Patent Description:
<CIT> discloses a configuration of an image forming apparatus in which a rotational force is transmitted from the apparatus main body of the image forming apparatus to a coupling member on a photosensitive drum, and the rotational force is transmitted to a unit including a developing roller via the developing roller. <CIT> discloses a configuration in which a rotational force is transmitted from an apparatus main body to each of a photosensitive drum and a developing roller. <CIT> discloses a configuration in which a rotational force is transmitted from an apparatus main body to each of a photosensitive drum and a developing roller and a unit including the developing roller is movable such that the developing roller is separated from the photosensitive drum.

In the configuration of the '<NUM> publication, while the developing roller is separated from the photosensitive drum (photosensitive member), the driving force that drives the photosensitive member is not transmitted to the unit including the developing roller. The present invention transmits a driving force that drives a photosensitive member to a developing unit including a developing roller with the developing roller separated from the photosensitive member.

The present invention in its one aspect provides a process unit as specified in claims <NUM> to <NUM>.

The present invention in its one aspect provides an image forming apparatus as specified in claims <NUM> and <NUM>.

According to the present invention, a driving force that drives a photosensitive member can be transmitted to a developing unit including a developing roller with the developing roller separated from the photosensitive member.

Referring to the drawings, exemplary embodiments for carrying out the present invention are now described.

Referring to the drawings, embodiments of an electrophotographic image forming apparatus (hereinafter referred to as an image forming apparatus) and a process unit according to the present invention are now described in detail. The image forming apparatus forms an image on a sheet-shaped recording medium, such as paper, through an electrophotographic image forming process. Examples of the image forming apparatus include an electrophotographic copier, an electrophotographic printer (e.g., a laser beam printer, an LED printer), a facsimile machine, and a word processor. The process unit includes an electrophotographic photosensitive drum (hereinafter referred to as a photosensitive drum), which serves as an image bearing member, and a process means, which acts on the photosensitive drum. The process means may be a developer carrying member (hereinafter referred to as a developing roller). In this embodiment, a process unit attached to the apparatus main body of the image forming apparatus in a detachable manner is referred to as a process cartridge. However, the present invention is also applicable to a process unit that is not detachable from the apparatus main body of the image forming apparatus.

In the following description, unless otherwise specified, the installation surface of the image forming apparatus is a horizontal plane, terms such as "above", "upper", and "upper part" refer to upward in the direction of gravity, and terms such as "below", "lower" and "lower part" refer to downward in the direction of gravity. In addition, unless otherwise specified, terms that describe geometric shapes and relationships, such as straight line, circle, parallel, and perpendicular, encompass shapes and relationships that deviate from the shapes and relationships that are associated with the terms and mathematically precise, due to manufacturing tolerances or the like. Additionally, an XYZ coordinate system is defined in which an X direction is the transport direction of the recording medium in the image forming apparatus projected onto a horizontal plane, a Y direction is the direction parallel to the rotation axis of the photosensitive drum of the image forming apparatus, and a Z direction is upward in the direction of gravity. As for positive and negative directions, a +X direction is the direction from the back of the image forming apparatus to the front (the surface where an operation portion and a paper feed tray are located), the +Y direction is the direction from left to right when the image forming apparatus is viewed from the front, and a +Z direction is a vertically upward direction.

<FIG> is a schematic cross-sectional view showing the configuration of an image forming apparatus <NUM> according to the first embodiment. <FIG> is a perspective view of the image forming apparatus <NUM>. The image forming apparatus <NUM> includes an apparatus main body <NUM> and a toner pack <NUM> (toner container, toner cartridge), which is attachable to the apparatus main body <NUM>. <FIG> is a perspective view of the apparatus main body <NUM> without the toner pack <NUM> attached. The toner pack <NUM> is attached to an attachment portion <NUM> of the apparatus main body <NUM> shown in <FIG> and contains toner for replenishing the apparatus main body <NUM>. The toner pack <NUM> is moved in an attachment direction M shown in <FIG> to be attached. <FIG> is a schematic cross-sectional view of a process cartridge <NUM> placed in the apparatus main body <NUM>.

The image forming apparatus <NUM> is a monochrome printer, which forms an image on a recording material P based on image information input from an external device. The recording material P may be various sheets of different materials, including paper such as plain paper and thick paper, plastic film such as overhead projector sheets, sheets of special shapes such as envelopes and index paper, and cloth.

The apparatus main body <NUM> of the image forming apparatus <NUM> includes an image forming portion <NUM> for forming a toner image on the recording material P, a pickup roller <NUM> for feeding the recording material P to the image forming portion <NUM>, and a fixing portion <NUM> for fixing the toner image formed by the image forming portion <NUM> on the recording material P, and a pair of discharge rollers <NUM>.

The image forming portion <NUM> includes a scanner unit <NUM>, a process cartridge <NUM>, and a transfer roller <NUM> for transferring a toner image, which is a developer image formed on a photosensitive drum <NUM> of the process cartridge <NUM>, onto the recording material P.

As shown in <FIG>, the process cartridge <NUM>, which is detachable from the apparatus main body <NUM> of the image forming apparatus <NUM>, includes a drum unit <NUM> and a developing unit <NUM>. The drum unit <NUM> is a photosensitive member unit having the photosensitive drum <NUM>, which is a photosensitive member on which an electrostatic latent image is formed based on image information. The drum unit <NUM> includes the photosensitive drum <NUM>, a charging roller <NUM>, a pre-exposure portion <NUM>, and a brush unit <NUM>. The developing unit <NUM> has a developing roller <NUM> that develops the electrostatic latent image with toner as a developer.

The photosensitive drum <NUM> is a cylindrical photosensitive member. The photosensitive drum <NUM> has a drum-shaped substrate made of aluminum and a photosensitive layer formed of a negatively charged organic photosensitive member on the substrate. A motor drives and rotates the photosensitive drum <NUM> at a predetermined process speed in a predetermined rotational direction (the direction of arrow Q in <FIG>).

The charging roller <NUM> as a charging member is rotatably in contact with the photosensitive drum <NUM> and forms a charging portion. When a predetermined charging voltage is applied to the charging roller <NUM> by a charging high-voltage power supply, the surface of the photosensitive drum <NUM> is uniformly charged to a predetermined potential. The photosensitive drum <NUM> is negatively charged by the charging roller <NUM>. The pre-exposure portion <NUM> eliminates the surface potential of the photosensitive drum <NUM> before the photosensitive drum <NUM> reaches the charging portion to achieve stable electric discharge in the charging portion. The brush unit <NUM> has a brush portion 24a, which is formed of piled fabric and in contact with the photosensitive drum <NUM> to collect paper dust and the like generated by the recording material P.

The scanner unit <NUM> as an exposure means scans and exposes the surface of the photosensitive drum <NUM> by irradiating, using a polygon mirror, the photosensitive drum <NUM> with laser light corresponding to image information input from an external device. This exposure forms an electrostatic latent image on the surface of the photosensitive drum <NUM> corresponding to the image information. The scanner unit <NUM> is not limited to a laser scanner apparatus and may be an LED exposure apparatus having an LED array including a plurality of LEDs arranged in the longitudinal direction (rotation axis direction, Y direction) of the photosensitive drum <NUM>.

The developing unit <NUM> includes the developing roller <NUM>, serving as a developer carrying member that carries a developer, a developing container <NUM> (developing frame), serving as a frame of the developing unit <NUM>, and a supply roller <NUM> capable of supplying the developing roller <NUM> with the developer. The developing container <NUM> rotatably supports the developing roller <NUM> and the supply roller <NUM>. The developing roller <NUM> has a core bar 31a made of a metal material and a rubber portion 31b. The supply roller <NUM> has a core bar 33a made of a metal material and an elastic portion 33b. A developing blade <NUM>, which is located at the opening of the developing container <NUM> where the developing roller <NUM> is placed, regulates the amount of toner carried by the developing roller <NUM>.

The developing roller <NUM> is arranged at the opening of the developing container <NUM> so as to face the photosensitive drum <NUM>. The supply roller <NUM> is in contact with the developing roller <NUM>, and the supply roller <NUM> supplies the toner, which is the developer contained in the developing container <NUM>, onto the surface of the developing roller <NUM>. The supply roller <NUM> is not necessarily required provided that the toner can be appropriately supplied to the developing roller <NUM>. As the developing roller <NUM> rotates, the toner supplied to the surface of the developing roller <NUM> passes through the portion facing the developing blade <NUM>. The toner is thus shaped into a uniform thin layer and also negatively charged by frictional electrification.

The developing unit <NUM> uses a contact developing method and a reversal developing method as developing methods. In the contact developing method, the toner layer carried on the developing roller <NUM> comes into contact with the photosensitive drum <NUM> in a developing portion (developing region), in which the photosensitive drum <NUM> and the developing roller <NUM> face each other. The developing high-voltage power supply applies a developing voltage to the developing roller <NUM>. Under the developing voltage, the toner carried by the developing roller <NUM> is transferred from the developing roller <NUM> to the surface of the photosensitive drum <NUM> according to the potential distribution on the surface of the photosensitive drum <NUM>, thereby developing the electrostatic latent image into a toner image. In the reversal developing method, a toner image is formed by the toner adhering to the region of the surface of the photosensitive drum <NUM> that has been charged in a charging process and then exposed in an exposure process to reduce the amount of charge.

The developer is a non-magnetic single-component developer that is polymerized toner produced by a polymerization method, has an average particle size of <NUM>, normally has a negative charging polarity, does not contain a magnetic component, and is carried by the developing roller <NUM> mainly through an intermolecular force and an electrostatic force (image force). A single-component developer containing a magnetic component may also be used. Furthermore, in addition to the toner particle, the single-component developer may contain additives (for example, wax or fine silica particles) for adjusting the fluidity and charging performance of the toner. Alternatively, a two-component developer composed of non-magnetic toner and a magnetic carrier may be used as the developer. When a magnetic developer is used, the developer carrying member may be a columnar developing sleeve having a magnet therein.

The developing container <NUM> has a toner containing chamber <NUM> for containing toner. A stirring member <NUM> (toner transporting member) is provided in the toner containing chamber <NUM>. The stirring member <NUM> is rotatably supported in the toner containing chamber <NUM>, stirs the toner in the developing container <NUM>, and transports the toner toward the developing roller <NUM> and the supply roller <NUM>. The stirring member <NUM> also functions to circulate the toner that is unused for development and removed from the developing roller <NUM> in the developing container <NUM> so that the toner in the developing container <NUM> becomes uniform. The stirring member <NUM> is not limited to a rotational member. For example, a stirring member that swings may be used.

The developing container <NUM> also has a toner receiving portion 32a having an interior in communication with the toner containing chamber <NUM>.

An image forming operation of the apparatus main body <NUM> is now described. When an image forming command is input to the apparatus main body <NUM>, the image forming portion <NUM> starts an image forming process based on image information input from an external computer connected to the apparatus main body <NUM>. The scanner unit <NUM> irradiates the photosensitive drum <NUM> with laser light based on the input image information. At this time, the photosensitive drum <NUM> has already been charged by the charging roller <NUM>, and the laser light irradiation forms an electrostatic latent image on the photosensitive drum <NUM>. Then, the developing roller <NUM> develops this electrostatic latent image to form a toner image on the photosensitive drum <NUM>.

In parallel with the image forming process described above, the recording material P is sent out by the pickup roller <NUM> and transported toward the transfer nip formed by the transfer roller <NUM> and the photosensitive drum <NUM>.

A transfer high-voltage power supply applies a transfer voltage to the transfer roller <NUM>, thereby transferring the toner image carried by the photosensitive drum <NUM> to the recording material P. While the recording material P having the toner image transferred thereon passes through the fixing portion <NUM>, the toner image is heated and pressurized. This melts and then hardens the toner particle, thereby fixing the toner image on the recording material P. After passing through the fixing portion <NUM>, the recording material P is discharged to the outside of the apparatus main body <NUM> (outside of the apparatus) by the pair of discharge rollers <NUM> as a discharging means and loaded onto a discharge tray <NUM> as a loading portion formed in the upper part of the apparatus main body <NUM>. The toner that has not been transferred to the recording material P and thus remains on the photosensitive drum <NUM> is charged by the charging roller <NUM> and collected by the developing roller <NUM>. The collected toner is reused to perform another image forming process. A configuration that collects the toner remaining on the photosensitive drum <NUM> with the developing roller <NUM> as described above requires a smaller force to rotate the photosensitive drum <NUM> as compared with a configuration that collects the toner remaining on the photosensitive drum <NUM> with what is referred to as a cleaning blade or the like.

The apparatus main body <NUM> includes a top cover <NUM> in its upper part, and the discharge tray <NUM> is formed on the upper surface of the top cover <NUM>. As shown in <FIG> and <FIG>, the top cover <NUM> includes an opening and closing member <NUM>, which is supported to be openable and closable about a rotation axis 83a extending in the front-rear direction (X direction). The discharge tray <NUM> of the top cover <NUM> has an opening portion 82a opening upward. As shown in <FIG>, the attachment portion <NUM>, to which the toner pack <NUM> is attached, is exposed from the opening portion 82a. The opening portion 82a allows for access to the attached process cartridge <NUM> from the outside of the apparatus main body <NUM>.

The opening and closing member <NUM> is configured to be movable between a closed position covering the attachment portion <NUM> so that the toner pack <NUM> cannot be attached to the apparatus main body <NUM>, and an open position exposing the attachment portion <NUM> so that the toner pack <NUM> can be attached to the apparatus main body <NUM>. The opening and closing member <NUM> is an opening and closing door that opens and closes the opening portion 82a. In the closed position, the opening and closing member <NUM> serves as a part of the discharge tray <NUM>. The opening and closing member <NUM> and the opening portion 82a are formed in the left side of the discharge tray <NUM> as viewed from the front side of the apparatus main body <NUM> (in the -X direction). The front side of the apparatus main body <NUM> described here is the surface on the upstream side of the apparatus main body <NUM> in the direction in which the recording material P is sent out by the pickup roller <NUM> (-X direction). The user inserts a finger into a groove 82b formed in the top cover <NUM>, catches the opening and closing member <NUM> with the finger, and moves the opening and closing member <NUM> to the left (counterclockwise as viewed from the front side) to open the opening and closing member <NUM>.

The opening portion 82a of the discharge tray <NUM> opens so that the attachment portion <NUM> formed in the upper part of the apparatus main body <NUM> is exposed, and the user can access the attachment portion <NUM> by opening the opening and closing member <NUM>. With the developing unit <NUM> attached to the apparatus main body <NUM> and the toner pack <NUM> attached to the attachment portion <NUM>, the user can replenish the developing unit <NUM> with toner from the toner pack <NUM>. This toner replenishing method is referred to as a direct replenishing method. While the toner pack <NUM> is attached to the attachment portion <NUM> of the apparatus main body <NUM>, at least a part of the toner pack <NUM> is exposed to the outside of the apparatus main body <NUM>.

In the direct replenishing method, when the amount of toner remaining in the process cartridge <NUM> becomes low, the process cartridge <NUM> does not need to be removed from the apparatus main body <NUM> or replaced with a new process cartridge. This improves the usability. Also, as compared with a configuration that replaces the entire process cartridge <NUM>, the developing container <NUM> is replenished with toner at a lower cost. Furthermore, as compared even with a configuration that replaces only the developing unit <NUM> of the process cartridge <NUM>, the direct replenishing method is more cost-effective because components such as various rollers and gears do not have to be replaced.

Referring to <FIG> and <FIG>, the configuration of the drum unit <NUM> is now described. <FIG> is an exploded perspective view of the drum unit <NUM>. As shown in <FIG>, the drum unit <NUM> includes the photosensitive drum <NUM>, the charging roller <NUM>, a drum frame <NUM>, a drive-side cover member <NUM>, and a non-drive-side cover member <NUM>.

A drum driving member (drive receiving portion) <NUM> located at one end (drive side, +Y direction end) of the photosensitive drum <NUM> in the longitudinal direction (rotation axis direction, Y direction) receives a rotational force (driving force) from the apparatus main body <NUM> and rotates the photosensitive drum <NUM>. The drum driving member <NUM> is an input means for inputting a rotational driving force received from a power source, such as a motor of the apparatus main body <NUM>, to the photosensitive drum <NUM>. The drum driving member <NUM> has a coupling portion 29a and a gear portion 29b located around the coupling portion 29a.

The photosensitive drum <NUM> is rotatably supported by the drive-side cover member <NUM> and the non-drive-side cover member <NUM> at opposite longitudinal ends of the drum unit <NUM>. The drive-side cover member <NUM> has a support hole 27a, and the outer circumference of the coupling portion 29a of the drum driving member <NUM> is fitted in the support hole 27a. The drive-side cover member <NUM> thus supports the photosensitive drum <NUM>. The non-drive-side cover member <NUM> has a columnar support portion 28a, which is fitted in a hole (not shown) formed in the other end in the longitudinal direction (non-drive side, -Y direction end) of the photosensitive drum <NUM> in the rotational center of the photosensitive drum <NUM>. The non-drive-side cover member <NUM> thus supports the photosensitive drum <NUM>. The drive-side cover member <NUM> and the non-drive-side cover member <NUM> are fixed to the drum frame <NUM> with screws or adhesives (not shown), for example. The drive-side cover member <NUM>, the non-drive-side cover member <NUM>, and the drum frame <NUM> function as a frame that supports the photosensitive drum <NUM>.

A coupling (not shown) serving as a drum drive output portion of the apparatus main body <NUM> engages with the coupling portion 29a of the drum driving member <NUM>, so that the photosensitive drum <NUM> rotatably placed in the drum unit <NUM> receives a rotational force of a drive motor (not shown) of the apparatus main body <NUM>. This rotates the photosensitive drum <NUM> in the direction of arrow Q in <FIG> (clockwise as viewed from the non-drive side).

The charging roller <NUM> is supported by the drum frame <NUM> so as to be rotatable in contact with the photosensitive drum <NUM>. The charging roller <NUM> has a charging roller gear <NUM> at one longitudinal end (drive side, +Y direction end), that is, on the side where the drum driving member <NUM> of the photosensitive drum <NUM> is located. The charging roller gear <NUM> meshes with the gear portion 29b of the drum driving member <NUM>, allowing the charging roller <NUM> to receive the rotational force of the drive motor (not shown) of the apparatus main body <NUM> via the drum driving member <NUM> and thus rotate in the direction of arrow R in <FIG> (counterclockwise as viewed from the non-drive side).

<FIG> and <FIG> are exploded perspective views of the drive-side cover member <NUM>. As shown in <FIG> and <FIG>, the drive-side cover member <NUM> has a columnar support portion 27b and a support hole 27c. The support portion 27b is fitted into a hole 41a of a transmission member <NUM> to rotatably support the transmission member <NUM>. The transmission member <NUM> has a coupling portion 41c, which transmits a rotational force to a development driving member <NUM> supported by the developing unit <NUM>, and a gear portion 41b.

A gear support member <NUM> shown in <FIG> and <FIG> has a columnar support portion 42a. The support portion 42a of the gear support member <NUM> is fitted in a hole 43a of an idler gear <NUM> and the support hole 27c of the drive-side cover member <NUM>. The gear support member <NUM> is fixed to the drive-side cover member <NUM>. The drive-side cover member <NUM> thus rotatably supports the idler gear <NUM>. The gear support member <NUM> is fixed to the drive-side cover member <NUM> with a screw, adhesive, or the like (not shown). The idler gear <NUM> has a gear portion 43b. The gear portion 43b of the idler gear <NUM>, which is rotatably supported by the drive-side cover member <NUM>, is configured to mesh with the gear portion 41b of the transmission member <NUM>. This allows the idler gear <NUM> to transmit a rotational force to the transmission member <NUM>. Also, referring to <FIG>, when the drive-side cover member <NUM> is fixed to the drum frame <NUM>, the gear portion 29b of the drum driving member <NUM> meshes with the gear portion 43b of the idler gear <NUM>, allowing the drum driving member <NUM> to transmit a rotational force to the idler gear <NUM>. That is, the rotational force received by the drum driving member <NUM> from the apparatus main body <NUM> is transmitted to the transmission member <NUM> via the idler gear <NUM>.

Referring to <FIG>, <FIG>, and <FIG>, the configuration of the developing unit <NUM> is now described. <FIG> and <FIG> are exploded perspective views of the developing unit <NUM>. <FIG> shows how a drive-side bearing <NUM> and a non-drive-side bearing <NUM>, which support the developing roller <NUM>, and the stirring member <NUM> are assembled. <FIG> shows how a plurality of gears supported by the developing unit <NUM> and a developing cover member <NUM> are assembled.

As shown in <FIG>, <FIG>, and <FIG>, the developing unit <NUM> includes the developing roller <NUM>, the developing blade <NUM>, and the developing container <NUM>, for example. The developing container <NUM> has the toner containing chamber <NUM>, which stores toner to be supplied to the developing roller <NUM>. The developing blade <NUM> is formed by welding or otherwise joining an elastic member 35b, which is a metal sheet having a thickness of about <NUM>, to a support member 35a, which is a metal material having an L-shaped cross-section. The developing blade <NUM> is fixed to the developing container <NUM> at two locations at one end (drive side, +Y direction end) and the other end (non-drive side, -Y direction end) in the longitudinal direction (rotation axis direction, Y direction) with screws or the like. The elastic member 35b of the developing blade <NUM> is in contact with the developing roller <NUM> under a predetermined pressure, thereby regulating the thickness of the toner layer on the circumference surface of the developing roller <NUM>. That is, when the developing roller <NUM> rotates, a frictional force is generated between the developing roller <NUM> and the developing blade <NUM>, resulting in a rotation load applied to the developing roller <NUM>.

As shown in <FIG>, the core bar 31a of the developing roller <NUM> is fitted in a support hole 37b of the drive-side bearing <NUM> and a support hole 38b of the non-drive-side bearing <NUM>, which are attached to opposite longitudinal ends of the developing container <NUM>. The developing unit <NUM> thus rotatably supports the developing roller <NUM>. Also, the core bar 33a of the supply roller <NUM> is fitted in a support hole 37c of the drive-side bearing <NUM> and a support hole 38c of the non-drive-side bearing <NUM>, and the developing unit <NUM> thus rotatably supports the supply roller <NUM>. Furthermore, as shown in <FIG>, a developing roller gear <NUM> is placed at one end (drive side, +Y direction end) of the developing roller <NUM> in the longitudinal direction (rotation axis direction, Y direction). A rotational force that causes the core bar 31a to rotate the developing roller <NUM> is input to this developing roller gear <NUM>. A supply roller gear <NUM> is placed at one end (drive side, +Y direction end) of the supply roller <NUM> in the longitudinal direction (rotation axis direction, Y direction). A rotational force that causes the core bar 33a to rotate the supply roller <NUM> is input to this supply roller gear <NUM>.

<FIG> and <FIG> are perspective views of the development driving member <NUM>. As shown in <FIG> and <FIG>, the developing unit <NUM> has the development driving member (transmitted member, driven member) <NUM>, which receives a rotational force transmitted from the transmission member <NUM>. The development driving member <NUM> has a coupling portion 45d, which engages with the coupling portion 41c of the transmission member <NUM> to transmit a rotational force. The development driving member <NUM> also has a first gear portion 45a and a second gear portion 45b around the coupling portion 45d. It also has a hole 45c at the inner side of the first and second gear portions 45a and 45b. That is, the transmission member <NUM> is configured to transmit the rotational force received by the drum driving member <NUM> to the development driving member <NUM> of the developing unit <NUM>. As will be described below, the development driving member <NUM> is rotatable about a developing rotation axis N. The transmission member <NUM> and the development driving member <NUM> are arranged in a direction of the developing rotation axis N and face each other.

As shown in <FIG>, the drive-side bearing <NUM> has a columnar support portion 37a, which is fitted in the hole 45c of the development driving member <NUM>. The developing cover member <NUM> has a hole 46a, which fits the outer circumference of the coupling portion 45d of the development driving member <NUM>. In this manner, the drive-side bearing <NUM> and the developing cover member <NUM> rotatably support the development driving member <NUM>.

The first gear portion 45a of the development driving member <NUM>, which is rotatably supported by the developing unit <NUM> as described above, meshes with the developing roller gear <NUM> and transmits a rotational force to the developing roller gear <NUM>. Also, the second gear portion 45b of the development driving member <NUM> meshes with the supply roller gear <NUM> and transmits a rotational force to the supply roller gear <NUM>. That is, the rotational force received by the development driving member <NUM> from the transmission member <NUM> is transmitted to the developing roller gear <NUM> and the supply roller gear <NUM>, thereby rotating the developing roller <NUM> in the direction of arrow S in <FIG> and the supply roller <NUM> in the direction of arrow T in <FIG>.

The developing container <NUM> has the toner containing chamber <NUM>, which is a containing portion containing toner. The toner containing chamber <NUM> accommodates the stirring member <NUM>, which rotates in the containing portion to stir the developer. The stirring member <NUM> has a sheet-shaped stirring elastic member 34a and a stirring shaft 34b to which one end of the stirring elastic member 34a is fixed. As shown in <FIG>, a support hole 34d is provided at one end (drive side, +Y direction end) of the stirring shaft 34b in the longitudinal direction (rotation axis direction, Y direction), and a columnar support portion 34c is provided at the other end (non-drive side, -Y direction end). The support portion 34c engages with an arcuate portion 32b provided in the inner wall of the developing container <NUM>, and the support hole 34d engages with a support portion 48a, which has the shape of a quadratic prism, of a stirring gear <NUM>, which is placed from the outside of the developing container <NUM>. Thus, the stirring member <NUM> placed in the toner containing chamber <NUM> is rotatably supported. As shown in <FIG>, a lid 32c is fixed to the developing container <NUM> by ultrasonic welding, an adhesive, or the like, so that the developing container <NUM> forms the toner containing chamber <NUM>. A toner receiving portion 32a, which is placed on the lid 32c, defines therein a toner path communicating with the toner containing chamber <NUM>. The toner pack <NUM> is placed on this toner receiving portion 32a to replenish the toner containing chamber <NUM> of the developing unit <NUM> with toner.

The stirring gear <NUM> has a gear portion 48b. The inner circumference of the gear portion 48b engages with an annular support portion 32d of the developing container <NUM> as shown in <FIG> and is thus rotatably supported by the developing container <NUM>. As shown in <FIG>, a stirring idler gear <NUM> has a first gear portion 47a, a second gear portion 47b, and a hole 47c extending through the first and second gear portions 47a and 47b. The hole 47c engages with a columnar support portion 46b of the developing cover member <NUM> fixed to the developing container <NUM> and is thus rotatably supported. The first gear portion 47a of the stirring idler gear <NUM>, which is placed on the developing container <NUM>, meshes with the second gear portion 45b of the development driving member <NUM>, and the second gear portion 47b meshes with the gear portion 48b of the stirring gear <NUM>. That is, the rotational force received by the development driving member <NUM> is transmitted to the stirring gear <NUM> via the stirring idler gear <NUM>, rotating the stirring member <NUM> in the direction of arrow U in <FIG>.

Referring to <FIG> and <FIG>, a configuration is now described in which the drum unit <NUM> and the developing unit <NUM> are combined. <FIG> and <FIG> are exploded perspective views of the process cartridge <NUM>. <FIG> shows how the drive-side cover member <NUM> is attached, and <FIG> shows how the non-drive-side cover member <NUM> is attached. The rotational center of the development driving member <NUM> rotatably supported by the developing unit <NUM> is referred to as the developing rotation axis N.

As shown in <FIG>, the developing cover member <NUM> fixed to the developing unit <NUM> has an annular support portion 46c. The annular support portion 46c is coaxial with the hole 46a that supports the development driving member <NUM>, and the center of the annular support portion 46c coincides with the developing rotation axis N. Also, as shown in <FIG>, the non-drive-side bearing <NUM> fixed to the developing container <NUM> has a columnar support portion 38d, the center of which coincides with the developing rotation axis N.

The developing unit <NUM> is joined to the drum unit <NUM> so as to be movable relative to the drum unit <NUM>. As shown in <FIG>, the annular support portion 46c engages with a developing support portion 27d of the drive-side cover member <NUM>. As shown in <FIG>, the support portion 38d engages with a developing support portion 28b, which has the shape of an elongate hole, of the non-drive-side cover member <NUM>. As a result, the developing unit <NUM> rotatably supported by the drive-side cover member <NUM> and the non-drive-side cover member <NUM> is rotatable relative to the drum unit <NUM> about the developing rotation axis N as the rotational center. The rotational center of the development driving member <NUM> coincides with the rotational center of the developing unit <NUM> on the developing rotation axis N. Additionally, the rotational centers of the development driving member <NUM> and the transmission member <NUM> also coincide on the developing rotation axis N, and the coupling portion 41c of the transmission member <NUM> engages with the coupling portion 45d of the development driving member <NUM>, allowing a rotational force to be transmitted from the transmission member <NUM> to the development driving member <NUM>.

Referring to <FIG>, the rotational force transmission path of the process cartridge <NUM> is now described in more detail. <FIG> and <FIG> are side views of the process cartridge <NUM> placed in the apparatus main body <NUM> as viewed from the side on which the drum driving member <NUM> is placed (drive side, +Y direction end) in the longitudinal direction (rotation axis direction, Y direction) of the photosensitive drum <NUM>. <FIG> shows a state where the developing unit <NUM> is located in a development position (first position) in which the developing roller <NUM> is in contact with the photosensitive drum <NUM>. <FIG> shows a state where the developing unit <NUM> is located in a retraction position (second position) in which the developing roller <NUM> is spaced from the photosensitive drum <NUM>. <FIG> do not show the drive-side cover member <NUM>, the non-drive-side cover member <NUM>, the drive-side bearing <NUM>, or the developing cover member <NUM>.

The developing unit <NUM> is supported so as to be rotatable relative to the drum unit <NUM> about the developing rotation axis N in <FIG> and <FIG>. In other words, the developing unit <NUM> can swing about the developing rotation axis (axis) N relative to the drum unit <NUM> so as to move between the development position and the retraction position. As shown in <FIG>, when the developing unit <NUM> is in the development position, the developing roller <NUM> is in contact with the photosensitive drum <NUM> and can develop the latent image on the surface of the photosensitive drum <NUM>. A retraction cam <NUM> is placed in the apparatus main body <NUM> below the toner receiving portion 32a. When the developing unit <NUM> is in the development position, there is a gap H shown in <FIG> between the retraction cam <NUM> and the bottom surface 32f of the toner receiving portion 32a. Also, the developing roller gear <NUM> is separated from the drum driving member <NUM>.

With the developing unit <NUM> located in the development position, a rotational force input to the coupling portion 29a of the drum driving member <NUM> in the direction of arrow Q in <FIG> (counterclockwise as viewed from the drive side in the -Y direction) rotates the photosensitive drum <NUM> in the direction of arrow Q in <FIG>. The charging roller <NUM>, on which the charging roller gear <NUM> meshing with the gear portion 29b of the drum driving member <NUM> is placed, rotates in the direction of arrow R in <FIG> (clockwise as viewed from the drive side in the -Y direction). Also, the idler gear <NUM>, which meshes with the gear portion 29b of the drum driving member <NUM>, rotates, and the transmission member <NUM>, which meshes with the idler gear <NUM>, rotates about the developing rotation axis N in the direction of arrow K1 in <FIG> (counterclockwise as viewed from the drive side in the -Y direction). Furthermore, the coupling portion 41c of the transmission member <NUM>, which engages with the coupling portion 45d of the development driving member <NUM>, transmits the rotational force to the coupling portion 45d, so that the development driving member <NUM> rotates in the direction of arrow K1 in <FIG> (counterclockwise as viewed from the drive side in the -Y direction).

As shown in <FIG>, the first gear portion 45a of the development driving member <NUM>, which is driven by the transmission member <NUM>, meshes with the developing roller gear <NUM> to rotate the developing roller <NUM> in the direction of arrow S in <FIG> (clockwise as viewed from the drive side in the -Y direction). Also, the second gear portion 45b (not shown) meshes with the supply roller gear <NUM> to rotate the supply roller <NUM> (not shown) in the direction of arrow T in <FIG> (clockwise as viewed from the drive side in the -Y direction). The second gear portion 45b (not shown) also meshes with the stirring idler gear <NUM>, which meshes with the stirring gear <NUM>, so that the stirring gear <NUM> and the stirring member <NUM> (not shown) are rotated in the direction of arrow U in <FIG> (counterclockwise as viewed from the drive side in the -Y direction). In this manner, the development driving member <NUM> transmits the rotational force to the developing roller <NUM>, the supply roller <NUM>, and the stirring member <NUM>, which are rotating members of the developing unit <NUM>. In other words, the developing roller <NUM>, the supply roller <NUM>, and the stirring member <NUM> are rotated by the rotational force transmitted to the development driving member <NUM> of the developing unit <NUM> by the transmission member <NUM>. This eliminates the need for a configuration for directly transmitting a rotational force from the apparatus main body <NUM> to the developing unit <NUM>.

Accordingly, the rotation loads of the rotating members of the developing unit <NUM> are applied to the development driving member <NUM>, and the rotation loads of the rotating members of the developing unit <NUM> is also applied to the transmission member <NUM>, which rotates the development driving member <NUM>. Additionally, the rotation loads of the rotating members of the developing unit <NUM> is also applied to the drum driving member <NUM>, which rotates the transmission member <NUM> via the idler gear <NUM>. As a result, the rotation load caused by the rotating members of the developing unit <NUM> is applied to the drum driving member <NUM>, allowing the drum driving member <NUM> to rotate in a stable manner as compared with a configuration in which the drum driving member <NUM> rotates under light-load conditions. This stabilizes the rotation of the photosensitive drum <NUM>.

In the first embodiment, the transmission member <NUM>, the idler gear <NUM>, the development driving member <NUM>, and the stirring idler gear <NUM> serve as transmission means for transmitting the rotational driving force input to the photosensitive drum <NUM> to the developing roller <NUM>, the supply roller <NUM>, and the stirring member <NUM>. The transmission means may be any configuration that transmits the rotational driving force input to the photosensitive drum <NUM> via the drum driving member <NUM> to the rotating member of at least one of the developing roller <NUM>, the supply roller <NUM>, and the stirring member <NUM>. As a result, the load for rotating the rotating members is applied to the drum driving member <NUM>, advantageously stabilizing the rotation of the photosensitive drum <NUM>. In the first embodiment, the idler gear <NUM> and the transmission member <NUM> function as first gears that are driven and rotated by the drum driving member <NUM>. That is, the idler gear <NUM> and the transmission member <NUM> are driven and rotated in interrelation with the rotation of the photosensitive drum <NUM> (the rotation of the drum driving member <NUM>). The development driving member <NUM> and the stirring idler gear <NUM> function as second gears that are rotatably supported by the developing unit <NUM> and driven and rotated by the first gears. The means for transmitting the rotational driving force input to the photosensitive drum <NUM> to the rotating members, such as the developing roller <NUM>, of the developing unit <NUM> is not limited to the above example and may be any configuration that allows the rotation loads of the rotating members to be applied to the drum driving member <NUM>. The first embodiment illustrates an example configuration in which the transmission member <NUM> as the first gear is connected to the development driving member <NUM> as the second gear via the coupling (41c, 45d), but the form of connection is not limited to this as long as the rotational driving force can be transmitted.

The rotational force transmitted by the transmission member <NUM> to the development driving member <NUM> acts as an external force applied to the developing unit <NUM>, causing the developing unit <NUM> to rotate about the developing rotation axis N in the direction of arrow K1 in <FIG> (counterclockwise as viewed from the drive side in the -Y direction). As a result, the developing roller <NUM> of the developing unit <NUM> receives a force acting in the counterclockwise direction about the developing rotation axis N. Thus, the developing roller <NUM> is pressed against the photosensitive drum <NUM>, which is located downstream of the developing roller <NUM> in the counterclockwise direction about the developing rotation axis N, so that the developing roller <NUM> is in contact with the photosensitive drum <NUM>. In this manner, the drum unit <NUM> and the developing unit <NUM> are joined together so as to be relatively rotatable about the axis N parallel to the rotation axis of the development driving member <NUM> as the second gear and between the first position in which the developing roller <NUM> is in contact with the photosensitive drum <NUM> and the second position in which the developing roller <NUM> is spaced from the photosensitive drum <NUM>. The developing roller <NUM> is located upstream of the photosensitive drum <NUM> in the direction in which the development driving member <NUM> as the second gear rotates when a rotational driving force is transmitted by the transmission member <NUM> and the development driving member <NUM>, which are transmission means. Thus, when a rotational driving force is input to the drum driving member <NUM>, a force that urges the developing roller <NUM> toward the photosensitive drum <NUM> acts on the developing unit <NUM>. This brings the developing roller <NUM> into contact with the photosensitive drum <NUM>.

When the opening and closing member <NUM> shown in <FIG> is moved from the closed position to the open position, the retraction cam <NUM> moves in the direction of arrow J in <FIG> (clockwise as viewed from the drive side in the -Y direction) in conjunction with the opening and closing member <NUM>. This brings the retraction cam <NUM> into contact with the bottom surface 32f of the toner receiving portion 32a as shown in <FIG>. The bottom surface 32f is thus pressed in the direction of arrow F in <FIG> (the direction perpendicular to the bottom surface 32f), the developing unit <NUM> rotates about the developing rotation axis N in the direction of arrow K2 in <FIG> (clockwise as viewed from the drive side in the -Y direction), and the developing unit <NUM> moves to the retraction position. At this time, as shown in <FIG>, a gap V is formed between the developing roller <NUM> and the photosensitive drum <NUM>, separating the developing roller <NUM> from the photosensitive drum <NUM>. The retraction cam <NUM> is an interlocking mechanism that moves the developing unit <NUM> relative to the drum unit <NUM> between the first position (development position) and the second position (retraction position) in conjunction with the opening and closing of the opening and closing member <NUM>. When the opening and closing member <NUM> opens the opening portion 82a, the retraction cam <NUM> moves the developing unit <NUM> to the second position. When the opening and closing member <NUM> closes the opening portion 82a, the developing unit <NUM> moves to the first position.

When the developing unit <NUM> is in the retraction position, the meshing relationship between the gear portions of the drum unit <NUM> and the developing unit <NUM> remains unchanged. The engagement between the transmission member <NUM> and the development driving member <NUM> is maintained while the developing unit <NUM> moves between the development position and the retraction position. That is, the developing unit <NUM> moves between the development position and the retraction position with the transmission member <NUM> and the development driving member <NUM> remaining engaged. When the developing unit <NUM> is in the retraction position, in the same manner as when the developing unit <NUM> is in the development position, the coupling portion 41c of the transmission member <NUM> engages with the coupling portion 45d of the development driving member <NUM>, allowing the transmission member <NUM> to drive the development driving member <NUM>. As such, the rotational force input to the drum driving member <NUM> in the direction of arrow Q in <FIG> (counterclockwise as viewed from the drive side in the -Y direction) is transmitted to the development driving member <NUM> from the transmission member <NUM> in the same manner as when the developing unit <NUM> is in the development position. The rotational force is then transmitted to the rotating members (the developing roller <NUM>, the supply roller <NUM>, and the stirring member <NUM>) placed in the developing unit <NUM>. That is, the transmission member <NUM> can transmit the rotational force to the developing unit <NUM> in the development position and the developing unit <NUM> in the separated position.

As a result, even when the developing unit <NUM> is located in the retraction position and the developing roller <NUM> is separated from the photosensitive drum <NUM>, the loads of the rotating members of the developing unit <NUM> are applied to the drum driving member <NUM>, allowing the photosensitive drum <NUM> to rotate in a stable manner. The configuration also allows the rotational force to be transmitted to the rotating members of the developing unit <NUM> with the developing roller <NUM> separated from the photosensitive drum <NUM>. As such, the toner added to the toner containing chamber <NUM> from the toner receiving portion 32a is stirred by the stirring member <NUM> and supplied to the supply roller <NUM> and the developing roller <NUM> without causing deterioration of the developing roller <NUM>, which would otherwise occur due to friction with the photosensitive drum <NUM>. Furthermore, the developing roller <NUM> may be brought into contact with the photosensitive drum <NUM> while the photosensitive drum <NUM> is rotating. In this case, the rotation of the photosensitive drum <NUM> rotates the developing roller <NUM>, allowing the developing roller <NUM> to be in contact with the photosensitive drum <NUM> while rotating.

The first embodiment illustrates a configuration in which a rotational force is input to the development driving member <NUM> of the developing unit <NUM> via the transmission member <NUM> to rotate the developing unit <NUM> relative to the drum unit <NUM>, thereby bringing the developing roller <NUM> into contact with the photosensitive drum <NUM>. However, the configuration for bringing the developing roller <NUM> into contact with the photosensitive drum <NUM> is not limited to this. For example, a configuration may be contemplated that uses a spring to urge the developing unit <NUM> toward the drum unit <NUM> to bring the developing roller <NUM> into contact with the photosensitive drum <NUM>. This configuration is described below with reference to <FIG>.

<FIG> is a side view of the process cartridge <NUM> placed in the apparatus main body <NUM>, as viewed in a direction along the rotation axis of the photosensitive drum <NUM> (Y direction) from the side on which the non-drive-side cover member <NUM> is placed. The non-drive-side cover member <NUM> of the drum unit <NUM> has a protruding spring hook portion 28c, and the non-drive-side bearing <NUM> of the developing unit <NUM> has a protruding spring hook portion 38e. A development pressurizing spring <NUM> is placed on the spring hook portions 28c and 38e, so that a force acts on the developing unit <NUM> in the direction of arrow G in <FIG> (the direction that urges the developing unit <NUM> clockwise about the developing rotation axis N). The developing unit <NUM> receives the force in the direction of arrow G in <FIG> and rotates about the developing rotation axis N in the direction of arrow K1 in <FIG> (clockwise as viewed from the non-drive side in the +Y direction), so that the developing roller <NUM> of the developing unit <NUM> is in contact with the photosensitive drum <NUM>. As described above, instead of transmitting the rotational force to the development driving member <NUM>, a spring may be used to generate contact pressure that brings the developing roller <NUM> into contact with the photosensitive drum <NUM>.

A process cartridge and an image forming apparatus according to a second embodiment of the present invention are now described. In the second embodiment, members having the same functions and configurations as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and a detailed description thereof will be omitted.

<FIG> is an exploded perspective view of a drive-side cover member <NUM>. The drive-side cover member <NUM> has a columnar support portion 227b. The support portion 227b is fitted in a hole 241a of a transmission member <NUM> to support the transmission member <NUM>. The transmission member <NUM> rotatably supported by the support portion 227b includes a gear portion 241b that transmits a rotational force to the developing unit <NUM>.

<FIG> and <FIG> are exploded perspective views of the developing unit <NUM> according to the second embodiment. A development driving member (transmitted member, driven member) <NUM> includes a first gear portion 245a and a second gear portion 245b. As in the first embodiment, the first gear portion 245a meshes with the developing roller gear <NUM>, and the second gear portion 245b meshes with the supply roller gear <NUM> and the stirring idler gear <NUM> to transmit a rotational force. The development driving member <NUM> also includes a third gear portion 245e, which meshes with the gear portion 241b of the transmission member <NUM> and transmits a rotational force. The development driving member <NUM> has a hole 245c, which fits the support portion 37a of the drive-side bearing <NUM> and the columnar support portion 246b of the developing cover member <NUM>, so that the development driving member <NUM> is rotatably supported.

Referring to <FIG>, a configuration is now described in which the drum unit <NUM> and the developing unit <NUM> are combined. <FIG> is an exploded perspective view of the process cartridge <NUM> according to the second embodiment. The rotational center of the development driving member <NUM>, which is rotatably supported, is referred to as a developing rotation axis N as in the first embodiment. The developing cover member <NUM> fixed to the developing unit <NUM> has a columnar support portion 246c. The columnar support portion 246c is coaxial with the support portion 246b, which supports the development driving member <NUM> and is shown in <FIG>, and the center of the columnar support portion 246c coincides with the developing rotation axis N. The columnar support portion 246c engages with the developing support portion 227d of the drive-side cover member <NUM>, the developing unit <NUM> is thus supported so as to be rotatable relative to the drum unit <NUM> about the developing rotation axis N as the rotational center in the same manner as the first embodiment. The rotational center of the development driving member <NUM> coincides with the rotational center of the developing unit <NUM> on the developing rotation axis N. As in the first embodiment, the support hole 227a of the drive-side cover member <NUM> fits the outer circumference of the coupling portion 29a of the drum driving member <NUM>, and the drive-side cover member <NUM> supports the photosensitive drum <NUM> on which the drum driving member <NUM> is placed. The gear portion 29b of the drum driving member <NUM> meshes with the gear portion 241b of the transmission member <NUM>, and the gear portion 241b of the transmission member <NUM> meshes with the third gear portion 245e of the development driving member <NUM>. That is, the rotational force input to the drum driving member <NUM> is transmitted to the development driving member <NUM> via the transmission member <NUM>.

Referring to <FIG> and <FIG>, the rotational force transmission path of the process cartridge <NUM> of the second embodiment is now described in more detail. <FIG> and <FIG> are side views of the process cartridge <NUM> placed in the apparatus main body <NUM> as viewed from the side on which the drum driving member <NUM> is placed (drive side, +Y direction end) in the longitudinal direction of the photosensitive drum <NUM> (rotation axis direction, Y direction). <FIG> shows a state where the developing unit <NUM> is located in a development position in which the developing roller <NUM> is in contact with the photosensitive drum <NUM>. <FIG> shows a state where the developing unit <NUM> is located in a retraction position in which the developing roller <NUM> is spaced from the photosensitive drum <NUM>. <FIG> do not show the drive-side cover member <NUM>, the non-drive-side cover member <NUM>, the drive-side bearing <NUM>, or the developing cover member <NUM>.

As shown in <FIG>, with the developing unit <NUM> located in the development position, a rotational force is input to the coupling portion 29a of the drum driving member <NUM> in the direction of arrow Q in <FIG> (counterclockwise as viewed from the drive side in the -Y direction). This rotates the photosensitive drum <NUM>, on which the drum driving member <NUM> is placed, in the direction of arrow Q in <FIG> (counterclockwise as viewed from the drive side in the -Y direction). The charging roller gear <NUM>, which meshes with the gear portion 29b of the drum driving member <NUM>, and the charging roller <NUM>, on which the charging roller gear <NUM> is placed, rotate in the direction of arrow R in <FIG> (clockwise as viewed from the drive side in the -Y direction). Furthermore, the gear portion 29b of the drum driving member <NUM> meshes with the gear portion 241b of the transmission member <NUM>, rotating the transmission member <NUM>. The gear portion 241b of the transmission member <NUM> meshes with the third gear portion 245e of the development driving member <NUM>, and the development driving member <NUM> rotates about the developing rotation axis N in the direction of arrow K1 in <FIG> (counterclockwise as viewed from the drive side in the -Y direction). That is, the transmission member <NUM> is configured to transmit the rotational force received by the drum driving member <NUM> to the development driving member <NUM> of the developing unit <NUM>.

As in the first embodiment, the first gear portion 245a of the development driving member <NUM>, which is driven by the transmission member <NUM>, transmits the rotational force to the developing roller gear <NUM>, rotating the developing roller <NUM> in the direction of arrow S in <FIG> (clockwise as viewed from the drive side in the -Y direction). Also, the second gear portion 245b of the development driving member <NUM> transmits the rotational force to the supply roller gear <NUM> and the stirring idler gear <NUM>, thereby rotating the supply roller <NUM> in the direction of arrow T in <FIG> (clockwise as viewed from the drive side in the -Y direction). Additionally, the stirring member <NUM> is rotated in the direction of arrow U in <FIG> (counterclockwise as viewed from the drive side in the -Y direction).

Accordingly, as in the first embodiment, the rotation loads of the rotating members of the developing unit <NUM> are applied to the development driving member <NUM>, and the rotation loads of the rotating members of the developing unit <NUM> are also applied to the transmission member <NUM>, which rotates the development driving member <NUM>. Furthermore, the rotation loads of the rotating members of the developing unit <NUM> are also applied to the drum driving member <NUM>, which rotates the transmission member <NUM>. As a result, the rotation loads caused by the rotating members of the developing unit <NUM> are applied to the drum driving member <NUM>, allowing the drum driving member <NUM> to rotate in a stable manner as compared with a configuration in which the drum driving member <NUM> rotates under light-load conditions. This stabilizes the rotation of the photosensitive drum <NUM>.

In the second embodiment, the transmission member <NUM>, the development driving member <NUM>, and the stirring idler gear <NUM> serve as transmission means for transmitting the rotational driving force input to the photosensitive drum <NUM> via the drum driving member <NUM> to the developing roller <NUM>, the supply roller <NUM>, and the stirring member <NUM>. The transmission means may be any configuration that transmits the rotational driving force input to the photosensitive drum <NUM> via the drum driving member <NUM> to the rotating member of at least one of the developing roller <NUM>, the supply roller <NUM>, and the stirring member <NUM>. As a result, the load for rotating the rotating members is applied to the drum driving member <NUM>, advantageously stabilizing the rotation of the photosensitive drum <NUM>. In the second embodiment, the transmission member <NUM> functions as the first gear that is driven and rotated by the drum driving member <NUM>. That is, the transmission member <NUM> is driven and rotated in interrelation with the rotation of the photosensitive drum <NUM> (the rotation of the drum driving member <NUM>). Additionally, the development driving member <NUM> and the stirring idler gear <NUM> function as the second gears that are rotatably supported by the developing unit <NUM> and driven and rotated by the first gear. The means for transmitting the rotational driving force input to the photosensitive drum <NUM> to the rotating members, such as the developing roller <NUM>, of the developing unit <NUM> is not limited to the above example and may be any configuration that allows the rotation loads of the rotating members to be applied to the drum driving member <NUM>.

As in the first embodiment, the developing unit <NUM> receives a rotational force as an external force in the direction of arrow K1 in <FIG> (counterclockwise as viewed from the drive side in the -Y direction). This rotates the developing unit <NUM> about the developing rotation axis N in the direction of arrow K1 in 14A (counterclockwise as viewed from the drive side in the -Y direction). As a result, a counterclockwise force acts about the developing rotation axis N. Thus, the developing roller <NUM> is pressed against the photosensitive drum <NUM>, which is located downstream of the developing roller <NUM> in the counterclockwise direction about the developing rotation axis N, so that the developing roller <NUM> is in contact with the photosensitive drum <NUM>. In this manner, the drum unit <NUM> and the developing unit <NUM> are joined together so as to be relatively rotatable about the axis N parallel to the rotation axis of the development driving member <NUM> as the second gear and between the first position in which the developing roller <NUM> is in contact with the photosensitive drum <NUM> and the second position in which the developing roller <NUM> is spaced from the photosensitive drum <NUM>. The developing roller <NUM> is located upstream of the photosensitive drum <NUM> in the direction in which the development driving member <NUM> as the second gear rotates when a rotational driving force is transmitted by the transmission member <NUM> and the development driving member <NUM>, which are transmission means. Thus, when a rotational driving force is input to the drum driving member <NUM>, a force that urges the developing roller <NUM> toward the photosensitive drum <NUM> acts on the developing unit <NUM>. This brings the developing roller <NUM> into contact with the photosensitive drum <NUM>.

<FIG> shows a state in which the bottom surface 32f of the toner receiving portion 32a of the developing unit <NUM> is pressed upward by the retraction cam <NUM> (not shown in <FIG>) having the same configuration as in <FIG> and <FIG> in the same manner as the first embodiment. The retraction cam <NUM> rotates the developing unit <NUM> about the developing rotation axis N in the direction of arrow K2 in <FIG> (clockwise as viewed from the drive side in the -Y direction) and thus moves the developing unit <NUM> to the retraction position. At this time, a gap V is formed between the developing roller <NUM> and the photosensitive drum <NUM>, separating the developing roller <NUM> from the photosensitive drum <NUM>.

As in the first embodiment, when the developing unit <NUM> is in the retraction position, the meshing relationship between the gear portions of the drum unit <NUM> and the developing unit <NUM> remains unchanged. The engagement between the transmission member <NUM> and the development driving member <NUM> is maintained while the developing unit <NUM> moves between the development position and the retraction position. That is, the developing unit <NUM> moves between the development position and the retraction position with the transmission member <NUM> and the development driving member <NUM> remaining engaged. When the developing unit <NUM> is in the retraction position, in the same manner as when the developing unit <NUM> is in the development position, the gear portion 241b of the transmission member <NUM> engages (meshes) with the third gear portion 245e of the development driving member <NUM>, allowing the transmission member <NUM> to drive the development driving member <NUM>. As such, the rotational force input to the drum driving member <NUM> in the direction of arrow Q in <FIG> (counterclockwise as viewed from the drive side in the -Y direction) is transmitted to the development driving member <NUM> from the transmission member <NUM> in the same manner as when the developing unit <NUM> is in the development position. The rotational force is then transmitted to the rotating members placed in the developing unit <NUM>. That is, the transmission member <NUM> can transmit the rotational force to the developing unit <NUM> in the development position and the developing unit <NUM> in the separated position.

As a result, even when the developing unit <NUM> is located in the retraction position and the developing roller <NUM> is separated from the photosensitive drum <NUM>, the loads of the rotating members of the developing unit <NUM> are applied to the drum driving member <NUM>, allowing the photosensitive drum <NUM> to rotate in a stable manner. The configuration also allows the rotational force to be transmitted to the rotating members of the developing unit <NUM> with the developing roller <NUM> separated from the photosensitive drum <NUM>. As such, the toner added to the toner containing chamber <NUM> from the toner receiving portion 32a is stirred by the stirring member <NUM> and supplied to the supply roller <NUM> and the developing roller <NUM> without causing deterioration of the developing roller <NUM>, which would otherwise occur due to friction with the photosensitive drum <NUM>. As compared with the first embodiment, the second embodiment can omit the idler gear <NUM>, resulting in a simpler configuration and improved assembly.

Claim 1:
A process unit (<NUM>) comprising:
a photosensitive member unit (<NUM>) including a photosensitive member (<NUM>) on which an electrostatic latent image is to be formed and a drive receiving portion (<NUM>) configured to receive a driving force for rotating the photosensitive member;
a developing unit (<NUM>) that is joined to the photosensitive member unit so as to be movable relative to the photosensitive member unit and includes a developing roller (<NUM>) configured to develop the electrostatic latent image with a developer, wherein the developing unit is configured to be movable relative to the photosensitive member unit between a first position in which the developing roller is in contact with the photosensitive member and a second position in which the developing roller is spaced from the photosensitive member; and
a transmission member (<NUM>) configured to transmit the driving force received by the drive receiving portion to the developing unit, wherein
the developing unit has a driven member (<NUM>) configured to be driven by the transmission member, and
the transmission member is configured to engage with the driven member to drive the driven member with the developing unit located in the first position, and to engage with the driven member to drive the driven member with the developing unit located in the second position.