JP7494564B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming device.

Conventionally, in electrophotographic image forming devices, the cleaning process for removing residual toner after transfer involves contacting the edge of a cleaning blade with the image carrier to scrape off the toner.

Cleaning blades are required to have cleaning properties, i.e., the ability to scrape off toner, so rubber materials that have high adhesion to the image carrier are generally used. However, because this rubber material is elastic, if a large frictional force acts on the edge, a phenomenon known as curling can occur, which can cause cleaning problems. Therefore, for example, a cleaning blade has been proposed in which the corner edges at both ends in the width direction of the photoreceptor are removed to reduce the frictional force in these areas (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 7-104626

However, the cleaning blade disclosed in Patent Document 1 above has a problem in that uneven contact pressure occurs near the boundary (step) between the part where the corner edge has been removed and the part where the corner edge has not been removed, resulting in poor cleaning.

The present invention was made in consideration of the above problems, and aims to provide an image forming device that can suppress cleaning failures.

In order to solve the above problem, the invention described in claim 1 is:
An image forming apparatus having a cleaning blade for removing deposits from a surface of an image carrier,
The cleaning blade is
the cleaning blade is a rectangular elastic body, and an upstream surface of the cleaning blade facing the upstream side of the moving direction of the image carrier, the side opposite to the edge of the cleaning blade that comes into contact with the image carrier, is inclined upward in a direction away from the center in the longitudinal direction of the cleaning blade, so as to give a gradient to the upstream surface,
the edge is formed at an obtuse angle by beveling the upstream face ;
The edge formed at an obtuse angle has a ridgeline formed in a straight line, and is formed so that the degree of the obtuse angle continuously increases as it goes away from the center in the longitudinal direction.
It is characterized by:
The invention described in claim 2 is
An image forming apparatus having a cleaning blade for removing deposits from a surface of an image carrier,
The cleaning blade is
The cleaning blade is a rectangular elastic body, and is formed so that the thickness of both ends increases with increasing distance from the center in the longitudinal direction of the cleaning blade.
an edge of the cleaning blade that comes into contact with the image carrier is chamfered from an upstream surface facing the upstream side of the moving direction of the image carrier at both ends to a downstream surface connected to the upstream surface via the edge, thereby forming an obtuse angle;
The edge formed at an obtuse angle has a ridgeline formed in a straight line, and is formed so that the degree of the obtuse angle continuously increases as it goes away from the center in the longitudinal direction.
It is characterized by:

The present invention relates to an image forming apparatus comprising :
a lubricant application mechanism for applying a lubricant to a surface of the image carrier;
the cleaning blade has edges at the obtuse angle in a region facing both ends of the image carrier where the lubricant is not applied;
It is characterized by:

The invention described in claim 4 is the image forming apparatus described in any one of claims 1 to 3 ,
The image bearing member has a surface protective layer on a charge transport layer.
It is characterized by:

The invention described in claim 5 is the image forming apparatus described in any one of claims 1 to 4 ,
the cleaning blade has an edge formed at an obtuse angle by a surface on an upstream side in a moving direction of the image carrier and a surface adjacent to the upstream surface;
It is characterized by:

The present invention relates to an image forming apparatus comprising:
the cleaning blade is disposed in a counter-contact manner with the surface of the image carrier, facing in a direction opposite to the moving direction of the image carrier;
It is characterized by:

The present invention makes it possible to suppress cleaning failures.

FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus. 2 is a schematic cross-sectional view illustrating a photoconductor drum, a charging unit, a developing unit, and a cleaning unit in an image forming unit. FIG. 4 is a diagram showing the relationship in the longitudinal direction between the cleaning blade and the brush roller and solid lubricant constituting the lubricant application mechanism. FIG. FIG. 2A is a front view showing one end of a cleaning blade (Example 1), and FIG. 2B is a perspective view showing the one end. 4(b) is a diagram showing the contact state with the photosensitive drum at the X1 cross section in FIG. 4(b), FIG. 4(b) is a diagram showing the contact state with the photosensitive drum at the Y1 cross section in FIG. 4(b), and FIG. 4(c) is a diagram showing the contact state with the photosensitive drum at the Z1 cross section in FIG. 4(b). 1A is a front view showing one end of a cleaning blade of Modification 1 (Example 2), and FIG. 1B is a perspective view showing the one end. 6(b) is a diagram showing the contact state with the photosensitive drum at the X2 cross section in FIG. 6(b), (b) is a diagram showing the contact state with the photosensitive drum at the Y2 cross section in FIG. 6(b), and (c) is a diagram showing the contact state with the photosensitive drum at the Z2 cross section in FIG. 6(b). 1A is a front view showing one end of a cleaning blade of Modification 2 (Example 3), and FIG. 1B is a perspective view showing the one end. FIG. 2A is a front view showing one end of a cleaning blade (Comparative Example 1), and FIG. 2B is a perspective view showing the one end. FIG. 4A is a front view showing one end of a cleaning blade (Comparative Example 2), and FIG. 4B is a perspective view showing the one end. 10(b) is a diagram showing the contact state with the photosensitive drum at the X3 cross section in FIG. 10(b), FIG. 10(b) is a diagram showing the contact state with the photosensitive drum at the Y3 cross section in FIG. 10(b), and FIG. 10(c) is a diagram showing the contact state with the photosensitive drum at the Z3 cross section in FIG. 10(b). FIG. 4A is a front view showing one end of a cleaning blade (Comparative Example 3), and FIG. 4B is a perspective view showing the one end. 5 is a graph showing the distribution of contact pressure of a cleaning blade against a photosensitive drum in the longitudinal direction. 4 is a graph showing the amount of toner reaching the cleaning blade in the longitudinal direction. 1 is a graph showing the distribution of the amount of toner that has passed through the cleaning blade (the amount of toner that has passed through) in the longitudinal direction. 4 is a graph showing the contact position of the blade edge with respect to the photosensitive drum.

The following describes in detail the embodiments of the present invention with reference to the drawings.

Figure 1 shows the schematic configuration of an image forming device according to the present invention.

The image forming device 10 is configured with an automatic document transport unit 1, a scanner unit 2, an image forming unit 20, a paper feed unit 3, etc.

The automatic document feeder 1 feeds documents D placed on a document tray one by one along a predetermined feed path.
The scanner unit 2 irradiates a light source onto the transported document D and receives light reflected from the document D. The scanner unit 2 converts the received optical signal into an electrical signal (image data) and outputs the converted image data to the image forming unit 20.

The image forming unit 20 is arranged with four sets of image forming units 20Y, 20M, 20C, and 20K that form images of the colors yellow (Y), magenta (M), cyan (C), and black (K). A toner image of each color is formed on the photoconductor drum 11 corresponding to each color based on image data, and a color image is formed by transferring and superimposing the toner images of each color onto the intermediate transfer belt 16 by the primary transfer unit 13. A series of image forming operations is performed until the primarily transferred color image is secondarily transferred to the recording material P and fixed.

The configuration and operation of the photoconductor drum 11 and its surroundings will be briefly described.
In this case, the image forming unit 20Y for yellow (Y) color will be described, and the configurations for other colors are similar to that for yellow (Y), so descriptions thereof will be omitted.
The charging section 23Y uniformly charges the surface of the photoconductor drum 11Y.
The exposure section 22Y exposes the area on the surface of the photoconductor drum 11Y to which toner is to be attached, and removes the charge from the exposed area to form an electrostatic latent image.
The developing unit 21Y develops a toner image by attaching toner to the electrostatic latent image on the photoconductor drum 11Y.
The primary transfer unit 13Y transfers the toner image developed on the photoconductor drum 11Y onto the intermediate transfer belt 16 by applying a bias voltage of a polarity opposite to that of the toner.
The cleaning section 25Y removes residual toner that has not been transferred to the intermediate transfer belt 16 and remains on the photoconductor drum 11Y using a blade or the like.

The intermediate transfer belt 16 is an endless belt that is stretched over multiple rollers and supported so that it can run. The toner images of each color formed in the image forming units 20Y, 20M, 20C, and 20K are transferred sequentially onto the running intermediate transfer belt 16 by the primary transfer units 13Y, 13M, 13C, and 13K, and a color image (toner image) in which layers of each color (Y, M, C, K) are superimposed is formed on the intermediate transfer belt 16.

The secondary transfer roller 13A is disposed in contact with the secondary transfer opposing roller 16a via the intermediate transfer belt 16, and the toner image on the intermediate transfer belt 16 is secondarily transferred to the recording material P as the recording material P passes through the transfer nip formed between the secondary transfer roller 13A and the secondary transfer opposing roller 16a.

A fixing device 5 is disposed on the discharge side of the recording material P of the secondary transfer roller 13A, which clamps and transports the toner image formed on the conveyed recording material P and fixes the toner image to the recording material P.

The paper feed unit 3 stores recording material P in multiple trays and feeds the recording material P to the image forming unit 20 via a specified transport path.

Each of the above components of the image forming device 10 is connected to the control unit S and is appropriately controlled by the control unit S.

Figure 2 is a schematic cross-sectional view illustrating the photoconductor drum, charging unit, developing unit, and cleaning unit in the image forming unit.

The charging section 23 uniformly charges the entire surface of the photoconductor drum 11. Here, the photoconductor drum 11 has a surface protection layer on the surface of a photosensitive layer composed of a charge generation layer and a charge transport layer.

The developing unit 21 is equipped with a developing roller 26 and an agitating screw 27 that agitates the developer, inside a developing unit casing 36 that contains a developer consisting of toner and carrier with external additives added to reduce fluidity and adhesion. The developing roller 26 is located opposite the photoconductor drum 11 and is arranged to be rotatable in the direction of arrow B with a predetermined gap (hereinafter referred to as the developing gap) between the photoconductor drum 11. The developing gap is set to, for example, about 0.2 to 0.5 mm. The rotational operation of the developing roller 26 is controlled by the control unit S.

The cleaning section 25 is equipped with a cleaning blade 28, a lubricant application mechanism 29, and a smoothing blade 30.

The cleaning blade 28 is made of an elastic material such as urethane and has a rectangular shape with a thickness of 1.8 mm. It is attached to the support member 31a that supports the cleaning blade 28 with an adhesive or the like so that the free length of the blade is a predetermined length. The cleaning blade 28 is arranged to abut in a counter direction to the rotation direction of the photoreceptor drum 11 in order to scrape off any residue remaining on the surface of the photoreceptor drum 11 after transfer.

The lubricant application mechanism 29 includes a brush roller 32 , a solid lubricant 33 , and a pressure member 34 , and is provided downstream of the cleaning blade 28 in the rotation direction of the photoconductor drum 11 .
Brush roller 32 is provided so as to come into contact with the surface of photoreceptor drum 11 and solid lubricant 33. Solid lubricant 33 is scraped off by rotation of brush roller 32, and the scraped off lubricant adheres to brush roller 32. Then, the lubricant adhered to brush roller 32 adheres to the surface of photoreceptor drum 11 at the contact portion with photoreceptor drum 11.

The brush roller 32 is made of a resin brush, such as an acrylic material. The bristles of the brush have a certain degree of hardness in order to scrape off the solid lubricant 33, but at the same time, the bristles are hard enough not to damage the surface of the photoconductor drum 11. The brush roller 32 is connected to a motor and rotates in a counter direction to the rotation direction of the photoconductor drum 11, as indicated by the arrow A. The control unit S controls the rotation operation, and the amount of lubricant supplied to the photoconductor drum 11 is increased or decreased by varying the rotation speed of the brush roller 32, thereby controlling the rotation so that a predetermined amount is supplied. The rotation direction of the brush roller 32 may be the opposite direction to the arrow A, but the arrow A (counter direction) is preferable, as it is more efficient at scraping off the lubricant and attaching it to the photoconductor drum 11.

The solid lubricant 33 is made of fatty acid metal salts such as zinc stearate (ZnSt) and is formed into a rectangular parallelepiped shape extending in the direction of the rotation axis of the photoreceptor drum 11. The solid lubricant 33 is held by a holding member 33a and is pressed against the brush roller 32 via the holding member 33a by a pressure member 34 such as a spring arranged inside the casing 35 of the cleaning unit 25.

The smoothing blade 30 is provided so as to abut in the trailing direction downstream of the lubricant application mechanism 29, and has the function of spreading the lubricant applied to the photoconductor drum 11 by the lubricant application mechanism 29 to form a uniform thin film on the surface of the photoconductor drum 11. The smoothing blade 30 is made of an elastic material such as urethane, and is attached with an adhesive or the like to the support member 31b that supports the smoothing blade 30 so that the free length of the blade is a predetermined length.

The cleaning blade 28 is explained in detail below with reference to Figures 3 to 5.

FIG. 3 is a diagram showing the relationship in the longitudinal direction between the cleaning blade 28 and the solid lubricant (lubricant bar) 33 constituting the lubricant application mechanism 29. As shown in FIG.
As shown in FIG. 3, the cleaning blade 28 is designed to be longer than the solid lubricant 33 in the longitudinal direction. If the solid lubricant 33 is longer than the cleaning blade 28, a large amount of lubricant will adhere to the blade end seal 37, causing the toner to slip through. Here, the blade end seal 37 is intended to prevent the toner and the like from leaking out to the outside of the cleaning blade 28 (a position where the cleaning blade 28 cannot scrape off foreign matter). However, by designing the cleaning blade 28 to be longer than the solid lubricant 33, the cleaning blade 28 will come into contact with the portion where the lubricant is not applied. As a result, at both ends of the cleaning blade 28 where the lubricant is not applied, the frictional force generated between the photosensitive drum 11 and the cleaning blade 28 becomes large, and curling is likely to occur. Therefore, in the cleaning blade 28 of this embodiment, the blade edges BE at both ends are formed at an obtuse angle, and the degree of the obtuse angle is continuously increased as it moves away from the center in the longitudinal direction, thereby suppressing the occurrence of curling.
The brush roller 32 is designed to be longer than the solid lubricant 33 and shorter than the cleaning blade 28 .

FIG. 4A is a front view showing one end of the cleaning blade 28, and FIG. 4B is a perspective view showing the one end.
4(a) and 4(b), the cleaning blade 28 has a blade edge BE that contacts the photosensitive drum 11 at one end, which is formed at an obtuse angle. Specifically, the blade edge BE that is formed at this obtuse angle is formed so that the degree of the obtuse angle continuously increases as it moves away from the center in the longitudinal direction of the cleaning blade 28, that is, toward the end of the cleaning blade 28. More specifically, the cleaning blade 28 is formed so that the ridgeline of the blade edge BE is inclined downward in the direction away from the center in the longitudinal direction of the cleaning blade 28, and an inclination is given to the upstream surface 28a, thereby forming the degree of the obtuse angle continuously increasing.
Although not shown in the figure, the cleaning blade 28 also has, at the other end, the blade edge BE that abuts against the photosensitive drum 11 formed at an obtuse angle, similar to the above-mentioned one end, and this blade edge BE formed at an obtuse angle is formed so that the degree of the obtuse angle continuously increases as it moves away from the center in the longitudinal direction of the cleaning blade 28.

The cleaning blade 28 has an obtuse angled blade edge BE in the areas facing both ends of the photoconductor drum 11 where no lubricant is applied, i.e., the areas not facing the solid lubricant 33 (see FIG. 3). The cleaning blade 28 has an obtuse angled blade edge BE in the areas other than both ends (non-ends).

Figure 5(a) is a diagram showing the contact state with the photoconductor drum 11 at the X1 cross section in Figure 4(b), Figure 5(b) is a diagram showing the contact state with the photoconductor drum 11 at the Y1 cross section in Figure 4(b), and Figure 5(c) is a diagram showing the contact state with the photoconductor drum 11 at the Z1 cross section in Figure 4(b).

As shown in Figures 5(a) and 5(c), when the cleaning blade 28 cleans the toner, the force F acts on the toner particles in a direction perpendicular to the surface that contacts the cleaning blade 28. At this time, the component force Fx of the force F, i.e., the force that prevents the toner from passing through (the force that prevents the toner from passing through) is smaller at the portion where the blade edge BE has an obtuse angle (e.g., the Z section) than at the portion where the blade edge BE has an angle of 90 degrees (e.g., the X section). This is because the supply of lubricant and toner is insufficient at the portions of the cleaning blade 28 that do not face the solid lubricant 33 or the development range (see Figure 3), i.e., at both ends of the cleaning blade 28, the lubricant and toner particles cannot function sufficiently as rollers between the cleaning blade 28 and the photosensitive drum 11, and if the force that prevents the toner from passing through (Fx) is large, the frictional force acting on the cleaning blade 28 becomes large, causing the blade to turn over. On the other hand, at the portion of the cleaning blade 28 that faces the solid lubricant 33 and the development range, i.e., the non-end portion of the cleaning blade 28, the toner is sufficiently supplied, so even if the angle of the blade edge BE is set to 90 degrees and the slip-through prevention force (Fx) is increased, the lubricant, toner, and other particles can function sufficiently as rollers between the cleaning blade 28 and the photosensitive drum 11, so the frictional force acting on the cleaning blade 28 is small and curling does not occur.

However, for example, as shown in FIG. 10(a) and FIG. 10(b), if both ends of the cleaning blade CB2 are discontinuous and obtuse, the amount of penetration of the cleaning blade CB2 into the photoconductor drum 11, i.e., the contact pressure, becomes smaller at the Y3 cross section than at the X3 cross section and Z3 cross section, as shown in FIG. 11(a) to FIG. 11(c). Therefore, with this cleaning blade CB2, the contact pressure becomes uneven at both ends, making it easier for toner to slip through. Here, FIG. 11(a) is a diagram showing the contact state with the photoconductor drum 11 at the X3 cross section in FIG. 10(b), FIG. 11(b) is a diagram showing the contact state with the photoconductor drum 11 at the Y3 cross section in FIG. 10(b), and FIG. 11(c) is a diagram showing the contact state with the photoconductor drum 11 at the Z3 cross section in FIG. 10(b).

Therefore, in the cleaning blade 28 of this embodiment, as described above, the blade edge BE is formed so that the degree of obtuseness increases continuously in the longitudinal direction of the cleaning blade 28 as it moves away from the center, that is, toward the end of the cleaning blade 28. As shown in Figures 5(a) to (c), the amount of penetration of the cleaning blade 28 into the photosensitive drum 11, i.e., the contact pressure, gradually decreases as it moves away from the center in the longitudinal direction of the cleaning blade 28, from the X1 cross section to the Y1 cross section to the Z1 cross section. As a result, in the cleaning blade 28 of this embodiment, unlike the above-mentioned cleaning blade CB2 (see Figure 10), the contact pressure does not change significantly, making it possible to suppress toner slipping through.

The cleaning blade 28 may have any shape as long as the contact pressure at the blade edges BE at both ends does not change significantly. For example, the cleaning blade 128 of modified example 1 or the cleaning blade 228 of modified example 2 described below may be used.

FIG. 6A is a front view showing one end of a cleaning blade 128 of the first modified example, and FIG. 6B is a perspective view showing the one end.
6(a) and 6(b), the cleaning blade 128 has a blade edge BE that contacts the photosensitive drum 11 at one end, which is formed at an obtuse angle. Specifically, the blade edge BE formed at this obtuse angle is formed so that the degree of the obtuse angle continuously increases as it moves away from the center in the longitudinal direction of the cleaning blade 128, that is, toward the end of the cleaning blade 128. More specifically, the cleaning blade 128 is formed so that the ridgeline of the blade edge BE is kept straight, and the side 128a1 of the upstream surface 128a that faces the blade edge BE is inclined upward in the direction away from the center in the longitudinal direction of the cleaning blade 128, thereby giving a gradient to the upstream surface 128a, so that the degree of the obtuse angle continuously increases.
Although not shown in the figure, the cleaning blade 128 also has, at the other end, the blade edge BE that abuts against the photosensitive drum 11 formed at an obtuse angle, similar to the above-mentioned one end, and this blade edge BE formed at an obtuse angle is formed such that the degree of obtuse angle continuously increases as it moves away from the center in the longitudinal direction of the cleaning blade 128.

Figure 7(a) is a diagram showing the contact state with the photoconductor drum 11 at the X2 cross section in Figure 6(b), (b) is a diagram showing the contact state with the photoconductor drum 11 at the Y2 cross section in Figure 6(b), and (c) is a diagram showing the contact state with the photoconductor drum 11 at the Z2 cross section in Figure 6(b).

As shown in Figures 7(a) to 7(c), in the cleaning blade 128 of variant 1, the amount of penetration of the cleaning blade 128 into the photoconductor drum 11 is uniform at each of the X2 cross section, the Y2 cross section, and the Z2 cross section. As a result, the contact pressure of the cleaning blade 128 is uniform at both ends, making it possible to more effectively prevent toner from slipping through.

FIG. 8A is a front view showing one end of a cleaning blade 228 of the second modified example, and FIG. 8B is a perspective view showing the one end.
8A and 8B, the cleaning blade 228 has a blade edge BE that contacts the photosensitive drum 11 at one end, which is formed at an obtuse angle. Specifically, the blade edge BE formed at this obtuse angle is formed so that the degree of the obtuse angle continuously increases as it moves away from the center in the longitudinal direction of the cleaning blade 228, that is, toward the end of the cleaning blade 228. More specifically, the cleaning blade 228 is formed so that the thickness of one end increases as it moves away from the center in the longitudinal direction, and the corners of the cleaning blade 228 are chamfered from the upstream surface 228a to the downstream surface 228b of the one end so that the ridge of the blade edge BE remains straight and the degree of the obtuse angle of the blade edge BE continuously increases.
Although not shown in the figure, the cleaning blade 228 also has, at the other end, the blade edge BE that abuts against the photosensitive drum 11 formed at an obtuse angle, similar to the above-mentioned one end, and this blade edge BE formed at an obtuse angle is formed such that the degree of obtuse angle continuously increases as it moves away from the center in the longitudinal direction of the cleaning blade 228.

Next, an Accurio Press C6100 manufactured by Konica Minolta was used as the image forming device 10, and evaluations of curling and toner slip-through were performed when the cleaning blade of this embodiment (Examples 1 to 3) was used, and when a cleaning blade that does not satisfy the conditions of this embodiment (Comparative Examples 1 to 3) was used.

The experimental procedure and evaluation method will be explained.
First, regarding the evaluation of curling, since curling is likely to occur in images with low coverage, the occurrence of curling was visually confirmed when printing with 0% coverage was repeated 1500 times on one sheet of paper (A4 size plain paper). As a result of the visual confirmation, those that curled were evaluated as "x", and those that did not curl were evaluated as "o". In addition, for those that curled, the number of printed sheets when curling occurred was also recorded.
In addition, with regard to the evaluation of curling, the evaluation was performed when a photosensitive drum having a photosensitive layer formed on the outermost surface was used as the photosensitive drum, and when a photosensitive drum having a protective layer (surface protective layer) was used.
The environment in this experiment was set to 30° C. and 80% RH.

Next, for the evaluation of toner slip-through, 60,000 sheets of A4-sized plain paper were printed with a vertical band image with a width of 10 mm and a coverage of 100%. After printing was completed, the presence or absence of toner slip-through was visually confirmed. As a result of visual confirmation, those that did not slip-through were evaluated as "◎". In addition, for those that could be confirmed to have slip-through, the length of the toner that slipped through was measured, and those that were less than 5 mm long and did not adhere to the brush roller (lubricant application brush) were evaluated as "◯", and those that were 5 mm long or longer and did adhere to the brush roller (lubricant application brush) were evaluated as "×". Here, the reason why those that were less than 5 mm long and did not adhere to the brush roller were evaluated as "◯" is that if toner adheres to the brush roller, the lubricant application performance on the image carrier is reduced and cleaning defects occur, but if the toner does not adhere to the brush roller, cleaning defects do not occur. In addition, for those that slip-through occurred, the length (mm) of the toner that slipped through was also recorded.
In addition, in order to evaluate the toner slip-through, similar to the evaluation of curling, the evaluation was performed when a photosensitive drum having a photosensitive layer formed on the outermost surface was used as the photosensitive drum, and when a photosensitive drum having a protective layer (surface protective layer) was used.
The environment in this experiment was set to 10° C. and 20% RH.

Next, the cleaning blades of Examples 1 to 3 will be described.
Example 1 is the cleaning blade 28 (see FIG. 4) of this embodiment.
The second embodiment is the cleaning blade 128 of the first modified example (see FIG. 6).
The third embodiment is the cleaning blade 228 of the second modified example (see FIG. 8).

Next, the cleaning blades of Comparative Examples 1 to 3 will be described.
9(a) and 9(b), Comparative Example 1 is a cleaning blade CB1 having a rectangular parallelepiped flat plate shape, where Fig. 9(a) is a front view showing one end of the cleaning blade CB1, and Fig. 9(b) is a perspective view showing the one end.
Comparative Example 2 is the above-mentioned cleaning blade CB2 (see FIG. 10).

Comparative Example 3 is a cleaning blade CB3 in which the upstream surface CB3a inclines upward in the longitudinal direction of the blade as it moves away from the center, as shown in Figures 12(a) and 12(b). Here, Figure 12(a) is a front view showing one end of the cleaning blade CB3, and Figure 12(b) is a perspective view showing that end.

As shown in Table I, the results of the evaluation of curling showed that in Examples 1 to 3, curling did not occur either in the case where a photosensitive drum having a photosensitive layer formed on the outermost surface was used or in the case where a photosensitive drum having a protective layer was used.
On the other hand, in Comparative Examples 1 to 3, in both cases where a photoconductor drum having a photosensitive layer formed on the outermost surface was used and where a photoconductor drum having a protective layer formed was used, curling did not occur in Comparative Example 2 and Comparative Example 3, but curling occurred in Comparative Example 1. In Comparative Example 1, when a photoconductor drum having a photosensitive layer formed on the outermost surface was used, the number of sheets on which curling occurred was 21, and when a photoconductor drum having a protective layer was used, the number of sheets on which curling occurred was 0.

As shown in Table I, in the results of the evaluation of toner slip-through, in Example 1, when a photoconductor drum having a photosensitive layer formed on the outermost surface was used, the slip-through length was 0.5 mm, and only slight slip-through occurred, and the slip-through was evaluated as "good," whereas when a photoconductor drum having a protective layer was used, no slip-through occurred, and the evaluation was "good." In Examples 2 and 3, in both cases where a photoconductor drum having a photosensitive layer formed on the outermost surface and a photoconductor drum having a protective layer were used, no slip-through occurred, and the evaluation was "good."
On the other hand, in Comparative Examples 1 to 3, in both cases where a photosensitive drum having a photosensitive layer formed on the outermost surface was used and where a photosensitive drum having a protective layer was used, no slip-through occurred in Comparative Example 1, and the evaluation for this was "◎". However, in Comparative Examples 2 and 3, slip-through with a length exceeding 14 mm occurred, and the evaluation for this was "×".

Figure 13 is a graph showing the distribution of the contact pressure of the cleaning blade against the photosensitive drum in the longitudinal direction. This graph shows the results of measuring the contact pressure (linear pressure) at one end of the cleaning blade in the image forming apparatuses to which Examples 1 to 3 and Comparative Examples 1 to 3 are respectively applied, using a surface pressure distribution measuring device. The contact pressure was calculated by integrating the values in the FD direction. The positions X, Y, and Z shown on the horizontal axis of the graph correspond to the respective locations of the X1, Y1, and Z1 cross sections of the cleaning blade 28 in Example 1 (see Figure 4(b)), the respective locations of the X2, Y2, and Z2 cross sections of the cleaning blade 128 in Example 2 (see Figure 6(b)), and the respective locations of the X3, Y3, and Z3 cross sections of the cleaning blade CB2 in Comparative Example 2 (see Figure 10(b)) (similar to Figures 14 and 15).

As shown in FIG. 13, in Example 1, at one end where the blade edge BE is formed at an obtuse angle, the contact pressure gradually decreases as it moves away from the center in the longitudinal direction. In Examples 2 and 3, as described above, the ridge of the blade edge BE is a straight line, so the contact pressure does not decrease and is constant even at the one end where the blade edge BE is formed at an obtuse angle. In Comparative Example 1, the angle of the blade edge BE is uniformly 90 degrees, so the contact pressure is also constant. In Comparative Example 2, the contact pressure decreases at the step portion (near position Y) that is the boundary between the one end where the blade edge BE is formed at an obtuse angle and the non-end where the blade edge BE is not formed at an obtuse angle. In Comparative Example 3, as described above, the upstream surface in the longitudinal direction of the blade has an upwardly inclined shape as it moves away from the center, so the contact pressure gradually increases as it moves away from the center in the longitudinal direction.

14 is a graph showing the amount of toner reaching the cleaning blade in the longitudinal direction. Note that a lattice-shaped toner receiver was placed vertically below the cleaning blade, and the amount of toner that was cleaned by the cleaning blade and fell into the toner receiver was measured as the amount of toner reaching the cleaning blade.
14, in the region facing the development range (see FIG. 3) in the longitudinal direction, that is, the region inside position Y, the amount of toner that reaches is large because transfer residual toner and fog toner reach that region. On the other hand, in the region from position Y to position Z, only toner that has been cleaned and scattered in the region inside position Y reaches that region, so in that region, the amount of toner that reaches gradually decreases with increasing distance from the longitudinal center.

Figure 15 is a graph showing the distribution of the amount of toner that has slipped through the cleaning blade in the longitudinal direction (slipped amount). This graph shows the results of measuring the amount of toner when the brush roller installed downstream of the cleaning blade (Examples 1 to 3 and Comparative Examples 1 to 3) was grounded to GND and the toner that had slipped through the cleaning blade was attracted by the brush roller. In order to measure the longitudinal distribution, the measurement area was divided in the longitudinal direction, and the filter and hose were connected to the suction pump in that order, and the slipped amount was measured based on the weight difference of the filter part before and after suction.

As shown in FIG. 15, in Example 1, at one end where the blade edge BE is formed at an obtuse angle, the amount of slipping through gradually increases as it moves away from the center in the longitudinal direction. This is thought to be due to the fact that, as shown in the graph of FIG. 13, in Example 1, at one end where the blade edge BE is formed at an obtuse angle, the contact pressure gradually decreases as it moves away from the center in the longitudinal direction. In Examples 2 and 3, even at one end where the blade edge BE is formed at an obtuse angle, the amount of slipping through does not increase and is constant. This is thought to be due to the ridge of the blade edge BE being a straight line, as described above. In Comparative Example 1, since the contact pressure is constant in the longitudinal direction, the amount of slipping through is also constant, and in the area outside the development range (see FIG. 3), i.e., the area outside position Y, only the toner that has been cleaned and scattered in the area inside position Y reaches the area, so in that area, the amount of slipping through gradually decreases as it moves away from the center in the longitudinal direction. In Comparative Example 2, the amount of slipping through increases at the step (near position Y) which is the boundary between one end where the blade edge BE is formed at an obtuse angle and the non-end where the blade edge BE is not formed at an obtuse angle. This is thought to be due to the fact that the contact pressure at the step decreases in Comparative Example 2, as shown in the graph of FIG. 13. In Comparative Example 3, the amount of slipping through gradually increases in the area outside position Y. This is thought to be because, as described above, in Comparative Example 3, the upstream surface in the longitudinal direction of the blade has an upwardly inclined shape as it moves away from the center, so the blade edge BE gradually rises as it moves away from the center. Note that the "toner accumulation" line in the graph of FIG. 15 represents a threshold value, and toner accumulation occurs when the amount of slipping through is greater than this "toner accumulation" line. The "turning" line also represents a threshold value, and turning occurs when the amount of slipping through is less than this "turning" line.

FIG. 16 is a graph showing the contact position of the blade edge BE with respect to the photosensitive drum.
As shown in FIG. 16, in Example 1, as the blade moves away from the center in the longitudinal direction, the ridge of the blade edge BE moves downward in the downstream direction (see FIG. 4(a)), so the position where the blade edge BE contacts the photosensitive drum moves downward. When cleaning the toner, the toner that collides with the cleaning blade bounces back to the upstream side in the photosensitive drum rotation direction due to the repulsive force when it collides with the cleaning blade, and repeats the reciprocating motion of colliding with the cleaning blade again. At that time, in the configuration in which the ridge moves downward in the downstream direction as in Example 1, the reciprocating toner also flows downstream, and a large amount of toner accumulates at the end of the cleaning blade, so the number of times the toner collides with the cleaning blade increases. When the number of toner collisions increases, toner collision occurs before the cleaning blade is restored, and it is considered that the toner slips through as shown in Table I. On the other hand, in Examples 2 and 3, the contact position (position of the ridge) does not change from the center to the end, so the toner does not move in the longitudinal direction and accumulate as in Example 1, and it is considered that the toner does not slip through as shown in Table I.

As described above, the cleaning blade 28 of the image forming device 10 according to this embodiment is a rectangular elastic body, and the blade edge BE is formed at an obtuse angle. The blade edge BE formed at an obtuse angle is formed so that the degree of the obtuse angle continuously increases as it moves away from the center in the longitudinal direction.
Therefore, according to the image forming apparatus 10 of this embodiment, the blade edge BE formed at an obtuse angle is formed so that the degree of the obtuse angle continuously increases with increasing distance from the center in the longitudinal direction, thereby making it possible to prevent unevenness in the contact pressure against the photosensitive drum 11. This makes it possible to prevent toner from slipping through between the cleaning blade 28 and the photosensitive drum 11, thereby making it possible to prevent cleaning defects.

In addition, the image forming apparatus 10 according to this embodiment is equipped with a lubricant application mechanism 29 that applies lubricant to the surface of the photosensitive drum 11, and the cleaning blade 28 has a blade edge BE formed at an obtuse angle in the area facing both ends of the photosensitive drum 11 where lubricant is not applied.
Therefore, according to the image forming apparatus 10 of this embodiment, the blade edge BE in the area facing both ends of the photosensitive drum 11 where no lubricant is applied, i.e., the area where the frictional force acting on the cleaning blade 28 becomes large, is formed at an obtuse angle, thereby suppressing the occurrence of curling.

In addition, the image forming device 10 according to this embodiment has a surface protection layer on the surface of the photosensitive drum 11, which can more effectively prevent curling and toner from slipping through when cleaning the residual toner after transfer with the cleaning blade 28.

In addition, according to the cleaning blade 28 of the image forming device 10 of this embodiment, the blade edge BE is formed at the above-mentioned obtuse angle by the upstream surface in the movement direction (rotation direction) of the photosensitive drum 11 and the downstream surface (downstream surface) adjacent to that surface, so that curling can be more effectively suppressed.

In addition, the cleaning blade 28 of the image forming apparatus 10 according to this embodiment is in contact with the surface of the photosensitive drum 11 by a counter method in which the cleaning blade 28 is arranged in the opposite direction to the movement direction (rotation direction) of the photosensitive drum 11.
Therefore, according to the image forming apparatus 10 of this embodiment, even when the counter method in which curling is likely to occur is adopted, it is possible to suppress the occurrence of curling.

The above is a detailed explanation based on an embodiment of the present invention, but the present invention is not limited to the above embodiment and can be modified without departing from the gist of the invention.

For example, in the above embodiment, a photosensitive drum is used as an example of an image carrier, but a transfer belt may be used as the image carrier.
In addition, the detailed configurations and operations of each device constituting the image forming apparatus may be modified as appropriate without departing from the spirit and scope of the present invention.

10 Image forming apparatus 11 Photoconductor drum (image carrier)
21 developing section 23 charging section 25 cleaning section 28 cleaning blade (Example 1)
29 Lubricant application mechanism 32 Brush roller 33 Solid lubricant 128 Cleaning blade (Example 2)
228 Cleaning blade (Example 3)
BE Blade Edge

Claims (6)

An image forming apparatus having a cleaning blade for removing deposits from a surface of an image carrier,
The cleaning blade is
the cleaning blade is a rectangular elastic body, and an upstream surface of the cleaning blade facing the upstream side of the moving direction of the image carrier, the side opposite to the edge of the cleaning blade that comes into contact with the image carrier, is inclined upward in a direction away from the center in the longitudinal direction of the cleaning blade, so as to give a gradient to the upstream surface,
the edge is formed at an obtuse angle by beveling the upstream face ;
The edge formed at an obtuse angle has a ridgeline formed in a straight line, and is formed so that the degree of the obtuse angle continuously increases as it goes away from the center in the longitudinal direction.
1. An image forming apparatus comprising: An image forming apparatus having a cleaning blade for removing deposits from a surface of an image carrier,
The cleaning blade is
The cleaning blade is a rectangular elastic body, and is formed so that the thickness of both ends increases with increasing distance from the center in the longitudinal direction of the cleaning blade.
an edge of the cleaning blade that comes into contact with the image carrier is chamfered from an upstream surface facing the upstream side of the moving direction of the image carrier at both ends to a downstream surface connected to the upstream surface via the edge, thereby forming an obtuse angle;
The edge formed at an obtuse angle has a ridgeline formed in a straight line, and is formed so that the degree of the obtuse angle continuously increases as it goes away from the center in the longitudinal direction.
1. An image forming apparatus comprising: a lubricant application mechanism for applying a lubricant to a surface of the image carrier;
the cleaning blade has edges at the obtuse angle in a region facing both ends of the image carrier where the lubricant is not applied;
3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-color image forming apparatus. The image bearing member has a surface protective layer on a charge transport layer.
4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction . the cleaning blade has an edge formed at an obtuse angle by a surface on an upstream side in a moving direction of the image carrier and a surface adjacent to the upstream surface;
5. The image forming apparatus according to claim 1 , wherein the image forming apparatus is a multi-color image forming apparatus. the cleaning blade is disposed in a counter-contact manner with the surface of the image carrier, facing in a direction opposite to the moving direction of the image carrier;
6. The image forming apparatus according to claim 1, wherein the image forming apparatus is a multi-layered image forming apparatus.

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