Developing roll, method for manufacturing the same, and printing device

The present invention is used in a printing device using toner such as a copying machine, a laser printer, and a facsimile.<u style="single">Develop roll and printing device using it</u>It is about.

Printing devices that use toner, such as laser printers, are required to have higher speeds or higher quality print quality. In order to meet these market needs, the developing rolls that supply toner of each color to the photosensitive drums that make up the laser printer have a smaller diameter that corresponds to the miniaturization of the printer, and the amount of toner that can be transported per unit time has increased. Alternatively, the uniformity of toner supply is required.

Therefore, the developing roll is required to supply toner to the photosensitive drum with a smaller diameter and higher rotation speed. Therefore, in order to make the printer compatible with high-speed printing, the developing roll side is required to increase the transport amount per unit time and stabilize it. Here, the developing roll is a columnar metal, and a developing roll is formed by inserting a rod-shaped magnet or the like inside the column.

Next, the conventional developing roll will be described with reference to FIGS. 11 and 12.

FIG. 11 (A) is a perspective view showing an example of the developing roll proposed in Patent Document 1, and FIG. 11 (B) is a perspective view showing an example of the developing roll proposed in Patent Document 2. In FIG. 11A, a cutting mark 2 extending in the longitudinal direction is formed on the surface of the developing roll 1a. In this way, in the case of the developing roll 1a shown in FIG. 11A, the surface of the developing roll 1a is cut so as to provide a cutting groove 2 in the longitudinal direction, thereby reducing the fluctuation of the developing roll 1a.

In FIG. 11B, a processing groove 4 extending in the circumferential direction of the developing roll 1b is formed on the surface of the developing roll 1b. In the case of the developing roll 1b shown in FIG. 11B, by providing irregularities in the circumferential direction of the developing roll 1b, uneven charging occurs due to the hit of the brush when the magnetic brush charging method is used as the charging device. To prevent that.

A columnar magnet member or the like is inserted into the cavity 3 in FIGS. 11 (A) and 11 (B), but these are not shown.

FIG. 12 is a cross-sectional view showing a part of the developing roll 1 proposed in Patent Document 3. In FIG. 12, the top 5 and the recess 6 are formed on the surface of the developing roll 1. The surface of the top 5 is formed with secondary fine irregularities 7a, and the surface of the recess 6 is formed with secondary fine irregularities 7b.

In FIG. 12, the developing roll 1 is formed by forming a resist pattern on an aluminum cylinder and etching it with caustic soda. The recessed portion 6 in the developing roll 1 is a portion not protected by the resist pattern, and corresponds to a portion in which aluminum is concavely removed by caustic soda. The top 5 corresponds to a portion protected by a resist pattern and not etched.

After forming the top 5 and the recess 6 on the surface of the developing roll 1 in FIG. 12, sandblasting is further performed on the surface, and after this sandblasting, the top is polished with a buff. is there. By performing sandblasting on the developing roll 1 on which the top 5 and the recess 6 are formed in this way, uniform unevenness can be formed on the entire surface of the developing roll 1. Also, by buffing or the like (or by selectively polishing the top 5), the secondary fine unevenness 7a of the top 5 is better than the secondary fine unevenness 7b provided in the recess 6. By reducing the size, the influence on the fusion of low melting point toner, the blotch, and the transport force before and after durability is reduced.

As described above, in the conventional developing roll 1, fine irregularities (for example, secondary fine irregularities 7a and 7b in FIG. 12) are formed by sandblasting.

Next, with reference to FIG. 13, the relationship between the secondary fine unevenness 7 provided in the recess 6 by sandblasting and the toner particle size will be described.

FIG. 13 is a cross-sectional view illustrating how the toner particles slip on the secondary fine irregularities 7 provided in the recessed portion 6. FIG. 13 is an enlarged cross-sectional view of the inner wall portion (for example, the bottom surface and the side surface) of the recessed portion 6. As shown in FIG. 13, a secondary fine unevenness 7b is formed on the inner wall portion of the recessed portion 6.

However, the secondary fine unevenness 7b is also an order of magnitude larger than the particle size of the toner 8. As described above, the size of the secondary fine unevenness 7b on a plane is 100 microns or more, which is an order of magnitude larger than the particle size of the toner 8 (for example, the primary particle size is about 4 microns). Therefore, the anti-slip effect cannot be obtained with the secondary fine unevenness 7b formed by sandblasting. That is, even if the unevenness 7b is secondarily fine, it is very large with respect to the toner 8, so that it is difficult to obtain the anchor effect (or the catching effect). Toner 8 easily slips on the inner wall surface).<patcit num="1"><text>Japanese Unexamined Patent Publication No. 5-158349</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2006-317684</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 11-133728</text></patcit>

<p> However, with the conventional developing roll 1, there are still problems in increasing the amount of toner that can be conveyed per unit time, and further in the uniformity at the time of high-speed printing required by the toner supply market.</p><p> For example, in the case shown in FIGS. 11A and 11B, the amount of toner that can be retained on the surfaces of the developing rolls 1a and 1b depends on the processing accuracy, and therefore may be easily affected by processing variations.</p><p> Further, in the case of FIG. 12, the toner is held in the recess 6, but when the toner particle size becomes as small as several microns as the print quality is improved, the toner slips in the recess 6. There was a case that it ended up. On the other hand, the unevenness formed by sandblasting has a size of 100 microns or more in the XY direction (for example, a plane or a circumferential direction) and a depth of several tens of microns in the Z direction (for example, a thickness direction). This is because the sandblasting process is performed by the collision of the abrasives ejected from the sandblasting device at high speed (for example, collision energy), and when the sandblasting material is made finer, the kinetic energy of the abrasives is extremely reduced. Its workability is reduced.</p><p> Therefore, the unevenness formed by sandblasting is more than an order of magnitude larger than the toner particle size, and the anti-slip effect cannot be obtained. That is, as shown in FIG. 13, the toner particles slip on the uneven surface formed by sandblasting.</p><p> Further, the sandblasting process causes fine scratches on the surface of the developing roll, which causes toner adhesion. Then, the toner adhering to the scratches cannot be collected in a toner box or the like, which causes stains.</p><p> In this way, when the developing roll 1 created by using the conventional sandblast rotates at high speed, toner particles and the like slip on the surface, increasing the toner transfer amount per unit time and stabilizing the toner transfer amount. Or, the amount of toner supplied to the in-plane of the developing roll 1 (or in-plane of the exposure drum) may vary.</p><p> Further, in the developing roll 1 processed by the conventional sandblasting, an abrasive material (for example, SiC powder, glass beads, etc.) sprayed at high speed from the sandblasting apparatus easily pierces the surface of the developing roll 1. Furthermore, the abrasive material that pierces the metal surface (particularly the soft metal surface such as aluminum) at high speed cannot be completely removed by ultrasonic cleaning or the like. As a result, after being incorporated into an actual printer, the abrasive material may be detached from the developing roll 1 over time, which may damage the photosensitive drum or the like.</p><p> Further, when two-dimensionally fine irregularities 7a and 7b are formed on the surface of the developing roll 1 by physical means such as sandblasting, the developing roll 1 itself is physically deformed (change in roundness, distortion, etc.). )Resulting in. In addition, there is a problem that deformation over time may occur due to processing heat due to sandblasting and internal stress (including residual stress) of the processed surface.</p><p> The present invention solves the above-mentioned conventional problems, and only prevents the occurrence of problems due to sandblasting by forming predetermined irregularities according to the particle size of the toner on the surface of the developing roll without using sandblasting. Instead, the purpose is to improve the accuracy of the developing roll and increase the amount of toner transferred to the photosensitive drum or the like.</p>

<p> And in order to achieve this purpose, the developing roll of the present invention is at least<u style="single">Silicon 0.2% or more and 0.6% or less or magnesium 0.45% or more and 0.90% or less</u>A cylindrical pipe provided of the aluminum alloy contained therein and a plurality of recesses provided on the surface of the pipe are provided, and the entire inner wall surface of the recess is covered with a plurality of recesses.<u style="single">By etching this cylindrical pipe with hydrochloric acid,</u>The alloy phase containing silicon or magnesium in the aluminum alloy constituting the pipe has a structure represented as a crystal grain boundary.</p>

<p> The developing roll of the present invention and a printing apparatus using the same can prevent toner from slipping on the surface of the developing roll, and can improve the print quality during high-speed printing. This corresponds to the particle size of the toner on substantially the entire surface of the inner wall of the recessed portion for transporting the toner.<u style="single">Concave or convex or uneven parts are formed,</u>This is because it is possible to prevent the toner from slipping when the developing roll is rotated at high speed.</p><p> In addition, since the toner is prevented from slipping by exposing the grain boundaries of this metal as an anti-slip structure, the amount of toner that can be conveyed per unit time during high-speed printing of the printer (or high-speed rotation of the developing roll). Can be increased. Furthermore, the in-plane variation of toner supply is reduced, and the uniformity of toner supply over the entire exposure roll is enhanced.</p><p> In addition, since the developing roll is not sandblasted, the dimensional accuracy of the developing roll is improved, and problems caused by sandblasting (residual abrasives on the processed surface, internal stress, etc.) do not occur, so that the developing roll is exposed to light for a long time. Stable toner supply to drums and the like is possible.</p>

(Embodiment 1) Hereinafter, the developing roll and the manufacturing method thereof according to the first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 (A) is an external view of the developing roll according to the first embodiment of the present invention, and FIG. 1 (B) is an enlarged cross-sectional view of the vicinity of the recess formed in the developing roll.

In FIGS. 1 (A) and 1 (B), 11 is a developing roll (the developing roll 11 is sometimes called a magnet roll or a developing sleeve), 12 is a recessed portion, 13 is a hollow portion, and 14a and 14b are crystal grains. Boundaries, 15a and 15b are arrows, 16 is a dotted line, 17 is a toner, and 18 is a carrier.

The crystal grain boundary 14a is a crystal grain boundary exposed on the inner wall of the recessed portion 12. The crystal grain boundaries 14b are unexposed crystal grain boundaries (or crystal grain boundaries inside the metal constituting the developing roll 11).

As shown in FIG. 1 (B), a part of the crystal grain boundaries 14b inside the metal is exposed to substantially the entire surface of the inner wall of the recess 12 in a substantially spherical or substantially circular shape. Then, the exposed crystal grain boundaries 14a prevent slipping on the toner 17 and the carrier 18. Therefore, the grain boundaries 14a exposed on the inner wall of the recess 12 are made similar to the particle size of the carrier 18.

In FIG. 1A, a plurality of recesses 12 are provided on the surface of the developing roll 11. The toner 17 and the carrier 18 are filled in a plurality of recesses 12 provided in the developing roll 11 and supplied to a photosensitive drum (not shown) as the developing roll 11 rotates. In the case of a one-component system, the toner 17 alone is conveyed in the recess 12. Further, in the case of a two-component system widely used in a color printer or the like, what is conveyed in the recess 12 is both the carrier 18 and the toner 17.

In FIG. 1 (A), a ferrite magnet or the like is inserted inside the cavity 13, but it is omitted.

FIG. 1 (B) is an enlarged cross-sectional view of the vicinity of the recess 12 shown in FIG. 1 (A). In FIG. 1 (B), the arrow 15a indicates the size of the recess 12 (for example, the dimension in the XY direction), and the arrow 15b indicates the depth of the recess 12 (for example, the depth in the Z direction).

The crystal grain boundary 14a expressed in the recessed portion 12 in FIG. 1 (B) means that a part or more of the crystal grain boundary 14b inside the developing roll 11 is expressed in a shape such as a substantially spherical shape or a substantially circular shape. It is a thing. It should be noted that it may be expressed in a concave shape as shown in FIG. 1 (B), but it may also be expressed in a convex shape. This is selected according to the intended use and toner 17 and the like.

In FIG. 1 (B), the exposed crystal grain boundaries 14a of the recessed portion 12 have a substantially spherical shape, a substantially circular shape, or a combination thereof in the XY plane. The shape of the crystal grain boundaries 14 provided for slip prevention in the Y direction (shape in the depth direction) is a bump-shaped convex shape, a concave shape, or a combination of these convex and concave shapes. In this way, by making the shape (dimensions, shape, density, etc.) of the crystal grain boundaries 14a exposed on the surface of the recessed portion 12 correspond to the shape and size of the toner 17, the anchor effect (or slip) on the toner 17 is achieved. (Prevention) is expressed.

In FIG. 1 (B), the crystal grain boundaries 14b inside the metal constituting the developing roll 11 are formed as grain boundaries of metal crystal grains such as an aluminum alloy forming the developing roll 11 to suppress variations. The grain boundaries (or the size of the grain boundaries) of the crystal particles can be confirmed by etching the cross section of these aluminum alloys or the like. By exposing a part of the crystal grain boundaries 14b to substantially the entire inner wall of the recessed portion 12 in this way, it is possible to prevent slipping on the toner 17.

It is desirable that the depth of the recess 12 is substantially constant. This is to stabilize the amount of toner 17 conveyed in the developing roll 11. The substantially constant depth means that more than half of the plurality of recesses 12 are contained within ± 30% of the depth of the arrow 15b shown in FIG. 1 (B).

The average depth of the recess 12 is preferably in the range of 10 microns or more and 300 microns or less. If the depth of the recess 12 is less than 10 microns, the amount of toner 17 and carrier 18 that are filled and transported to the recess 12 per unit time is reduced. If the depth exceeds 300 microns, it may be difficult for the toner 17 and carrier 18 filled in the recess 12 to be discharged from the recess 12 to the outside (for example, the surface of a photosensitive drum), and the unit time The amount of toner 17 or carrier 18 per hit may decrease.

It is not necessary for all the recesses 12 to have substantially the same depth. For example, multiple recesses 12a (not shown) with an average depth of 30 microns are group 1, and multiple recesses 12b (not shown) with an average depth of 60 microns are group 2, average depth. A plurality of recesses 12c (not shown) having a size of 100 microns may be used as the third group. In this way, by setting the depth to be substantially constant in each group but different average depth in the first to third groups, the low speed range, medium speed range, and high speed range of the magnet roll are set. It is possible to improve the transport stability of each toner 17 in the above.

This is to assist the transfer of the toner 17 and the carrier 18 (for example, the toner 17 and the carrier 18 on the inner wall surface of the recess 12 are not hooked or slipped) as described in FIG. 1 (B).

When the average particle size of the toner 17 is 5 microns, the average diameter of the grain boundaries 14a is 1 micron or more and 30 microns or less (preferably 20 microns or less). Further, by forming a part or more of this into a substantially spherical shape, a substantially circular shape, or a combination shape thereof, the biting property to the toner 17 is enhanced.

If the average diameter of the exposed crystal grain boundaries 14a is less than 1 micron, the anti-slip effect of the toner 17 and the carrier 18 may decrease. If the average diameter of the grain boundaries 14a exceeds 30 microns, the anti-slip effect of the toner 17 and the carrier 18 may decrease.

Assuming that the average particle size of the toner 17 is α micron, the size of the displayed grain boundary 14a (for example, the diameter in the XY plane) is preferably 20% or more and 400% or less of the α micron. This is to maximize the anti-slip effect of the toner 17 and the carrier 18 described above, and if it is less than 20% or exceeds 400%, the anti-slip effect on the toner 17 or the carrier 18 may be affected.

It is not necessary to directly relate the size of the expressed grain boundary 14a and the size of the carrier 18. This is because the toner 17 adhering to the surface of the carrier 18 (for example, 40 to 100 microns in diameter) is caught by the exposed grain boundaries 14a.

(Embodiment 2) In the second embodiment, an example of the manufacturing method of the developing roll 11 described in the first embodiment will be described.

2 (A) to 2 (C) are perspective views illustrating an example of a method for manufacturing the developing roll 11. In FIGS. 2A to 2C, 19 is a metal pipe (for example, an aluminum pipe having a diameter of about 10 mm to 30 mm and a length of about 20 cm to 50 cm, etc.), and 20 is a processing mark.

The dotted line 16 in FIG. 2 (A) shows the deformation of the metal pipe 19. As shown by the arrow 15, the metal pipe 19 may be slightly distorted or bent. Since such distortion and bending of the metal pipe 19 may affect the quality of the developing roll 11, it is removed by cutting (using a cutting tool or the like for cutting) or polishing.

FIG. 2B shows the state after the distortion and bending are reduced by polishing the outer surface of the metal pipe 19 in the circumferential direction or by cutting the outer surface of the metal pipe 19 in a spiral shape. Shown. The machining mark 20 in FIG. 2B indicates a polishing mark formed in the circumferential direction (sometimes called a cutting mark) or a spirally formed cutting mark (sometimes called a cutting mark). .. FIG. 2C shows a state in which a recess 12 for transporting the toner 17 and the carrier 18 (both not shown) is formed on the surface of the metal pipe 19 having the processing marks 20 formed on the surface.

The crystal grain boundaries 14a exposed on substantially the entire inner wall of the recess 12 in FIG. 2C are not shown.

The recessed portion 12 is formed by forming an etching resist in a predetermined pattern on the surface of the metal pipe 19 in the state of FIG. 2 (B) and etching the metal pipe 19 with an etching solution. As a method for forming the etching resist, a commercially available photosensitive resist is applied and exposed, or a resin solution or the like is sprayed (or printed) in a pattern from a commercially available printer head for an ink jet. These can be used as resist patterns (detailed description will be omitted). When the metal pipe 19 is made of aluminum, an acid or alkaline etching solution can be used. This is because aluminum is an amphoteric metal. Then, by optimizing the etching solution and the etching method, the crystal grain boundaries 14a are exposed on substantially the entire inner wall of the recessed portion 12.

Further, by repeating the steps of forming the etching resist and etching a plurality of times, as described above, for example, a plurality of recesses 12a (not shown) having an average depth of 30 microns are formed in the first group and the average depth. A plurality of recesses 12b (not shown) having an average depth of 60 microns can be created as a second group, and a plurality of recesses 12c (not shown) having an average depth of 100 microns can be created as a third group. In this way, by setting the depth to be substantially constant in each group but different average depth in the first to third groups, the low speed range, medium speed range, and high speed range of the magnet roll are set. It is possible to improve the transport stability of each toner 17 in the above.

It is desirable to form the recess 12 after forming the processing mark 20 on the surface of the metal pipe 19. By forming the machining marks 20, the roundness of the metal pipe 19 (the roundness is defined by JIS-B-0182, etc., and is sometimes called circularity in English) is improved. , The coatability of the etching resist and the uniformity of the film thickness can be improved.

The developing roll 11 has a pipe shape, and a magnetic material may be provided inside the pipe in a rotatable state to form the developing roll 11.

As the magnetic material, those proposed by the inventors in JP-A-2002-343624 and the like can be used.

As described above, in the first step of polishing or spirally cutting the outer surface of the metal pipe 19 in the circumferential direction to form a processing mark 20 on the outer surface, and after the first step, The second step of forming an etching resist on the outer surface and the crystal grain boundaries 14b of the metal member constituting the developing roll 11 on the outer surface are set as crystal grain boundaries 14a on substantially the entire inner wall of the recessed portion 12. Let it appear. After that, as a third step, a plurality of recesses 12 in which the crystal grain boundaries 14a are exposed are formed at a substantially constant depth to manufacture a developing roll 11 having high print quality during high-speed printing. ..

Further, by combining the developing roll 11 thus created, the toner 17 conveyed using the developing roll 11, and the exposure roll (not shown) to which the toner 17 is transferred, the print quality at the time of high-speed printing can be improved. An expensive printing device (for example, a color printer, etc.) can be provided.

It is desirable that the depth is approximately 10 microns or more and 300 microns or more. If the average depth of the recess 12 deviates from this range, the amount of toner 17 conveyed per unit time may decrease.

The developing roll 11 thus created has higher dimensional accuracy (for example, higher roundness or less distortion and bending) than the developing roll 1 formed by conventional sandblasting or the like. In addition, by optimizing the shape of the recess 12 provided on the surface of the developing roll 11 (the pattern in the plane direction of XY, the depth in the Z direction, etc.), the amount of toner 17 and carrier 18 transported per unit time Therefore, it is possible to increase the speed of the printer and the like, and to improve the print quality.

A magnetic material or the like is inserted into the cavity 13 of the developing roll 11 shown in FIG. 2C to form a rotatable developing roll 11, but the description of such a process step will be omitted.

This will be described in more detail. For example, when aluminum is used for the metal pipe 19, it is cost effective to use hydrochloric acid (concentration 1 wt% to 10 wt%) as the etching solution. If the concentration is less than 1 wt%, the etching will take too long. If the concentration exceeds 10 wt%, care must be taken in handling. Further, electrolytic etching (applying a voltage at the time of etching) may be performed. In that case, the hydrochloric acid concentration is preferably 1 wt% to 10 wt%. If the concentration is less than 1 wt%, etching may take too long. If the concentration exceeds 10 wt%, care must be taken in handling. When electrolytic etching is performed, it is desirable that the anode side is the work side, that is, the roll, and the cathode side is shaped to match the roll (for example, a cylindrical shape) to suppress etching variations. Further, the metal pipe used here has a crystal grain size of 20% or more and 400% or less on average of the toner.

It is desirable that the Rmax of the machining mark 20 (cut surface or polished surface) of the metal pipe 19 is as small as 10 μm or less. When Rmax is larger than 10 μm, pinholes may occur in the resist material when a resist material (photosensitive resin, UV curable resin, etc.) is applied. More preferably, Rmax should be 5 μm or less. For example, in order to reduce Rmax to 10 μm or less, buffing or sandblasting can be performed. In such a treatment, for example, by reducing Rmax to 10 μm or less (preferably 5 μm or less), bubbles of the resist material can be reduced and the adhesion strength (or peel strength) between the resist material and the substrate can be increased. JIS-B0601 can be used for Rmax, but it may be replaced with Rz (10-point average roughness).

(Embodiment 3) Next, in the third embodiment, the effect of the processing marks 20 provided on the surface of the developing roll 11 will be described with reference to FIGS. 3 to 6.

FIGS. 3 (A) and 3 (B) are cross-sectional views of a developing roll 11 having a processing mark 20 on its surface. FIG. 3A corresponds to the case where one cutting tool is used, and FIG. 3B corresponds to the case where a plurality of cutting tools are used.

The arrow 15a in FIG. 3 (A) indicates the machining mark 20 (or the width of the machining mark 20) formed by one cutting tool. By using a single cutting tool, protrusion-shaped machining marks 20 can be formed in the circumferential direction of the surface of the developing roll 11 at regular intervals A (or at a substantially even pitch A) as shown by arrow 15a. It forms continuously in a spiral shape. The arrow 15b indicates the depth of the processing mark 20.

FIG. 3B shows the machining marks 20 generated when a plurality of cutting tools are used. As shown by arrows 15c and 15d in FIG. 3B, machining marks 20 are formed at a plurality of regular intervals B and C. The dotted line 16 indicates the difference in the depth of the processing mark 20. The Rmax of the processing mark 20 is preferably 10 μm or less. Further, in FIGS. 3 (A) and 3 (B), the recessed portion 12 and the like are not shown.

4 (A) to 4 (C) are cross-sectional views and characteristic views for explaining the effect of the processing marks 20 provided on the surface of the developing roll 11. Note that the recesses 12 and the like are not shown in FIGS. 4 (A) to 4 (C).

FIG. 4A is a cross-sectional view of the developing roll 11 provided with regular processing marks 20 on the surface. Reference numeral 21 denotes a smooth portion. For example, a convex portion composed of the processing marks 20 of the developing roll 11 is set in the device, and the surface thereof is polished and smoothed. The arrow 15a in FIG. 4B shows the unevenness due to the processing mark 20.

FIG. 4B is a cross-sectional view showing a change in the surface state of the developing roll 11 provided with the regular developing roll 11 on the surface after being used for a certain period of time. The convex portion consisting of the machining mark 20 at the position indicated by the arrow 15b in FIG. 4B is gradually worn down to form the smooth portion 21. As a result, the unevenness of the processing marks 20 (for example, arrows 15a and 15b) on the developing roll 11 can be reduced in a short time.

FIG. 4C shows how the size of the unevenness on the surface of the developing roll 11 decreases with the usage time of the developing roll 11. In FIG. 4C, the X-axis shows the running time (for example, the usage time of the developing roll 11), and the Y-axis shows the unevenness of the developing roll 11. As shown in FIG. 4C, it can be seen that in the developing roll 11 of the first embodiment, the unevenness is reduced in a short time, and once the unevenness is reduced, the unevenness is unlikely to change. As described above, in the first embodiment, it can be seen that the surface of the developing roll 11 is smoothed and the print quality is stable in a short time.

Even when the initial surface roughness Rmax of the developing roll 11 is set to 10 μm or less (preferably 5 μm or less), the surface roughness rapidly decreases with time, and stable print quality can be obtained over a long period of time. Needless to say, it can be done.

Next, for comparison, FIGS. 5 (A) to (C) show changes in surface irregularities of the conventional sandblasted developing roll 1 (hereinafter referred to as the conventional developing roll 1) described in FIGS. 12 to 13 and the like. ) Will be used for explanation.

5 (A) to 5 (C) are cross-sectional views and characteristic views illustrating the effect of reducing the unevenness of the surface of the conventional developing roll 1. Reference numeral 22 in FIGS. 5 (A) and 5 (B) is a sandblasted portion. The sandblasted portion 22 shows an irregular uneven shape.

FIG. 5A is a cross-sectional view of the conventional developing roll 1 in which irregular irregularities are provided on the surface by sandblasting. The arrow 15a in FIG. 5 (A) indicates an irregular uneven step (or uneven difference) formed by sandblasting.

FIG. 5B is a cross-sectional view showing a change in the surface state of the conventional developing roll 1 provided with irregular irregularities on the surface by sandblasting after being used for a certain period of time. The convex portion shown by the arrow 15b in FIG. 5 (B) is gradually worn down to form the smooth portion 21.

FIG. 5C shows how the size of the unevenness on the surface of the conventional developing roll 1 changes with the usage time of the conventional developing roll 1. In FIG. 5C, the X-axis shows the running time (for example, the usage time of the developing roll 1), and the Y-axis shows the unevenness of the conventional developing roll 1. As shown in FIG. 5 (C), in the conventional development roll 1, even if the running time increases, the unevenness does not easily decrease. Moreover, the size of the unevenness is not constant (or stable) forever. This is because, as shown in FIGS. 5A and 5B, the sandblasting portion 22 exhibits irregular unevenness. Further, the irregular unevenness of the sandblasted portion 22 has stress remaining in the processed portion and the like, so that the degree of wear is difficult to stabilize and tends to cause variation.

(Embodiment 4) Next, in the fourth embodiment, using FIGS. 6 to 8, the recessed portion 12 provided in the developing roll 11 and the fine structure of the inner wall constituting the recessed portion 12 are described based on SEM photographs (electron micrographs). explain.

FIG. 6 is an explanatory view of the surface of the developing roll 11 using an SEM photograph of the surface of an example of the aluminum columnar developing roll 11 created by the inventors.

In the photographic portion shown in FIG. 6, the magnification is 50 times (× 50), and the dimension on the photograph (the length indicated by the arrow 15) is 500 microns. From FIG. 6, on the surface of the developing roll 11, spiral processing marks 20 are formed in the circumferential direction at regular pitches. Further, a recess 12 is formed on the surface of the developing roll 11, for example, in a quadrangular shape. Further, the crystal grain boundaries 14 for slip prevention are exposed on substantially the entire inner wall of the recessed portion 12 (or the inner wall of the recessed portion 12).

FIG. 7 is an explanatory view using an SEM photograph showing an example of the anti-slip crystal grain boundaries 14 exposed on the inner wall of the recess 12 of the developing roll 11 created by the inventors. In FIG. 7, the magnification is 500 times (× 500), and the photographic dimension (length indicated by arrow 15) is 50 microns. From FIG. 7, innumerable grain boundaries 14 due to substantially bump-shaped convex portions or concave portions of various sizes, or a combination of these irregularities are exposed over substantially the entire inner wall of the recessed portion 12. I understand.

It is desirable that the average diameter at the exposed portion of the exposed crystal grain boundary 14 is 1 micron or more and 30 microns (preferably 20 microns) or less, and has a plurality of sizes. With such a shape or distribution, even when the developing roll 11 is rotated at high speed, the toner 17 and the carrier 18 (both not shown) that have entered the recess 12 are hard to slip (or slip). Hateful). As a result, even when the printer prints at high speed, the amount of toner 17 conveyed in the recess 12 per unit time of the carrier 18 does not decrease, so that the print quality is stabilized.

FIG. 8 is an explanatory view using an SEM photograph showing another example of the grain boundary 14 formed on the inner wall of the recess 12 of the developing roll 11 created by the inventors. In FIG. 8, the magnification is 500 times (× 500), and the photographic dimension (length indicated by arrow 15) is 50 microns. From FIG. 8, it can be seen that the crystal grain boundaries 14 due to the substantially bump-shaped convex portions or concave portions of various sizes, or the combination of these irregularities are exposed over substantially the entire inner wall of the recessed portion 12. ..

The exposed state (or exposed density) of the crystal grain boundaries 14 may be densely generated in the recesses 12 as shown in FIG. 7 depending on the intended use of the developing roll 11, and is also shown in FIG. It may be generated sparsely in the recessed portion 12 as described above. The coarse density of the crystal grain boundaries 14 exposed on the inner wall of the recessed portion 12 may be changed according to the intended use and the like. However, it is desirable to provide 5 or more, preferably 10 or more substantially spherical or substantially circular shapes in an area of at least 100 micron square. If the number is less than 5, the anti-slip effect may be low.

It is desirable that the size of the expressed grain boundaries 14 has an average diameter of 1 micron or more and 30 microns (preferably 20 microns) or less regardless of the density. Then, as shown in FIG. 7, a plurality of individual crystal grain boundaries 14 are formed so as to overlap each other in an infinite number, thereby further preventing slippage. By forming a shape or distribution in which a plurality of toners having a plurality of sizes, large or small, and a plurality of sizes are combined in this way, the toner 17 and the carrier in the recess 12 are formed even when the developing roll 11 is rotated at high speed. 18 is hard to slip in the recess 12. As a result, even when the printer prints at high speed, the amount of toner 17 conveyed in the recess 12 per unit time of the carrier 18 does not decrease, so that the print quality is stabilized.

As described above, the individual average diameters of the expressed grain boundaries 14 are 1 micron or more and 30 microns (preferably 20 microns) or less, and the average grain size of the grain boundaries 14 is the average particle size of the toner. By setting it to 20% or more and 400% or less of the above, slip prevention is further ensured.

In particular, in recent years, as the toner 17 conveyed using the recessed portion 12, fine toner 17 is often used in order to improve the print quality. Such fine toner 17 itself has a small tap density, which makes it fluffy and difficult to handle (and easily slips on the developing roll 11). However, by displaying the crystal grain boundaries 14 corresponding to the particle size of the toner 17 as shown in FIGS. 7 to 8, it is possible to prevent the toner 17 from slipping. The average particle size of the toner 17 is the primary particles of the toner 17. This is because the primary particles of the toner 17 are caught on the surface of the exposed crystal grain boundaries 14 and the like, so that the secondary particles can also be conveyed.

Next, the surface of the conventional developing roll 1 prepared by the conventional sandblasting will be described with reference to FIGS. 9 to 10.

FIG. 9 shows an SEM photograph of the surface of a sandblasted aluminum columnar developing roll. In FIG. 9, the magnification is 50 times (× 50) and the photographic dimension (length indicated by arrow 15) is 500 microns.

As shown in FIG. 9, it can be seen that the sandblasted surface has innumerable depressions of about 100 microns. Toner 17 (not shown, eg, 4 microns in diameter), on the other hand, is orders of magnitude smaller than the sandblasted recesses. Therefore, as shown in FIG. 13, it is difficult to obtain the slip prevention effect of the toner 17 on the uneven surface formed by sandblasting.

Next, with reference to FIG. 10, the details of the innumerable recesses formed by sandblasting will be described.

FIG. 10 is an explanatory view of the surface of the conventional roll using an SEM photograph of the surface of the conventional developing roll 1 created by the inventors using sandblasting.

In the photographic portion shown in FIG. 10, the magnification is 500 times (× 500), and the dimension on the photograph (the length indicated by the arrow 15) is 50 microns.

In FIG. 10, 23 is a dented part and 24 is a scratched part. As shown in FIG. 10, on the uneven surface formed by sandblasting, a dent portion 23 generated by the collision of the sandblast material and a scratched portion 24 generated by the collision of the sandblast material are generated.

The toner 17 adhering to such scratches 24 cannot be collected in a toner box or the like, which may cause stains.

Further, from the elemental analysis of the inventors (not shown), it was confirmed that the sandblast material (for example, glass, alumina, silicon carbide, etc.) bites into the inside of the scratched portion 24. In addition, it is difficult to completely remove the sandblast residue remaining on the scratched portion 24 by ultrasonic cleaning, and it may be released to the outside together with the toner 17 and the carrier 18 over time, which damages the photosensitive drum and the like. there is a possibility.

As shown in FIGS. 9 to 10, in the case of the conventional sandblasting process, the size of the unevenness formed by the sandblasting (in the XY direction) was about 100 to 200 μm, and the variation was also large. In addition, it is difficult to obtain the slip prevention effect of the toner 17 having a particle size of about 5 μm. The height of the unevenness formed by sandblasting (Z direction) was also 5 to 30 microns according to the measurement by the inventors, and the variation was large.

Next, the result of comparing the characteristics of these developing rolls will be described.

The inventors used the developing roll 11 (product of the present invention) shown in FIGS. 1 to 4 and 6 to 8 and the developing roll 1 (conventional product) shown in FIGS. 5 and 9 to 10. Evaluation was performed.

The development roll 11, which is the product of the present invention, has higher print quality and less quality variation during high-speed printing than the development roll 1, which is the conventional product. On the other hand, in the case of the development roll 1 which is a conventional product, the print quality varies during high-speed printing. It is considered that this is because the product of the present invention contributed to the slip reducing effect of the grain boundaries 14 on the toner 17.

(Embodiment 5) Next, in the fifth embodiment, the metal material used for the developing roll 11 will be described.

It is desirable to use AL (aluminum) for the developing roll 11 rather than SUS (stainless steel). When SUS is used, it is difficult to form the recess 12 by etching. Further, it may be difficult to control the grain boundaries 14 to be exposed in order to prevent the recessed portion 12 from slipping to the inner wall.

On the other hand, by using aluminum for the developing roll 11, it becomes easy to form the recessed portion 12 by etching. Also, compared to SUS, aluminum has a lower specific gravity, which enables high-speed rotation of the magnet roll with less energy.

The developing roll 11 (or the metal pipe 19 that is a constituent member of the developing roll 11) is preferably an aluminum alloy containing at least 0.20% or more and 0.60% or less of silicon, or 0.45% or more and 0.90% or less of magnesium. By using an aluminum alloy containing at least 0.20% or more and 0.60% or less of silicon, or 0.45% or more and 0.90% or less of magnesium (further), the workability of the metal pipe 19 by cutting or polishing is improved, and the metal pipe 19 is positively etched. The size of the crystal grain boundary 14 expressed in the recessed portion 12 can be controlled in the range of 5 to 30 microns (preferably 20 microns). In addition, metal components other than aluminum contained in aluminum alloys such as silicon, magnesium, iron, chromium, and titanium are added to the interface and boundary of the grain boundaries 14.<u style="single">positive</u>By precipitating in, the fine structure caused by these grain boundaries 14 can be prevented from being worn down. As a result, the anti-slip effect of the toner 17 is unlikely to decrease over a long period of time.

As described above, the developing roll and the manufacturing method thereof according to the present invention can increase the amount of toner and carriers transported per unit time during high-speed printing due to the recessed portion and the anti-slip structure formed on the surface thereof. More stable printing characteristics of blinters and copying devices can be obtained.

<figref num="1">(A) is an external view of the developing roll according to the first embodiment of the present invention, and (B) is an enlarged cross-sectional view of the vicinity of the recess formed in the developing roll.</figref><figref num="2">(A) to (C) are perspective views illustrating an example of a method for manufacturing a developing roll.</figref><figref num="3">(A) and (B) are cross-sectional views of a developing roll having processing marks on its surface.</figref><figref num="4">(A) to (C) are cross-sectional views and characteristic views for explaining the effect of the processing marks provided on the surface of the developing roll.</figref><figref num="5">(A) to (C) are cross-sectional views and characteristic views for explaining the effect of reducing the unevenness on the surface of the conventional developing roll.</figref><figref num="6">Explanatory drawing of the surface of the developing roll using the SEM photograph of the surface of an example of the cylindrical developing roll created by the inventors.</figref><figref num="7">Explanatory drawing using SEM photograph showing an example of the grain boundary shape formed on the inner wall of the recessed portion of the developing roll created by the inventors.</figref><figref num="8">Explanatory drawing using SEM photograph showing another example of the grain boundary shape formed on the inner wall of the recessed portion of the developing roll created by the inventors.</figref><figref num="9">Explanatory drawing of the surface of the conventional roll using the SEM photograph of the surface of the conventional developing roll created by the inventors using sandblasting.</figref><figref num="10">Explanatory drawing of the surface of the conventional roll using the SEM photograph of the surface of the conventional developing roll created by the inventors using sandblasting.</figref><figref num="11">(A) is a perspective view showing an example of the developing roll proposed in Patent Document 1, and (B) is a perspective view showing an example of the developing roll proposed in Patent Document 2.</figref><figref num="12">Cross-sectional view showing a part of the developing roll proposed in Patent Document 3.</figref><figref num="13">Cross-sectional view for explaining how toner particles slip on the secondary fine irregularities 7 provided in the recessed portion.</figref>

Code description

11 Develop roll 12 dent 13 Cavity 14a, 14b Grain boundaries 15 arrow 16 dotted line 17 Toner 18 carrier 19 metal pipe 20 Processing marks 21 Smooth part 22 Sandblasting section 23 dent 24 wound