JP2010128269A - Developing roll, method for manufacturing the same, and printing device - Google Patents

Abstract

When high-speed printing is performed using a developing roll used in a copying machine, a printer, or the like, toner slips on the surface of the developing roll, and print quality may deteriorate.
A plurality of depressions 12 having a substantially constant depth for conveying toner 17 are provided on the surface of a metal developing roll 11, and a part or more is provided on substantially the entire inner wall of the depressions 12. Prevents the toner 17 from slipping on the surface of the recess 12 during high-speed printing, and increases the transport amount per unit time. Reduce amount variation.
[Selection] Figure 1

Description

  The present invention relates to a developing roll used in a printing apparatus using toner, such as a copying machine, a laser printer, and a facsimile machine, a manufacturing method thereof, and a printing apparatus.

  Printing devices using toner, such as laser printers, are required to have higher speed or higher printing quality. In order to meet these market needs, the developing roll that supplies each color toner to the photosensitive drum that constitutes the laser printer has a smaller diameter corresponding to the downsizing of the printer and an increase in the amount of toner that can be conveyed per unit time. Alternatively, toner supply uniformity and the like are required.

  Therefore, the developing roll is required to supply toner to the photosensitive drum with a smaller diameter and higher speed rotation. Therefore, in order to make the printer compatible with high-speed printing, an increase in the transport amount per unit time and stabilization thereof are required on the developing roll side. Here, the developing roll is a metal cylindrical shape, and a developing roll is configured by inserting a rod-shaped magnet or the like into the inside thereof.

  Next, a conventional developing roll will be described with reference to FIGS.

  FIG. 11A is a perspective view showing an example of the developing roll proposed in Patent Document 1, and FIG. 11B 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 “roll” of the developing roll 1a is reduced by cutting the surface so that the cutting groove 2 is provided in the longitudinal direction on the surface.

  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, unevenness occurs in the circumferential direction of the developing roll 1b, thereby causing uneven charging due to the “around” of the brush when the magnetic brush charging method is used as the charging device. To prevent that.

  In addition, although the cylindrical magnet member etc. are inserted in the cavity part 3 in FIG. 11 (A) (B), these are not shown in figure.

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

  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 recess 6 in the developing roll 1 is a portion that is not protected by the resist pattern, and corresponds to a portion in which aluminum is removed in a concave shape with caustic soda. The top 5 corresponds to a portion protected by the resist pattern and not etched.

  In addition, after forming the top part 5 and the hollow part 6 on the surface of the developing roll 1 in FIG. 12, a sand blasting process is further performed thereon, and after this sand blasting process, the top part is polished with a buff. is there. By performing sandblasting on the developing roll 1 in which the top 5 and the depression 6 are formed in this way, uniform unevenness can be formed on the entire surface of the developing roll 1. Further, the secondary fine unevenness 7a of the top 5 is more than the secondary fine unevenness 7b provided in the recess 6 by buffing or the like (or by selectively polishing the top 5). By reducing the size, the influence on the fusing and blotching of low-melting toner and the conveyance force before and after the durability is reduced.

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

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

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

However, the secondary fine irregularities 7b are also one or more orders of magnitude larger than the particle size of the toner 8. As described above, the size of the secondary fine irregularities 7b in the plane is 100 microns or more, which is one digit or more 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 irregularities 7b formed by sandblasting. In other words, even the secondary fine irregularities 7 b are very large with respect to the toner 8, so that it is difficult to obtain an anchor effect (or a catching effect), and as indicated by an arrow 9, the surface of the recess 6 (or The toner 8 tends to slip on the inner wall surface.
JP-A-5-158349 JP 2006-317684 A JP-A-11-133728

  However, the conventional developing roll 1 still has problems in the increase in the amount of toner that can be conveyed per unit time and the uniformity in high-speed printing required from the toner supply market.

  For example, in the case shown in FIGS. 11A and 11B, the amount of toner that can be held on the surfaces of the developing rolls 1a and 1b is caused by the processing accuracy, and may be easily affected by variations in processing.

  In the case shown in FIG. 12, the toner is held in the depression 6, but when the toner particle size becomes a few microns as the print quality improves, the toner slips in the depression 6. There was a case. On the other hand, the unevenness formed by sandblasting has a size in the XY direction (for example, a plane or a circumferential direction) of 100 microns or more and a depth in the Z direction (for example, a thickness direction) of several tens of microns. This is because processing by sand blasting is performed by collision of abrasives ejected at high speed from a sand blasting device (for example, collision energy). When the sand blasting material is made fine, the kinetic energy of the abrasives is extremely reduced, Its workability is reduced.

  For this reason, the unevenness formed by sandblasting is one digit or more 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.

  In addition, the sandblasting process causes fine scratches on the surface of the developing roll, which causes toner adhesion. The toner adhering to the scratches cannot be collected in a toner box or the like, causing stains.

  As described above, when the developing roll 1 made using conventional sandblasting rotates at high speed, toner particles and the like slip on the surface, and the toner conveyance amount increases per unit time and the toner conveyance amount is stabilized. Alternatively, the toner supply amount in the surface of the developing roll 1 (or in the surface of the exposure drum) may vary.

  Further, in the developing roll 1 processed by conventional sandblasting, an abrasive (for example, SiC powder or glass beads) sprayed at a high speed from a sandblasting device is likely to pierce the surface of the developing roll 1. Furthermore, the abrasive that has pierced the metal surface (particularly a soft metal surface such as aluminum) at a high speed cannot be removed by ultrasonic cleaning or the like. As a result, after being incorporated into an actual printer, the abrasive may be detached from the developing roll 1 over time, and the photosensitive drum or the like may be damaged.

  When the 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 with time may occur due to processing heat due to sandblasting, internal stress (including residual stress) on the processed surface, or the like.

  The present invention solves the above-described conventional problems, and by forming predetermined irregularities according to the particle size of the toner on the surface of the developing roll without using sand blasting, only prevention of problems due to sand blasting is prevented. In other words, the purpose is to increase the accuracy of the developing roll and increase the amount of toner transported to the photosensitive drum or the like.

  In order to achieve this object, the present invention provides a metal developing roll provided with a plurality of depressions having a substantially constant depth for conveying toner, on the surface of the inner wall of the depressions. A developing roll in which a part or more of a crystal grain boundary of a substantially spherical shape or a substantially circular shape corresponding to the average particle diameter of the toner is exposed on substantially the entire surface.

  According to the developing roll, the manufacturing method thereof, and the printing apparatus of the present invention, toner slip on the surface of the developing roll can be prevented, and the print quality at the time of high-speed printing can be improved. This is because a crystal grain boundary of a partially spherical or circular metal corresponding to the particle diameter of the toner is exposed as a kind of anti-slip structure on substantially the entire inner wall of the recess for conveying the toner. This is because it is possible to prevent the toner from slipping when the developing roll rotates at high speed.

  In addition, the amount of toner that can be transported per unit time during high-speed printing of the printer (or during the high-speed rotation of the developing roll) in order to prevent toner slip by exposing the metal crystal grain boundaries as an anti-slip structure. Can increase the increase. Further, the in-plane variation of the toner supply is reduced and the uniformity of the toner supply over the entire exposure roll is increased.

  In addition, since the developing roll is not subjected to sandblasting, the dimensional accuracy of the developing roll is increased, and problems caused by sandblasting (such as residual abrasives and internal stress on the processed surface) do not occur. Stable toner supply to a drum or the like becomes possible.

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

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

  1A and 1B, reference numeral 11 denotes a developing roll (the developing roll 11 is sometimes called a magnet roll or a developing sleeve), 12 is a recess, 13 is a cavity, and 14a and 14b are crystal grains. Fields 15a and 15b are arrows, 16 is a dotted line, 17 is toner, and 18 is a carrier.

  The crystal grain boundary 14 a is a crystal grain boundary exposed on the inner wall of the recess 12. The crystal grain boundary 14b is a crystal grain boundary that is not exposed (or a crystal grain boundary inside the metal constituting the developing roll 11).

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

  In FIG. 1A, a plurality of depressions 12 are provided on the surface of the developing roll 11. The toner 17 and the carrier 18 are filled in a plurality of depressions 12 provided on the developing roll 11 and are 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 by the depression 12. In the case of a two-component system widely used in a color printer or the like, what is conveyed by the depression 12 is both the carrier 18 and the toner 17.

  In FIG. 1A, a ferrite magnet or the like is inserted into the cavity 13 but is omitted.

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

  In FIG. 1 (B), the crystal grain boundary 14a exposed in the recess 12 is a part of the crystal grain boundary 14b inside the developing roll 11 exposed in a shape such as a substantially spherical shape or a substantially circular shape. It is a thing. Although it may be expressed in a concave shape as shown in FIG. 1B, it may be expressed in a convex shape. This is selected according to the application to be used, the toner 17 and the like.

  In FIG. 1B, the crystal grain boundary 14a exposed from the recess 12 is substantially spherical or substantially circular or a combination thereof in the XY plane. Further, the shape in the Y direction (the shape in the depth direction) of the crystal grain boundary 14 provided for slip prevention is a bump-like convex shape, a concave shape, or a combination shape of these convex shape and concave shape. As described above, the shape (size, shape, density, etc.) of the crystal grain boundary 14 a exposed on the surface of the recess 12 is made to correspond to the shape and size of the toner 17, whereby the anchor effect (or slip) on the toner 17 is achieved. Prevention).

  In FIG. 1B, the crystal grain boundary 14 b inside the metal constituting the developing roll 11 is suppressed by being a grain boundary of metal crystal grains such as an aluminum alloy forming the developing roll 11. Note that the grain boundaries of crystal grains (or the size of the grain boundaries) can be confirmed by etching the cross section of the aluminum alloy or the like. Thus, by causing a part of the crystal grain boundary 14 b to be exposed on the substantially entire surface of the inner wall of the recess portion 12, it is possible to prevent the toner 17 from slipping.

  In addition, it is desirable that the depth of the recessed portion 12 is substantially constant. This is to stabilize the transport amount of the toner 17 on the developing roll 11. It should be noted that the substantially constant depth is sufficient if more than half of the plurality of depressions 12 is within ± 30% of the depth of the arrow 15b shown in FIG.

  The average depth of the recess 12 is preferably in the range of 10 to 300 microns. When the depth of the recess 12 is less than 10 microns, the transport amount per unit time of the toner 17 and the carrier 18 that are filled in the recess 12 and transported decreases. When the depth exceeds 300 microns, the toner 17 and the carrier 18 filled in the dent 12 may be difficult to be discharged from the dent 12 to the outside (for example, the surface of the photosensitive drum). There are cases where the amount of toner 17 or the carrier 18 that is hit decreases.

  Note that it is not necessary for all the recessed portions 12 to have substantially the same depth. For example, a plurality of depressions 12a (not shown) having an average depth of 30 microns are provided in the first group, and a plurality of depressions 12b (not shown) having an average depth of 60 microns are provided in the second group. A plurality of depressions 12c (not shown) having a length of 100 microns may be used as the third group. Thus, in each group, although it is set as a substantially constant depth, it is set as a different average depth in the 1st group-the 3rd group, and the low-speed area, the medium-speed area, and the high-speed area of a magnet roll. Therefore, the conveyance stability of each toner 17 can be improved.

  Thus, as described in FIG. 1B, the toner 17 and the carrier 18 are facilitated to be transported (for example, the toner 17 and the carrier 18 on the inner wall surface of the recess 12 are caught or not slipped).

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

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

  If the average particle diameter of the toner 17 is α microns, the size of the crystal grain boundaries 14a to be exposed (for example, the diameter in the XY plane) is preferably 20% or more and 400% or less of α microns. This is for maximizing 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 for the toner 17 and the carrier 18 may be affected.

  It is not necessary to directly relate the size of the crystal grain boundary 14a to be exposed to the size of the carrier 18. This is because an infinite number of toners 17 adhering to the surface of the carrier 18 (for example, 40 to 100 microns in diameter) are caught by the exposed crystal grain boundaries 14a.

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

  2A to 2C are perspective views illustrating an example of a method for manufacturing the developing roll 11. 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), and 20 is a processing mark.

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

  FIG. 2B shows the state after reducing the distortion and bending 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. Show. Note that the machining mark 20 in FIG. 2B indicates a grinding mark formed in the circumferential direction (sometimes referred to as a cutting mark) or a spiral cut mark (also referred to as a cutting mark). . FIG. 2C shows a state in which the depression 12 for transporting the toner 17 and the carrier 18 (both not shown) is formed on the surface of the metal pipe 19 on which the processing marks 20 are formed.

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

  The depression 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. 2B and etching the metal pipe 19 with an etching solution. As a method for forming an 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 explanation is omitted). When the metal pipe 19 is made of aluminum, an acid or alkali 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 recess 12.

  Further, by repeating the steps of forming the etching resist to 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. Can be formed with a plurality of depressions 12b (not shown) of 60 microns as a second group and a plurality of depressions 12c (not shown) with an average depth of 100 microns as a third group. Thus, in each group, although it is set as a substantially constant depth, it is set as a different average depth in the 1st group-the 3rd group, and the low-speed area, the medium-speed area, and the high-speed area of a magnet roll. Therefore, the conveyance stability of each toner 17 can be improved.

  In addition, after forming the processing trace 20 on the surface of the metal pipe 19, it is desirable to form the hollow part 12. This is because the roundness of the metal pipe 19 (note that the roundness is defined in JIS-B-0182 etc., and is sometimes called circularity in English) by forming the processing mark 20. Further, the coating property of the etching resist and the uniformity of the film thickness can be improved.

  The developing roll 11 is in the form of a pipe, and a magnetic body is provided in a rotatable state inside the pipe to form the developing roll 11.

  In addition, what was proposed by inventors by Unexamined-Japanese-Patent No. 2002-343624 etc. can be used as a magnetic body.

  As described above, the first surface of the outer surface of the metal pipe 19 is polished or spirally cut in the circumferential direction to form the processing mark 20 on the outer surface, and after the first step, A second step of forming an etching resist on the outer surface, a crystal grain boundary 14b of the metal member constituting the developing roll 11 on the outer surface, and a crystal grain boundary 14a on substantially the entire inner wall of the recess 12 Make it appear. Thereafter, as a third step, a plurality of the recessed portions 12 where the crystal grain boundaries 14a are exposed are formed at a substantially constant depth, thereby producing the developing roll 11 having high printing quality at the time of high-speed printing. .

  Further, by combining the developing roll 11 created in this way, 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. A high printing device (for example, a color printer) can be provided.

  The substantially constant depth is preferably in the range of 10 to 300 microns. If the average depth of the recess 12 is out of this range, the transport amount of the toner 17 per unit time may decrease.

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

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

  This will be described in more detail. For example, when aluminum is used for the metal pipe 19, it is desirable in terms of cost to use hydrochloric acid (concentration 1 wt% to 10 wt%) as an etchant. When the concentration is less than 1 wt%, etching takes too much time. Further, when the concentration exceeds 10 wt%, care must be taken in handling. Further, electrolytic etching (applying a voltage during etching) may be performed. In that case, the hydrochloric acid concentration is desirably 1 wt% to 10 wt%. When the concentration is less than 1 wt%, etching may take too much time. If the concentration exceeds 10 wt%, care must be taken in handling. In addition, when performing electrolytic etching, it is desirable that the anode side be a work side, that is, a roll, and that the variation in etching be suppressed by making the cathode side a shape (for example, a cylindrical shape) that matches the shape of the roll. The metal pipe used here has a crystal grain size of 20% or more and 400% or less of the average particle size of the toner.

  It should be noted that Rmax of the processing trace 20 (cutting surface or polishing surface) of the metal pipe 19 is desirably as small as 10 μm or less. When Rmax is larger than 10 μm, when a resist material (photosensitive resin, UV curable resin, or the like) is applied, pin holes may occur in the resist material. More desirably, Rmax is 5 μm or less. For example, in order to reduce Rmax to 10 μm or less, buffing or sand blasting can be performed. In such a process, for example, by reducing Rmax to 10 μm or less (preferably 5 μm or less), the foam of the resist material can be reduced and the adhesion strength (or peel strength) between the resist material and the base can be increased. In addition, although Rmax can use JIS-B0601, you may replace with Rz (10-point average roughness).

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

  3A and 3B are cross-sectional views of the developing roll 11 provided with a processing mark 20 on the surface. 3A corresponds to the case where a single cutting tool is used, and FIG. 3B corresponds to the case where a plurality of cutting tools are used.

  An arrow 15a in FIG. 3A indicates a processing mark 20 (or a width of the processing mark 20) formed by one cutting tool. By using a single cutting tool, projection-like processing marks 20 are formed in the circumferential direction of the surface of the developing roll 11 at regular intervals A (or at substantially equal pitches A) as indicated by arrows 15a. It is formed continuously in a spiral shape. An arrow 15b indicates the depth of the processing mark 20.

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

  4A to 4C are a cross-sectional view and a characteristic diagram for explaining the effect of the processing mark 20 provided on the surface of the developing roll 11. In addition, in FIG. 4 (A)-(C), the hollow part 12 grade | etc., Is not illustrated.

  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 formed of a processing mark 20 of the developing roll 11 is set in an apparatus, and the surface thereof is polished and smoothed. In addition, the arrow 15a in FIG. 4 (B) shows the unevenness | corrugation by the process trace 20. FIG.

  FIG. 4B is a cross-sectional view showing changes in the surface state after the developing roll 11 provided with the regular developing roll 11 on the surface is used for a certain period of time. The convex part which consists of the process trace 20 in the position shown by the arrow 15b of FIG.4 (B) gradually wears down, and comprises the smooth part 21. FIG. As a result, the unevenness (for example, arrows 15a and 15b) of the processing mark 20 on the developing roll 11 can be reduced in a short time.

  FIG. 4C shows a state in which the size of the irregularities on the surface of the developing roll 11 decreases with the usage time of the developing roll 11. In FIG. 4C, the X axis indicates the running time (for example, the usage time of the developing roll 11), and the Y axis indicates the unevenness of the developing roll 11. As shown in FIG. 4C, it can be seen that in the developing roll 11 of Embodiment 1, the unevenness is reduced in a short time, and once the unevenness is reduced, the unevenness is hardly changed. Thus, in Embodiment 1, it turns out that the surface of the developing roll 11 is smoothed in a short time, and the printing quality is stabilized.

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

  Next, for comparison, FIGS. 5A to 5C show changes over time in the surface roughness of the conventional sandblasted developing roll 1 (hereinafter referred to as the conventional developing roll 1) described with reference to FIGS. ).

  5A to 5C are a cross-sectional view and a characteristic diagram for explaining the effect of reducing the unevenness of the surface of the conventional developing roll 1. In FIGS. 5A and 5B, reference numeral 22 denotes a sandblasting portion. And the sandblast processing part 22 shows irregular uneven | corrugated shape.

  FIG. 5A is a cross-sectional view of a conventional developing roll 1 in which irregular irregularities are provided on the surface by sandblasting. An arrow 15a in FIG. 5A 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 after the conventional developing roll 1 having irregular concavo-convex surface provided by sandblasting for a certain period of time. The convex portion shown by the arrow 15 b in FIG. 5B is gradually worn away to constitute the smooth portion 21.

  FIG. 5C shows a state in which the size of the irregularities 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 indicates the running time (for example, the usage time of the developing roll 1), and the Y axis indicates the unevenness of the conventional developing roll 1. As shown in FIG. 5C, in the conventional developing roll 1, the unevenness is not easily reduced even when the Running time is increased. Also, the size of the unevenness will not be constant (or stable) indefinitely. This is because the sandblasting portion 22 shows irregular irregularities as shown in FIGS. Furthermore, since the irregular irregularities of the sandblasted portion 22 remain stressed in the processed portion or the like, the degree of wear is difficult to stabilize and tends to cause variation.

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

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

  In the photograph part 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. As shown in FIG. 6, spiral processing marks 20 are formed at regular pitches on the surface of the developing roll 11 in the circumferential direction. Further, a depression 12 is formed on the surface of the developing roll 11 in, for example, a square shape. A crystal grain boundary 14 for preventing slipping is exposed on substantially the entire inner wall of the recess 12 (or the inner wall of the recess 12).

  FIG. 7 is an explanatory diagram using an SEM photograph showing an example of a crystal grain boundary 14 for preventing slipping, which is 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 dimension on the photograph (the length indicated by the arrow 15) is 50 microns. As shown in FIG. 7, the infinite number of crystal grain boundaries 14 appearing on the substantially entire inner wall of the recess 12, each having an approximately ridge-like protrusion, a recess, or a combination of these irregularities of various sizes. I understand.

  It is desirable that the average diameter at the exposed portion of the exposed crystal grain boundary 14 be 1 micron or more and 30 microns (preferably 20 microns) or less, and have a plurality of sizes. By adopting such a shape or distribution, even when the developing roll 11 is rotated at a high speed, the toner 17 and the carrier 18 (both not shown) entering the recess 12 are not easily slipped (or slipped). Hateful). As a result, even when the printer performs high-speed printing, the toner 17 that has entered the recess 12 does not decrease the transport amount of the carrier 18 per unit time, so that the printing quality is stabilized.

  FIG. 8 is an explanatory view using an SEM photograph showing another example of the crystal 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 dimension on the photograph (the length indicated by the arrow 15) is 50 microns. From FIG. 8, it can be seen that a crystal grain boundary 14 is exposed over substantially the entire inner wall of the recess 12 by a large or small convex-shaped convex portion, a concave portion, or a combination of these concave and convex portions. .

  Note that the exposed state (or exposed density) of the crystal grain boundaries 14 may be densely generated in the recessed portion 12 as shown in FIG. In this way, the dents 12 may be generated sparsely. What is necessary is just to change the coarse density of the crystal grain boundary 14 exposed on the inner wall of the hollow part 12 according to a use application. 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 microns square. If it is less than 5, the anti-slip effect may be low.

  It is to be noted that the size of the exposed grain boundary 14 is desirably in the range of an average diameter of 1 to 30 microns (preferably 20 microns) regardless of its density. Further, as shown in FIG. 7, the individual crystal grain boundaries 14 are formed innumerably so as to be overlapped by a plurality of sizes, thereby further preventing slip. Thus, the toner 17 and the carrier contained in the depression 12 can be obtained even when the developing roll 11 is rotated at a high speed by forming a shape or a distribution in which a plurality of sizes, sizes, and sizes are combined. 18 is difficult to slip in the recess 12. As a result, even when the printer performs high-speed printing, the toner 17 that has entered the recess 12 does not decrease the transport amount of the carrier 18 per unit time, so that the printing quality is stabilized.

  As described above, the individual average diameters of the exposed crystal grain boundaries 14 are 1 micron or more and 30 microns (desirably 20 microns) or less, and the average grain size of the crystal grain boundaries 14 is the average grain size of the toner. Slip prevention is further ensured by setting the ratio to 20% to 400%.

  Particularly in recent years, fine toner 17 is often used for the toner 17 conveyed using the depression 12 in order to improve the print quality. Such a fine toner 17 itself has a small tap density and is difficult to handle in a fluffy manner (and easily slips on the developing roll 11). However, it is possible to prevent the toner 17 from slipping by exposing the crystal grain boundaries 14 corresponding to the particle diameter of the toner 17 as shown in FIGS. The average particle diameter of the toner 17 is the primary particle of the toner 17. This is because the primary particles of the toner 17 are caught on the surface of the exposed crystal grain boundary 14 and the secondary particles can also be conveyed.

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

  FIG. 9 shows an SEM photograph of the surface of an aluminum cylindrical developing roll that has been sandblasted. In FIG. 9, the magnification is 50 times (× 50), and the dimension on the photograph (the length indicated by the 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. On the other hand, the toner 17 (not shown, for example, 4 microns in diameter) is orders of magnitude smaller than a depression formed by sandblasting. For this reason, 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, the details of innumerable recesses formed by sandblasting will be described with reference to FIG.

  FIG. 10 is an explanatory diagram 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 photograph part 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 dent part and 24 is a flaw part. As shown in FIG. 10, a dent portion 23 generated by the collision of the sandblasting material and a scratched portion 24 generated by the collision of the sandblasting material are generated on the uneven surface formed by sandblasting.

  The toner 17 adhering to the scratches 24 cannot be collected in a toner box or the like and may cause dirt.

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

  As shown in FIGS. 9 to 10, in the case of conventional sandblasting, the size of the irregularities formed by sandblasting (XY direction) was about 100 to 200 μm, and the variation was also large. Further, the slip prevention effect of the toner 17 having a particle diameter of about 5 μm is hardly obtained. Further, the height (Z direction) of the unevenness formed by sandblasting was 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 use the developing roll 11 (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 developing roll 11 which is the product of the present invention has higher printing quality at high-speed printing and less quality variation than the developing roll 1 which is the conventional product. On the other hand, in the case of the developing roll 1 which is a conventional product, the printing quality at the time of high-speed printing varies. This is probably because the slip reduction effect of the crystal grain boundary 14 on the toner 17 contributed to the product of the present invention.

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

  The developing roll 11 is preferably made of AL (aluminum) rather than SUS (stainless steel). When SUS is used, it is difficult to form the recess 12 by etching. In addition, it may be difficult to control the crystal grain boundary 14 to be exposed to prevent slippage to the inner wall of the recess 12.

  On the other hand, the use of aluminum for the developing roll 11 facilitates formation of the recess 12 by etching. In addition, compared with SUS, aluminum has a lower specific gravity, so that the magnet roll can be rotated at high speed with less energy.

  The developing roll 11 (or the metal pipe 19 that is a constituent member of the developing roll 11) includes at least silicon of 0.20% to 0.60%, or magnesium of 0.45% to 0.90%. It is desirable to use an aluminum alloy. By making an aluminum alloy containing at least 0.20% or more and 0.60% or less of silicon or (further) 0.45% or more and 0.90% or less of magnesium, workability by cutting or polishing of the metal pipe 19 is achieved. In addition, the size of the crystal grain boundary 14 that is positively exposed to the depression 12 can be controlled within a range of 5 to 30 microns (desirably 20 microns) by etching. In addition, by precipitating metal components other than aluminum contained in an aluminum alloy such as silicon, magnesium, iron, chromium, titanium, etc. at the interface or boundary portion of the crystal grain boundary 14, these crystal grain boundaries The fine structure resulting from 14 can be hard to be worn away. As a result, the anti-slip effect of the toner 17 is unlikely to deteriorate 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 carrier transported per unit time during high-speed printing by a depression or anti-slip structure formed on the surface thereof. More stable printing characteristics of printers and copiers can be obtained.

(A) is an external view of the developing roll in Embodiment 1 of this invention, (B) is an expanded sectional view of the hollow part vicinity formed in the developing roll. (A)-(C) are perspective views explaining an example of the manufacturing method of a developing roll. (A) and (B) are cross-sectional views of a developing roll having a processing mark on the surface. (A)-(C) are sectional drawing and characteristic figure explaining the effect of the processing mark provided in the surface of the image development roll. (A)-(C) are sectional drawing and characteristic figure explaining the effect of the unevenness | corrugation of the surface of a conventional image development roll reducing. Explanatory drawing of the surface of the image development roll using the SEM photograph of the surface of an example of the column-shaped image development roll which the inventors created. Explanatory drawing using the SEM photograph which shows an example of the crystal grain boundary shape formed in the inner wall of the hollow part of the image development roll which the inventors created. Explanatory drawing using the SEM photograph which shows another example of the grain boundary shape formed in the inner wall of the hollow part of the image development roll which the inventors created. Explanatory drawing of the surface of the conventional roll which used the SEM photograph of the surface of the conventional image development roll which the inventors created using sandblasting Explanatory drawing of the surface of the conventional roll which used the SEM photograph of the surface of the conventional image development roll which the inventors created using sandblasting (A) is a perspective view showing an example of a developing roll proposed in Patent Document 1, and (B) is a perspective view showing an example of a developing roll proposed in Patent Document 2. Sectional drawing which shows a part of developing roll proposed by patent document 3 Sectional drawing explaining a toner particle slipping on the secondary fine unevenness | corrugation 7 provided in the hollow part

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Developing roll 12 Indentation part 13 Cavity part 14a, 14b Grain boundary 15 Arrow 16 Dotted line 17 Toner 18 Carrier 19 Metal pipe 20 Processing trace 21 Smooth part 22 Sand blast processing part 23 Scratch part 24 Scratch part

Claims (7)

A metal developing roll provided with a plurality of depressions having a substantially constant depth for conveying toner on the surface,
A developing roll in which a crystal grain boundary of the metal having a part or more of a substantially spherical shape or a substantially circular shape is exposed on substantially the entire inner wall of the recess. The developing roll according to claim 1, wherein the developing roll has a pipe shape, and a magnetic body is provided in a rotatable state inside the pipe. 2. The development according to claim 1, wherein an average diameter of the crystal grain boundary is 1 μm or more and 30 μm or less, and an average particle diameter of the crystal grain boundary is 20% or more and 400% or less of an average particle diameter of the toner. roll. The developing roll according to claim 1, wherein at least one of a polishing eye or a spiral cutting eye is provided in a circumferential direction of the surface of the roll. The developing roll according to claim 1, wherein the developing roll is an aluminum alloy containing at least silicon in a range of 0.20% to 0.60% or magnesium in a range of 0.45% to 0.90%. at least,
A plurality of depressions having a substantially constant depth for conveying the toner are formed on a substantially entire surface of the inner wall of the depressions of a metal roll provided on a plurality of surfaces. A developing roll that exposes the grain boundaries;
The toner conveyed using the developing roll;
An exposure roll to which the toner is transferred;
A printing apparatus. A first step of grinding or spirally cutting an outer surface of a metal pipe in a circumferential direction to form a processing mark on the outer surface;
A second step of forming an etching resist on the outer surface after the first step;
A third step of forming a plurality of depressions on the outer surface, the crystal grain boundaries of the metal being exposed on substantially the entire inner wall;
The manufacturing method of the image development roll which has.