Patent Description:
Conventionally, there has been known an electro-photographic type image forming apparatus such as a laser printer and an LED printer. The image forming apparatus includes a developing cartridge. The developing cartridge includes a developing roller for supplying developing agent. A conventional image forming apparatus is described in <CIT> or <CIT>, for example. The image forming apparatus described in <CIT> or <CIT> includes a drum cartridge including a photosensitive drum. The developing cartridge is attachable to the drum cartridge. Upon attachment of the developing cartridge to the drum cartridge, the photosensitive drum and the developing roller are brought into contact with each other.

The image forming apparatus disclosed in <CIT> is switchable between a state where the developing roller and the photosensitive drum are in contact with each other and a state where the developing roller and the photosensitive drum are separated from each other. In the image forming apparatus disclosed in <CIT>, components for moving the developing cartridge to separate the developing roller from the photosensitive drum are provided at each side of a drum unit. The components at each side need to receive a driving force from a main body of the image forming apparatus.

In view of the foregoing, it is an object of the present disclosure to provide a developing cartridge capable of moving a developing roller away from a photosensitive drum due to a driving force applied to only one side without necessitating application of a driving force to both sides.

(First Aspect) In order to attain the above and other objects, according to a first aspect of the present disclosure, there is provided a developing cartridge including: a casing; a developing roller; a first cam; a second cam; and a connection member. The casing is configured to accommodate developing agent therein. The casing includes one end portion and another end portion spaced apart from the one end portion in a first direction. The developing roller is rotatable about a developing roller axis extending in the first direction. The first cam is positioned at the one end portion of the casing. The first cam is movable relative to the casing and the developing roller in the first direction between a first position and a second position. The first cam in the second position is positioned closer to the another end portion of the casing in the first direction than the first cam in the first position is to the another end portion of the casing. The second cam is positioned at the another end portion of the casing. The second cam is movable relative to the casing and the developing roller in the first direction between a third position and a fourth position. The second cam in the fourth position is positioned closer to the another end portion of the casing in the first direction than the second cam in the third position is to the another end portion of the casing. The connection member connects the first cam and the second cam to each other. The second cam is movable from the third position to the fourth position due to a tensile force of the connection member in accordance with movement of the first cam from the first position to the second position.

(Second Aspect) In the developing cartridge according to the first aspect of the present disclosure, it is preferable that: the first cam has a first end and a second end, the second end being positioned closer to the another end portion of the casing in the first direction than the first end is to the another end portion of the casing; the second cam has a third end and a fourth end, the fourth end being positioned closer to the another end portion of the casing in the first direction than the third end is to the another end portion of the casing; and the connection member connects the first end of the first cam and the fourth end of the second cam to each other.

(Third Aspect) In the developing cartridge according to the first or second aspect of the present disclosure, preferably, the developing roller has an outer circumferential surface including one end portion and another end portion in a second direction crossing the first direction, the one end portion of the outer circumferential surface of the developing roller being exposed to an outside of the casing, the another end portion of the outer circumferential surface of the developing roller being positioned inside the casing.

(Fourth Aspect) In the developing cartridge according to the third aspect of the present disclosure, it is preferable that: the casing has one outer surface and another outer surface, the one outer surface being positioned at one end portion in the second direction of the casing, the another outer surface being positioned at another end portion in the second direction of the casing; the first cam and the second cam are positioned at the one outer surface; and the connection member has at least a portion extending in the first direction along the another outer surface.

(Fifth Aspect) In the developing cartridge according to the fourth aspect of the present disclosure, it is preferable that: the casing further has a groove positioned at the another outer surface and extending in the first direction; and the connection member has at least a portion positioned within the groove.

(Sixth Aspect) In the developing cartridge according to the third aspect of the present disclosure, it is preferable that: the casing has one outer surface and another outer surface, the one outer surface being positioned at one end portion in the second direction of the casing, the another outer surface being different from the one outer surface; the first cam and the second cam are positioned at the one outer surface; and the connection member has at least a portion extending in the first direction along the another outer surface.

(Seventh Aspect) In the developing cartridge according to any one of the first to sixth aspects of the present disclosure, it is preferable that: the first cam has a first inclined surface inclined relative to the first direction so as to be distant from the casing as extending from the another end portion to the one end portion of the casing; and the second cam has a second inclined surface inclined relative to the first direction so as to be distant from the casing as extending from the another end portion to the one end portion of the casing.

(Eighth Aspect) In the developing cartridge according to any one of the third to seventh aspects of the present disclosure, it is preferable that: the first cam is movable in the second direction together with the casing and the developing roller; and the second cam is movable in the second direction together with the casing and the developing roller.

(Ninth Aspect) In the developing cartridge according to any one of the third to eighth aspects of the present disclosure, it is preferable that: the developing cartridge is for use with a drum cartridge including a photosensitive drum; and in a state where the developing cartridge is attached to the drum cartridge, the first cam is movable in the second direction relative to the photosensitive drum together with the casing and the developing roller, and the second cam is movable in the second direction relative to the photosensitive drum together with the casing and the developing roller.

(Tenth Aspect) In the developing cartridge according to the seventh aspect depending on any one of the third to sixth aspects of the present disclosure, it is preferable that: the first inclined surface gradually approaches the casing in the second direction as extending from the one end portion to the another end portion in the first direction of the casing; and the second inclined surface gradually approaches the casing in the second direction as extending from the one end portion to the another end portion in the first direction of the casing.

(Eleventh Aspect) In the developing cartridge according to any one of the first to tenth aspects of the present disclosure, preferably, the connection member is a flexible member.

(Twelfth Aspect) In the developing cartridge according to any one of the first to eleventh aspects of the present disclosure, preferably, the connection member has a portion extending in the first direction and another portion extending in a direction crossing the first direction.

(Thirteenth Aspect) In the developing cartridge according to the eleventh or twelfth aspect of the present disclosure, preferably, the connection member is one of a sheet-like member and a wire member.

(Fourteenth Aspect) Preferably, the developing cartridge according to any one of the first to thirteenth aspects of the present disclosure further includes an elastic member urging the second cam in a direction from the fourth position toward the third position.

(Fifteenth Aspect) In the developing cartridge according to the fourteenth aspect of the present disclosure, preferably, the elastic member is a spring.

(Sixteenth Aspect) In the developing cartridge according to the fifteenth aspect of the present disclosure, preferably, the spring is a coil spring.

(Seventeenth Aspect) In the developing cartridge according to any one of the fourth to sixteenth aspects of the present disclosure, preferably, the casing has a first guide groove and a second guide groove positioned at the one outer surface, the first guide groove guiding movement of the first cam between the first position and the second position, the second guide groove guiding movement of the second cam between the third position and the fourth position.

(Eighteenth Aspect) In the developing cartridge according to the seventeenth aspect of the present disclosure, preferably, the casing includes a frame having a flat plate shape and positioned at the one outer surface, the frame having the first guide groove and the second guide groove.

(Nineteenth Aspect) In the developing cartridge according to the seventeenth or eighteenth aspect of the present disclosure, preferably, at least one of the first cam and the second cam includes a retainer for preventing the at least one of the first cam and the second cam from disengaging from corresponding one of the first guide groove and the second guide groove.

(Twentieth Aspect) In the developing cartridge according to any one of the first to nineteenth aspects of the present disclosure, preferably, the connection member is made from resin.

(Twenty-First Aspect) In the developing cartridge according to the ninth aspect of the present disclosure, preferably, in the state where the developing cartridge is attached to the drum cartridge, the developing roller is in contact with the photosensitive drum in the first position of the first cam and in the third position of the second cam, and the developing roller is separated from the photosensitive drum in the second position of the first cam and at the fourth position of the second cam.

(Twenty-Second Aspect) In the developing cartridge according to the second aspect of the present disclosure, it is preferable that: the first end of the first cam has a pressure contact surface for receiving a pressing force; and when the pressure contact surface receives the pressing force, the first cam moves from the first position to the second position.

(Twenty-Third Aspect) In the developing cartridge according to the twenty-second aspect of the present disclosure, preferably, the developing cartridge is for use with a drum cartridge, the drum cartridge being attachable to a main body portion of an image forming apparatus in a state where the developing cartridge is attached to the drum cartridge, the main body portion including a drive shaft extending in the first direction, the drive shaft being movable in the first direction between an advanced position and a retracted position in response to receiving a driving force applied from the main body portion, the drive shaft being configured to press the pressure contact surface by the movement of the drive shaft toward the advanced position which is a direction from the one end portion to the another end portion of the casing in the first direction.

(Twenty-Fourth Aspect) In the developing cartridge according to any one of the third to twenty-third aspects of the present disclosure, it is preferable that: the casing has one end portion in a third direction crossing the first direction and the second direction; and the developing roller is positioned at the one end portion in the third direction of the casing.

(Twenty-Fifth Aspect) In the developing cartridge according to the twenty-fourth aspect of the present disclosure, preferably, the casing further has an outer surface positioned at another end portion in the third direction of the casing. It is also preferable that the developing cartridge further includes a handle configured to be gripped by a user, the handle being positioned at the outer surface.

(Twenty-Sixth Aspect) In the developing cartridge according to to the seventh aspect of the present disclosure, it is preferable that: the drum cartridge has a first contact surface and a second contact surface, the drum cartridge being attachable to a main body portion of an image forming apparatus in a state where the developing cartridge is attached to the drum cartridge; and in the state where the developing cartridge is attached to the drum cartridge, the first contact surface is in contact with the first inclined surface, and the second contact surface is in contact with the second inclined surface.

(Twenty-Seventh Aspect) In the developing cartridge according to the twenty-sixth aspect of the present disclosure, it is preferable that: the first contact surface is at least a portion of an outer circumferential surface of a first cylinder centered on a first rotational axis extending in a third direction crossing the first direction; and the second contact surface is a at least a portion of an outer circumferential surface of a second cylinder centered on a second rotational axis extending in the third direction.

(Twenty-Eighth Aspect) In the developing cartridge according to the twenty-seventh aspect of the present disclosure, it is preferable that: the first cylinder is rotatable about the first rotational axis; and the second cylinder is rotatable about the second rotational axis.

According to the first to twenty-eighth aspects of the present disclosure, the developing roller is movable in a direction crossing the first direction due to a driving force applied to only one side in the developing cartridge.

According to the first aspect of the present disclosure, the second cam moves from the third position toward the fourth position due to a tensile force of the connection member in accordance with movement of the first cam from the first position toward the second position. During this movement, the first cam and the second cam are pressed by other components, whereby the developing roller and the casing move in a direction crossing the first direction.

According to the second aspect of the present disclosure, the second end of the first cam and the third end of the second cam face each other in the first direction. The first end of the first cam is an end of the first cam opposite to the second end (i.e., the outer end). Further, the fourth end of the second cam is an end of the second cam opposite to the third end (i.e., the outer end). That is, the connection member connects the outer ends of the first cam and the second cam (i.e., the first end and the fourth end) to each other. With this configuration, a tensile force can be generated favorably in the connection member.

According to the fourth aspect of the present disclosure, a sufficient length from the one end to the other end of the connection member can be obtained, and at least two bending portions can be provided in the connection member. As a result, a tensile force can be generated in the connection member with high accuracy.

According to the fifth aspect of the present disclosure, deviation in position of an intermediate portion of the connection member (i.e., a portion of the connection member between the one end and the other end) in a third direction crossing the second direction can be restrained.

According to the sixth aspect of the present disclosure, a sufficient length from the one end to the other end of the connection member can be obtained, and bending portions can be provided in the connection member. As a result, a tensile force can be generated in the connection member with high accuracy.

According to the seventh aspect of the present disclosure, the first inclined surface of the first cam and the second inclined surface of the second cam are accurately pressed by other components, whereby the developing roller and the casing can move in a direction crossing the first direction.

According to the eleventh aspect of the present disclosure, a tensile force can be generated in the connection member with high accuracy.

According to the fourteenth aspect of the present disclosure, when a tensile force of the connection member decreases after the second cam is pulled from the third position to the fourth position due to the tensile force of the connection member, the second cam can move back from the fourth position to the third position owing to the urging force of the elastic member. As a result, the developing roller once moved in a direction crossing the first direction can be easily returned to its original position.

According to the nineteenth aspect of the present disclosure, when the first cam and the second come are applied with a tensile force by the connection member, the first cam and the second cam can be prevented from disengaging from the first guide groove and the second guide groove, respectively.

According to the twenty-second aspect of the present disclosure, when a pressing force is applied to the pressure contact surface of the first cam, the first cam can move from the first position to the second position. At the same time, the second cam can move from the third position to the fourth position.

According to the twenty-third aspect of the present disclosure, the developing roller can move in a direction crossing the first direction together with the casing due to a driving force supplied from the main body portion.

According to the twenty-sixth aspect of the present disclosure, the first cam and the second cam moves in the first direction from one side toward another side in a state where the first inclined surface and the second inclined surface are in contact with other components. By this contact, the first inclined surface is pressed by the first contact surface of the other components, and the second inclined surface is pressed by the second contact surface of the other components, whereby the developing roller can move in a direction crossing the first direction together with the casing.

According to the twenty-eighth aspect of the present disclosure, a frictional force generated between the first inclined surface and the first contact surface , and a frictional force generated between the second inclined surface and the second contact surface can be reduced in a case where the first cam and the second cam move in the first direction toward from the one side toward the other side in a state where the first inclined surface is in contact with the first contact surface and the second inclined surface is in contact with the second contact surface.

Hereinafter, one embodiment of the present disclosure will be described while referring to the accompanying drawings.

In the following description, a direction in which a rotational axis of a developing roller (a developing roller-axis) will be referred to as "first direction". Here, an outer circumferential surface of the developing roller includes a portion exposed to an outside of a casing, and another portion positioned inside the casing. A direction in which the portion of the circumferential surface of the developing roller and the other portion of the circumferential surface of the developing roller are arrayed will be referred to as "second direction". The first direction and the second direction cross each other. Preferably, the first direction and the second direction are perpendicular to each other. Further, a direction crossing both the first direction and the second direction will be referred to as "third direction". Preferably, the third direction is perpendicular to both the first direction and the second direction.

<FIG> is a schematic diagram of an image forming apparatus <NUM>. The image forming apparatus <NUM> is an electro-photographic type printer such as a laser printer and an LED printer. As illustrated in <FIG>, the image forming apparatus <NUM> includes four developing cartridges <NUM>, a drum cartridge <NUM>, and a main body portion <NUM>.

Hereinafter, an overall configuration of the main body portion <NUM> will be described. The main body portion <NUM> includes a main frame <NUM>, a transfer belt (not illustrated), and a controller <NUM>.

The main frame <NUM> has a generally rectangular-parallelepiped shape, and has an internal space. The drum cartridge <NUM> to which the developing cartridges <NUM> are attached can be accommodated in the internal space of the main frame <NUM>. Further, four chargers (not illustrated), four light sources (not illustrated), the transfer belt, and the controller <NUM> are provided in the main frame <NUM>.

The transfer belt is an endless belt for conveying printing sheets. The transfer belt is positioned opposite to developing rollers <NUM> with respect to photosensitive drums <NUM> of the drum cartridge <NUM> in a state where the drum cartridge <NUM> to which the developing cartridges <NUM> are attached is positioned in the internal space of the main frame <NUM>. The transfer belt has an outer peripheral surface capable of contacting outer circumferential surfaces of the photosensitive drums <NUM>.

The controller <NUM> includes a processor such as CPU, and a main body memory. The main body memory is a storage medium from which information is readable and to which information is writable. For example, the main body memory is a flash ROM or an EEPROM. The memory stores therein computer programs for controlling operations performed in the image forming apparatus <NUM>. The processor is configured to execute various processing in accordance with the computer programs stored in the memory. That is, the processor is configured to execute various printing process and other processes associated therewith to be performed in the image forming apparatus <NUM>.

Next, an overall configuration of the drum cartridge <NUM> will be described. <FIG> is a view of the drum cartridge <NUM> to which the developing cartridges <NUM> are attached as viewed in the third direction from another side toward one side. As illustrated in <FIG> and <FIG>, the drum cartridge <NUM> includes the four photosensitive drums <NUM>, and a frame <NUM>.

Each of the four photosensitive drums <NUM> illustrated in <FIG> has an outer circumferential surface having a cylindrical shape centered on a drum axis, which is a rotational axis extending in the first direction. The outer circumferential surface of each photosensitive drum <NUM> is coated with photosensitive material. Each of the photosensitive drums <NUM> is rotatable about its drum axis.

The frame <NUM> is a frame that supports the four photosensitive drums <NUM> such that the four photosensitive drums <NUM> are arranged to be spaced from one another in the second direction. The frame <NUM> includes a pair of side frames <NUM> and <NUM> facing each other in the first direction. The photosensitive drums <NUM> are rotatably supported by the side frames <NUM> and <NUM>.

Hereinafter, overall configurations of the developing cartridges <NUM> will be described. <FIG> are perspective views of the developing cartridge <NUM>.

As illustrated in <FIG> and <FIG>, the developing cartridges <NUM> are attachable to and detachable from the frame <NUM> of the drum cartridge <NUM>. As illustrated in <FIG>, each of the developing cartridges <NUM> includes a casing <NUM> configured to accommodate developing agent therein. The casing <NUM> includes a container 10A and a lid 10B (an example of a frame). The container 10A has an internal space. The lid 10B has a flat plate shape. The lid 10B is positioned at one end portion in the second direction of the casing <NUM> to cover an opening formed at one end portion in the second direction of the container 10A. Further, the lid 10B has a third outer surface <NUM> (described later). In the meantime, the container 10A further has an opening portion 10C at one end portion in the third direction thereof. The developing roller <NUM> (described later) is positioned in the opening portion 10C.

The casing <NUM> has one end portion <NUM>, and another end portion <NUM> spaced apart from the one end portion <NUM> in the first direction. A first outer surface <NUM> is positioned at the one end portion <NUM> of the casing <NUM>, and a second outer surface <NUM> is positioned at the other end portion <NUM> of the casing <NUM>. That is, the first outer surface <NUM> is positioned at one end portion in the first direction of the casing <NUM>, while the second outer surface <NUM> is positioned at another end portion in the first direction of the casing <NUM>. The casing <NUM> further has the third outer surface <NUM> and a fourth outer surface <NUM> (see <FIG>) spaced apart from each other in the second direction. The third outer surface <NUM> is positioned at one end portion in the second direction of the casing <NUM>. The fourth outer surface <NUM> is positioned at another end portion in the second direction of the casing <NUM>.

The four developing cartridges <NUM> accommodate therein toners of colors different from one another (for example, cyan, magenta, yellow and black). However, the developing cartridges <NUM> may accommodate therein toner of the same color.

Each of the developing cartridges <NUM> includes the developing roller <NUM> having a cylindrical shape. The developing roller <NUM> is rotatable about a developing roller-axis which is a rotational axis extending in the first direction. The developing roller <NUM> is supported by the casing <NUM> so as to be rotatable about the developing roller-axis.

The developing roller <NUM> includes a developing roller body <NUM> and a developing roller shaft <NUM>. The developing roller body <NUM> has a hollow cylindrical shape and extends in the first direction. The developing roller body <NUM> is made of material having elasticity such as rubber. The developing roller shaft <NUM> is a solid cylindrical member that penetrates the developing roller body <NUM> in the first direction. The developing roller shaft <NUM> is made of metal or electrically conductive resin.

The developing roller body <NUM> is fixed to the developing roller shaft <NUM> so that relative rotation of the developing roller body <NUM> with respect to the developing roller shaft <NUM> is prevented. That is, the developing roller body <NUM> is rotatable together with the developing roller shaft <NUM> about the developing roller-axis. An outer circumferential surface of the developing roller body <NUM> having one end portion in the second direction exposed to an outside of the casing <NUM> through the opening portion 10C. Another end portion in the second direction of the outer circumferential surface of the developing roller body <NUM> is positioned inside the casing <NUM>.

A developing roller gear (not illustrated) is coupled to one end portion in the first direction of the developing roller shaft <NUM>. The developing roller gear is positioned at the first outer surface <NUM>. The developing roller gear is fixed to the developing roller shaft <NUM> so that relative rotation between the developing roller gear and the developing roller shaft <NUM> is prevented. Hence, rotation of the developing roller gear causes rotation of the developing roller shaft <NUM> to rotate the developing roller body <NUM> together with the developing roller shaft <NUM>.

Incidentally, the developing roller shaft <NUM> may not penetrate the developing roller body <NUM> in the first direction. For example, two developing roller shafts <NUM> may extend in the first direction from both ends in the first direction of the developing roller body <NUM>, respectively.

As illustrated in <FIG> and <FIG>, the developing cartridge <NUM> includes a gear portion <NUM>. The gear portion <NUM> is positioned at the first outer surface <NUM> of the casing <NUM>. The gear portion <NUM> includes the developing roller gear described above, a coupling <NUM>, and a gear cover <NUM>.

The coupling <NUM> is a rotary member configured to receive a driving force supplied from a power source of the image forming apparatus <NUM>. The coupling <NUM> is rotatable about a rotational axis extending in the first direction. The coupling <NUM> has a fixing hole <NUM> recessed in the first direction. Upon attachment of the drum cartridge <NUM> to which the developing cartridges <NUM> are attached to the main body portion <NUM> of the image forming apparatus <NUM>, a transmission shaft (not illustrated) of the main body portion <NUM> is inserted into the fixing hole <NUM>. As a result, the transmission shaft and the coupling <NUM> are coupled to each other so as not to rotate relative to each other. Accordingly, rotation of the transmission shaft causes rotation of the coupling <NUM>, which causes rotation of the developing roller gear along with the rotation of the developing roller <NUM>. Further, rotation of the coupling <NUM> also causes rotations of a supply roller (not illustrated) and an agitator (not illustrated).

The casing <NUM> has an outer surface positioned at another end portion in the third direction of the casing <NUM>. A handle <NUM> is positioned at the outer surface to be gripped by a user.

When performing a printing process in the image forming apparatus <NUM>, the controller <NUM> drives a motor (not illustrated). As the motor is driven, the photosensitive drum <NUM> and the developing roller <NUM> receive a driving force from the motor through the transmission shaft and the coupling <NUM> to rotate. Further, the controller <NUM> supplies electric power to each charger (not illustrated) to charge the outer circumferential surface of the corresponding photosensitive drum <NUM>. Further, the controller <NUM> turns on each light source (not illustrated) so that the light source emits light onto the outer circumferential surface of the corresponding photosensitive drum <NUM>. Accordingly, an electrostatic latent image corresponding to an image to be printed is formed on the outer circumferential surface of the photosensitive drum <NUM>.

The toner accommodated in the developing cartridge <NUM> is supplied through the developing roller <NUM> to the electrostatic latent image formed on the photosensitive drum <NUM>. As a result, the electrostatic latent image becomes a visible toner image on the outer circumferential surface of the photosensitive drum <NUM>. In the meantime, a printing sheet is conveyed to a portion between the photosensitive drum <NUM> and the transfer belt. Hence, the toner image is transferred from the outer circumferential surface of the photosensitive drum <NUM> to the printing sheet. The printing sheet carrying the toner image thereon is then conveyed to a fixing unit (not illustrated) provided in the image forming apparatus <NUM> where the toner image is thermally fixed to the printing sheet. As a result, an image is printed on the printing sheet.

In the image forming apparatus <NUM>, it is preferable that each of the developing rollers <NUM> be separated from the corresponding one of the photosensitive drums <NUM> in order to change colors for printing or during a standby period. To this end, the image forming apparatus <NUM> according to the present embodiment provides a contacting state and separated state. In the contacting state of the image forming apparatus <NUM>, the developing rollers <NUM> and the corresponding photosensitive drums <NUM> are in contact with each other in a state where the developing cartridges <NUM> are attached to the drum cartridge <NUM>. In the separated state of the image forming apparatus <NUM>, the developing rollers <NUM> and the corresponding photosensitive drums <NUM> are separated from each other in the state where the developing cartridges <NUM> are attached the drum cartridge <NUM>.

To this effect, as components for realizing the contact and the separation between the developing rollers <NUM> and the corresponding photosensitive drums <NUM>, each of the developing cartridges <NUM> further includes a first cam <NUM>, a second cam <NUM>, a connection member <NUM>, two hooks <NUM>, a first guide groove <NUM>, a second guide groove <NUM>, two positioning grooves <NUM>, and an elastic member <NUM>. Also, as components for realizing the contact and the separation, the drum cartridge <NUM> further includes first cylinders <NUM> and second cylinders <NUM>. Still also, as components for realizing the contact and the separation, the main body portion <NUM> includes drive shafts <NUM>.

Hereinafter, components of the drum cartridge <NUM> for performing the contact and the separation between the developing rollers <NUM> and the corresponding photosensitive drums <NUM> will be described with reference to <FIG>. <FIG> is a perspective view of the first cylinder <NUM>. <FIG> is a perspective view of the second cylinder <NUM>.

As illustrated in <FIG>, in a state where the developing cartridges <NUM> are attached to the drum cartridge <NUM>, the first outer surfaces <NUM> of the developing cartridges <NUM> face an inner surface of the side frame <NUM> in the first direction. Similarly, in a state where the developing cartridges <NUM> are attached to the drum cartridge <NUM>, the second outer surfaces <NUM> of the developing cartridges <NUM> face an inner surface of the side frame <NUM> in the first direction.

As indicated by a broken line in a partial enlarged view in <FIG>, the side frame <NUM> includes the first cylinders <NUM>. That is, the first cylinders <NUM> are positioned at one end portion in the first direction of the frame <NUM>.

<FIG> is an exploded perspective view of the first cylinder <NUM> and a bearing <NUM> that holds the first cylinder <NUM>. As illustrated in <FIG>, the first cylinder <NUM> is cylindrical in shape centered on a first rotational axis extending in the third direction. The first cylinder <NUM> has an outer circumferential surface serving as a first contact surface <NUM> that is capable of contacting a first inclined surface 61c of the first cam <NUM> (described later). The first cylinder <NUM> has one end portion and another end portion in the third direction each rotatably supported by the bearing <NUM>. With this configuration, the first cylinder <NUM> is rotatable about the first rotational axis extending in the third direction.

As indicated by a broken line in another partial enlarged view in <FIG>, the side frame <NUM> includes the second cylinders <NUM>. That is, the second cylinders <NUM> are positioned at another end portion in the first direction of the frame <NUM>.

<FIG> is an exploded perspective view of the second cylinder <NUM> and a bearing <NUM> that holds the second cylinder <NUM>. As illustrated in <FIG>, the second cylinder <NUM> is cylindrical in shape centered on a second rotational axis extending in the third direction. The second cylinder <NUM> has an outer circumferential surface functioning as a second contact surface <NUM> capable of contacting a second inclined surface 62c of the second cam <NUM> (described later). The second cylinder <NUM> has one end portion and another end portion in the third direction each rotatably supported by the bearing <NUM>. Thus, the second cylinder <NUM> is rotatable about the second rotational axis extending in the third direction.

Each of the first cylinders <NUM> and corresponding each of the second cylinder <NUM> are aligned with each other in the first direction as a pair. As will be described later, components in the developing cartridge <NUM> for performing the contact and the separation between the developing rollers <NUM> and the corresponding photosensitive drums <NUM> are capable of contacting the first contact surface <NUM> of the first cylinder <NUM> and the second contact surface <NUM> of the second cylinder <NUM>.

Hereinafter, components of the main body portion <NUM> for performing the contact and the separation between the developing rollers <NUM> and the corresponding photosensitive drums <NUM> will be described. The main body portion <NUM> includes the drive shafts <NUM> as illustrated in <FIG>, <FIG>, <FIG> and <FIG>. Each of the drive shafts <NUM> has one of a solid cylindrical shape and solid prismatic columnar shape extending in the first direction. Each of the drive shafts <NUM> is movable in the first direction between an advanced position and a retracted position upon receiving a driving force from a power source of the main body portion <NUM>.

Next, components of the developing cartridges <NUM> for realizing the contact and the separation between the developing rollers <NUM> and the corresponding photosensitive drums <NUM> will be described with reference to <FIG>. <FIG> is a perspective view of the first cam <NUM>, the second cam <NUM>, and the connection member <NUM>. <FIG> is a perspective view of the developing cartridge <NUM> in which the connection member <NUM> has been removed. <FIG> is a view particularly illustrating a portion in the vicinity of a retainer 61e of the first cam <NUM>.

As illustrated in <FIG>, the first cam <NUM> is positioned at the one end portion <NUM> of the casing <NUM> and positioned at the third outer surface <NUM> of the casing <NUM>. The first cam <NUM> includes a first end 61a, and a second end 61b positioned closer to the other end portion <NUM> of the casing <NUM> in the first direction than the first end 61a is to the other end portion <NUM>.

The first cam <NUM> further has the first inclined surface 61c inclined so as to be distant from the casing <NUM> as extending from the second end 61b toward the first end 61a. In other words, the first inclined surface 61c approaches the casing <NUM> in the second direction as extending in the first direction from one side toward another side of the casing <NUM>. In the state where each developing cartridge <NUM> is attached to the drum cartridge <NUM>, the first cam <NUM> is movable relative to the photosensitive drum <NUM> in the second direction together with the casing <NUM> and the developing roller <NUM>. Further, as will be described later in detail, the first cam <NUM> is movable in the first direction relative to the casing <NUM> and the developing roller <NUM> between a first position and a second position. The first cam <NUM> in the second position is positioned closer to the other end portion <NUM> than the first cam <NUM> in the first position is to the other end portion <NUM>.

The first guide groove <NUM> is positioned at the third outer surface <NUM> of the casing <NUM>. Specifically, the lid 10B has the first guide groove <NUM> at one end portion in the first direction thereof. The first guide groove <NUM> extends in the first direction and is recessed from an outer surface of the lid 10B toward another end portion in the second direction of the lid 10B. With this configuration, the first guide groove <NUM> can guide movement of the first cam <NUM> between the first position and the second position.

As illustrated in <FIG> and <FIG>, the first end 61a has a pressure contact surface 61d. The pressure contact surface 61d is a surface that extends perpendicularly to the first direction.

As illustrated in <FIG> and <FIG>, the second cam <NUM> is positioned at the other end portion <NUM> of the casing <NUM> and positioned at the third outer surface <NUM> of the casing <NUM>. The second cam <NUM> includes a third end 62a, and a fourth end 62b positioned closer to the other end portion <NUM> of the casing <NUM> in the first direction than the third end 62a is to the other end portion <NUM>.

The second cam <NUM> has the second inclined surface 62c inclined so as to be distant from the casing <NUM> as extending from the fourth end 62b toward the third end 62a. In other words, the second inclined surface 62c approaches the casing <NUM> in the second direction as extending in the first direction from the one side toward the other side of the casing <NUM>. In the state where the developing cartridge <NUM> is attached to the drum cartridge <NUM>, the second cam <NUM> is movable relative to the photosensitive drum <NUM> in the second direction together the casing <NUM> and the developing roller <NUM>. In addition, the second cam <NUM> is movable in the first direction relative to the casing <NUM> and the developing roller <NUM> between a third position and a fourth position. The second cam <NUM> in the fourth position is positioned closer to the other end portion <NUM> than the second cam <NUM> in the third position is to the other end portion <NUM>.

The second guide groove <NUM> is positioned at the third outer surface <NUM> of the casing <NUM>. Specifically, the lid 10B has the second guide groove <NUM> at another end portion in the first direction thereof. The second guide groove <NUM> extends in the first direction and is recessed from the outer surface of the lid 10B toward the other end portion in the second direction of the lid 10B. Hence, the second guide groove <NUM> can guide movement of the second cam <NUM> between the third position and the fourth position.

In the present embodiment, the connection member <NUM> is a sheet-like member formed of material having flexibility such as polyethylene terephthalate resin. In the following description, a region between one end and another end of the connection member <NUM> will occasionally be referred to as "intermediate portion of the connection member <NUM>".

The connection member <NUM> connects the first cam <NUM> and the second cam <NUM> to each other. Specifically, the connection member <NUM> connects the first end 61a of the first cam <NUM> and the fourth end 62b of the second cam <NUM> to each other through the hooks <NUM>. More specifically, one end of the connection member <NUM> is connected to the first end 61a of the first cam <NUM> through one of the hooks <NUM>, and another end of the connection member <NUM> is connected to the fourth end 62b of the second cam <NUM> through the remaining one of the hooks <NUM>.

The connection member <NUM> has a portion extending in the first direction and is positioned at the fourth outer surface <NUM> of the casing <NUM>. In other words, the portion of the connection member <NUM> extends in the first direction along the fourth outer surface <NUM>. With this arrangement, a sufficient distance from the one end to the other end of the connection member <NUM> can be obtained. Further, the connection member <NUM> can have at least two bending portions. In other words, the intermediate portion of the connection member <NUM> has a portion extending in the first direction, and another portion extending in a direction crossing the first direction.

As illustrated in <FIG> and <FIG>, the two positioning grooves <NUM> are positioned at the fourth outer surface <NUM> of the casing <NUM> with an interval therebetween in the first direction. In the present embodiment, each of the positioning grooves <NUM> includes a pair of groove walls <NUM> extending in the first direction and protruding from the fourth outer surface <NUM> in the second direction. At least a portion of the connection member <NUM> is positioned within the positioning grooves <NUM> (i.e., between the pair of groove walls <NUM> of each positioning groove <NUM>). This configuration can prevent the intermediate position of the connection member <NUM> from deviating in position in the third direction on the fourth outer surface <NUM>. The two positioning grooves <NUM> are an example of a groove.

As illustrated in <FIG>, <FIG> and <FIG>, the elastic member <NUM> is a tension coil spring in the present embodiment. The elastic member <NUM> is positioned at the other end portion <NUM> of the casing <NUM> and positioned at the third outer surface <NUM>. The elastic member <NUM> has one end connected to the second cam <NUM>, and another end connected to the third outer surface <NUM> of the casing <NUM>. The elastic member <NUM> urges the second cam <NUM> in a direction from the fourth position toward the third position.

As illustrated in <FIG>, the first cam <NUM> includes the retainer 61e for preventing the first cam <NUM> from disengaging from the first guide groove <NUM>. The retainer 61e protrudes from a body of the first cam <NUM> in the third direction from one side toward another side. The gear cover <NUM> has a notch 43a on a wall surface (side surface) at one end portion thereof in the second direction. The notch 43a is open toward the other side in the first direction of the casing <NUM>. As illustrated in <FIG>, the retainer 61e of the first cam <NUM> is capable of contacting an inner edge of the notch 43a. By this contact, further movement of the first cam <NUM> in the first direction from the other side toward the one side can be restrained. In other words, disengagement of the first cam <NUM> from the first guide groove <NUM> can be avoided by the contact between the retainer 61e and the inner edge of the notch 43a.

Hereinafter, how each component operates for realizing switching between the contact and the separation will be described with reference to <FIG>.

<FIG> is a view of the developing cartridge <NUM> and the photosensitive drum <NUM> in the contacting state of the image forming apparatus <NUM> as viewed in the first direction from the other side toward the one side. <FIG> is a view of the developing cartridge <NUM> in the contacting state of the image forming apparatus <NUM> as viewed in the third direction from the other side toward the one side. <FIG> is a perspective view of the developing cartridge <NUM> and the photosensitive drum <NUM> in the contacting state of the image forming apparatus <NUM>. <FIG> is a view of the developing cartridge <NUM> and the photosensitive drum <NUM> in the separated state of the image forming apparatus <NUM> as viewed in the first direction from the other side toward the one side. <FIG> is a view of the developing cartridge <NUM> in the separated state of the image forming apparatus <NUM> as viewed in the third direction from the other side toward the one side. <FIG> is a perspective view of the developing cartridge <NUM> and the photosensitive drum <NUM> in the separated state of the image forming apparatus <NUM>.

In the image forming apparatus <NUM>, when the drive shaft <NUM> is driven to move toward the advanced position from the one side toward the other side in the first direction of the casing <NUM>, the pressure contact surface 61d of the first cam <NUM> is pressed by the drive shaft <NUM>. In accordance with application of the pressing force by the drive shaft <NUM>, the first cam <NUM> moves from the first position to the second position within the first guide groove <NUM>. As the first cam <NUM> moves to its second position, a tensile force of the connection member <NUM> becomes greater than a tensile force of the connection member <NUM> in the first position of the first cam <NUM>. When the tensile force of the connection member <NUM> becomes greater than the urging force of the elastic member <NUM>, the fourth end 62b of the second cam <NUM> is pulled by the connection member <NUM>, whereby the second cam <NUM> moves from the third position to the fourth position within the second guide groove <NUM>.

The first inclined surface 61c is in contact with the first contact surface <NUM> of the first cylinder <NUM>. Here, a contacting position of the first inclined surface 61c with respect to the first contact surface <NUM> is gradually shifted from a position close to the second end 61b (see <FIG>) to a position close to the first end 61a (see <FIG>). As a result, a distance in the second direction between the casing <NUM> and the first contact surface <NUM> of the first cylinder <NUM> gradually increases. A pressing force applied to the first inclined surface 61c by the first contact surface <NUM> of the first cylinder <NUM> causes the casing <NUM> and the developing roller <NUM> to move away from the photosensitive drum <NUM>.

Similarly, the second inclined surface 62c is in contact with the second contact surface <NUM> of the second cylinder <NUM>. Here, a contacting position of the second inclined surface 62c with respect to the second contact surface <NUM> is gradually shifted from a position close to the fourth end 62b (see <FIG>) to a position close to the third end 62a (see <FIG>). As a result, a distance in the second direction between the casing <NUM> and the second contact surface <NUM> of the second cylinder <NUM> gradually increases. In this way, the casing <NUM> and the developing roller <NUM> move away from the photosensitive drum <NUM> since the second inclined surface 62c is applied with a pressing force by the second contact surface <NUM> of the second cylinder <NUM>.

As described above, both end portions in the first direction of the casing <NUM> (i.e., the first inclined surface 61c and the second inclined surface 62c) are respectively pressed by the first contact surface <NUM> of the first cylinder <NUM> and the second contact surface <NUM> of the second cylinder <NUM> those are spaced away from each other in the first direction. This configuration can accurately move the casing <NUM> and the developing roller <NUM> away from the photosensitive drum <NUM> while avoiding inclination of the casing <NUM> relative to the first direction.

On the other hand, when the drive shaft <NUM> is driven to move toward its retracted position from the other side to the one side in the first direction of the casing <NUM>, the second cam <NUM> moves back from the fourth position to the third position within the second guide groove <NUM> because the urging force of the elastic member <NUM> becomes greater than the tensile force of the connection member <NUM>. Further, the first cam <NUM> also moves back from the second position to the first position within the first guide groove <NUM> because the first end 61a of the first cam <NUM> is pulled by the connection member <NUM>. At this time, disengagement of the first cam <NUM> from the first guide groove <NUM> can be prevented due to the contact of the retainer 61e of the first cam <NUM> with the inner edge of the notch <NUM> a.

In the meantime, the frame <NUM> of the drum cartridge <NUM> further includes an urging mechanism (not illustrated) for urging the casing <NUM> toward the photosensitive drum <NUM>. The urging mechanism urges the developing cartridge <NUM> in the second direction from the other side toward the one side, whereby the developing roller <NUM> and the photosensitive drum <NUM> are again brought into contact with each other. As such, switching between the contacting state (see <FIG>) and the separated state (see <FIG>) can be realized in the image forming apparatus <NUM>.

As described above, the developing cartridge <NUM> according to the present embodiment includes the casing <NUM>, the developing roller <NUM>, the first cam <NUM>, the second cam <NUM>, and the connection member <NUM>. The second cam <NUM> moves from the third position to the fourth position in accordance with the movement of the first cam <NUM> from the first position to the second position due to the tensile force of the connection member <NUM>. During the movement, the first cam <NUM> and the second cam <NUM> are respectively pressed by the arcuate surfaces (the first and second contact surfaces <NUM> and <NUM>) of the drum cartridge <NUM>, thereby separating the developing roller <NUM> from the photosensitive drum <NUM>.

As such, in the developing cartridge <NUM> according to the present embodiment, the separation of the developing roller <NUM> from the photosensitive drum <NUM> can be performed by the driving force applied only to the one side in the first direction of the developing cartridge <NUM>. Application of a driving force to both sides in the first direction of the developing cartridge <NUM> is unnecessary.

Further, in the developing cartridge <NUM> according to the present embodiment, the first cam <NUM> and the second cam <NUM> are positioned at the third outer surface <NUM> of the casing <NUM>. In addition, at least a portion of the connection member <NUM> extends in the first direction along the fourth outer surface <NUM> of the casing <NUM>. With this configuration, a sufficient length from the one end to the other end of the connection member <NUM> can be obtained, and at least two bending portions can be provided in the connection member <NUM>. As a result, a tensile force can be generated in the connection member <NUM> with high accuracy.

Further, in the developing cartridge <NUM> according to the present embodiment, the first cam <NUM> has the first inclined surface 61c, and the second cam <NUM> has the second inclined surface 62c. With this configuration, the first cam <NUM> and the second cam <NUM> can be accurately pressed by the first contact surface <NUM> and the second contact surface <NUM> of the drum cartridge <NUM>, respectively, while suppressing inclination of the developing cartridge <NUM>.

Further, the developing cartridge <NUM> according to the present embodiment includes the elastic member <NUM>. Hence, when a tensile force of the connection member <NUM> decreases after the second cam <NUM> is pulled from the third position to the fourth position due to the tensile force of the connection member <NUM>, the second cam <NUM> can move back from the fourth position to the third position owing to the urging force of the elastic member <NUM>. As a result, the developing roller <NUM> once moved away from the photosensitive drum <NUM> can be easily returned to its original position (i.e., the position where the developing roller <NUM> is in contact with the photosensitive drum <NUM>).

Further, in the developing cartridge <NUM> according to the present embodiment, the casing <NUM> has the two positioning grooves <NUM>. At least a portion of the intermediate position of the connection member <NUM> is positioned within each of the positioning grooves <NUM>. With this configuration, the positioning grooves <NUM> can restrain at least the portion of the intermediate portion of the connection member <NUM> from displacing in the third direction.

Further, the casing <NUM> of the developing cartridge <NUM> according to the present embodiment includes the lid 10B. The lid 10B has the first guide groove <NUM> and the second guide groove <NUM>. Since the lid 10B is a flat plate like member, the first guide groove <NUM> and the second guide groove <NUM> can be easily formed in the lid 10B.

Further, in the developing cartridge <NUM> according to the present embodiment, the first cam <NUM> includes the retainer 61e. This retainer 61e can restrain disengagement of the first cam <NUM> from the first guide groove <NUM> due to the application of tensile force by the connection member <NUM>.

Further, in the developing cartridge <NUM> according to the present embodiment, the first end 61a of the first cam <NUM> has the pressure contact surface 61d. The first cam <NUM> moves from the first position to the second position when the pressure contact surface 61d receives a pressing force. That is, owing to the pressure contact surface 61d, the first cam <NUM> can move from the first position to the second position. Simultaneously, the second cam <NUM> can move from the third position to the fourth position by the tensile force of the connection member <NUM> in accordance with movement of the first cam <NUM> from the first position to the second position.

Further, the main body portion <NUM> includes the drive shaft <NUM> in the present embodiment. In the case where the drive shaft <NUM> applies a pressing force to the pressure contact surface 61d of the first cam <NUM>, the first cam <NUM> moves from the first position to the second position, and the second cam <NUM> moves from the third position to the fourth position due to the tensile force of the connection member <NUM>. Hence, the developing roller <NUM> can separate from the photosensitive drum <NUM> by the driving force received from the main body portion <NUM>.

Further, in the present embodiment, the drum cartridge <NUM> has the first contact surface <NUM> and the second contact surface <NUM>. In the state where the developing cartridge <NUM> is attached to the drum cartridge, the first contact surface <NUM> is in contact with the first inclined surface 61c, and the second contact surface <NUM> is in contact with the second inclined surface 62c. Accordingly, the first cam <NUM> moves in the first direction from the one side toward the other side while in contact with the first contact surface <NUM>, and the second cam <NUM> also moves in the first direction from the one side toward the other side while in contact with the second contact surface <NUM>.

With this configuration, the first inclined surface 61c is pressed by the first contact surface <NUM> and the second inclined surface 62c is pressed by the second contact surface <NUM>, thereby causing the casing <NUM> and the developing roller <NUM> to move from a contacting state where the developing roller <NUM> is in contact with the photosensitive drum <NUM> to a separated state where the developing roller <NUM> is separated from the photosensitive drum <NUM>. Also, this configuration can restrain the casing <NUM> and the developing roller <NUM> from being inclined relative to the first direction.

Further, the first cylinder <NUM> is rotatable about the first rotational axis, and the second cylinder <NUM> is rotatable about the second rotational axis in the present embodiment. Accordingly, a frictional force generated between the first inclined surface 61c and the first contact surface <NUM>, and a frictional force generated between the second inclined surface 62c and the second contact surface <NUM> can be reduced in the case where the first cam <NUM> and the second cam <NUM> move in the first direction toward from the one side toward the other side in a state where the first contact surface <NUM> is in contact with the first inclined surface 61c and the second contact surface <NUM> is in contact with the second inclined surface 62c.

While the description has been made in detail with reference to the specific embodiment, it would be apparent to those skilled in the art that various modifications can be made thereto.

In the above-described embodiment, at least a portion of the connection member <NUM> extends in the first direction on the fourth outer surface <NUM> of the casing <NUM>. Instead of the above configuration, at least a portion of the connection member <NUM> may extend in the first direction on the outer surface of the casing <NUM> where the handle <NUM> is positioned. That is, it is preferable that the connection member <NUM> has a portion that extends in the first direction on an outer surface of the casing <NUM> different from the third outer surface <NUM>.

While only the first cam <NUM> has the retainer 61e in the above-described embodiment, not only the first cam <NUM> but also the second cam <NUM> may have a retainer.

In the above-described embodiment, the connection member <NUM> is a sheet-like member. However, the connection member <NUM> may be a wire member. Further, the connection member <NUM> is formed of resin in the above-described embodiment. However, instead of resin, the connection member <NUM> may be formed of metal (such as leaf spring).

In the above-described embodiment, two of the positioning grooves <NUM> are spaced away from each other in the first direction on the fourth outer surface <NUM> of the casing <NUM>. However, one positioning groove <NUM> may be positioned to extend over an entire region of the casing <NUM> from the one end portion <NUM> to the other end portion <NUM> in the first direction.

Claim 1:
A developing cartridge comprising:
a casing (<NUM>) configured to accommodate developing agent therein, the casing (<NUM>) including one end portion (<NUM>) and another end portion (<NUM>) spaced apart from the one end portion (<NUM>) in a first direction;
a developing roller (<NUM>) rotatable about a developing roller axis extending in the first direction; and
a first cam (<NUM>) positioned at the one end portion (<NUM>) of the casing (<NUM>), the first cam (<NUM>) being movable relative to the casing (<NUM>) and the developing roller (<NUM>) in the first direction between a first position and a second position, the first cam (<NUM>) in the second position being positioned closer to the another end portion (<NUM>) of the casing (<NUM>) in the first direction than the first cam (<NUM>) in the first position is to the another end portion (<NUM>) of the casing (<NUM>);
a second cam (<NUM>) positioned at the another end portion (<NUM>) of the casing (<NUM>), the second cam (<NUM>) being movable relative to the casing (<NUM>) and the developing roller (<NUM>) in the first direction between a third position and a fourth position, the second cam (<NUM>) in the fourth position being positioned closer to the another end portion (<NUM>) of the casing (<NUM>) in the first direction than the second cam (<NUM>) in the third position is to the another end portion (<NUM>) of the casing (<NUM>); and
a connection member (<NUM>) connecting the first cam (<NUM>) and the second cam (<NUM>) to each other,
characterized in that
the second cam (<NUM>) is movable from the third position to the fourth position due to a tensile force of the connection member (<NUM>) in accordance with movement of the first cam (<NUM>) from the first position to the second position.