Patent ID: 12228874

In the following description, a right-hand side and a left-hand side inFIG.2to a viewer will be defined as a front side and a rear side, respectively, of an image forming apparatus1, and a nearer side and a farther side to the viewer with respect to a cross section inFIG.2will be defined as a leftward side and a rightward side, respectively, of the image forming apparatus1. An upper side and a lower side inFIG.2will be defined as an upper side and a lower side, respectively, of the image forming apparatus1. A front-to-rear or rear-to-front direction may be called as a front-rear direction, a left-to-right or right-to-left direction may be called as a widthwise direction, and an up-to-down or down-to-up direction may be called as a vertical direction. A frontward direction and a rearward direction may be called as a first direction and a second direction, respectively, and the widthwise direction intersects orthogonally with the second direction.

[Overall Configuration of Image Forming Apparatus]

FIG.1is a perspective view of the image forming apparatus1.FIG.2is a cross-sectional view of the image forming apparatus1. An exterior appearance of the image forming apparatus1is provided by a housing2having a form of a substantially rectangular box. The housing2includes a frame (not shown), which supports inner parts, and a cover21, which covers the frame and forms the exterior appearance. The cover21includes a front wall211, which is located on one side in the front-rear direction, a rear wall212, which is located on the other side in the front-rear direction, and an ejection tray213, which is formed on an upper side. The front wall211has an opening21A at a lower position, and the rear wall212has an opening21B at a lower position.

The image forming apparatus1may be a color laser printer, which may form multicolor images on sheets S such as paper sheets and OHP sheets. The housing2accommodates a sheet tray3, a conveyer4, an image forming device5, a duplex conveyer6, and a controller7. In the housing2, the image forming device5is located in an upper and central area, the conveyer4is located in a lower and rearward area with respect to the image forming device5, the duplex conveyer6is arranged in frontward and rearward areas and in a lower area with respect to the conveyer4, and the controller7is located between the image forming device5and the duplex conveyer6.

The sheet tray3has a first outer frame31having a form or a top-open box and includes a sheet storage31A, in which sheets S in a stack may be stored. The first outer frame31has a front wall311located in the opening21A and a rear wall312located in the opening21B.

The front wall311aligns on a plane with the front wall211of the cover21, and the rear wall312aligns on a plane with the rear wall212of the cover21. The rear wall312of the first outer frame31and the rear wall212of the cover21form an outer surface of the image forming apparatus1. The sheet tray3is movable with respect to the housing2to be drawn frontward through the opening21A. The first outer frame31may not necessarily have the form of the top-open box as long as the first outer frame31has the rear wall312, which forms the outer surface of the image forming apparatus1together with the rear wall212of the cover21.

The conveyer4includes parts and members arranged along a conveyer path P1and may convey the sheet S along the conveyer path P1. The conveyer path P1is a path extending from the sheet tray3through the image forming device5to the ejection tray213. The conveyer4includes a feeder41, a belt unit42, and an ejection device43, which are arranged in this given order along the conveyer path P1from upstream to downstream in a conveying direction to convey the sheet S.

The feeder41includes a feed roller411, a separation roller412, a separation pad413, a conveyer roller pair414, and a registration roller pair415. The feed roller411, the separation roller412, and the separation pad413may supply the sheets S from the sheet tray3to the conveyer path P1one by one. The sheet S supplied to the conveyer path P1may be conveyed by the conveyer roller pair414and the registration roller pair415toward the image forming device5.

The belt unit42is detachably attached to the housing2and includes a driving roller421, which may rotate in conjunction with the image forming device5, a driven roller422, which is rotatable at a position separated from the driving roller421, and a conveyer belt423strained around the driving roller421and the driven roller422. The conveyer belt423may circulate, with the sheet S riding thereon, to convey the sheet S along the conveyer path P1through an area below drum units51in the image forming device5to a fuser53.

The ejection device43includes an intermediate ejection roller pair431, which is located between a branch point P11in the conveyer path P1and the ejection tray213, and an ejection roller pair432. The intermediate ejection roller pair431and the ejection roller pair432are switchback rollers, of which rotating directions may be switched between a forward direction and a reverse direction. The intermediate ejection roller pair431and the ejection roller pair432may rotate in the forward direction to eject the sheet S conveyed from the fuser53at the ejection tray213and in the reverse direction to turn the sheet S over and convey the sheet S to the duplex conveyer path P2.

The image forming device5may form images on the sheets S electro-photographically. Optionally, however, the image forming device5may form images on the sheets S in another printing method such as inkjet printing. The image forming device5may be a multicolor printer in a so-called direct-tandem style, having four (4) drum units51aligning in line along the front-rear direction, LED exposure heads52, the fuser53, and a belt cleaner54.

The four drum units51are provided to correspond to toners in four (4) colors, which are black, yellow, magenta, and cyan, on one-to-one basis. Each drum unit51includes a photosensitive drum511, a developing roller512, and a transfer roller513located to face the photosensitive drum511across the conveyer belt423.

In the image forming device5, each photosensitive drum511charged evenly by a charger (not shown) may be selectively exposed to a beam emitted from the exposure LED head52. The exposing beam may selectively remove the charges from surface of the photosensitive drum511, and electrostatic latent images as selected may be formed on the surface of the photosensitive drum511.

To each developing roller512, developing bias is applied. When the electrostatic latent images formed on the photosensitive drum511come to face the respective developing roller512, due to potential difference between the electrostatic latent images and the developing roller512, the toner may be supplied from the developing roller512to the electrostatic latent images. Thus, images in the toner may be formed on the surface of the photosensitive drum511.

The sheet S conveyed to the image forming device5may be further conveyed by the conveyer belt423in the image forming device5through the position between the conveyer belt423and the photosensitive drums511. As the sheet S travels through the position between the conveyer belt423and the photosensitive drums511, the toner images on the photosensitive drums511may be transferred onto the sheet S one by one with transfer bias applied to the transfer rollers513.

The fuser53is located in the conveyer path P1at a position downstream from the photosensitive drums511in the conveying direction. The fuser53includes a heat roller531and a pressure roller532pressed against the heat roller531. The heat roller531is located on a side of the sheet S, on which the image is formed, and may rotate in synchronization with the conveyer belt423to apply a conveying force to the sheet S while heating the toners on the sheet S.

The pressure roller532is located on a side opposite to the heat roller531across the sheet S and may press the sheet S against the heat roller531. The heat roller531may receive a rotating force from the heat roller531through the sheet S contacting the heat roller531and may be rotated.

The fuser53further includes a fuser-ejection roller pair533, which is located downstream from the heat roller531and the pressure roller532in the conveying direction.

As the sheet S with the toner images transferred thereon travels through a position between the heat roller531and the pressure roller532, the toner images may be thermally fixed to the sheet S. The sheet S with the thermally fixed toner images may be nipped by the fuser-ejection roller pair533and conveyed to the intermediate ejection roller pair431.

The belt cleaner54is detachably located at a position between the belt unit42and the duplex conveyer6and may collect waste toners from the conveyer belt423. The belt cleaner54includes a backup roller541, a cleaning roller542, a collection roller543, a scraper blade544, a collection chamber545, and a waste toner box546.

The backup roller541is located on an inner side of the conveyer belt423and contacts an inner upper surface of the belt423. The cleaning roller542is located at a position to face the backup roller541across the conveyer belt423and contacts an outer lower surface of the conveyer belt423.

In the belt cleaner54, the waste toners adhered to the conveyer belt423may be collected by the cleaning roller542, the collection roller543, the scraper blade544, and the collection chamber545, and the collected waste toners may be stored in the waste toner box546.

A cleaning operation may start after images are formed by the image forming device5. Through the cleaning operation, the waste toners adhered to the conveyer belt423may be held electrically on a surface of the cleaning roller542, to which bias is applied, and electrostatically transferred to the collection roller543. The waste toners transferred to the collection roller543may be scraped off from the collection roller543by the scraper blade544and fall in the collection chamber545. The waste toners fallen in the collection chamber545may be conveyed rearward by a conveyer, which is not shown, and stored in the waste toner box546.

The duplex conveyer6includes parts and members arranged along a duplex conveyer path P2and may convey the sheet S along the duplex conveyer path P2. The duplex conveyer path P2branches off from the conveyer path P1at the branch point P11, which is between the fuser53and the intermediate ejection roller pair431, extends through an area above the sheet tray3, and merges with the conveyer path P1at a merge point P12, which is between the sheet tray3and the image forming device5. In this arrangement, the duplex conveyer path P2may be shortened compared to an arrangement, in which the duplex conveyer path P2is arranged below the sheet tray3.

The duplex conveyer6has a lower chute61, which may guide a lower surface of the sheet S, and an upper chute62, which may guide an upper surface of the sheet S, at positions higher than the sheet tray3and lower than the image forming device5. The lower chute61has a skew roller pair611, and a duplex conveyer roller612, and a second outer frame614. The skew roller pair611and the duplex conveyer roller612may guide the sheet S along the duplex conveyer path P2. The second outer frame614supports the skew roller pair611and the duplex conveyer roller612and may guide the lower surface of the sheet S.

The duplex conveyer roller612may nip the sheet S with a driven roller613. The driven roller613is supported by a supporting member416of the feeder41, which is located above the duplex conveyer roller612. The second outer frame614has a rear wall615, which is located in the opening21B. The rear wall615aligns on a plane with the rear wall212of the cover21. The lower chute61may be drawn rearward through the opening21B. The rear wall615of the second outer frame614and rear wall212of the cover21form an outer surface of the image forming apparatus1. A form of the second outer frame614may not necessarily be limited as long as the second outer frame614has the rear wall615, which forms the outer face of the image forming apparatus1together with the rear wall212of the cover21.

The duplex conveyer6may convey the sheet S, having been conveyed by the intermediate ejection roller pair431, with the image formed on one side thereof, to the merge point12. The sheet S conveyed through the merge point P12may return to the image forming device5, and the image forming device5may form an image on the other side of the sheet S. The sheet S with the images formed on the other side may be ejected by the ejection device43at the ejection tray213. When the sheet S is jammed in the duplex conveyer6, a user may draw the lower chute61rearward and remove the jammed sheet S.

Thus, the image forming apparatus1may perform double-face printing, in which the image forming device5may form an image on one side of the sheet S, and the sheet P may be conveyed through the duplex conveyer path P2to return to the image forming device5, and the image forming device5may form another image on the other side of the sheet S.

The controller7has a main circuit board (not shown), a low-voltage circuit board71, a metal plate member72, and a high-voltage circuit board (not shown), which may apply a voltage higher than the low-voltage circuit board71to, for example, the image forming device5.

The main circuit board is located on a leftward side of a frame of the housing2. The main circuit board is a board, on which a controller to control the entire image forming apparatus1, including the low-voltage circuit board71and the higher-voltage circuit board. The low-voltage circuit board71is located at a position rearward with respect to the belt cleaner54and between the duplex conveyer6and the image forming device5. The lower-voltage circuit may apply a lower voltage to, for example, a power circuit.

The metal plate member72is an enclosure that encloses the low-voltage circuit board71in the vertical direction and the front-rear directions. The high-voltage circuit board may be located on a rightward side of the frame of the housing2and may apply the higher voltage to, for example, the image forming device5.

Next, a noise-reducible structure in the image forming apparatus1that may restrain leakage of noise through the rear wall312of the sheet tray3and the rear wall615of the lower chute61will be described below.

[Noise-Reducible Structure]

FIG.3is an enlarged rearward view of a lower area of the rear wall212in the image forming apparatus1.FIG.4is a cross-sectional view of the image forming apparatus1sectioned at line A-A shown inFIG.3.FIG.5is an enlarged plan view of a rearward area in the sheet tray3.

As shown inFIGS.3-5, the first outer frame31of the sheet tray3has a first dent32, a first wall33, and a groove34. As shown inFIGS.3and4, the second outer frame614of the lower chute61includes a second dent63, a handle64, and a second wall65. The second dent63and the first dent32form the opening81.

The sheet tray3includes a stopper35to regulate a position of rearward edges of the sheets S and a stopper lever36, which allows the stopper35to move in the front-rear direction.FIGS.4and5show the stopper35located at a most rearward position. The stopper35, when pinched in the front-rear direction as indicated in dash-and-dots lines inFIG.5, is enabled to move in the front-rear direction. Therefore, the stopper35may be moved to a position corresponding to a size of the sheets S, and by regulating the position of the rear ends of the sheets S, the front ends of the sheets S may align.

As shown inFIGS.3-5, the first dent32may be formed by, for example, cutting the rear wall312through in the front-rear direction at an upper edge312A of the rear wall312of the first outer frame31in a central area in the widthwise direction to dent downward in a substantially rectangular shape. The first dent32has a lower surface321, a left-side surface322extending upward from a leftward end of the lower surface321to an upper edge312A of the rear wall312, and a right-side surface323extending upward from a rightward end of the lower surface321to the upper edge312A of the rear wall312.

The first wall33extends upward from the first dent32. The first wall33includes a first central wall331, a left-side wall332and a right-side wall333which are a pair of side walls located on a leftward side and a rightward side of the first central wall331. The first central wall331extends upward to a substantially half height of the upper edge312A of the rear wall312from the lower surface321of the first dent32at a position apart from the left-side surface322and from the right-side surface323in the widthwise direction.

An upper end of the first central wall331is located to be lower than a lower end of the feed roller411and lower than an upper end of the stopper lever36. The first central wall331is located apart frontward from a rear end of the first dent32by a predetermined distance. In other words, the first central wall331is located inward with respect to the opening81.

The left-side wall332extends upward to a position higher than the upper edge312A of the rear wall312of the first outer frame31from the lower surface321of the first dent32to shield a gap between the leftward end of the first central wall331and the left-side surface322of the first dent32. The right-side wall333extends upward to a position higher than the upper edge312A of the rear wall312of the first outer frame31from the lower surface321of the first dent32to shield a gap between the rightward end of the first central wall331and the right-side surface323of the first dent32.

Positions of an upper end of the left-side wall332and an upper end of the right-side wall333may not necessarily be limited as long as the upper ends of the left-side wall332and the right-side wall333are located to be higher than the upper end of the central wall331. The left-side wall332and the right-side wall333are located on one side and the other side of the feed roller411, respectively, in the widthwise direction. In other words, the left-side wall332is located leftward from the feed roller411, and the right-side wall333is located rightward from the feed roller411. A rear end of the left-side wall332and a rear end of the right-side wall333align on a plane with the rear end of the first central wall331. A front end of the left-side wall332and a front end of the right-side wall333align on a plane with a front end of the groove34.

The left-side wall332and the right-side wall333have slanting surfaces334,335, which slant lower toward the opening81, i.e., rearward, from the upper ends thereof. The upper ends of the slanting surfaces334,335are located at the same position in the front-rear direction as an upper-front end of the first central wall331.

As shown inFIGS.4and5, the groove34is open upward and is located between the first central wall331and the stopper lever36in the front-rear direction and between the left-side wall332and the right-side wall333in the widthwise direction. The groove34has a slanting surface341, which slants lower-frontward from a lower-frontward end of the first central wall331, and a bottom surface342, which extends horizontally frontward from a lower end of the slanting surface341to a position rearward from the stopper lever36.

As shown inFIGS.3and4, the second dent63may be formed by, for example, cutting the rear wall615through in the front-rear direction at a lower edge615A of the rear wall615of the second outer frame614in a central area in the widthwise direction to dent upward in a substantially rectangular shape. The second dent63faces the first dent32in the vertical direction. The second dent63has an upper surface631extending frontward and slanting lower-frontward, a left-side surface632extending downward from a leftward end of the upper surface631to a lower edge615A of the rear wall615, and a right-side surface633extending downward from a rightward end of the upper surface631to the lower edge615A of the rear wall615.

The handle64is a member extending downward from the second dent63. The handle64is a plate member extending from the rear end of the upper surface621of the second dent63downward along the left-side surface632and the right-side surface633to a position to shield a substantially upper half of the second dent63. The handle64is formed to align on a plane and integrally with the rear wall615of the second outer frame614. As illustrated in dash-and-dots lines inFIG.4, the user may insert his/her fingers from a lower side of the handle64to touch a frontward surface of the handle64and pull the handle64rearward. Thereby, the lower chute61may be drawn rearward.

As shown inFIGS.3and4, the second wall65extends downward from the second dent63. The second wall65is located frontward from the handle64and the first central wall331and rearward from the stopper lever36. The second wall65may extend downward from a position on the upper surface631of the second dent63substantially equal to a lower end of the handle64. The second wall65has a second central wall651, a left-side wall652and a right-side wall653, which are located on one side and the other side of the second central wall651in the widthwise direction.

The second central wall651is located between the left-side wall652and the right-side wall653in the widthwise direction. A lower end of the second central wall651is located to be lower than the upper ends of the left-side wall652and the right-side wall653and higher than the upper end of the stopper lever36.

The left-side wall652extends downward to a position substantially equal to the lower edge615A of the rear wall615of the second outer frame614from the upper surface631of the second dent63to shield a gap between the leftward end of the second central wall651and the left-side surface632of the second dent63. The right-side wall653extends downward to a position substantially equal to the lower edge615A of the rear wall615of the second outer frame614from the upper surface631of the second dent63to shield a gap between the rightward end of the second central wall651and the right-side surface633of the second dent63.

The positions of the lower ends of the left-side wall652and the right-side wall653may not necessarily be limited as long as the lower ends of the left-side wall652and the right-side wall653are located to be higher than the upper ends of the left-side wall332and the right-side wall333of the first wall33.

The first wall33and the second wall65are located on the first outer frame31and the second outer frame614, respectively, frontward with respect to the handle64and shield some areas in the opening81. In this regard, one of the first wall33and the second wall65may be omitted as long as the one of the first wall33and the second wall65is located frontward with respect to the handle64and shields an area in the opening81. In this arrangement, the first wall33and/or the second wall65may restrain leakage of noise that may be produced by conveying the sheets S and noise from motors through the opening81.

According to the configuration described above, the upper end of the first central wall331is located to be lower than the lower end of the feed roller411, and the left-side wall332and the right-side wall333are located on one side and the other side of the feed roller441in the widthwise direction. In this arrangement, while the first wall33may be restrained from colliding with the feed roller411when the sheet tray3is drawn frontward, the noise may be restrained from leaking more effectively. While the left-side wall332and the right-side wall333are arranged not to collide with the feed roller411, the upper ends of the left-side wall332and the right-side wall333may be extended upward to positions in the vicinity of the lower ends of the left-side wall652and the right-side wall653.

According to the configuration described above, the upper end of the first central wall331is located to be lower than the upper end of the stopper lever36. With the height of the first central wall331being smaller, the first central wall331may not interfere with the user's fingers hooking to the handle64or may not interfere with the lower chute61when the sheet tray3is being drawn frontward.

According to the configuration described above, the left-side wall332and the right-side wall333have slanting surfaces334,335, which slant lower-rearward from the upper ends thereof. Therefore, the left-side wall332or the right-side wall333may not interfere with the user's fingers hooking to the handle64.

According to the configuration described above, the upper ends of the left-side wall332and the right-side wall333are located to be higher than the upper edge312A of the rear wall312of the first outer frame31. In this arrangement, the opening81may be effectively shielded.

According to the configuration described above, the sheet tray3has the groove34, which is open upward, between the first central wall331and the stopper lever36. Therefore, the user's fingers may enter the space formed with the groove34easily to pinch the stopper lever36from the upper side.

According to the configuration described above, the lower chute61has the second wall65to shield the opening81more effectively. Moreover, the lower end of the second central wall651is located to be lower than the upper ends of the left-side wall332and the right-side wall333and higher than the upper end of the first central wall331. In this arrangement, while the second central wall651may not collide with the sheet tray3, the noise may be restrained from leaking effectively.

According to the configuration described above, the second wall65is located between the first central wall331and the stopper lever36in the front-rear direction. In this arrangement, the space to allow entry of the user's fingers to be hooked with the handle64may be reserved between the handle64and the second wall65, and the second wall65may be restrained from interfering with the fingers.

While the invention has been described in conjunction with various example structures outlined above and illustrated in the figures, various alternatives, modifications, variations, improvements, and/or substantial equivalents, whether known or that may be presently unforeseen, may become apparent to those having at least ordinary skill in the art. Accordingly, the example embodiments of the disclosure, as set forth above, are intended to be illustrative of the invention, and not limiting the invention. Various changes may be made without departing from the spirit and scope of the disclosure. Therefore, the disclosure is intended to embrace all known or later developed alternatives, modifications, variations, improvements, and/or substantial equivalents. Some specific examples of potential alternatives, modifications, or variations in the described invention are provided below.

For example, the chute that may be drawn rearward may not necessarily be limited to the lower chute61, but the upper chute62may be the chute to be drawn rearward. In this arrangement, the rear wall615of the lower chute61may not be located in the opening21B, but the rear wall of the upper chute62may be located in the opening21B while the handle64and the second dent63may be arranged in the rear wall of the upper chute62. For another example, both the upper chute62and the lower chute61may be drawn rearward either integrally or individually.