of the cleaning blade that is pressed against the member to be cleaned is t1, and the free length of the cleaning blade is t3, a relationship of 1.75≦t3/t1≦3 is formed. Here, the so-called surface pressure refers to the value obtained by dividing the total load applied to the cleaning blade by the contact area of the cleaning blade with the member to be cleaned. The member to be cleaned includes, for example, an image carrier, a charging roller, and the like.

In the second aspect of the present invention, in the cleaning device described in the first aspect, the member to be cleaned is an image carrier such as a roll-shaped or belt-shaped photoreceptor or an intermediate transfer body, and the image remains on the carrier after image transfer. The toner on the image body is removed by the cleaning blade.

According to the third aspect of the present invention, in the cleaning device described in the first aspect or the second aspect, the obtuse angle forms a range from 95 degrees to 140 degrees.

According to a fourth aspect of the present invention, in the cleaning device according to the third aspect, the obtuse angle is formed by obliquely cutting the front end surface of the cleaning blade. It may be formed by oblique cutting when the cleaning blade is formed, or may be formed by oblique cutting after forming.

According to the fifth aspect of the present invention, in the cleaning device according to the fourth aspect, the cutting width when the front end surface of the cleaning blade is obliquely cut is 200 μm in the thickness direction of the cleaning blade, and is perpendicular to the thickness direction. 100 μm in the length direction.

According to a sixth aspect of the present invention, in the cleaning device according to any one of the first to fifth aspects, the surface pressure is formed to be greater than or equal to 3.0 MPa.

According to a seventh aspect of the present invention, in the cleaning device according to any one of the first to sixth aspects, the front edge portion is pressed against the member to be cleaned with a contact width greater than or equal to 10 μm. Here, the contact width refers to the width in the moving direction of the image carrier with which the leading edge corner portion contacts, that is, the so-called nip width.

According to an eighth aspect of the present invention, in the cleaning device according to any one of the first to seventh aspects, the front end corner line portion is pressed against the member to be cleaned with a contact width of less than or equal to 40 μm.

According to a ninth aspect of the present invention, in the cleaning device according to the eighth aspect, the front edge portion is pressed against the member to be cleaned with a contact width of 30 μm or less.

In the tenth aspect of the present invention, in the cleaning device according to any one of the first to ninth aspects, the cleaning blade is pressed against the cleaned part with a linear pressure ranging from 0.2N/cm to 1.2N/cm . Here, the linear pressure refers to the value obtained by dividing the total load applied to the cleaning blade by the length of the front end corner line portion of the cleaning blade pressed against the image carrier.

According to the eleventh aspect of the present invention, in the cleaning device according to the tenth aspect, the cleaning blade is pressed against the member to be cleaned with a linear pressure less than or equal to 0.9 N/cm.

According to the twelfth aspect of the present invention, in the cleaning device according to any one of the first to eleventh aspects, a protrusion is formed on the cleaning blade to prevent the front end of the cleaning blade from pressing against the member to be cleaned. The cleaning blade abuts against the supporting member when it is lifted up, and the cleaning blade is released. That is, the protruding portion abuts against the supporting member, thereby restricting the deflection of the cleaning blade.

In a thirteenth aspect of the present invention, in the cleaning device according to any one of the first to eleventh aspects, the thickness of the cleaning blade is t1, and the free length of the cleaning blade protruding from the support member is t3 , a relationship of 1.75≤t3/t1≤3 is formed.

In the fourteenth aspect of the present invention, in the cleaning device described in any one of the first to eleventh aspects, a reinforcing member is placed on the free length portion of the cleaning blade to prevent the front end of the cleaning blade from being pressed against the cleaning blade. When the cleaning blade is on the part to be cleaned, the cleaning blade is disengaged. That is, the deflection of the cleaning blade is restricted by adding the reinforcing member to the pad.

In a fifteenth aspect of the present invention, in the cleaning device according to any one of the first to eleventh aspects, rubber having a JISA hardness of 60 to 80 is used as a material of the cleaning blade.

In a sixteenth aspect of the present invention, in the cleaning device according to any one of the first to eleventh aspects, the resilience of the cleaning blade is formed to be less than or equal to 30% at 23°C.

According to the seventeenth aspect of the present invention, in the cleaning device according to any one of the first to sixteenth aspects, the front end edge portion of the cleaning blade is pressed against the member to be cleaned for low-friction treatment. And low friction coefficient.

In an eighteenth aspect of the present invention, in the cleaning device according to the seventeenth aspect, the front edge corners are impregnated with a fluororesin to lower the friction coefficient of the front edge corners.

In a nineteenth aspect of the present invention, in the cleaning device according to any one of the first to eighteenth aspects, the sphericity of the toner is formed to be greater than or equal to 0.95.

The twentieth aspect of the present invention provides a process cartridge, which is characterized in that at least integrally has the cleaning device according to any one of the second to nineteenth aspects and the image carrier, which can be freely moved relative to the image forming device. disassembly.

A twenty-first aspect of the present invention provides an image forming apparatus, characterized by having the cleaning device according to any one of the second to nineteenth aspects.

In a twenty-second aspect of the present invention, in the image forming apparatus described in the twenty-first aspect, a protective layer containing inorganic fine particles is provided on the image carrier.

According to a twenty-third aspect of the present invention, in the image forming apparatus according to the twenty-first aspect, the protective layer of the image carrier has an adhesive resin having a cross-linked structure.

In a twenty-fourth aspect of the present invention, in the image forming apparatus according to the twenty-third aspect, a charge transport layer is included in the structure of the binder resin.

In a twenty-fifth aspect of the present invention, in the image forming apparatus according to any one of the twenty-first to twenty-fourth aspects, there is a method of applying lubricant to the image carrier, for example, using a brush (Fa-Brush) or the like. Lubricant applicator for lubricants.

According to the first aspect of the present invention, since the angle of the front end corner line portion of the cleaning blade is formed as an obtuse angle, the line pressure can not be reduced by reducing the contact width, but the surface pressure can be increased. The surface pressure of MPa presses the front edge portion against the member to be cleaned, and even small and spherical toner particles can be reliably cleaned. That is, by specifying the shape of the cleaning blade, a cleaning structure with low linear pressure and high surface pressure can be obtained.

According to the second aspect of the present invention, since the member to be cleaned is an image carrier such as a photoreceptor and an intermediate transfer body, and the residual toner remaining on the image carrier after image transfer is removed by the cleaning blade, it is possible to Increasing the line pressure without reducing the contact width of the cleaning member to the image carrier, but increasing the surface pressure, can effectively prevent toner from slipping compared with the load applied to the cleaning member, and with an area greater than or equal to 2.0 The pressure presses the front corner portion against the image carrier, so the residual toner remaining on the image carrier after image transfer can be reliably cleaned. That is, by specifying the shape of the cleaning blade, a cleaning structure with low linear pressure and high surface pressure can be obtained.

According to the third aspect of the present invention, since the obtuse angle is formed in a range from 95 degrees to 140 degrees, the surface pressure can be increased more reliably without reducing the contact width to increase the line pressure.

According to the fourth aspect of the present invention, furthermore, since the front end surface of the cleaning blade is cut obliquely, the angle forming the front edge portion can be more easily formed into an obtuse angle, and the surface pressure can be improved by increasing the line pressure without reducing the contact width. .

According to the fifth aspect of the present invention, furthermore, the cutting width when cutting the front end surface of the cleaning blade obliquely is 200 μm in the thickness direction of the cleaning blade and 100 μm in the longitudinal direction, so that the front end edge can be formed more reliably. The angle of the portion is formed as an obtuse angle, and the surface pressure can be increased without reducing the contact width to increase the line pressure.

According to the sixth aspect of the present invention, further, since the surface pressure is also set to be greater than or equal to 3.0 MPa, it is possible to better clean the small and spherical toner.

According to the seventh aspect of the present invention, furthermore, since the front end edge portion is pressed against the member to be cleaned with a contact width greater than or equal to 10 μm, there will be no uneven contact between the cleaning blade and the member to be cleaned, or the impact of the cleaning blade on the member to be cleaned. If the surface of the cleaning member is damaged or affected by protrusions, etc., the cleaning will be poor, but small and spherical toner particles can be cleaned well.

According to the eighth aspect of the present invention, furthermore, since the front end corner portion is pressed against the member to be cleaned with a contact width of 40 μm or less, the surface pressure is increased without increasing the line pressure, and the abrasion of the member to be cleaned is not promoted. Either the increase in the driving torque of the member to be cleaned or the increase in the wear of the cleaning blade can improve the cleaning performance of the small and spherical toner that is difficult to clean.

According to the ninth aspect of the present invention, furthermore, since the front corner portion is pressed against the member to be cleaned with a contact width of 30 μm or less, the surface pressure can be increased more reliably without increasing the line pressure.

According to the tenth aspect of the present invention, since the cleaning blade is pressed against the member to be cleaned with a linear pressure in the range of 0.2 N/cm to 1.2 N/cm, it is possible to ensure the cleaning performance of the small and spherical toner. , Eliminate the hazards caused by excessive increase in line voltage.

According to the eleventh aspect of the present invention, since the cleaning blade is pressed against the part to be cleaned with a linear pressure less than or equal to 0.9 N/cm, it is possible to more reliably prevent damage caused by excessively high linear pressure.

According to the twelfth aspect of the present invention, furthermore, since the protrusion is formed on the cleaning blade, the front end of the cleaning blade is prevented from coming off when it abuts against the supporting member when it is pressed against the member to be cleaned, and the belly of the cleaning member is suppressed. The reduction of surface pressure due to contact can provide a cleaning structure with low linear pressure and high surface pressure by specifying the shape of the cleaning blade.

According to the thirteenth aspect of the present invention, since the relationship of 1.75≦t3/t1≦3 is formed when the thickness of the cleaning blade is t1 and the free length of the cleaning blade protruding from the supporting member is t3, it is possible to suppress The reduction of the surface pressure due to the belly contact of the cleaning member is achieved by specifying the shape of the cleaning blade to obtain a cleaning structure with low linear pressure and high surface pressure.

According to the fourteenth aspect of the present invention, further, since a reinforcing member is placed on the free length portion of the cleaning blade, the cleaning blade is prevented from detaching when the front end of the cleaning blade is pressed against the image carrier, so that the cleaning member is suppressed. In order to reduce the surface pressure due to belly contact, a cleaning structure with low linear pressure and high surface pressure can be obtained by specifying the shape of the cleaning blade.

According to the fifteenth aspect of the present invention, further, since rubber having a JISA hardness of 60 to 80 degrees is used as the material of the cleaning blade, it is possible to suppress the decrease in the surface pressure caused by the belly contact of the cleaning member. The material of the scraper is specific to obtain a cleaning structure with low linear pressure and high surface pressure.

According to the sixteenth aspect of the present invention, since the resilience of the cleaning blade is formed to be 30% or less at 23° C., stick-slip of the cleaning blade can be prevented, wear of the cleaning blade can be suppressed, and by cleaning The material of the scraper is specific to obtain a cleaning structure with low linear pressure and high surface pressure.

According to the present invention, as described above, since the angle of the front edge portion of the cleaning blade is formed as an obtuse angle, the surface pressure can be increased without reducing the contact width to increase the line pressure, which is comparable to the load applied to the cleaning member. I prevent the slipping of the toner efficiently. In addition, since the front edge portion is pressed against the member to be cleaned with a surface pressure of 2.0 MPa or more, even small and spherical toner particles can be reliably cleaned. However, on the other hand, due to the high surface pressure, any increase in the frictional resistance also increases the driving torque of the cleaned part. Especially when it is applied to the tandem-type photoreceptor cleaning device that has become the mainstream in the recent color image forming apparatuses, simply increase the drive torque by an amount corresponding to the number of photoreceptors, so that the drive for driving the photoreceptors The increase in the size of the motor hinders the miniaturization of the entire device and increases the cost.

And according to the seventeenth aspect of the present invention, since the front end corner line portion of the cleaning blade pressed on the cleaned part is made to have a low friction coefficient, the frictional resistance of the cleaning blade to the cleaned part can be reduced, and the friction of the cleaned part can be reduced. The driving torque is suppressed to be small, and the increase in size of the driving motor is prevented, which prevents the cost from increasing.

According to the eighteenth aspect of the present invention, since the front end corners are impregnated with a fluorine-based resin to lower the friction coefficient of the front corners, the frictional resistance of the cleaning blade to the parts to be cleaned can be reduced in a simple way, and the parts to be cleaned will be reduced. The driving torque of the cleaning member is suppressed to be small.

According to the nineteenth aspect of the present invention, furthermore, since the sphericity of the toner is formed to be greater than or equal to 0.95, reliable cleaning can be performed by a cleaning structure with low linear pressure and high surface pressure, and good cleaning performance can be obtained. image quality.

According to the twentieth aspect of the present invention, at least one of the cleaning device and the image carrier according to any one of the first to sixteenth aspects can be provided, and it can be freely attached to and detached from the image forming apparatus, so reliable cleaning can be achieved. A process cartridge with a clean structure for small and spherical toner, low linear pressure, and high surface pressure. In addition, by forming the process cartridge, maintenance such as replacement, repair, and replenishment can be easily performed, and the main body of the image forming apparatus can be downsized.

According to the twenty-first aspect of the present invention, since it is the image forming apparatus provided with the cleaning device according to any one of the first to sixteenth aspects, it is possible to provide a low-line cleaning device capable of reliably cleaning small and spherical toner particles. Image forming apparatus with a clean structure of high pressure and high surface pressure.

According to the twenty-second aspect of the present invention, further, since the protective layer containing inorganic fine particles is provided on the image carrier, it is possible to provide an image forming apparatus in which the abrasion resistance of the image carrier is improved.

According to the twenty-third aspect of the present invention, furthermore, since the protective layer of the image carrier has the binder resin having a cross-linked structure, it is also possible to provide an image forming apparatus in which the wear resistance of the image carrier is improved.

According to the twenty-fourth aspect of the present invention, furthermore, since the charge transport layer is included in the structure of the binder resin, it is possible to provide an image forming apparatus having an image carrier with improved electrical stability.

According to the twenty-fifth aspect of the present invention, furthermore, since the lubricant coating device is provided for coating the lubricant on the image carrier, it is possible to improve the image forming apparatus with less peeling of the film of the image carrier and improved durability.

Description of drawings

1 is a schematic internal composition of a direct-transfer type monochrome image forming apparatus having a cleaning device of the present invention;

Fig. 2 is a partially enlarged structural diagram of an image carrier on the image forming device;

Fig. 3 is the position relationship figure of image carrier and charging device;

Fig. 4 (A) shows the projected shape of the actual toner, (B) shows the perfect circle shape with the same area;

Figure 5 is an enlarged view of the cleaning device;

Figure 6 is an enlarged view of another example of the cleaning device;

7(A) is an enlarged view showing the front end of the cleaning blade when the front end surface of the cleaning blade is partially cut away, and (B) is an enlarged view showing the front end of the cleaning blade when the front end surface of the cleaning blade is completely cut;

8(A) is a cleaning blade A of a comparative example, (B) is a cleaning blade B of the present invention, (C) is a support structure diagram of a conventional cleaning blade C as a comparative example, and (D) is An enlarged view of the front end of the cleaning scraper B of the present invention;

Fig. 9 is a graph showing the relationship between the linear pressure of the cleaning blades A, B, and C shown in Fig. 8 and the width of the clamping portion;

Fig. 10 is the relationship diagram between the line pressure and the surface pressure of these cleaning blades A, B, C;

Fig. 11 is a structural diagram of the cleaning blade supporting structure when the free length and thickness of the cleaning blade have a certain relationship;

12(A) is a blade support structure diagram showing the case where the angle at which the front end corner line portion of the cleaning blade is formed is 90 degrees, and (B) is a view showing the case where the angle at which the front end corner line portion of the cleaning blade is formed is an obtuse angle. Scraper support structure diagram;

Fig. 13 (A) is an example of the situation where the reinforcing component pad is added on the cleaning scraper, and (B) is the supporting structure diagram of the scraper of other examples;

14 is a schematic internal composition diagram of an example of an image forming apparatus having a lubricant applying device;

Fig. 15 is a schematic inner picture composition of other examples;

Fig. 16(A) is a view of the scraper support structure before low friction coefficient, and (B) is a view of the scraper support structure after low friction coefficient;

17 is a schematic configuration diagram of an intermediate transfer unit having an intermediate transfer body as a member to be cleaned and its surroundings;

Fig. 18 is a schematic configuration diagram of a charging device having a charging roller as a member to be cleaned and its surroundings;

Fig. 19 (A), (B) is the support structure diagram of the cleaning blade of different shape in the past;

20(A), (B) are enlarged views of the front end of the squeegee pressed against the image carrier;

21(A) and (B) are pressure distribution diagrams in this state.

Symbol Description

10 image carrier (parts to be cleaned)

16 cleaning device

23 charge transport layer

24 layers of protection

37 supporting parts

38 cleaning scraper

38b front edge corner

40 protrusion

41 reinforcement parts

42 lubricant coating device

111 transfer roller (cleaned part)

210 intermediate transfer belt (cleaned parts)

θ is the angle formed by the corner line of the front end

Detailed ways

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

FIG. 1 shows a direct transfer type monochrome image forming apparatus provided with a cleaning device of the present invention.

The symbol 10 in the figure may be a belt, but in this embodiment it is a roll-shaped image carrier, which rotates clockwise in the figure. Around the image bearing body 10, the exposure device 12 and the developing device 13 are arranged on the right side clockwise from the charging device 11 on the upper side, the transfer device 14 is arranged on the lower side, and the static elimination device 15 is arranged on the left side. Device 16 etc. On the lower side of the image carrier 10, there is provided a recording medium transport path 17 for transporting recording media such as paper, OHP film, etc. from the right side to the left side via a transfer position with the transfer device 14. A fixing device 18 is provided downstream of the transfer position on the recording medium transport path 17 .

Along with the rotation of the image carrier 10 , while the roller-shaped charging member is rotated by the charging device 11 , the peripheral surface of the image carrier 10 is uniformly charged to a predetermined polarity. Next, writing is performed by the exposure device 12 to form an electrostatic latent image on the charged region of the image carrier 10 . Thereafter, toner is adhered by the developing device 13 , the electrostatic latent image is visualized, and a toner image is formed on the image carrier 10 .

On the other hand, the recording medium drawn out from the unillustrated paper feeding cassette etc. is conveyed through the recording medium conveying path 17, and is aligned with the toner image position on the image carrier 10 at the same time as the rotation time of the image carrier 10. Feed to the lower side of the image carrier 10. Then, at the transfer position, the toner image on the image carrier 10 is transferred onto the recording medium by the transfer device 14 while conveying the recording medium. The recording medium after the image transfer is mechanically separated from the image carrier 10, continues to be transported through the recording medium transport path 17, and the transferred image is fixed by the fixing device 18 at a downstream position, and is discharged to a paper discharge stacking device not shown in the figure. .

The peripheral surface of the image carrier 10 after the image transfer is destaticized by the static elimination device 15, and the residual toner remaining on the image carrier 10 after the image transfer is removed by the cleaning device 16, starting from the charging device 11. Image is formed again.

(About the structure of the image carrier 10)

The image carrier 10 used in this embodiment is a negatively chargeable organic image carrier with improved abrasion resistance, and a photosensitive layer and the like are provided on a roll-shaped conductive support with a diameter of 30 [mm]. Figure 2 shows its partial section. A base layer 21 as an insulating layer is provided on a conductive support 20 as a base layer. A charge generating layer (CGL) 22 and a charge transporting layer (CTL) 23 as a photosensitive layer are provided thereon. Then, a protective layer (FR) 24 constituting the surface of the image carrier 10 is laminated thereon.

(conductive support 20)

As the conductive support 20 , a substance showing conductivity with a volume resistance of 10 ¹⁰ Ω·cm or less can be used. For example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, and metal oxides such as tin oxide and indium oxide can be used to coat the film or cylinder by vapor deposition or sputtering. Shaped plastic, paper products, or scrapers such as aluminum, aluminum alloy, nickel, stainless steel, etc., and they are obtained by cutting, superfinishing, grinding and other surface treatments after forming tube blanks by extrusion and drawing processes tube etc. Alternatively, an endless nickel belt or an endless stainless steel belt disclosed in JP-A-52-36016 may be used as the conductive support 20 .

In addition, conductive powder is dispersed in a suitable binder resin on the support having the above-mentioned structure, and then coated, and used as the conductive support 20 . Examples of the conductive powder include metal powders such as carbon black, acetylene black, aluminum, nickel, iron, nickel chromium, copper, zinc, and silver, and metal oxide powders such as conductive tin oxide and ITO. In addition, the adhesive resin used at the same time includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, chlorine Ethylene-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin , polyvinyl formal resin, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, alkyd resin and other thermoplastic, thermosetting resin or photocurable resin. Such a conductive layer is provided by dispersing these conductive powders and a binder resin in, for example, tetrahydrofuran, methylene chloride, methyl ethyl ketone, toluene, etc., by coating.

In addition, on a suitable cylindrical substrate, use polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorine rubber, Teflon (registered trademark) and other raw materials containing the above-mentioned conductive The heat-shrinkable tube of conductive powder is provided with a conductive layer, and can be used as the conductive support 20 well.

Next, the photosensitive layer will be described. The photosensitive layer may be a single layer or a stacked layer, but for convenience of description, first, the stacked structure of the charge generation layer 22 and the charge transport layer 23 will be described.

<Charge generation layer 22>

The charge generating layer 22 is a layer mainly composed of a charge generating substance. A known charge-generating substance can be used for the charge-generating layer 22 . Representative examples of charge generating substances include monoazo pigments, disazo pigments, trisazo pigments, perylene pigments, perylenequinone pigments, quinacridine pigments, quinone condensed polycyclic compounds, and squaric acids. Dyes, other phthalocyanine-based pigments, naphthalocyanine-based pigments, azirenium salt-based dyes, and the like are preferable. These charge generating substances may be used alone or in combination of two or more.

In the charge generating layer 22, the charge generating material can be mixed with the bonding resin by ball mill, vertical ball mill, sand mill, ultrasonic wave, etc., and coated on the conductive support 20 or the primer layer 21, formed by drying.

In the charge generating layer 22, the above-mentioned charge generating substance may be dispersed in the binder resin as needed. Examples of adhesive resins that can be used include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral resin, polyvinyl formal resin , polyvinyltoluene, polyvinyl ketone, polystyrene, polysulfone, poly-N-vinylcarbazole, polyacrylamide, polyvinylbenzylene, polyester, phenoxy resin, vinyl chloride-vinyl acetate Copolymer, polyvinyl acetate, polyphenylene ether, polyamide, polyvinylpyridine, cellulose resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, etc. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight, based on 100 parts by weight of the charge generating material. The binder resin may be added either before dispersion or after dispersion.

Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, Monochlorobenzene, cyclohexane, toluene, xylene, volatile oil, etc., especially ketone solvents, ester solvents, and ether solvents are preferably used. These may be used individually or in mixture of 2 or more types.

The charge generating layer 22 is mainly composed of a charge generating material, a solvent, and an adhesive resin, but may contain any additives such as a photosensitizer, a dispersant, a surfactant, and silicone oil.

As the coating method of the coating liquid, methods such as dip coating, spray coating, heat coating, nozzle coating, spin coating, and ring coating can be used. The film thickness of the charge generating layer 22 is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

<Charge transport layer 23>

The charge transporting layer 23 is formed by dissolving or dispersing a charge transporting substance and a binder resin in a suitable solvent, applying them on the charge generating layer 22 and drying them. In addition, one or more types of plasticizers, leveling agents, antioxidants, etc. may be added as needed.

The charge transporting substances include positive hole transporting substances and electron transporting substances.

Examples of electron transporting substances include chloranil, bromoquinone, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7 -Tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothiaxanthone, 2,6,8-trinitro-4H Electron-accepting substances such as indeno[1,2-B]thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and benzoquinone derivatives.

Examples of positive pore transport substances include poly-N-vinylcarbazole and its derivatives, poly-γ-carbazole ethyl glutamate and its derivatives, pyrene-formaldehyde condensate and its derivatives , polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, homogeneous Stilbene derivatives, α-phenyl stilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styryl anthracene derivatives, pyrazoline derivatives, Vinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bistilbene derivatives, enamine derivatives, etc., and other known materials. These charge-transporting substances may be used alone or in combination of two or more.

Examples of the binder resin include styrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl acetal Formaldehyde resin, polyvinyltoluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, alkyd resin and other thermoplastic or thermosetting resins.

The amount of the charge transporting substance is suitably 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. In addition, the thickness of the charge transport layer is preferably 25 μm or less in terms of resolution and responsiveness. The lower limit value varies depending on the system used (especially charging potential, etc.), but it is preferably 5 μm or more.

Examples of the solvent used here include tetrahydrofuran, dioxane, toluene, methylene chloride, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like. These may be used individually or in mixture of 2 or more types.

Next, the case where the photosensitive layer has a single-layer structure is described. The photosensitive layer is formed by dissolving or dispersing the above-mentioned charge generating substance, charge transporting substance, and binder resin in a suitable solvent, coating it on the conductive support 50 or the undercoat layer 51, and drying it. The charge-transporting substance may not be included, but may be composed of a charge-generating substance and a binder resin. In addition, a plasticizer, a leveling agent, an antioxidant, and the like may be added as needed.

As the binder resin, in addition to the binder resins listed above for the charge transport material 23 , the binder resins listed for the charge generating layer may be mixed and used. Of course, it is also preferable to use the polymeric charge-transporting substances listed above. The amount of the charge transporting substance is preferably 5 to 40 parts by mass relative to 100 parts by mass of the binder resin, preferably 0 to 190 parts by mass, and more preferably 50 to 150 parts by mass.

The photosensitive layer is a coating solution dispersed with a disperser, etc., using solvents such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane together with a charge-generating substance, a binder resin, and a charge-transporting substance. Formed by spray coating, heating coating, ring coating, etc. The film thickness of the photosensitive layer is about 5 to 25 μm is appropriate.

<Undercoat 21>

In the image carrier 10 of the illustrated example, an undercoat layer 21 is provided between the conductive support 20 and the photosensitive layer. The undercoat layer 21 generally has a resin as a main component, and when it is considered that the photosensitive layer is coated with a solvent on these resins, it is desirable to use a resin having high solvent resistance to common organic solvents. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate; alcohol-soluble resins such as copolymerized nylon and methoxymethylated nylon; polyurethane, melamine resin, phenolic resin, alkyd- Melamine resin, epoxy resin and other thermosetting resins that form a three-dimensional network structure. In the undercoat layer 21 , fine powder pigments of metal oxides such as titanium oxide, silicon dioxide, aluminum oxide, zirconium oxide, tin oxide, and indium oxide may be added in order to prevent wrinkles and a decrease in residual potential. In addition, these undercoat layers 21 can be formed using appropriate solvents and coating methods like the above-mentioned photosensitive layers. In addition, as the undercoat layer 21 shown in the figure, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, etc. can also be used. In addition, Al ₂ O ₃ , or organic substances such as parylene (prenyne), or inorganic substances such as SiO ₂ , SnO ₂ , TiO ₂ , ITO, and CeO ₂ are provided on the undercoat layer 21 by anodic oxidation. A vacuum thin film preparation setup is also preferred. In addition, known ones can also be used. The film thickness of the undercoat layer 21 is suitably 0 to 5 μm.

<The first example of the protective layer 24>

In order to prevent mechanical wear on the outermost layer of the image carrier 10, a protective layer 24 may also be provided. For example, an image carrier whose surface is coated with amorphous silicon in order to improve wear resistance, or an organic image carrier in which an outermost layer such as aluminum oxide or tin oxide is dispersed on the surface of the charge transport layer 23 may also be used. A protective layer 24 containing inorganic fine particles may also be provided.

As described above, the structure of the image carrier 10 used in this example is not limited to a specific structure. A one-layer structure in which only a photosensitive layer having a charge generating substance and a charge transporting substance as main components is provided on the conductive support 20; The laminated structure of the charge transport layer with the substance as the main component; or the structure in which the photosensitive layer with the charge generating material and the charge transport material as the main component is provided on the conductive support 20, and a protective layer is provided thereon; A charge-generating layer mainly composed of a charge-generating substance and a charge-transporting layer mainly composed of a charge-transporting substance are laminated on a conductive support, and a protective layer is provided on the charge-transporting layer; or, a conductive support is laminated. Image carriers having various layer structures such as a charge transporting layer mainly composed of a charge transporting substance, a charge generating layer mainly composed of a charge generating substance, and a structure in which a protective layer is provided on the charge generating layer are preferably used.

<The second example of the protective layer 24>

In addition, it is also effective to use a protective layer having an adhesive resin having a crosslinked structure on the protective layer 24 . In order to form a cross-linked structure, a reactive monomer having multiple cross-linkable functional groups in one molecule is used, and a cross-linking reaction occurs with light or heat energy to form a ternary network structure. This network structure exhibits high wear resistance as an adhesive resin.

From the viewpoint of electrical stability, brush resistance, and lifetime, it is very effective to use all or part of the monomer having charge transport capability as the above-mentioned reactive monomer. By using such a monomer, charge transport sites can be formed in the network structure, and the function as the protective layer 24 can be fully exhibited.

Examples of reactive monomers having charge-transporting ability include compounds containing at least one silicon atom having a charge-transporting component and a hydrolyzable substituent in the same molecule, and compounds containing a charge-transporting component and a hydroxyl group in the same molecule. A compound containing a charge-transporting component and a carboxyl group in the same molecule, a compound containing a charge-transporting component and an epoxy group in the same molecule, a compound containing a charge-transporting component and an isocyanate group in the same molecule. The charge transporting materials having these reactive groups may be used alone or in combination of two or more.

As a monomer having charge-transporting ability, one with high electrical and chemical stability is more preferable, and it is effective to use a reactive monomer having a triarylamine structure in view of fast carrier mobility and the like.

In addition, monofunctional and bifunctional polymerizable monomers and polymerizable Oligomer. As these polymerizable monomers and oligomers, known ones can be used.

In addition, in the illustrated example, the polymerization or crosslinking of the positive hole transport compound is carried out by heat or light, but when the polymerization reaction is carried out by heat, it can be mentioned that the polymerization reaction is carried out only by heat energy and an initiator must be used, but In order to carry out the reaction more efficiently at lower temperatures, addition of an initiator is preferred.

When photopolymerization is performed, it is preferable to use ultraviolet light as the light, but since the reaction is particularly rare only by light energy, a photopolymerization initiator is generally used in combination. The so-called photopolymerization initiator at this time mainly refers to an initiator that absorbs ultraviolet light with a wavelength of 400 nm or less, generates active species such as free radicals or ions, and initiates polymerization. In addition, in this example, the thermal and photopolymerization initiators mentioned above may be used in combination.

The charge-transporting layer 23 having such a formed network structure has high abrasion resistance, but volume shrinkage increases during the crosslinking reaction to form a relatively thick film, which may cause cracks or the like. In this case, when the protective layer has a laminated structure, the lower layer (photosensitive layer side) may use a low-molecular dispersion polymer protective layer, and the upper layer (surface side) may form a protective layer having a cross-linked structure.

For example, in the electrophotographic image carrier, the electrophotographic image carrier A was produced in the same manner except that the protective layer coating liquid, film thickness and production conditions were replaced by the following.

Mix 182 parts of methyltrimethoxysilane, 40 parts of dimethyloltriphenylamine, 225 parts of 2-propanol, 106 parts of 2% acetic acid, and 1 part of aluminum triacetylethoxide to prepare a protective layer for coating liquid. The coating liquid was applied on the above-mentioned charge transporting layer 23, dried, and cured by heating at 110° C. for 1 hour to form a protective layer 24 with a film thickness of 3 μm.

In addition, in the electrophotographic image carrier, the electrophotographic image carrier B was produced in the same manner except that the protective layer coating solution, film thickness and production conditions were replaced by the following.

Dissolve 30 parts of the positive hole transport compound (the following formula 1), acrylic monomer (the following formula 2) and 0.6 parts of the photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) in monochloro In a mixed solution of 50 parts of benzene/50 parts of dichloromethane, it is formulated as a coating for surface protection. This paint was sprayed on the previous charge transport layer 23 and cured for 30 seconds with a metal halide lamp at a light intensity of 500 mW/cm ² to form a surface protection layer 24 with a film thickness of 5 μm.

[chemical 1]

[Chem 2]

(About charging device 11)

An example of the structure of the charging device 11 shown in the drawing is shown.

Conventionally, as a charging device, there is a device using a corona charging method using corona discharge. In the corona charging method, the charging line is placed close to the object to be charged, and a high voltage is applied to the charging line to generate a corona discharge between the charging line and the object to be charged, thereby charging the object to be charged. However, in the case of the corona charging method, discharge generating substances such as ozone and nitrogen oxides (NO _x ) are generated along with corona discharge. Since the discharge-generated substance forms a nitric acid or nitrate film that adversely affects the image carrier during image formation, its generation should be avoided as much as possible.

Therefore, in recent years, instead of the corona discharge method, the development of a contact charging method or a proximity charging method that generates less discharge-generated substances and enables low-power charging has been actively developed. In these methods, a charging member such as a roller, a brush, or a blade is placed in contact with or close to a charged body such as an image carrier, and a voltage is applied to the charging member to charge the surface of the charged body. According to this method, compared with the corona charging method, since there is less generation of discharge generation substances and lower power can be achieved, the practicality is high. In addition, since a large charging device is not required, it is possible to reduce the size of the device, which meets the demand for a smaller device.

In the illustrated example, a non-contact roller charging method shown below is used as an example of realizing the above-mentioned requirements for lower power consumption, lower risk reduction, and smaller size.

In addition, in the case of using a spherical toner, as described above, poor cleaning tends to occur more easily than conventional powder lump toners. In an image forming apparatus that can clean a spherical toner from an accumulated layer of amorphous toner, if a toner defect occurs, if the non-contact roller charging method is used, the toner due to the cleaning defect will not adhere. On the charging device, it does not cause abnormal images generated by abnormal charging.

The charging device in the illustrated example charges the image carrier 10 by applying an AC discharge generated by non-contact approaching charging members arranged oppositely. In addition, there is also a method of charging the image bearing member 10 by contacting the charging member arranged oppositely with an AC applied discharge. In the case of using this method, it is preferable to increase the contact between the surface of the image carrier 10 and the charging member, and to use an elastic member that does not apply mechanical pressure to the image carrier 10 . However, if the elastic member is used, the width of the charging nip portion will be enlarged, and thus the protective substance will easily adhere to the charging roller side. In this way, the method of non-contact charging is advantageous in improving the durability of the charged body.

3 shows the positional relationship between the image carrier 10 and the charging device 11 at the charging position, and the charging device 11 has a charging roller 26 as a charging member, a spacer 27, a spring 28, a power source 30, and the like. On the charging roller 26, a shaft portion 26A and a roller portion 26b as a charging portion are provided. Among them, the roller portion 26 b faces the image carrier 10 , has a function of charging the surface of the image carrier 10 , and is rotatable by rotation of the shaft portion 26A. The roller portion 26 b of the charging roller 26 is disposed opposite to the surface of the image carrier 10 with a slight gap, and a spacer 27 as a gap maintaining member is provided on the charging roller 26 . Through this spacer 27 , a portion facing the image forming region A on the surface of the image carrier 10 on which an image is formed is arranged without being in contact with the image carrier 10 . The dimension in the longitudinal direction of the roller portion 26b is set to be longer than the image forming region of the image carrier 10, and the aforementioned minute gap c is formed by abutting the spacer 27 on the non-image forming region b of the image carrier 10. The charging roller 26 rotates around the surface of the image bearing member 10 through the spacer 27 and continuously. The minute gap c constituting the closest portion between the charging roller portion 26b and the image carrier 10 is 1 to 100 μm. The closest distance is preferably 30 to 65 μm.

A spring 28 for pressing the charging roller 26A against the charged body is attached to the shaft portion 26A. Thereby, the above-mentioned small gap c can be maintained with high precision.

A power supply 30 for charging is connected to the charging roller 26 . The power source 30 uniformly charges the surface of the image carrier 10 by applying an AC discharge to the minute gap between the surface of the image carrier 10 and the surface of the charging roller 26 . In this embodiment, an alternating voltage in which an AC voltage as an alternating component is superimposed on a DC voltage as a direct current component is applied to the charging roller 26. By using an alternating voltage, influences such as fluctuations in charging potential that cause minute gap fluctuations are suppressed, enabling uniform charging.

The charging roller 26 is composed of a core bar of a cylindrical conductive support and a resistance adjustment layer formed on the outer peripheral surface of the core bar. In this embodiment, the diameter of the charging roller 26 is formed to be 10 mm.

The surface of the charging roller 26 can be made of a known material such as a rubber member, but is preferably made of a resin material. If a rubber member is used, it is difficult to maintain a small gap with the image carrier 10 due to water absorption and deflection of the rubber. Depending on image forming conditions, only the central portion of the charging roller 26 can contact the surface of the image bearing body 10 suddenly. It is difficult to cope with the disturbance of the surface layer of the image carrier 10 caused by such local and sudden contact of the charging roller 26 to the image carrier 10 . Therefore, when charging the image carrier 10 by the non-contact charging method, it is preferable to use a hard material capable of uniformly maintaining a small gap between the charging roller and the image carrier.

<Surface layer of charging roller>

As the hard material for the surface of the charging roller 26, for example, the following materials can be used. As the resistance adjustment layer, it can be formed of a thermoplastic resin composition (polyethylene, polypropylene, polymethyl methacrylate, polystyrene and its copolymer, etc.) dispersed with a polymer ion conductive agent. Cured film treatment and the like are performed. The curing coating treatment is performed by, for example, immersing the resistance adjustment layer in a treatment solution containing an isocyanate compound. Alternatively, the surface of the resistance adjustment layer may be modified to form a cured coating layer.

(developing device 13)

As shown in FIG. 1, in the developing device 13, there are, for example, inside the developing housing 32: an agitating and conveying member 33 for agitating and conveying the developer, a developer replenishing roller 34 for replenishing the developer conveyed by it, and a developer replenishing roller 34 for replenishing the developer therefrom. Toner of the developer adheres to the developing roller 35 on the image carrier 10 , and a thinning member (not shown) that thins the developer on the developing roller 35 before adhering to the image carrier 10 .

In recent years, image forming apparatuses that use toner to form images have been required to form high-definition images with higher precision, and the demand for high resolution has increased. As a method for achieving high resolution, it is known to be effective to use a spherical toner having a reduced particle diameter and a nearly spherical shape. Therefore, a spherical toner having a sphericity of 0.95 or more is used in the developing device 13 in order to improve image quality.

The "sphericity" here is the average sphericity measured by a flow-type sample image resolution device FPIA-2000 (manufactured by Toa Medical Electronics Co., Ltd. (Toa Medical Electronics Co., Ltd.), trade name). Specifically, in the 100-150ml of water in the container from which impurities and solids have been removed in advance, a surfactant is added as a dispersant, preferably 0.1-0.5ml of alkylbenzene sulfonate, and another 0.1-0.5g left and right measurement samples (toner). Then, the toner-dispersed suspension was subjected to dispersion treatment for more than 1 to 3 minutes by an ultrasonic disperser to make the concentration of the dispersion liquid 3000 to 10,000/μl, and the resultant was set in the above-mentioned analyzer to measure the concentration of the toner. Toner shape and distribution. And, based on the measurement result, the outer circumference of the actual toner projected shape shown in FIG. When the outer circumference of the shown perfect circle is L2, L2/L1 is obtained, and the average value thereof is defined as the sphericity.

As the spherical toner, a toner obtained by heat-treating a distorted irregular toner (powder toner) by the currently widely used powder agglomerate method, and a toner produced by a polymerization method can be used. Toner etc.

(cleaning device)

For example, as shown in FIG. 5 , the cleaning device 16 adheres one side of a blade-shaped supporting member 37 as a blade fixing device to the base end of an elastic cleaning blade 38, and presses its front end corner portion 38b against the image carrier. 10 weeks. For the cleaning blade 38 , for example, rubber having a JISA hardness of 60 to 80 degrees and a material having a recovery elasticity of 30% or less at 23° C. is used. Furthermore, it is formed in the shape of a thin and long blade along the axial direction of the image carrier 10 . The cleaning scraper 38 is not limited to the above-mentioned shape, and can also, for example, as shown in FIG. 6 , fit and adhere the front end of the supporting member 37 on its base end step to form a shape with a protrusion 40 to prevent the front end corner portion 38b from When the image carrier 10 is pressed, it comes into contact with the support member 37 and the cleaning blade 38 is released in the direction of the arrow.

Here, the angle θ of the cleaning blade 38 forming the front end ridgeline portion 38b forms an obtuse angle by obliquely cutting a part of the front end surface 38c to form a cutting surface 38A as shown in FIG. 7(A), for example. In addition, as shown in FIG. 7(B), the entire front end surface 38c may be cut obliquely so that the entire front end surface 38c is a cut surface 38A, and the angle θ forming the front end ridgeline portion 38b may be formed as an obtuse angle. The obtuse angle is preferably in the range of 95 degrees to 140 degrees. And, the cleaning blade 38 presses the front end corner line portion 38 b against the image carrier 10 with a surface pressure equal to or equal to 2.0 MPa. Ideally, it is greater than or equal to 3.0 MPa.

The surface pressure necessary for cleaning the spherical toner will be described in detail below. The surface pressure is a value obtained by dividing the total load applied when the cleaning blade 38 is pressed against the image carrier 10 by the contact area between the cleaning blade 38 and the image carrier 10 . The contact area between the cleaning blade 38 and the image carrier 10 can be easily obtained by measuring the contact area when the cleaning blade 38 is pressed against a transparent dummy image carrier.

The following experiment is an experiment showing the results of different cleaning performances due to different surface pressures when the same load (linear pressure) is applied. Specifically, when a certain load (linear pressure) is applied to the cleaning blade 38, the contact Area change, calculate the surface pressure at this time, and adjust the relationship with the cleaning performance.

(Experiment: Surface pressure and cleaning performance)

Table 1 below shows the results of calculating the surface pressure by observing the contact area between the cleaning blade and the image carrier when a certain load was applied to the cleaning blade. Specifically, since the length in the main scanning direction in which the cleaning blade is in contact with the image carrier is determined, the contact width between the image carrier and the cleaning blade is obtained from the observed image, and the contact width is divided by the line pressure (g/cm). value.

Here, the cleaning performance shown in Table 1 was judged with reference to the remaining toner amount on the surface of the image bearing member after cleaning. The symbol ◎ in the table indicates the case of complete cleaning, ○ indicates the case where a very small amount of toner remains, △ indicates the case of partial streaky cleaning failure or the case where some toner remains on the entire surface, and × indicates the case of the entire surface. When there are streaks or a large amount of toner remaining on the surface.

Line pressure (N/cm) Contact length (μm) Surface pressure (MPa) cleanliness 1.20 5 24.00 △ 1.20 10 12.00 ○ 1.20 20 6.00 ◎ 1.20 30 4.00 ◎ 1.20 50 2.40 ○ 1.20 60 2.00 ○ 0.95 5 19.00 △ 0.95 10 9.50 ○ 0.95 20 4.75 ◎ 0.95 30 3.17 ◎ 0.95 50 1.90 ×

Line pressure (N/cm) Contact length (μm) Surface pressure (MPa) cleanliness 0.95 60 1.58 × 0.95 90 1.06 × 0.40 5 8.00 △ 0.40 10 4.00 ○ 0.40 20 2.00 ○ 0.40 30 1.33 × 0.40 40 1.00 × 0.40 50 0.80 × 0.20 5 4.00 △ 0.20 10 2.00 △ 0.20 20 1.00 ×

In this experiment, the line pressure was varied between 0.2 and 1.2 N/cm, and the contact width was varied between 5 and 90 μm. When a linear pressure of 1.2 N/cm is applied to the blade, good cleaning performance (⊚ or ○) can be obtained between a surface pressure of 2.4 to 12.0 MPa. On the contrary, poor cleaning occurred at a surface pressure of 2.4 MPa. This is because the contact width is as narrow as 5 μm, and contact unevenness occurs mainly in the main scanning direction in view of the accuracy of the image carrier, and sufficient surface pressure cannot be applied locally. In addition, when a line pressure of 0.95N/cm is applied to the scraper, good cleaning performance can be obtained under a surface pressure of 3.17-9.50MPa, but under a surface pressure of 1.9MPa, due to the narrow contact width of 5μm, it will still Poor cleaning due to uneven contact. In addition, poor cleaning occurs at a surface pressure of 1.9 MPa or less.

In addition, when the line pressure is 0.4N/cm, good cleaning performance can be obtained under the surface pressure of 2.0-4.0MPa, but under the surface pressure (non-uniform contact) of 8.0MPa and the surface pressure less than or equal to 1.33MPa, Poor cleaning occurs.

From the above results, it can be judged that even if the same linear pressure is applied, the load per unit area, that is, the surface pressure (MPa) is different according to the contact state (contact area) between the cleaning blade and the image carrier, and when the linear pressure is set When it is high, the spherical toner cannot be cleaned if the surface pressure is low.

In addition, from the results in Table 1, by setting the surface pressure to be greater than or equal to 2.0 MPa, the spherical toner can be cleaned, but when the contact width is about 10 μm, or when the surface pressure is about 2.0 MPa, the toner remains Less (○), and can not be completely clean. This is because the smaller the contact area, the more high surface pressure can be applied, but when the contact width between the scraper and the image carrier is too narrow, due to uneven contact with the image carrier and damage to the surface of the image carrier, protrusions, etc. It is easy to cause poor cleaning. In order to clean the toner balls, as shown in FIGS. 5 and 6, it is desirable to set the surface pressure to 2.0 MPa or more, preferably 3.0 MPa or more, and set the contact width to 10 μm or more.

As described above, in order to clean the spherical toner, it is necessary to set the contact width between the blade and the image carrier to be 10 μm or more and the surface pressure to be 2.0 MPa or more, preferably 3.0 MPa or more. Here, in order to suppress film peeling of the image carrier, an increase in the driving torque of the image carrier, blade wear, etc., it is desirable to set the contact width to be 10 μm or more and 40 μm or less, preferably 30 μm or less . The reason is that even when the contact width between the blade and the image carrier is very large (for example, a contact width of 100 μm), if the surface pressure is greater than or equal to 2.0 MPa or greater than or equal to 3.0 MPa, the formation of the spherical toner is prevented. Invasive and clean. However, for example, when the contact width is 100 μm, in order to set the surface pressure to 2.0 MPa, it is necessary to apply a linear pressure of 2.0 N/cm, which requires a very large linear pressure. In order to clean the spherical toner, it is necessary to minimize the contact area between the blade and the image carrier, and to apply a high surface pressure with a small linear pressure as much as possible. In order to prevent the intrusion of the spherical toner, the precision of the image carrier and the particle size of the toner are also taken into consideration. It is preferable to set the contact width between the image carrier and the scraper to be greater than or equal to 10 μm, but the upper limit value is set to It is less than or equal to 40 μm, preferably less than or equal to 30 μm, and the linear pressure applied to make the surface pressure greater than or equal to 2.0 MPa or greater than or equal to 3.0 MPa can be set between 0.2 and 1.2 N/cm. It is best to set the line pressure to be less than or equal to 0.9N/cm.

Next, it will be described that by forming the front end of the cleaning blade 38 at an obtuse angle, compared with the case where the front end of the blade is 90 degrees, the linear pressure is smaller and the surface pressure for preventing the entry of the spherical toner can be applied.

As mentioned above, in order to clean the spherical toner, it is necessary to abut the blade against the image carrier with a surface pressure of 2.0 MPa or more, but when the same surface pressure is applied, due to the shape of the blade, the The load (line pressure) of the entire scraper is different. Since the linear pressure has a great influence on the size of the driving torque of the image carrier, the life of the image carrier 10 and the wear of the cleaning blade 38, the linear pressure should be reduced as much as possible.

In order to clean the spherical toner, it is possible to apply a larger linear pressure than that used to clean the conventional powder block toner. Therefore, the material of the cleaning blade has been considered, and the elimination of the front end of the support member has been studied. Squeegee shape that can apply high linear pressure due to buckling of the cleaning blade.

However, as described above, the toner removal performance is determined not by the line pressure but by the surface pressure. Therefore, studies have been made on a blade shape in which a surface pressure of 2.0 MPa necessary to clean a spherical toner is applied with a lower linear pressure. As a result, by processing the front end corner portion 38b of the cleaning blade 38 in pressure contact with the image carrier 10 into an obtuse angle, compared with the case where the front end corner portion 38b is formed at 90 degrees, it is possible to apply a lower line pressure and clean it. Surface pressure of spherical toner. That is, by processing the front end corner portion 38b into an obtuse angle, when the same load is applied, compared with the case where the front end corner portion 38b is 90 degrees, the warpage of the cut surface of the blade is reduced, and the contact area is reduced, so it is possible to improve And the resistance per unit area is the surface pressure.

Next, regarding the cleaning blade A of the front end resistance-concentrated shape shown in FIG. Three types of obtuse-angle cleaning blade B with the tip resistance concentrated shape shown in (C) and conventional powder block toner cleaning blade C shown in (C) explain the relationship between line pressure and contact width, and line pressure and surface pressure. .

First, the shape of the squeegee A, B, and C for comparing the linear pressure and the contact width will be described. The squeegee C is attached to one side of the support member 37 with a thickness of 2 mm, a free length from the tip of the support member 37 to the tip of the squeegee 7 mm, and a JISA hardness of 70 degrees.

Next, the scraper A and the obtuse-angled scraper B of the front-end resistance-concentrated shape will be described. First, the squeegee A and the squeegee B have a common shape to effectively apply a high surface pressure to the tip of the squeegee to prevent belly contact that causes a drop in surface pressure. That is, as shown in FIGS. 8(A) and (B), the scraper A and the scraper B are tightly bonded to the supporting member 37 to form a protrusion 40, which prevents contact with the front edge corner line portion 38b when it is pressed against the image carrier. The support member 37 abuts and the cleaning blade escapes. That is, to form a substantially convex shape, it is composed of a thicker portion at the center and thinner portions at both ends, and is supported by making the stepped portions of the thicker portion and the thinner portion tightly bonded to the support member 37 . By forming the shape of the blade in this way, buckling of the blade at the front end of the support member 37 can be prevented, so that the cleaning blade is prevented from coming into contact with the abdomen of the image carrier, and the load can be concentrated on the blade tip.

Specifically, the scraper shapes of scraper A and scraper B are t1=1.7mm, t2=3.5mm, t3=7mm, t4=11mm, L=3.8mm, d=1.2mm, and the thickness of the supporting member 37 is T=1.6mm, JISA hardness is 70 degrees.

In addition, in the case of the obtuse-angled blade B, in addition to the above-mentioned structure, it has a shape in which the front edge portion 38b of the blade is cut into an obtuse angle as in FIG. 7(A). Specifically, as shown in FIG. 8(D), by cutting 100 μm in the longitudinal direction and 200 μm in the thickness direction, the angle θ forming the front end ridge line portion 38 b is formed as an obtuse angle.

FIG. 9 shows the relationship between the linear pressure and the contact width of the above three scrapers A, B, and C, and FIG. 10 shows the relationship between the linear pressure and the surface pressure of the above three scrapers A, B, and C.

As shown in Figure 9, when a certain linear pressure is applied, comparing the contact widths of the three types of scrapers A, B, and C, the scraper C is comparable to the other two types of scrapers A, B with the front-end resistance concentration shape. Compared with that, due to the formation of abdominal contact, the contact width increases. On the other hand, when comparing the contact widths of the squeegee A and B with two kinds of front-end resistance-concentrated shapes abutting against the image carrier, the squeegee B with the front end of the squeegee cut at an obtuse angle is compared with the squeegee A without processing. , the contact width is smaller, and the lower pressure is easy to increase under the same line pressure.

Fig. 10 is a graph showing the relationship between the linear pressure and the surface pressure (obtained from Fig. 9 except for the linear pressure and the contact width) of the respective scrapers A, B, and C.

In the conventional scraper C for powder block toner, increasing the displacement d of the scraper against the image carrier and increasing the line pressure only increases the contact area, but the surface pressure cannot be sufficiently increased. Large, resulting in poor cleaning. On the other hand, when the displacement amount d is increased for the blades A and B having the shape where the resistance is concentrated at the front end, the contact width does not increase due to the belly contact, so the surface pressure necessary for cleaning the spherical toner can be applied. Here, the surface pressure necessary to clean the spherical toner is, as described above, equal to or greater than 2.0 MPa, preferably equal to or greater than 3.0 MPa.

In addition, comparing the squeegee A and B, the squeegee B having the tip of the squeegee processed into an obtuse angle can apply a high surface pressure with a lower linear pressure than the squeegee A.

In the scraper A, in order to apply the minimum surface pressure of 2.0MPa necessary to clean the toner on the image carrier (○), it is necessary to apply a linear pressure of about 0.2N/cm, in order to form a surface pressure that can be completely cleaned (◎) 3.0MPa, need to apply a line pressure of about 0.3N/cm. On the other hand, in the squeegee B, it is necessary to apply a linear pressure of approximately 0.4 N/cm to apply a surface pressure of 2.0 MPa, and to apply a linear pressure of approximately 0.6 to 0.8 N/cm to apply a surface pressure of 3.00 MPa. In this way, by processing the tip of the blade into an obtuse angle, it is possible to apply a large surface pressure with a smaller linear pressure. For example, the linear pressure to be applied so that the surface pressure of the completely cleanable toner is 3.0 MPa can be set as low as about 0.3 to 0.5 N/cm.

In this way, by forming the front end of the squeegee at an obtuse angle, it is possible to reduce the contact area between the sheet and the image carrier compared to the case where the front end is 90 degrees. In the results shown in FIGS. 9 and 10 , only the front end portion of the squeegee B was cut into 100 μm×200 μm (the angle is greater than 115 degrees), forming an obtuse angle. That is, as shown in FIG. 7(A) and (B), if the entire cut surface is cut at an obtuse angle, the contact width can be narrowed compared to the case of 90 degrees. Here, the so-called obtuse angle refers to an angle greater than 90 degrees, greater than or equal to 95 degrees and less than or equal to 140 degrees. If the tip angle is close to 90 degrees, the effect of reducing the contact area due to the obtuse angle cannot be exerted. In addition, the cleaning blade was incorporated into the device by setting the initial contact angle β shown in FIGS. 5 and 6 to be between 15 degrees and 30 degrees. Therefore, when the tip angle is 140 degrees and the initial contact angle is 30 degrees, the angle formed by the cutting surface and the scraper is 10 degrees. If the angle is small, the toner accumulates on the wedge portion, and since the contact area between the blade and the image carrier substantially increases, the surface pressure decreases, resulting in poor cleaning.

FIG. 11 shows a specific example of the cleaning blade shown in FIG. 5 . In this example, the cleaning blade 38 is formed in an elongated shape, and has a shape satisfying the relationship of 1.75≦t3/t1≦3 between the free length t3 and the thickness t1. In this way, buckling of the cleaning blade 38 at the front end portion of the support member 37 can be prevented.

In addition, the shape of the scraper for cleaning powder lump toner is, for example, free length t3 = 8 mm, thickness t1 = 2 mm (t3 / t1 = 4), due to buckling and abdominal contact, it is impossible to apply the cleaning required for spherical toner. However, by setting a shape that satisfies the above relational expression, buckling of the cleaning blade 38 at the front end portion of the support member 37 can be suppressed.

Here, in the elongated shape shown in FIG. 11 that is thicker than the conventional amount, when the angle θ forming the front end corner portion 38b of the sheet is formed as an obtuse angle, the contact area between the sheet and the image carrier is similarly reduced, and the contact area with the image carrier is reduced. Compared with the case where the angle of the leading edge corner line portion 38b of the forming sheet is 90 degrees, the surface pressure for cleaning the spherical toner can be applied with a lower linear pressure.

The following shows the linear pressure and surface pressure of the squeegee D (Fig. 12(A)) with the tip of the squeegee at 90 degrees and the squeegee E (Fig. 12(B)) with the tip processed into an obtuse angle (100μm×200μm) Relationship. Here, the shape of the blade before the obtuse processing is thicker than usual, and is a long blade shape with t1=3.6mm and t3=7mm (t3/t1≈1.95).

The blade C shown in FIG. 8(C) cannot apply the surface pressure necessary for cleaning the spherical toner, but the blades D and E can apply the surface pressure of 2.0 MPa and 3.0 MPa necessary for cleaning the spherical toner. . In addition, the cleaning blade E can apply the surface pressure necessary for cleaning spherical toner even with a lower line pressure than the blade D by making the angle θ forming the front end ridge line portion 38b of the blade an obtuse angle.

As shown in FIGS. 7(A) and (B), the same effect can be obtained regardless of whether the scraper E shown in FIG. 12(B) cuts the entire front end surface of the cutting sheet or cuts a part thereof.

In addition, the rubber hardness of the squeegee of the present invention may be between 60 and 80 degrees in JISA hardness as described above. When the hardness is set to be 60 degrees or less, buckling of the sheet at the tip of the supporting member occurs, and sufficient surface pressure cannot be applied. Conversely, when the rubber hardness is too high, the adhesiveness to the image carrier deteriorates, and a location where sufficient surface pressure cannot be applied locally occurs, resulting in poor cleaning.

Next, the blade support structure using a reinforcing member will be described.

FIG. 13(A) provides a cleaning blade 38 having the same thickness as a supporting member 37 having a thickness of 2 mm, and attaches the blade to a reinforcing member 41 to form a free length of the blade to 3 mm. The same metal material as the supporting member 37 is provided as the reinforcing member 41 . The free length can be appropriately selected and is not limited to the above-mentioned length. In addition, the material used for the reinforcing member 41 is not limited to the above-mentioned materials, and it is preferable to use a material having a hardness greater than or equal to that of the sheet.

In addition, in FIG. 13(B), a reinforcing member 41 thinner than the supporting member 37 having a thickness of 2 mm is attached to the scraper 38 . In FIG. 13(B), the reinforcing member 41 is not attached up to the front end of the scraper 38, but the present invention is not limited thereto, and the length of the reinforcing member 41 can be set arbitrarily.

Next, the resilience of the cleaning blade 38 will be described.

In the present invention, the recovery elasticity of the elastic material used for the cleaning blade 38 is set to be 30% or less at 23°C. The reasons for setting the resilience to 30% or less are as follows. First, in order to clean the spherical toner, a cleaning blade with less vibration at the tip of the blade is preferable. Second, relative to the wear of the scraper, it is better to clean the scraper with low resilience.

In the past, when cleaning powdery toner, the scraper has the function of bouncing the toner that comes into contact with the front end of the scraper. Therefore, when the elastic modulus of recovery is low, there is a problem that the bouncing effect cannot be fully exerted. However, in the case of a spherical toner, the flying effect does not work because the blade slips off until the toner bounces back. When the recovery elasticity is high, when the front end of the scraper is easy to slightly vibrate relative to the image carrier, the sliding of the spherical toner is promoted instead.

On the other hand, low resilience is advantageous against scraper wear. That is, during repeated image formation, the cleaning blade is gradually worn by sliding friction with the image carrier. The scraper wear generation mechanism should consider the result of the stick-slip motion of the scraper itself, the tearing of the polymer (such as urethane rubber) constituting the scraper, and the result of fatigue damage to generate wear. In such a case, the front end portion of the blade is torn to pieces, thereby causing poor cleaning.

In the case of reduced resilience, since the stick-slip motion of the squeegee itself is suppressed, even after repeated imaging processes, the accumulated vibration frequency of the front end of the squeegee is smaller than that of a squeegee with high resilience, and fatigue damage can be suppressed. As a result, the blade is not worn even through repeated image forming steps, and the cleaning performance can be maintained favorably over a long period of time.

For the above two reasons, it is necessary to set the recovery elasticity to be 30% or less at 23°C.

In the present invention, in order to clean the spherical toner, the cleaning blade 38 is pressed against the image carrier 10 under a high load. Accordingly, abrasion of the blade and film peeling of the image carrier increase. Here, by applying a lubricant to the surface of the image carrier 10 , abrasion of the blade 38 and peeling of the film of the image carrier 10 can be suppressed. In addition, when the image carrier 10 is charged by the above-mentioned charging device 11 using discharge, the surface of the image carrier 10 is gradually modified by the discharge to increase the surface energy. At this time, since the cleaning failure of the spherical toner tends to occur, the modification of the surface of the image carrier 10 is suppressed by applying a lubricating material, so that the cleaning performance of the spherical toner can be maintained for a long time. Therefore, the image forming apparatus of the present invention may also include a lubricant application device for applying lubricant to the image carrier 10 .

Fig. 14 shows an example of a lubricant. The lubricant application device 42 shown in FIG. 14 molds the lubricant 43 into a solid shape, presses the lubricant 43 against the brush 45 by the pressure spring 44, and rotates the brush 45 to apply the lubricant 43 on the surface of the image carrier 10 . In addition, there is also a method of supplying a powdery lubricant accumulator to the image carrier by arranging it to face the surface of the image carrier. In FIG. 14 , the position where the lubricating material is applied is on the upstream side of the cleaning blade 38 with respect to the moving direction of the image carrier 10 . At this time, the lubricating material may be removed together with the toner removed by the scraper 38 , and a lubricating material film may not be uniformly formed on the surface of the image carrier 10 .

As shown in FIG. 15, a lubricant application device 42 is arranged downstream of the cleaning blade 38 and upstream of the charging device 11. The lubricant is applied by the lubricant application device 42. Since the lubricant is coated on the surface of the image body 10, it can be evenly coated. In addition, preferably, as shown in the figure, a stretching member 46 for stretching the lubricating material coated on the surface of the image bearing member 10 is disposed downstream of the lubricating material applying device 42 . As the stretching member 46 , an elastic body such as a urethane rubber blade, an elastic roller, or the like may be brought into contact with the image carrier 10 with an appropriate pressure.

As the lubricating material 43, it is preferable to use scraper-like crystalline powder such as zinc stearate. Scraper-like crystals have a self-organized layered structure of amphiphilic solvate molecules, and when a shear force is applied, the crystals are broken and easily slide between layers. This action is effective in reducing the coefficient of friction. As the lubricating material 43, other substances such as various fatty acid salts, waxes, and silicone oils may be used in addition to the above.

Examples of fatty acids include undecanoic acid, dodecanoic acid, tridecanoic acid, myristic acid, hexadecanoic acid, pentadecanoic acid, octadecanoic acid, heptadecanoic acid, arachidic acid, oil acid, arachidic acid, caprylic acid, capric acid, caproic acid, etc., and examples of the metal salt thereof include salts of metals such as zinc, iron, magnesium, aluminum, and calcium.

Next, the case where the coefficient of friction of the front end corner line portion 38b of the cleaning blade 38 having an obtuse angle shape is reduced will be described.

Specifically, as shown in FIG. 16(A), a cleaning blade 38 made of elastic rubber is supported by a support member 37 . To clean the scraper 38, set the free length of the bottom of the scraper to 7mm and the free length of the top of the scraper to 8.8mm with a thickness of 3.6mm in order not to buckle. The angle θ of the portion 38b forms an obtuse angle shape. By forming such a blade shape, as described above, the contact width between the cleaning blade 38 and the image carrier 10 is appropriately set to ensure a surface pressure of 2.0 to 3.0 MPa necessary for cleaning spherical toner.

The cleaning blade 38 lowers the coefficient of friction of the leading edge portion 38 b pressed against the image carrier 10 as a member to be cleaned, thereby reducing the friction coefficient with the image carrier 10 . Specifically, as shown in FIG. 16(B), a coating p for lowering the coefficient of friction can be implemented on the surface of the cleaning blade 38, but it is preferable that the cleaning blade 38 is impregnated with fluorine to reduce the friction coefficient. The coefficient of friction can be reduced by impregnating fluorine into the blade to maintain the effect of reducing the coefficient of friction over time.

The effect of the treatment for reducing the coefficient of friction at the tip of the cleaning blade 38 will be described below.

Generally, the linear pressure that the cleaning blade 38 is pressed on the image carrier 10 is set as f (N/cm), and the width of the cleaning blade 38 in the longitudinal direction is set as L (cm), then the cleaning blade 38 is pressed The total load N=f×L(g) on the image bearing body 10 . At this time, if the coefficient of friction between the cleaning blade 38 and the image bearing body 10 is set to μ, then the frictional force F=μN acting between the cleaning blade 38 and the image bearing body 10 .

Here, the torque T generated due to the sliding friction between the image carrier 10 and the cleaning blade 38 is given by using the radius r of the image carrier 10

T=r×F=r×μN

express. The shape and material of the scraper are the same, and in the case of the same diameter of the contacting image carrier, a certain total load N must be applied to apply the surface pressure necessary to clean the spherical toner.

Therefore, it is necessary to reduce the coefficient of friction μ between the cleaning blade 38 and the image carrier 10 in order to reduce the torque T while maintaining the necessary load for cleaning the spherical toner. Conventionally, as a method of reducing the friction coefficient μ of the surface of the image carrier 10, a method of applying a lubricant or the like is known. However, according to the results of our research, the torque does not necessarily decrease when the lubricant is applied. Experimental results showing one example are as follows.

Example 2

In the image forming process of the AC superimposed roller charging method, the transition between the cleaning blade 38 and the image carrier 10 is performed when zinc stearate is coated on the surface of the image carrier 10 and when zinc stearate is not coated. moment.

(experimental conditions)

Cleaning blade 38 : A cleaning blade (thickness 2mm, free length 7mm) using the existing powder block toner

(Length in the longitudinal direction of the cleaning blade: 325mm)

When measuring the cleaning action using a Jupiter machine, compare the average values.

The diameter of the image carrier 10: φ30

(result)

Table 2

condition Torque (kg cm) Zinc stearate coating without 1.3 Coated with zinc stearate 1.9

As shown in the table, when zinc stearate was applied as a lubricant, the torque increased on the contrary. The reason for this is that when a lubricant is applied to reduce the surface of the image carrier 10, zinc stearate is also degraded by the discharge of the charging device, and the lubricity is lost, and the surface energy of the image carrier 10 surface is reversed. etc. increase, as a result, the torque of the sliding friction between the cleaning blade 38 and the image carrier 10 becomes larger.

In this way, even if a lubricant is applied on the surface of the image carrier 10, in order to maintain the low μ state of the image carrier 10 surface, the coating amount of zinc stearate is optimized, and the lubricating effect of zinc stearate exceeds that of stearate. The coating balance of the increase of the surface energy due to the deterioration of the acid zinc is necessary, so the surface of the image carrier 10 coated with the lubricant is reduced, and the torque between the cleaning blade 38 and the image carrier 10 is reduced. difficult.

Therefore, as a result of repeated image forming processes, in order to reduce the friction coefficient μ between the surface of the image bearing member 10 and the cleaning blade 38 which changes, reducing the friction coefficient of the cleaning blade 38 itself is to lower the cleaning blade 38 more stably. and the method of torque between the image carrier 10.

Next, the results of a comparative experiment will be described regarding the effect of reducing the driving torque of the image carrier 10 that occurs when the front end corner portion 38b of the cleaning blade 38 slides against the image carrier 10 when the coefficient of friction is reduced. .

(Example 3)

In this experiment, torque values generated during the cleaning operation were measured under the following conditions 1 to 3, and their magnitude relationships were compared.

(experimental conditions)

Cleaning blade A: A conventional cleaning blade for block toner (thickness 2mm, free length 7mm, shape as shown in Fig. 8(C))

Cleaning scraper B: front end obtuse angle scraper (shape as Fig. 13(A))

Cleaning scraper C: Scraper with an obtuse angle at the front end, which reduces the friction coefficient of the front end (the shape is shown in Figure 13(B))

(Note: The length of the cleaning blades of A, B, and C in the length direction: 325mm)

Image carrier: φ30

(result)

table 3

toner piece Line pressure (N/cm) Torque (kgf cm) Condition 1 powder block toner Scraper A (for powder block) 0.2 1.8 Condition 2 spherical toner Scraper B 0.95 3.8 Condition 3 spherical toner Scraper C (low μ treatment) 0.95 2.7

For comparison, the torque when the powder lump toner is cleaned by a conventional cleaning blade (Condition 1) was set to be about 1.8 (kgf·cm). On the other hand, in the scraper B whose front end is processed into an obtuse angle to apply a surface pressure of 2.0 to 3.0 MPa required for cleaning spherical toners, when a linear pressure of 0.95 N/cm is applied, the torque is about 3.8 kgf·cm, which is the same as Condition 1 is greater than or equal to twice the torque.

In condition 3, when blade C was used with low μ treatment at the tip of blade B, the torque was about 2.7 kgf·cm when a linear pressure of 0.95 N/cm was applied, and the torque could be reduced.

In this way, by reducing the friction coefficient of the front end corner portion 38b of the cleaning blade 38, even when a load capable of cleaning spherical toner is applied, the friction generated by the sliding friction between the image carrier 10 and the cleaning blade 38 can be reduced. torque. Here, the method of impregnating the blade with fluorine is used as a method of reducing the coefficient of friction of the front end corner portion 38 b of the cleaning blade 38 . At this time, in order to impregnate the fluororesin from the surface of the blade to the inside, the coefficient of friction can be reduced for a long time.

On the other hand, it is also possible to apply a material for reducing the coefficient of friction on the surface of the blade. In addition, the cleaning blade 38 is not limited to this as long as the coefficient of friction is smaller than conventionally used polyurethane.

In the image forming apparatus of the present invention, at least the above-mentioned cleaning device 16 and the image carrier 10 may be provided integrally to form a process cartridge that can be attached and detached from the main body of the image forming apparatus. Accordingly, it is possible to provide a process cartridge having a low linear pressure and high surface pressure cleaning structure capable of reliably cleaning small and spherical toner particles. Also, by forming a process cartridge, maintenance such as replacement, repair, and replenishment can be easily performed, and the main body of the image forming apparatus can be downsized.

In the above example, the image forming apparatus of the direct transfer method in which the toner image formed on the photoreceptor as the image carrier is directly transferred to the recording medium without passing through the intermediate transfer body has been described. And the case of the process cartridge and the cleaning device, of course, can be applied to the image of the direct transfer method in which the toner image formed on the photoreceptor as the image carrier is transferred to the recording medium through the intermediate transfer body to record the image. A device is formed with its processing cartridge and cleaning device. In this case, needless to say, the primary cleaning device for removing the primary transfer residual toner on the photoreceptor as the image carrier can also be applied to remove the secondary transfer residual toner on the photoreceptor as the image carrier. Agent secondary cleaning device.

In addition, although the description is applied to a monochrome image forming apparatus, its process cartridge, and cleaning device, it can be similarly applied to rotary and tandem color image forming apparatuses, their process cartridges, and cleaning apparatus. It can also be applied similarly to the case where a plurality of process cartridges and cleaning devices are provided.

It is possible to provide an image forming apparatus, a process cartridge thereof, and a cleaning device having a low linear pressure and high surface pressure cleaning structure capable of reliably cleaning small and spherical toner particles.

FIG. 17 shows a schematic structure of an intermediate transfer unit 300 having an intermediate transfer body as a member to be cleaned and its surroundings. A case where the present invention is applied to a secondary cleaning device for removing secondary residual toner on intermediate transfer belt 210 as an intermediate transfer body will be described based on this FIG. 17 .

The intermediate transfer unit 300 hangs the intermediate transfer belt 210 around the tension roller 214, the drive roller 215, the post-secondary transfer support roller 216, and the four intermediate transfer bias rollers 62Y, 62C of yellow, cyan, deep red, and black. , 62M, 62K, three ground rollers 74, etc., a belt cleaning device 217 is provided around as a secondary cleaning device.

The intermediate transfer belt 210 is circularly moved clockwise in the drawing by the rotation of the driving roller 215 driven by a belt driving electrode not shown. The four intermediate transfer bias rollers 62Y, 62C, 62M, and 62K are provided in contact with the base layer side (inner peripheral surface side) of the intermediate transfer belt 210 , and receive an intermediate transfer bias voltage from a power source (not shown). In addition, the intermediate transfer belt 210 is pressed from the base layer side to the photoreceptors 101Y, 101C, 101M, and 101K to form intermediate transfer nip portions, respectively. An intermediate transfer electric field is formed between the photoreceptor and the intermediate transfer bias roller at each intermediate transfer nip due to the influence of the above-mentioned intermediate transfer bias. The Y toner image formed on the photoreceptor 101Y for Y is intermediate-transferred onto the intermediate transfer belt 210 under the influence of the intermediate transfer electric field and the nip pressure. The C, M, and K toner images formed on the C, M, and K photoreceptors 101C, 101M, and 101K are superimposed on the Y toner image and intermediate transferred. A four-color superposed toner image (hereinafter referred to as a four-color toner image) that is a multiple toner image is formed on the intermediate transfer belt 210 by this superimposed intermediate transfer.

In the intermediate transfer belt 210 , ground rollers 74 abut against each of the portions located between the intermediate transfer nips from the inner side. These ground rollers 74 are made of a conductive material. Furthermore, each intermediate transfer nip prevents current generated by the intermediate transfer bias transmitted from the intermediate transfer bias rollers 62Y, 62C, 62M, and 62K to the belt from leaking to other intermediate transfer nips and process cartridges.

The four-color toner images superimposedly transferred onto the intermediate transfer belt 210 are secondarily transferred to a transfer paper (not shown) by a second transfer nip described later. The transfer residual toner that remains on the surface of the intermediate transfer belt 210 after passing through the secondary transfer nip passes through the elastic rubber of the belt cleaning device 217 that sandwiches the belt between the driving roller 215 on the left side in the drawing. Made cleaning blade 38 and cleaned.

The cleaning blade 38 is supported by a support member (not shown), and its front end is pressed against the intermediate transfer belt 210 whose surface moves in the opposite direction. The front end corner portion of the cleaning blade 38 is the same as the above-mentioned embodiment, and the angle forming the front end corner portion is constituted as an obtuse angle, and at the same time, it is pressed against the intermediate transfer belt 210 as the member to be cleaned with a surface pressure of 2.0 MPa or more. superior.

In particular, in the intermediate transfer unit 300 carrying toners of a plurality of colors like the intermediate transfer belt 210 , by removing transfer residual toner well, it is possible to prevent transfer residual toner of different colors from adhering. Color mixing caused on photoreceptor 1.

In addition, the intermediate transfer unit 300 includes at least the belt cleaning device 217 and the intermediate transfer belt 210 integrally to form a process cartridge, and thus can be attached to and detached from the main body of the image forming device (not shown).

In FIG. 17 , reference numeral 220 is an imaging device, which is composed of four monochromatic imaging devices 218Y, 218C, 218M, and 218K of yellow, cyan, magenta, and black. 102 is a resist roller, 222 is a secondary transfer conveyance device, and the transfer conveyance belt 224 is wound around two rollers 223 . 50 is a fixing device.

In the above example, it has been described that the member to be cleaned is the image carrier 10, 210 such as a photoreceptor and an intermediate transfer body, and the residue remaining on the image carrier 10, 210 after image transfer is removed by the cleaning blade 38. The condition of the toner. However, the member to be cleaned is not limited to the image carrier, and may be, for example, a charging roller of a charging device.

Fig. 18 shows a schematic configuration of a charging device having a charging roller as a member to be cleaned and its surroundings. As shown in the figure, the charging device 110 has a charging roller cleaning device 117 for removing toner adhering to the charging roller 111 . The charging roller cleaning device 117 has a destaticizing case 113 , a support member 37 , a cleaning blade 38 as an elastic body cleaning blade, a destaticizing recovery screw 114 , and the like.

Of the remaining toner adhering to the photoreceptor 101 , the toner that is not completely removed by the photoreceptor cleaning device reaches the opposite portion of the charging roller 111 as a charging area. Since the charging roller 111 approaches or contacts the photoreceptor 101 to be charged, some of the toner reaching the charging area adheres to the charging roller 111 . The toner adhering to the charging roller 111 in the charging area is removed from the surface of the charging roller 111 by the cleaning blade 38 of the charging roller cleaning device 117 .

The cleaning blade 38 is supported by the supporting member 37, and its front end is pressed against the charging roller 111 which moves on the surface in the opposite direction. The front end corner of the cleaning blade 38 is the same as the above example, and the angle forming the front end corner is formed as an obtuse angle, and is pressed against the charging roller 111 as the member to be cleaned with a surface pressure greater than or equal to 2.0 MPa.

By satisfactorily removing the residual toner adhering to the charging roller 111 , it is not necessary to form a non-contact type for preventing toner adhesion, and a contact type charging roller 111 can be used. In addition, the charging device 110 constitutes a process cartridge by integrating at least the charging roller cleaning device 117 and the charging roller 111 , so that it can be attached to and detached from the main body of the image forming device (not shown).

Claims (28)

1. cleaning device, it will be pressed on the parts that are cleaned that move on the surface round about by the front end knuckle line portion of the flexible cleaning scraper plate of support unit supporting, remove the lip-deep toner of these parts that are cleaned, it is characterized in that, the angle of the formation front end knuckle line portion of described cleaning balde is formed the obtuse angle, and, when the drift that is made as t1, described cleaning balde at the thickness with the component crimping part of being cleaned with described cleaning balde is made as t3, form the relation of 1.75≤t3/t1≤3.

2. cleaning device as claimed in claim 1 is characterized in that, to press more than or equal to the face of 2.0MPa described front end knuckle line portion by being pressed on the described parts that are cleaned.

3. cleaning device as claimed in claim 1 is characterized in that, the described parts that are cleaned are image carriers, by the toner that still remains in after the transfer printing of described cleaning balde removal image on this image carrier.

4. cleaning device as claimed in claim 1 is characterized in that, described obtuse angle forms from 95 to be spent to the scope of 140 degree.

5. cleaning device as claimed in claim 3 is characterized in that, the front end face by the described cleaning balde of inclined cut forms described obtuse angle.

6. cleaning device as claimed in claim 5 is characterized in that, cutting width is 200 μ m on the thickness direction of described cleaning balde, is 100 μ m in the longitudinal direction.

7. cleaning device as claimed in claim 2 is characterized in that, described pressure is more than or equal to 3.0MPa.

8. cleaning device as claimed in claim 1 is characterized in that, with more than or equal to the contact width of 10 μ m with described front end knuckle line portion by being pressed on the described parts that are cleaned.

9. cleaning device as claimed in claim 1 is characterized in that, with the contact width that is less than or equal to 40 μ m with described front end knuckle line portion by being pressed on the described parts that are cleaned.

10. cleaning device as claimed in claim 9 is characterized in that, with the contact width that is less than or equal to 30 μ m with described front end knuckle line portion by being pressed on the described parts that are cleaned.

11. cleaning device as claimed in claim 1 is characterized in that, with the line pressure of 0.2N/cm to 1.2N/cm scope with described cleaning balde by being pressed on the described parts that are cleaned.

12. cleaning device as claimed in claim 11 is characterized in that, with the line pressure that is less than or equal to 0.9N/cm with described cleaning balde by being pressed on the described parts that are cleaned.

13. cleaning device as claimed in claim 1 is characterized in that, forms teat on described cleaning balde, the front end that prevents described cleaning balde described support unit of butt and described cleaning balde breaks away from when being pressed on the described parts that are cleaned.

14. cleaning device as claimed in claim 1 is characterized in that, pad adds strengthening part on the drift of described cleaning balde part, and the front end that prevents this cleaning balde is when being pressed on the described parts that are cleaned and described cleaning balde breaks away from.

15. cleaning device as claimed in claim 1 is characterized in that, as the material of described cleaning balde, uses JISA hardness for spending to the rubber of 80 degree from 60.

16. cleaning device as claimed in claim 1 is characterized in that, the elasticity recovery of described cleaning balde is formed 23 ℃ be less than or equal to 30%.

17. cleaning device as claimed in claim 1 is characterized in that, with described cleaning balde by the described front end knuckle line portion low-friction coefficientization that is pressed on the described parts that are cleaned.

18. cleaning device as claimed in claim 17 is characterized in that, the fluorine-type resin impregnation of described front end knuckle line portion is with its front end knuckle line portion low-friction coefficientization.

19. cleaning device as claimed in claim 1 is characterized in that, the sphericity of described toner is formed more than or equal to 0.95.

20. a handle box is characterized in that, has cleaning device and image carrier integratedly, with respect to image processing system dismounting freely,

Described cleaning device will be pressed on the parts that are cleaned that move on the surface round about by the front end knuckle line portion of the flexible cleaning scraper plate of support unit supporting, remove the lip-deep toner of these parts that are cleaned, wherein, the angle of the formation front end knuckle line portion of described cleaning balde is formed the obtuse angle, and, be made as t1 at thickness with the component crimping part that is cleaned with described cleaning balde, when the drift of described cleaning balde is made as t3, form the relation of 1.75≤t3/t1≤3, the described parts that are cleaned are image carrier, by the remaining toner that still remains in after the transfer printing of described cleaning balde removal image on this image carrier.

21. handle box as claimed in claim 20 is characterized in that, to press more than or equal to the face of 2.0MPa described front end knuckle line portion by being pressed on the described parts that are cleaned.

22. image processing system, it is characterized in that, has such cleaning device, it will be pressed on the parts that are cleaned that move on the surface round about by the front end knuckle line portion of the flexible cleaning scraper plate of support unit supporting, remove the lip-deep toner of these parts that are cleaned, wherein, the angle of the formation front end knuckle line portion of described cleaning balde is formed the obtuse angle, and, be made as t1 at thickness with the component crimping part that is cleaned with described cleaning balde, when the drift of described cleaning balde is made as t3, form the relation of 1.75≤t3/t1≤3, the described parts that are cleaned are image carrier, by the remaining toner that still remains in after the transfer printing of described cleaning balde removal image on this image carrier.

23. image processing system as claimed in claim 22 is characterized in that, to press more than or equal to the face of 2.0MPa described front end knuckle line portion by being pressed on the described parts that are cleaned.

24. image processing system as claimed in claim 22 is characterized in that, the protective seam that contains inorganic fine particles is set on described image carrier.

25. image processing system as claimed in claim 22 is characterized in that, has the binder resin of band cross-linked structure on the protective seam of described image carrier.

26. image processing system as claimed in claim 25 is characterized in that, has electric charge and transport layer in the structure of described binder resin.

27. a handle box is characterized in that, have cleaning device and on image carrier the coating lubricant lubricant applying apparatus,

Described cleaning device will be pressed on the parts that are cleaned that move on the surface round about by the front end knuckle line portion of the flexible cleaning scraper plate of support unit supporting, remove the lip-deep toner of these parts that are cleaned, wherein, the angle of the formation front end knuckle line portion of described cleaning balde is formed the obtuse angle, and, be made as t1 at thickness with the component crimping part that is cleaned with described cleaning balde, when the drift of described cleaning balde is made as t3, form the relation of 1.75≤t3/t1≤3, the described parts that are cleaned are image carrier, by the remaining toner that still remains in after the transfer printing of described cleaning balde removal image on this image carrier, this handle box can be with respect to the dismounting of image processing system subject freedom.

28. handle box as claimed in claim 27 is characterized in that, to press more than or equal to the face of 2.0MPa described front end knuckle line portion by being pressed on the described parts that are cleaned.

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