Image forming apparatus including a plurality of image forming sections and a plurality of discharging pipes

An image forming apparatus includes: a plurality of image forming sections respectively including developing portions and first removing portions as defined herein; a plurality discharging pipes as defined herein; and a delivery pipe as defined herein, the delivery pipe includes a changing portion in which a direction of delivering the coloring materials is changed to an upper side, and, among the discharging pipes, a discharging pipe that is downward extended from one of the first removing portions that is placed on a most downstream side in the oblique direction is disposed downstream from the changing portion of the delivery pipe in the delivering direction, and has a length shorter than lengths of the other discharging pipes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-068297 filed on Mar. 19, 2009.

BACKGROUND

Technical Field

The present invention relates an image forming apparatus.

SUMMARY

According to an aspect of the invention, there is provided an image forming apparatus including: a plurality of image forming sections respectively having: developing portions which develop latent images formed on image carriers by using different coloring materials; and first removing portions which, after the images developed by the developing portions are transferred to transfer member, remove the coloring materials remaining on the image carriers, the image forming sections being arranged in a direction oblique to installation surface of a main unit of the apparatus; a plurality of discharging pipes which are placed below the plurality of image forming sections, which deliver the coloring materials removed by the first removing portions of the plurality of image forming sections, and which are downward extended from the first removing portions, respectively; and a delivery pipe which delivers the coloring materials introduced through the discharging pipes, to a recovery container, wherein the delivery pipe includes a changing portion in which a direction of delivering the coloring materials is changed to an upper side, and, among the discharging pipes, a discharging pipe which is downward extended from one of the first removing portions that is placed on a most downstream side in the oblique direction is disposed downstream from the changing portion of the delivery pipe in the delivering direction, and a length of the discharging pipe is shorter than lengths of the other discharging pipes.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

DETAILED DESCRIPTION

First Exemplary Embodiment

FIG. 1is a diagram showing a configuration example of an image forming apparatus of a first exemplary embodiment of the invention. For example, the image forming apparatus1is a digital color printer, and has a controlling section (not shown) which applies image processing to image data transmitted from a host apparatus such as a personal computer. The image forming apparatus1is configured so that the data are converted to color image data of yellow (Y), magenta (M), cyan (C), and black (K), and then a toner image based the color image data is formed on a sheet P.

The image forming apparatus1may be a copier, a facsimile apparatus, or a multi-function apparatus having a plurality of functions of a copier, a printer, a scanner, a facsimile apparatus, and the like. The image forming apparatus1may be connected to the host apparatus through a network such as a local area network (LAN), or in accordance with an interface standard such as USB or RS232C.

The image forming apparatus1has a case11as the apparatus main unit having a substantially box-like shape. A sheet feeding device12which houses sheets P is detachably disposed in a lower portion the case11. In an upper portion of the case11, a sheet discharging portion13onto which a recorded sheet P is to be discharged is disposed, and a sheet conveying path14as a recording member conveying path is formed so as to be extended from the sheet feeding device12to the sheet discharging portion13. An installation surface11awhich is used in the case where the case11is installed on a floor or a table is disposed in the lower side of the case11.

A pickup roll14awhich takes in the sheets P one by one from the sheet feeding device12to the sheet conveying path14, a retard roll14bwhich, in order to prevent the taken out sheet from double feeding, applies a force in a direction that is opposite to the conveying direction, on the rear face of the sheet, a correcting roll14cwhich corrects the skew of the sheet P, and a fixing device15which fixes a toner image to the sheet P by means of heat and pressure are arranged on the sheet conveying path14.

In the image forming apparatus1, an image formation processing section20which forms toner images by using a plurality of color toners as different coloring materials is disposed in a middle portion case11, and a toner recovering device50which recovers waste toner discharged from image formation processing section20is disposed below the image formation processing section20. The waste toner which is to be recovered by the toner recovering device50may include magnetic carriers, paper dusts of the sheet P, powder dusts in the case11, and the like, in addition to the toners.

The image formation processing section20includes: an intermediate transfer belt33which can be circularly moved in the direction of the arrow in the figure, which functions as a transfer member; image forming units21Y,21M,21C,21K that are detachably arranged outside the intermediate transfer belt33while forming a constant gap and in direction oblique to the installation surface11a, that respectively have photosensitive members22on which color toner images of YMCK are respectively formed while being rotated in the direction of the arrows in the figure, and which action as image carrier members, and that function as image forming sections; and primary transfer rolls26Y,26K,26C,26K which are placed inside the intermediate transfer33, and which primary-transfer the toner images formed on the surfaces of the photosensitive members22to the intermediate transfer belt33, respectively.

The intermediate transfer belt33is stretched by a plurality of rotary members. Specifically, the intermediate transfer belt33is stretched by: a driving roll30which drives the intermediate transfer belt33to be circularly moved, by a driving source (not shown) such as a motor; a backup roll31which is placed at a position where toner images are transferred to the sheet P, and which supports the intermediate transfer belt33; and a driven roll32which is placed downstream from the image formation processing section20in the circularly moving direction of the intermediate transfer belt33, and which is rotated in accordance with the circular movement of the intermediate transfer belt33.

The image forming units21Y,21M,21C,21K are configured in the same manner. Each of the image forming units21Y,21M,21C,21K includes: the photosensitive member22; a charging device23which uniformly charges the surface of the photosensitive member22; a developing device24which develops an electrostatic latent image formed on the surface of the photosensitive member22by an exposing device27, by a toner to form a toner image on the surface of the photosensitive member22; and a photosensitive member cleaning portion25which recovers waste toner remaining on the surface of the photosensitive member22, and which functions as a first removing portion.

The developing device24has a housing24awhich houses a toner. In the housing24a, a developing roll24bwhich supplies the toner to the photosensitive member22to develop an electrostatic latent image on the photosensitive member22with the toner; a supply auger24cwhich supplies the toner to the developing roil24b; and a stir auger24dwhich stirs and supplies the toner to the supply auger24care disposed. The color toners are supplied from toner cartridges35Y,35M,35C,35K to the respective developing devices24.

The photosensitive member cleaning portion25has a housing25awhich houses the waste toner recovered from the photosensitive member22, and, in the housing25a, includes: a blade25bwhich is contacted with the surface of the photosensitive member22to scrape off waste toner; and a discharge auger25cwhich is rotatably disposed in the housing25a, and which is rotated to convey the waste toner that is scraped off by the blade25bto be accumulated the housing25a, toward the rear side of the image forming apparatus1. A discharge port25dthrough which the waste toner conveyed by the discharge auger25cis discharged to the toner recovering device50is formed in a lower end portion of the rear side of the housing25a.

The exposing device27includes components which are not shown, or four semiconductor laser devices which emit laser beams modulated with the color image data of YMCK, a polygon mirror which diverges the laser beams emitted from the semiconductor laser devices, and a plurality of mirrors which reflect the laser beams diverged by the polygon mirror, to irradiate the photosensitive members22with the laser beams, thereby forming electrostatic latent images on the surfaces of the photosensitive members22. The exposing device27is hermetically closed by frames so as not to be contaminated with the toners and the like.

In the periphery of the intermediate transfer belt33, a secondary transfer roil34which is placed on the side opposite to the backup roll31across the intermediate transfer belt33, and which secondary transfers the toner images on the intermediate transfer belt33to the sheet P, and a belt cleaning portion40which is placed on the side opposite to the driving roll30across the intermediate transfer belt33, which presses the intermediate transfer belt33toward the driving roll30to scrape off and recover waste toner remaining on the surface of the belt, and which functions as a second removing portion.

The belt cleaning portion40has a housing40awhich houses the waste toner recovered from the intermediate transfer belt33, and, in the housing40a, includes: a blade40bwhich is contacted with the surface of the intermediate transfer belt33to scrape off waste toner; and a discharge auger40cwhich is rotatably disposed in the housing40a, and which is rotated to convey the waste toner that is scraped off by the blade40bto be accumulated in the housing25a, toward the rear side of the image forming apparatus1. A discharge port40dthrough which the waste toner conveyed by the discharge auger40cis discharged to the toner recovering device50is formed in a lower end portion of the rear side of the housing40a.

The toner recovering device50includes: a recovery container51which houses the waste toner; a conveying pipe52which conveys the waste toner removed by the photosensitive member cleaning portion25and the belt cleaning portion40, to the recovery container51; a conveyor auger53which is rotatably disposed in the conveying pipe52, which is rotated to convey the waste toner to the recovery container51, and which functions as a conveying member; and a motor54which rotates the conveyor auger53, and which functions as a driving source.

The conveying pipe52is placed in the rear side of the image forming apparatus1, so as not to interfere with the imago forming units21Y,21M,21C,21K, a driving source and gear train which are not shown, and which drive the photosensitive members22of the image forming units21Y,21M,21C,21K, and the like, and connected to the discharge ports25dof the photosensitive member cleaning portions25, and also to the discharge port40dof the belt cleaning portion40.

(Detailed Configuration of the Toner Recovering Device)

FIG. 2is a sectional view showing a configuration example of the toner recovering device,FIG. 3is a plan view showing a configuration example of the conveyor auger, andFIG. 4is a perspective view showing configuration examples of the conveying pipe and the recovery container.

The recovery container51is placed in a so-called dead space which is interposed among the sheet conveying path14, the image forming unit21K, and the exposing device27, and inserted from the front side of the case11to the rear side, i.e., in the direction of arrow A shown inFIG. 4, whereby the recovery container is attached to the case11. The very container51has: an introducing port51ato which, when the container is attached to the case11, the waster is introduced from the conveying pipe52; a step portion51bwhich is recessed so as not to interfere with the conveying pipe52; and a housing portion51cin which the level from the installation surface11apartly overlaps with that of the conveying pipe52. The step portion51band the housing portion51care hollows and communicate with each other, so that the waste toner introduced through the introducing port51ais housed in the portions. A shutter which prevents the waste toner from leaking when the container is detached from the case11may be disposed in the introducing port51a.

As shown inFIG. 2, the conveying pipe52is configured by: a belt waste toner discharging pipe520which is downward extended from the belt cleaning portion40; four photosensitive member waste toner discharging pipes521Y,521M,521C,521K which are downward extended from the photosensitive member cleaning portions25of the image forming units21Y,21M,21C,21K, respectively; and a delivery pipe522having a delivery port522dthrough which the waste toner introduced through the belt waste toner discharging pipe520and the photosensitive member waste toner discharging pipes521Y,521M,5210,521K is delivered to the recovery container51.

The conveying pipe52is formed by a resin such as an ABS resin, a polyacetal resin, or a polystyrene resin, or a metal such as aluminum. For example, the conveying pipe52is produced in the following manner. One set of members having a shape which is divided by the section shown inFIG. 2is produced by a resin molding process, and the members are assembled while being opposed to each other. The radial sectional shape of the conveying pipe52may be circular or polygonal, but is not restricted thereto.

The belt waste toner discharging pipe520has in the upper part a receiving port520awhich is connected to the discharge port40dof the belt cleaning portion40. Inside the belt waste toner discharging pipe520, a spring520bwhich is placed below the belt cleaning portion40, and a movable member520cwhich is fixed to a lower portion of the spring520b, and which is vertical movable in conjunction with the rotation of the conveyor auger53are disposed.

The photosensitive member waste toner discharging pipes521Y,5211,5210,521K have in an upper portion receiving ports521awhich are connected to the discharge ports25dof the photosensitive member cleaning portions25of the image forming units21Y,21M,21C,21K, respectively. Shutters521bwhich open and close the receiving ports521aare disposed. Each of the shutters521bis configured so that, when a corresponding one of the image forming units21Y,21M,21C,21K is attached, the shutter is opened.

The delivery pipe522is connected to the belt waste toner discharging pipe520and the photosensitive member waste toner discharging pipes521Y,521M,521C,521K, and also to the recovery container51through the delivery port522d.

The delivery pipe522is placed while changing the direction of delivering the waste toner to the upper side so that, among the four connected photosensitive member waste toner discharging pipes521Y,521M,521C,521K, the length L4of the photosensitive member waste toner discharging pipe521K which is downward extended from the image forming unit21K that is placed on the most downstream side in the oblique direction is shorter than the lengths L1to L3of the other the photosensitive member waste toner discharging pipes521Y,521M,521C.

Along the direction from the upstream side in the delivering direction to the downstream side, the delivery pipe522has an upstream portion522a, a curved portion522bwhich functions as a changing portion, and a downstream portion522c. In the upstream portion522a, the belt waste toner discharging pipe520and the three photosensitive member waste toner discharging pipes521Y,521M,521C which are on the upstream side are connected to the conveying pipe, and the direction of delivering the waste ton set to an oblique downward direction. The curved portion522bis placed in a state where the portion is curved so that the delivering direction is changed from the oblique downward direction to the upper side, i.e., an oblique upward direction. In the downstream portion522c, the photosensitive member waste toner discharging pipe521K is connected to the conveying pipe, and the direction of delivering the waste is set to an oblique upward direction.

A configuration may be contemplated where the delivering direction of the upstream portion522aof the conveying pipe is set to an oblique downward direction, the curved portion522bis not disposed, and the downstream portion522cis extended while maintaining the same inclination as the upstream portion522a, and connected to the recovery container51. In such a case, in order to ace the recovery container51, however, the dimension of the apparatus main body in the height direction must be increased, and the size of the apparatus becomes large. According to the exemplary embodiment, by contrast, the direction delivering the waste is set to the oblique upward direction by the curved portion, whereby the size of the apparatus is reduced. Since the discharging pipe521which is connected to the downstream side from the curved portion522bis shorter than the other discharging pipes, the recovery efficiency in the discharging pipe521is excellent.

In the market, the rate of the monochrome printing is higher than that of the full-color printing. In the image forming unit21K which is connected to the downstream portion522cthrough the photosensitive member waste toner discharging pipe521K, and which uses the black toner, therefore, the amount of waste toner is larger as compared with the image forming units21Y,21M,21C using the toners of the other colors. In the configuration where the direction of the delivery pipe522is changed to the oblique upward direction, consequently, the length L4of the photosensitive member waste toner discharging pipe521K is shortened, and the recovery efficiency of the waste toner is improved.

Although the exemplary embodiment is configured so that the angle by which the image forming unit21K is obliquely placed substantially coincides with that of the delivering direction the delivery pipe522, the angles may be different from each other. For example, the angle of the delivering direction of the delivery pipe522may approach one of the horizontal and vertical directions, or the angle of the placement of the image forming unit21K may approach one of the horizontal and vertical directions.

As shown inFIGS. 2 and 3, the conveyor auger53includes a rotation shaft530fixed to the motor54, and a conveying vane531and circulating vane532which are spirally formed in the periphery of the rotation shaft530.

The conveyor auger53is made of a bendable material, and integrally formed by a molding process using a resin such as an ABS resin, a polycarbonate resin, a polyacetal resin, or a polystyrene resin, or a metal such as aluminum. The conveying vane531and the circulating vane532may not be spirally formed on the rotation shaft530. Alternatively, a plurality of feeding plates may be inclinedly disposed on the rotation shaft530. In the exemplary embodiment, as shown inFIG. 3, the conveyor auger53is linearly formed, then curved so as to coincide with the shape of the delivery pipe522, and thereafter placed in the delivery pipe522. Alternatively, the conveyor auger may be previously curved so as to coincide with the shape of the delivery pipe522.

The rotation shaft530is configured so that the diameter of a shaft portion is changed depending on the zone of the delivery pipe522where the shaft portion is placed, and has: a standard diameter portion530ahaving a standard diameter of the rotation shaft530; a small diameter portion530bwhich is smaller in diameter than the standard diameter portion530a; a large diameter portion530cwhich is larger in diameter than the standard diameter portion530a; a very large diameter portion530dwhich is larger in diameter than the large diameter portion530c; and a taper portion530ein which the diameter is gradually reduced.

The small diameter portion530bis disposed in the curved portion522bso that the rotation shaft easily follows the shape of the curved portion522b.

The large diameter portion530cis disposed at a position where the recovery container51is connected to the delivery pipe, or a position where the conveying vane531and the circulating vane532are omitted, so that strength of the rotation shaft530is enhanced.

The very large diameter portion530dis disposed at a position where the movable member520cof the belt waste toner discharging pipe520is placed, so that the height of the conveying vane531is reduced in order to cause the movable member520cto easily override the conveying vane531.

The taper portion530eis disposed downstream from the very large diameter portion530d. The diameter of the taper portion is gradually reduced, and finally coincides with that of the standard diameter portion530a. The taper portion530ehas a function of gradually increasing the conveying speed of the waste tone, and adjusting the conveying amount of the waste toner per unit time.

The conveying vane531is formed in the periphery of the rotation shaft530on the upstream side from the large diameter portion530c. When the rotation shaft530is rotated by the rotation or the motor54, the conveying vane531conveys the waste toner discharged from the belt waste toner discharging pipe520and the photosensitive member waste toner discharging pipes521Y,521M,521C,521K, along the rotation shaft530to the delivery port522d, and delivers the waste toner the recovery container51through the delivery port522d.

The circulating vane532is formed in the periphery of the rotation shaft530on the downstream side from the large diameter portion530c, in a direction opposite to the conveying vane531. The circulating vane532conveys the waste toner conveyed by the conveying vane531, so as to push back the waste toner in a direction opposite to the delivering direction.

(Operation of Image Forming Apparatus)

Next, an example of the operation of the image forming apparatus will be described. Hereinafter, the case where the user operates the host apparatus to transmit to-be-processed image data to the image forming apparatus1will be described.

When the image forming apparatus1receives the image data from the host apparatus, the apparatus controls the image formation processing section20and the like to form images based on the image data.

The image formation processing section20causes the photosensitive members22of the image forming units21Y,21M,21C,21K to be rotated, charges the photosensitive members22by the charging devices23, and then irradiates the photosensitive members22with the laser beams for the respective colors which are based on the image data and emitted from the exposing device27, thereby forming electrostatic latent images on the surfaces of the photosensitive members22. Next, the electrostatic latent images on the photosensitive members22are developed by the developing devices24for the corresponding colors to charged toner images, and then gradually primary transferred onto the intermediate transfer belt33driven by the driving roll30, by the primary transfer rolls26Y,26M,26C,26K.

After the toner images are primary transferred, toners remaining on the surfaces of the photosensitive members22are scraped off by the blades25bof the photosensitive member cleaning portion25, and then housed in the housings25a. The waste toners housed in the housings25aare conveyed towards the rear side by the rotations of the discharge augers25c, to be discharged into the photosensitive member waste toner discharging pipes521Y,521M,521C,521K through the discharge ports25d.

On the other hand, in parallel with the operation of the image formation processing section20, the sheet P is conveyed one by one from the sheet feeding device12by the pickup roll14aand the retard14b, and the skew is corrected by the correcting roll14c. When the sheet P is conveyed to the position where the secondary transfer roll34is placed, in synchronization with the circular movement of the intermediate transfer belt33, the toner images on the intermediate transfer belt33are secondary transferred to the sheet P by the secondary transfer roll34. The sheet P onto which the toner images are secondary transferred is heated and pressurized by the fixing device15, thereby fixing the toner images, and then discharged to the sheet discharging portion13.

After the toner images are secondary transferred from the intermediate transfer belt33to the sheet P, a toner remaining on the surface of the intermediate transfer belt33is scraped off by the blade40bof the belt cleaning portion40, and then housed into the housing40a. The waste toner housed in the hour housing40ais conveyed toward the rear side by the rotation of the discharge auger40c, and discharged to the belt waste toner discharging pipe520through the discharge port40d.

In the image formation, the waste toner removed by the belt cleaning portion40is conveyed to the belt waste toner discharging pipe520through the receiving port520a. When the conveyor auger53is rotated by the motor54, the movable member520cin the conveying pipe52is vertically moved by successive overriding of the member over the conveying vane531of the conveyor auger53. As a result, also the spring520bfixed to the movable member520cis vertically moved. While preventing the toner from adhering to the inner wall face of the belt waste toner discharging pipe520, therefore, the waste toner removed by the belt cleaning portion40drops from the belt waste toner discharging pipe520into the upstream portion522a.

The waste toner which drops into the upstream portion522ais conveyed in the oblique downward direction along the rotation shaft530by the conveying vane531.

In the upstream portion522a, the waste toners removed, by the photosensitive member cleaning portions25of the image forming units21Y,21M,21C are introduced through the connected photosensitive member waste toner discharging pipes521Y,521M,521C, and then conveyed in the oblique direction by the conveying vane531.

When the waste toner which is conveyed in the oblique direction reaches the curved portion522b, the waste toner arcuately advances along the curved rotation shaft530through the curved portion522b, so that the conveying direction of the waste toner is changed to the upper side, and then the waste toner reaches the downstream portion522c.

In the downstream portion522c, then, the waste toner removed by the photosensitive member cleaning portion25of the image forming unit21K is introduced through the photosensitive member waste toner discharging pipe521K, and conveyed in the oblique upward direction by the conveying vane531.

When the waste toner which is conveyed in the oblique upward direction reaches the delivery port522din the downstream portion522c, the waste toner is recovered into the recovery container51through the delivery port522d. At this time, the waste toner which has passed over the delivery port522dis pushed back in the opposite direction by the circulating vane532, whereby the waste toner is recovered into the recovery container51through the delivery port522d.

Second Exemplary Embodiment

FIG. 5is a diagram showing a configuration example of an image forming apparatus of a second exemplary embodiment of the invention. In the image forming apparatus1of the first exemplary embodiment, the upstream portion522aof the delivery pipe522is placed so as to convey the waste toner in the oblique downward direction. In the image forming apparatus1of the present exemplary embodiment, by contrast, the upstream portion522aof the delivery pipe522is placed so as to horizontally deliver the waste toner.

In the upstream portion522a, the direction of delivering the waste toner is set to the horizontal direction, and, in the downstream portion522c, the direction is set to an obliquely upward direction. The curved portion522bbetween the upstream portion522aand the downstream portion522cis curvedly placed so that the delivering direction is changed from the horizontal direction to the obliquely upward direction. The other basic configuration and operation of the image forming apparatus1are identical with those of the first exemplary embodiment, and hence their detailed description is omitted.

Other Exemplary Embodiments

The invention is not restricted to the exemplary embodiments, and may be variously implemented without departing from the spirit of the invention. In the image forming apparatuses1of the exemplary embodiments, for example, toner images on the photosensitive members22are transferred, through the intermediate transfer belt33which functions as a transfer member, to the sheet P which functions as another transfer member. Alternatively, the intermediate transfer belt33may be omitted, and toner images on the photosensitive members22may be directly transferred to the sheet P.

In the exemplary embodiments, the curved portion522bof the delivery pipe522is placed so as to be bent at a predetermined radius of curvature. Alternatively, the curved portion may be placed while being bent so that the upstream portion522aand the downstream portion522cintersect with each other at a predetermined angle.

In the exemplary embodiments, the curved portion522bof the delivery pipe522is disposed in one place. Alternatively, the curved portion may be placed at plural places.