Patent Description:
In an electrophotographic image forming apparatus that uses a process cartridge system, when a cartridge is attached to the apparatus main body, an electrode member of the cartridge is in contact with a main body electrode of the apparatus main body, thereby electrically connecting a conduction-target member, such as a process unit, of the cartridge to the apparatus main body. As an example of the electrode member, <CIT> discloses a configuration in which conductive resin is incorporated in the frame of a cartridge.

However, in the above-mentioned conventional example, since the conductive portion, which may be conductive resin or metal plate, for example, is attached to the frame, the frame needs to be made of a resin with high flame retardant function (flame-retardant material) in order to ensure electrical safety in the vicinity of the conductive portion. The use of flame-retardant material limits the choice of materials. This poses challenges particularly to the weight reduction of the frame components.

<CIT> shows a generic cartridge for an image forming apparatus, the cartridge comprising: a process unit to be used to form an image; a first member including a first resin material; a second member including a second resin material having higher flame retardant capability than the first resin material; and an electrode member including a contact section configured to be supplied with power from an apparatus main body of the image forming apparatus, the electrode member being configured to electrically connect the apparatus main body to the process unit, wherein the contact section is located in a vicinity of the first and second members.

It is the object of the present invention to further develop a cartridge for an image forming apparatus according to the preamble of claim <NUM> such that it achieves both weight reduction and safety of a frame for supporting a process unit.

The object of the present invention is achieved by a cartridge for an image forming apparatus having the features of claim <NUM>.

Further developments of the present invention are defined in the dependent claims.

According to the present invention, it is possible to achieve both the weight reduction and safety of a frame that supports a process unit.

The above and further features, advantages and effects of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Hereinafter, a description will be given, with reference to the drawings, of embodiments (examples) of the present invention. However, the sizes, materials, shapes, their relative arrangements, or the like of constituents described in the embodiments may be appropriately changed according to the configurations, various conditions, or the like of apparatuses to which the invention is applied. Therefore, the sizes, materials, shapes, their relative arrangements, or the like of the constituents described in the embodiments do not intend to limit the scope of the invention to the following embodiments.

Referring to drawings, an embodiment of the present invention is now described in detail. A direction along the rotation axis of an electrophotographic photosensitive drum is referred to as a longitudinal direction. In the longitudinal direction, the side on which the electrophotographic photosensitive drum receives a driving force from the image forming apparatus main body is referred to as a drive side, and the opposite side is referred to as a non-drive side. Referring to <FIG> and <FIG>, the overall configuration and an image formation process are now described. <FIG> is a cross-sectional view of an apparatus main body (electrophotographic image forming apparatus main body, image forming apparatus main body) A and a process cartridge B of an electrophotographic image forming apparatus of one embodiment according to the present invention. <FIG> is a cross-sectional view of the process cartridge B. The process cartridge is formed by integrating a photosensitive member and a process unit which acts on the photosensitive member, into a cartridge. The process cartridge is attached to the electrophotographic image forming apparatus main body in a detachable manner. For example, the process cartridge may be formed by integrating a photosensitive member and at least one of a developing unit, a charging unit, and a cleaning unit as a process unit into a cartridge. The electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming method. Examples of the electrophotographic image forming apparatus include an electrophotographic copier, an electrophotographic printer (e.g., an LED printer and laser beam printer), a facsimile machine, and a word processor. The apparatus main body A is the portion of the electrophotographic image forming apparatus excluding the process cartridge B (hereinafter, referred to as cartridge B).

The electrophotographic image forming apparatus (image forming apparatus) shown in <FIG> is a laser beam printer using an electrophotographic technique in which the cartridge B is attached to the apparatus main body A in a detachable manner. When the cartridge B is attached to the apparatus main body A, an exposure apparatus <NUM> (laser scanner unit) is arranged that forms latent images on an electrophotographic photosensitive drum <NUM>, which serves as an image bearing member of the cartridge B. A sheet tray <NUM>, which is arranged under the cartridge B, stores recording media (hereinafter referred to as sheet material PA) on which images are formed. The electrophotographic photosensitive drum <NUM> is a photosensitive member (electrophotographic photosensitive member) used to form electrophotographic images. The apparatus main body A further includes a pickup roller 5a, a pair of feeding rollers 5b, a transfer guide <NUM>, a transfer roller <NUM>, a transport guide <NUM>, a fixing apparatus <NUM>, a pair of discharge rollers <NUM>, and a discharge tray <NUM>, which are arranged along the transport direction D of the sheet material PA. The fixing apparatus <NUM> includes a heating roller 9a and a pressing roller 9b.

The outline of the image formation process is now described. In response to a print start signal, the electrophotographic photosensitive drum (hereinafter, referred to as photosensitive drum <NUM> or simply as drum <NUM>) is driven to rotate in the direction of arrow R at a predetermined circumferential speed (process speed). A charging roller (charging member) <NUM>, to which a bias voltage is applied, is in contact with the outer circumferential surface of the drum <NUM> and uniformly charges the outer circumferential surface of the drum <NUM> (see <FIG>). The exposure apparatus <NUM> outputs a laser beam L according to image information. The laser beam L passes through a laser opening <NUM> (see <FIG>) provided in a cleaning frame <NUM> of the cartridge B, and scans the outer circumferential surface of the drum <NUM> to perform exposure. An electrostatic latent image corresponding to the image information is thus formed on the outer circumferential surface of the drum <NUM>.

As shown in <FIG>, a developing unit <NUM>, which serves as the developing apparatus, includes a toner chamber <NUM> storing toner T. A transport member (agitation member) <NUM> rotates to agitate and transport the toner T to a toner supply chamber <NUM>. The magnetic force of a magnet roller <NUM> (stationary magnet) holds the toner T on the surface of a developing roller <NUM>. The developing roller <NUM> is a developer carrying member that carries developer (toner T) on its surface to develop the latent image formed on the drum <NUM>. A development blade <NUM> friction-charges the toner T and controls the layer thickness of the toner T on the circumferential surface of the developing roller <NUM>, which serves as the developer carrying member.

The toner T is supplied to the drum <NUM> according to the electrostatic latent image and develops the latent image. As a result, the latent image is formed as a visible toner image. The drum <NUM> is an image bearing member that bears a latent image or an image to be formed with toner (toner image, developer image) on its surface. As shown in <FIG>, the sheet material PA stored in a lower part of the apparatus main body A is sent out from the sheet tray <NUM> by the pickup roller 5a and the pair of feeding rollers 5b in time with the output of a laser beam L. The sheet material PA is transported along the transfer guide <NUM> to the transfer position between the drum <NUM> and the transfer roller <NUM>. At this transfer position, the toner image is sequentially transferred from the drum <NUM> to the sheet material PA.

The sheet material PA to which the toner image is transferred is transported away from the drum <NUM> and to the fixing apparatus <NUM> along the transport guide <NUM>. The sheet material PA then passes through the nip portion of the heating roller 9a and the pressing roller 9b of the fixing apparatus <NUM>. The fixing process of pressing and heating at the nip portion fixes the toner image on the sheet material PA. The sheet material PA that has undergone the toner image fixing process is transported to the pair of discharge rollers <NUM> and discharged to the discharge tray <NUM>.

As shown in <FIG>, the residual toner on the outer circumferential surface of the drum <NUM> after transferring is removed by a cleaning member <NUM> and used for an image formation process again. The toner removed from the drum <NUM> is stored in a waste toner chamber 71b of a toner cleaning unit <NUM>. The cleaning unit <NUM> is a photosensitive drum unit including the photosensitive drum <NUM>. In the foregoing description, the charging roller <NUM>, the developing roller <NUM>, the transfer roller <NUM>, and the cleaning member <NUM> function as a process unit for acting on the drum <NUM>.

Referring to <FIG>, <FIG>, and <FIG>, the overall configuration of the cartridge B is now described. <FIG> is a cross-sectional view of the cartridge B, and <FIG> and <FIG> are perspective views illustrating the configuration of the cartridge B. In this embodiment, the description of the screws for connecting parts is omitted. The cartridge B includes the cleaning unit (photosensitive member holding unit, drum holding unit, image bearing member holding unit, first unit) <NUM> and the developing unit (developer carrying member holding unit, second unit) <NUM>.

As shown in <FIG>, the cleaning unit <NUM> includes the drum <NUM>, the charging roller <NUM>, the cleaning member <NUM>, and a cleaning frame <NUM>, which supports these components. On the drive side, the drum <NUM> includes a drive-side drum flange <NUM>, which is rotationally supported by a hole section 73a of a drum bearing <NUM> (see <FIG>). In a broad sense, the drum bearing <NUM> and the cleaning frame <NUM> can be collectively referred to as a cleaning frame. As shown in <FIG>, on the non-drive side, a drum shaft <NUM> is press-fitted into a hole section 71c formed in the cleaning frame <NUM> so that a hole section (not shown) of the non-drive-side drum flange is rotationally supported.

The drum flanges are portions that are rotationally borne and supported by the respective bearing portions. As shown in <FIG>, the charging roller <NUM> and the cleaning member <NUM> of the cleaning unit <NUM> are in contact with the outer circumferential surface of the drum <NUM>. The cleaning member <NUM> has a rubber blade 77a, which is a blade-shaped elastic member made of rubber as an elastic material, and a support member 77b supporting the rubber blade. The rubber blade 77a substantially extends in the direction opposite to the rotation direction of the drum <NUM> and is in contact with the drum <NUM>. That is, the rubber blade 77a is in contact with the drum <NUM> with its distal edge pointing toward the upstream side in the rotation direction R of the drum <NUM>. The waste toner removed from the surface of the drum <NUM> by the cleaning member <NUM> is stored in the waste toner chamber 71b defined by the cleaning frame <NUM> and the cleaning member <NUM>.

As shown in <FIG>, a scooping sheet <NUM> for preventing waste toner from leaking from the cleaning frame <NUM> is provided at an edge of the cleaning frame <NUM> in contact with the drum <NUM>. The charging roller <NUM> is rotationally attached to the cleaning unit <NUM> through charging roller bearings <NUM> located at opposite ends in the longitudinal direction of the cleaning frame <NUM>. The longitudinal direction of the cleaning frame <NUM> (the longitudinal direction of the cartridge B) is substantially parallel to the direction in which the rotation axis of the drum <NUM> extends (axial direction). Hereinafter, the longitudinal direction and the axial direction therefore refer to the axial direction of the drum <NUM> unless otherwise specified. Urging members <NUM> press the charging roller bearings <NUM> toward the drum <NUM>, thereby pressing the charging roller <NUM> against the drum <NUM>. The charging roller <NUM> is driven and rotated by the rotation of the drum <NUM>.

As shown in <FIG>, the developing unit <NUM> includes the developing roller <NUM>, a developer container <NUM> supporting the developing roller <NUM>, and a development blade <NUM>. The developing roller <NUM> is rotationally attached to the developer container <NUM> through bearing members <NUM> (<FIG>) and <FIG> (<FIG>) provided at opposite ends. The developing roller <NUM> contains the magnet roller <NUM>. The developing unit <NUM> includes the development blade <NUM> for controlling the toner layer on the developing roller <NUM>. As shown in <FIG> and <FIG>, spacing members <NUM> are attached to opposite ends of the developing roller <NUM>. The spacing members <NUM> are brought into contact with the drum <NUM>, so that the developing roller <NUM> is held with a small gap created between the developing roller <NUM> and the drum <NUM>. As shown in <FIG>, a spout prevention sheet <NUM> for preventing the toner from leaking from the developing unit <NUM> is provided at an edge of the developer container <NUM> and in contact with the developing roller <NUM>. A transport member <NUM> is provided in the toner chamber <NUM> defined by the developer container <NUM> and a base member <NUM>. The transport member <NUM> agitates the toner stored in the toner chamber <NUM> and transports the toner to the toner supply chamber <NUM>.

As shown in <FIG> and <FIG>, the cartridge B is formed by combining the cleaning unit <NUM> and the developing unit <NUM>. To join the developing unit <NUM> to the cleaning unit <NUM>, the center of a first developing-side support boss 26a of the bearing member <NUM> is aligned with a first suspension hole 71i on the drive side of the cleaning frame <NUM>, and the center of a second developing-side support boss 27a of the bearing member <NUM> is aligned with a second suspension hole 71j on the non-drive side. Specifically, the developing unit <NUM> is moved in the direction of arrow G so that the first and second developing-side support bosses 26a and 27a are fitted into the first and second suspension holes 71i and 71j. The developing unit <NUM> is thus movably connected to the cleaning unit <NUM>. Specifically, the developing unit <NUM> is rotationally (pivotally) connected to the cleaning unit <NUM>. That is, the developing roller <NUM> is coupled to the drum <NUM> so as to be movable toward and away from the drum <NUM>. Then, the drum bearing <NUM> is coupled to the cleaning unit <NUM> to form the cartridge B.

In this embodiment, a non-drive-side urging member <NUM> (<FIG>) and a drive-side urging member 46R (<FIG>) are compression springs. The urging force of the springs allows the drive-side urging member 46R and the non-drive-side urging member <NUM> to urge the developing unit <NUM> to the cleaning unit <NUM>, ensuring that the developing roller <NUM> is pressed in the direction of the drum <NUM>. The present embodiment also includes the spacing members <NUM> at opposite ends of the developing roller <NUM>. That is, the drum <NUM> is in contact with the developing roller <NUM> through the spacing members <NUM> with a predetermined contact pressure, so that the developing roller <NUM> is held with a predetermined gap created between the developing roller <NUM> and the drum <NUM>. The relative positions of these components are thus determined.

Referring to <FIG>, <FIG>, the attachment of the cartridge B is now specifically described. <FIG> is a cross-sectional view of the drive-side guide portion of the image forming apparatus A for illustrating the attachment of the cartridge B. <FIG> is a cross-sectional view of the non-drive-side guide portion of the image forming apparatus A for illustrating the attachment of the cartridge B. <FIG> is a cross-sectional view of the drive side of the image forming apparatus A for illustrating the positioning of the cartridge B. <FIG> is a cross-sectional view of the non-drive side of the image forming apparatus A for illustrating the positioning of the cartridge B.

The cartridge B is attached as follows. As shown in <FIG>, a first drive-side plate <NUM> includes an upper guide rail <NUM> and a guide rail <NUM> as guides, and a non-drive-side plate <NUM> includes an upper guide rail 16d and a guide rail 16e. The drum bearing <NUM> provided on the drive side of the cartridge B has a rotation stop target portion 73c. The cartridge B is attached in a direction (arrow C) substantially perpendicular to the axis of the drum <NUM> (<FIG>).

The cleaning frame <NUM> includes, on the non-drive side in the longitudinal direction, a positioning target portion 71d as a first positioning portion and a rotation stop target portion 71f as a second positioning portion. When the cartridge B is attached through a cartridge insertion slot <NUM> of the apparatus main body A, the guide rail <NUM> of the apparatus main body A guides the rotation stop target portion 73c of the cartridge B on the drive side of the cartridge B. On the non-drive side of the cartridge B, the guide rails 16d and 16e of the apparatus main body A guide the positioning target portion 71d and the rotation stop target portion 71f of the cartridge B. The cartridge B is thus attached to the apparatus main body A.

The closing of an opening/closing door <NUM> is now described. As shown in <FIG>, <FIG>, the first drive-side plate <NUM> has an upper positioning portion 15a, a lower positioning portion 15b, and a rotation stop portion 15c as positioning portions, and the non-drive-side plate <NUM> has a positioning portion 16a and an upper rotation stop portion 16c. The drum bearing <NUM> includes an upper positioning target portion (first positioning target portion, first protrusion, first bulging portion) 73d and a lower positioning target portion (second positioning target portion, second protrusion, second bulging portion) 73f.

Cartridge pressing members <NUM> and <NUM> are rotationally attached to opposite axial ends of the opening/closing door <NUM>. Cartridge pressing springs <NUM> and <NUM> are attached to the longitudinal ends of the front plate of the image forming apparatus A. The drum bearing <NUM> has a pressing target portion 73e as an urging force receiving portion, and the cleaning frame <NUM> has a pressing target portion 71o on the non-drive side (see <FIG>). When the opening/closing door <NUM> is closed, the cartridge pressing members <NUM> and <NUM> urged by the cartridge pressing springs <NUM> and <NUM> of the apparatus main body A press the pressing target portions 73e and 71o of the cartridge B (see <FIG>).

As a result, on the drive side, the upper positioning target portion 73d, the lower positioning target portion 73f, and the rotation stop target portion 73c of the cartridge B are fixed to the upper positioning portion 15a, the lower positioning portion 15b, and the rotation stop portion 15c, respectively, of the apparatus main body A. The cartridge B and the drum <NUM> are thus positioned on the drive side. Likewise, on the non-drive side, the positioning target portion 71d and the rotation stop target portion 71f of the cartridge B are fixed to the positioning portion 16a and the rotation stop portion 16c, respectively, of the apparatus main body A. The cartridge B and the drum <NUM> are thus positioned on the non-drive side.

The above description of an example of the configuration for positioning the cartridge B relative to the apparatus main body A is not intended to limit the means for positioning. A configuration may be used that directly acts on the positioning target portion 73d and the rotation stop target portion 73f on the drive side of the cartridge B, and the positioning target portion 71d and the rotation stop target portion 71f on the non-drive side to fix the positioning portions.

Referring to <FIG>, <FIG>, the configuration in which the cartridge B receives a driving force from the apparatus main body A is now described. <FIG> is a diagram showing the configuration of a drive portion of the apparatus main body A. <FIG> is a diagram showing the configuration of a drive portion of the cartridge B. <FIG> is a diagram showing a state before the drive portions of the apparatus main body A and the cartridge B are engaged. <FIG> is a diagram showing a state in which the power of the apparatus main body A is turned on and the drive portions of the apparatus main body A and the cartridge B are engaged.

As shown in <FIG>, the apparatus main body A includes a drive transmission member <NUM>, which receives a driving force from a driving source (not shown) of the apparatus main body A and transmits the driving force to the cartridge B. As shown in <FIG>, the cartridge B includes a driven portion 63b in the drive-side drum flange <NUM> to engage with the drive transmission member <NUM> and receive the driving force. When the opening/closing door <NUM> is closed and the power of the apparatus main body A is turned on, the drive transmission member <NUM> moves in the direction of arrow E in <FIG>. Then, as shown in <FIG>, a drive transmission portion 81b of the drive transmission member <NUM> engages with the driven portion 63b of the drive-side drum flange <NUM>, and the drum <NUM> is rotated through the drive-side drum flange <NUM>. The outer circumference of the drive transmission member <NUM> has a gear shape <NUM>. Additionally, a developing roller gear <NUM> is coupled to an end of the developing roller <NUM> of the cartridge B. When the driven portion 63b of the drive-side drum flange <NUM> is engaged as shown in <FIG>, the gear shape <NUM> on the drive transmission member <NUM> and the developing roller gear <NUM> are arranged so as to mesh with each other. That is, when the drive transmission member <NUM> rotates the drum <NUM> through the drive-side drum flange, the developing roller <NUM> also rotates simultaneously through the developing roller gear <NUM>.

Referring to <FIG>, <FIG>, <FIG>, the development contact configuration, which is a feature of the present embodiment, of the cartridge B is now described. <FIG> is an exploded perspective view of the developing unit <NUM> showing the key components of the development contact configuration extracted. <FIG> is a perspective view of the cartridge B, <FIG> is a side view of the cartridge B for illustrating the development contact configuration, and <FIG> is an enlarged cross-sectional view of the area around the development contact taken along line I-I in <FIG>.

As shown in <FIG>, the developing unit <NUM> includes a developer container <NUM>, which serves as a first frame (a first member), and a developing roller <NUM>, which serves as a process unit. The developer container <NUM> is made of a material(a first resin material) having a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of HB according to the UL94 standard. It is known that adding an additive to a resin material, which generally has the property of igniting in contact with flame, can render the resin flame retardant. When an additive is added to one type of resin material, a higher flame-retardant effect results in a greater specific gravity of the resin. This causes a problem that the weight of the necessary resin material in the entire product is increased, causing a greater load on the environment. In this embodiment, the developer container <NUM> is made of a material that is free of such an additive and has a low density. The developing roller <NUM> has the function of carrying developer by receiving a predetermined bias. The developing roller <NUM> is rotationally supported as a rotating member by the developer container <NUM> through the bearing member <NUM> (see <FIG>) on the drive side and a conductive bearing member <NUM> and the bearing member <NUM> on the non-drive side.

The flame retardant capability is now described. In the present embodiment, the UL94 standard is used to assess the flame retardant capability. To assess the flame retardant capability of a resin, such as a plastic, it is first determined whether the material is self-extinguishing. The burning tests according to the UL94 standard generally include a horizontal burning test for resin materials that are not self-extinguishing, and vertical burning tests for resin materials that are self-extinguishing. Examples of resin materials for the horizontal burning test include HB materials. Examples of resin materials for the vertical burning tests include 5VA, 5VB, V-<NUM>, V-<NUM>, and V-<NUM> materials. As the measures for the grades according to the UL94 standard, a material that passes the horizontal burning test for HB materials needs to exhibit a slow-burning property even though it is not self-extinguishing and have a burning rate of <NUM>/min or less when the test sample has a thickness of <NUM> or more. As for the vertical burning tests, a V-<NUM> material needs to have a burning time of <NUM> seconds or less when a flame is applied to the test sample twice for <NUM> seconds each, and V-<NUM> and V-<NUM> materials need to have a burning time of <NUM> seconds or less when a flame is applied to the test sample twice for <NUM> seconds each. Here, the shorter the burning time, the harder it is to burn. That is, "high flame retardant capability" in this embodiment not only indicates a difference in flame retardant grade but also indicates a shorter burning time in the same burning test.

Other than the UL94 standard, the oxygen index according to the JIS standard may be used. The oxygen index is an index indicating the minimum oxygen concentration in percentage required for an ignited resin material to keep burning. A greater oxygen index indicates higher flame retardant capability. For example, the oxygen index is about <NUM> to <NUM> with an HB material, about <NUM> to <NUM> with a V-<NUM> material, about <NUM> to <NUM> with a V-<NUM> material, and about <NUM> or more with a V-<NUM> material.

As shown in <FIG>, <FIG>, the conductive bearing member <NUM> includes a spring contact <NUM>, which is a power supply member of the image forming apparatus and functions to apply a predetermined bias to the developing roller <NUM>, and a conductive portion <NUM>, which is an electrode member made of a conductive resin. The spring contact <NUM> and the conductive portion <NUM> form an electrically conductive path between the apparatus main body and the developing roller <NUM>.

As shown in <FIG>, the conductive bearing member <NUM> includes the conductive portion <NUM> and a non-conductive portion <NUM> as a second frame (a second member), which are integrally formed. The non-conductive portion <NUM> is made of a material (a second resin material) that has a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of V-<NUM> according to the UL94 standard, that is, has higher flame retardant capability than the developer container <NUM>. As shown in <FIG>, the conductive portion <NUM> includes a contact section 1701a exposed outward to be in contact with the spring contact <NUM>, which is a power supply member of the image forming apparatus, to receive power, and a conductive support section 1701b, which serves as a shaft support section that rotationally supports the developing roller <NUM>.

<FIG> are diagrams for illustrating the details of the conductive bearing member <NUM>. <FIG> are exploded views in which the conductive portion <NUM> and the non-conductive portion <NUM> are displaced in the longitudinal direction. Although <FIG> show the conductive portion <NUM> and the non-conductive portion <NUM> arranged side by side in the longitudinal direction, these portions are not configured to be integrated by fitting to each other in the longitudinal direction. In this embodiment, the conductive portion <NUM> and the non-conductive portion <NUM> are formed by two-color molding, and the conductive portion <NUM> has a section that is shaped to spread on one side of the non-conductive portion <NUM> in the longitudinal direction and a section that is shaped to spread on the other side. For example, the contact section 1701a and the conductive support section 1701b are sections of the conductive portion <NUM> that are formed on opposite sides of the non-conductive portion <NUM> in the longitudinal direction. That is, <FIG> are imaginary views that show the conductive portion <NUM> and the non-conductive portion <NUM> displaced in the longitudinal direction to clarify their configurations (especially the parts of the configurations that are invisible from the outside when these portions are integrated). <FIG> shows a state in which the conductive portion <NUM> and the non-conductive portion <NUM> are integrated.

As shown in <FIG>, the non-conductive portion <NUM> has an electrode seating surface 1702c, which is opposed to the contact section 1701a in the longitudinal direction and extends in a direction perpendicular to the longitudinal direction.

The contact section 1701a of the conductive portion <NUM> is closer to the non-conductive portion <NUM> than to the developer container <NUM> and in contact with the non-conductive portion <NUM>. For example, if an incident such as anomalies in the high voltage power source of the apparatus main body A causes an electric discharge between the spring contact <NUM>, which serves as the power supply portion, and the contact section 1701a, this may create an electric ignition source. In this respect, the present configuration has the non-conductive portion <NUM> with high flame retardant capability in contact with the contact section 1701a. If any ignition occurring in the contact section 1701a is about to spread the fire to the non-conductive portion <NUM>, the non-conductive portion <NUM> generates nonflammable gas from the inside of its material and carbonizes the resin surface to stop the spreading of the fire to the inside of the resin, thereby facilitating self-extinguishing. As a result, even when the contact section 1701a of the conductive portion <NUM> is located near the developer container <NUM>, the spreading of fire to the developer container <NUM> can be prevented since the contact section 1701a is closer to the non-conductive portion <NUM> than to the developer container <NUM>. The term "vicinity" used herein refers to a range that is affected by ignition originating from an electric ignition source caused by electric discharge occurring between the power supply portion and the contact section due to anomalies or the like.

That is, in the cartridge B of this embodiment, the developer container <NUM> is made of an HB material that is a low-density resin material to reduce the overall weight of the product, while a highly flame-retardant V-<NUM> material is used in the vicinity of the connection section, which serves as an electrically conductive path, between the apparatus main body A and the cartridge B. This provides the cartridge B that achieves both the safety and weight reduction of the entire product.

Additionally, the bearing member <NUM>, which serves as a third frame (a third member), holds the conductive bearing member <NUM> and is fastened to the developer container <NUM>. This bearing member <NUM> is made of a material that has a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of V-<NUM> according to the UL94 standard. Furthermore, as shown in <FIG>, the bearing member <NUM> is adjacent to the conductive portion <NUM> and has a protruding section 27a that protrudes beyond the electrode seating surface 1702c (see <FIG>) of the non-conductive portion <NUM> in the longitudinal direction W. That is, the bearing member <NUM> has the protruding section 27a formed so as to shield the electrode seating surface 1702c of the non-conductive portion <NUM> from the outside. For example, anomalies in the high voltage power source of the apparatus main body A or other factors may cause an electric discharge between the spring contact <NUM>, which serves as a power supply portion, and the contact section 1701a of the conductive portion <NUM>, resulting in electric ignition. At this time, even if ignition occurs in the area from the contact section 1701a of the conductive portion <NUM> to the electrode seating surface 1702c of the non-conductive portion <NUM> in the longitudinal direction W, the protruding section 27a contains the nonflammable gas generated from the non-conductive portion <NUM> and the bearing member <NUM>. This further facilitates the self-extinguishing of the non-conductive portion <NUM>, so that the spreading of fire can be stopped at the electrode seating surface 1702c. Accordingly, the safety can be further improved.

In terms of the containment of the nonflammable gas and the suppression of fire spreading, the protruding section 27a is preferably configured to protrude so as to completely surround the periphery (outer circumference) of the electrode seating surface 1702c. However, the protruding section 27a may have any of various configurations as long as it provides a certain effect. Since fire tends to spread upward in the vertical direction, the effect of preventing fire spreading can be achieved by arranging the protruding section 27a so as to obstruct the space between the electrode seating surface 1702c and the developer container <NUM>, which is the first frame, at least above the electrode seating surface 1702c in the vertical direction. That is, the protruding section of the present invention can have the effect of suppressing the spreading of fire when ignition occurs, as long as the protruding section at least has a section extending above the contact section in the vertical direction. It should be apparent that the same applies to the configurations of the other protruding sections described below.

<FIG> are perspective views for illustrating the configuration of the conductive bearing member <NUM> in detail. <FIG> shows the conductive bearing member <NUM> in which the conductive portion <NUM> and the non-conductive portion <NUM> are integrally molded. <FIG> are imaginary views showing the conductive portion <NUM> and the non-conductive portion <NUM> of the conductive bearing member <NUM> displaced in the longitudinal direction for illustration purpose.

As shown in <FIG>, the conductive portion <NUM> and the non-conductive portion <NUM> of the conductive bearing member <NUM> are made of different resin materials and formed integrally. The conductive portion <NUM> has a conductive support section 1701b that supports the inner circumference portion of the developing roller <NUM>, which is a rotating member. Referring to <FIG>, which shows a cross section of <FIG>, the non-conductive portion <NUM> has an inner circumference support section 1702a and an outer circumference support section 1702b for supporting the conductive portion <NUM>. The inner circumference support section 1702a and the outer circumference support section 1702b support the cylindrical conductive support section 1701b of the conductive portion <NUM> so as to sandwich it from both the inner circumference side and the outer circumference side. This limits the tilting of the conductive support section 1701b relative to the non-conductive portion <NUM> even when a gap is created between the conductive portion <NUM> and the non-conductive portion <NUM> due to the difference in heat expansion rate of the materials. The developing roller <NUM> can therefore rotate stably.

<FIG> is an enlarged view for illustrating the configuration of the conductive portion <NUM> in detail. The conductive portion <NUM> includes a connection section 1701e for connecting the contact section 1701a and the conductive support section 1701b. As described above, the conductive portion <NUM> and the non-conductive portion <NUM> are formed by two-color molding, and the conductive portion <NUM> has a section that is formed by the resin that has spread on one side of the non-conductive portion <NUM> in the longitudinal direction and a section that is formed by the resin that has spread on the other side in the molding. The connection section 1701e is the section that connects the section that is shaped to spread on one side of the non-conductive portion <NUM> in the longitudinal direction, which is the contact section 1701a, and the section that is shaped to spread on the other side, which is the conductive support section 1701b. In the two-color molding of the conductive portion <NUM>, resin is injected through a gate section 1701c, which serves as the injection port, into the cavity in the order of the contact section 1701a, the connection section 1701e, and the conductive support section 1701b. In this configuration, as viewed in a direction perpendicular to a plane including the contact section 1701a, the conductive portion <NUM> is shaped such that the gate section 1701c and the connection section 1701e overlap (overlap and are included in) the contact section 1701a. Furthermore, as viewed in the same direction, the contact section 1701a and the conductive support section 1701b partially overlap each other. That is, the resin injection path from the gate section 1701c to the conductive support section 1701b is shorter than that in a configuration in which the injection path bypasses and extends outside the non-conductive portion <NUM>, for example. This reduces the amount of resin material used to form the conductive portion <NUM>. Consequently, in case of any ignition of the contact section 1701a, the spreading of fire along the conductive resin can be reduced, increasing the safety of the contact configuration.

In this embodiment, polystyrene (PS) is used for the developer container <NUM> as the first frame. A mixed resin of polycarbonate and acrylonitrile butadiene styrene (PC-ABS) is used for the non-conductive portion <NUM> as the second frame and the bearing member <NUM> as the third frame. A conductive polyacetal (POM) is used for the conductive portion <NUM> as the resin electrode member. However, these materials are not limited to those of the present embodiment.

Referring to <FIG>, <FIG>, the charging contact configuration, which is a feature of the present embodiment, is now described in detail. <FIG> is an exploded perspective view showing the key components of the charging contact configuration extracted. <FIG> is a side view for illustrating the charging contact configuration. <FIG> is an enlarged cross-sectional view of the charging contact taken along line G-G in <FIG>.

As shown in <FIG>, the cleaning unit <NUM> has a cleaning frame <NUM>, which serves as a first frame. As shown in <FIG>, the charging roller <NUM>, which serves as a process unit, is provided inside the cleaning frame <NUM>. As shown in <FIG>, an electrode plate <NUM>, which electrically connects the charging roller <NUM> to the apparatus main body, is attached to the side surface of the cleaning frame <NUM> on the non-drive side. The cleaning frame <NUM> is made of a material having a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of HB according to the UL94 standard. The cleaning frame <NUM> supports the charging roller <NUM> as a rotational rotating member through the charging roller bearing <NUM>. The charging roller <NUM> rotates while receiving a predetermined bias to uniformly charge the surface of the photosensitive drum <NUM>. To apply the predetermined bias to the charging roller <NUM>, the cleaning unit <NUM> includes an electrode plate <NUM>, which is an electrode member made of metal, as an electrically conductive path from the image forming apparatus A to the charging roller <NUM>. The electrode plate <NUM> has a contact surface 82a exposed outward to receive power from a spring contact <NUM>, which is a power supply member provided in the image forming apparatus.

The cleaning unit <NUM> also includes a contact cover <NUM>, which serves as a second frame and is made of a material that has a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of V-<NUM> according to the UL94 standard, that is, has higher flame retardant capability than the cleaning frame <NUM>. As shown in <FIG>, a part of the contact cover <NUM>, which is a contact protection member, has a protruding section 83a protruding in the longitudinal direction W beyond the contact surface 82a. For example, when a bias is applied in a state in which combustible foreign matter, such as dust, is caught between the spring contact <NUM> and the contact surface 82a of the electrode plate <NUM>, the foreign matter may ignite due to tracking. In such a case, the protruding section 83a, which is made of a highly flame-retardant material, functions as a fire-spreading prevention wall, preventing the fire from spreading to the inside of the cartridge B including the cleaning frame <NUM>.

That is, in the cartridge B of the present embodiment, the cleaning frame <NUM> is made of an HB material that is a low-density resin material to reduce the overall weight of the product. On the other hand, the protruding section 83a, which is made of a highly flame-retardant V-<NUM> material, is arranged between the cleaning frame <NUM> and the connection section, which is an electrically conductive path, between the apparatus main body A and the cartridge B. This provides the cartridge B that achieves both the safety and weight reduction of the entire product.

In this embodiment, the cleaning frame <NUM> as the first frame uses PS, the contact cover <NUM> as the second frame uses PC-ABS, and the electrode plate <NUM> as the metal electrode member uses stainless steel. However, these materials are not limited to those of the present embodiment.

In the present embodiment, the process cartridge B is formed by integrating the developing unit <NUM> and the cleaning unit <NUM>. However, the configuration of the cartridge according to the present invention is not limited to the configuration of the present embodiment. For example, in an apparatus configuration in which the developing unit <NUM> and the cleaning unit <NUM> can be independently attached to and detached from the apparatus main body, each unit may correspond to the cartridge according to the present invention. The same applies to the embodiments described below.

Another embodiment of the above-mentioned charging contact configuration is now described.

Referring to <FIG>, <FIG>, <FIG>, another embodiment of the charging contact configuration is now described in detail. <FIG> is a perspective view showing a cleaning frame body portion independently extracted as a key component of the charging contact configuration. <FIG> is a perspective view showing key components of the charging contact configuration extracted in a state in which a contact cover portion is formed in the cleaning frame body portion by two-color molding. <FIG> is an exploded perspective view showing the key components of the charging contact configuration extracted. <FIG> is a side view for illustrating the charging contact configuration. <FIG> is an enlarged cross-sectional view of the charging contact taken along line H-H in <FIG>. The present embodiment is a modification in which the contact cover <NUM> as the second frame described above with reference to <FIG> is integrally formed with the cleaning frame <NUM>. The other configurations are the same and thus not described.

As shown in <FIG>, a cleaning unit <NUM> includes a cleaning frame <NUM>, which serves as a first frame.

As shown in <FIG>, the cleaning frame <NUM> includes a cleaning frame body portion 3071a and a cleaning frame contact cover portion 3071b. The cleaning frame contact cover portion 3071b is integrally formed with the cleaning frame body portion 3071a by two-color molding. The cleaning frame body portion 3071a is made of a material having a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of HB according to the UL94 standard. The cleaning frame contact cover portion 3071b is made of a material that has a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of V-<NUM> according to the UL94 standard, that is, has higher flame retardant capability than the cleaning frame <NUM>.

As shown in <FIG>, a part of the cleaning frame contact cover portion 3071b, which is a contact protection member, has a protruding section 3071c protruding in the longitudinal direction WW beyond a contact surface 3082a.

For example, when a bias is applied in a state in which combustible foreign matter, such as dust, is caught between a spring contact <NUM> and the contact surface 3082a of an electrode plate <NUM>, the foreign matter may ignite due to tracking. In such a case, the protruding section 3071c, which is made of a highly flame-retardant material, functions as a fire-spreading prevention wall, preventing the fire from spreading to the inside of the cartridge including the cleaning frame <NUM>.

That is, in the cartridge of the present embodiment, the cleaning frame <NUM> is also made of an HB material that is a low-density resin material, thereby reducing the overall weight of the product as described above. On the other hand, the protruding section 3071c, which is made of a highly flame-retardant V-<NUM> material, is arranged between the cleaning frame <NUM> and the connection section, which is an electrically conductive path, between the apparatus main body and the cartridge. This provides the cartridge that achieves both the safety and weight reduction of the entire product.

In this embodiment, the cleaning frame body portion 3071a of the cleaning frame <NUM> as the first frame uses PS, the cleaning frame contact cover portion 3071b, which has a similar function as the second frame described above, uses PC-ABS, and the electrode plate <NUM> as the metal electrode member uses stainless steel. However, these materials are not limited to those of the present embodiment.

Referring to <FIG>, the overall configuration of an electrophotographic image forming apparatus <NUM> (hereinafter, image forming apparatus <NUM>) of a second embodiment of the present invention is now described. <FIG> is a schematic view of the image forming apparatus <NUM> according to the present embodiment. In this embodiment, process cartridges <NUM> and toner cartridges <NUM> are attachable to and detachable from the apparatus main body of the image forming apparatus <NUM>. In this embodiment, first to fourth image forming portions substantially have the same configuration and operation except that they form images of different colors. As such, these portions will be described collectively without using the suffixes Y to K where it is not necessary to distinguish them.

The first to fourth process cartridges <NUM> are arranged side by side in the horizontal direction. Each process cartridge <NUM> includes a cleaning unit <NUM> and a developing unit <NUM>. The cleaning unit <NUM> includes a photosensitive drum <NUM> as an image bearing member, a charging roller <NUM> as a charging unit for uniformly charging the surface of the photosensitive drum <NUM>, and a cleaning blade <NUM> as a cleaning unit. The developing unit <NUM> accommodates a developing roller <NUM> and developer T (hereinafter, toner), and includes a developing unit for developing electrostatic latent images on the photosensitive drum <NUM>. The cleaning unit <NUM> and the developing unit <NUM> are supported so as to be pivotal relative to each other. A first process cartridge 1Y contains yellow (Y) toner in the developing unit <NUM>. Similarly, a second process cartridge <NUM> contains magenta (M) toner, a third process cartridge 2500C contains cyan (C) toner, and a fourth process cartridge <NUM> contains black (K) toner.

The process cartridges <NUM> can be attached to and detached from the image forming apparatus <NUM> through an attachment unit such as an attachment guide (not shown) and a positioning member (not shown) provided in the image forming apparatus <NUM>. A scanner unit <NUM>, which serves as an exposure unit for forming an electrostatic latent image, is arranged under the process cartridge <NUM>. Furthermore, the image forming apparatus includes a waste toner transport unit <NUM> arranged rearward of the process cartridges <NUM> (downstream side in the attachment/detachment direction of the process cartridges <NUM>).

The first to fourth toner cartridges <NUM> are arranged side by side in the horizontal direction under the process cartridges <NUM> in an order corresponding to the colors of the toner contained in the process cartridges <NUM>. That is, the first toner cartridge 2550Y contains yellow (Y) toner. Similarly, the second toner cartridge <NUM> contains magenta (M) toner, the third toner cartridge 2550C contains cyan (C) toner, and the fourth toner cartridge <NUM> contains black (K) toner. Each toner cartridge <NUM> supplies toner to the process cartridge <NUM> containing toner of the same color.

The replenishing operation of the toner cartridges <NUM> is performed when the toner level detection unit (not shown) installed in the apparatus main body of the image forming apparatus <NUM> detects a shortage of toner remaining in the process cartridges <NUM>. The toner cartridges <NUM> can be attached to and detached from the image for apparatus <NUM> through an attachment unit such as an attachment guide (not shown) and a positioning member (not shown) provided in the image forming apparatus <NUM>. The process cartridges <NUM> will be described in detail below.

First to fourth toner transport devices <NUM> are arranged under the toner cartridges <NUM> corresponding to the respective toner cartridges <NUM>. Each toner transport device <NUM> transports the toner received from the toner cartridge <NUM> upward to supply the toner to the corresponding developing unit <NUM>. An intermediate transfer unit <NUM>, which serves as an intermediate transfer member, is provided above the process cartridges <NUM>. The intermediate transfer unit <NUM> is arranged substantially horizontally with its primary transfer portion S1 on the lower side. An intermediate transfer belt <NUM>, which is a rotational endless belt, faces the photosensitive drums <NUM> and is stretched over a plurality of tension rollers. On the inner surface of the intermediate transfer belt <NUM>, primary transfer rollers <NUM> as primary transfer members are located at respective positions where they form primary transfer portions S1 with the respective photosensitive drums <NUM> through the intermediate transfer belt <NUM>. A secondary transfer roller <NUM> as a secondary transfer member is in contact with the intermediate transfer belt <NUM> and forms a secondary transfer portion S2 with the roller on the opposite side through the intermediate transfer belt <NUM>. Furthermore, an intermediate transfer belt cleaning unit <NUM> is arranged on the opposite side from the secondary transfer portion S2 in the left-right direction (direction in which the secondary transfer portion S2 and the intermediate transfer belt are stretched).

A fixing unit <NUM> is located further above the intermediate transfer unit <NUM>. The fixing unit <NUM> includes a heating unit <NUM> and a pressing roller <NUM>, which presses against the heating unit <NUM>. A discharge tray <NUM> is arranged on the upper surface of the apparatus main body, and a waste toner collection container <NUM> is arranged between the discharge tray <NUM> and the intermediate transfer unit. In addition, a paper feed tray <NUM> is located at the bottom of the apparatus main body to store recording materials <NUM>.

Referring to <FIG> and <FIG>, an image forming operation of the image forming apparatus <NUM> is now described. <FIG> is a schematic cross-sectional view of a process cartridge according to the present embodiment.

During image formation, a photosensitive drum <NUM> is driven to rotate at a predetermined speed in the direction of arrow a in <FIG>. The intermediate transfer belt <NUM> is driven to rotate in the direction of arrow b in <FIG> (in the forward direction of the rotation of the photosensitive drum <NUM>).

First, the charging roller <NUM> uniformly charges the surface of the photosensitive drum <NUM>. Then, a laser beam is emitted from the scanner unit <NUM> to the surface of the photosensitive drum <NUM> for scanning exposure, thereby forming an electrostatic latent image on the photosensitive drum <NUM> according to image information. The electrostatic latent image formed on the photosensitive drum <NUM> is developed as a toner image (developer image) by the developing unit <NUM>. At this time, the developing unit <NUM> is pressurized by the development pressure unit (not shown) provided in the main body of the image forming apparatus <NUM>. The toner image formed on the photosensitive drum <NUM> is transferred, as primary transfer, onto the intermediate transfer belt <NUM> by the primary transfer roller <NUM>.

For example, to form a full-color image, the above process is sequentially performed in the image forming portions S1Y to S1K, which are the first to fourth primary transfer units, so that toner images of different colors are sequentially superimposed on the intermediate transfer belt <NUM>.

Meanwhile, the recording material <NUM> stored in the paper feed tray <NUM> is fed at predetermined control timing and transported to the secondary transfer portion S2 in synchronization with the movement of the intermediate transfer belt <NUM>. Then, the four-color toner images on the intermediate transfer belt <NUM> are collectively transferred, as secondary transfer, onto the recording material <NUM> by the secondary transfer roller <NUM>, which is in contact with the intermediate transfer belt <NUM> through the recording material <NUM>.

Then, the recording material <NUM> to which the toner image is transferred is transported to the fixing unit <NUM>. The fixing unit <NUM> applies heat and pressure to the recording material <NUM> thereby fixing the toner image on the recording material <NUM>. After the fixation, the recording material <NUM> is transported to the discharge tray <NUM> to complete the image forming operation. Also, the cleaning blades <NUM> remove the primary-transfer residual toner (waste toner) remaining on the photosensitive drums <NUM> after the primary transfer step. The intermediate transfer belt cleaning unit <NUM> removes the secondary-transfer residual toner (waste toner) remaining on the intermediate transfer belt <NUM> after the secondary transfer step. The waste toner removed by the cleaning blades <NUM> and the intermediate transfer belt cleaning unit <NUM> is transported by a waste toner transport unit <NUM> provided in the apparatus main body and stored in the waste toner collection container <NUM>. The image forming apparatus <NUM> can also form a monochromatic or multicolor image by using only one or some (but not all) desired image forming portions.

Referring to <FIG> and <FIG>, the overall configuration of the process cartridges <NUM> to be attached to the image forming apparatus <NUM> according to the present embodiment is now described. <FIG> is a schematic cross-sectional view of a process cartridge <NUM> according to the present embodiment. <FIG> is a perspective view of the process cartridge <NUM> as viewed from the bottom surface side. <FIG> is a perspective view of the process cartridge <NUM> as viewed from the top surface side.

The process cartridge <NUM> includes a cleaning unit <NUM> and a developing unit <NUM>. The cleaning unit <NUM> and the developing unit <NUM> are connected so as to be pivotal about a rotation support pin <NUM>.

The cleaning unit <NUM> includes a cleaning frame <NUM>, which supports various members in the cleaning unit <NUM>. In addition to the photosensitive drum <NUM>, the charging roller <NUM>, and the cleaning blade <NUM>, the cleaning unit <NUM> includes a waste toner screw <NUM> extending parallel to the rotation axis of the photosensitive drum <NUM>. The cleaning frame <NUM> includes cleaning bearings <NUM>, which rotationally support the photosensitive drum <NUM> at opposite longitudinal ends of the cleaning unit <NUM>. The cleaning bearings <NUM> include cleaning gear trains for transmitting drive from the photosensitive drum <NUM> to the waste toner screw <NUM>.

The charging roller <NUM> is urged toward the photosensitive drum <NUM> in the direction of arrow c by charging roller pressure springs <NUM> arranged at both ends. The charging roller <NUM> is provided so as to be driven by the photosensitive drum <NUM>. When the photosensitive drum <NUM> is driven to rotate in the direction of arrow a during image formation, the charging roller <NUM> is rotated in the direction of arrow d (forward direction of the rotation of the photosensitive drum <NUM>).

The cleaning blade <NUM> includes an elastic member 2505a for removing transfer residual toner (waste toner) remaining on the surface of the photosensitive drum <NUM> after primary transfer, and a support member 2505b for supporting the elastic member 2505a. The waste toner removed from the surface of the photosensitive drum <NUM> by the cleaning blade <NUM> is stored in a waste toner storage chamber <NUM> defined by the cleaning blade <NUM> and the cleaning frame <NUM>. The waste toner screw <NUM> in the waste toner storage chamber <NUM> transports the waste toner stored in the waste toner storage chamber <NUM> rearward of the image forming apparatus <NUM> (downstream side in the attachment/detachment direction of the process cartridge <NUM>). The transported waste toner is discharged through a waste toner discharge portion <NUM> and delivered to the waste toner transport unit <NUM> of the image forming apparatus <NUM>.

The developing unit <NUM> has a development frame <NUM>, which supports various members of the developing unit <NUM>. The development frame <NUM> is partitioned into a developing chamber 2514a, which accommodates a developing roller <NUM> and a supply roller <NUM>, and a toner storage chamber 2514b, which stores toner and accommodates an agitation member <NUM>.

The developing chamber 2514a accommodates the developing roller <NUM>, the supply roller <NUM>, and a development blade <NUM>. The developing roller <NUM> carries toner as a developer carrying member, rotates in the direction of arrow e during image formation, and transports the toner to the photosensitive drum <NUM> by coming into contact with the photosensitive drum <NUM>. The developing roller <NUM> is rotationally supported by the development frame <NUM> through development bearing units <NUM> at its opposite ends in the longitudinal direction (rotation axis direction). The supply roller <NUM>, which serves as a developer supply member, is rotationally supported by the development frame <NUM> through the development bearing units <NUM> so as to be rotatable in contact with the developing roller <NUM>. The supply roller <NUM> rotates in the direction of arrow f during image formation. Furthermore, the development blade <NUM>, which serves as a layer thickness controlling member that controls the thickness of the toner layer formed on the developing roller <NUM>, is arranged in contact with the surface of the developing roller <NUM>.

The toner storage chamber 2514b accommodates the agitation member <NUM>, which agitates the stored toner T and transports the toner to the supply roller <NUM> through a developing chamber communication port 2514c. The agitation member <NUM> includes a rotation shaft 2516a, which is parallel to the rotation axis of the developing roller <NUM>, and an agitation sheet 2516b, which is flexible and serves as a transport member. One edge of the agitation sheet 2516b is fixed to the rotation shaft 2516a, and the other edge of the agitation sheet 2516b is a free edge. The agitation sheet 2516b rotates in the direction of arrow g when the rotation shaft 2516a rotates, so that the toner is agitated by the agitation sheet 2516b.

The developing unit <NUM> has the developing chamber communication port 2514c, which provides communication between the developing chamber 2514a and the toner storage chamber 2514b. In the present embodiment, when the developing unit <NUM> is at normal orientation (orientation during use), the developing chamber 2514a is located above the toner storage chamber 2514b. The toner in the toner storage chamber 2514b that is lifted by the agitation member <NUM> is supplied to the developing chamber 2514a through the developing chamber communication port 2514c.

The developing unit <NUM> also has a receiving port <NUM> at one end on the downstream side in the attachment/detachment direction. A receiving port seal member <NUM> and a toner receiving port shutter <NUM>, which is movable in the front-rear direction, are arranged above the toner receiving port <NUM>. When the process cartridge <NUM> is not attached to the image forming apparatus <NUM>, the toner receiving port shutter <NUM> closes the toner receiving port <NUM>. The toner receiving port shutter <NUM> is configured to be urged and opened by the image forming apparatus <NUM> in time with the attachment/detachment operation of the process cartridge <NUM>. A receiving transport passage <NUM> is provided in communication with the toner receiving port <NUM>, and a receiving transport screw <NUM> is arranged in the receiving transport passage <NUM>. A storage chamber communication port <NUM> for supplying toner to the toner storage chamber 2514b is provided near the longitudinal center of the development bearing unit <NUM>, and provides communication between the receiving transport passage <NUM> and the toner storage chamber 2514b. The receiving transport screw <NUM> extends parallel to the rotation axes of the developing roller <NUM> and the supply roller <NUM> and transports the toner received from the toner receiving port <NUM> to the toner storage chamber 2514b through the storage chamber communication port <NUM>.

Referring to <FIG>, <FIG>, <FIG>, the development contact configuration, which is a feature of the present embodiment, is now described in detail. <FIG> is an exploded perspective view of the developing unit <NUM> showing the key components of the development contact configuration extracted. <FIG> is a perspective view of the developing unit <NUM>, <FIG> is a side view for illustrating the development contact configuration, and <FIG> is an enlarged cross-sectional view of the development contact taken along line B-B in <FIG>.

As shown in <FIG>, the developing unit <NUM> includes a development frame <NUM> as a first frame and a developing roller <NUM> as a process unit. The development frame <NUM> is made of a material having a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of HB according to the UL94 standard. It is known that adding an additive to a resin material, which generally has the property of igniting in contact with fire, can render the resin flame retardant. When an additive is added to one type of resin material, a higher flame-retardant effect results in a greater specific gravity of the resin. This may increase the weight of the necessary resin material in the entire product, causing a greater load on the environment. In the present embodiment, the development frame <NUM> is made of a material that is free of such an additive and has a low density. The developing roller <NUM> has the function of carrying developer by receiving a predetermined bias. The developing roller <NUM>, which serves as a rotating member, is rotationally supported by the development frame <NUM> through the development bearing units <NUM>.

As shown in <FIG>, <FIG>, the development bearing unit <NUM> includes a conductive portion <NUM>, which is an electrode member made of a conductive resin, to apply the predetermined bias to the developing roller <NUM>. The conductive portion <NUM> forms an electrically conductive path from a development spring contact <NUM>, which is a power supply member of the image forming apparatus, to the developing roller <NUM>.

As shown in <FIG>, the development bearing unit <NUM> is formed by integrally forming the conductive portion <NUM> and a non-conductive portion <NUM>, which serves as the second frame, by two-color molding or the like. The non-conductive portion <NUM> is made of a material that has a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of V-<NUM> according to the UL94 standard, that is, has higher flame retardant capability than the development frame <NUM>. As shown in <FIG>, the conductive portion <NUM> includes a contact section 2530a exposed outward to be in contact with the development spring contact <NUM> (<FIG>), which is a power supply member of the image forming apparatus, to receive power, and a conductive support section 2530b, which rotationally supports the developing roller <NUM>.

As shown in <FIG>, in this configuration, the non-conductive portion <NUM> as the second frame forms a seating surface for forming the conductive portion <NUM>. When the seating surface formed by the non-conductive portion <NUM> is 2531a, the non-conductive portion <NUM> has a protruding section 2531b that is adjacent to the conductive portion <NUM> and protrudes beyond the seating surface 2531a in a direction perpendicular to the seating surface 2531a. The conductive portion <NUM> is formed by two-color molding so as to be surrounded by the non-conductive portion <NUM> except for the surface that is to be in contact with the development spring contact <NUM>.

For example, anomalies in the high voltage power source may cause an electric discharge at the contact surface 2530a between the development spring contact <NUM>, which is a power supply portion, of the image forming apparatus main body and the conductive portion <NUM>. This may create an electric ignition source. In this respect, the present configuration has the non-conductive portion <NUM>, which has a high flame retardancy and surrounds the conductive portion <NUM>. With this configuration, if any ignition at the contact surface 2530a is about to spread the fire to the non-conductive portion <NUM>, the nonflammable gas generated from the inside of the material of the non-conductive portion <NUM> acts to extinguish the flame, thereby preventing the spreading of fire to the development frame <NUM>.

That is, in the present embodiment, the development frame <NUM> is also made of an HB material that is a low-density resin material to reduce the overall weight of the product, while a highly flame-retardant V-<NUM> material is used in the vicinity of the connection section, which serves as an electrically conductive path, between the apparatus main body and the process cartridge. This provides the process cartridge that achieves both the safety and weight reduction of the entire product.

Referring to <FIG>, <FIG>, <FIG>, the charging contact configuration, which is a feature of the present embodiment, is now described in detail. <FIG> is an exploded perspective view showing the key components of the charging contact configuration extracted. <FIG> is a side view for illustrating the charging contact configuration. <FIG> is an enlarged cross-sectional view of the charging contact taken along line E-E in <FIG>.

As shown in <FIG>, the cleaning unit <NUM> includes the cleaning frame <NUM> as the first frame and the charging roller <NUM> as a process unit (charging member). The cleaning frame <NUM> is made of a material having a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of HB according to the UL94 standard. The cleaning frame <NUM> supports the charging roller <NUM> as a rotational rotating member through the charging roller bearing <NUM>. The charging roller bearing <NUM> includes a charging roller bearing member <NUM> made of a conductive resin and a charging roller spring member <NUM> formed by a metal compression spring. The charging roller <NUM> rotates while receiving a predetermined bias to uniformly charge the surface of the photosensitive drum <NUM>. To apply the predetermined bias to the charging roller <NUM>, the cleaning unit <NUM> includes an electrode plate <NUM> shown in <FIG>, which is an electrode member made of metal, as an electrically conductive path from the image forming apparatus <NUM> to the charging roller <NUM>. As shown in <FIG>, the electrode plate <NUM> has a contact surface 2528a exposed outward to receive power from a spring contact <NUM>, which is a power supply member provided in the image forming apparatus.

The cleaning unit <NUM> also includes a contact cover <NUM> as a second frame. The contact cover <NUM> is made of a material that has a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of V-<NUM> according to the UL94 standard, that is, has higher flame retardant capability than the cleaning frame <NUM>. As shown in <FIG>, a part of the contact cover <NUM> has a protruding section 2529a protruding in the longitudinal direction W beyond the contact surface 2528a. For example, when combustible foreign matter, such as dust, is held between the spring contact <NUM> and the contact surface 2528a of the electrode plate <NUM>, the foreign matter may cause ignition due to tracking. In such a case, the protruding section 2529a, which is made of a highly flame-retardant material, functions as a fire-spreading prevention wall. This prevents the fire from spreading to the inside of the process cartridge <NUM> including the cleaning frame <NUM>.

That is, the cleaning frame <NUM> is made of an HB material that is a low-density resin material to reduce the overall weight of the product, while the protruding section 2529a made of a highly flame-retardant V-<NUM> material is located at the electric conductive path between the apparatus main body <NUM> and the cleaning frame <NUM>. This provides the cartridge that achieves both the safety and weight reduction of the entire product.

A third embodiment according to the present invention is now described referring to drawings. The third embodiment is an example of an image forming apparatus to which four process cartridges can be attached and detached. The number of process cartridges attached to the image forming apparatus is not limited to this, and may be set as appropriate. Also, in the following embodiment, a laser beam printer is described as an example of an image forming apparatus.

<FIG> is a schematic cross-sectional view of an image forming apparatus M. <FIG> is a cross-sectional view of a process cartridge <NUM>. The image forming apparatus M is a full-color laser printer of four colors using an electrophotographic process, and forms color images on recording media (recording material) S. The image forming apparatus M uses the process cartridge system. The process cartridges <NUM> are attached in a detachable manner to the image forming apparatus main body <NUM> to form color images on the recording medium S.

The side of the image forming apparatus M including a front door <NUM> is referred to as a front surface, and the side opposite to the front surface is referred to as a back (rear) surface. The right side of the image forming apparatus M as viewed from the front is referred to as a drive side, and the left side is referred to as a non-drive side. The upper side of the image forming apparatus M as viewed from the front is referred to as an upper surface, and the lower side is referred to as a lower surface. <FIG> is a cross-sectional view of the image forming apparatus M as viewed from the non-drive side. The front side in a direction perpendicular to the drawing plane is the non-drive side of the image forming apparatus M, the right side in the drawing is the front of the image forming apparatus M, and the rear side in a direction perpendicular to the drawing plane is the drive side of the image forming apparatus M.

Also, the drive side of the process cartridge <NUM> is the side on which a drum coupling member (photosensitive coupling member), which will be described below, is arranged as viewed in the axial direction of the photosensitive drum. Furthermore, the drive side of the process cartridge <NUM> is the side on which a development coupling member, which will be described below, is arranged as viewed in the axial direction of the developing roller (developing member).

First to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>) are arranged in the image forming apparatus main body <NUM> in a substantially horizontal direction. The first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>) have the same electrophotographic process mechanism but differ in the color of developer (hereinafter referred to as toner). The first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>) receive rotational driving force transmitted from a drive output portion (details will be described below) of the image forming apparatus main body <NUM>. Additionally, to each of the first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>), the image forming apparatus main body <NUM> supplies a bias voltage (charging bias, developing bias, etc.) (not shown).

As shown in <FIG>, each of the first to fourth process cartridges <NUM> of the present embodiment includes a photosensitive drum <NUM> and a drum unit <NUM>, which has a charging unit as a process unitacting on the photosensitive drum <NUM>. In some examples, the drum unit <NUM> may include a cleaning unit as well as a charging unit as a process unit. Additionally, each of the first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>) includes a developing unit <NUM>, which has a developing unit for developing an electrostatic latent image on the photosensitive drum <NUM>.

The drum unit <NUM> and the developing unit <NUM> are coupled to each other. A detailed description of the process cartridge <NUM> will be given below. The first process cartridge 2800Y contains yellow (Y) toner in the development frame <NUM> and forms a yellow toner image on the surface of the photosensitive drum <NUM>. The second process cartridge <NUM> contains magenta (M) toner in the development frame <NUM> and forms a magenta toner image on the surface of the photosensitive drum <NUM>. The third process cartridge 2800C contains cyan (C) toner in the development frame <NUM> and forms a cyan toner image on the surface of the photosensitive drum <NUM>. The fourth process cartridge <NUM> contains black (K) toner in the development frame <NUM> and forms a black toner image on the surface of the photosensitive drum <NUM>.

A laser scanner unit <NUM>, which serves as an exposure unit, is provided above the first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>). The laser scanner unit <NUM> outputs a laser beam L according to image information. The laser beam L passes through an exposure window <NUM> of the process cartridge <NUM> and performs scanning exposure on the surface of the photosensitive drum <NUM>. An intermediate transfer unit <NUM> as a transfer member is provided under the first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>). The intermediate transfer unit <NUM> includes a drive roller 2712e, a turn roller 2712c, and a tension roller 2712b, and a flexible transfer belt 2712a, which runs around these rollers. The lower surface of the photosensitive drum <NUM> of each of the first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>) is in contact with the upper surface of the transfer belt 2712a. The contact section serves as a primary transfer portion. Primary transfer rollers 2712d are aligned with the photosensitive drums <NUM> on the inner side of the transfer belt 2712a.

A secondary transfer roller <NUM> is in contact with the drive roller 2712e through the transfer belt 2712a. The contact section between the transfer belt 2712a and the secondary transfer roller <NUM> serves as the secondary transfer portion. A feeding unit <NUM> is provided under the intermediate transfer unit <NUM>. The feeding unit <NUM> includes a paper feed tray 2704a, which houses recording media S, and a paper feed roller 2704b.

A fixing apparatus <NUM> and a paper ejection device <NUM> are provided in the upper left section of the image forming apparatus main body <NUM> as viewed in <FIG>. The upper surface of the image forming apparatus main body <NUM> functions as a paper ejection tray <NUM>. A fixing means of the fixing apparatus <NUM> fixes the toner image on the recording medium S, which is then ejected onto the paper ejection tray <NUM>.

The operation for forming a full-color image is as follows. The photosensitive drum <NUM> of each of the first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>) is driven to rotate at a predetermined speed (in the direction of arrow A in <FIG>).

The transfer belt 2712a is also driven to rotate in the forward direction of rotation of the photosensitive drums <NUM> (direction of arrow C in <FIG>) at a speed corresponding to the speed of the photosensitive drums <NUM>. The laser scanner unit <NUM> is also driven. In synchronization with the driving of the laser scanner unit <NUM>, each charging roller <NUM> uniformly charges the surface of the photosensitive drum <NUM> to a predetermined polarity and potential in each process cartridge. The laser scanner unit <NUM> scans and exposes the surface of each photosensitive drum <NUM> with a laser beam L according to the image signal of each color. As a result, an electrostatic latent image corresponding to the image signal of the corresponding color is formed on the surface of each photosensitive drum <NUM>. The formed electrostatic latent image is developed by the developing roller <NUM>, which is driven to rotate at a predetermined speed.

Through the electrophotographic image forming process operation as described above, a yellow toner image corresponding to the yellow component of the full-color image is formed on the photosensitive drum <NUM> of the first process cartridge 2800Y. Then, this toner image is transferred onto the transfer belt 2712a as primary transfer. Similarly, a magenta toner image corresponding to the magenta component of the full-color image is formed on the photosensitive drum <NUM> of the second process cartridge <NUM>. Then, this toner image is superimposed on the yellow toner image, which has been transferred on the transfer belt 2712a, as primary transfer. Similarly, a cyan toner image corresponding to the cyan component of the full-color image is formed on the photosensitive drum <NUM> of the third process cartridge 2800C. Then, this toner image is superimposed on the yellow-colored and magenta-colored toner images, which have been transferred on the transfer belt 2712a, as primary transfer. Similarly, a black toner image corresponding to the black component of the full-color image is formed on the photosensitive drum <NUM> of the fourth process cartridge <NUM>. Then, this toner image is superimposed on the yellow, magenta, and cyan toner images, which have been transferred on the transfer belt 2712a, as primary transfer.

In this manner, full-color unfixed toner images of four colors of yellow, magenta, cyan, and black are formed on the transfer belt 2712a. Meanwhile, the recording media S are separately fed one by one at predetermined control timing. A recording medium S is introduced into the secondary transfer portion, which is the contact section between the secondary transfer roller <NUM> and the transfer belt 2712a, at predetermined control timing. Thus, as the recording medium S is being transported through the secondary transfer portion, the toner images of the four colors superimposed on the transfer belt 2712a are collectively transferred to the surface of the recording medium S in sequence. Further details of the configuration of the image forming apparatus main body will be described below.

Referring to <FIG>, a cartridge tray (hereinafter referred to as a tray) <NUM> supporting the process cartridges <NUM> is now described in detail. <FIG> is a cross-sectional view of the image forming apparatus M in a state in which the front door <NUM> is open and the tray <NUM> is located inside the image forming apparatus main body <NUM>. <FIG> is a cross-sectional view of the image forming apparatus M in a state in which the front door <NUM> is open, the tray <NUM> is located outside the image forming apparatus main body <NUM>, and the process cartridges <NUM> are housed inside the tray. <FIG> is a cross-sectional view of the image forming apparatus M in a state in which the front door <NUM> is open, the tray <NUM> is located outside the image forming apparatus main body <NUM>, and the process cartridges <NUM> are removed from the tray <NUM>.

As shown in <FIG> and <FIG>, the tray <NUM> is movable relative to the image forming apparatus main body <NUM> in the direction of arrow X1 (pushing direction) and the direction of arrow X2 direction (pulling direction), which are substantially horizontal. That is, the tray <NUM> is provided such that it can be pulled out of and pushed into the image forming apparatus main body <NUM>. When the image forming apparatus main body <NUM> is installed on a horizontal plane, the tray <NUM> is movable substantially in horizontal directions. A state in which the tray <NUM> is located outside the image forming apparatus main body <NUM> (the state shown in <FIG>) is referred to as an outside position. A state in which the front door <NUM> is open, the tray <NUM> is located inside the image forming apparatus main body <NUM>, and the photosensitive drums <NUM> are separated from the transfer belt 2712a (state in <FIG>) is referred to as an inside position.

As shown in <FIG>, the tray <NUM> includes attachment portions 2871a to which the process cartridges <NUM> are removably attached in the outside position. As the tray <NUM> moves, the process cartridges <NUM> placed in the attachment portions 2871a move into the image forming apparatus main body <NUM>. In this movement, a gap is maintained between the transfer belt 2712a and each photosensitive drum <NUM>. In this embodiment, closing the front door <NUM> causes a link mechanism (not shown) to lift the intermediate transfer unit <NUM> in the direction of arrow Z1 to the position for image formation (the position at which the intermediate transfer belt 2712a is in contact with the photosensitive drums <NUM>). Opening the front door <NUM> lowers the intermediate transfer unit <NUM> in the direction of arrow Z2, so that the intermediate transfer belt 2712a is separated from the photosensitive drums <NUM>. Thus, the tray <NUM> can move the process cartridges <NUM> into the image forming apparatus main body <NUM> without the photosensitive drums <NUM> coming into contact with the transfer belt 2712a. As described above, the tray <NUM> allows the plurality of process cartridges <NUM> to be moved together to a position in the image forming apparatus main body <NUM> at which image formation is possible, and also allows them to be pulled out of the image forming apparatus main body <NUM> together.

Referring to <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>, the configuration of a process cartridge <NUM> is now described. <FIG> is an exploded perspective view of a drum unit <NUM>. <FIG> is an exploded perspective view of a developing unit <NUM>. <FIG> is an exploded perspective view of a process cartridge <NUM> as viewed from the drive side, which is one end side in the axial direction of the photosensitive drum <NUM>. <FIG> is an assembly perspective view of a process cartridge <NUM> as viewed from the drive side.

In the present embodiment, the first to fourth process cartridges <NUM> (2800Y, <NUM>, 2800C, and <NUM>) have the same electrophotographic process mechanism but contain toner of different colors and amounts.

Each process cartridge <NUM> includes a photosensitive drum <NUM> (2804Y, <NUM>, 2804C, <NUM>) and a process unit acting on the photosensitive drum <NUM>. The process unit includes a charging roller <NUM> as a charging unit for charging the photosensitive drum <NUM>, a developing roller <NUM> as a developing unit for developing a latent image formed on the photosensitive drum <NUM>, and the like. The process cartridge <NUM> is divided into a drum unit <NUM> (2808Y, <NUM>, 2808C, <NUM>) and a developing unit <NUM> (2809Y, <NUM>, 2809C, <NUM>). In the following description, longitudinal directions (Y1 and Y2 directions) of the drum unit <NUM> and the developing unit <NUM> are directions substantially parallel to the rotation axis ax of the photosensitive drum <NUM>.

As shown in <FIG> and <FIG>, the drum unit <NUM> includes a photosensitive drum <NUM>, a charging roller <NUM>, and a drum frame <NUM>, which is a first frame. The charging roller <NUM> is rotationally supported by a drive-side charging roller bearing 2820a and a non-drive-side charging roller bearing 2820b, and is urged toward the photosensitive drum <NUM> by pressing springs 2821a and 2821b. The photosensitive drum <NUM> is rotationally supported by a drive-side cartridge cover member <NUM> and a non-drive-side cartridge cover member <NUM>, which is a second frame, on opposite ends in the longitudinal direction of the process cartridge <NUM>. The non-drive-side cartridge cover member <NUM> includes an electrode member <NUM>, which receives power from the image forming apparatus main body <NUM>. Details will be described below.

As shown in <FIG> and <FIG>, a coupling member <NUM> for transmitting a driving force to the photosensitive drum <NUM> is provided at one longitudinal end of the photosensitive drum <NUM>. The coupling member <NUM> engages with a main-body drum drive coupling <NUM> (see <FIG>), which serves as a drum drive output portion of the image forming apparatus main body <NUM>. The driving force of a drive motor (not shown) of the image forming apparatus main body <NUM> is transmitted to the photosensitive drum <NUM> through the coupling member <NUM>, and the photosensitive drum <NUM> is rotated in the direction of arrow A (<FIG>). Also, the photosensitive drum <NUM> includes a drum flange <NUM> at the other longitudinal end. The charging roller <NUM> is supported by the drum frame <NUM> so as to be in contact with and rotated by the photosensitive drum <NUM>.

As shown in <FIG> and <FIG>, the developing unit <NUM> includes a developing roller <NUM>, a toner transport roller <NUM>, a development blade <NUM>, a development frame <NUM>, and the like. The development frame <NUM>, which serves as a fourth frame (a fourth member), includes a lower frame 2825a and a lid member 2825b. The lower frame 2825a and the lid member 2825b have a flame retardancy of HB according to the UL94 standard. The lower frame 2825a is joined to the lid member 2825b by ultrasonic welding or the like. The development frame <NUM> includes a toner storage portion <NUM> for storing toner to be supplied to the developing roller <NUM>. The development frame <NUM> rotationally supports the developing roller <NUM> and toner transport roller <NUM> through a drive-side bearing <NUM> and a non-drive-side bearing <NUM>, and holds the development blade <NUM>, which controls the layer thickness of the toner on the circumference of the developing roller <NUM>.

The development blade <NUM> is formed by welding or otherwise joining an elastic member 2830b, which is a metal sheet having a thickness of about <NUM>, to a support member 2830a, which is a metal material having an L-shaped cross section. The development blade <NUM> is fixed to the development frame <NUM> with fixing screws 2830c at two locations on opposite longitudinal ends. The developing roller <NUM> includes a metal core bar 2806c and a rubber portion 2806d.

The developing roller <NUM> is rotationally supported by the drive-side bearing <NUM> and the non-drive-side bearing <NUM>, which are attached to opposite longitudinal ends of the development frame <NUM>. As shown in <FIG>, a development drive input gear <NUM> for transmitting a driving force to the developing unit <NUM> is provided at one longitudinal end of the developing unit <NUM>. The development drive input gear <NUM> includes a development input coupling portion 2832a, which is driven by a main-body development drive coupling <NUM> (see <FIG>) of the image forming apparatus main body <NUM>. The driving force of the drive motor (not shown) of the image forming apparatus main body <NUM> is input to the developing unit <NUM> through the development input coupling portion 2832a, the development drive input gear <NUM>, and the like.

The driving force input to the developing unit <NUM> is transmitted to the developing roller gear <NUM> so that the developing roller <NUM> is rotated in the direction of arrow D in <FIG>. As shown in <FIG>, a development cover member <NUM>, which supports and covers the development drive input gear <NUM>, is provided at one longitudinal end of the developing unit <NUM>. The developing roller <NUM> has a smaller outer diameter than the photosensitive drum <NUM>. In the present embodiment, the outer diameter of the photosensitive drum <NUM> is in the range of Φ18 to Φ22, and the outer diameter of the developing roller <NUM> is in the range of Φ8 to Φ14. These outer diameters allow for efficient placement.

Referring to <FIG>, the coupling of the drum unit <NUM> and the developing unit <NUM> is now described. The drum unit <NUM> and the developing unit <NUM> are coupled through the drive-side cartridge cover member <NUM> and the non-drive-side cartridge cover member <NUM> provided at opposite ends of the process cartridge <NUM> in the longitudinal direction.

The drive-side cartridge cover member <NUM> provided at one longitudinal end of the process cartridge <NUM> has a developing unit support hole 2816a for supporting the developing unit <NUM> in a pivotal (movable) manner. Likewise, the non-drive-side cartridge cover member <NUM> provided at the other longitudinal end of the process cartridge <NUM> has a developing unit support hole 2817a for supporting the developing unit <NUM> in a pivotal manner. The drive-side cartridge cover member <NUM> and the non-drive-side cartridge cover member <NUM> have drum support holes 2816b and 2817b for rotationally supporting the photosensitive drum <NUM>.

At one end, the outer circumference section of the cylindrical section 2828b of the development cover member <NUM> is fitted into the developing unit support hole 2816a of the drive-side cartridge cover member <NUM>. At the other end, the outer circumference section of the cylindrical section (not shown) of the non-drive-side bearing <NUM> is fitted into the developing unit support hole 2817a of the non-drive-side cartridge cover member <NUM>. The longitudinal ends of the photosensitive drum <NUM> are fitted into the drum support hole 2816b of the drive-side cartridge cover member <NUM> and the drum support holes 2817b of the non-drive-side cartridge cover member <NUM>. Then, the drive-side cartridge cover member <NUM> and the non-drive-side cartridge cover member <NUM> are fixed to the drum unit <NUM> with screws or adhesives (not shown), for example. As a result, the developing unit <NUM> is supported by the drive-side cartridge cover member <NUM> and non-drive-side cartridge cover member <NUM> to be rotational relative to the drum unit <NUM> (photosensitive drum <NUM>). The developing roller <NUM> is thus positioned at a location at which the developing roller <NUM> acts on the photosensitive drum <NUM> during image formation.

<FIG> shows a state in which the drum unit <NUM> and the developing unit <NUM> are coupled together through the above steps and integrally formed as the process cartridge <NUM>. The axis connecting the center of the developing unit support hole 2816a of the drive-side cartridge cover member <NUM> and the center of the developing unit support hole 2817a of the non-drive-side cartridge cover member <NUM> is referred to as a pivot axis K. The cylindrical section 2828b of the development cover member <NUM> at one end is coaxial with a development input coupling <NUM>. That is, the developing unit <NUM> is configured to receive a driving force from the image forming apparatus main body <NUM> transmitted along the pivot axis K. Also, the developing unit <NUM> is supported so as to be rotational about the pivot axis K.

Referring to <FIG>, the configuration of the power supply portion of the present embodiment is now described. <FIG> is a perspective view of the area around the section of the drum unit <NUM> that is coupled to the non-drive-side cartridge cover member <NUM>. In <FIG>, only the electrode member <NUM> is shown in an exploded view. <FIG> is a cross-sectional view of the electrode member <NUM>. <FIG> is a cross-sectional view taken along line F-F in <FIG>, showing a state in which the electrode member <NUM> is fixed in <FIG>. <FIG> is a cross-sectional view taken along line J-J in <FIG>, showing a state in which the electrode member <NUM> is fixed in <FIG>.

In the drum frame <NUM>, which is the first frame, the conductive resin <NUM> is integrally formed in the drum frame <NUM> by two-color molding. The conductive resin <NUM> has a surface 2818a that comes into contact with the electrode member <NUM> and a surface 2818b that serves as a seating surface for the pressing spring 2821b. As in the first embodiment, the drum frame as a first frame has a density of about <NUM> to <NUM>/cm<NUM> and a flame retardancy of HB according to the UL94 standard.

The electrode member <NUM> is made of a stainless steel material having a thickness of about <NUM>. The electrode member <NUM> has an embossed contact section 2860c, which comes into contact with the surface 2818a of the conductive resin <NUM>, and a contact surface 2860d, which comes into contact with an electrode spring <NUM> (<FIG> and <FIG>) and receives power. The electrode spring <NUM> supplies power from the image forming apparatus main body <NUM>. The non-drive-side cartridge cover member <NUM>, which serves as a second frame, supports the electrode member <NUM>.

The non-drive-side cartridge cover member <NUM> as the second frame has a density of <NUM> to <NUM>/cm<NUM> and a flame retardancy of V-<NUM> according to the UL94 standard. The electrode member <NUM> has a positioning 2860a, into which a boss 2817c of the non-drive-side cartridge cover member <NUM> is fitted, and a cut and raised section 2860b, which engages with a surface 2817d of the boss 2817c, and is thus fixed (<FIG>).

As shown in <FIG>, the side of the electrode member <NUM> including the contact section 2860c is bent about <NUM>° in the direction of the conductive resin <NUM> relative to a setting surface 2860e that is set on the non-drive-side cartridge cover member <NUM>. This is to prevent the contact section 2860c of the electrode member <NUM> from being separated from the surface 2818a of the conductive resin <NUM> when the electrode member <NUM> is coupled to the non-drive-side cartridge cover member <NUM>. Since the side including the contact section 2860c is bent in the direction into the surface 2818a of the conductive resin <NUM>, when the electrode member <NUM> is coupled to the non-drive-side cartridge cover member <NUM>, the contact section 2860c is in contact with the surface 2818a of the conductive resin <NUM> under a certain pressure. As such, even if the conductive resin <NUM>, the non-drive-side cartridge cover member <NUM>, and the electrode member <NUM> have dimensional variations, the surface 2818a of the conductive resin <NUM> and the contact section 2860c of the electrode member <NUM> are always in contact with each other. This prevents continuity failure, which would otherwise occur due to contact failure between the electrode member <NUM> and the conductive resin <NUM>, and ignition due to tracking.

The voltage supplied from the contact spring <NUM> to the electrode member <NUM> is fed to the charging roller <NUM> via the conductive resin <NUM>, which is formed in the drum frame <NUM> by two-color molding, the pressing spring 2821b, and the non-drive-side charging roller bearing 2820b.

The conductive resin <NUM> is formed by two-color molding in the above configuration, but it may be formed as a separate part and fixed to the drum frame <NUM>, which is the first frame. Also, the electrode member <NUM> is fixed by the cut and raised section 2860b in the above configuration, but the electrode member <NUM> may be fixed using a screw or caulking. Furthermore, the side of the electrode member <NUM> including the contact section 2860c is bent relative to the setting surface 2860e, but the configuration is not limited to this. The thickness of the electrode member <NUM> may be increased to form a deep embossed shape so that the electrode member <NUM> is always in contact with the surface 2818a of the conductive resin <NUM>.

Referring to <FIG>, <FIG>, <FIG>, and <FIG>, the configuration of the power supply portion including the image forming apparatus main body <NUM> is now described. <FIG> is a perspective view of a process cartridge in a state in which a storage element communication unit <NUM> and a contact spring holding member <NUM> are lowered. <FIG> is an enlarged cross-sectional view of the power supply portion taken along line V-V in <FIG>. <FIG> is an enlarged cross-sectional view of the power supply portion taken along line N-N in <FIG>.

The image forming apparatus main body <NUM> includes the contact spring holding member <NUM> and holds the contact spring <NUM> for supplying power to the process cartridge <NUM>. The contact spring holding member <NUM> is fixed to the storage element communication unit <NUM>, which communicates with a storage element (not shown) provided in the process cartridge <NUM>.

The interlocking between the front door <NUM> shown in <FIG> and a link mechanism (not shown) can move the contact spring <NUM> and the electrode member <NUM> into and out of contact with each other. Closing the front door <NUM> lowers the storage element communication unit <NUM> and the contact spring holding member <NUM> in the direction of arrow Z2 (<FIG>). Opening the front door <NUM> lifts the storage element communication unit <NUM> and the contact spring holding member <NUM> in the direction of arrow Z1. That is, closing the front door <NUM> brings the contact spring <NUM> and the electrode member <NUM> into contact with each other, while opening the front door <NUM> separates the contact spring <NUM> and the electrode member <NUM> from each other. The contact spring holding member <NUM> has a flame retardancy of V-<NUM> according to the UL94 standard.

As shown in <FIG>, protruding sections 2817f protrude from the non-drive-side cartridge cover member <NUM> in the direction of arrow Z1 on opposite sides of the electrode member <NUM> (in directions of arrows X1 and X2). The height H1 of the protruding sections 2817f is set to be higher than the contact surface 2860d between the contact spring <NUM> and the electrode member <NUM> in the Z1 direction. In order to reduce a fire-spreading range Q that is created if ignition occurs between the contact spring <NUM> and the electrode member <NUM> due to tracking, the protruding sections 2817f are preferably located in the vicinity of the contact spring <NUM> and the electrode member <NUM>. Fire spreads upward, and the non-drive-side cartridge cover member <NUM>, which is made of a V-<NUM> material and self-extinguishing, does not burn. Consequently, the fire-spreading range Q in the X1 and X2 directions is as indicated by Q in <FIG>.

As shown <FIG>, at the side of the electrode member <NUM> corresponding to the side of arrow Y1 in the longitudinal direction, a protruding section <NUM> is arranged that is integrally connected to the ends in the Y1 direction of the protruding sections 2817f of the non-drive-side cartridge cover member <NUM>. The height H2 of the protruding sections <NUM> is set to be higher in the Z1 direction than the contact surface 2860d between the contact spring <NUM> and the electrode member <NUM>. In order to reduce a fire-spreading range R in the same manner as in the directions X1 and X2, the protruding section <NUM> is preferably located in the vicinity of the contact spring <NUM> and the electrode member <NUM>. As described above with regard to the directions X1 and X2, fire spreads upward, and the non-drive-side cartridge cover member <NUM>, which is made of a V-<NUM> material and self-extinguishing, does not burn. Consequently, the fire-spreading range R in the Y1 and Y2 directions is as indicated by "R" in <FIG>.

In addition, protruding sections 2892a and 2892b also extend in the longitudinal direction from the contact spring holding member <NUM>. The protruding sections 2892a and 2892b are set so as to obstruct the fire-spreading range R.

A situation is now described in which ignition occurs due to tracking between the contact spring <NUM> and the electrode member <NUM>. When ignition occurs between the contact spring <NUM> and the electrode member <NUM>, the fire may spread over the fire-spreading ranges Q and R. However, the fire does not spread because the contact spring holding member <NUM>, which is located above the ignition point (in the Z1 direction), and the non-drive-side cartridge cover member <NUM>, which is located in the longitudinal directions (in the directions of Y1 and Y2) and the front-rear directions (in the directions of X1 and X2) of the ignition point, have a flame retardancy of V-<NUM> and are self-extinguishing. In contrast, when the protruding sections 2817f and <NUM> are not provided, the fire spreads over the fire-spreading ranges Q' and R'. The lack of components that limit the spreading of fire may spread the fire to the development frame <NUM>, which is made of an HB material with low flame retardancy. In contrast, since the present embodiment has the protruding sections 2817f and <NUM> of the non-drive-side cartridge cover member <NUM> and the protruding sections 2892a and 2892b of the contact spring holding member <NUM>, which have a flame retardancy of V-<NUM>, in the fire-spreading range, the fire does not spread to a component with low flame retardancy.

As described above, the protruding sections 2817f and <NUM> of the non-drive-side cartridge cover member <NUM> are provided around the electrode member <NUM>, and the contact spring holding member <NUM> having the protruding sections 2892a and 2892b is arranged above the fire-spreading range. Additionally, the non-drive-side cartridge cover member <NUM> and the contact spring holding member <NUM> are made of a material with a flame retardancy of V-<NUM> according to the UL94 standard. As a result, even if ignition occurs due to tracking, the fire does not spread to parts with low flame retardancy. It is thus possible to provide a process cartridge and an image forming apparatus that ensure safety.

In the present embodiment, the protruding sections of the non-drive-side cartridge cover member <NUM> surround the electrode member <NUM>, but the configuration is not limited to this. A protruding section may protrude from the contact spring holding member <NUM> in the Z2 direction and surround the electrode member <NUM>. In the present embodiment, the non-drive-side cartridge cover member <NUM> and the contact spring holding member <NUM> have a flame retardancy of V-<NUM> according to the UL94 standard, but these members may have a flame retardancy of V-<NUM> or higher.

The process cartridge configuration and the drum cartridge configuration of the first to third embodiments can achieve the same effects of weight reduction and fire spreading prevention in a configuration in which these configurations are bound to the apparatus main body of the image forming apparatus in a nonremovable manner. As such, the process cartridge configuration and the drum cartridge configuration of the first to third embodiments are applicable to a configuration in which these configurations are bound to the image forming apparatus in a nonremovable manner.

In such a configuration, the use of an HB material that is a low-density resin material reduces the overall weight of the image forming apparatus, achieving both the safety and weight reduction of the image forming apparatus. As a result, the impact value of the image forming apparatus main body during physical distribution can be lowered. This allows the packaging of the image forming apparatus to be smaller, improving the distribution efficiency.

Claim 1:
A cartridge (B) to be used in an apparatus main body (A) of an image forming apparatus, the cartridge (B) comprising:
a process unit (<NUM>, <NUM>) to be used to form an image;
a first member (<NUM>) including a first resin material;
a second member (<NUM>) including a second resin material having higher flame retardant capability than the first resin material; and
an electrode member (<NUM>) including a contact section (1701a) configured to be supplied with power from the apparatus main body (A) of the image forming apparatus, the electrode member (<NUM>) being configured to electrically connect with the process unit (<NUM>, <NUM>), wherein
the first member (<NUM>) is a part of a frame of the cartridge (B),
wherein the second resin material of the second member (<NUM>) has a greater density than the first resin material of the first member (<NUM>), and
at least a part of the second member (<NUM>) is located at a position closer to the contact section (1701a) than a part of the first member (<NUM>) closest to the contact section (1701a) and between the contact section (1701a) and the part of the first member (<NUM>) closest to the contact section (1701a).