Document Conveying Device

This application is based on and claims the benefit of priority from Japanese patent application No. 2024-046577 filed on Mar. 22, 2024, which is incorporated by reference in its entirety.

The present disclosure relates to a document conveying device.

A document conveying device for conveying a document to a reading position of an image reading device is known. The document conveying device includes, for example, a sheet feeding tray on which the documents are placed, a discharge tray provided below the sheet feeding tray, and a conveying mechanism for conveying the document from the sheet feeding tray to the discharge tray via the reading position of the document reading device.

The convenience of the document conveying device increases as a capacity (an amount of the documents that can be placed) of the sheet feeding tray and the discharge tray increases. Therefore, a technique for realizing a large-capacity document conveying device has been studied. For example, there is an apparatus in which the sheet feeding tray is configured to be lifted and lowered in the upper-and-lower direction in parallel, so that a sheet placed space of the discharge sheet between the discharge tray and the sheet feeding tray is expanded by lifting the sheet feeding tray as the sheet placed on the sheet feeding tray is conveyed to the discharge tray.

By the way, the document conveying device generally includes a wall part with which the downstream end portion of the document on the sheet feeding tray in the sheet feeding direction is into contact. In order to increase a capacity of the sheet feeding tray, it is necessary to increase a size of the wall part in the upper-and-lower direction, but in this case, a size of the document conveying device in the upper-and-lower direction also increases.

A document conveying device according to the present disclosure includes a sheet feeding tray, a sheet feeding mechanism, a sheet feeding tray lifting mechanism, a top plate, a fixed wall part, and a lifting wall part. On the sheet feeding tray, a document is placed. The sheet feeding mechanism feeds the document placed on the sheet feeding tray in a predetermined sheet feeding direction. The sheet feeding tray lifting mechanism lifts and lowers the sheet feeding tray. The top plate is adjacent to the sheet feeding tray on a downstream side in the sheet feeding direction, and is in contact with a lower surface of the document to be fed. The fixed wall part is provided extending downward from an upstream side end portion of the top plate in the sheet feeding direction, and fixed in position. The lifting wall part is provided extending upward from a downstream side end portion of the sheet feeding tray in the sheet feeding direction, faces the fixed wall part on an upstream side of the fixed wall part in the sheet feeding direction, and is lifted and lowered along the fixed wall part together with the sheet feeding tray. The lifting wall part has a slit along an upper-and-lower direction. The fixed wall part has a fin along the upper-and-lower direction. An upper end portion of the slit is opened in the upper-and-lower direction. The fin protrudes upstream of the sheet conveying direction, and is arranged inside the slit.

The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present disclosure is shown by way of illustrative example.

Hereinafter, with reference to the drawings, a document conveying deviceand an image forming apparatusaccording to one embodiment of the present disclosure will be described.

First, the overall configuration of the image forming apparatuswill be described.is a front view schematically showing the internal structure of the image forming apparatus. Hereinafter, the front side of the paper plan on whichis drawn is defined as the front side of the image forming apparatus, and the right-and-left directions will be described with reference to the direction in which the image forming apparatus is viewed from the front side. In each figure, U, Lo, L, R, Fr, and Rr indicate the upper, lower, left, right, front, and rear, respectively.

The image forming apparatusincludes a recording device, an image reading device, and a document conveying device. The image reading deviceis provided above the recording device, and the document conveying deviceis provided above the image reading device. The document conveying deviceconveys a document G via a reading position A of the image reading device. The image reading deviceis a flatbed type image reading device, and reads the document G to generate image data. The recording deviceforms an image on a sheet S based on the image data. In this embodiment, the recording deviceforms the image in an electrophotographic system, but the recording devicemay be configured to form an image in another system (for example, an inkjet system).

The recording deviceincludes a rectangular parallelepiped body housing. In the lower portion in the body housing, a sheet feeding cassettein which the sheet S is housed and a sheet feeding rollerwhich feeds the sheet S rightward from the sheet feeding cassetteare provided. Above the sheet feeding cassette, an image forming devicewhich forms a toner image in an electrophotographic manner is provided, and a fixing devicewhich fixes the toner image to the sheet S is provided in the right and upper side of the image forming device. Above the fixing device, a discharge rollerwhich discharges the sheet S to which the toner image is fixed and a discharge trayon which the discharged sheet S is stacked are provided.

Inside the body housing, a conveyance pathfrom the sheet feeding rollerthrough the image forming deviceand the fixing deviceto the discharge rolleris provided. The conveyance pathis formed mainly of plate-like members facing each other with a gap for passing the sheet S, and a conveyance rollerfor holding and conveying the sheet S is provided at a plurality of positions in the conveyance direction Y. A registration rolleris provided on the upstream side of the image forming devicein the conveyance direction Y. On the right side of the fixing device, there is provided an inversion conveyance pathR which branches from the conveyance pathon the downstream side of the fixing devicein the conveyance direction Y and merges with the conveyance pathon the upstream side of the registration rollerin the conveyance direction Y.

A control partincludes an arithmetic part and a storage part (not shown). The arithmetic part is, for example, a CPU (Central Processing Unit). The storage part includes a storage medium such as ROM (Read Only Memory), RAM (Random Access Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory). The arithmetic part reads and executes control program stored in the storage part to perform various processes. The control partmay be implemented only by an integrated circuit without using software.

A display operation part (not shown) is provided on the front side of the image reading device. The display operation part is provided with a display panel, a touch panel superposed on the display surface of the display panel, and a keypad adjacent to the display panel (not shown). The control partdisplays a screen showing an operation menu and a status of the recording deviceand the image reading deviceon the display panel, and controls each part of the recording deviceand the image reading deviceaccording to an operation detected by the touch panel and the keypad.

The basic image forming operation of the recording deviceis as follows. When a single-sided printing job is input to the recording devicefrom the display operation part or an external computer, the sheet feeding rollerfeeds the sheet S from the sheet feeding cassetteto the conveyance path, the registration rollerwhose rotation is stopped corrects the skew of the sheet S, and the registration rollerfeeds the sheet S to the image forming deviceat a predetermined timing. The image forming deviceforms a toner image on the sheet S by the electrophotographic method. Subsequently, the fixing devicefixes the toner image to the sheet S by melting the toner image while holding and conveying the sheet S, and the discharge rollerdischarges the sheet S to the discharge tray. In the case of double-sided printing, the sheet S on which the toner image is fixed on the first surface is fed to the conveyance pathvia the inversion conveyance pathR, whereby the toner image is transferred to the second surface.

[Image Reading Device] The image reading deviceincludes a first carriageincluding a light source and a reflecting mirror, a second carriageincluding two reflecting mirrors, a lensfor forming an image with light, an imaging elementfor converting the formed light into image data, and a contact glasson which the document G is placed.

The basic document reading operation of the image reading deviceis as follows. When the user places the document G on the upper surface of the contact glassand gives a reading instruction to the image reading device, the first carriagemoves rightward at a speed V while the second carriagemoves rightward at a speed V/2. During this time, the light source irradiates the document G with light, and the reflected light reflected by the document G is reflected by the reflecting mirror of the first carriageand the reflecting mirrors of the second carriage, is guided to the lens, forms an image on the imaging element, and is converted into an image signal. The image signal is output to the control partof the recording deviceand converted into the image data.

[Document Conveying Device] Next, the document conveying devicewill be described.is a perspective view showing an external appearance of the document conveying device.is a front view schematically showing a sheet feeding mechanismand a conveying mechanism.andare front views schematically showing the conveying mechanismand a sheet feeding tray lifting mechanism.is a rear view schematically showing the sheet feeding tray lifting mechanism.,, andshow a state in which a sheet feeding trayis positioned near the upper limit position, andshows a state in which the sheet feeding trayis positioned near the lower limit position.

The document conveying device(seeand) includes a generally rectangular bottom portionformed in a flat shape, and a first wall portionand a second wall portionfacing each other in the front-and-rear direction (the width direction intersecting the sheet feeding direction Z of the document G). The rear edge portion of the bottom portionis hinged on the rear side of the contact glass(see) of the image reading device. The bottom portionalso has a function of holding the document G on the contact glass. The first wall portionis provided from the left end portion to the center portion of the front edge portion of the bottom portion. The second wall portionis provided over the entire area of the rear edge portion of the bottom portion. A cover portioncovers the upper and left sides of the space between the first wall portionand the second wall portion. The left lower end portion of the cover portionis hinged to the left end portion of the bottom portion.

[Sheet Feeding Tray] A sheet feeding tray(seeand) is provided on the right side of the center of the document conveying devicein the left-and-right direction and on the front side of the second wall portion. The sheet feeding trayis a plate-like member inclined such that the left side is lowered. On the upper surface of the sheet feeding tray, a pair of cursorsfor aligning the front and rear ends of the document G are provided. The cursoris slidable in the front-and-rear direction.

[Discharge Tray] A discharge trayis provided below the sheet feeding tray. The discharge trayis integral with the bottom portion.

[Sheet Feeding Mechanism] A sheet feeding mechanism(see) is provided in the space between the first wall portionand the second wall portion. The sheet feeding mechanismis provided with a box-shaped holderwhose lower portion is opened. Inside the holder, a pickup roller, a driven roller, a driving roller, and a retard rollerare arranged with their axial directions along the front-and-rear direction. The driven rolleris provided on the left side of the pickup roller. The driving rolleris provided on the left side of the driven roller. An endless beltis wound around the driving rollerand the driven roller. The retard rolleris pressed against the lower surface of the lower portion of the endless belt.

Both front and rear ends of a driving shaftof the driving rollerare supported by the first wall portionand the second wall portion, and are connected to a drive part (not shown) including a motor and a reduction gear. The holderis supported by the driving shaft, and can be turned around the driving shaft. A driving force is transmitted from the driving shaftto the pickup rollerand the retard rollerby a transmission mechanism (not shown) such as a gear train or an endless belt.

A sensoris a transmission type or a reflection type optical sensor, and is provided on the inner surface of the cover portion. A light shielding plateprotruding upward or sideways is provided on the upper portion of the holder. The sensoroutputs detection signals having different level to the control partwhen the light shielding plateblocks the light of the sensorand when the light shielding plate does not block the light.

[Sheet Feeding Tray Lifting Mechanism] A sheet feeding tray lifting mechanism(seeand) is provided on the front surface of the first wall portionand the rear surface of the second wall portion. A driving pulleyand a driven pulley(see) are provided at the upper and lower portions of the central portion of the rear surface of the second wall portion, respectively. A driven pulleyis provided at an intermediate height between the driving pulleyand the driven pulleyand on the left side of the driving pulleyand the driven pulley. A guide pulleyis provided on the left upper side of the driven pulleyand on the right side of the driven pulley. An endless beltis wound around the driving pulley, the driven pulleysand, and the guide pulley. A driving partincludes a motorM, a worm gearW, an idler gear, and a driving gearG. The driving gearG is provided on the shaft of the driving pulley.

Driven pulleys,,, and the guide pulley(see) are provided on the front surface of the first wall portionat positions facing the driving pulley, the driven pulleys,, and the guide pulley, respectively. An endless beltis wound around the driven pulleys,,and the guide pulley. The driven pulleyis provided on the common shaft with the driven pulley.

A sliding part(see) is provided at the left end portion of the rear edge portion of the sheet feeding tray. The second wall portionis provided with a slitS whose longitudinal direction is along the upper-and-lower direction. The slitS is provided at a position corresponding to the left end portion of the rear edge portion of the sheet feeding tray. The sliding partpenetrates the slitS, and is coupled to the endless beltbetween the driving pulleyand the driven pulley.

A lifting guide partis provided on the rear surface of the second wall portion. The lifting guide partis a rail-like member whose longitudinal direction is along the upper-and-lower direction. The sliding partis slidable in the upper-and-lower direction along the lifting guide part.

A sliding part(see) is provided at the left end portion of the front edge portion of the sheet feeding tray. The sliding partis coupled to the endless beltbetween the driven pulleyand the driven pulley.

A lifting guide partis provided on the front surface of the first wall portion. The lifting guide partis a rail-like member whose longitudinal direction is along the upper-and-lower direction. The sliding partis slidable in the upper-and-lower direction along the lifting guide part.

The basic operation of the sheet feeding tray lifting mechanismis as follows. A driving force generated by the motorM is transmitted to the driving gearG via the worm gearW and the idler gear. The driving pulleyis rotated together the driving gearG, the endless belttravels, and the driven pulleysandare rotated accordingly. The driven pulleyis rotated together with the driven pulley, and the endless belttravels synchronously with the endless belt. Since the sheet feeding trayis coupled to the endless belts,via the sliding parts,, the sheet feeding trayis lifted and lowered by the forward and reverse rotations of the motorM.

The control partcontrols the sheet feeding tray lifting mechanismto lift the sheet feeding tray. When the upper surface of the document G placed on the sheet feeding trayis pressed against the pickup roller, the holderis turned upward. When the holderis turned upward by a predetermined amount, the light shielding plateblocks the light of the sensor. At this time, an appropriate load acts between the upper surface of the document G and the pickup roller, and the document G can be fed by the pickup roller. In other words, the control partcontrols the sheet feeding tray lifting mechanismso as to lift the sheet feeding trayas an amount of documents G placed on the sheet feeding traydecreases.

[Conveying Mechanism] A conveying mechanism(see) includes a conveyance pathextending from the sheet feeding mechanismto the discharge rollervia an openingA, and a plurality of conveying rollersarranged in the conveyance path. The conveyance pathis formed mainly of plate-like members facing each other with a gap through which the document G can pass. The openingA is a slit provided in the bottom portionat a region facing the first carriage(see) located at the home position and whose longitudinal direction is along the front-and-rear direction. The openingA is an example of the reading position A where the image reading devicereads the document G. At the reading position A, an openingA corresponding to the openingA is provided in a plate-like member on the lower side of the conveyance path, and the lower surface of the document G being conveyed is exposed downward through the openingsA andA.

The conveying rollerincludes a driving rollerD and a driven rollerN (see). A driven pulleyN (see) is provided on the shaft of the driving rollerD. A driving pulleyD is connected to a driving part (not shown) including a motor and a reduction gear. An endless beltis wound around the driving pulleyD, the driven pulleysN, and a guide pulleyG. When the driving pulleyD is driven, the endless beltis traveled and the driven pulleysN are rotated synchronously, so that the conveying rollersare also rotated synchronously.

A guide part() is provided in the conveyance pathon the downstream side of the openingA in the sheet feeding direction Z. The guide partis formed by integrating plate-like members facing in the upper-and-lower direction, and is turned around the driving rollerD or the driven rollerN of the conveying rolleradjacent to the right side of the openingA. A description of the mechanism for turning the guide partis omitted.

[Structure of Fixed Wall Part and Lifting Wall Part] Next, a fixed wall partand a lifting wall partwill be described.toare perspective views showing the fixed wall part, the lifting wall part, and the sheet feeding tray.shows a state where the lifting wall partand the sheet feeding trayare positioned at the lower limit position.shows a state in which the lifting wall partis positioned at the upper limit position and the sheet feeding trayis positioned at the intermediate position.shows a state in which the lifting wall partis positioned at the upper limit position and the sheet feeding trayis positioned at the upper limit position.andare disassembled views showing the fixed wall partand the lifting wall part.

The document conveying deviceincludes the sheet feeding trayon which the document G is placed, the sheet feeding mechanismwhich feeds the document G placed on the sheet feeding trayin the predetermined sheet feeding direction Z, the sheet feeding tray lifting mechanismwhich lifts and lowers the sheet feeding tray, a top plateadjacent to the sheet feeding trayon the downstream side in the sheet feeding direction Z and in contact with the lower surface of the document G to be fed, the fixed wall partprovided extending downward from the upstream end portion of the top platein the sheet feeding direction Z and fixed in position, and the lifting wall partprovided extending upward from the downstream end portion of the sheet feeding trayin the sheet feeding direction Z and lifting/lowering along the fixed wall parttogether with the sheet feeding tray.

[Top Plate] The top plate(seeto) is provided generally horizontally. An openingA is provided at the center of the top platein the front-and-rear direction. The retard rollerincluded in the sheet feeding mechanismis disposed in the openingA. The document G fed by the pickup rolleris conveyed along the upper surface while bringing its lower surface into contact with the upper surface of the top plate.

[Fixed Wall Part] The fixed wall partis a rectangular member whose longitudinal direction is along the front-and-rear direction as a whole, and is provided in a posture downwardly upright from the upstream end portion of the top platein the sheet feeding direction Z, and is integrated with the top plate. The fixed wall partincludes a plurality of convex portionsT,T,T,T,T,T, andT, and a plurality of concave portionsU,U,U,U,U, andU. The convex portionsTtoTare provided at intervals along the upstream end portion of the top platein the sheet feeding direction Z, protrude toward the sheet feeding tray, and have a hollow structure with the lower end portion opened. The concave portionsUtoUare alternately provided with the convex portionsTtoT. The convex portionT, the concave portionU, the convex portionT, the concave portionU, the convex portionT, the concave portionU, the convex portionT, the concave portionU, the convex portionT, the concave portionU, the convex portionT, the concave portionU, and the convex portionTare arranged in this order from the front side.

Each of the convex portionsTtoTis formed in a substantially rectangular parallelepiped shape having a smaller dimension in the left-and-right direction than the upper-and-lower direction. The upper end portions of the convex portionsTtoTand the concave portionsUtoUare inclined so that the downstream side in the sheet feeding direction Z becomes higher. Shapes and dimensions of the convex portionsTtoTmay be different from each other as shown, but may be the same. Shapes and dimensions of the concave portionsUtoUmay be different from each other as shown, but may be the same.

[Restriction Part] Side wall partsW are provided extending downwardly upright from both front and rear end portions of the top plate. The side wall partsW are integrated with the top plateand the fixed wall part. A restriction partR is a slit provided in the side wall partW along the upper-and-lower direction. The upper end of the restriction partR is closed, and the lower end is opened.

[Lifting Wall part] A bottom platefaces the top platebelow the top plate. The lifting wall partis provided extending upwardly upright from the upstream end portion of the bottom platein the sheet feeding direction Z, and is integrated with the bottom plate. The lifting wall partincludes a plurality of convex fitting portionsT,T,T,T,T,T, andT, and a plurality of concave fitting portionsU,U,U,U,U, andU. The convex fitting portionsT,T,T,T,T,T, andTare fitted inside the convex portionsT,T,T,T,T,T, andT, respectively. The concave fitting portionsU,U,U,U,U, andUare fitted inside the concave portionsU,U,U,U,U, andU, respectively. With the lifting and lowering of the sheet feeding tray, the convex fitting portionsTtoTslide along the convex portionsTtoT, and the concave fitting portionsUtoUslide along the concave portionsUtoU.

[End Portion] The front and rear end portionsE of the lifting wall partare inserted into the restriction partsR, and slide along the restriction partsR. Since the upper end portion of the restriction partR is closed, when the end portionE comes into contact with the upper end portion of the restriction partR, the lifting of the lifting wall partis stopped. When the end portionE comes into contact with the upper end portion of the restriction partR, the upper end portion of the lifting wall partbecomes the same height as the upper end portion of the fixed wall part. ProtrusionsB protrude in the front-and-rear direction from the front and rear end portionsE of the lifting wall part.

[Biasing Member] A biasing member(seeand) is a tension coil spring disposed between the top plateand the bottom platein an upright posture. The upper end of the biasing memberis attached to the lower surface of the top plate, and the lower end is attached to the upper surface of the bottom plate. Since the top plateis fixed, the bottom plateand the lifting wall partare biased upward.

[Engagement Part]is a perspective view showing the front portions of the fixed wall part, the lifting wall part, the sheet feeding tray, and the discharge tray.is a perspective view showing a cross section of the front portions of the lifting wall part, the sheet feeding tray, and the discharge tray.is a perspective view showing the discharge tray.is a perspective view showing an engagement partR.is a perspective view showing a cross section of the engagement partR.

Since the lifting wall partis biased upward by the biasing memberas described above, the protrusionB is pressed against the recess portionG. With this configuration, the lifting of the lifting wall partis restricted, and the lifting wall partis kept in a state of protruding upward by a predetermined height from the downstream end portion of the sheet feeding trayin the sheet feeding direction Z.

Next, the operation of this embodiment will be described. When the lifting wall partis positioned at the lower limit position (see), the upper end portion of the lifting wall partis positioned slightly above the lower end portion of the fixed wall part, so that a gap in the upper-and-lower direction does not occur between the lifting wall partand the fixed wall part. In this case, a height of the wall formed by the lifting wall partand the fixed wall partbecomes maximum, and a capacity of the sheet feeding tray(an amount of the document G that can be placed) becomes maximum.

Since the lifting wall partis biased upward by the biasing member, when the sheet feeding trayis lifted by the sheet feeding tray lifting mechanism, the lifting wall partis also lifted together with the sheet feeding tray. At this time, the convex fitting portionsTtoTof the lifting wall partslide along the convex portionsTtoTof the fixed wall part, and the concave fitting portionsUtoUof the lifting wall partslide along the concave portionsUtoUof the fixed wall part.

When the front and rear end portionsE of the lifting wall partare in contact with the upper end portions of the restriction partsR (see), the lifting of the lifting wall partis stopped, and the lifting wall partreaches the upper limit position. At this time, the sheet feeding trayis positioned at the intermediate position between the lower limit position and the upper limit position. When the sheet feeding trayis lifted further, the recess portionsG of the engagement partR are separated from the protrusionsB of the lifting wall part, and only the sheet feeding trayis lifted.

When the sheet feeding trayreaches the upper limit position (see), the downstream end portion of the upper surface of the sheet feeding trayin the sheet feeding direction Z is positioned slightly below the upper surface of the top plate. In this case, a height of the wall formed by the lifting wall partand the fixed wall partbecomes minimum, and a capacity of the sheet feeding traybecomes minimum. As described above, since the upper end portions of the convex portionsTtoTand the concave portionsUtoUof the fixed wall partare inclined so that the downstream side in the sheet feeding direction Z becomes higher, the document G is smoothly fed from the sheet feeding traytoward the top plate.