JP2007316203A - Electrophotogrpahic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that prevents charging noise absorption performance from degrading due to inertial force or environmental temperature changes. <P>SOLUTION: The electrophotographic photoreceptor includes: a photoreceptor drum; a cylindrical tubular member 1 made from resin, which is inserted in the photoreceptor drum and has a slit 2 extending parallel to its axis from one end to the other end; and a spring made of metal, which is incorporated in the cylindrical member 1 and presses the cylindrical member 1 in firm contact with the internal face of the photoreceptor drum. A plurality of ribs 3 are formed on the inner peripheral face of the cylindrical member 1 made of resin to extend parallel to the axis. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic photoreceptor (hereinafter, also simply referred to as “photoreceptor”), and more specifically, a resin cylindrical member is used in order to provide charging noise (noise) absorption performance in a contact-type charging device. The present invention relates to a built-in cylindrical electrophotographic photoreceptor.

  Conventionally, a contact-type charging device has been widely used as a charging device in an electrophotographic image forming apparatus. A contact-type charging device is a device in which a charging member to which a high voltage is applied is directly brought into contact with the surface of a photoreceptor for electrophotography to charge a photosensitive layer, and a roller method or a brush method is applied to the charging member. .

  Advantages of the contact method include significantly less generation of ozone compared to a non-contact type corona discharge charging device, and a relatively simple and compact design of the device structure.

  On the other hand, one of the problems of the contact charging device is noise generated during the charging operation. In the case of the contact charging method, as the voltage applied to the charging member, an appropriate alternating current is superimposed on the basic direct current to improve the uniformity of charging on the surface of the photoreceptor. However, it is known that by superimposing alternating current, vibration corresponding to the frequency of the applied alternating voltage is generated between the charging member and the photosensitive member, resulting in noise (Patent Document 1).

  Conventionally, as a method for suppressing the charging noise, there is known a method of arranging a member having sound absorption performance inside a photosensitive drum (Patent Documents 2 to 5).

  FIG. 6 is a cross-sectional view showing a conventional resin cylindrical member 11 having sound absorption performance. The resin cylindrical member 11 shown in the figure is provided with slits 12 and grooves 13 in the axial direction. The resin member is provided with a spring property, and this spring property is used to press and fix the inner surface of the photosensitive drum. It is a mechanism to be done. However, since the spring property of the resin member is not strong, there is a problem that the pressing force is insufficient due to a strong inertia force or a change in environmental temperature, and the resin cylindrical member 11 moves in the photosensitive drum. In order to avoid it, it was necessary to fix with an adhesive or the like.

On the other hand, the present applicant has proposed a resin cylindrical member 21 having a cross-sectional structure shown in FIG. 7 (Patent Document 6). A resin-made cylindrical member 21 having a slit 22 in the illustrated axial direction has a built-in metal spring 24. Due to the strong pressing force against the inner surface of the photosensitive drum due to the action of the metal spring 24, the resin-made cylindrical shape is formed. The member 21 is fixed. In this case, since the spring property of the metal spring 24 is strong, the pressing force of the resin cylindrical member 21 is maintained at a certain level or more even by inertial force or environmental temperature fluctuation, and the resin cylindrical member 21 is exposed to light. It does not move inside the drum, and fixing with an adhesive or the like is not necessary.
Japanese Patent Laid-Open No. 4-86682 JP-A-5-35166 JP-A-5-35167 JP-A-5-35048 JP-A-8-54804 JP 2000-321929 A

  As described above, by using the resin cylindrical member 21 to which the metal spring 24 described in Patent Document 6 is mounted, the pressing force is maintained at a certain level or more even by inertial force or environmental temperature fluctuation, and the photosensitive drum. It has become possible to suppress internal movement, but it turns out that it is still not enough. That is, in the resin cylindrical member 21 to which the metal spring 24 is attached, since a force directed outward is applied only to the portion where the metal spring 24 is pressed, the outer diameter of only the portion increases as shown in FIG. As a result, it was found that the contact area with the inside of the photosensitive drum was reduced and the noise suppression effect was reduced. Also, if the pressing force of the metal spring is too large, the photosensitive drum is deformed and the outer diameter becomes large. On the other hand, if the pressing force of the metal spring is too small, the resin cylindrical member is detached due to leaving the environment. Since there is a problem, it has been desired to realize a photoconductor that is not affected only by the pressing force of the metal spring.

  In order to prevent a change in the outer diameter of the resin cylindrical member 21 at the contact portion with the metal spring 24, it is possible to simply increase the thickness of the resin cylindrical member 21, but when the thickness increases, The entire resin cylindrical member 21 is not easily deformed by the spring action of the metal spring 24, and the effect itself of the metal spring 24 is diminished, and as a result, the resin cylindrical shape in the photosensitive drum. It has been unavoidable that the holding force of the member 21 becomes small.

  Accordingly, an object of the present invention is to provide an electrophotographic photosensitive member having a resin cylindrical member with a built-in metal spring, in which partial deformation of the resin cylindrical member is suppressed, and the inner surface of the photosensitive drum and the resin By increasing the contact area with the outer surface of the cylindrical member so that the pressing force is maintained at a certain level or more even by inertial force or environmental temperature fluctuation, the charged sound absorbing performance is improved.

  As a result of intensive studies to solve the above problems, the present inventors have reached the following findings. That is, when a metal spring is inserted into a resin cylindrical member, the pressing force of the metal spring is transmitted to the resin cylindrical member only at the contact portion. Since the material has distortion with respect to the outer surface shape of the metal spring, the transmission of force to the resin cylindrical member tends to be uneven depending on the location. With respect to this problem, the present inventors limit the contact point between the metal spring and the resin cylindrical member so that the pressing force toward the outer surface by the metal spring can be reduced to the resin cylindrical member, and thus the photosensitive drum. The present invention has been completed by finding that it can be transmitted uniformly, and that the above problem can be solved.

That is, the electrophotographic photosensitive member of the present invention includes a photosensitive drum, a resin-made cylindrical member that is inserted into the photosensitive drum and has a slit extending between both ends in parallel to the axial direction, and the resin-made photosensitive member. In an electrophotographic photoreceptor comprising a metal spring that is built in a cylindrical member and presses the resin cylindrical member against the inner surface of the photosensitive drum,
A plurality of ribs extending in parallel to the axial direction are provided on the inner peripheral surface of the resin cylindrical member.

  In the present invention, a plate spring, a C-shaped ring, or a coil spring having a C-shaped cross section perpendicular to the axial direction can be suitably used as the metal spring.

  In the present invention, the number of the plurality of ribs is preferably 3 to 12, and the plurality of ribs are arranged at equal intervals on the inner peripheral surface of the resin cylindrical member. It is preferable. Furthermore, it is preferable that the cross-sectional shape perpendicular | vertical to the axial direction of these ribs makes the trapezoid narrowed toward the central axis.

  According to the present invention, by providing a plurality of ribs on the inner peripheral surface of the resin cylindrical member, partial deformation of the resin cylindrical member containing the metal spring is suppressed, and the inner surface of the photosensitive drum and the resin are suppressed. The contact area with the outer surface of the cylindrical member is improved, and the pressing force can be maintained above a certain level due to inertial forces and environmental temperature fluctuations. It has become possible to realize a photographic photoreceptor. Therefore, according to the present invention, it is possible to obtain a photoreceptor that is more excellent in resistance to environmental fluctuations and the like than in the past.

Hereinafter, specific embodiments of the electrophotographic photoreceptor of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic cross-sectional view of an example of the electrophotographic photoreceptor of the present invention. As shown in the figure, the photoreceptor of the present invention includes a photosensitive drum 10, a resin cylindrical member 1 fitted into the photosensitive drum 10, and a resin cylindrical member 1 incorporated in the resin cylindrical member 1. And a metal spring 4 that presses the inner surface of the photosensitive drum 10 against the inner surface of the photosensitive drum 10.

  FIG. 2 shows a cross-sectional view (a) perpendicular to the axial direction and a perspective view (b) showing a preferred example of the resin cylindrical member 1 according to the present invention. As shown in the drawing, the resin cylindrical member 1 according to the present invention is provided with a slit 2 extending between both ends in parallel to the axial direction so that a cross section perpendicular to the axial direction is C-shaped. ing. Thereby, the resin cylindrical member 1 is fixed by the pressing force with the inner surface of the photosensitive drum 10 due to the spring property of the resin member. The material and thickness of the resin used for the resin cylindrical member 1 and the width of the slit 2 can be configured in the same manner as known members used for the same purpose, and are not particularly limited. No (see Patent Document 6).

  Further, in the present invention, as shown in the drawing, it is important that a plurality of ribs 3 extending in parallel to the axial direction, preferably extending between both ends, are provided on the inner peripheral surface of the resin cylindrical member 1. It is. By providing the rib 3 on the inner peripheral surface of the resin cylindrical member 1, when the metal spring 4 is built in, the pressing force is not only the contact portion but also the longitudinal direction of the resin cylindrical member 1. As a result, the whole is spread. Thereby, the expansion of the outer diameter of the portion with which the metal spring 4 abuts can be suppressed, and the reduction of the contact area between the inner surface of the photosensitive drum 10 and the outer surface of the resin cylindrical member 1 can be prevented. The outer diameter of the entire resin cylindrical member can be enlarged by the spring 4 so that it can contact the inner surface of the photosensitive drum with a uniform force. As a result, a photosensitive member is obtained in which the pressing force is maintained at a certain level or more even by an inertial force or an environmental temperature fluctuation, and the charging sound absorbing performance can be stably improved.

  The number and dimensions of the ribs 3 are not particularly limited as long as partial deformation of the resin cylindrical member 1 due to the action of the metal spring 4 can be suppressed, but the deformation suppressing effect and the weight increase. From the viewpoint of prevention, the number is preferably 3 to 12. Moreover, it is suitable to arrange | position the rib 3 at equal intervals on the internal peripheral surface of the resin-made cylindrical members 1 from a viewpoint of obtaining a deformation | transformation suppression effect more favorably. Further, the cross-sectional shape of the rib 3 is narrowed toward the central axis of the resin-made cylindrical member 1 as illustrated from the viewpoint of ease of arrangement of the metal spring 4 and durability of the rib 3 itself. It is preferable to use a trapezoidal shape or a kamaboko shape (not shown). Such rib 3 can be easily formed by integral molding.

  FIG. 3 shows a perspective view of an example of the metal spring 4 used in the present invention. 4 and 5 are a cross-sectional view perpendicular to the axial direction and a partially transparent perspective view showing the resin cylindrical member 1 in which the metal spring 4 is incorporated.

  The metal spring 4 incorporated in the resin cylindrical member 1 imparts a strong pressing force against the inner surface of the photosensitive drum 10 to the resin cylindrical member 1 due to its expansion action. As the metal spring 4 having such an expanding action, a leaf spring, a C-shaped ring, or a coiled spring having a C-shaped cross section perpendicular to the axial direction can be preferably exemplified. In the present invention, as described above, by providing the rib 3 on the inner peripheral surface of the resin cylindrical member 1, even if the metal spring 4 is incorporated, only the portion of the resin cylindrical member 1 is expanded. The resin cylindrical member 1 is uniformly expanded and the slit width is expanded.

Hereinafter, the present invention will be specifically described based on examples.
(Outer diameter deformation evaluation)
Resin cylindrical member 1 provided with slits 2 and ribs 3 shown in FIG. 2 (made of polypropylene, outer diameter 28.0 mm, length 100 mm, number of ribs: 8 (equally spaced), rib shape: center axis A metal leaf spring 4 (made of stainless steel, plate thickness 0.5 mm, length 15 mm) shown in FIG. 3 was inserted into the trapezoid narrowed toward the side to form a member A (see FIGS. 4 and 5). As shown in FIG. 7, a member B is formed by inserting a similar plate spring 24 into a conventional cylindrical resin member 21 (polypropylene, outer diameter 28.0 mm, length 100 mm). The non-resin-made cylindrical member 21 was designated as member C for comparison. In both members A and B, no adhesive was used between the resin cylindrical member and the leaf spring.

  Table 1 below shows a comparison of the deformation amount of the outer diameter of the resin cylindrical member after the members A and B are left in a normal temperature (23 ° C., 50% RH) environment for 24 hours.

  From the results of Table 1 above, it is confirmed that the member A can be adhered to the photosensitive drum over a wide area without changing the outer diameter between the end portion and the leaf spring contact position even after being left at room temperature. It was.

(Retention force evaluation)
Next, each member A and B is inserted into a photosensitive drum (with an organic photosensitive layer formed on the surface of an aluminum pipe, an outer diameter of 30 mm, and a length of 260.5 mm) to produce a photoconductor, and room temperature (23 ° C. 50 % RH), low temperature (−20 ° C., 20% RH), and high temperature (50 ° C., 40% RH), and then the holding power of each member was evaluated. The holding force was evaluated based on whether or not the member moved by applying a force of 9.8 N (1 kgf) in the axial direction to the members A and B in the photosensitive drum. The results are shown in Table 2 below.

  As shown in Table 2 above, the member A did not move even when a force was applied after being left in any environment of normal temperature, low temperature, and high temperature. On the other hand, the member B has moved by applying a force after being left in a high temperature environment.

(Noise measurement)
Each member A and B is inserted into a photosensitive drum (with an organic photosensitive layer formed on the surface of an aluminum pipe, an outer diameter of 30 mm, a length of 260.5 mm) to produce a photoconductor, and at room temperature (23 ° C., 50% RH) The noise suppression effect after being left in each environment of low temperature (−20 ° C., 20% RH) and high temperature (50 ° C., 40% RH) was evaluated. The evaluation was performed by incorporating each photoconductor into an image forming apparatus using a contact charging method and measuring noise during charging in a noiseless room. The noise measuring device was installed at a certain location about 50 cm away from the image forming apparatus. In order to quantify the noise, the magnitude (dB) of the driving sound of the image forming apparatus measured from the magnitude of the noise (dB) at the time of charging, with the voltage applied to the charging roller being cut and without any charging noise. The subtraction was defined as the magnitude of charging noise. If this charging noise is 3 dB or less, it is at a level with no problem in use. The results are shown in Table 3 below.

  As a result, the effect of noise suppression was higher in the photoconductor using member A than in the photoconductor using member B. This is presumably because the member A has a larger contact area with the photosensitive drum than the member B and is held with a larger force even when the pressing force by the leaf spring is the same. Further, as shown in Table 3 above, the noise of the member B increased after being left in the high temperature environment, but this phenomenon was not confirmed in the member A. This is because the contact area of the member B with respect to the photosensitive drum is smaller than that of the member A, so that the member B is deformed by being left in a high temperature environment, the pressing force is insufficient, and the noise suppression effect is reduced. .

It is a schematic sectional drawing which shows an example of the electrophotographic photoreceptor of this invention. It is (a) sectional drawing perpendicular | vertical to an axial direction and (b) perspective view which show an example of the resin-made cylindrical members which concern on this invention. It is a perspective view which shows an example of metal springs. It is sectional drawing perpendicular | vertical to the axial direction which shows the state which inserted the metal spring in the resin-made cylindrical members based on this invention. It is a partially transparent perspective view which shows the state which inserted the metal spring in the resin-made cylindrical members which concern on this invention. It is sectional drawing perpendicular | vertical to the axial direction which shows the conventional resin cylindrical member. It is sectional drawing perpendicular | vertical to the axial direction which shows the state which inserted the metal spring in the other conventional resin cylindrical member. It is explanatory drawing which shows the outer-diameter deformation | transformation of the resin-made cylindrical member by insertion of a metal spring in the cross section parallel to an axial direction.

Explanation of symbols

1,11,21 Resin cylindrical member 2,12,22 Slit 3 Rib 4,24 Metal spring 10 Photosensitive drum 13 Groove

Claims (7)

A photosensitive drum, a resin cylindrical member fitted into the photosensitive drum and having a slit extending between both ends parallel to the axial direction, and the resin cylindrical member built in the resin cylindrical member; An electrophotographic photoreceptor comprising a metal spring that presses a member against the inner surface of the photosensitive drum;
An electrophotographic photoreceptor, wherein a plurality of ribs extending in parallel to the axial direction are provided on an inner peripheral surface of the resin cylindrical member.   2. The electrophotographic photoreceptor according to claim 1, wherein the metal spring is a leaf spring having a C-shaped cross section perpendicular to the axial direction.   2. The electrophotographic photoreceptor according to claim 1, wherein the metal spring is a C-shaped ring.   2. The electrophotographic photoreceptor according to claim 1, wherein the metal spring is a coil spring.   5. The electrophotographic photoreceptor according to claim 1, wherein the number of the plurality of ribs is 3 to 12. 5.   The electrophotographic photoreceptor according to claim 1, wherein the plurality of ribs are arranged at equal intervals on an inner peripheral surface of the resin cylindrical member.   The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein a cross-sectional shape perpendicular to the axial direction of the plurality of ribs forms a trapezoid narrowing toward the central axis.

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