Patent Description:
Electro-photographic image forming apparatuses, such as laser printers and LED printers, have been developed. A developing cartridge is used in an image forming apparatus. The developing cartridge includes a developing roller for supplying a developer material. An existing image forming apparatus is described in, for example, PTL <NUM>.

The developing cartridge described in PTL <NUM> is mounted on a drum cartridge. The drum cartridge includes a photosensitive drum. When the developing cartridge is mounted on the drum cartridge, the photosensitive drum is brought into contact with the developing roller. Thereafter, the drum cartridge having the developing cartridge mounted therein is mounted in the image forming apparatus.

[PTL <NUM>] <CIT> <CIT> discloses a developing device, process unit, and image forming apparatus.

<CIT> discloses a cartridge, member constituting cartridge, and image forming apparatus.

The drum cartridge includes one member configured to press the developing cartridge toward the photosensitive drum. In addition, the drum cartridge may include another member configured to supply a developing electrode for the developing roller with bias voltage. However, if one member configured to press the developing cartridge toward the photosensitive drum and another member configured to supply a developing electrode for the developing roller with bias voltage are separately provided, the number of parts in the drum cartridge increases.

Accordingly, the object of the present disclosure is to provide a structure capable of reducing the number of parts in a drum cartridge.

A first disclosure of the present application is characterized by a structure comprising a drum cartridge and a developing cartridge as defined in claim <NUM>.

A second disclosure of the present application is characterized in that, in the structure according to the first disclosure, the electrically conductive resilient member is configured to apply pressure to the movable member toward the photosensitive drum.

A third disclosure of the present application is characterized in that in the structure according to the first or second disclosure, the casing extends in a second direction that crosses the first direction, the developing roller is located at one end of the casing in the second direction, and the second end portion of the developing electrode is farther away in the second direction from the one end of the casing than the first end portion is from the one end of the casing.

A fourth disclosure of the present application is characterized in that in the structure according to the third disclosure, the developing electrode is pivotable about a rotation axis extending in the first direction with respect to the first end portion.

An fifth disclosure of the present application is characterized in that in the structure according to the fourth disclosure, the developing electrode is pivotable about the rotation axis between a first position and a second position, the casing has a first restricting surface that is in contact with the second end portion of the developing electrode when the developing electrode is located at the first position and a second restricting surface that is in contact with the second end portion of the developing electrode when the developing electrode is located at the second position.

A sixth disclosure of the present application is characterized in that in the structure according to the fourth disclosure, the second end portion of the developing electrode has a hole extending in the first direction, the casing includes a casing shaft inserted into the hole, and a length of the hole is longer than a length of the casing shaft in a pivotal direction of the second end portion about the rotation axis.

A seventh disclosure of the present application is characterized in that in the structure according to the sixth disclosure, the hole has a first inner side surface and a second inner side surface away from the first inner side surface in the pivotal direction, the casing shaft is in contact with the first inner side surface when the developing electrode is located at the first position, and the casing shaft is in contact with the second inner side surface when the developing electrode is located at the second position.

An eighth disclosure of the present application is characterized in that in the structure according to any one of the first disclosure to the seventh disclosure, the developing roller shaft is electrically conductive.

A ninth disclosure of the present application is characterized in that in the structure according to any one of the first disclosure to the eighth disclosure, the developing electrode is electrically conductive.

A tenth disclosure of the present application is characterized in that in the structure according to the ninth disclosure, the developing electrode is made of a conductive resin.

An eleventh disclosure of the present application is characterized in that in the structure according to any one of the first disclosure to tenth disclosure, the casing has a first outer surface located at one end thereof in the first direction, and the developing electrode extends along the first outer surface between the first end portion and the second end portion.

A twelfth disclosure of the present application is characterized by the structure according to the eleventh disclosure, the developing electrode serves as a first bearing that rotatably supports the developing roller shaft.

A thirteenth disclosure of the present application is characterized in that in the structure according to any one of the first disclosure to the eleventh disclosures, the developing electrode has a shaft hole that extends in the first direction and that has a cylindrical inner peripheral surface, and the developing roller shaft is inserted into the shaft hole.

A fourteenth disclosure of the present application is characterized in that in the structure according to the twelfth disclosure, the casing further has a second outer surface located at the other end thereof in the first direction, and the developing cartridge further includes a second bearing extending between a third end portion and a fourth end portion located farther away from the developing roller shaft than the third end portion is from the developing roller shaft, and the second bearing is pivotable about the rotation axis with respect to the casing.

An fifteenth disclosure of the present application is characterized in that in the structure according to any one of first disclosure to the fourteenth disclosure, when the developing cartridge is mounted on the drum cartridge, the first end portion of the developing electrode is in contact with one portion of the drum cartridge.

A sixteenth disclosure of the present application is characterized in that in the structure according to the fiftheenth disclosure, when the developing cartridge is mounted on the drum cartridge, the second end portion of the developing electrode is in contact with an other portion of the drum cartridge.

According to the first to nineteenth disclosure disclosures of the present application, a bias voltage can be supplied the developing electrode of the developing cartridge via the movable member of the drum cartridge. As a result, the number of parts of the drum cartridge can be reduced as compared with the case where an electrically conductive member for supplying the developing electrode with the bias voltage is provided separately from the movable member.

Embodiments of the present disclosure are described below with reference to the accompanying drawings.

Hereinafter, the direction in which a developing roller <NUM> of a developing cartridge <NUM> extends is referred to as a "first direction". In addition, the direction between which an agitator <NUM> and the developing roller <NUM> of the developing cartridge <NUM> are arranged is referred to as a "second direction". The first direction and the second direction cross (preferably, orthogonally cross) each other.

<FIG> is a perspective view of the developing cartridge <NUM> and the drum cartridge <NUM>. <FIG> is a perspective view of the developing cartridge <NUM> mounted on the drum cartridge <NUM>. The developing cartridge <NUM> and the drum cartridge <NUM> are used in an electro-photographic image forming apparatus. An example of the image forming apparatus is a laser printer or an LED printer.

As illustrated in <FIG> and <FIG>, the developing cartridge <NUM> is used together with the drum cartridge <NUM>. The developing cartridge <NUM> is mountable on the drum cartridge <NUM>. The developing cartridge <NUM> is mounted on the drum cartridge <NUM> and, thereafter, is mounted in the image forming apparatus. The image forming apparatus allows, for example, four developing cartridges <NUM> to be mounted therein. The four developing cartridges <NUM> contain developer materials (for example, toner) of different colors (for example, cyan, magenta, yellow, and black). The image forming apparatus forms an image on a recording surface of print paper by using the developer materials supplied from the developing cartridges <NUM>. Note that the number of developing cartridges <NUM> mountable in the image forming apparatus may be one or more and so, in addition to being four, may be one to three, or five or more.

<FIG> is an exploded perspective view of the developing cartridge <NUM>. <FIG> is a view of the developing cartridge <NUM>, in particular an exploded perspective view, in the vicinity of a first outer surface <NUM> of a casing <NUM>. <FIG> is a view of the developing cartridge <NUM>, in particular an exploded perspective view in the vicinity of a second outer surface <NUM> of the casing <NUM>. As illustrated in <FIG>, the developing cartridge <NUM> includes the casing <NUM>, the agitator <NUM>, the developing roller <NUM>, a supply roller <NUM>, a gear unit <NUM>, a first bearing <NUM>, and a second bearing <NUM>. The first bearing <NUM> is also a developing electrode <NUM>.

The casing <NUM> is a casing capable of containing a developer material. The casing <NUM> has the first outer surface <NUM> and the second outer surface <NUM>. The first outer surface <NUM> is located at one end of the casing <NUM> in the first direction. The second outer surface <NUM> is located at the other end of the casing <NUM> in the first direction. The first outer surface <NUM> and the second outer surface <NUM> are separated from each other in the first direction. The casing <NUM> extends in the first direction between the first outer surface <NUM> and the second outer surface <NUM>. In addition, the casing <NUM> extends in the second direction.

The casing <NUM> has an accommodation chamber <NUM> provided thereinside. The developer material is stored in the accommodation chamber <NUM>. In addition, the casing <NUM> has an opening <NUM>. The opening <NUM> is located at one end 10a of the casing <NUM> in the second direction. The outside of the casing <NUM>, in other words the external space, and the accommodation chamber <NUM> of the casing <NUM> communicate with each other through the opening <NUM>. Note that the casing <NUM> may have a handle on the outer surface at the other end 10b in the second direction.

The agitator <NUM> includes an agitator shaft <NUM> and a blade <NUM>. The agitator shaft <NUM> extends in the first direction. The blade <NUM> extends or expands from the agitator shaft <NUM> toward the inner surface of the casing <NUM>. The blade <NUM> and part of the agitator shaft <NUM> are disposed in the accommodation chamber <NUM> of the casing <NUM>. An agitator gear <NUM> included in the gear unit <NUM> is attached to one end of the agitator shaft <NUM> in the first direction. The agitator shaft <NUM> is fixed to the agitator gear <NUM> so as not to rotate relative to the agitator gear. When the agitator gear <NUM> rotates, the agitator shaft <NUM> and the blade <NUM> rotate about the rotation axis extending in the first direction. Thus, the developer material is agitated in the accommodation chamber <NUM> by the blade <NUM> that is rotating.

The developing roller <NUM> is a roller that can rotate about a rotation axis (a first axis) A1 extending in the first direction. The developing roller <NUM> is located in the opening <NUM> of the casing <NUM>. That is, the developing roller <NUM> is located at the one end of the casing <NUM> in the second direction. The developing roller <NUM> includes a developing roller main body <NUM> and a developing roller shaft <NUM>. The developing roller main body <NUM> is a cylindrical member extending in the first direction. As the material used for the developing roller main body <NUM>, rubber having resilience is used, for example. The developing roller shaft <NUM> is a cylindrical member that extends in the first direction and passes completely through the developing roller main body <NUM>. The developing roller shaft <NUM> is electrically conductive. For the material of the developing roller shaft <NUM>, metal or resin having electrical conductivity is used.

The developing roller main body <NUM> is fixed to the developing roller shaft <NUM> so as not to rotate relative to the developing roller shaft <NUM>. Furthermore, a developing roller gear <NUM> included in the gear unit <NUM> is attached to an end portion of the developing roller shaft <NUM> in the first direction. The developing roller shaft <NUM> is fixed to the developing roller gear <NUM> so as not to rotate relative to the developing roller gear <NUM>. Accordingly, when the developing roller gear <NUM> rotates, the developing roller shaft <NUM> rotates, and the developing roller main body <NUM> also rotates together with the developing roller shaft <NUM>.

Note that the developing roller shaft <NUM> need not pass completely through the developing roller main body <NUM> in the first direction. For example, the developing roller shaft <NUM> may comprise two respective parts that extend in the first direction from both ends of the developing roller main body <NUM> in the first direction.

The supply roller <NUM> is a roller that is rotatable about a rotation axis (a second axis) extending in the first direction. The supply roller <NUM> is located between the agitator <NUM> and the developing roller <NUM>. The supply roller <NUM> includes a supply roller main body <NUM> and a supply roller shaft <NUM>. The supply roller main body <NUM> is a cylindrical member extending in the first direction. As the material used for the supply roller main body <NUM>, rubber having resilience is used, for example. The supply roller shaft <NUM> is a columnar member extending in the first direction so as to pass completely through the supply roller main body <NUM>.

The supply roller main body <NUM> is fixed to the supply roller shaft <NUM> so as not to rotate relative to the supply roller shaft <NUM>. In addition, a supply roller gear <NUM> included in the gear unit <NUM> is attached to an end of the supply roller shaft <NUM> in the first direction. The supply roller shaft <NUM> is fixed to the supply roller gear <NUM> so as not to rotate relative to the supply roller gear. Consequently, if the supply roller gear <NUM> rotates, the supply roller shaft <NUM> also rotates and, thus, the supply roller main body <NUM> also rotates together with the supply roller shaft <NUM>.

Note that the supply roller shaft <NUM> need not pass completely through the supply roller main body <NUM> in the first direction. For example, the supply roller shaft <NUM> may comprise two respective parts that extend in the first direction from both ends of the supply roller main body <NUM> in the first direction.

When the developing cartridge <NUM> receives the driving force, the developer material is supplied from the accommodation chamber <NUM> in the casing <NUM> to the outer peripheral surface of the developing roller <NUM> via the supply roller <NUM>. At this time, the developer material is triboelectrically charged between the supply roller <NUM> and the developing roller <NUM>. In addition, a bias voltage is applied to the developing roller shaft <NUM> of the developing roller <NUM>. For this reason, the developer material is attracted to the outer peripheral surface of the developing roller main body <NUM> by the electrostatic force between the developing roller shaft <NUM> and the developer material.

Furthermore, the developing cartridge <NUM> includes a layer thickness regulation blade (not illustrated). The layer thickness regulation blade shapes the developer material supplied onto the outer peripheral surface of the developing roller main body <NUM> into a predetermined thickness. Thereafter, the developer material on the outer peripheral surface of the developing roller main body <NUM> is supplied to a photosensitive drum <NUM> (described below) of the drum cartridge <NUM>. At this time, the developer material moves from the developing roller main body <NUM> onto the photosensitive drum <NUM> in accordance with an electrostatic latent image formed on the outer peripheral surface of the photosensitive drum <NUM>. In this manner, the electrostatic latent image is visualized on the outer peripheral surface of the photosensitive drum <NUM>.

The gear unit <NUM> is located on the second outer surface <NUM> of the casing <NUM>. As illustrated in <FIG>, the gear unit <NUM> includes the above-described agitator gear <NUM>, developing roller gear <NUM>, and supply roller gear <NUM>, a plurality of idle gears <NUM>, a coupling <NUM>, and a gear cover <NUM>. The gear cover <NUM> and the cover <NUM> together constitute the overall casing of the developing cartridge <NUM> together with the casing <NUM>. The gear cover <NUM> is fixed to the second outer surface <NUM> of the casing <NUM> by, for example, screwing. At least some of the plurality of gears are located between the second outer surface <NUM> and the gear cover <NUM>.

The coupling <NUM> has an engagement portion <NUM> recessed in the first direction. The engagement portion <NUM> is exposed through the gear cover <NUM>. When the developing cartridge <NUM> mounted on the drum cartridge <NUM> is mounted in an image forming apparatus having a drive shaft, the drive shaft of the image forming apparatus is connected to the engagement portion <NUM> of the coupling <NUM>. Thus, the rotation of the drive shaft of the image forming apparatus is transmitted to the agitator gear <NUM>, the plurality of idle gears <NUM>, the developing roller gear <NUM>, and the supply roller gear <NUM> via the coupling <NUM>.

The plurality of gears included in the gear unit <NUM> may transmit the rotational force by meshing of teeth or may transmit the rotational force by friction.

<FIG> is a view of the developing cartridge <NUM> in particular an exploded front view in the vicinity of the first outer surface <NUM> of the casing <NUM>. As illustrated in <FIG>, <FIG> and <FIG>, the first bearing <NUM> is located on the first outer surface <NUM> of the casing <NUM>. The first bearing <NUM> rotatably supports one end of the developing roller shaft <NUM> in the first direction.

The first bearing <NUM> has a first end portion <NUM> and a second end portion <NUM>. The second end portion <NUM> is farther away from the developing roller shaft <NUM> than the first end portion <NUM> is to the developing roller shaft <NUM>. In addition, the second end portion <NUM> is farther away in the second direction from the one end 10a of the casing <NUM> in the second direction than the first end portion <NUM> is to the one end 10a of the casing <NUM> in the second direction. The first bearing <NUM> extends along the first outer surface <NUM> of the casing <NUM> between the first end portion <NUM> and the second end portion <NUM>.

The first bearing <NUM> includes a first arm <NUM> and a second arm <NUM>. The second arm <NUM> is farther away from the developing roller shaft <NUM> than the first arm <NUM>. In addition, the second arm <NUM> is farther away from the one end 10a in the second direction of the casing <NUM> than the first arm <NUM> is to the one end 10a in the second direction. The first arm <NUM> has the first end portion <NUM> described above. The second arm <NUM> has the second end portion <NUM> described above. The first arm <NUM> extends along the first outer surface <NUM> of the casing <NUM>, for example, linearly. The second arm <NUM> extends along the first outer surface <NUM> of the casing <NUM>, for example, linearly. Note that the first arm <NUM> is at an angle to the second arm <NUM>. The angle formed by the first arm <NUM> and the second arm <NUM> is an obtuse angle.

According to the present embodiment, the first arm <NUM> and the second arm <NUM> are integrally formed. However, the first arm <NUM> and the second arm <NUM> may be separate parts. In this case, the first arm <NUM> and the second arm <NUM> can be fixed to each other.

The first bearing <NUM> has a first shaft hole <NUM>. The first shaft hole <NUM> extends in the first direction in the first end portion <NUM> of the first bearing <NUM>. The first shaft hole <NUM> may be a through-hole passing through the first end portion <NUM> in the first direction. Alternatively, the first shaft hole <NUM> may be a hole that does not pass through the first end portion <NUM>. The first shaft hole <NUM> has a cylindrical inner peripheral surface. One end of the developing roller shaft <NUM> in the first direction is inserted into the first shaft hole <NUM>. Thus, the one end of the developing roller shaft <NUM> in the first direction is supported so as to be rotatable about a rotation axis (a first axis) A1 extending in the first direction. In addition, the first bearing <NUM> is pivotable about the rotation axis A1 with respect to the casing <NUM>. More specifically, the second end portion <NUM> is pivotable about the rotation axis A1 with respect to the first end portion <NUM>.

The first bearing <NUM> serves as an electrically conductive member which, because it provides electrical connection to the developing roller shaft <NUM>, is described herein as a developing electrode. The first bearing <NUM> is made of, for example, a conductive resin. However, the first bearing <NUM> may be made of metal. The first end portion <NUM> of the first bearing <NUM> is in contact with the one end of the developing roller shaft <NUM> in the first direction. Consequently, the first end portion <NUM> of the first bearing <NUM> is electrically connected to the developing roller shaft <NUM>. Alternatively, the first bearing <NUM> may be a pivotable member. The pivotable member may be configured to electrically connected to the developing roller shaft <NUM>. Preferably, the first pivotable member may be a pivotable lever.

As illustrated in <FIG>, the casing <NUM> has a casing recess <NUM>. The inner surface of the casing recess <NUM> includes a first restricting surface <NUM> and a second restricting surface <NUM>. The first restricting surface <NUM> and the second restricting surface <NUM> are separated from each other in the rotational direction of the second end portion <NUM> about the rotation axis A1. In addition, as illustrated in <FIG>, the first bearing <NUM> has a protrusion, for example having a rod-like shape, described herein as a bearing shaft <NUM>. The bearing shaft <NUM> protrudes from the second end portion <NUM> of the first bearing <NUM> toward the other side in the first direction. The bearing shaft <NUM> is inserted into the casing recess <NUM>.

<FIG> illustrates how the first bearing <NUM> pivots. The first bearing <NUM> is pivotable about the rotation axis A1 between a first position illustrated in the upper section of <FIG> and a second position illustrated in the lower section of <FIG>. When the first bearing <NUM> is located at the first position, the bearing shaft <NUM> is in contact with the first restricting surface <NUM>. In contrast, when the first bearing <NUM> is located at the second position, the bearing shaft <NUM> is in contact with the second restricting surface <NUM>. In this manner, the pivot range of the first bearing <NUM> about the rotation axis A1 is restricted.

In addition, the first bearing <NUM> has a first hole <NUM>. The first hole <NUM> extends in the second direction between the first end portion <NUM> and the second end portion <NUM>. Furthermore, the first hole <NUM> passes completely through the first bearing <NUM> in a pivotal direction about the rotation axis A1. However, the first hole <NUM> need not pass completely through the first bearing <NUM>. When the developing cartridge <NUM> is mounted on the drum cartridge <NUM>, the first hole <NUM> allows a first lever <NUM> (described below) of the drum cartridge <NUM> to be inserted thereinto.

As illustrated in <FIG>, the second bearing <NUM> is located on the second outer surface <NUM> of the casing <NUM>. More specifically, the second bearing <NUM> is located on the outer surface of the gear cover <NUM>. The first bearing <NUM> and the second bearing <NUM> are located so as to overlap each other, as viewed in the first direction. The second bearing <NUM> rotatably supports the other end of the developing roller shaft <NUM> in the first direction. The second bearing <NUM> has a third end portion <NUM> and a fourth end portion <NUM>. The fourth end portion <NUM> is farther away from the developing roller shaft <NUM> than the third end portion <NUM>. In addition, the fourth end portion <NUM> is farther away in the second direction from the one end 10a of the casing <NUM> in the second direction than the third end portion <NUM> is to the one end 10a of the casing <NUM> in the second direction. The second bearing <NUM> extends along the second outer surface <NUM> of the casing <NUM> between the third end portion <NUM> and the fourth end portion <NUM>.

The second bearing <NUM> includes a third arm <NUM> and a fourth arm <NUM>. The fourth arm <NUM> is farther away from the developing roller shaft <NUM> than the third arm <NUM>. In addition, the fourth arm <NUM> is farther away in the second direction from the one end 10a of the casing <NUM> in the second direction than the third arm <NUM> is to the one end 10a of the casing <NUM> in the second direction. The third arm <NUM> has the third end portion <NUM> described above. The fourth arm <NUM> has the fourth end portion <NUM> described above. The third arm <NUM> extends along the second outer surface <NUM> of the casing <NUM>, for example, linearly. The fourth arm <NUM> extends along the second outer surface <NUM> of the casing <NUM>, for example, linearly. However, the third arm <NUM> is at an angle to the fourth arm <NUM>. The angle formed by the third arm <NUM> and the fourth arm <NUM> is an obtuse angle.

According to the present embodiment, the third arm <NUM> and the fourth arm <NUM> are integrally formed. However, the third arm <NUM> and the fourth arm <NUM> may be separate parts. In this case, it is only required that the third arm <NUM> and the fourth arm <NUM> are fixed to each other.

The second bearing <NUM> has a second shaft hole <NUM>. The second shaft hole <NUM> extends in the first direction in the third end portion <NUM> of the second bearing <NUM>. The second shaft hole <NUM> may be a through-hole passing through the third end portion <NUM> in the first direction. Alternatively, the second shaft hole <NUM> may be a hole that does not pass through the third end portion <NUM>. The second shaft hole <NUM> has a cylindrical inner circumferential surface. The other end of the developing roller shaft <NUM> in the first direction is inserted into the second shaft hole <NUM>. In this manner, the other end of the developing roller shaft <NUM> in the first direction is supported in a rotatable manner about a rotation axis (a first axis) A1 extending in the first direction. In addition, the second bearing <NUM> is also pivotable about the rotation axis A1 with respect to the casing <NUM>. More specifically, the fourth end portion <NUM> is pivotable about the rotation axis A1 with respect to the third end portion <NUM>.

As illustrated in <FIG>, the gear cover <NUM> has a gear cover projection <NUM>. The gear cover projection <NUM> protrudes from the gear cover <NUM> toward the other side in the first direction. In addition, the second bearing <NUM> has a hook portion <NUM>. The hook portion <NUM> protrudes from the outer surface of the second bearing <NUM> in the rotational direction of the fourth end portion <NUM> about the rotation axis A1. Furthermore, the second bearing <NUM> has a third restricting surface <NUM> located at the base end of the hook portion <NUM> and a fourth restricting surface <NUM> located at the top end of the hook portion <NUM>. The third restricting surface <NUM> and the fourth restricting surface <NUM> are separated from each other in the pivotal direction of the fourth end portion <NUM> about the rotation axis A1.

The second bearing <NUM> is pivotable about the rotation axis A1 between the third position and the fourth position. When the second bearing <NUM> is located at the third position, the third restricting surface <NUM> of the second bearing <NUM> is in contact with the gear cover projection <NUM>. In contrast, when the second bearing <NUM> is located at the fourth position, the fourth restricting surface <NUM> of the second bearing <NUM> is in contact with the gear cover projection <NUM>. In this manner, the rotation range of the second bearing <NUM> is restricted.

In addition, the second bearing <NUM> has a third hole <NUM>. The third hole <NUM> extends in the second direction between the third end portion <NUM> and the fourth end portion <NUM>. Furthermore, the third hole <NUM> passes completely through the second bearing <NUM> in a pivotal direction about the rotation axis A1. However, the third hole <NUM> need not pass completely through the second bearing <NUM>. When the developing cartridge <NUM> is mounted on the drum cartridge <NUM>, the third hole <NUM> allows a second lever (described below) of the drum cartridge <NUM> to be inserted thereinto. The first hole <NUM> of the first bearing <NUM> and the third hole <NUM> of the second bearing <NUM> are located so as to overlap each other, as viewed in the first direction.

As illustrated in <FIG> and <FIG>, the drum cartridge <NUM> includes the drum frame <NUM> and the photosensitive drum <NUM>. The developing cartridge <NUM> is mounted on the drum frame <NUM>. The photosensitive drum <NUM> is a cylindrical drum which is rotatable about a rotation axis extending in the first direction. The outer peripheral surface of the photosensitive drum <NUM> is coated with a photosensitive material. The photosensitive drum <NUM> is located at one end of the drum frame <NUM> in the second direction. When the developing cartridge <NUM> is mounted on the drum frame <NUM>, the outer peripheral surface of the developing roller <NUM> is in contact with the outer peripheral surface of the photosensitive drum <NUM>.

<FIG> are cross-sectional views of the developing cartridge <NUM> and the drum cartridge <NUM> when the developing cartridge <NUM> is mounted on the drum cartridge <NUM>. <FIG> are cross-sectional views of the developing cartridge <NUM> and the drum cartridge <NUM> taken along a break line S - S of <FIG>. As illustrated in <FIG>, the drum cartridge <NUM> has a first guide surface <NUM> and a second guide surface <NUM>. The first guide surface <NUM> and the second guide surface <NUM> are located at one end of the drum frame <NUM> in the first direction. In addition, the first guide surface <NUM> and the second guide surface <NUM> are separated in the rotational direction about the rotation axis of the photosensitive drum <NUM>. Note that the drum cartridge <NUM> further has a third guide surface (not illustrated) and a fourth guide surface (not illustrated) that are similar to the first guide surface <NUM> and the second guide surface <NUM>, respectively, at the other end of the drum frame <NUM> in the first direction.

Furthermore, as illustrated in <FIG>, the drum cartridge <NUM> includes a first movable member <NUM> and a first coil spring <NUM>. The first movable member <NUM> and the first coil spring <NUM> are electrically conductive. The first movable member <NUM> is made of, for example, a conductive resin. The first coil spring <NUM> is made of, for example, metal. The first movable member <NUM> and the first coil spring <NUM> are located at one end of the drum frame <NUM> in the first direction. The first coil spring <NUM> is a resilient member that can expand and contract in the second direction. One end of the first coil spring <NUM> in the second direction is connected to the first movable member <NUM>. The other end of the first coil spring <NUM> in the second direction is connected to the drum frame <NUM>. With the developing cartridge <NUM> mounted on the drum cartridge <NUM>, the first movable member <NUM> applies pressure to the second end portion <NUM> of the first bearing <NUM> toward the photosensitive drum <NUM> by the resilience force of the first coil spring <NUM>.

In addition, the drum cartridge <NUM> includes a second movable member (not illustrated) and a second coil spring (not illustrated). The second movable member and the second coil spring are located at the other end of the drum frame <NUM> in the first direction. With the developing cartridge <NUM> mounted on the drum cartridge <NUM>, the second movable member applies a pressure to the fourth end portion <NUM> of the second bearing <NUM> toward the photosensitive drum <NUM> by the resilience force of the second coil spring.

Note that instead of using the first coil spring <NUM> and the second coil spring, other types of resilient members may be used for the drum cartridge <NUM>. For example, the drum cartridge <NUM> may be provided with a spring other than a coil spring (e.g., a torsion spring or a leaf spring), rubber, or the like) as the resilient member.

In addition, as illustrated in <FIG>, the drum cartridge <NUM> includes a first lever <NUM>. The first lever <NUM> is located at one end of the drum frame <NUM> in the first direction. The first lever <NUM> is located between the first movable member <NUM> and the photosensitive drum <NUM>. The first lever <NUM> is pivotable about a rotation shaft extending in the first direction. When the developing cartridge <NUM> is mounted on the drum cartridge <NUM>, the first lever <NUM> is inserted into, and so located in, the first hole <NUM> of the first bearing <NUM>.

In addition, the drum cartridge <NUM> includes a second lever (not illustrated). The second lever is located at the other end of the drum frame <NUM> in the first direction. The second lever is located between the second movable member and the photosensitive drum <NUM>. The second lever is pivotable about a rotation shaft extending in the first direction. When the developing cartridge <NUM> is mounted on the drum cartridge <NUM>, the second lever is inserted into, and so located in, the third hole <NUM> of the second bearing <NUM>.

As illustrated in <FIG>, when the developing cartridge <NUM> is mounted on the drum cartridge <NUM>, the developing cartridge <NUM> is moved relative to the drum cartridge <NUM> so that the developing roller <NUM> moves close to the photosensitive drum <NUM>. At this time, as illustrated in <FIG>, the first end portion <NUM> of the first bearing <NUM> is brought into contact with the second guide surface <NUM> and moves along the second guide surface <NUM>. Accordingly, the first bearing <NUM> pivots about the rotation axis A1 from the first position to the second position. Similarly, the third end portion <NUM> of the second bearing <NUM> is brought into contact with the fourth guide surface and moves along the fourth guide surface. Accordingly, the second bearing <NUM> pivots about the rotation axis A1 from the third position to the fourth position.

As described above, when the developing cartridge <NUM> is mounted on the drum cartridge <NUM>, the first bearing <NUM> and the second bearing <NUM> pivot about the rotation axis A1 of the developing roller <NUM>. As a result, without rotating the casing <NUM> with respect to the drum frame <NUM>, the first bearing <NUM> can be placed between the photosensitive drum <NUM> and the first movable member <NUM>. In addition, the second bearing <NUM> can be placed between the photosensitive drum <NUM> and the second movable member. Consequently, a user of the cartridges and the image forming apparatus can move the developing roller <NUM> close to the photosensitive drum <NUM> without performing the operation to rotate the casing <NUM>.

With the first bearing <NUM> placed between the photosensitive drum <NUM> and the first movable member <NUM>, the first movable member <NUM> is in contact with the second end portion <NUM> of the first bearing <NUM>. At this time, the first movable member <NUM> applies pressure to the second end portion <NUM> of the first bearing <NUM> toward the photosensitive drum <NUM> by the resilience force of the first coil spring <NUM>. Then, as illustrated in <FIG>, the first end portion <NUM> of the first bearing <NUM> is brought into contact with the first guide surface <NUM>, and the second end portion <NUM> of the first bearing <NUM> is brought into contact with the second guide surface <NUM>. In this manner, the position of the first bearing <NUM> relative to the drum frame <NUM> is fixed.

Similarly, the second movable member applies pressure to the fourth end portion <NUM> of the second bearing <NUM> toward the photosensitive drum <NUM>. At this time, the third end portion <NUM> of the second bearing <NUM> is brought into contact with the third guide surface, and the fourth end portion <NUM> of the second bearing <NUM> is brought into contact with the fourth guide surface. In this manner, the position of the second bearing <NUM> relative to the drum frame <NUM> is fixed.

Furthermore, the first movable member <NUM> applies pressure to the first bearing <NUM> with the positions of the first bearing <NUM> and the second bearing <NUM> relative to the drum frame <NUM> fixed. In addition, the second movable member applies pressure to the second bearing <NUM>. Thus, the outer peripheral surface of the developing roller <NUM> is brought into contact with the outer peripheral surface of the photosensitive drum <NUM>. In this manner, the developing roller <NUM> is urged against the photosensitive drum <NUM>.

As described above, according to the present embodiment, the first bearing <NUM> has the first end portion <NUM> and the second end portion <NUM>, and the second end portion <NUM> is pivotable with respect to the first end portion <NUM>. In addition, the second bearing <NUM> has the third end portion <NUM> and the fourth end portion <NUM>, and the fourth end portion <NUM> is pivotable with respect to the third end portion <NUM>. Consequently, the positioning of the developing roller <NUM> relative to the photosensitive drum <NUM> can be achieved by using the first end portion <NUM> and the second end portion <NUM> of the first bearing <NUM> and the third end portion <NUM> and the fourth end portion <NUM> of the second bearing <NUM>.

Furthermore, according to the present embodiment, when the developing cartridge <NUM> is being mounted on the drum cartridge <NUM>, the first bearing <NUM> and the second bearing <NUM> pivot about the rotation axis A1. In addition, when the developing cartridge <NUM> is being removed from the drum cartridge <NUM>, the first bearing <NUM> and the second bearing <NUM> pivot about the rotation axis A1 in the same manner. For this reason, the developing cartridge <NUM> can be smoothly mounted on or removed from the drum cartridge <NUM> by causing the first bearing <NUM> and the second bearing <NUM> to pivot without rotating the casing <NUM>.

<FIG> is a side view of the developing cartridge <NUM> and the drum cartridge <NUM> with the developing cartridge <NUM> mounted on the drum cartridge <NUM>. Note that in <FIG>, the drum frame <NUM> is denoted by a two-dot chain line.

The first movable member <NUM> and the first coil spring <NUM> are electrically conductive. The first movable member <NUM> is made of, for example, a conductive resin. The first coil spring <NUM> is made of, for example, metal. In addition, as illustrated in <FIG>, the drum cartridge <NUM> includes an electrode terminal <NUM> that is in electrical contact with the first coil spring <NUM>. As illustrated in <FIG> and <FIG>, the electrode terminal <NUM> is exposed on the outer surface of the drum frame <NUM>. Furthermore, as described above, the developing roller shaft <NUM> and the first bearing <NUM> are electrically conductive. For this reason, when the developing cartridge <NUM> is mounted on the drum cartridge <NUM> and, thus, the first movable member <NUM> is brought into contact with the first bearing <NUM>, the electrode terminal <NUM>, the first coil spring <NUM>, the first movable member <NUM>, the first bearing <NUM>, and the developing roller shaft <NUM> are electrically connected to one another.

When the developing cartridge <NUM> mounted on the drum cartridge <NUM> is mounted in the image forming apparatus, the electrode terminal of the image forming apparatus is in contact with the electrode terminal <NUM> of the drum cartridge <NUM>. Thus, a bias voltage is supplied from the image forming apparatus to the developing roller shaft <NUM> via the electrode terminal <NUM>, the first coil spring <NUM>, the first movable member <NUM>, and the first bearing <NUM>. As a result, the developer material is attracted to the outer peripheral surface of the developing roller main body <NUM> by the electrostatic force generated by the bias voltage.

As described above, according to the present embodiment, the bias voltage is supplied to the first bearing <NUM> of the developing cartridge <NUM> via the first movable member <NUM> of the drum cartridge <NUM>. In this way, the number of parts of the drum cartridge <NUM> can be reduced as compared with the case where a conductive part for supplying a voltage to the first bearing <NUM> is provided separately from the first movable member <NUM>. Therefore, the size of the drum cartridge <NUM> can be reduced.

In addition, the first bearing <NUM> according to the present embodiment has (<NUM>) the capability of serving as a bearing for rotatably supporting the developing roller shaft <NUM> and (<NUM>) the capability of serving as a positioning member that determines the position of the developing roller <NUM> relative to the photosensitive drum <NUM> when the developing cartridge <NUM> is mounted on the drum cartridge <NUM> and (<NUM>) the capability of serving as a developing electrode for supplying a bias voltage to the developing roller shaft <NUM>. For this reason, the number of parts in the developing cartridge <NUM> can be reduced as compared with the case where these capabilities are provided by using different members. In addition, the size of the developing cartridge <NUM> can be reduced.

After the developing cartridge <NUM> mounted on the drum cartridge <NUM> is mounted in the image forming apparatus, the developing cartridge <NUM> can perform a separating operation by the driving force supplied from the image forming apparatus. As used herein, the term "separating operation" refers to an operation to temporarily separate the developing roller <NUM> from the photosensitive drum <NUM>. For example, when monochrome printing is performed in the image forming apparatus, the developing cartridges <NUM> of colors other than black perform the separating operation. Note that the developing cartridge <NUM> of black color may perform the separating operation.

As illustrated in <FIG>, when the developing cartridge <NUM> is mounted on the drum cartridge <NUM>, the developing cartridge <NUM> is disposed at a contact position at which the developing roller <NUM> is in contact with the photosensitive drum <NUM>. At this time, the first lever <NUM> of the drum cartridge <NUM> is inserted into the first hole <NUM> of the first bearing <NUM>. In addition, a second lever (not illustrated) of the drum cartridge <NUM> is inserted into the third hole <NUM> of the second bearing <NUM>.

<FIG> is a side view of the drum cartridge <NUM>. In <FIG>, the drum frame <NUM> is denoted by a two-dot chain line. As illustrated in <FIG>, the drum cartridge <NUM> includes a first cam <NUM>. The first cam <NUM> is located between the photosensitive drum <NUM> and the first lever <NUM> in the second direction. In addition, the first cam <NUM> is located between each of the above-described first guide surface <NUM> and second guide surface <NUM> and the drum frame <NUM> in the first direction. When the separation operation is performed, the first cam <NUM> pivots about a rotation shaft extending in the first direction by the driving force supplied from the image forming apparatus. Thus, a projection <NUM> of the first cam <NUM> presses a projection <NUM> of the first lever <NUM>. As a result, the first lever <NUM> pivots about the rotation axis extending in the first direction, from a position indicated by the solid line to a position indicated by a two-dot chain line illustrated in <FIG>. In addition, the drum cartridge <NUM> includes a second cam similar to the first cam <NUM> in order to cause the second lever to pivot.

<FIG> is a cross-sectional view of the developing cartridge <NUM> and the drum cartridge <NUM> at the time of the separating operation. <FIG> is a cross-sectional view of the developing cartridge <NUM> and the drum cartridge <NUM> taken along a broken line S - S in <FIG>. When the first lever <NUM> is rotated by the first cam <NUM>, the first lever <NUM> presses an inner surface <NUM> of the first hole <NUM> of the first bearing <NUM>. More specifically, the first lever <NUM> presses the second end portion <NUM> of the first bearing <NUM> in a direction away from the photosensitive drum <NUM> against the pressing force of the first coil spring <NUM>. In addition, when the second lever is caused to pivot by the second cam, the second lever presses the inner surface of the third hole <NUM> of the second bearing <NUM>. More specifically, the second lever presses the fourth end portion <NUM> of the second bearing <NUM> in a direction away from the photosensitive drum <NUM> against the pressing force of the second coil spring.

Thus, the casing <NUM> and the developing roller <NUM> move in the direction away from the photosensitive drum <NUM> together with the first bearing <NUM> and the second bearing <NUM>. As a result, the outer peripheral surface of the developing roller <NUM> is separated from the outer peripheral surface of the photosensitive drum <NUM>. That is, the developing cartridge <NUM> moves from the above-described contact position to the separated position with respect to the drum cartridge <NUM>.

As described above, according to the present embodiment, the developing cartridge <NUM> can be moved from the contact position to the separated position by pressing the first bearing <NUM> and the second bearing <NUM>. For this reason, the number of parts of the developing cartridge <NUM> can be reduced as compared with the case where a member that receives a pressing force at the time of the separation operation is provided separately from the first bearing <NUM> and the second bearing <NUM>. Consequently, the size of the developing cartridge <NUM> can be reduced more.

In addition, the first bearing <NUM> is pivotable about the rotation axis A1. Therefore, the first lever <NUM> can press the inner surface <NUM> of the first hole <NUM> of the first bearing <NUM> in an optimum direction without rotating the casing <NUM>. Similarly, the second bearing <NUM> is pivotable about the rotation axis A1. Therefore, the second lever can press the inner surface of the third hole <NUM> of the second bearing <NUM> in an optimum direction without rotating the casing <NUM>.

In addition, when the developing cartridge <NUM> moves from the contact position to the separated position, the first bearing <NUM> moves along the second guide surface <NUM>. Furthermore, the second bearing <NUM> moves along the fourth guide surface. In this manner, the first lever <NUM> can press the first bearing <NUM> while maintaining the position of the first bearing <NUM> relative to the rotation axis A1 serving as the central point. Furthermore, the second lever can press the second bearing <NUM> while maintaining the position of the second bearing <NUM> relative to the rotation axis A1 serving as the central point.

While an embodiment of the present disclosure has been described above, the present disclosure is not limited to the above-described embodiment. A variety of modifications are described below, focusing on differences between the modifications and the above-described embodiment.

The first modification is a modification relating to a mechanism for operating the first lever <NUM> of the drum cartridge <NUM>. <FIG> is a side view of the drum cartridge <NUM> of the first modification. In <FIG>, the drum frame <NUM> is denoted by a two-dot chain line. In the example of <FIG>, the drum cartridge <NUM> does not include the first cam <NUM>. The first lever <NUM> has a projection <NUM> for receiving a drive from the image forming apparatus. When the separating operation is performed, the image forming apparatus presses the projection <NUM> of the first lever <NUM>. As a result, the first lever <NUM> pivots about a rotation shaft extending in the first direction. As described above, if the need for the first cam <NUM> is eliminated, the number of parts of the developing cartridge <NUM> can be reduced more.

The second modification is another modification relating to a structure for restricting the rotation range of the first bearing <NUM>. <FIG> is a side view of a first bearing <NUM> according to the second modification. In the example of <FIG>, the first bearing <NUM> has a second hole <NUM> in the second end portion <NUM>. The second hole <NUM> extends in the first direction from the surface of the second end portion <NUM> of the first bearing <NUM> on the other side in the first direction toward the surface on the one side in the first direction.

In addition, in the example of <FIG>, a casing <NUM> has a casing shaft <NUM>. The casing shaft <NUM> extends in the first direction from the first outer surface <NUM> of the casing <NUM> toward one side in the first direction. The casing shaft <NUM> is inserted into the second hole <NUM> of the first bearing <NUM>.

As illustrated in <FIG>, a length d1 of the second hole <NUM> is longer than a length d2 of the casing shaft <NUM> in the pivotal direction of the second end portion <NUM> about the rotation axis A1. In addition, the second hole <NUM> has a first inner side surface <NUM> and a second inner side surface <NUM>. The first inner side surface <NUM> and the second inner side surface <NUM> are separated from each other in the above-described pivotal direction.

Like the above-described embodiment, the first bearing <NUM> is pivotable about the rotation axis A1 between a first position (the position denoted by a two-dot chain line illustrated in <FIG>) and a second position (the position denoted by a solid line in <FIG>). When the first bearing <NUM> is located at the first position, the casing shaft <NUM> is in contact with the first inner side surface <NUM>. In contrast, when the first bearing <NUM> is located at the second position, the casing shaft <NUM> is in contact with the second inner side surface <NUM>. Thus, the rotation range of the first bearing <NUM> is restricted.

According to the above-described embodiment, the developing cartridge <NUM> includes the first bearing and the second bearing. The first bearing and the second bearing have the same shape, and both are pivotable with respect to the casing <NUM>. However, the second bearing may have a shape that differs from that of the first bearing. In addition, the second bearing may be non-pivotable with respect to the casing <NUM>. Furthermore, the developing cartridge <NUM> does not necessarily have to include the second bearing. In this case, the first bearing can be placed at either one of the ends of the casing <NUM> in the first direction.

According to the above-described embodiment, the developing cartridge <NUM> is mounted on the drum cartridge <NUM> including only one photosensitive drum <NUM>. However, the developing cartridge <NUM> may be mounted on a drum cartridge including a plurality of photosensitive drums <NUM>.

Claim 1:
A structure comprising a drum cartridge (<NUM>) and a developing cartridge (<NUM>), the drum cartridge (<NUM>) comprising:
a photosensitive drum (<NUM>) rotatable about a shaft extending in a first direction;
an electrically conductive resilient member (<NUM>) being a coil spring;
an electrically conductive movable member (<NUM>); and
an electrode terminal (<NUM>),
the developing cartridge (<NUM>) comprising:
a developing roller (<NUM>) including a developing roller shaft (<NUM>) extending in the first direction;
a casing (<NUM>) capable of containing a developer material; and
a developing electrode (<NUM>) having a first end portion (<NUM>) and a second end portion (<NUM>) located farther away from the developing roller shaft (<NUM>) than the first end portion (<NUM>), the first end portion (<NUM>) configured to be electrically connected to the developing roller shaft (<NUM>),
wherein the movable member (<NUM>) applies pressure to the second end portion of the developing electrode (<NUM>) toward the photosensitive drum (<NUM>) by the resilience force of the electrically conductive resilient member (<NUM>) such that the developing roller (<NUM>) is urged against the photosensitive drum (<NUM>), and
wherein a bias voltage is supplied to the developing roller shaft (<NUM>) via the electrode terminal (<NUM>), the resilient member (<NUM>), the movable member (<NUM>), and the developing electrode (<NUM>).