JP2012255950A - Developing device, and image forming apparatus including the developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device including a developing roller that rotates carrying toner on the surface thereof, and a regulation member that comes into pressure-contact with the developing roller, the tip of which on the developing roller side comes into pressure-contact with the developing roller, and prevents toner from leaking from the both ends of the developing roller to the outside of the developing device, as well as an image forming apparatus including the developing device.SOLUTION: A developing roller is provided with grooves on both sides on the whole circumference in the circumferential direction.

Description

  The present invention relates to a developing device and an image forming apparatus including the developing device.

  A developing roller that carries toner on its surface and rotates about a rotation axis, and a regulating member that regulates the toner layer thickness by being pressed against the developing roller, are developed with toner that is conveyed after being regulated by the regulating member In a developing device that visualizes an electrostatic latent image on a photoconductor disposed opposite to a roller, a problem has been pointed out that toner leaks from the end of the developing roller in the longitudinal direction to the outside of the developing device.

  In order to solve such a problem, a seal member is usually disposed on the outer peripheral surface of the end portion in the longitudinal direction of the developing roller so that the toner does not leak from the end portion in the longitudinal direction of the developing roller. However, with the seal member, the toner can be blocked so as not to leak out, but the toner staying blocked by the seal member may be aggregated.

  In order to cope with such a problem, for example, in JP-A-2005-189749 (Patent Document 1), as shown in FIG. It forms at an angle with respect to the direction. As a result, the developing roller 100 rotates and the toner from the region R stays in the groove 101 before being retained in the region R where the toner is blocked by the end seal member 102. Be transported. Therefore, the toner does not stay and aggregate.

JP 2005-189749 A

  However, in the configuration of Patent Document 1, the toner does not stay in the region R, but a large number of grooves 101 are also formed in a place covered with the seal member 102, and the toner is clogged in such a place. In some cases, the toner leaks from the end of the developing roller 100 to the outside of the developing device.

  The present invention has been made in view of the above-described problems. By providing grooves at both ends of the developing roller over the entire circumference in the circumferential direction of the developing roller, development in which toner does not overflow from the both ends of the developing roller 100 to the outside of the developing device. An apparatus and an image forming apparatus including the developing device are provided.

  The present invention includes a developing roller that carries toner on its surface and rotates, and a regulating member that presses the developing roller, and a developing device that presses the tip of the regulating member on the developing roller side against the developing roller, Grooves are provided at both ends of the developing roller over the entire circumferential direction of the developing roller.

  In the present invention, it is preferable that the groove is disposed in a non-image area of the developing roller.

  In the present invention, it is preferable that a scraping member that scrapes out the toner in the groove and collects the toner in the developing device is provided.

  The present invention also provides an image forming apparatus provided with the developing device.

  According to the present invention, since the grooves are provided at both ends of the developing roller in the circumferential direction of the developing roller, the toner does not leak out of the developing device from both ends of the developing roller.

It is a schematic sectional drawing which shows the structure of the image development apparatus of this invention. It is the schematic which looked at the image development apparatus of the Example of this invention from the image development apparatus upper direction. It is a schematic sectional drawing which shows the structure of the image development apparatus of the prior art example of this invention.

  Hereinafter, a developing device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing the configuration of the developing device 1 of the present invention. In the following, the developing device of the present invention will be described, but it goes without saying that a general technique of an electrophotographic copying apparatus can be applied to other configurations.

  The developing device 1 of the present invention is a developing device that develops an electrostatic latent image by supplying toner to the electrostatic latent image on the surface of the photoreceptor 2. The developing device 1 includes a developing tank 3 that contains toner, a developing roller 4 that carries the toner and conveys the toner to the surface of the photoreceptor 2, a supply roller 5 that supplies the toner onto the developing roller 4, and a developing roller 4 A doctor blade 6 as a regulating member that regulates the toner layer thickness and a support member 7 that supports the doctor blade 6 in the developing tank 3 are included. The developing roller 4 and the supply roller 5 are rotatably provided in the developing tank 3 and are rotated counterclockwise as indicated by arrows.

  The photosensitive member 2 has a diameter of 30 mm, and the gap with the developing roller 4 disposed to face the photosensitive member 2 is set to 200 ± 20 μm by a gap holding member (not shown). The rotation direction of the photoconductor 2 was a clockwise direction indicated by an arrow, and the peripheral speed was 150 mm / sec.

  The developing tank 3 is a container member made of, for example, a hard synthetic resin and having an approximately rectangular parallelepiped appearance.

The developing roller 4 is provided with urethane rubber on the surface of a metal core (not shown), and is set to have a diameter of 16 mm, a width of 333 mm, a JIS-A hardness of 60 to 70 °, and a resistance value of 10 ⁶ Ωcm. Yes. The peripheral speed was 145 mm / sec.

  It should be noted that the toner remaining on the photosensitive member 2 without being developed at the both ends in the axial direction of the developing roller 4 is prevented from leaking out of the developing tank 3 and collected in the developing tank 3 so that both ends in the axial direction of the developing roller 4 are collected. And a scraping member w was provided in the gap in the lower part of the developing tank 3 in the vertical direction.

The supply roller 5 is provided with a porous elastic member such as urethane foam on the surface of a metal core (not shown), and slidably rubs the developing roller 4 while adsorbing toner to the holes on the surface. Thus, the toner is supplied to the developing roller 4 and the excess toner remaining on the developing roller 4 after the development is cleaned. The longitudinal direction of the portion where the supply roller 5 and the developing roller 4 face each other, that is, the width in the axial direction of the supply roller 5 is set to 333 mm. The supply roller 5 had a diameter of 14 mm, a foam density of 3 pieces / mm, an Asker C hardness of 5 °, a resistance value of 10 ⁵ Ωcm, and a peripheral speed of 145 mm / sec.

  In the present invention, a toner having a polyester resin as a main component and prepared by a pulverization method and having a volume average particle diameter of 8.5 μm is used as the toner.

  The doctor blade 6 is a plate-like member that extends parallel to the axial direction of the developing roller 4. The tip of the doctor blade 6 on the developing roller 4 side is pressed against the developing roller 4, and the other tip is provided with a support member 7 and fixed to the main body of the developing tank 3. The linear pressure that presses the doctor blade 6 against the developing roller 4 is set to 30 to 150 gf / cm. The doctor blade 6 is a thin metal plate having a spring property. The linear pressure can be changed by the thickness of the doctor blade 6. If the linear pressure is less than 30 gf / cm, the toner layer thickness on the developing roller 4 is not uniform, and sufficient charge cannot be imparted to the toner. On the other hand, when the linear pressure exceeds 150 gf / cm, the load on the toner on the developing roller 4 increases and image defects due to toner fusion occur. In the present invention, the linear pressure is 80 gf / cm. As a result, a toner layer having a constant charge is carried on the developing roller 4. The charged toner layer is supplied from the developing roller 4 to the photoconductor 2 in accordance with the potential difference between the developing roller 4 and the photoconductor 2 to develop the electrostatic latent image to form a toner image.

Examples of the material constituting the doctor blade 6 include a phosphor bronze plate, a stainless plate, and a beryllium copper plate. In the present invention, a stainless steel plate having a thickness of 0.10 mm is set to have a length of 35 mm and a longitudinal width of 297 mm. Further, the layer thickness of the toner on the developing roller 4 at this time was in the range of 0.6 to 0.8 mg / cm ² .

  FIG. 2 is a schematic view of the periphery of the developing roller 4 according to the embodiment of the present invention as viewed from above the developing device 1.

  Grooves 8 are formed at both ends of the developing roller 4 over the entire circumference of the developing roller 4 in the circumferential direction. Therefore, the leaked toner is guided to the groove 8 without being blocked. Thereafter, even if the introduced toner is likely to leak from the groove 8, the toner is collected in the developing tank 3 by the scraping member w and can be conveyed onto the developing roller 4 again.

  In addition, when the toner is blocked by the seal member, the toner is reduced in fluidity due to a load with the seal member and aggregates. However, in the present invention, since the seal member is not provided, the toner fluidity is reduced. Decreases and does not agglomerate.

  In addition, since the toner does not aggregate as described above, the toner layer thickness on the surface of the developing roller 4 becomes uniform, and image fogging and uneven density are not generated on the output image.

  Further, since the groove 8 is disposed in the non-image area of the developing roller 4, the toner does not scatter on the output image.

  The shape of the groove 8 is concave, V-shaped, U-shaped, etc., and the depth and width are not particularly limited. As a means for forming the groove 8, a generally used grinding process, a cutting process using a diamond cutter or the like, an etching process using a chemical agent, or the like can be used.

DESCRIPTION OF SYMBOLS 1 Developing device 2 Photoconductor 3 Developing tank 4 Developing roller 5 Supply roller 6 Doctor blade 7 Support member 8 Groove w Scraping member

Claims (4)

In a developing device comprising a developing roller that carries toner on its surface and rotates, and a regulating member that presses the developing roller, and the tip of the regulating member on the developing roller side is pressed against the developing roller.
A developing device characterized in that grooves are provided at both ends of the developing roller over the entire circumference in the circumferential direction of the developing roller.   The developing device according to claim 1, wherein the groove is disposed in a non-image area of the developing roller.   The developing device according to claim 1, wherein the developing device is provided with a scraping member that scrapes the toner in the groove and collects the toner in the developing device.   An image forming apparatus comprising the developing device according to claim 1.