Image forming apparatus including a transfer belt unit, image forming units, a support member, an air flow path forming member, and an exhausting unit

An image forming apparatus includes: a transfer belt having a surface onto which a toner image is transferred directly or through a transfer medium; plural image forming units that are aligned along a moving direction of the surface of the transfer belt and form the toner image; a support member that supports the transfer belt; a flow path forming member that forms a flow path along the moving direction of the surface of the transfer belt, has plural suction ports through which floating fine toner particles occurring in the plural image forming units are sucked into the flow path, and is disposed at the transfer belt side with respect to the support member; and an exhausting unit that sucks the floating fine toner particles through the suction ports into the flow path, and exhausts the sucked floating fine toner particles from the flow path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-161960 filed Jul. 8, 2009.

BACKGROUND

Technical Field

SUMMARY

According to an aspect of the present invention, there is provided an image forming apparatus including: a transfer belt unit that includes a transfer belt, the transfer belt having a surface onto which a toner image is transferred directly or through a transfer medium; a plurality of image forming units that are aligned along a moving direction of the surface of the transfer belt and form the toner image; a support member that supports the transfer belt unit; an air flow path forming member that forms an air flow path along the moving direction of the surface of the transfer belt, has a plurality of suction ports which are sucked into the air flow path, and is disposed at the transfer belt unit side with respect to the support member; and an exhausting unit that exhausts from the air flow path.

DETAILED DESCRIPTION

An image forming apparatus according to an exemplary embodiment of the present invention will be described with reference toFIGS. 1 to 15.

As shown inFIG. 4, the image forming apparatus10according to the exemplary embodiment of the present invention includes an automatic document feeder12for automatically feeding plural original documents G one by one, a platen glass16on which the original document G is put, and a document reading device14for reading the original document G fed by the automatic document feeder12or the original document G put on the platen glass16that are disposed at the upper portion of the main body10A of the apparatus. An arrow UP inFIG. 4represents an upward direction in the vertical direction, and an arrow FR represents an frontward direction (to a front side at which a user stands) (seeFIGS. 4 and 5).

The document reading device14is equipped with a light source18for irradiating the original document G fed by the automatic document feeder12or the original document G put on the platen glass16with light.

The document reading device14is further equipped with an optical system including a full-rate mirror20for reflecting, in a direction parallel to the platen glass16, reflection light that is reflected from the original document G when the original document G is irradiated with light from the light source18, a half-rate mirror22for downwardly reflecting the reflection light reflected from the full-rate mirror20, a half-rate mirror24for reflecting the reflection light reflected from the half-rate mirror22in a direction parallel to the platen glass16so that the reflection light from the half-rate mirror22is folded back, and an imaging lens26to which the reflection light folded back by the half-rate mirror24is incident.

The document reading device14is further provided with a photoelectric transducer28for converting the reflection light image-formed by the imaging lens26to an electrical signal, and an image processing apparatus29for executing image processing on the electrical signal converted by the photoelectric transducer28.

The light source18, the full-rate mirror20, the half-rate mirror22and the half-rate mirror24are movable along the platen glass16. When an original document G put on the platen glass16is read, the light source18irradiates the original document G put on the platen glass16with light and reflection light reflected from the original document G forms an image on the photoelectric transducer28while the light source18, the full-rate mirror20, the half-rate mirror22and the half-rate mirror24are moved.

Furthermore, when an original document G fed from the automatic document feeder12is read, the light source18, the full-rate mirror20, the half-rate mirror22and the half-rate mirror24are stopped at respective predetermined positions, the original document G fed from the automatic document feeder12is irradiated with light by the light source18, and reflection light reflected from the original document G forms an image on the photoelectric transducer28.

Plural image forming units30as an example of an image forming section for forming respective toner images of different colors are arranged side by side at the center portion in the vertical direction of the main body10A of the apparatus so as to be inclined with respect to the horizontal direction. Furthermore, a transfer belt unit including an endless intermediate transfer belt32as an example of a transfer belt is provided at the upper side of the image forming units30. Respective color toner images formed by the respective image forming units30are transferred onto the endless intermediate transfer belt32while the endless intermediate transfer belt32is driven to be circulated in the direction of an arrow A inFIG. 4.

More specifically, four image forming units30Y,30M,30C and30K of yellow (Y), magenta (M), cyan (C) and black (K) are disposed in this order as shown inFIG. 3. The image forming unit30Y for forming a toner image of yellow (Y) that is first transferred onto the intermediate transfer belt32is disposed at the highest position, and the image forming unit30K for forming a toner image of black (K) that is finally transferred onto the intermediate transfer belt32is disposed at the lowest position. The image forming units30Y,30M,30C and30K are arranged so as to be spaced from one another at a fixed interval while tilted obliquely to the horizontal direction at only a predetermined angle as a whole.

These four image forming units30Y,30M,30C and30K basically have the same configuration. In the following description, when the respective colors are discriminated from one another, characters (Y, M, C, K) corresponding to the respective colors are affixed to reference numerals, and when the respective colors are not particularly discriminated from one another, the characters corresponding to the respective colors are omitted.

As shown inFIG. 2, the image forming unit30of each color is provided with an image carrier34rotated in the direction of an arrow D by a driving unit (not shown), and further provided with a charging member36for uniformly electrifying the surface of the image carrier34.

An exposure device40for applying light corresponding to a predetermined color to the surface of the image carrier34which has been uniformly charged by the charging member36to form an electrostatic latent image is provided at the downstream side in the rotational direction of the image carrier34with respect to the charging member36. A developing unit42as an example of a developing member for developing the electrostatic latent image formed on the surface of the image carrier34with a toner of a predetermined color to visualize the electrostatic latent image as a toner image is also provided at the downstream side in the rotational direction of the image carrier34with respect to the exposure device40.

A primary transfer member46for transferring the toner image formed on the surface of the image carrier34onto the intermediate transfer belt32is provided at the opposite side to the image carrier34so that the intermediate transfer belt32is sandwiched between the image carrier34and the primary transfer member46. Furthermore, a cleaning device44for cleaning residual toner which is not transferred from the image carrier34to the intermediate transfer belt32and thus remains on the surface of the image carrier34, etc. is provided at the downstream side in the rotational direction of the image carrier34with respect to the primary transfer member46so as to be in contact with the surface of the image carrier34.

That is, the image forming unit30is configured to include the image carrier34, the charging member36, the exposure device40, the developing unit42and the cleaning device44.

Toner cartridges38Y,38M,38C,38K (seeFIG. 4) for supplying toners of predetermined colors to the developing units42of respective colors of yellow (Y), magenta (M), cyan (c), black (K) are provided above the intermediate transfer belt32. The toner cartridge38K in which the toner of the black (K) color is stocked is frequently used, and thus it is designed to be larger than the toner cartridges of the other colors.

In the above configuration, image data of the respective colors are successively output from the image processing device29or an outside source to the exposure devices40Y,40M,40C and40K that are individually provided to the image forming units30Y,30M,30C and30K of the respective colors of yellow (Y), magenta (M), cyan (C) and black (K). The surface of each image carrier34is exposed to light emitted corresponding to the image data from corresponding one of the exposure devices40Y,40M,40C and40K, and an electrostatic latent image is formed on the surface of the image carrier34. The electrostatic latent images formed on the surfaces of the image carriers34are developed into toner images of the respective colors of yellow (Y), magenta (M), cyan (C) and black (K) by the developing units42Y,42M,42C and42K, respectively.

The toner images of the respective colors of yellow (Y), magenta (M), cyan (C) and black (K) which are successively formed on the surfaces of the image carriers34are transferred and superposed onto the intermediate transfer belt32arranged aslope above the image forming units30Y,30M,30C,30K of the respective colors by the primary transfer members46.

As shown inFIG. 3, under certain tension the intermediate transfer belt32is wound on a driving roll48for applying driving force to the intermediate transfer belt32, a rotationally driven support roll50, a tension applying roller54for applying tension to the intermediate transfer belt32, a first idler roll56and a second idler roll58.

As shown inFIG. 15, the lower surface of the intermediate transfer belt32is tilted with respect to the horizontal direction H by only an angle of θ as in the case of the tilt angle of the image forming units30(seeFIG. 3) arranged aslope side by side.

A cleaning device52for cleaning the surface of the intermediate transfer belt32is provided at the opposite side to the driving roll48so that the intermediate transfer belt32is sandwiched between the cleaning device52and the driving roll48, and the cleaning device52is freely attachable to and detachable from the apparatus main body10A by opening a front cover156provided at the front side of the apparatus main body10A (the front side at which a user stands) (seeFIG. 6).

A secondary transfer member60for secondarily transferring a toner image primarily-transferred on the intermediate transfer belt32to a recording sheet P as a recording medium is disposed at the opposite side to the support roll50so that the intermediate transfer belt32is sandwiched between the secondary transfer belt60and the support roll50. That is, the gap between the secondary transfer member60and the support roll50serves as a secondary transfer position at which a toner image is transferred onto a recording sheet P.

As shown inFIG. 4, a fixing device64for fixing a toner image onto a recoding sheet P is provided at the upper side of the secondary transfer member60. That is, a toner image is transferred onto a recording sheet P by the secondary transfer60, and then the recording sheet P is transported along a transporting path62to the fixing device64to fix the toner image on the recording sheet P.

A transporting roll66for transporting the recording sheet P having the toner image fixed thereon is provided at the downstream side in the transporting direction of the recording sheet P with respect to the fixing device64(hereinafter referred to as “at the downstream side in the transporting direction”), and a switching gate68for switching the transporting direction of the recording sheet P is provided at the downstream side in the transporting direction of the transporting roll66.

A first discharge roll70is provided at the downstream side in the transporting direction of the switching gate68, and a recording sheet P guided by the switching gate68which is switched to one side is discharged to a first discharge portion69by the first discharge roll70.

A second discharge roll74and a third discharge roll78are further provided at the downstream side in the transporting direction of the switching gate68. A recording sheet P which is guided by the switching gate68switched to the other side and then transported by a transporting roll73is discharged to a second discharge portion72by the second discharge roll, or discharged to a third discharge portion76by the third discharge roll78.

Supply sheet trays80,82,84and86in which recording sheets P are stacked are provided at the lower portion of the apparatus main body10A and also at the upstream side in the transporting direction of the recording sheet P with respect to the secondary transfer member60(hereinafter referred to as “the upstream side in the transporting direction”). Recording sheets P different in size are stacked in the respective supply sheet trays80,82,84and86.

A sheet feed roll88is provided to each of the sheet feeders80,82,84and86to feed recording sheets P from the corresponding supply sheet tray (80,82,84,86) into the transporting path62, and transporting rolls90and92for successively transporting the recording sheets P one by one are provided at the downstream side in the transporting direction of each sheet feed roll88.

Furthermore, a registration roll94for temporarily stopping each recording sheet P and feeding out it to the secondary transfer position at a predetermining timing is disposed at the downstream side in the transporting direction of the transporting roll92.

Furthermore, in order to form images on both the sides of a recording sheet P, a reversible transporting unit98for reversing and transporting a recording sheet P is provided at the side of the secondary transfer position. The reversible transporting unit98is provided with a reversing path100in which a recording sheet P being transported by reversely rotating the transporting roll73. Plural transporting rolls102are provided along the reversing path100, and the recording sheet P is transported into the positioning roll94again by these transporting rolls102while both the sides thereof are reversed.

A foldable manual sheet feeder106is provided beside the reversible transporting unit98, and a sheet feed roll108and transporting rolls110and112are provided to transport a recording sheet P fed from the opened foldable manual sheet feeder106. A recording sheet P transported by the transporting rolls110and112is transported to the registration roll94.

Next, the intermediate transfer unit120containing the intermediate transfer belt32as an constituent part will be described.

As shown inFIG. 3, the intermediate transfer unit120is configured to include the intermediate transfer belt32, and the driving roll48, the support roll50, the tension applying roll54, the first idler roll56, the second idler roll58on which the intermediate transfer belt32is wound. The intermediate transfer unit120is attachable to and detachable from one side surface (the side surface of the left side shown inFIG. 3) of the apparatus main body10A by opening a cover (not shown).

As shown inFIGS. 14A and 14B, the intermediate transfer unit120is provided with a retract handle122. By rotating the retract handle122, the first and second idler rolls56and58and the primary transfer members46Y,46M,46C and46K are upwardly retracted, and the intermediate transfer belt32is separated from the image carriers34of the image forming units30Y,30M,30C and30K of the respective colors.

Specifically, as shown inFIG. 14B, the retract handle122is secured to the intermediate transfer unit120so as to be freely turnable. Furthermore, a holding frame124on which the first idler roll56, the second idler roll58and the primary transfer members46Y,46M,46C and46K are freely rotatably mounted is joined to the retract handle122through a link mechanism (not shown).

By turning the retract handle122, the holding frame124is moved in a direction (the direction of an arrow inFIG. 14B) intersecting to the circulating direction of the intermediate transfer belt32, and the intermediate transfer belt32is separated from the image carriers34of the respective colors by elastic force.

Furthermore, a guide rail member130is provided in the apparatus main body10A (seeFIG. 3) as shown inFIGS. 11 and 12. The guide rail member130guides the intermediate transfer unit120which is attachable to/detachable from one side surface of the apparatus main body10A, and supports the intermediate transfer unit120mounted in the apparatus main body10A.

The guide rail member130has a guide rail member130A mounted at the inside of a front frame member132(at the side where the intermediate transfer unit120is disposed) which is provided at the front side (at the front side where a user stands) and designed as a plate-shaped structural member, and a guide rail member130B mounted at the inside of a rear frame member134which is provided at the rear side (at the back side where the user does not stand) and designed as a plate-shaped structural member.

Guide grooves144along which the intermediate transfer unit120is guided are formed in the guide rail members130A and130B, and the shapes of the guide grooves144are determined so as to change the guide direction of the intermediate transfer unit120halfway.

Specifically, as shown inFIGS. 13A and 13B, the guide grooves144formed in the guide rail members130A and130B guide two guide pins140and142provided to the intermediate transfer unit120.

Each of the guide grooves144has a first site144A that is sloped so that the end portion of the attaching/detaching side (the left side of the paper surface ofFIGS. 13A and 13B) is slightly higher, a second site144B that is sloped so that the end portion of the back side (the right side of the paper surface ofFIGS. 13A and 13B) is located at a predetermined height with respect to the horizontal direction, and a bent portion144C at which the first site144A and the second site144B are joined to each other.

In the above construction, when the intermediate transfer unit120is mounted in the apparatus main body10A, the retract handle122is first rotated to retract the first idler roll56, the second idler roll58and the primary transfer members46Y,46M,46C and46K from the image carriers34as shown inFIGS. 6,13and14.

Furthermore, the two guide pins140and142of the intermediate transfer unit120are inserted into the guide grooves144of the guide rail members130A and130B in a state that a side surface cover150provided to the side surface of the apparatus main body10A is open. Thereafter, the intermediate transfer unit120is pushed into the apparatus main body10A as shown inFIG. 5. Accordingly, the two guide pins140and142of the intermediate transfer unit120are guided along the guide grooves144of the guide rail members130A and130B as shown inFIGS. 13A and 13B. A chevron-shaped projection144D is formed at the attaching/detaching side of each guide groove144(entrance side), whereby the guide pins140and142of the intermediate transfer unit120are prevented from dropping off from the guide grooves144.

Furthermore, in a state that the mounting of the intermediate transfer unit120in the apparatus main body10A is completed, a positioning pin152provided to the intermediate transfer unit120is fitted into positioning grooves154formed in the guide rail members130A and130B, thereby stabilizing the attitude of the intermediate transfer unit120when the mounting is completed.

The retract handle122is rotated to make the primary transfer members46Y,46M,46C and46K abut against the confronting image carriers34through the intermediate transfer belt32, whereby the mounting work of the intermediate transfer unit120is completed. When the intermediate transfer unit120is detached from the apparatus main body10A, the work may be executed in the reverse process to the mounting work.

Furthermore, the intermediate transfer unit120is provided with plural power supply units158Y,158M,158C and158K at the guide rail member130B side as shown inFIG. 11. Under the state that the intermediate transfer unit120is mounted in the apparatus main body10A, the plural power supply units158Y,158M,158C and158K are brought into electrical contact with power supply units160Y,160M,160C and160K provided to the guide rail member130B, whereby power can be supplied. Accordingly, power is supplied from the power supply units160Y,160M,160C and160K to the primary transfer members46Y,46M,46C and46K provided to the intermediate transfer unit120by the plural power supply units158Y,158M,158C and158K.

(Configuration of Main Parts)

As shown inFIG. 10, a recessed air flow path170opened at the rear frame member134(seeFIG. 11) side is provided to the guide rail member130of the rear side (the back side at which the user does not stand) so as to extend along the moving direction of the intermediate transfer belt32(seeFIG. 1). Furthermore, a cover member172that covers the recessed air flow path170from the rear frame member134(seeFIG. 11) side so as to prevent air flowing in the air flow path170from leaking to the outside is provided to the guide rail member130B. That is, as shown inFIG. 7, the flow path170is covered by the cover member172, and disposed at the intermediate transfer belt32(seeFIG. 11) side of the rear frame member134.

In this example, the air flow path170is provided to the guide rail member130B. However, the air flow path170may be a member separate from the guide rail member130B insofar as the member serves as a passage through which air flows along the moving direction of the intermediate transfer belt32.

As shown inFIGS. 9 and 10, one end portion of the flow path170is not covered by the cover member172and thus it is opened, and a guide member174is joined to the opened portion of the flow path170at one end portion thereof, and leads air flowing through the flow path170to the rear side of the apparatus main body10A (the back side at which the user does not stand).

Specifically, the guide member174is provided at the rear side of the rear frame member134as shown inFIG. 11, and the air flowing through the flow path170flows into the guide member174through an opening184formed in the rear frame member134as shown inFIG. 8.

Furthermore, a filter member176for catching particles in air flowing through the flow path170is freely detachably mounted in the guide member174as shown inFIGS. 9 and 10. A fan178for sucking air from the flow path170and exhausting the sucked air through a vent180to the outside of the apparatus main body10A is provided at the other end portion of the guide member174. The vent180is disposed beside the fan178.

As shown inFIG. 11, the fan178is provided at the one end portion of the flow path170, thereby preventing interference between a gear member190for transmitting driving force to the image forming unit30of each color and the fan178.

On the other hand, as shown inFIG. 1, a suction port182is formed in the wall surface (at the intermediate transfer belt32side) of the guide rail member130B constituting the flow path170. Floating fine toner particles (hereinafter referred to as “toner cloud”) floating in the space surrounded by the image carrier34, the developing unit42and the intermediate transfer belt32is sucked through the suction port182into the flow path170. That is, the suction port182is provided at an air suction position of the space surrounded by the image carrier34, the developing unit42and the intermediate transfer belt32.

Specifically, the guide rail member130B is provided with a suction port182Y for sucking toner cloud floating in the space surrounded by the image carrier34Y, the developing unit42Y and the intermediate transfer belt32, a suction port182M for sucking toner cloud floating in the space surrounded by the image carrier34M, the developing unit42M and the intermediate transfer belt32, a suction port182C for sucking toner cloud floating in the space surrounded by the image carrier34C, the developing unit42C and the intermediate transfer belt32, and a suction port182K for sucking toner cloud floating in the space surrounded by the image carrier34K, the developing unit42K and the intermediate transfer belt32.

The size of each of the suction ports182Y,182M,182C and182K is determined in accordance with the distance from the fan178. That is, the opening area of the suction port182Y located at the most remote position from the fan178is set to be largest, and the opening area of the suction port is successively reduced as the suction port approaches the fan178.

That is, the suction power of the fan178at the suction port182Y is weakest because the suction port182Y is farthest away from the fan178, and thus the opening area of the suction port182Y is set to the largest value. Rather, the suction power of the fan178at the suction port182K is strongest because the suction port182K is nearest to the fan178, and thus the opening area of the suction port182K is set to the smallest value.

As is apparent from the positional relationship of the guide rail member130B, the intermediate transfer belt32, the image carriers of the respective colors and the developing units42of the respective colors inFIG. 1, the driving roll48, etc. of the intermediate transfer unit120are omitted from the illustration ofFIG. 1.

As shown inFIG. 3, the charging member36provided to the image forming unit30of each color uniformly charges the surface of the corresponding image carrier34.

Furthermore, the image data of the respective colors are successively output to the exposure devices40that are individually provided to the image forming units30of the respective colors. The surface of each image carrier34is exposed to and scanned with light emitted from the corresponding exposure device40in accordance with the image data, and an electrostatic latent image is formed on the surface of the image carrier34by the primary transfer members46.

The electrostatic latent images formed on the surfaces of the image carriers34are successively developed into toner images of respective colors of yellow (Y), magenta (M), cyan (C) and black (K) by the developing units42of the respective colors. The toner images of the respective colors of yellow (Y), magenta (M), cyan (c) and black (K) that are successively formed on the respective surfaces of the image carriers34of the respective colors are transferred and superposed onto the intermediate transfer belt32.

When an electrostatic latent image formed on the surface of the image carrier34is developed into a toner image by the developing unit42, and also when a toner image formed on the surface of the image carrier34is transferred onto the intermediate transfer belt32, extra toner occurs as toner cloud in the space surrounded by the image carrier34, the developing unit42and the intermediate transfer belt32.

As shown inFIGS. 7,9and10, the fan178sucks air flowing through the flow path170and exhausts the air from the vent180(seeFIG. 11). As shown inFIG. 1, the fan178sucks the air in the flow path170, whereby suction force for sucking air in the space surrounded by the image carrier34, the developing unit42and the intermediate transfer belt32occurs in the suction ports182Y,182M,182C and182K formed in the wall surface of the flow path170.

The toner cloud floating in the space surrounded by the image carrier34of each color, the developing unit42of each color and the intermediate transfer belt32is sucked from each of the suction ports182Y,182M,182C and182K into the flow path170and captured by the filter member176, and then air containing no toner is exhausted from the vent180to the outside by the suction force occurring in the suction ports182Y,182M,182C, and182K.

As described above, the toner cloud occurring in the plural image forming units30arranged along the intermediate transfer belt32is discharged from the flow path170formed along the intermediate transfer belt32.

That is, the suction port182is formed at an air suction position in the space surrounded by the image carrier34, the developing unit42and the intermediate transfer belt32. Therefore, the toner cloud floating in the space surrounded by the image carrier34of each color, the developing unit42of each color and the intermediate transfer belt32is sucked from each suction port182into the flow path170by the suction force occurring in the suction port182, passed through the flow path170and then discharged to the outside of the flow path170.

Furthermore, the opening area of the suction port182Y at which the suction force of the fan178is weakest is set to the largest value, and the opening area of the suction port182K at which the suction force of the fan178is strongest is set to the smallest value, whereby the toner clouds occurring in the image forming units30of the respective colors are sucked from the respective suction ports182all over (the suction amounts of air from the respective suction ports182can be approached to a fixed value).

Increase in size of the rear side of the apparatus main body10A is suppressed by providing the flow path170at the intermediate transfer belt32side of the rear frame member134.

The number of parts is reduced by providing the flow path170to the guide rail member130B.

As compared with a case where an air intake duct is provided over the whole width of the developing unit, toner cloud occurring in the image forming unit30can be discharged to the outside of the flow path170by utilizing a smaller space.

Furthermore, by providing the fan178at one end portion of the flow path170, the fan178is disposed without interfering with the gear member190.

The present invention is not limited to the above exemplary embodiment, and various modifications may be made without departing from the subject matter of the present invention. For example, in the above exemplary embodiment, the toner cloud occurring in the image forming unit30of each color is sucked from each suction port182all over, however, the toner cloud may be sucked from each suction port all over by changing the cross-sectional area of the flow path170to adjust the suction force of each suction port182.

The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments were chose and described in order to best explain the skilled in the air to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.