Patent Description:
A development cartridge contains toner and supplies the toner to the electrostatic latent image formed on the photoconductor to form the visible toner image. In certain circumstances, such as when the toner contained in the development cartridge is used up, the development cartridge may be removed from a main body of the image forming apparatus and a new development cartridge may be mounted in the main body. <CIT> discloses an the image forming apparatus wherein a bellows-like pipe is provided connecting a toner storage part and a developing unit.

Reference will now be made to examples that are illustrated in the accompanying drawings. The same reference numerals are used to denote the same elements, and repeated descriptions thereof will not be given herein.

<FIG> is a schematic configuration diagram of an electrophotographic image forming apparatus, according to an example. In the following example, the image forming apparatus prints a color image on a print medium P by using an electrophotographic method.

Referring to <FIG>, the image forming apparatus may include a development cartridge <NUM>, a photoconductive cartridge <NUM>, an optical scanner <NUM>, a transfer unit, and a fuser <NUM>.

The photoconductive cartridge <NUM> may include a photosensitive drum <NUM>. The photosensitive drum <NUM> is an example of a photoconductor that may have an electrostatic latent image formed on a surface thereof, and may include a conductive metal pipe and a photosensitive layer on an outer circumference of the conductive metal pipe. A charging roller <NUM> is an example of a charger to charge the photosensitive drum <NUM> such that the photosensitive drum <NUM> has a uniform surface electric potential. A charging brush, a corona charger, or the like may be used instead of the charging roller <NUM>. A cleaning member <NUM> may remove foreign substances remaining on the surface of the photosensitive drum <NUM> after an intermediate transfer process, an example of which will be described later. Although not illustrated in the drawing, the photoconductive cartridge <NUM> may further include a charging roller cleaner to remove foreign substances such as a developing agent or dust from the charging roller <NUM>.

The development cartridge <NUM> includes a developing roller <NUM>. The developing roller <NUM> is to develop the electrostatic latent image into a visible toner image by supplying a toner to the electrostatic latent image formed on the photosensitive drum <NUM>. Although not illustrated in the drawing, the development cartridge <NUM> may further include a regulating member to regulate an amount of a developing agent supplied to a development area where the photosensitive drum <NUM> and the developing roller <NUM> face each other. The development cartridge <NUM> according to an example may form a toner image by using a two-component developing method in which a toner and a carrier are used as a developing agent. The developing roller <NUM> may be arranged apart from the photosensitive drum <NUM>. A distance between an outer circumferential surface of the developing roller <NUM> and an outer circumferential surface of the photosensitive drum <NUM> may be, for example, about tens to about hundreds of micrometers. The developing roller <NUM> may include a rotating development sleeve and a magnet arranged fixedly inside the development sleeve (so as not to rotate). The toner and the carrier may be mixed in the development cartridge <NUM>, and the toner is attached to a surface of a magnetic carrier. The magnetic carrier is attached to a surface of the developing roller <NUM> to be transported to the development area where the photosensitive drum <NUM> and the developing roller <NUM> face each other. The regulating member (not shown) is to regulate an amount of the developing agent transported to the development area. According to a development bias voltage applied between the developing roller <NUM> and the photosensitive drum <NUM>, toner may be supplied to the photosensitive drum <NUM> to develop the electrostatic latent image formed on the surface of the photosensitive drum <NUM>, into a visible toner image.

For color printing, the development cartridge <NUM> may include a plurality of development cartridges 2C, <NUM>, 2Y, and <NUM> for respectively forming color images of cyan (C), magenta (M), yellow (Y), and black (K) colors. Hereinafter, unless otherwise stated, reference numerals labeled with C, M, Y, and K respectively refer to components for developing agents of cyan (C), magenta (M), yellow (Y), and black (K) colors.

The optical scanner <NUM> may form an electrostatic latent image on the photosensitive drum <NUM> by irradiating the photosensitive drum <NUM> with light modulated in correspondence with image information. As the optical scanner <NUM>, a laser scanning unit (LSU) using a laser diode as a light source, a light emitting diode (LED) optical scanner using an LED as a light source, or the like may be used.

The transfer unit may transfer the toner image formed on the photosensitive drum <NUM> onto the print medium P. In an example, a transfer unit using an intermediate transfer method is used. For example, the transfer unit may include an intermediate transfer belt <NUM>, an intermediate transfer roller <NUM>, and a transfer roller <NUM>.

The intermediate transfer belt <NUM> is to temporarily accommodate the toner image developed on the photosensitive drum <NUM> of a plurality of photoconductive cartridges 3C, <NUM>, 3Y, and <NUM>. A plurality of intermediate transfer rollers <NUM> may be arranged at a position facing the photosensitive drum <NUM> of the plurality of photoconductive cartridges 3C, <NUM>, 3Y, and <NUM>, with the intermediate transfer belt <NUM> therebetween. An intermediate transfer bias voltage for intermediately transferring the toner image developed on the photosensitive drum <NUM>, to the intermediate transfer belt <NUM>, may be applied to the plurality of intermediate transfer rollers <NUM>. Instead of the intermediate transfer rollers <NUM>, a corona transfer unit or a pin scorotron-type transfer unit may be used.

The transfer roller <NUM> is positioned to face the intermediate transfer belt <NUM>. A transfer bias voltage for transferring the toner image transferred to the intermediate transfer belt <NUM>, to the print medium P, may be applied to the transfer roller <NUM>.

The fuser <NUM> is to apply heat and/or pressure to the toner image transferred onto the print medium P, thereby fusing the print medium P. The form of the fuser <NUM> is not limited to the example illustrated in <FIG>.

According to an example as described above, the optical scanner <NUM> may form an electrostatic latent image on the photosensitive drum <NUM> by scanning the light modulated in correspondence with image information of the colors onto the photosensitive drum <NUM> of the plurality of photoconductive cartridges 3C, <NUM>, 3Y, and <NUM>. The electrostatic latent image of the photosensitive drum <NUM> of the plurality of photoconductive cartridges 3C, <NUM>, 3Y, and <NUM> is developed into a visible toner image by C, M, Y, and K toners supplied from a plurality of toner cartridges 20C, <NUM>, 20Y, and <NUM> to the plurality of development cartridges 2C, <NUM>, 2Y, and <NUM>. Each of the toner cartridges 20C, <NUM>, 20Y, and <NUM> may be respectively connected to the plurality of development cartridges 2C, <NUM>, 2Y, and <NUM> via a buffer unit <NUM> and a toner supply duct <NUM>. The developed toner images are sequentially and intermediately transferred to the intermediate transfer belt <NUM>. The print medium P loaded in a feeding unit <NUM> is transported along a feed path <NUM> to be transported between the transfer roller <NUM> and the intermediate transfer belt <NUM>. The toner image that is intermediately transferred onto the intermediate transfer belt <NUM> via the transfer bias voltage applied to the transfer roller <NUM> is transferred to the print medium P. As the print medium P passes through the fuser <NUM>, the toner image is fused on the print medium P by the heat and pressure. The fusing-completed print medium P is discharged using a discharge roller <NUM>.

The development cartridge <NUM> and the photoconductive cartridge <NUM> are consumables that may be replaced, such as when their service life is over, to address a malfunction, or the like. The development cartridge <NUM> and the photoconductive cartridge <NUM> may be individually attached/detached to/from a main body <NUM>. The development cartridge <NUM> and the photoconductive cartridge <NUM> may each slide in a first direction A1 (<FIG>) in parallel to an axial direction of the developing roller <NUM> to be attached/detached to/from the main body <NUM>. As described above, the developing roller <NUM> faces the photosensitive drum <NUM> to form a development area. In the development area, a surface of the developing roller <NUM> is arranged apart from a surface of the photosensitive drum <NUM> by about several hundreds of micrometers. In this state, when the development cartridge <NUM> or the photoconductive cartridge <NUM> is attached or detached, the photosensitive drum <NUM> may interfere with the development cartridge <NUM> and may be damaged. Considering this, the development cartridge <NUM> may be switched between a first position (indicated with a solid line in <FIG>), in which the developing roller <NUM> approaches the photosensitive drum <NUM> to form a development area, and a second position (indicated with a dotted line in <FIG>), in which the developing roller <NUM> is separated apart from the photosensitive drum <NUM> to release the development area.

<FIG> is a schematic view of a structure in which a development cartridge is switched between a first position and a second position, according to an example.

Referring to <FIG>, when the development cartridge <NUM> is mounted in the main body <NUM>, the development cartridge <NUM> is rotatably supported between a first position (indicated with a solid line) and a second position (indicated with a dotted line) with respect to a hinge axis <NUM>. The hinge axis <NUM> is parallel to the first direction A1. A position of the hinge axis <NUM> may be determined such that the development cartridge <NUM> is rotatable toward the second position by the weight of the development cartridge <NUM> itself. Alternatively, the development cartridge <NUM> may be elastically biased in a direction of the second position by an elastic member (not shown). The hinge axis <NUM> may be provided in the development cartridge <NUM> or may be provided by a bracket (not shown) that is located in the main body <NUM> to accommodate a portion (e.g., a side portion) of the development cartridge <NUM>. In this case, the bracket may be rotatably installed in the main body <NUM> to rotate with respect to the hinge axis <NUM>.

A switch lever <NUM> may be provided in the main body <NUM>. After mounting the development cartridge <NUM> in the main body <NUM>, the switch lever <NUM> may be switched to a development position (indicated with a solid line). The switch lever <NUM> may push the development cartridge <NUM> to rotate the development cartridge <NUM> with respect to the hinge axis <NUM> from the second position toward the first position. Based on the rotation of the development cartridge <NUM>, the developing roller <NUM> may approach the photosensitive drum <NUM> to form a development area.

When removing the development cartridge <NUM> or the photoconductive cartridge <NUM>, the switch lever <NUM> may be switched to a removal position (indicated with a dotted line). In that case, the development cartridge <NUM> may be rotated with respect to the hinge axis <NUM> toward the second position via its own weight or an elastic force of an elastic member (not shown). Accordingly, the developing roller <NUM> may be spaced apart from the photosensitive drum <NUM> and the development area may be released. In this state, by sliding the development cartridge <NUM> or the photoconductive cartridge <NUM> in a direction parallel to an axial direction of the developing roller <NUM>, the development cartridge <NUM> or the photoconductive cartridge <NUM> may be removed from the main body <NUM>. Because the developing roller <NUM> is spaced apart from the photosensitive drum <NUM>, damage to the photosensitive drum <NUM> during a removal process may be reduced or prevented.

A toner may be supplied from the toner cartridge <NUM> to the development cartridge <NUM>. The toner cartridge <NUM> may accommodate a toner and a carrier. The toner cartridge <NUM> is a consumable that may be replaced, such as when toner accommodated therein is used up. The toner cartridge <NUM> may be attached/detached to/from the main body <NUM>. In an image forming apparatus forming a color image, the toner cartridge <NUM> may include a plurality of toner cartridges 20C, <NUM>, 20Y, and <NUM> respectively accommodating cyan (C), magenta (M), yellow (Y), and black (K) colors to be supplied to the plurality of development cartridges 2C, <NUM>, 2Y, and <NUM>.

<FIG> is a perspective view of a connection structure between a development cartridge and a buffer unit, according to an example. <FIG> is a schematic plan view of a buffer unit, according to an example.

Referring to <FIG> and <FIG>, the toner cartridge <NUM> may be connected to the development cartridge <NUM> via the buffer unit <NUM> and a toner supply duct <NUM>. The buffer unit <NUM> may receive toner from the toner cartridge <NUM> and may supply toner to the development cartridge <NUM>. The buffer unit <NUM> may be connected to the development cartridge <NUM> via the toner supply duct <NUM>.

The buffer unit <NUM> includes an inlet portion <NUM> through which toner may be introduced from the toner cartridge <NUM>. The buffer unit <NUM> also includes a toner discharge portion <NUM> forming a discharge path to discharge toner to the development cartridge <NUM>. The toner supply duct <NUM> may be connected to the toner discharge portion <NUM>. A transporting member to transport toner introduced through the inlet portion <NUM> to the toner discharge portion <NUM> is provided in the buffer unit <NUM>. According to an example, the transporting member may include transporting members <NUM>, <NUM>, <NUM>, and <NUM> arranged from the inlet portion <NUM> to the toner discharge portion <NUM>. The toner introduced from the toner cartridge <NUM> to the buffer unit <NUM> through the inlet portion <NUM> may be transported to the toner discharge portion <NUM> via the transporting members <NUM>, <NUM>, <NUM>, and <NUM>.

The transporting member <NUM> may include a rotational shaft and spiral transport wings to transport toner in an axial direction. The transport wings may include two transport wings having opposite spiral directions to each other. As the transporting member <NUM> rotates, toner may be gathered toward a center of the transporting member <NUM> where two transport wings are connected and pushed to be transported toward the transporting member <NUM>. The transporting member <NUM> may stir the toner in the buffer unit <NUM> to prevent the toner from agglomerating. The transporting member <NUM> may transport the toner in the buffer unit <NUM> in a radial direction. To this end, the transporting member <NUM> may include a rotational shaft and paddle-type transport wings extending from the rotational shaft in a radial direction. The transport member <NUM> may discharge toner through the toner discharge portion <NUM>. The transport member <NUM> may include an auger including a rotational shaft and spiral wings to transport toner in an axial direction. The transport member <NUM> may extend into the toner discharge portion <NUM>. The number and shape of the transporting members are not limited to the example illustrated in <FIG>.

A driving motor <NUM> to drive the transporting members <NUM>, <NUM>, <NUM>, and <NUM> may be provided in the buffer unit <NUM>. The driving motor <NUM> may be connected to the transporting members <NUM>, <NUM>, <NUM>, and <NUM> via a power connection structure such as a gear train <NUM>. Although not illustrated in the drawings, the buffer unit <NUM> may include a toner remaining amount sensor. As an example, the toner remaining amount sensor may detect a toner level in the buffer unit <NUM>.

The buffer unit <NUM> may be connected to the development cartridge <NUM> via the toner supply duct <NUM>. Referring to <FIG>, a toner inlet portion <NUM> is provided in the development cartridge <NUM>. The toner inlet portion <NUM> may protrude from a side wall <NUM> of the development cartridge <NUM> in the first direction A1. The toner inlet portion <NUM> may be in a cylinder form. An opening <NUM> through which toner may be introduced into the development cartridge <NUM> is provided in the toner inlet portion <NUM>.

The toner supply duct <NUM> may include a first connecting portion <NUM> to connect to the toner discharge portion <NUM>, a second connecting portion <NUM> to connect to the toner inlet portion <NUM>, and a connection tube <NUM> to connect the first connecting portion <NUM> to the second connecting portion <NUM>. In an example, the connection tube <NUM> may be formed of an elastic material, such as rubber.

As described above, the development cartridge <NUM> may be rotated with respect to the hinge axis <NUM> to be rotated between the first position and the second position. The hinge axis <NUM>, which is a center of rotation of the development cartridge <NUM>, extends in the first direction A1 and is positioned between the developing roller <NUM> and the toner inlet portion <NUM>. That is, with respect to the hinge axis <NUM>, the developing roller <NUM> is located above the hinge axis <NUM>, and the toner inlet portion <NUM> is located below the hinge axis <NUM>. When the development cartridge <NUM> is rotated toward the second position, the toner inlet portion <NUM> is drawn toward the buffer unit <NUM>. As the toner supply duct <NUM> is between the buffer unit <NUM> and the development cartridge <NUM>, a repulsive force disturbing rotation of the development cartridge <NUM> toward the second position may be generated by the toner supply duct <NUM>. Even when the connection tube <NUM> is formed of an elastic material, when a repulsive force due to the elasticity of the connection tube <NUM> is greater than a rotational force of the development cartridge <NUM> by its own weight, the development cartridge <NUM> may not be rotated to the second position. In that case, the development area may not be properly released and interference with the development cartridge <NUM> may occur when attaching or detaching the photoconductive cartridge <NUM>. In addition, when the weight of the development cartridge <NUM> itself or the elasticity of the elastic member are sufficiently greater than the repulsive force of the connection tube <NUM>, the connection tube <NUM> may be deformed, such as by bending. In that case, toner supply through the connection tube <NUM> may be impeded.

In an example, the toner supply duct <NUM> may be connected to the toner discharge portion <NUM> to pivot in a direction allowing rotation of the development cartridge <NUM> between the first position and the second position.

According to an example, the toner discharge portion <NUM> extends from a side wall <NUM> of the buffer unit <NUM> in a second direction A2. The second direction A2 is a direction orthogonal to the first direction A1, which is parallel to an axial direction of the developing roller <NUM>. To allow rotation of the development cartridge <NUM> between the first position and the second position, the first connecting portion <NUM> may be connected to the toner discharge portion <NUM> to be pivoted relative to a first axis B1 parallel to the first direction A1.

<FIG> is a disassembled perspective view of a connection structure between a toner discharge portion and a first connecting portion, according to an example. <FIG> is a side view of <FIG> taken in a first direction, according to an example.

Referring to <FIG> and <FIG>, the toner discharge portion <NUM> may be in the form of a hollow cylinder extending from the side wall <NUM> in the second direction A2. The toner discharge portion <NUM> may be inserted into the first connecting portion <NUM>. The first connecting portion <NUM> may be in the form of a hollow cylinder into which the toner discharge portion <NUM> may be inserted. A hinge protrusion <NUM> protruding along the first axis B1 is provided on the toner discharge portion <NUM>. A hinge hole <NUM> into which the hinge protrusion <NUM> may be inserted is provided in the first connecting portion <NUM>. As the hinge protrusion <NUM> is inserted into the hinge hole <NUM>, the first connecting portion <NUM> is connected to the toner discharge portion <NUM> to be pivotable relative to the first axis B1.

An inner diameter of the first connecting portion <NUM> is greater than an outer diameter of the toner discharge portion <NUM>. Accordingly, the first connecting portion <NUM> may be pivoted with respect to the toner discharge portion <NUM> around the hinge protrusion <NUM> to some extent. An end portion <NUM> of the toner discharge portion <NUM> opposite the side wall <NUM>, that is, in the second direction A2, has a shape allowing the first connecting portion <NUM> to downwardly pivot with respect to the first axis B1. For example, the end portion <NUM> has a lower end portion <NUM>-<NUM> and an upper end portion <NUM>-<NUM> that is concave with respect to the lower end portion <NUM>-<NUM> in the second direction A2. That is, the lower end portion <NUM>-<NUM> protrudes further from the upper end portion <NUM>-<NUM> in the second direction A2. Although not illustrated in the drawings, the end portion <NUM> of the toner discharge portion <NUM> may be downwardly inclined from the upper end portion <NUM>-<NUM> toward the lower end portion <NUM>-<NUM>.

According to this configuration, the inner diameter of the first connecting portion <NUM> may be reduced and a pivot angle of the first connecting portion <NUM> with respect to the hinge protrusion <NUM> may be increased at the same time. In addition, in order for the development cartridge <NUM> to stably rotate between the first position and the second position, the toner supply duct <NUM> may be downwardly pivoted relative to the first axis B1. By shaping the end portion <NUM> of the toner discharge portion <NUM> such that the lower end portion <NUM>-<NUM> protrudes further than the upper end portion <NUM>-<NUM> in the second direction A2, the inner diameter of the first connecting portion <NUM> may be minimized and a downward pivot angle of the toner supply duct <NUM> may be increased at the same time.

The image forming apparatus may include a restriction member restricting the pivot angle of the first connecting portion <NUM> with respect to the first axis B1. An example of a restriction member restricting a pivot angle of the first connecting portion <NUM> relative to the first axis B1 is provided below with reference to <FIG> and <FIG>.

<FIG> is a cross-sectional view illustrating a restriction member restricting a downward pivot angle of a first connecting portion with respect to a first axis, according to an example. <FIG> is a cross-sectional view illustrating a restriction member restricting an upward pivot angle of a first connecting portion with respect to a first axis, according to an example.

Referring to <FIG> and <FIG>, while the development cartridge <NUM> is mounted in the main body <NUM>, when the switch lever <NUM> is rotated from the position indicated with the solid line in <FIG> toward the position indicated with the dotted line in <FIG>, the development cartridge <NUM> is rotated from the first position (indicated with the solid line in <FIG>) toward the second position (indicated with the dotted line in <FIG>) by its own weight or by an elastic force of an elastic member. In that case, the toner inlet portion <NUM> is moved in a direction away from the buffer unit <NUM>. In order to prevent a repulsive force caused by the toner supply duct <NUM> and disturbing rotation of the development cartridge <NUM> toward the second position, the first connecting portion <NUM> may be downwardly pivoted with respect to the hinge protrusion <NUM> in the state illustrated in <FIG>. For example, as the inner diameter of the first connecting portion <NUM> is greater than the outer diameter of the toner discharge portion <NUM>, and the upper end portion <NUM>-<NUM> of the toner discharge portion <NUM> is concave in the second direction A2 compared to the lower end portion <NUM>-<NUM>, the first connecting portion <NUM> may be downwardly pivoted with respect to the hinge protrusion <NUM>.

As illustrated in <FIG>, as the downward pivot angle is increased such that the upper end portion <NUM>-<NUM> of the toner discharge portion <NUM> contacts an inner wall <NUM> of the first connecting portion <NUM>, the first connecting portion <NUM> may no longer be downwardly pivoted. Accordingly, the upper end portion <NUM>-<NUM> of the toner discharge portion <NUM> may act as a restriction member restricting a downward pivot angle of the first connecting portion <NUM> by contacting the inner wall <NUM> of the first connecting portion <NUM> when the first connecting portion <NUM> is downwardly pivoted. The restricted downward pivot angle may be equal to or greater than a pivot angle of the first connecting portion <NUM> when the development cartridge <NUM> has reached the second position.

While the development cartridge <NUM> is mounted in the main body <NUM>, when the switch lever <NUM> is rotated from the position indicated with the dotted line in <FIG> to the position indicated with the solid line in <FIG>, the development cartridge <NUM> is pushed by the switch lever <NUM> to be rotated from the second position (indicated with the dotted line in <FIG>) to the first position (indicated with the solid line in <FIG>). The toner inlet portion <NUM> is moved in a direction to approach the buffer unit <NUM>. As the development cartridge <NUM> is rotated from the second position toward the first position, the toner supply duct <NUM> starts upwardly pivoting with respect to the hinge protrusion <NUM> from the state illustrated in <FIG>.

A restriction protrusion may be provided in one of the side wall <NUM> of the buffer unit <NUM>, from which the toner discharge portion <NUM> extends, and an end portion <NUM> of the first connecting portion <NUM> facing the side wall <NUM>. The restriction protrusion may be provided to face the other one of the side wall <NUM> and the end portion <NUM> of the first connecting portion <NUM>. The restriction protrusion may be implemented by, for example, a rib <NUM> protruding from the side wall <NUM> of the buffer unit <NUM>. When the first connecting portion <NUM> is upwardly pivoted, the end portion <NUM> of the first connecting portion <NUM> contacts the rib <NUM>. In that case, the first connecting portion <NUM> may no longer be upwardly pivoted. Accordingly, the rib <NUM> may act as a restriction member restricting an upward pivot angle of the first connecting portion <NUM>. The restricted upward pivot angle may be equal to or greater than a pivot angle of the first connecting portion <NUM> when the development cartridge <NUM> has reached the first position.

According to this configuration, the upward and downward pivot angles of the first connecting portion <NUM> with respect to the first axis B1 may be restricted.

Referring back to <FIG>, the toner inlet portion <NUM> is located on the side wall <NUM> of the development cartridge <NUM> in the first direction A1, and the second connecting portion <NUM> of the toner supply duct <NUM> may be connected to the toner inlet portion <NUM>. The development cartridge <NUM> slides in the first direction A1 to be attached/detached to/from the main body <NUM>. Accordingly, before removing the development cartridge <NUM> from the main body <NUM>, the second connecting portion <NUM> may be separated from the toner inlet portion <NUM>, and after the development cartridge <NUM> is mounted in the main body <NUM>, the second connecting portion <NUM> may be connected to the toner inlet portion <NUM>. In addition, after the second connecting portion <NUM> is separated from the toner inlet portion <NUM>, the toner supply duct <NUM> should be located at a position that does not interfere with the development cartridge <NUM> sliding in the first direction A1.

Considering the above, the first connecting portion <NUM> may be connected to the toner discharge portion <NUM> to be pivotable with respect to a second axis B2, which is an axis in the second direction A2. In addition, the second connecting portion <NUM> may be attachably/detachably connected to/from the toner inlet portion <NUM> in the first direction A1. According to an example, as illustrated in <FIG> and <FIG>, the hinge hole <NUM> may have an arc shape with respect to the second axis B2. According to the configuration, the first connecting portion <NUM> may be pivotably connected to the toner discharge portion <NUM> with respect to the second axis B2. As pivoting of the first connecting portion <NUM> with respect to the first axis B1 and the second axis B2 is possible by the hinge hole <NUM> and the hinge protrusion <NUM>, a two-axis pivot connection between the toner supply duct <NUM> and the buffer unit <NUM> is possible via a simple connection structure.

A downward pivot angle and an upward pivot angle of the first connecting portion <NUM> with respect to the second axis B2 may be restricted by a first end portion <NUM> and a second end portion <NUM> of the hinge hole <NUM>. That is, when the first connecting portion <NUM> is downwardly pivoted with respect to the second axis B2, when the hinge protrusion <NUM> contacts the first end portion <NUM> of the hinge hole <NUM>, the first connecting portion <NUM> is no longer downwardly pivoted. Also, when the first connecting portion <NUM> is upwardly pivoted with respect to the second axis B2, when the hinge protrusion <NUM> contacts the second end portion <NUM> of the hinge hole <NUM>, the first connecting portion <NUM> is no longer upwardly pivoted. A position of the first end portion <NUM> of the hinge hole <NUM> may be determined such that the second connecting portion <NUM> of the toner supply duct <NUM> may be naturally connected to the toner inlet portion <NUM> of the development cartridge <NUM>. A position of the second end portion <NUM> of the hinge hole <NUM> may be determined such that the toner supply duct <NUM> is sufficiently upwardly pivoted to a position where the toner supply duct <NUM> does not interfere with the development cartridge <NUM> that is being attached or detached.

<FIG> is a schematic side view taken in a second direction and illustrating a state in which a second connecting portion is connected to a toner inlet portion of a development cartridge, according to an example. <FIG> is a schematic side view taken in a second direction and illustrating a state in which a second connecting portion is released from a toner inlet portion of a development cartridge, according to an example.

An example process of mounting the development cartridge <NUM> and the photoconductive cartridge <NUM> in the main body <NUM> will be described with reference to <FIG>.

The photoconductive cartridge <NUM> may be first mounted in the main body <NUM>, or the development cartridge <NUM> may be first mounted in the main body <NUM> and then the photoconductive cartridge <NUM> may be mounted in the main body <NUM>. Hereinafter, an example process of mounting the development cartridge <NUM> first in the main body <NUM> and then mounting the photoconductive cartridge <NUM> in the main body <NUM> will be described.

As illustrated in <FIG>, while the toner supply duct <NUM> is upwardly pivoted with respect to the second axis B2, the development cartridge <NUM> may slide in the first direction A1 to mount the development cartridge <NUM> in the main body <NUM>. As illustrated in <FIG>, the toner supply duct <NUM> is downwardly pivoted with respect to the second axis B2 to connect the second connecting portion <NUM> to the toner inlet portion <NUM> of the development cartridge <NUM>. The switch lever <NUM> is located at a position indicated with the dotted line in <FIG>. The development cartridge <NUM> is located at the second position where the development area is released (indicated with the dotted line in <FIG>).

In this state, the photoconductive cartridge <NUM> may slide in the first direction A1 to be mounted in the main body <NUM>. The first connecting portion <NUM> of the toner supply duct <NUM> is pivotably connected to the toner discharge portion <NUM> with respect to the first axis B1. When the second connecting portion <NUM> is connected to the toner inlet portion <NUM>, as illustrated in <FIG>, the toner supply duct <NUM> is naturally located at a position downwardly pivoted with respect to the first axis B1. The development cartridge <NUM> may be maintained in the second position. Accordingly, during a process in which the photoconductive cartridge <NUM> is mounted, interference between the development cartridge <NUM> and the photosensitive drum <NUM> is reduced or avoided.

When the photoconductive cartridge <NUM> is completely mounted, the switch lever <NUM> is rotated to the position indicated with the solid line in <FIG>. In that case, the development cartridge <NUM> is rotated with respect to the hinge axis <NUM> to be switched to the first position where a development area is formed. Here, the toner inlet portion <NUM> is moved in a direction to draw near to the buffer unit <NUM>, and as illustrated in <FIG>, the toner supply duct <NUM> is upwardly pivoted with respect to the first axis B1. Accordingly, a stable connection between the toner supply duct <NUM> and the toner inlet portion <NUM> may be maintained, and the development cartridge <NUM> may be rotated stably to the first position.

The photoconductive cartridge <NUM> may also be mounted in the main body <NUM> after mounting the development cartridge <NUM> and maintaining the toner supply duct <NUM> in an upwardly pivoted position illustrated in <FIG>. In that case, by downwardly pivoting the toner supply duct <NUM> as illustrated in <FIG>, the second connecting portion <NUM> may be connected to the toner inlet portion <NUM>. By rotating the switch lever <NUM> to the position indicated with the solid line in <FIG>, the development cartridge <NUM> may be switched to the first position.

An example process of removing the development cartridge <NUM> and the photoconductive cartridge <NUM> from the main body <NUM> will be described with reference to <FIG>.

When removing the development cartridge <NUM> first, the second connecting portion <NUM> is separated from the toner inlet portion <NUM>, and the toner supply duct <NUM> is upwardly pivoted with respect to the second axis B2 as illustrated in <FIG>. The switch lever <NUM> is rotated from the position indicated with the solid line in <FIG> toward the position indicated with the dotted line in <FIG>. The development cartridge <NUM> is rotated with respect to the hinge axis <NUM> via its own weight or an elastic force of an elastic member (not shown) to be switched between the first position and the second position. In this state, the development cartridge <NUM> may be removed from the main body <NUM>.

When removing the photoconductive cartridge <NUM> first, the development cartridge <NUM> is switched between the first position and the second position before removing the photoconductive cartridge <NUM>. The switch lever <NUM> is rotated from the position indicated with the solid line in <FIG> to the position indicated with the dotted line in <FIG>. The development cartridge <NUM> is rotated with respect to the hinge axis <NUM> via its own weight or an elastic force of an elastic member (not shown) to be switched between the first position and the second position. Here, the toner inlet portion <NUM> is moved in a direction away from the buffer unit <NUM>, and as illustrated in <FIG>, the toner supply duct <NUM> is downwardly pivoted with respect to the first axis B1. Accordingly, the development cartridge <NUM> may be stably rotated toward the second position. When the development cartridge <NUM> is located in the second position, the development area is released. In this state, the photoconductive cartridge <NUM> may be removed from the main body <NUM>. As the development cartridge <NUM> may be stably maintained in the second position, while the photoconductive cartridge <NUM> is being removed, interference between the development cartridge <NUM> and the photosensitive drum <NUM> is not generated.

Next, the development cartridge <NUM> may be removed. First, the second connecting portion <NUM> is separated from the toner inlet portion <NUM>, and the toner supply duct <NUM> is upwardly pivoted with respect to the second axis B2 as illustrated in <FIG>. Next, the development cartridge <NUM> may slide to be removed from the main body <NUM>.

Claim 1:
An image forming apparatus comprising:
a toner cartridge (<NUM>);
a photoconductive cartridge (<NUM>) comprising a photosensitive drum (<NUM>);
a development cartridge (<NUM>) comprising:
a toner inlet portion (<NUM>); and
a developing roller (<NUM>);
a buffer unit (<NUM>) to receive toner from the toner cartridge (<NUM>) and to supply the toner to the development cartridge (<NUM>), the buffer unit (<NUM>) comprising a toner discharge portion (<NUM>) extending in a second direction (A2) orthogonal to a first direction (A1) which is an axial direction of the developing roller (<NUM>), and forming a discharge path of the toner; and
a toner supply duct (<NUM>) comprising a first connecting portion (<NUM>) pivotably connected to the toner discharge portion (<NUM>) to be pivoted relative to a first axis (B1) parallel to the first direction (A1), a second connecting portion (<NUM>) connected to the toner inlet portion (<NUM>), and a connection tube (<NUM>) connecting the first connecting portion (<NUM>) to the second connecting portion (<NUM>).