Patent Description:
Conventionally, an electrophotographic type image forming apparatus such as a laser printer and an LED printer has been well known in the art. A developing cartridge is used in the image forming apparatus. The developing cartridge includes a developing roller configured to supply developing agent. One conventional image forming apparatus is described in Patent Literature <NUM>, for example. The image forming apparatus according to the Patent Literature <NUM> includes a drawer. The drawer includes a photosensitive drum. The developing cartridge is configured to be attached to the drawer. Upon attachment of the developing cartridge to the drawer, the photosensitive drum and the developing roller contact with each other. A conventional electrophotographic type image forming apparatus is known from <CIT>.

From <CIT> it is known a developing cartridge that includes: a casing; a developing roller; a shaft extending in a first direction; a first inclined surface; a second inclined surface; an elastic member; and a first protrusion. The shaft is movable in the first direction relative to the casing and the developing roller, and is movable in the second direction together with the same. The first inclined surface is positioned at one end portion of the shaft, while the second inclined surface is positioned at another end portion of the shaft. The first and second inclined surfaces are inclined relative to the first direction. The first protrusion is movable in the first direction together with the second inclined surface. The shaft is movable from a first position to a second position when the second inclined surface receives a pressing force directed in a direction from the another end portion to the one end portion.

In the image forming apparatus disclosed in the Patent Literature <NUM>, a separating operation is configured to be performed to temporarily separate the developing cartridge from the photosensitive drum. To perform the separating operation, the developing cartridge includes a shaft, a first cam, a second cam, and a resiliently urging member. The first cam is attached to one end portion of the shaft. The second cam and the resiliently urging member are attached to another end portion of the shaft. The shaft is movable relative to a casing of the developing cartridge.

For manufacturing or recycling the developing cartridge, conceivably, the resiliently urging member is attached to the other end portion of the shaft after the shaft is attached to the casing. However, since the shaft is movable relative to the casing of the developing cartridge, the shaft may be displaced relative to the casing when the resiliently urging member is attached to the other end portion of the shaft. This poses a problem that attaching the resiliently urging member to the other end portion of the shaft may become difficult.

It is an object of the present disclosure to provide a technique that can facilitate attachment of the resiliently urging member to the shaft that is movable relative to the casing.

A first disclosure of the present application is a method of assembling a developing cartridge, the developing cartridge including: a casing configured to accommodate developing agent and having a through-hole extending in a first direction; a shaft extending in the first direction through the through-hole and movable in the first direction relative to the casing; a first cam positioned at one end portion of the shaft in the first direction and movable together with the shaft in the first direction relative to the casing; a second cam positioned at another end portion of the shaft in the first direction and movable together with the shaft in the first direction relative to the casing; and a resiliently urging member attached to the another end portion of the shaft and positioned between the casing and the second cam, the resiliently urging member being configured to expand and compress in the first direction. The method of assembling is characterized by including steps of: (a) attaching the first cam to the one end portion of the shaft; (b) inserting the shaft to which the first cam is attached in the through-hole after the step (a); and (c) after the step (b), attaching the resiliently urging member to the another end portion of the shaft in a state where the first cam is in contact with a jig in the first direction and in a direction from the one end portion toward the another end portion of the shaft.

A second disclosure of the present application is the method of assembling according to the first disclosure, according to which: the first cam has a first hole in which the one end portion of the shaft is to be inserted; and the developing cartridge further includes a first retaining ring attached to the one end portion of the shaft and configured to prevent the first cam from coming off the one end portion of the shaft. The method of assembling is characterized in that the step (a) includes steps of: (a-<NUM>) inserting the one end portion of the shaft in the first hole; and (a-<NUM>), after the step (a-<NUM>), attaching the first retaining ring to the one end portion of the shaft in a state where the first cam and the shaft are held by a holding tool.

A third disclosure of the present application is the method of assembling according to the first or second disclosure, according to which the developing cartridge further includes a second retaining ring attached to the another end portion of the shaft. The method of assembling is characterized by further including a step of: (d) attaching the second retaining ring to the another end portion of the shaft in the state where the first cam is in contact with the jig in the first direction, after the step (c).

A fourth disclosure of the present application is the method of assembling according to the third disclosure, according to which the second retaining ring is positioned between the resiliently urging member and the second cam in the first direction. The method of assembling is characterized by further including a step of: (e) attaching the second cam to the another end portion of the shaft after the step (d).

A fifth disclosure of the present application is the method of assembling according to the fourth disclosure, according to which: the casing has a first outer surface at which the first cam is positioned and a second outer surface at which the second cam is positioned; and the developing cartridge further includes a gear cover fixed to the second outer surface, the gear cover having a stop surface facing the second cam in the first direction. The method of assembling is characterized in that: in the step (e), the second cam is attached to the another end portion of the shaft, and the gear cover is attached to the second outer surface of the casing.

A sixth disclosure of the present application is the method of assembling according to the fifth disclosure, according to which: the developing cartridge further includes: a developing roller extending in the first direction; a first bearing fixed to the first outer surface of the casing and supporting one end portion of the developing roller in the first direction; and a second bearing fixed to the second outer surface of the casing and supporting another end portion of the developing roller in the first direction. The method of assembling is characterized by further including a step of: attaching the first bearing, the second bearing, and the developing roller to the casing after the steps (a) through (d) and before the step (e).

A seventh disclosure of the present application is the method of assembling according to any one of the first through sixth disclosures, according to which: the shaft is movable in the first direction relative to the casing between a first position and a second position; and the first cam is positioned closer to the casing when the shaft is at the first position than when the shaft is at the second position. The method of assembling is characterized in that: in the step (c), the resiliently urging member is attached to the another end portion of the shaft in a state where the shaft is positioned at the first position by the jig.

An eighth disclosure of the present application is the method of assembling according to any one of the first through seventh disclosures, the method of assembling being characterized in that the resiliently urging member is a spring.

According to the first through eighth disclosures of the present application, the shaft can be fixed in position in the first direction by making the jig in contact with the first cam. Hence, the resiliently urging member can be easily attached to the another end portion of the shaft.

Further, according to the second disclosure of the present application, displacement of the first cam and the shaft can be restrained by the holding tool. Hence, the first retaining ring can be easily attached to the shaft.

Further, according to the third disclosure of the present application, the shaft can be fixed in position in the first direction by making the jig in contact with the first cam. Hence, the second retaining ring can be easily attached to the another end portion of the shaft.

Further, according to the fifth disclosure of the present application, the stop surface of the gear cover can prevent the second cam from coming off the another end portion of the shaft.

Further, according to the seventh disclosure of the present application, a protruding length of the another end portion of the shaft protruding from the casing is longer when the shaft is at the first position than when the shaft is at the second position. Accordingly, attachment of the resiliently urging member to the shaft can be performed more easily.

Hereinafter, an embodiment according to the present disclosure will be described with reference to accompanying drawings.

Incidentally, in the following description, an extending direction of a shaft will be referred to as a "first direction". Further, a direction in which one end portion of a casing where a developing roller is positioned and another end portion of the casing are aligned with each other will be referred to as a "second direction". The first direction and the second direction cross each other (preferably, perpendicular to each other).

<FIG> is a conceptual diagram of an image forming apparatus <NUM>. The image forming apparatus <NUM> is an electro-photographic type printer. A laser printer and an LED printer are given as examples of the image forming apparatus <NUM>. As illustrated in <FIG>, the image forming apparatus <NUM> includes a main frame <NUM>, a controller <NUM>, a drum unit <NUM>, and four developing cartridges <NUM>.

<FIG> is a perspective view of the drum unit <NUM> and one developing cartridge <NUM>. As illustrated in <FIG> and <FIG>, the drum unit <NUM> includes a drum frame <NUM> and four photosensitive drums <NUM>. The four developing cartridges <NUM> are attachable to the drum frame <NUM>. That is, the drum unit <NUM> according to the present embodiment is a drawer to which the four developing cartridges <NUM> are attachable. The drum unit <NUM> having the four photosensitive drums <NUM> attached thereto can be attached to the main frame <NUM>.

The four developing cartridges <NUM> respectively accommodate therein developing agent of four different colors (for example, the colors of cyan, magenta, yellow and black). The developing agent is toner, for example. The image forming apparatus <NUM> is configured to form an image on a surface of a printing sheet with the developing agent supplied from the developing cartridges <NUM>. However, the number of the developing cartridges <NUM> to be attached to the drum unit <NUM> may be one through three, or not less than five.

As illustrated in <FIG>, each of the four developing cartridges <NUM> includes a memory <NUM>. The memory <NUM> is a storage medium configured to read and write information. The memory <NUM> is an IC chip, for example. In a case where the drum unit <NUM> to which the four developing cartridges <NUM> are attached is attached to the image forming apparatus <NUM>, the memory <NUM> of each developing cartridge <NUM> is electrically connected to the controller <NUM> of the image forming apparatus <NUM>.

The controller <NUM> includes a processor, such as a CPU. The controller <NUM> is configured to perform a printing process in the image forming apparatus <NUM> in accordance with the operation of the processor based on programs. Further, the controller <NUM> is also configured to read information stored in the memory <NUM> and write information in the memory <NUM>.

<FIG> and <FIG> are perspective views of the developing cartridge <NUM>. <FIG> is an exploded perspective view of the developing cartridge <NUM>. As illustrated in <FIG>, the developing cartridge <NUM> includes a casing <NUM>, a developing roller <NUM>, a gear portion <NUM>, a memory assembly <NUM>, and a separating unit <NUM>.

The casing <NUM> is configured to store developing agent therein. The casing <NUM> has a first outer surface <NUM>, and a second outer surface <NUM>. The first outer surface <NUM> is positioned at one end of the casing <NUM> in the first direction. The second outer surface <NUM> is positioned at another end of the casing <NUM> in the first direction. The first outer surface <NUM> and the second outer surface <NUM> are spaced apart from each other in the first direction. The casing <NUM> extends in the first direction as well as in the second direction between the first outer surface <NUM> and the second outer surface <NUM>.

An accommodation chamber <NUM> is provided inside the casing <NUM>. The developing agent is accommodated in the accommodation chamber <NUM>. Further, the casing <NUM> has an opening <NUM>. The opening <NUM> is positioned at one end portion of the casing <NUM> in the second direction. An interior and an exterior of the casing <NUM> are communicated with each other through the opening <NUM>.

As illustrated in <FIG>, the casing <NUM> includes a cap <NUM> at the first outer surface <NUM>. The cap <NUM> is attached to a supply opening positioned at the first outer surface <NUM> of the casing <NUM>. The cap <NUM> is configured to cover the supply opening. The cap <NUM> is detached from the first outer surface <NUM> to supply developing agent into the casing <NUM>. The developing agent is then supplied into the accommodation chamber <NUM> through the supply opening.

The developing cartridge <NUM> includes an agitator (not illustrated) positioned in the accommodation chamber <NUM> of the casing <NUM>. The agitator includes a fin. An agitator gear <NUM> of the gear portion <NUM> is attached to one end portion of the agitator in the first direction. Specifically, the agitator gear <NUM> is fixed to the one end portion of the agitator in the first direction. As the agitator gear <NUM> rotates, the agitator rotates about an agitator axis extending in the first direction. And, the developing agent in the accommodation chamber <NUM> is agitated by the rotation of the fin.

Further, the casing <NUM> has a first through-hole <NUM>, a groove <NUM>, and a second through-hole <NUM>. The first through-hole <NUM>, the groove <NUM>, and the second through-hole <NUM> are positioned at an outer surface of the casing <NUM>. The first through-hole <NUM> is positioned at one end of the casing <NUM> in the first direction. The first through-hole <NUM> penetrates through a part of the casing <NUM> in the first direction. The second through-hole <NUM> is positioned at another end of the casing <NUM> in the first direction. The second through-hole <NUM> penetrates through a part of the casing <NUM> in the first direction. The groove <NUM> is positioned between the first through-hole <NUM> and the second through-hole <NUM>. The groove <NUM> extends in the first direction at the outer surface of the casing <NUM>.

The developing roller <NUM> is a roller rotatable about a developing axis extending in the first direction. The developing roller <NUM> is positioned at the opening <NUM> of the casing <NUM>. That is, the developing roller <NUM> is positioned at the one end portion of the casing <NUM> in the second direction. The developing roller <NUM> includes a developing-roller body <NUM>, and a developing-roller shaft <NUM>. The developing-roller body <NUM> is a hollow cylindrical member extending in the first direction. The developing-roller body <NUM> is made of, for example, rubber having elasticity. The developing-roller shaft <NUM> is a solid cylindrical member extending in the first direction to penetrate through the developing-roller body <NUM>. The developing-roller body <NUM> is attached to the developing-roller shaft <NUM>. Specifically, the developing-roller body <NUM> is fixed to the developing-roller shaft <NUM>. As a material of the developing-roller shaft <NUM>, metal or electrically conductive resin is employed.

The developing cartridge <NUM> includes a first bearing <NUM>, and a second bearing <NUM>. The first bearing <NUM> is attached to the first outer surface <NUM> of the casing <NUM>. Specifically, the first bearing <NUM> is fixed to the first outer surface <NUM> of the casing <NUM>. The second bearing <NUM> is attached to the second outer surface <NUM> of the casing <NUM>. Specifically, the second bearing <NUM> is fixed to the second outer surface <NUM> of the casing <NUM>. One end portion of the developing-roller shaft <NUM> in the first direction is inserted in the first bearing <NUM>. With this structure, the one end portion of the developing-roller shaft <NUM> in the first direction is supported so as to be rotatable about the developing axis extending in the first direction. Another end portion of the developing-roller shaft <NUM> in the first direction is inserted in the second bearing <NUM>. With this structure, the other end portion of the developing-roller shaft <NUM> in the first direction is supported so as to be rotatable about the developing axis extending in the first direction.

Further, a developing-roller gear <NUM> of the gear portion <NUM> is attached to the other end portion of the developing-roller shaft <NUM> in the first direction. Specifically, the developing-roller gear <NUM> is fixed to the other end portion of the developing roller shaft <NUM> in the first direction. Accordingly, as the developing-roller gear <NUM> rotates, the developing-roller shaft <NUM> rotates to rotate the developing-roller body <NUM> together with the developing-roller shaft <NUM>.

Incidentally, the developing roller shaft <NUM> may not penetrate through the developing-roller body <NUM> in the first direction. For example, the developing-roller shaft <NUM> may extend in the first direction from each end of the developing-roller body <NUM> in the first direction.

Further, the developing cartridge <NUM> includes a supply roller <NUM>. The supply roller <NUM> is positioned between the developing roller <NUM> and the agitator. An outer peripheral surface of the supply roller <NUM> and an outer peripheral surface of the developing roller <NUM> are in contact with each other. The developing agent in the accommodation chamber <NUM> of the casing <NUM> is supplied to the developing roller <NUM> through the supply roller <NUM>. Thereafter, the developing agent on the outer peripheral surface of the developing roller <NUM> is supplied to the photosensitive drum <NUM> of the drum unit <NUM>. At this time, the developing agent is moved from the developing roller <NUM> to the photosensitive drum <NUM> according to an electrostatic latent image formed on an outer peripheral surface of the photosensitive drum <NUM>. As such, the electrostatic latent image becomes a visible image on the outer peripheral surface of the photosensitive drum <NUM>.

The gear portion <NUM> is positioned at the second outer surface <NUM> of the casing <NUM>. The gear portion <NUM> includes a gear cover <NUM>, a coupling <NUM>, and a plurality of gears. The gear cover <NUM> is attached to the second outer surface <NUM> of the casing <NUM>. Specifically, the gear cover <NUM> is fixed to the second outer surface <NUM> of the casing <NUM>. The plurality of gears includes the above-described agitator gear <NUM> and the developing-roller gear <NUM>. At least a part of the plurality of gears is positioned between the second outer surface <NUM> and the gear cover <NUM> in the first direction.

The coupling <NUM> is exposed through the gear cover <NUM>. Upon attachment of the developing cartridge <NUM> attached to the drum unit <NUM> to the image forming apparatus <NUM>, a drive shaft of the image forming apparatus <NUM> is configured to be connected to the coupling <NUM>. Thus, the rotation of the drive shaft is transmitted to the agitator gear <NUM> and the developing-roller gear <NUM> through the coupling <NUM>.

Incidentally, the plurality of gears in the gear portion <NUM> may transmit a rotational force by meshing engagement of gear teeth, or by frictional force. In the latter case, an outer peripheral surface of each gear may be made of rubber.

The gear cover <NUM> has a third through-hole <NUM>, and a stop surface <NUM>. The third through-hole <NUM> is positioned at the other end of the casing <NUM> in the first direction. The third through-hole <NUM> is positioned between the second through-hole <NUM> and a second cam <NUM> (described later) in the first direction. The stop surface <NUM> faces the second outer surface <NUM> of the casing <NUM> in the first direction. Further, the stop surface <NUM> faces a stop protrusion <NUM> (described later) of the second cam <NUM> in the first direction.

The memory assembly <NUM> is positioned at the first outer surface <NUM> of the casing <NUM>. The memory assembly <NUM> includes the memory <NUM> as a storage medium, and a holder <NUM> holding the memory <NUM>. The memory <NUM> is an IC chip, for example. The memory <NUM> is positioned on an outer surface of the holder <NUM>.

The memory <NUM> is configured to store various information about the developing cartridge <NUM>. Specifically, the memory <NUM> stores at least one of: a cumulative number of printed sheets using the developing roller <NUM>; a cumulative rotation number of the developing roller <NUM>; and a cumulative consumption amount of the developing agent. The information is information indicative of a service life of the developing cartridge <NUM>. Further, the memory <NUM> may further store information such as the serial number of the developing cartridge <NUM>, and a matching model therefor. The memory <NUM> has an electrical contact surface. The electrical contact surface is made of metal as a conductor.

As illustrated in <FIG>, the developing cartridge <NUM> includes a holder cover <NUM>. The holder cover <NUM> is attached to the first outer surface <NUM> of the casing <NUM>. Specifically, the holder cover <NUM> is fixed to the first outer surface <NUM> of the casing <NUM>. The holder <NUM> is attached to the holder cover <NUM>. The holder <NUM> is movable in the second direction relative to the casing <NUM> and the holder cover <NUM>.

After the developing cartridges <NUM> attached to the drum unit <NUM> are attached to the image forming apparatus <NUM>, each developing cartridge <NUM> can perform a separating operation relative to the drum unit <NUM> in response to supply of a driving force from the image forming apparatus <NUM> to the developing cartridge <NUM>. The separating operation is an operation to move the developing cartridge <NUM> relative to the drum unit <NUM> from a contacting state where the developing roller <NUM> is in contact with the photosensitive drum <NUM> to a separated state where the developing roller <NUM> is separated away from the photosensitive drum <NUM>. For example, in a case where monochromatic printing is to be performed in the image forming apparatus <NUM>, the developing cartridges <NUM> for the colors of cyan, magenta, and yellow other than black perform the separating operations. However, the developing cartridge <NUM> for the color of black may also perform the separating operation.

The separating unit <NUM> is a mechanism for switching the developing cartridge <NUM> between the contacting state and the separated state. As illustrated in <FIG>, the separating unit <NUM> includes a shaft <NUM>, a first cam <NUM>, a first retaining ring <NUM>, the second cam <NUM>, a second retaining ring <NUM>, and a spring <NUM>.

The shaft <NUM> is positioned at the outer surface of the casing <NUM>. The shaft <NUM> extends along a first axis A1 extending in the first direction. Specifically, the shaft <NUM> extends in the first direction along the groove <NUM> of the casing <NUM>. Further, the shaft <NUM> is inserted in the first through-hole <NUM>, the second through-hole <NUM>, and the third through-hole <NUM>. The shaft <NUM> is, for example, solid cylindrical. However, the shaft <NUM> may have a prismatic columnar shape. The shaft <NUM> has one end portion <NUM>, and another end portion <NUM>. The one end portion <NUM> is positioned at one end of the shaft <NUM> in the first direction. The other end portion <NUM> is positioned at another end portion of the shaft <NUM> in the first direction. The shaft <NUM> is made of, for example, metal such as iron.

The first cam <NUM> is attached to the one end portion <NUM> of the shaft <NUM>. Specifically, the first cam <NUM> has a first hole <NUM>. The first hole <NUM> extends, from a surface of the first cam <NUM> that faces the second cam <NUM>, in a direction away from the second cam <NUM> in the first direction. The one end portion <NUM> of the shaft <NUM> is inserted in the first hole <NUM>. The first cam <NUM> is positioned at the first outer surface <NUM> of the casing <NUM>. As a material of the first cam <NUM>, for example, resin is employed.

The first cam <NUM> has a first sloped surface <NUM>. The first sloped surface <NUM> is positioned at a part of a peripheral surface of the first cam <NUM> centered on the first axis A1. The first sloped surface <NUM> is inclined with respect to the first direction. The first sloped surface <NUM> extends to be separated farther away from the developing roller <NUM> in the second direction as extending away from the second cam <NUM> in the first direction. That is, the first sloped surface <NUM> extends to approach the shaft <NUM> in a radial direction with respect to the first axis A1 as extending away from the other end portion <NUM> of the shaft <NUM> in the first direction.

The first retaining ring <NUM> is a member for preventing the first cam <NUM> from detaching from the one end portion <NUM> of the shaft <NUM>. The first retaining ring <NUM> is a plate-like member having a generally C-shape. The shaft <NUM> has an annular first groove <NUM> (see <FIG>) on an outer peripheral surface of the one end portion <NUM> of the shaft <NUM>. The first retaining ring <NUM> is attached to the first groove <NUM>. In a state where the first cam <NUM> and the first retaining ring <NUM> are attached to the shaft <NUM>, the first retaining ring <NUM> is positioned between one end portion of the first cam <NUM> in the first direction and another end portion of the first cam <NUM> in the first direction. That is, the other end portion of the first cam <NUM> in the first direction is positioned closer to the other end portion <NUM> of the shaft <NUM> than the first retaining ring <NUM> attached to the first groove <NUM> of the shaft <NUM> is to the other end portion <NUM> of the shaft <NUM> in the first direction. The other end portion of the first cam <NUM> and the first retaining ring <NUM> face each other in the first direction. This structure prevents the first cam <NUM> from coming off the one end portion <NUM> of the shaft <NUM> in the first direction.

The second cam <NUM> is attached to the other end portion <NUM> of the shaft <NUM>. Specifically, the second cam <NUM> has a second hole <NUM>. The second hole <NUM> extends, from a surface of the second cam <NUM> that faces the first cam <NUM>, in a direction away from the first cam <NUM> in the first direction. The other end portion <NUM> of the shaft <NUM> is inserted in the second hole <NUM>. The second cam <NUM> is positioned at the second outer surface <NUM> of the casing <NUM>. The second cam <NUM> is positioned closer to the other end portion <NUM> of the shaft <NUM> than the third through-hole <NUM> of the gear cover <NUM> is to the other end portion <NUM> of the shaft <NUM>. As a material of the second cam <NUM>, for example, resin is employed.

The second cam <NUM> has a second sloped surface <NUM>. The second sloped surface <NUM> is positioned at a part of a peripheral surface of the second cam <NUM> centered on the first axis A1. The second sloped surface <NUM> is inclined with respect to the first direction. The second sloped surface <NUM> extends to be separated farther away from the developing roller <NUM> in the second direction as extending toward the first cam <NUM> in the first direction. That is, the second sloped surface <NUM> extends to approach the shaft <NUM> in the radial direction with respect to the first axis A1 as extending toward the one end portion <NUM> of the shaft <NUM>.

As illustrated in <FIG>, the second cam <NUM> has the stop protrusion <NUM>. The stop protrusion <NUM> protrudes from an outer surface of the second cam <NUM> outwardly in a radial direction of the shaft <NUM>. The stop protrusion <NUM> and the stop surface <NUM> of the gear cover <NUM> face each other in the first direction. Further, the stop protrusion <NUM> and the stop surface <NUM> are configured to make contact with each other in the first direction. This configuration prevents the second cam <NUM> from coming off the other end portion <NUM> of the shaft <NUM> in the first direction.

The second retaining ring <NUM> is a member for receiving an urging force of the spring <NUM>. The second retaining ring <NUM> is positioned between the spring <NUM> and the second cam <NUM> in the first direction. The second retaining ring <NUM> is a plate-like member having a generally C-shape. The shaft <NUM> has an annular second groove <NUM> on the outer peripheral surface of the other end portion <NUM> of the shaft <NUM>. The second retaining ring <NUM> is attached to the second groove <NUM>.

The shaft <NUM> is movable, relative to the casing <NUM>, in the first direction between a first position and a second position. The first cam <NUM>, the first retaining ring <NUM>, the second cam <NUM>, and the second retaining ring <NUM> are movable together with the shaft <NUM> in the first direction relative to the casing <NUM>. The first cam <NUM> is positioned closer to the casing <NUM> in the first direction in a case where the shaft <NUM> is at the first position than in a case where the shaft <NUM> is at the second position. The second cam <NUM> is positioned farther from the casing <NUM> in the first direction in the case where the shaft <NUM> is at the first position than in the case where the shaft <NUM> is at the second position. That is, the movement from the first position to the second position is a movement in a direction from the second cam <NUM> toward the first cam <NUM>. The movement from the second position to the first position is a movement in a direction from the first cam <NUM> toward the second cam <NUM>.

The spring <NUM> is a resiliently urging member configured to extend and compress in the first direction. The spring <NUM> is attached to the other end portion <NUM> of the shaft <NUM>. The spring <NUM> is positioned between the second outer surface <NUM> of the casing <NUM> and the second cam <NUM> in the first direction. Specifically, the spring <NUM> is positioned between the second outer surface <NUM> of the casing <NUM> and the third through-hole <NUM> of the gear cover <NUM> in the first direction. One end of the spring <NUM> in the first direction is in contact with the second outer surface <NUM> of the casing <NUM>. Another end of the spring <NUM> in the first direction is in contact with the second retaining ring <NUM>. The spring <NUM> according to the present embodiment is a coil spring in a spiral shape. The other end portion <NUM> of the shaft <NUM> is inserted in an interior of the spring <NUM>.

The spring <NUM> is configured to expand and compress in the first direction between a first state and a second state. The spring <NUM> is in the first state in the case where the shaft <NUM> is at the first position. The spring <NUM> is in the second state in the case where the shaft <NUM> is at the second position. A length of the spring <NUM> in the first direction is longer in the first state than in the second state. Further, the spring <NUM> is compressed to be shorter than a natural length of the spring <NUM> in a state where the gear cover <NUM> and the shaft <NUM> are attached to the casing <NUM>, and the second cam <NUM>, the second retaining ring <NUM>, and the spring <NUM> are attached to the shaft <NUM>. Hence, the shaft <NUM> is urged toward the first position from the first position by a repulsive force of the spring <NUM>.

For performing the separating operation, a lever (not illustrated) is configured to protrude, from the main frame <NUM>, toward the second cam <NUM> of the developing cartridge <NUM> in the image forming apparatus <NUM>. Hence, the second cam <NUM> is pushed by the lever. The second cam <NUM> is pressed in a direction from the second cam <NUM> toward the first cam <NUM> in the first direction. Accordingly, the spring <NUM> is compressed from the first state to the second state, and the shaft <NUM> is moved from the first position to the second position.

At this time, the first sloped surface <NUM> of the first cam <NUM> moves in the first direction while making contact with a part of the drum frame <NUM>. Hence, the first cam <NUM> moves in the second direction, relative to the drum frame <NUM>, in a direction away from the photosensitive drum <NUM>. Similarly, the second sloped surface <NUM> of the second cam <NUM> moves in the first direction while making contact with another part of the drum frame <NUM>. Hence, the second cam <NUM> moves in the second direction, relative to the drum frame <NUM>, in the direction away from the photosensitive drum <NUM>.

The casing <NUM> and the developing roller <NUM> move in the second direction, relative to the drum frame <NUM>, together with the shaft <NUM>, the first cam <NUM>, and the second cam <NUM>, in the direction away from the photosensitive drum <NUM>. As a result, the position of the developing cartridge <NUM> is switched from the contacting position where the developing roller <NUM> is in contact with the photosensitive drum <NUM> to the separated position where the developing roller <NUM> is separated away from the photosensitive drum <NUM>.

Next, procedures for assembling the developing cartridge <NUM> will be described. The developing cartridge <NUM> is assembled when the developing cartridge <NUM> is manufactured or recycled. Recycling of the developing cartridge <NUM> is a work to render the developing cartridge <NUM> back into a reusable state through an inspection of the used developing cartridge <NUM>, replacement of parts and components of the developing cartridge <NUM> as needed, and refilling developing agent in the accommodation chamber <NUM> of the developing cartridge <NUM>. <FIG> is a flowchart illustrating a recycling procedure as one example of assembling of the developing cartridge <NUM>.

For performing recycling as one example of assembling of the developing cartridge <NUM>, an operator first detaches the holder cover <NUM> and the memory assembly <NUM> from the casing <NUM> (step S1). Then, the operator removes the memory <NUM> from the holder <NUM>, and attaches a new memory <NUM> to the holder <NUM>. Next, the operator detaches the cap <NUM> from the first outer surface <NUM> of the casing <NUM> (step S2). Then, the operator sucks out the toner remaining in the accommodation chamber <NUM> of the casing <NUM> through the supply opening (step S3).

Next, the operator detaches the gear cover <NUM> from the second outer surface <NUM> of the casing <NUM>. Specifically, the operator detaches, from the casing <NUM> and the gear cover <NUM>, bolts fixing the gear cover <NUM> to the second outer surface <NUM> of the casing <NUM>. Further, concurrently with the detachment of the gear cover <NUM> from the second outer surface <NUM> of the casing <NUM>, the operator detaches the second cam <NUM> from the other end portion <NUM> of the shaft <NUM>, and takes the other end portion <NUM> of the shaft <NUM> out of the third through-hole <NUM> (step S4). Further, the operator detaches the plurality of gears of the gear portion <NUM> from the second outer surface <NUM> of the casing <NUM> (step S5).

Subsequently, the operator determines whether the first cam <NUM> needs to be replaced or not (step S6). In a case where the operator determines that replacement of the first cam <NUM> is necessary (step S6: YES), the operator performs a work to replace the first cam <NUM> (step S7).

<FIG> is a flowchart illustrating procedures to perform the replacement work on the first cam <NUM>. As illustrated in <FIG>, for exchanging the first cam <NUM>, the operator first detaches, from the casing <NUM>, the shaft <NUM> to which the first cam <NUM> is attached (step S71). Specifically, the operator moves the shaft <NUM> to which the first cam <NUM> is attached in the direction from the other end portion <NUM> toward the one end portion <NUM> of the shaft <NUM>. In this way, the operator pulls out the shaft <NUM> from the second through-hole <NUM>, the groove <NUM>, and the first through-hole <NUM> of the casing <NUM>.

Subsequently, the operator detaches the first retaining ring <NUM> from the one end portion <NUM> of the shaft <NUM>. Then, the operator pulls out the one end portion <NUM> of the shaft <NUM> from the first hole <NUM> of the first cam <NUM>. Thus, the operator detaches the used first cam <NUM> from the shaft <NUM> (step S72).

Thereafter, the operator prepares a new first cam <NUM>. The operator then sets the new first cam <NUM> to be held in a holding tool <NUM> (step S73). <FIG> is a view illustrating a state where the first cam <NUM> is held by the holding tool <NUM>. As illustrated in <FIG>, the holding tool <NUM> has a first recessed portion <NUM> configured to hold the first cam <NUM>. The operator inserts the first cam <NUM> in the first recessed portion <NUM>. The outer surface of the first cam <NUM> comes into contact with an inner surface of the holding tool <NUM>. This structure restrains displacement of the first cam <NUM> relative to the holding tool <NUM>.

In this state, the operator inserts the one end portion <NUM> of the shaft <NUM> in the first hole <NUM> of the first cam <NUM> (step S74). At this time, the holding tool <NUM> restrains displacement of the first cam <NUM>. Accordingly, the one end portion <NUM> of the shaft <NUM> can be easily inserted in the first hole <NUM> of the first cam <NUM>.

As illustrated in <FIG>, the first cam <NUM> has a slit <NUM>. The slit <NUM> is a through-hole extending outwardly in the radial direction of the shaft <NUM> from the first hole <NUM> of the first cam <NUM>. After the step S74, the operator attaches the first retaining ring <NUM> to the first groove <NUM> of the one end portion <NUM> of the shaft <NUM> through the slit <NUM> in a state where the first cam <NUM> and the shaft <NUM> are held by the holding tool <NUM> (step S75).

<FIG> is a view illustrating a state where the step S75 is complete. In the step S75, displacement of the first cam <NUM> and the shaft <NUM> are restrained by the holding tool <NUM>. Hence, the one end portion <NUM> of the shaft <NUM> is restrained from coming off the first hole <NUM> of the first cam <NUM>. Accordingly, the operator can easily attach the first retaining ring <NUM> to the first groove <NUM> of the shaft <NUM>.

Thereafter, the operator inserts the shaft <NUM> to which the first cam <NUM> has been attached into the first through-hole <NUM>, the groove <NUM>, and the second through-hole <NUM> of the casing <NUM> (step S76). Hence, the shaft <NUM> to which the first cam has been attached is attached to the casing <NUM>.

Subsequently, the operator sets the casing <NUM> to be held by a jig <NUM> (step S77). <FIG> and <FIG> are views illustrating a state where the casing <NUM> is held by the jig <NUM>. As illustrated in <FIG> and <FIG>, the jig <NUM> has a second recessed portion <NUM> configured to hold the casing <NUM>, and a third recessed portion <NUM> configured to hold the other end portion <NUM> of the shaft <NUM>. The operator inserts the casing <NUM> in the second recessed portion <NUM>, and inserts the other end portion <NUM> of the shaft <NUM> in the third recessed portion <NUM>. Hence, displacement of the casing <NUM> and the shaft <NUM> relative to the jig <NUM> is restrained. Further, the first cam <NUM> is in contact with an inner surface <NUM> of the second recessed portion <NUM> of the jig <NUM>.

In this state, the operator slightly lifts up the other end portion <NUM> of the shaft <NUM> from the third recessed portion <NUM>, and attaches the spring <NUM> to the other end portion <NUM> of the shaft <NUM> (step S78).

At this time, the inner surface <NUM> of the jig <NUM> contacts the first cam <NUM> in the first direction. Specifically, the inner surface <NUM> of the jig <NUM> contacts the first cam <NUM> in a direction toward the other end portion <NUM> from the one end portion <NUM> of the shaft <NUM>. Hence, the position of the shaft <NUM> is fixed at the first position. Displacement of the shaft <NUM> from the first position to the second position is prevented by the inner surface <NUM> of the jig <NUM>. Accordingly, the operator can easily attach the spring <NUM> to the other end portion <NUM> of the shaft <NUM>.

Further, a protruding length of the shaft <NUM> protruding in the first direction from the second outer surface <NUM> of the casing <NUM> is greater when the shaft <NUM> is at the first position than when the shaft <NUM> is at the second position. Accordingly, the operator can attach the spring <NUM> to the other end portion <NUM> of the shaft <NUM> more easily.

Subsequently, the operator attaches the second retaining ring <NUM> to the other end portion <NUM> of the shaft <NUM> in the state where the casing <NUM> is held by the jig <NUM> (step S79). Specifically, the operator attaches the second retaining ring <NUM> to the second groove <NUM> of the shaft <NUM> while the other end portion <NUM> of the shaft <NUM> is inserted in the second recessed portion <NUM> of the jig <NUM>.

At this time, the inner surface <NUM> of the jig <NUM> contacts the first cam <NUM> in the first direction. Specifically, the inner surface <NUM> of the jig <NUM> contacts the first cam <NUM> in a direction toward the other end portion <NUM> of the shaft <NUM> from the one end portion <NUM> of the shaft <NUM>. Hence, the position of the shaft <NUM> is fixed at the first position. Displacement of the shaft <NUM> from the first position to the second position is prevented by the inner surface <NUM> of the jig <NUM>. Accordingly, the operator can easily attach the second retaining ring <NUM> to the other end portion <NUM> of the shaft <NUM>.

Further, the protruding length of the shaft <NUM> protruding in the first direction from the second outer surface <NUM> of the casing <NUM> is greater when the shaft <NUM> is at the first position than when the shaft <NUM> is at the second position. Accordingly, the operator can attach the second retaining ring <NUM> to the other end portion <NUM> of the shaft <NUM> more easily.

Turning back to <FIG>, in a case where the operator determines that exchange of the first cam <NUM> is unnecessary in the step S6 (step S6: No), or in a case where the replacement work in the step S7 is finished, then, the operator determines whether replacement of the developing roller <NUM> is necessary (step S8). In a case where the replacement of the developing roller <NUM> is determined to be necessary (step S8: Yes), the operator performs an exchanging work for the developing roller <NUM> (step S9).

<FIG> is a flowchart illustrating procedures to replace the developing roller <NUM>. As illustrated in <FIG>, for performing the replacement of the developing roller <NUM>, the operator first detaches the first bearing <NUM> and the second bearing <NUM> from the casing <NUM> (step S91). Specifically, the operator detaches the first bearing <NUM> from the first outer surface <NUM> of the casing <NUM>, and pulls the one end portion in the first direction of the developing roller shaft <NUM> out of the first bearing <NUM>. Further, the operator detaches the second bearing <NUM> from the second outer surface <NUM> of the casing <NUM>, and pulls the other end portion in the first direction of the developing roller shaft <NUM> out of the second bearing <NUM>.

Next, the operator replaces the used developing roller <NUM> with a new developing roller <NUM> (step S92). Specifically, the operator removes the used developing roller <NUM> through the opening <NUM> of the casing <NUM>, and attaches a new developing roller <NUM> at the opening <NUM> of the casing <NUM>.

Thereafter, the operator attaches the first bearing <NUM> and the second bearing <NUM> to the casing <NUM> (step S93). Specifically, the operator inserts the one end portion in the first direction of the developing roller shaft <NUM> into the first bearing <NUM>, and attaches the first bearing <NUM> to the first outer surface <NUM> of the casing <NUM>. More specifically, the operator inserts the one end portion in the first direction of the developing roller shaft <NUM> into the first bearing <NUM>, and fixes the first bearing <NUM> to the first outer surface <NUM> of the casing <NUM>. Further, the operator inserts the other end portion in the first direction of the developing roller shaft <NUM> into the second bearing <NUM>, and attaches the second bearing <NUM> to the second outer surface <NUM> of the casing <NUM>. More specifically, the operator inserts the other end portion in the first direction of the developing roller shaft <NUM> into the second bearing <NUM>, and fixes the second bearing <NUM> to the second outer surface <NUM> of the casing <NUM>.

Turning back to <FIG>, in a case where the operator determines that replacement of the developing roller <NUM> is unnecessary (step S8: No) or in a case where the work in the step S9 is finished, then, the operator attaches the plurality of gears of the gear portion <NUM> to the second outer surface <NUM> of the casing <NUM> (step S10).

Subsequently, the operator attaches the second cam <NUM> to the other end portion <NUM> of the shaft <NUM>, and attaches the gear cover <NUM> to the second outer surface <NUM> of the casing <NUM> (step S11). Specifically, the operator inserts the other end portion <NUM> of the shaft <NUM> attached to the casing <NUM> into the third through-hole <NUM> of the gear cover <NUM>. Thereafter, the operator inserts the other end portion <NUM> of the shaft <NUM> into the second hole <NUM> of the second cam <NUM>. The operator then arranges the stop protrusion <NUM> of the second cam <NUM> to face the stop surface <NUM> of the gear cover <NUM> in the first direction. Thereafter, the operator fixes the gear cover <NUM> to the second outer surface <NUM> of the casing <NUM> with the bolts.

In the step S11, the operator may attach the second cam <NUM> that has been detached in the step S4 to the shaft <NUM>. Further, in a case where the operator determines that replacement of the second cam <NUM> is necessary, the operator may dispose of the second cam <NUM> detached from the shaft <NUM> in the step S4 and attach a new second cam <NUM> to the shaft <NUM> in the step S11.

Thereafter, the operator supplies new developing agent into the accommodation chamber <NUM> of the casing <NUM> through the supply opening of the casing <NUM> (step S12). The operator attaches the cap <NUM> to the supply opening of the casing <NUM> upon completion of filling of the accommodation chamber <NUM> with the developing agent. Thereafter, the operator attaches the holder cover <NUM> and the memory assembly <NUM> to the first outer surface <NUM> of the casing <NUM> (step S14).

While one embodiment according to the present disclosure has been described, the present disclosure is not limited to the above-described embodiment.

The operator may replace the shaft <NUM> in performing the assembling of the developing cartridge <NUM>. Specifically, the operator may replace the shaft <NUM> at the time of recycling of the developing cartridge <NUM>. In a case where replacement of the shaft <NUM> is determined to be necessary, the operator may dispose of the shaft <NUM> detached from the first cam <NUM> in the step S72 and may attach a new shaft <NUM> to the first cam <NUM> in the step S74.

Further, the operator may replace a gear of the gear portion <NUM> with a new gear in performing the assembling of the developing cartridge <NUM>. Specifically, the operator may replace the gear of the gear portion <NUM> at the time of recycling of the developing cartridge <NUM>. In a case where the operator determines that replacement of the gear is necessary, the operator may dispose of the gear detached from the second outer surface <NUM> of the casing <NUM> in the step S5, and may attach a new gear to the second outer surface <NUM> of the casing <NUM> in the step S10.

Further, recycling of the developing cartridge <NUM> has been described in the above-described embodiment. The recycling the developing cartridge <NUM> includes a method of: disassembling partial components of the developing cartridge <NUM>; and reassembling the developing cartridge <NUM>. However, in a manufacturing process of the developing cartridge <NUM>, the developing cartridge <NUM> may be assembled by the same method as the assembling work included in the above-described recycling.

Further, in the above-described embodiment, the coil spring is used as the resiliently urging member. However, instead of the coil spring, other types of springs such as a leaf spring and a torsion spring may be used. Further, instead of the spring, other kinds of urging member such as rubber and sponge may be used.

Further, in the above-described embodiment, the drum unit <NUM> is a drawer to which the four developing cartridges <NUM> are attachable. However, the drum unit may be a drum cartridge to which a single developing cartridge <NUM> is attachable.

Claim 1:
A method of assembling a developing cartridge (<NUM>), the developing cartridge including:
a casing (<NUM>) configured to accommodate developing agent and having a through-hole (<NUM>, <NUM>) extending in a first direction;
a shaft (<NUM>) extending in the first direction through the through-hole (<NUM>, <NUM>) and movable in the first direction relative to the casing (<NUM>);
a first cam (<NUM>) positioned at one end portion (<NUM>) of the shaft (<NUM>) in the first direction, the first cam (<NUM>) being movable together with the shaft (<NUM>) in the first direction relative to the casing (<NUM>);
a second cam (<NUM>) positioned at another end portion (<NUM>) of the shaft (<NUM>) in the first direction, the second cam (<NUM>) being movable together with the shaft (<NUM>) in the first direction relative to the casing (<NUM>); and
a resiliently urging member (<NUM>) attached to the another end portion (<NUM>) of the shaft (<NUM>) and positioned between the casing (<NUM>) and the second cam (<NUM>), the resiliently urging member (<NUM>) being configured to expand and compress in the first direction,
the method comprising steps of:
(a) attaching the first cam (<NUM>) to the one end portion (<NUM>) of the shaft (<NUM>);
(b) inserting the shaft (<NUM>) to which the first cam (<NUM>) is attached in the through-hole (<NUM>, <NUM>) after the step (a); and
(c) after the step (b), attaching the resiliently urging member (<NUM>) to the another end portion (<NUM>) of the shaft (<NUM>) in a state where the first cam (<NUM>) is in contact with a jig (<NUM>) in a direction from the one end portion (<NUM>) toward the another end portion (<NUM>) of the shaft (<NUM>) in the first direction.