Image forming apparatus including cartridge support member and cartridge including movable detection member

This application claims priority from Japanese Patent Application No. 2016-185336 filed Sep. 23, 2016. The entire content of the priority application is incorporated herein by reference.

The present disclosure relates to an image forming apparatus and a drum unit.

There has been known an image forming apparatuses of a type that is provided with a plurality of cartridges accommodating toner therein. The cartridges can be attached to, and detached from, the image forming apparatus.

Prior art discloses an image forming apparatus that includes a drum unit and a plurality of developer cartridges. The drum unit can hold a plurality of developer cartridges. The drum unit is movable between an inside position, at which the drum unit is disposed inside of the casing of the image forming apparatus, and an outside position, at which the drum unit is disposed outside of the casing of the image forming apparatus.

Each developer cartridge includes a detecting gear. The detecting gear includes a protrusion. The drum unit includes a lever. The main body casing includes a photo-sensor. After the developer cartridge is attached to the drum unit, when the detection gear rotates, the protrusion abuts on the lever, whereupon the lever pivotally moves. The photo-sensor detects the pivotal movement of the lever, and generates a signal. Based on the signal outputted from the photo-sensor, the image forming apparatus acquires the information on the developer cartridge.

There is a demand for downsizing the above-described conventional image forming apparatus.

An object of the disclosure is therefore to provide an image forming apparatus and a drum unit which can be made smaller in size.

According to one aspect, an image forming apparatus is provided. The image forming apparatus includes: a housing; a drive source; a cartridge; a main-body-side electrical contact; a cartridge support member; a lever; and a detector. The cartridge is configured to accommodate toner therein. The cartridge includes a detection member movable upon receipt of driving force from the drive source. The main-body-side electrical contact is provided at the housing. The cartridge is detachably attachable to the cartridge support member. The cartridge support member is movable between an inside position at which the cartridge support member is positioned inside the housing, and an outside position at which the cartridge support member is positioned outside of the housing. The lever is provided at the cartridge support member. The lever includes a support-member-side electrical contact. The lever is movable between a first position and a second position by driving force transmitted from the detection member in a state where the cartridge is attached to the cartridge support member and the cartridge support member is positioned at the inside position. In the first position, the main-body-side electrical contact is out of electrical contact with the support-member-side electrical contact. In the second position, the main-body-side electrical contact is in electrical contact with the support-member-side electrical contact. The detector is configured to detect electrical connection between the main-body-side electrical contact and the support-member-side electrical contact when the lever is in the second position.

According to another aspect, a drum unit, to which a cartridge is detachably attachable, is provided. The cartridge is configured to accommodate toner therein and includes a detection member movable upon receipt of driving force. The drum unit includes: a photosensitive drum; and a lever including an electrical contact. The lever is movable upon receipt of driving force from the detection member in a state where the cartridge is attached to the drum unit.

The particular features and advantages of the disclosure will become apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 schematically illustrates a structure of an image forming apparatus according to an embodiment;

FIG. 2 is a perspective view showing an entire part of a cartridge support member in a state where the cartridge support member is removed from a housing of the image forming apparatus and is disposed outside the housing;

FIG. 3 is a perspective view of a first wall constituting the cartridge support member of FIG. 2 , viewed from an outward side of the cartridge support member, FIG. 3 illustrating a state of the first wall from which covers have been removed;

FIG. 4 is a perspective view of the first wall viewed from an inward side of the cartridge support member;

FIG. 5 is an enlarged view of an essential part of the perspective view in FIG. 3 , illustrating how a support-member-side developing-bias electrode, a tension spring, a lever, and a connecting member for a magenta-toner cartridge are arranged on a second surface of the first wall;

FIG. 6 is an enlarged view of an essential part of the perspective view in FIG. 4 , illustrating how a protrusion provided at a distal end of the lever is inserted into an opening of the first wall and protrudes from a second surface side of the first wall to a first surface side of the first wall;

FIG. 7 illustrates how the support-member-side developing-bias electrode, the tension spring, the lever, and the connecting member for the magenta-toner cartridge are located in a state where the magenta-toner cartridge is not supported in the cartridge support member;

FIG. 8 is a partially exploded perspective view of the magenta-toner cartridge; and

FIGS. 9-14 illustrate how various components provided to the magenta-toner cartridge and various components provided to the cartridge support member for the magenta-toner cartridge are moved, wherein:

FIG. 9 illustrates how a shaft and a detecting protrusion of the magenta-toner cartridge and the lever of the cartridge support member for the magenta-toner cartridge are located in a state where the magenta-toner cartridge is at an unlocked position and the lever is at a fourth position;

FIG. 10 illustrates how the support-member-side developing-bias electrode, tension spring, lever, and connecting member of the cartridge support member for the magenta-toner cartridge are located in the state shown in FIG. 9 ;

FIG. 11 illustrates how the shaft and the detecting protrusion of the magenta-toner cartridge and the lever of the cartridge support member for the magenta-toner cartridge are located in a state where the magenta-toner cartridge is at a locked position and the lever is at a first position;

FIG. 12 illustrates how the support-member-side developing-bias electrode, tension spring, lever, and connecting member of the cartridge support member for the magenta-toner cartridge are located in the state shown in FIG. 11 ;

FIG. 13 illustrates how the shaft and the detecting protrusion of the magenta-toner cartridge and the lever of the cartridge support member for the magenta-toner cartridge are located in a state where the magenta-toner cartridge is at the locked position and the lever is at a second position; and

FIG. 14 illustrates how the support-member-side developing-bias electrode, tension spring, lever, and connecting member of the cartridge support member for the magenta-toner cartridge are located in the state shown in FIG. 13 .

An image forming apparatus according to an embodiment will be described while referring to the accompanying drawings wherein like parts and components are designated by the same reference numerals to avoid duplicating description.

1. Outline of the Image Forming Apparatus

An image forming apparatus 1 will be schematically described with reference to FIGS. 1, 2, 7, and 8 .

As shown in FIG. 1 , the image forming apparatus 1 includes: a housing 2 ; a cartridge support member 3 ; and a plurality of cartridges 4 K, 4 Y, 4 M and 4 C. The cartridge 4 K stores black toner. The cartridge 4 Y stores yellow toner. The cartridge 4 M stores magenta toner. The cartridge 4 M will be referred to also as “magenta-toner cartridge 4 M” hereinafter. The cartridge 4 C stores cyan toner. As shown in FIGS. 2 and 7 , the image forming apparatus 1 includes: main-body-side developing-bias contacts 201 K, 201 Y, 201 M and 201 C ( FIG. 2 ); main-body-side detection contacts 202 K, 202 Y, 202 M and 202 C ( FIG. 2 ); and a detector 203 ( FIG. 7 ). The image forming apparatus 1 further includes: a drive power source 211 (e.g., motor) and main-body-side couplings 210 K, 210 Y, 210 M and 210 C, among which only the drive power source 211 and the main-body-side coupling 210 M are shown in FIG. 8 .

1.1 Housing

As shown in FIG. 1 , the housing 2 constitutes an outer shell of the image forming apparatus 1 . The housing 2 accommodates therein the cartridge support member 3 and the cartridges 4 K, 4 Y, 4 M and 4 C.

1.2 Main-Body-Side Developing-Bias Contacts and Main-Body-Side Detection Contacts

As shown in FIG. 2 , the main-body-side developing-bias contacts 201 K, 201 Y, 201 M and 201 C are provided in the housing 2 . The main-body-side developing-bias contacts 201 K, 201 Y, 201 M and 201 C are configured to apply developing biases to support-member-side developing-bias electrodes 13 K, 13 Y, 13 M and 13 C (described later), respectively. That is, the main-body-side developing-bias contacts 201 K, 201 Y, 201 M and 201 C are configured so as to be electrically connected to the support-member-side developing-bias electrodes 13 K, 13 Y, 13 M and 13 C, respectively.

The main-body-side detection contacts 202 K, 202 Y, 202 M and 202 C are provided in the housing 2 . All of the main-body-side detection contacts 202 K, 202 Y, 202 M and 202 C are in electrical connection with the single detector 203 (see FIG. 7 ).

1.3 Detector

As shown in FIG. 7 , the detector 203 is provided in the housing 2 . The detector 203 is an electrical circuit configured to detect: whether the main-body-side detection contact 202 K is brought into electrical connection with a support-member-side detection contact 42 K constituting a lever 12 K (described later); whether the main-body-side detection contact 202 Y is brought into electrical connection with a support-member-side detection contact 42 Y constituting a lever 12 Y (to be described later); whether the main-body-side detection contact 202 M is brought into electrical connection with a support-member-side detection contact 42 M constituting a lever 12 M (described later); and whether the main-body-side detection contact 202 C is brought into electrical connection with a support-member-side detection contact 42 C constituting a lever 12 C (described later).

1.4 Drive Mechanism

As shown in FIG. 8 , the main-body-side couplings 210 K, 210 Y, 210 M and 210 C are provided in the housing 2 . The main-body-side coupling 210 K is configured so as to be connected to a coupling 107 K provided to the cartridge 4 K. The main-body-side coupling 210 Y is configured so as to be connected to a coupling 107 Y provided to the cartridge 4 Y. The main-body-side coupling 210 M is configured so as to be connected to a coupling 107 M provided to the cartridge 4 M. The main-body-side coupling 210 C is configured so as to be connected to a coupling 107 C provided to the cartridge 4 C.

The drive power source 211 is provided in the housing 2 . The drive power source 211 is configured to supply drive force to the main-body-side couplings 210 K, 210 Y, 210 M and 210 C.

1.5 Cartridge Support Member

As shown in FIG. 1 , the cartridge support member 3 is configured to support the cartridges 4 K, 4 Y, 4 M and 4 C. The cartridges 4 K, 4 Y, 4 M and 4 C can be attached to and detached from the cartridge support member 3 . The cartridge support member 3 is movable between an inside position, at which the cartridge support member 3 is disposed inside the housing 2 , and an outside position, at which the cartridge support member 3 is disposed outside the housing 2 . The cartridge support member 3 can be inserted into and removed from the housing 2 . Instead, the cartridge support member 3 may not be removed from the housing 2 . In the present example, the cartridge support member 3 is a drum unit including a plurality of photosensitive drums 5 K, 5 Y, 5 M and 5 C.

In the cartridge support member 3 , the photosensitive drums 5 K, 5 Y, 5 M and 5 C are arranged in a prescribed direction with intervals therebetween. The direction in which the photosensitive drums 5 K, 5 Y, 5 M and 5 C are arranged will be referred to as an “arrangement direction” hereinafter. The cartridge support member 3 is movable in the arrangement direction between the inside position and the outside position. Each of the photosensitive drums 5 K, 5 Y, 5 M and 5 C extends along its axis that extends in an axial direction, and is rotatable around the axis. The axial direction of each of the photosensitive drums 5 K, 5 Y, 5 M and 5 C will be referred to also as “a drum-axial direction” hereinafter. The drum-axial direction intersects with the arrangement direction. Preferably, the drum-axial direction is perpendicular to the arrangement direction. Electrostatic latent images are formed on the surfaces of the photosensitive drums 5 K, 5 Y, 5 M and 5 C, respectively.

1.6 Cartridges

The cartridges 4 K, 4 Y, 4 M and 4 C can be attached to, and detached from, the cartridge support member 3 . When the cartridges 4 K, 4 Y, 4 M and 4 C are attached to the cartridge support member 3 , the cartridges 4 K, 4 Y, 4 M and 4 C are arranged in the arrangement direction with the intervals therebetween. The cartridge 4 K is configured to supply toner to the photosensitive drum 5 K, thereby developing an electrostatic latent image formed on the surface of the photosensitive drum 5 K. The cartridge 4 Y is configured to supply toner to the photosensitive drum 5 Y, thereby developing an electrostatic latent image formed on the surface of the photosensitive drum 5 Y. The cartridge 4 M is configured to supply toner to the photosensitive drum 5 M, thereby developing an electrostatic latent image formed on the surface of the photosensitive drum 5 M. The cartridge 4 C is configured to supply toner to the photosensitive drum 5 C, thereby developing an electrostatic latent image formed on the surface of the photosensitive drum 5 C.

As shown in FIG. 1 , the cartridge 4 K is a developer cartridge including a developing roller 6 K. The developing roller 6 K of the cartridge 4 K contacts the photosensitive drum 5 K when the cartridge 4 K is attached in the cartridge support member 3 . The cartridge 4 Y is a developer cartridge including a developing roller 6 Y. The developing roller 6 Y of the cartridge 4 Y contacts the photosensitive drum 5 Y when the cartridge 4 Y is attached in the cartridge support member 3 . The cartridge 4 M is a developer cartridge including a developing roller 6 M. The developing roller 6 M of the cartridge 4 M contacts the photosensitive drum 5 M when the cartridge 4 M is attached in the cartridge support member 3 . The cartridge 4 C is a developer cartridge including a developing roller 6 C. The developing roller 6 C of the cartridge 4 C contacts the photosensitive drum 5 C when the cartridge 4 C is in the cartridge support member 3 .

1.7 Belt Unit and Fixing Device

The image forming apparatus 1 further includes a belt unit 7 and a fixing device 8 . The belt unit 7 is configured to transfer toner images from the surfaces of the photosensitive drums 5 K, 5 Y, 5 M and 5 C onto a sheet P. The belt unit 7 includes a conveying belt 7 A. The conveying belt 7 A is configured to convey the sheet P in the arrangement direction. The sheet P contacts the respective ones of the photosensitive drums 5 K, 5 Y, 5 M, and 5 C, while being conveyed by the conveying belt 7 A. Toner images formed on the surfaces of the photosensitive drums 5 K, 5 Y, 5 M and 5 C are transferred from the photosensitive drums 5 K, 5 Y, 5 M and 5 C onto the sheet P. The fixing device 8 is configured to apply heat and pressure to the sheet P, onto which the toner images have been transferred, thereby fixing the toner images on the sheet P.

2. Structure of the Cartridges

The cartridges 4 K, 4 Y, 4 M and 4 C have the same structure with one another. Hence, the cartridge 4 M will be described below with reference to FIG. 8 as a representative example of the cartridges 4 K, 4 Y, 4 M and 4 C.

The cartridge 4 M includes: a cartridge housing 101 M; a developing electrode 103 M; a detection member 104 M; and a cover 105 M.

2.1 Cartridge Housing

The cartridge housing 101 M extends in an axial direction of the developing roller 6 M. The axial direction of the developing roller 6 M will be referred to also as a “developing-roller axial direction” hereinafter. The cartridge housing 101 M has one end wall 1010 M and another end wall 1011 M spaced apart from each other in the developing-roller axial direction. The cartridge housing 101 M is configured to accommodate toner therein.

A boss 108 M is provided on an outer surface of the end wall 1010 M. The boss 108 M protrudes from the outer surface of the end wall 1010 M. The boss 108 M has a cylindrical shape extending in the developing-roller axial direction.

The coupling 107 M is provided on the other end wall 1011 M of the cartridge housing 101 M. The coupling 107 M is coupled to the main-body-side coupling 210 M while the cartridge support member 3 , supporting the cartridge 4 M, stays at the inside position. When the coupling 107 M is coupled to the main-body-side coupling 210 M, the coupling 107 M becomes capable of rotating together with the main-body-side coupling 210 M. That is, the coupling 107 M becomes capable of receiving a drive force from the drive power source 211 via the main-body-side coupling 210 M.

An agitator is provided inside the cartridge housing 101 M. The agitator includes an agitator shaft 106 M extending in the developing-roller axial direction. The drive force that the coupling 107 M received is transmitted from the coupling 107 M to the agitator shaft 106 M via a gear mechanism (not shown) provided on the outer surface of the other end wall 1011 M. The agitator is rotatable together with the agitator shaft 106 M around an axis of the agitator shaft 106 M. The agitator is configured to agitate toner in the cartridge housing 101 M and supply the toner to the developing roller 6 M. One end of the agitator shaft 106 M penetrates the end wall 1010 M of the cartridge housing 101 M and protrude outside of the cartridge housing 101 M. An agitator gear 102 M is attached to the one end of the agitator shaft 106 M that is disposed at the outward side of the end wall 1010 M in the developing-roller axial direction. The agitator gear 102 M is rotatable together with the agitator shaft 106 M.

2.2 Developing Electrode

The developing electrode 103 M is fixedly secured to the outer surface of the end wall 1010 M. The developing electrode 103 M includes: a bearing 110 M; and a shaft 109 M extending from the bearing 110 M outwardly in the developing-roller axial direction. In other words, the cartridge 4 M includes the shaft 109 M. The developing electrode 103 M is formed of electrically conductive material such as electrically conductive resin.

The shaft 109 M has a cylindrical shape extending in the developing-roller axial direction. As will be described later, the shaft 109 M includes a cartridge-side developing-bias contact 45 M on its circumferential surface ( FIG. 12 ). It can also be said that the cartridge 4 M has the cartridge-side developing-bias contact 45 M.

The bearing 110 M is a component for supporting the developing roller 6 M. That is, a developing roller shaft 600 M of the developing roller 6 M is inserted through the bearing 110 M. The developing roller shaft 600 M is made of metal. Because the bearing 110 M is in contact with the developing roller shaft 600 M, the developing electrode 103 M is electrically connected to the developing roller 6 M. With this configuration, the cartridge-side developing-bias contact 45 M of the shaft 109 M is electrically connected to the developing roller 6 M.

2.3 Detection Member

The detection member 104 M is mounted to the shaft 109 M so as to be rotatable around the shaft 109 M. The detection member 104 M includes gear teeth provided in a portion of the circumference of the detection member 104 M in a rotational direction thereof. More specifically, the detection member 104 M is a tooth-missing gear including a teeth portion 1040 M and a tooth-missing portion 1041 M. The teeth portion 1040 M includes gear teeth arranged in the rotational direction of the detection member 104 M. The tooth-missing portion 1041 M includes no gear teeth, and extends in the rotational direction of the detection member 104 M. The detection member 104 M receives drive force from the drive power source 211 to rotate, only while the teeth portion 1040 M is in meshingly engagement with the agitator gear 102 M.

The detection member 104 M includes a detecting protrusion 120 M which protrudes from the detection member 104 M in the developing-roller axial direction. The detecting protrusion 120 M extends also in the rotational direction of the detection member 104 M such that the detecting protrusion 120 M covers a portion of the circumferential surface of the shaft 109 M in the rotating direction of the detection member 104 M. The detecting protrusion 120 M is rotatable together with the detection member 104 M.

2.4 Cover

The cover 105 M is fixedly secured to the outer surface of the end wall 1010 M of the cartridge housing 101 M. The cover 105 M is for covering a portion of the detection member 104 M. More specifically, the cover 105 M has an opening 121 M, in which the detecting protrusion 120 M is inserted.

3. Detailed Description of the Cartridge Support Member

The cartridge support member 3 will now be described in detail with reference to FIGS. 2 to 7 .

As shown in FIGS. 2 and 3 , the cartridge support member 3 includes: a frame 11 ; a plurality of the levers 12 K, 12 Y, 12 M and 12 C; a plurality of the support-member-side developing-bias electrodes 13 K, 13 Y, 13 M and 13 C; a plurality of tension springs 14 K, 14 Y, 14 M and 14 C; a plurality of connecting members 15 K, 15 Y, 15 M and 15 C; a plurality of covers 16 K, 16 Y, 16 M and 16 C; and a plurality of lock mechanisms 63 K, 63 Y, 63 M and 63 C.

3.1 Frame

The frame 11 is configured to support the photosensitive drums 5 K, 5 Y, 5 M and 5 C therein and is further configured to guide the cartridges 4 K, 4 Y, 4 M and 4 C when the cartridges 4 K, 4 Y, 4 M and 4 C are attached to, or detached from, the cartridge support member 3 . The frame 11 includes a first wall 111 and a second wall 112 spaced apart from each other in the drum axial direction. Each of the first wall 111 and the second wall 112 extends in both of: the arrangement direction; and a cartridge attachment/detachment direction in which the cartridges 4 K, 4 Y, 4 M and 4 C are attached to, or detached from, the cartridge support member 3 . The cartridge attachment/detachment direction intersects with both of the drum-axial direction and the arrangement direction. More preferably, the cartridge attachment/detachment direction is perpendicular to the axial direction, and intersects with the arrangement direction. The first wall 111 supports one end of each of the photosensitive drums 5 K, 5 Y, 5 M and 5 C in the drum-axial direction, and the second wall 112 supports the other end of each of the photosensitive drums 5 K, 5 Y, 5 M and 5 C in the drum-axial direction. When the cartridges 4 K, 4 Y, 4 M and 4 C are supported in the cartridge support member 3 , the cartridges 4 K, 4 Y, 4 M and 4 C are positioned between the first wall 111 and the second wall 112 in the drum-axial direction.

As shown in FIGS. 3 and 4 , the first wall 111 includes a first surface S 1 and a second surface S 2 opposite to each other. In other words, the cartridge support member 3 includes the first surface S 1 and the second surface S 2 .

As shown in FIG. 4 , the first surface S 1 of the first wall 111 is positioned closer to the second wall 112 (see FIG. 2 ) than the second surface S 2 of the first wall 111 is to the second wall 112 . In other words, the first surface S 1 is an inward surface of the first wall 111 in the drum-axial direction. The first surface S 1 opposes the cartridges 4 K, 4 Y, 4 M and 4 C in the drum-axial direction when the cartridges 4 K, 4 Y, 4 M and 4 C are supported in the cartridge support member 3 . The first surface S 1 includes guides 113 K, 113 Y, 113 M and 113 C in correspondence with the cartridges 4 K, 4 Y, 4 M and 4 C, respectively. The guide 113 K is configured to guide the cartridge 4 K when the cartridge 4 K is inserted into, or pulled out of, the cartridge support member 3 . The guide 113 Y is configured to guide the cartridge 4 Y when the cartridge 4 Y is attached to, or detached from, the cartridge support member 3 . The guide 113 M is configured to guide the cartridge 4 M when the cartridge 4 M is attached to, or detached from, the cartridge support member 3 . The guide 113 C is configured to guide the cartridge 4 C when the cartridge 4 C is attached to, or detached from, the cartridge support member 3 . Each of the guides 113 K, 113 Y, 113 M and 113 C protrudes from the first surface S 1 of the first wall 111 inwardly in the drum-axial direction, and is elongated in the cartridge attachment/detachment direction. Each of the guides 113 K, 113 Y, 113 M and 113 C has an elongated plate shape.

As shown in FIG. 3 , the second surface S 2 of the first wall 111 is disposed at an opposite side of the second wall 112 with respect to the first surface S 1 of the first wall 111 in the drum-axial direction. In other words, the second surface S 2 of the first wall 111 is an outward surface of the first wall 111 in the drum-axial direction. When the cartridges 4 K, 4 Y, 4 M and 4 C are supported in the cartridge support member 3 , the second surface S 2 of the first wall 111 is disposed at the opposite side of the cartridges 4 K, 4 Y, 4 M and 4 C with respect to the first surface S 1 of the first wall 111 in the drum-axial direction.

As shown in FIG. 4 , the first wall 111 is formed with openings 24 K, 24 Y, 24 M, and 24 C that penetrate the first wall 111 at positions in correspondence with the levers 12 K, 12 Y, 12 M, and 12 C, respectively. That is, each of the openings 24 K, 24 Y, 24 M, and 24 C is formed at a position next to the corresponding guide 113 K, 113 Y, 113 M and 113 C in the arrangement direction.

As shown in FIG. 2 , the second wall 112 includes guides 114 K, 114 Y, 114 M and 114 C for guiding the cartridges 4 K, 4 Y, 4 M and 4 C, respectively. The guides 114 K, 114 Y, 114 M and 114 C are disposed on an inward surface of the second wall 112 in the drum-axial direction.

As shown in FIG. 4 , the lock mechanisms 63 K, 63 Y, 63 M and 63 C are provided on the first surface S 1 of the first wall 111 . The lock mechanism 63 K includes a first lock member 61 K and a second lock member 62 K. The lock mechanism 63 Y includes a first lock member 61 Y and a second lock member 62 Y. The lock mechanism 63 M includes a first lock member 61 M and a second lock member 62 M. The lock mechanism 63 C includes a first lock member 61 C and a second lock member 62 C. The lock mechanisms 63 K, 63 Y, 63 M and 63 C are configured to lock the cartridges 4 K, 4 Y, 4 M and 4 C, respectively, to the cartridge support member 3 .

The lock mechanisms 63 K, 63 Y, 63 M and 63 C have the same configuration with one another. Accordingly, configuration of the lock mechanism 63 C will be described below with reference to FIG. 6 . As shown in FIG. 6 , the first lock member 61 C and the second lock member 62 C are provided on the cartridge support member 3 such that the first lock member 61 C and the second lock member 62 C are spaced apart from each other in the arrangement direction. The first lock member 61 C is pivotally movable relative to the cartridge support member 3 in a direction to approach the second lock member 62 C and in another direction to move away from the second lock member 62 C. The first lock member 61 C is biased by a spring (not shown) to approach the second lock member 62 C.

Next will be described with reference to FIGS. 9 and 11 the manner how the cartridge 4 M is locked by the lock mechanism 63 M.

The cartridge 4 M is movable between a locked position (see FIG. 11 ) and an unlocked position (see FIG. 9 ) while the cartridge 4 M remains being supported by the cartridge support member 3 . When the cartridge 4 M is at the locked position, the cartridge 4 M is locked to the cartridge support member 3 . More specifically, the cartridge 4 M is locked to the cartridge support member 3 by the boss 108 M of the cartridge 4 M being clamped between the first lock member 61 M and the second lock member 62 M as shown in FIG. 11 . The locked state of the cartridge 4 M relative to the cartridge support member 3 is released when the cartridge 4 M moves to the unlocked position. More precisely, as shown in FIG. 9 , the locked state of the cartridge 4 M with respect to the cartridge support member 3 is released when the boss 108 M of the cartridge 4 M moves out of the gap between the first lock member 61 M and the second lock member 62 M.

As shown in FIGS. 2 and 3 , on the second surface S 2 of the first wall 111 , there are provided: the support-member-side developing-bias electrodes 13 K, 13 Y, 13 M and 13 C; the tension springs 14 K, 14 Y, 14 M and 14 C; the levers 12 K, 12 Y, 12 M and 12 C; the connecting members 15 K, 15 Y, 15 M and 15 C; and the covers 16 K, 16 Y, 16 M and 16 C.

3.2 Levers

As shown in FIG. 3 , the levers 12 K, 12 Y, 12 M and 12 C are pivotally movably supported by the first wall 111 . Because the levers 12 K, 12 Y, 12 M and 12 C are provided on the second surface S 2 that is opposite to the first surface S 1 on which the guides 113 K, 113 Y, 113 M and 113 C are provided, it is ensured that the levers 12 K, 12 Y, 12 M and 12 C will not interfere with the cartridges 4 K, 4 Y, 4 M and 4 C when the cartridges 4 K, 4 Y, 4 M and 4 C are attached to, or detached from, the cartridge support member 3 . The levers 12 K, 12 Y, 12 M and 12 C are arranged in the arrangement direction with intervals therebetween.

The levers 12 K, 12 Y, 12 M and 12 C have the same configuration with one another. Therefore, the lever 12 M will be described below as a representative example of the levers 12 K, 12 Y, 12 M and 12 C.

3.2.1 Position of the Lever

The lever 12 M can be located at either one of: a first position ( FIG. 12 ); a second position ( FIG. 14 ); a third position ( FIG. 7 ); and a fourth position ( FIG. 10 ), which are different from one another.

More specifically, while the cartridge 4 M is not supported by the cartridge support member 3 , the lever 12 M stays at the third position due to the pulling force of the tension spring 14 M as shown in FIG. 7 . When the cartridge 4 M becomes supported by the cartridge support member 3 and disposed at the unlocked position, the lever 12 M moves from the third position to the fourth position shown in FIG. 10 upon abutment contact with the shaft 109 M of the cartridge 4 M. While the cartridge 4 M remains supported by the cartridge support member 3 , when the cartridge 4 M moves from the unlocked position to the locked position, the lever 12 M moves from the fourth position to the first position shown in FIG. 12 , while maintaining the contact with the shaft 109 M. While the cartridge 4 M remains supported by the cartridge support member 3 and stays at the locked position, when the detecting protrusion 120 M of the cartridge 4 M is brought into abutment contact with the lever 12 M, the lever 12 M moves from the first position to the second position shown in FIG. 14 .

3.2.2 Structure of the Lever

As shown in FIGS. 5 and 7 , the lever 12 M includes: a lever body 25 M; and an electrode 23 M. The lever body 25 M is pivotally movably supported by the frame 11 . In other words, the lever 12 M is pivotally movably supported by the frame 11 . More specifically, the cartridge support member 3 includes a boss 21 M having a cylindrical shape protruding from the second surface S 2 in the drum-axial direction. The lever body 25 M extends in the radius direction of the boss 21 M and along the second surface S 2 of the first wall 111 . The lever body 25 M includes a base end 31 M and a distal end 32 M in the direction in which the lever body 25 M extends such that the distal end 32 M is apart from the base end 31 M in the direction the lever body 25 M extends. The lever body 25 M is attached, at the base end 31 M, to the boss 21 M such that the lever 12 M is pivotally movable about the boss 21 M. When the lever 12 M pivotally moves, the distal end 32 M of the lever 12 M moves in the arrangement direction. The lever body 25 M is formed of electrically insulating material such as resin. The lever body 25 M includes a protrusion 22 M at the distal end 32 M as shown in FIG. 6 . The protrusion 22 M protrudes from the distal end 32 M of the lever body 25 M, which is disposed at the second surface S 2 side of the first wall 111 , inward in the drum-axial direction. The protrusion 22 M is inserted into the opening 24 M of the first wall 111 to reach a position further inward of the first surface S 1 of the first wall 111 in the drum-axial direction. A portion of the protrusion 22 M that is disposed further inward of the first surface S 1 of the first wall 111 in the drum-axial direction therefore opposes the guide 113 M in the arrangement direction.

As shown in FIGS. 5 and 6 , the electrode 23 M is attached to the distal end 32 M of the lever body 25 M such that a portion of the electrode 23 M is disposed on the protrusion 22 M. The electrode 23 M is a bent wire formed of electrically conductive material such as metal. As shown in FIGS. 9-12 , the part of the electrode 23 M that is disposed on the protrusion 22 M contacts the circumferential surface of the shaft 109 M of the cartridge 4 M when the cartridge 4 M is inserted into the cartridge support member 3 . The part of the electrode 23 M that contacts the shaft 109 M serves as a lever-side developing-bias contact 41 M. The portion of the circumferential surface of the shaft 109 M that contacts the electrode 23 M serves as the cartridge-side developing-bias contact 45 M. Thus, the lever-side developing-bias contact 41 M and the cartridge-side developing-bias contact 45 M are configured so as to be electrically connected with each other.

Further, as shown in FIG. 14 , when the cartridge 4 M supported in the cartridge support member 3 becomes disposed at the locked position, the electrode 23 M is brought into abutment contact with the connecting member 15 M at a portion of the electrode 23 M that is different from the lever-side developing-bias contact 41 . That is, when the lever 12 M becomes disposed at the second position, the electrode 23 M contacts the connecting member 15 M at a portion of the electrode 23 M that is different from the lever-side developing-bias contact 41 M. The portion of the electrode 23 M that contacts the connecting member 15 M serves as the support-member-side detection contact 42 M. Namely, the electrode 23 M includes both of the lever-side developing-bias contact 41 M and the support-member-side detection contact 42 M. In other words, the lever 12 M includes both of the lever-side developing-bias contact 41 M and the support-member-side detection contact 42 M.

3.3 Support-Member-Side Developing-Bias Electrodes

As shown in FIGS. 2 and 3 , the support-member-side developing-bias electrodes 13 K, 13 Y, 13 M and 13 C are fixedly secured to the second surface S 2 of the first wall 111 in the frame 11 such that the support-member-side developing-bias electrodes 13 K, 13 Y, 13 M and 13 C are arranged in the arrangement direction with intervals therebetween. While the cartridge support member 3 remains at the inside position, the support-member-side developing-bias electrode 13 K remains in contact with the main-body-side developing-bias contact 201 K so as to be in electrical connection with the main-body-side developing-bias contact 201 K, the support-member-side developing-bias electrode 13 Y remains in contact with the main-body-side developing-bias contact 201 Y so as to be in electrical connection with the main-body-side developing-bias contact 201 Y, the support-member-side developing-bias electrode 13 M remains in contact with the main-body-side developing-bias contact 201 M so as to be in electrical connection with the main-body-side developing-bias contact 201 M, and the support-member-side developing-bias electrode 13 C remains in contact with the main-body-side developing-bias contact 201 C so as to be in electrical connection with the main-body-side developing-bias contact 201 C.

The support-member-side developing-bias electrodes 13 K, 13 Y, 13 M and 13 C have the same structure with one another. Therefore, the support-member-side developing-bias electrode 13 M will be described below as a representative example of the support-member-side developing-bias electrodes 13 K, 13 Y, 13 M and 13 C.

As shown in FIGS. 5 and 7 , the support-member-side developing-bias electrode 13 M is disposed at an opposite side of the connecting member 15 M with respect to the lever 12 M in the arrangement direction. The support-member-side developing-bias electrode 13 M is a bent wire formed of electrically conductive material such as metal. The support-member-side developing-bias electrode 13 M includes an electric contact 43 M. While the cartridge support member 3 remains at the inside position, the electric contact 43 M remains in contact with the main-body-side developing-bias contact 201 M, thereby maintaining electrical connection with the main-body-side developing-bias contact 201 M.

3.4 Tension Springs

As shown in FIG. 3 , the tension springs 14 K, 14 Y, 14 M and 14 C are provided on the second surface S 2 of the frame 11 such that the tension springs 14 K, 14 Y, 14 M and 14 C are arranged in the arrangement direction with intervals therebetween.

As shown in FIG. 3 , the tension springs 14 K, 14 Y, 14 M and 14 C have the same configuration with one another. Therefore, the tension spring 14 M will be described below as a representative example of the tension springs 14 K, 14 Y, 14 M and 14 C.

As shown in FIGS. 5 and 7 , the tension spring 14 M is disposed at a position between the support-member-side developing-bias electrode 13 M and the lever 12 M in the arrangement direction. The tension spring 14 M extends in the arrangement direction. The tension spring 14 M is made of electrically conductive material such as metal. As shown in FIG. 7 , the tension spring 14 M includes a first end 51 M and a second end 52 M spaced apart from each other in the arrangement direction. The tension spring 14 M is connected at the first end 51 M to the support-member-side developing-bias electrode 13 M. That is, the first end 51 M of the tension spring 14 M is attached to the frame 11 via the support-member-side developing-bias electrode 13 M. The tension spring 14 M is connected at the second end 52 M to the electrode 23 M of the lever 12 M. That is, the tension spring 14 M is in contact with the support-member-side developing-bias electrode 13 M at the first end 51 M thereof, and is in contact with the electrode 23 M at the second end 52 M thereof. The tension spring 14 M thus electrically connects the support-member-side developing-bias electrode 13 M to the electrode 23 M of the lever 12 M. The distance between the first end 51 M and the second end 52 M of the tension spring 14 M when the lever 12 M is at the second position (D 2 in FIG. 14 ) is longer than the distance between the first end 51 M and the second end 52 M of the tension spring 14 M when the lever 12 M is at the first position (D 1 in FIG. 12 ). Further, the distance between the first end 51 M and the second end 52 M of the tension spring 14 M when the lever 12 M is at the third position (D 3 in FIG. 7 ) is shorter than the distance between the first end 51 M and the second end 52 M of the tension spring 14 M when the lever 12 M is at the first position (D 1 in FIG. 12 ). Moreover, the distance between the first end 51 M and the second end 52 M of the tension spring 14 M when the lever 12 M is at the fourth position (D 4 in FIG. 10 ) is longer than the distance between the first end 51 M and the second end 52 M of the tension spring 14 M when the lever 12 M is at the second position (D 2 in FIG. 14 ).

3.5 Connecting Members

As shown in FIGS. 2 and 3 , the connecting members 15 K, 15 Y, 15 M and 15 C are provided on the second surface S 2 of the first wall 111 such that the connecting members 15 K, 15 Y, 15 M and 15 C are arranged in the arrangement direction with intervals therebetween.

While the cartridge support member 3 remains at the inside position, the connecting member 15 K is in contact with the main-body-side detection contact 202 K so as to be in electrical connection with the main-body-side detection contact 202 K, the connecting member 15 Y is in contact with the main-body-side detection contact 202 Y so as to be in electrical connection with the main-body-side detection contact 202 Y, the connecting member 15 M is in contact with the main-body-side detection contact 202 M so as to be in electrical connection with the main-body-side detection contact 202 M, and the connecting member 15 C is in contact with the main-body-side detection contact 202 C so as to be in electrical connection with the main-body-side detection contact 202 C. The detector 203 detects that the main-body-side detection contact 202 K is electrically connected to the support-member-side detection contact 42 K when an electric current flows in the main-body-side detection contact 202 K. The detector 203 detects that the main-body-side detection contact 202 Y is electrically connected to the support-member-side detection contact 42 Y when an electric current flows in the main-body-side detection contact 202 Y. The detector 203 detects that the main-body-side detection contact 202 M is electrically connected to the support-member-side detection contact 42 M when an electric current flows in the main-body-side detection contact 202 M. The detector 203 detects that the main-body-side detection contact 202 C is electrically connected to the support-member-side detection contact 42 C when an electric current flows in the main-body-side detection contact 202 C.

As shown in FIG. 3 , the connecting members 15 K, 15 Y, 15 M and 15 C have the same structure with one another. Therefore, the lever 15 M will be described below as a representative example of the connecting members 15 K, 15 Y, 15 M and 15 C.

As shown in FIGS. 5 and 7 , the connecting member 15 M is disposed at an opposite side of the tension spring 14 M with respect to the lever 12 M in the attachment direction. The connecting member 15 M is a bent wire formed of electrically conductive material such as metal. The connecting member 15 M includes: a connection part 26 M; a first part 27 M; and a second part 28 M.

The connection part 26 M connects the first part 27 M and second part 28 M with each other. The connection part 26 M has a cylindrical shape whose axis extends in the drum-axial direction. More specifically, the connection part 26 M is a coil formed of a spiral wire.

The first part 27 M and the second part 28 M are arranged in the arrangement direction, that is, in a direction in which the lever 12 M moves (which will be referred to also as “lever-moving direction” hereinafter). The first part 27 M and the second part 28 M are spaced apart from each other in the arrangement direction, that is, in the lever-moving direction. The first part 27 M is disposed at an opposite side of the lever 12 M with respect to the second part 28 M in the arrangement direction, that is, in the lever-moving direction.

The first part 27 M of the connecting member 15 M is fixedly secured to the frame 11 such that the first part 27 M extends in a direction intersecting with the lever-moving direction. The first part 27 M includes a base end and a distal end spaced apart from each other in a direction in which the first part 27 M extends. The first part 27 M is connected, at its base end, to the connection part 26 M. The first part 27 M is in contact with the main-body-side detection contact 202 M at its distal end, while the cartridge support member 3 remains at the inside position. The first part 27 M includes an electric contact 44 M at its distal end. The electric contact 44 M remains in contact with the main-body-side detection contact 202 M, while the cartridge support member 3 stays at the inside position. Thus, the connecting member 15 M is in electrical connection with the main-body-side detection contact 202 M, while the cartridge support member 3 stays at the inside position.

The second part 28 M of the connecting member 15 M is disposed between the lever 12 M and the first part 27 M of the connecting member 14 M in the lever-moving direction. The second part 28 M extends in a direction intersecting with the lever-moving direction. The second part 28 M includes a base end and a distal end spaced apart from each other in the direction in which the second part 28 M extends. The second part 28 M is connected at its base end to the connection part 26 M. In this manner, the base end of the second part 28 M is connected to the base end of the first part 27 M via the connection part 26 M. The distal end of the second part 28 M is spaced away from the distal end of the first part 27 M in the lever-moving direction. As shown in FIGS. 12 and 14 , the second part 28 M of the connecting member 15 is movable such that the distal end of the second part 28 M approaches the first part 27 M in the lever-moving direction. More specifically, the second part 28 M of the connecting member 15 moves in the lever-moving direction to approach the first part 27 M when the electrode 23 M of the lever 12 M is brought into abutment contact with the second part 28 M of the connecting member 15 . In other words, the second part 28 M moves in the lever-moving direction to approach the first part 27 M when the electrode 23 M of the lever 12 M is brought into contact with the second part 28 M. The connecting member 15 M is deformed resiliently when the second part 28 M of the connecting member 15 approaches the first part 27 M of the connecting member 15 . When the electrode 23 M is separated away from the connecting member 15 M, the connecting member 15 restores its original shape by virtue of its internal stress. Thus, the connecting member 15 M serves as a wired spring.

Also when the electrode 23 M is brought into abutment contact with the second part 28 M of the connecting member 15 M, the connecting member 15 M becomes electrically connected to the support-member-side developing-bias electrode 13 M via the tension spring 14 M and the electrode 23 M of the lever 12 M.

3.6 Covers

As shown in FIGS. 2 and 3 , the covers 16 K, 16 Y, 16 M and 16 C are fixedly secured to the second surface S 2 of the first wall 111 . The covers 16 K, 16 Y, 16 M and 16 C are arranged in the arrangement direction.

The cover 16 K is disposed such that the support-member-side developing-bias electrode 13 K, the tension spring 14 K, the lever 12 K, and the connecting member 15 K are interposed between the second surface S 2 of the first wall 111 and the cover 16 K in the drum-axial direction. The cover 16 K covers the entire part of the tension spring 14 K, and covers the entire part of the lever 12 K. The cover 16 K covers only a portion of the support-member-side developing-bias electrode 13 K, and covers only a portion of the connecting member 15 K. More specifically, as shown in FIG. 2 , the cover 16 K has: an opening exposing the electric contact 43 K of the support-member-side developing-bias electrode 13 K; and an opening exposing the electric contact 44 K of the connecting member 15 M.

The cover 16 Y is disposed such that the support-member-side developing-bias electrode 13 Y, the tension spring 14 Y, the lever 12 Y, and the connecting member 15 Y are interposed between the second surface S 2 of the first wall 111 and the cover 16 Y in the drum-axial direction. The cover 16 Y covers the entire part of the tension spring 14 Y, and covers the entire part of the lever 12 Y. The cover 16 Y covers only a portion of the support-member-side developing-bias electrode 13 Y, and covers only a portion of the connecting member 15 Y. More specifically, as shown in FIG. 2 , the cover 16 Y has: an opening exposing the electric contact 43 Y of the support-member-side developing-bias electrode 13 Y; and an opening exposing the electric contact 44 Y of the connecting member 15 Y.

The cover 16 M is disposed such that the support-member-side developing-bias electrode 13 M, the tension spring 14 M, the lever 12 M, and the connecting member 15 M are interposed between the second surface S 2 of the first wall 111 and the cover 16 M in the drum-axial direction. The cover 16 M covers the entire part of the tension spring 14 M, and covers the entire part of the lever 12 M. The cover 16 M covers only a portion of the support-member-side developing-bias electrode 13 M, and covers only a portion of the connecting member 15 M. More specifically, as shown in FIG. 2 , the cover 16 M has: an opening exposing the electric contact 43 M of the support-member-side developing-bias electrode 13 M; and an opening exposing the electric contact 44 M of the connecting member 15 M.

The cover 16 C is disposed such that the support-member-side developing-bias electrode 13 C, the tension spring 14 C, the lever 12 C, and the connecting member 15 C are interposed between the second surface S 2 of the first wall 111 and the cover 16 C in the drum-axial direction. The cover 16 C covers the entire of the tension spring 14 C, and covers the entire of the lever 12 C. The cover 16 C covers only a portion of the support-member-side developing-bias electrode 13 C, and covers only a portion of the connecting member 15 C. More specifically, as shown in FIG. 2 , the cover 16 C has: an opening exposing the electric contact 43 C of the support-member-side developing-bias electrode 13 C; and an opening exposing the electric contact 44 C of the connecting member 15 C.

Because the covers 16 K, 16 Y, 16 M and 16 C partially cover the corresponding connecting members 15 K, 15 Y, 15 M and 15 C, respectively, this reduces the possibility that the connecting members 15 K, 15 Y, 15 M and 15 C interfere with the main-body-side detection contacts 202 K, 202 Y, 202 M and 202 C during the process of moving the cartridge support member 3 between the inside position and the outside position.

4. Insertion of the Cartridge into the Cartridge Support Member

Next will be described, with reference to FIGS. 7 and 9 to 12 , how the cartridge 4 M is attached to the cartridge support member 3 . Note that the other remaining cartridges 4 K, 4 Y and 4 C are attached to the cartridge support member 3 in the same manner as the cartridge 4 M is. Thus, the insertion of the cartridge 4 M to the cartridge support member 3 will be described below.

While the cartridge 4 M is not supported in the cartridge support member 3 , the lever 12 M stays at the third position as shown in FIG. 7 . While staying at the third position, the lever 12 M is located apart from the connecting member 15 M.

While the cartridge support member 3 remains at the outside position, the user attaches the cartridge 4 M to the cartridge support member 3 . As a result, the cartridge 4 M becomes disposed at the unlocked position with respect to the cartridge support member 3 as shown in FIG. 9 . The circumferential surface of the shaft 109 M of the cartridge 4 M is brought into abutment contact with the lever 12 M, whereupon the lever 12 M moves from the third position to the fourth position shown in FIG. 10 . When the lever 12 M reaches the fourth position, the lever 12 M is brought into abutment contact with the second part 28 M of the connecting member 15 M. The connecting member 15 M is deformed such that the second part 28 M of the connecting member 15 M approaches the first part 27 M of the connecting member 15 M.

That is, when the user attaches the cartridge 4 M to the cartridge support member 3 , the lever 12 M and the connecting member 15 M interfere with each other. The connecting member 15 M is configured such that the distal end of the second part 28 M functions as a free end and the second part 28 M is movable so as to approach the first part 27 M. Accordingly, this configuration can prevent the connecting member 15 M from being broken during the process of attaching the cartridge 4 M to the cartridge support member 3 .

While the cartridge support member 3 remains at the outside position, the user moves the cartridge 4 M from the unlocked position to the locked position shown in FIG. 11 . The shaft 109 M of the cartridge 4 M moves in a direction away from the connecting member 15 M. In association with this movement of the shaft 109 M, the lever 12 M is pulled by the tension spring 14 M to move in the direction away from the connecting member 15 M as shown in FIG. 12 , while maintaining the contact with the shaft 109 M. As a result, the lever 12 M moves from the fourth position to the first position.

In this state, the user moves the cartridge support member 3 from the outside position toward the inside position. When the cartridge support member 3 reaches the inside position, the electric contact 43 M of the support-member-side developing-bias electrode 13 M is brought into contact with the main-body-side developing-bias contact 201 M so as to be electrically connected to the main-body-side developing-bias contact 201 M. In this way, when the cartridge support member 3 having the cartridge 4 M held therein reaches the inside position, the lever 12 M electrically connects the main-body-side developing-bias contact 201 M to the cartridge-side developing-bias contact 45 M. The developing bias is applied from the main-body-side developing-bias contact 201 M to the shaft 109 M of the cartridge 4 M through the support-member-side developing-bias electrode 13 M, tension spring 14 M and electrode 23 M. It is noted that the electric contact 44 M of the connecting member 15 M is electrically connected with the main-body-side detection contact 202 M. However, as long as the lever 12 M stays at the first position, the support-member-side detection contact 42 M is not electrically connected with the main-body-side detection contact 202 M because the lever 12 M at the first position is disposed apart from the connecting member 15 M.

It is also noted that the main-body-side developing-bias contact 201 M and the cartridge-side developing-bias contact 45 M are indispensable for applying the developing bias to the developing roller 6 M. By employing the configuration that the lever 12 M electrically connects the main-body-side developing-bias contact 201 M to the cartridge-side developing-bias contact 45 M, the developing bias applied from the main-body-side developing-bias contact 201 M can be utilized by the detector 203 to detect whether the support-member-side detection contact 42 M is electrically connected with the main-body-side detection contact 202 M. Hence, no additional power supplies need to be provided to detect the electrical connection between the support-member-side detection contact 42 M and the main-body-side detection contact 202 M.

5. Operation of the Image Forming Apparatus

Next will be described with reference to FIGS. 11 to 14 how the image forming apparatus 1 operates.

While the cartridge support member 3 is at the inside position with the cartridges 4 K, 4 Y, 4 M and 4 C being held in the cartridge support member 3 at the locked position as shown in FIGS. 11 and 12 , the image forming apparatus 1 reads information on the cartridges 4 K, 4 Y, 4 M and 4 C. The information on the cartridges 4 K, 4 Y, 4 M and 4 C is read in the same manner as one another. Therefore, next will be described how information is read from the cartridge 4 M.

To read information from the cartridge 4 M, a drive force is inputted from the drive power source 211 through the main-body-side coupling 210 M to the coupling 107 M of the cartridge 4 M (see FIG. 8 ). The detecting protrusion 120 M is rotated around the shaft 109 M by the drive force inputted from the drive power source 211 .

As a result, as shown in FIG. 13 , the detecting protrusion 120 M is brought into abutment contact with the lever 12 M that is disposed in the first position. In other words, the detecting protrusion 120 M contacts the protrusion 22 M of the lever 12 M. As a result, as shown in FIG. 14 , the lever 12 M receives the drive force from the detection member 104 M to move from the first position to the second position. Thus, the lever 12 M moves from the first position to the second position by the drive force transmitted from the detection member 104 M, while the cartridge support member 3 stays at the inside position with the cartridge 4 M being held therein. It is noted that the lever 12 M is capable of moving between the first position and the second position by the drive force transmitted from the detection member 104 M, while the cartridge support member 3 stays at the inside position with the cartridge 4 M being held therein. Thus, the detecting protrusion 120 M serves as a cam that rotates around the shaft 109 M to move the lever 12 M.

The detecting protrusion 120 M becomes interposed between the electrode 23 M of the lever 12 M and the shaft 109 M, thereby electrically disconnecting the electrode 23 M from the shaft 109 M and electrically connecting the electrode 23 M to the second part 28 M of the connecting member 15 M. Thus, when the lever 12 M reaches the second position, the support-member-side detection contact 42 M becomes electrically connected with the main-body-side detection contact 202 M. To summarize, the connecting member 15 M electrically connects the support-member-side detection contact 42 M to the main-body-side detection contact 202 M when the lever 12 M reaches the second position while the cartridge support unit 3 is at the inside position.

As a result, the developing bias is applied from the main-body-side developing-bias contact 201 M to the main-body-side detection contact 202 M through the support-member-side developing-bias electrode 13 M, tension spring 14 M, electrode 23 M and connecting member 15 M.

Accordingly, the detector 203 detects that the main-body-side detection contact 202 M is electrically connected with the support-member-side detection contact 42 M when the lever 12 M has reached the second position.

When the detecting protrusion 120 M further rotates, the detecting protrusion 120 M moves away from the protrusion 22 M of the lever 12 M. Thereafter, the teeth portion 1040 M of the detection member 104 M becomes disengaged from the agitator gear 102 M, whereupon the detection member 104 M stops rotating. The detecting protrusion 120 M also stops rotating.

When the detecting protrusion 120 M becomes separated away from the protrusion 22 M of the lever 12 M, the lever 12 M is pulled by the tension spring 14 M in the direction away from the connecting member 15 M, thereby moving back to the first position as illustrated in FIG. 12 .

As a result, the electrode 23 M of the lever 12 M becomes separated away from the connecting member 15 M, thereby electrically disconnecting the support-member-side detection contact 42 M from the main-body-side detection contact 202 M. The electrode 23 M of the lever 12 M is brought back into contact with the shaft 109 M, thereby applying the developing bias to the shaft 109 M.

The image forming apparatus 1 determines that the cartridge 4 M is a new product in a case where the detector 203 detects that the main-body-side detection contact 202 M is electrically connected with support-member-side detection contact 42 M while the information on the cartridges 4 K, 4 Y, 4 M and 4 C is being read.

The image forming apparatus 1 determines that the cartridge 4 M is a used cartridge in a case where the detector 203 does not detect that the main-body-side detection contact 202 M is electrically connected with the support-member-side detection contact 42 M while the information on the cartridges 4 K, 4 Y, 4 M and 4 C is being read.

Thereafter, the image forming apparatus 1 terminates the process of reading the information from the cartridges 4 K, 4 Y, 4 M and 4 C.

Whether the cartridge 4 M is a new one or a used one is an example of information on the cartridge 4 M. The pattern defined by the length of time, during which the main-body-side detection contact 202 M and support-member-side detection contact 42 M are in electrical connection with each other, and the number of times, by which the main-body-side detection contact 202 M and the support-member-side detection contact 42 M are brought into electrical connection with each other, can be associated with not only the data indicating whether the cartridge 4 M is a new one or a used one, but also data indicating how many sheets can be printed with the toner contained in the cartridge 4 M. The length of time, during which the main-body-side detection contact 202 M and the support-member-side detection contact 42 M have been in electrical connection with each other, and the number of times, by which the main-body-side detection contact 202 M and the support-member-side detection contact 42 M have been brought into electrical connection with each other, can be adjusted by modifying the shape of the detecting protrusion 120 M.

6. Functions

In the image forming apparatus 1 , when the cartridge support member 3 is disposed at the inside position with the cartridge 4 M being held therein, as shown in FIGS. 11 to 14 , the detecting protrusion 120 M is brought into abutment contact with the lever 12 M, whereupon the lever 12 M moves from the first position to the second position by the drive force received from the detection member 104 M. The detector 203 detects that the main-body-side detection contact 202 M and the support-member-side detection contact 42 M are brought into electrical connection with each other when the lever 12 M has reached the second position.

Hence, although no photo-sensors are additionally provided in the housing 2 of the image forming apparatus 1 for the purpose of detecting the motion of the lever 12 M, the detector 203 can detect that the lever 12 M moves by detecting that the main-body-side detection contact 202 M is electrically connected with the support-member-side detection contact 42 M.

The image forming apparatus 1 can be made smaller than in the case where a photo-sensor is additionally provided in the housing 2 for the detection of the motion of the lever 12 M.

7. Modifications

Each of the levers 12 K, 12 Y, 12 M and 12 C may be made of electrically conductive material in its entirety. Alternatively, each of the levers 12 K, 12 Y, 12 M and 12 C may be made, in part, of electrically conductive material. The electrically conductive material may be an electrically conductive resin.

Further, the detection member 104 M may be configured to move linearly upon receipt of the drive force from the drive power source 211 . In the embodiment, the detecting protrusion 120 M is formed integrally with the detection member 104 M. That is, the detection member 104 M and the detecting protrusion 120 M constitute a single component. However, the detecting protrusion 120 M may be prepared as a component separate from the detection member 104 M, and be attached to the detection member 104 M.

In the embodiment described above, the covers 16 K, 16 Y, 16 M and 16 C for the respective colors are provided as separate components. Instead, the covers 16 K, 16 Y, 16 M and 16 C may be integrated into a single component.

In the above-described embodiment, the cartridge support member 3 is a drum unit that is provided with the plurality of photosensitive drums 5 K, 5 Y, 5 M and 5 C. Instead, the cartridge support member 3 may be provided with no photosensitive drums. In such a case, the developer cartridges 4 K, 4 Y, 4 M and 4 C are additionally provided with the photosensitive drums 5 K, 5 Y, 5 M and 5 C, respectively.

While the description has been made in detail with reference to specific embodiment thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the above described aspects.