SHEET CONVEYING APPARATUS AND IMAGE FORMING SYSTEM

According to an embodiment, a sheet conveying apparatus includes a roller conveying mechanism, a sheet conveying sensor, an aligning mechanism, and a conveying controller. The conveying controller causes the paper feed roller of the roller conveying mechanism to be driven to convey the sheet. Furthermore, the conveying controller causes the adjustment roller of the aligning mechanism to be driven on the basis of a detection output of the sheet conveying sensor such that a deviation between the course of the sheet and a predetermined standard course is corrected.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2018-021388, filed on Feb. 8, 2018, the entire contents of which are incorporated herein by reference.

FIELD

An embodiment to be described here generally relates to a sheet conveying apparatus and an image forming system.

BACKGROUND

For example, an image forming system has a sheet conveying apparatus such as an original document conveying apparatus, an automatic paper feeding apparatus, and a manual feeding paper feeding apparatus. The sheet conveying apparatus has guide fences for feeding sheets in a predetermined conveying direction. The sheets are aligned by the guide fences in the conveying direction. After the sheets are aligned, the sheet conveying apparatus starts to feed the sheets. However, if the sheets get out from the guide fences of the sheet conveying apparatus, a sheet course (conveying direction) may be changed. For example, if the conveying direction of conveying rollers is tilted in latter parts of the guide fences with respect to the conveying direction of the aligned sheets, the conveying direction of the sheets is tilted. If conveyance resistance of a conveying path of the sheets varies in a direction orthogonal to the conveying direction of the sheets, the sheet course is curved. The sheet conveying apparatus has a resist mechanism. Even if the sheets skew during conveyance, edge positions of the sheets are aligned by the resist mechanism. However, skewed sheets may be twisted between the resist mechanism and a paper feeding mechanism. Twisting of the sheets may cause creases. Furthermore, the resist mechanism cannot correct horizontal deviation of the sheets in the direction orthogonal to a sheet conveying direction.

DETAILED DESCRIPTION

According to an embodiment, a sheet conveying apparatus includes a roller conveying mechanism, a sheet conveying sensor, an aligning mechanism, and a conveying controller. The roller conveying mechanism conveys the sheet by causing the sheet to come in contact with at least one paper feed roller. The sheet conveying sensor detects a course of the sheet conveyed by the roller conveying mechanism. The aligning mechanism has at least one adjustment roller that corrects the course of the sheet, conveys the sheet, and aligns an edge position of the sheet. The conveying controller causes the paper feed roller of the roller conveying mechanism to be driven to convey the sheet. Furthermore, the conveying controller causes the adjustment roller of the aligning mechanism to be driven on the basis of a detection output of the sheet conveying sensor such that a deviation between the course of the sheet and a predetermined standard course is corrected.

Hereinafter, the sheet conveying apparatus and the image forming system according to an embodiment will be described with reference to the drawings. In the drawings, the same symbols denote the same or similar parts.FIG. 1schematically shows a configuration example of an image forming system100including sheet conveying apparatuses1,2,3according to the embodiment.FIG. 2schematically shows a configuration example of a manual paper feeding device106of the sheet conveying apparatus1according to the embodiment.FIG. 3schematically shows a configuration example of a manual paper feeding device106and peripherals.FIG. 4schematically shows a configuration example of a roller conveying mechanism43and peripherals of the sheet conveying apparatus1according to the embodiment.FIG. 5AandFIG. 5Bschematically show a configuration example of main parts of a second contact/separate mechanism44A.FIG. 6Ashows a configuration example of a course correcting unit46of the sheet conveying apparatus1according to the embodiment.FIG. 6Bis a sectional view taken along A-A ofFIG. 6Aand shows course correcting rollers46A and46B of the course correcting unit46.FIG. 7AandFIG. 7Bschematically show a configuration example of main parts of a first contact/separate mechanism48of the sheet conveying apparatus1according to the embodiment. In the above-mentioned drawings, the size and the shape of each member are exaggerated or simplified for ease of view (the same applies to the following drawings).

The image forming system100according to the embodiment shown inFIG. 1is, for example, an MFP (Multi-Function Peripherals). The image forming system100may be a printer, a copy machine, or the like. The image forming system100includes a scanner101, an ADF (Auto Document feeder)102, a printer103, a paper feeding device104, an inverting device105, a manual paper feeding device106, and a controller110. Note that, in the following description, the configuration of the image forming system100will be described on the basis of an arrangement position ofFIG. 1. The image forming system100ofFIG. 1is arranged on a horizontal plane. The longitudinal direction ofFIG. 1corresponds to the vertical direction. In the image forming system100ofFIG. 1, a front part of the system corresponds to a front ofFIG. 1. Viewed from the direction facing to the front part of the image forming system100, the right side shown corresponds to the right side of the image forming system10. Viewed from the direction facing to the front part of the image forming system100, the left side shown corresponds to the left side of the image forming system100. In the image forming system100ofFIG. 1, a back part of the system faces to the back side ofFIG. 1. In the following description, unless otherwise specified, in relation to relative positions of the members forming the image forming system100, terms of “front”, “back”, “up”, “down”, “left”, “right”, and the like are used on the basis of the arrangement position of the above-described image forming system100ofFIG. 1. Accordingly, the terms of “front”, “back”, “up”, “down”, “left”, “right”, and the like in the following description may be different from the shown positional relationship inFIG. 1.

The scanner101reads an original document (not shown). At the top of the scanner101, there is an original document plate101aon which the original document is placed. On the original document plate101a,an ADF102is provided. The ADF102conveys the original document placed on an original document placing tray102ato an original document reading position (not shown) of the scanner101. After the original document is conveyed to the original document reading position, the original document is ejected to an original document discharging plate102blocated downward the original document placing tray102a.

The scanner101includes an illumination light source (not shown) that illuminates the original document and an image sensor (not shown) that photoelectrically converts reflected light from the original document. The scanner101reads information of the original document fed to the original document reading position by the ADF102or the original document placed on the original document plate101ausing the illumination light source and the image sensor. Though not shown, at a front of the scanner101in the drawing, there is provided an operation device (operation unit) by which an operator operates actions of the image forming system100. For example, the operation device has an operation panel including a variety of keys or a touch panel type display.

Downward the scanner101, a printer103(image forming system body) and a paper feeding device104are provided in this order. The paper feeding device104feeds sheets P to be imaged to the printer103. A direction of the sheets P moving within a paper feeding cassette104adescribed later in order to feed the sheets P to the printer103by the paper feeding device104is referred to as a “first paper feeding direction” in the following description. In the example ofFIG. 1, the first paper feeding direction is a direction from the left side to the right side in the drawing. A direction orthogonal to the first paper feeding direction in a sheet plane of each sheet P is referred to as a first paper feeding orthogonal direction in the following description. The paper feeding device104has the paper feeding cassette104a.The paper feeding device104ofFIG. 1is provided with one paper feeding cassette104aas an example. However, the paper feeding device104may be provided with a plurality of the paper feeding cassettes104a.The paper feeding cassette104ais capable of holding a variety of sizes of the sheets P. In addition, the paper feeding cassette104aholds the sheets P on a center basis. In other words, the sheets P are held in the paper feeding cassette104asuch that a center axis line in a width of each sheet in the first paper feeding orthogonal direction is aligned at a fixed position. Furthermore, the paper feeding device104has a paper feed roller104b.The paper feed roller104bmoves the sheet P to the first paper feeding direction in the paper feeding cassette104aand feeds the sheet P from the paper feeding cassette104ato a conveying path of the printer103. At this time, the paper feeding device104feeds the sheets P one by one separately. A method of feeding the sheets P by the paper feeding device104is not especially limited as long as the sheets P are fed by a roller paper feeding system. Similarly, a method of separating the sheets P is not especially limited. As the method of separating the sheets P, an appropriate separation system such as a corner pawl system, a separation pad system, and a separation roller system may be used, for example. The paper feeding device104includes a variety of rollers, pad members, and the like other than the paper feed roller104bcorresponding to the paper feeding system and the separation system.

The printer103forms images on the sheets P on the basis of image data of the original document read by the scanner101or image data generated by a personal computer or the like. The printer103is a color printer, for example, in a so-called tandem system. The printer103includes an image forming device30, a conveying device40, a fuser50, and paper ejection rollers60.

The image forming device30forms the images on the sheet P by using toner having a color of yellow (Y), magenta (M), cyan (C), or black (K). The image forming device30includes an exposure unit31, imaging units32, and a transfer unit33.

The exposure unit31generates light31afor exposing a photoreceptor drum32A (hereinafter referred to as exposing light31a). The exposing light31aforms an electrostatic latent image corresponding to the image of the above-described each color on the photoreceptor drum32A included in each of four imaging units32described later. As the exposure unit31, an exposure unit that scans the photoreceptor drum32A by using laser light from a semiconductor laser device may be used. As the exposure unit31, an exposure unit including a solid scanning device such as an LED instead of the semiconductor laser device.

Each of the four imaging units32includes one image carrying body, i.e., the photoreceptor drum32A. The respective photoreceptor drums32A are separated each other from the left side to the right side and arranged in parallel inFIG. 1. Each photoreceptor drum32A is rotary driven clockwise as shown by using a drive motor (not shown). Each imaging unit32includes a charger32B, a developing unit32C, and a photoreceptor cleaner32E at each outer periphery of the photoreceptor drum32A. The charger32B, the developing unit32C, and the photoreceptor cleaner32E are arranged in this order in a rotational direction of each photoreceptor drum32A. The imaging units32are arranged upward the exposure unit31. On the four photoreceptor drums32A, the electrostatic latent images corresponding to the respective colors of Y, M, C, and K from the left side to the right side are formed. Thereafter, toner images corresponding to the electrostatic latent images are formed. Each charger32B, each developing unit32C, and each photoreceptor cleaner32E in each imaging unit32have the same configuration except that the color of the toner used for imaging is different.

The charger32B uniformly charges the surface of the photoreceptor drum32A. The exposure unit31irradiates the exposing light31amodulated on the basis of the image data onto the charged photoreceptor drum32A. On the photoreceptor drum32A, the electrostatic latent image is formed.

Each developing unit32C includes a developing roller. The developing unit32C charges the toner therein. A developing bias is applied to the developing roller. The developing unit32C feeds the charged toner to the surface of the photoreceptor drum32A using the developing roller. Once the toner is fed to the surface of the photoreceptor drum32A, the electrostatic latent image on the photoreceptor drum32A is developed with the toner. Each toner cartridge32F is arranged upward each developing unit32C via each transfer unit33described later. According to this embodiment, four toner cartridges32F feeding toner having respective colors of Y, M, C, and K are arranged. Between each toner cartridge32F and each developing unit32C, a toner dispenser (not shown) is arranged. The toner in each toner cartridge32F is fed to each developing unit32C by the toner dispenser.

Each photoreceptor cleaner32E removes the toner not primary transferred by a transfer unit33described later and remained on the photoreceptor drum32A from the surface of the photoreceptor drum32A. For example, the photoreceptor cleaner32E has a cleaning blade that comes in contact with the photoreceptor drum32A. The cleaning blade removes the toner remained on the surface of the photoreceptor drum32A.

The transfer unit33is arranged upward each photoreceptor drum32A facing to each photoreceptor drum32A. The transfer unit33sequentially transfers each toner image formed on the surface of each photoreceptor drum32A to an intermediate transfer belt33A described later (primary transfer). By the primary transfer, the toner image of each color (primary transferred image) is formed on the intermediate transfer belt33A. Furthermore, transfer unit33transfers the primary transferred image on the sheet P (secondary transfer). By the secondary transfer, the toner image is formed on the sheet P. The transfer unit33includes the intermediate transfer belt33A, a drive roller33B, an idler roller33C, a primary transfer roller33D, a secondary transfer roller33E, and an intermediate transfer belt cleaner33F.

The intermediate transfer belt33A is horizontally stretched in the left and right directions by the drive roller33B and a plurality of idler rollers33C inFIG. 1. The drive roller33B is rotary driven counterclockwise as shown by using a drive motor (not shown). When the drive roller33B is driven, the intermediate transfer belt33A endlessly travels counterclockwise as shown. A linear speed of the intermediate transfer belt33A is controlled corresponding to a speed (process speed) of forming the toner image on the photoreceptor drum32A. The process speed is set in advance. The lower surface of the intermediate transfer belt33A shown is in contact with the upper surface of each photoreceptor drum32A.

Inside the intermediate transfer belt33A, each primary transfer roller33D is arranged at the position facing to each photoreceptor drum32A. When a voltage for the primary transfer is applied, the primary transfer roller33D performs the primary transfer of the toner image on each photoreceptor drum32A to the intermediate transfer belt33A.

The secondary transfer roller33E is arranged facing to the drive roller33B via the intermediate transfer belt33A. The contact position between the secondary transfer roller33E and the intermediate transfer belt33A is a secondary transfer position where the toner image is transferred (secondary transfer) from the intermediate transfer belt33A to the sheet P. A secondary transfer voltage is applied to the secondary transfer roller33E at the secondary transfer position, when the sheet P passes between the drive roller33B and the secondary transfer roller33E. When the secondary transfer voltage is applied, the secondary transfer roller33E performs the secondary transfer of the toner image of the intermediate transfer belt33A on the sheet P.

At the position near the idler roller33C shown at the left end of the drawing, an intermediate transfer belt cleaner33F is arranged. The intermediate transfer belt cleaner33F removes the toner that is not secondary transferred to the sheet P and remained on the intermediate transfer belt33A from the intermediate transfer belt33A. For example, the intermediate transfer belt cleaner33F includes a cleaning blade being in contact with the intermediate transfer belt33A. The cleaning blade removes the toner remained on the surface of the intermediate transfer belt33A.

The conveying device40conveys the sheet P fed from the paper feeding cassette104ain the first conveying direction (direction from the lower side to the upper side as shown) along a first conveying path41of the printer103. The first conveying path41includes a plurality of conveying guide members. The first conveying path41guides conveyance of the sheet P. The first conveying path41is arranged between the position of the paper feed roller104band the above-described secondary transfer positon, between the secondary transfer position and a position of the fuser50described later, and between the position of the fuser50and positions of the paper ejection rollers60described later.

The conveying device40further includes an aligning mechanism42. The aligning mechanism42is arranged at the first conveying path41between the position of the paper feed roller104band the secondary transfer position. The aligning mechanism42includes at least one adjustment roller driven by a drive motor (not shown). The adjustment roller corrects the course of the sheet P on the basis of detection outputs of sheet conveying sensors47described later. The adjustment roller aligns the edge position of the sheet P. In a case where the aligning mechanism42includes a plurality of adjustment rollers, the adjustment rollers may include course correcting rollers (first and second course correcting rollers46A and46B) and resist roller45s.The course correcting rollers (first and second course correcting rollers46A and46B) correct the course of the sheet P on the basis of the detection outputs of the sheet conveying sensors47described later. The resist rollers45align the edge position of the sheet P. In a case where the adjustment roller of the aligning mechanism42is rotary-driven by the drive motor (not shown), the adjustment roller conveys the sheet P in the first conveying direction. A linear speed of the adjustment roller is controlled so as to synchronize with the linear speed of the intermediate transfer belt33A. In other words, the linear speed of the adjustment roller is controlled such that the toner image formed on the intermediate transfer belt33A and the edge of the sheet P are synchronized with and arrive at the secondary transfer position. Note that a detailed configuration of the aligning mechanism42will be described after an overall configuration of the image forming system100is described.

The fuser50fuses the toner image transferred to the sheet P passing through the secondary transfer position on the sheet P. The fuser50is arranged upward the secondary transfer roller33E. The fuser50includes a fusing member51and a pressing member52. The fusing member51and the pressing member52come in contact with each other to form a nip (fusing nip). The fusing member51and the pressing member52nips the sheet P conveyed through the first conveying path41at the fusing nip. The fusing member51heats the sheet P at the fusing nip. As the fusing member51, a tube-shaped endless belt or roller is used. A heating source of the fusing member51is not especially limited as long as the surface temperature of the fusing member51can be controlled at a fusing temperature. The pressing member52presses the sheet P at the fusing nip. As the pressing member52, the tube-shaped endless belt or roller is used, for example.

At least one of the fusing member51and the pressing member52is rotary-driven by a drive motor (not shown). When the drive motor is rotated, the sheet P nipped between the fusing member51and the pressing member52is conveyed in the first conveying direction at the fusing speed corresponding to the process speed.

The paper ejection rollers60are arranged at the end of the first conveying path41upward the fuser50. Upward the fuser50, the first conveying path41is curved from the right side to the left side as the first conveying path41directs from the lower side to the upper side as shown. A paper ejection plate103ais arranged at the left side of the paper ejection rollers60as shown, upward the image forming device30, and downward the scanner101.

The paper ejection rollers60are rotary-driven in a forward and reverse ratable manner by a drive motor (not shown). When the paper ejection rollers60rotate forward, the paper ejection rollers60convey the sheet P conveyed through the first conveying path41further to the paper ejection plate103a.While the paper ejection rollers60continue to rotate forward, the sheet P is ejected on the paper ejection plate103a.The paper ejection rollers60are a pair of rollers, for example. When the paper ejection rollers60rotate reverse while the sheet P enters between the pair of paper ejection rollers60, the sheet P is conveyed from the left side to the right side along a route of the end of the first conveying path41(switch back). In this case, the paper ejection rollers60can convey the sheet P to an inverting device105described later.

The inverting device105inverses the sheet P inside out that is passed through the fuser50and is switch-backed, and feeds the sheet P again to the aligning mechanism42. The inverting device105is used for double-sided printing. The inverting device105is arranged at the position (right side as shown) facing to the image forming device30via the first conveying path41. The inverting device105has a second conveying path71. The second conveying path71includes a plurality of conveying guide members. The second conveying path71guides conveyance of the sheet P. The second conveying path71is branched from the first conveying path at the position between the fuser50and the paper ejection rollers60. At the branched position of the first conveying path41and the second conveying path71, a conveying path switching unit72is arranged. The conveying path switching unit72has a conveying path switching member73that guides the sheet P from the first conveying path41to the second conveying path71upon the reverse rotation of the paper ejection rollers60. The second conveying path71merges with the first conveying path41at a merge position between the paper feeding device104and the aligning mechanism42.

The second conveying path71includes a plurality of inversing conveying rollers driven by a drive motor (not shown). Each inversing conveying roller conveys the sheet P in the second conveying direction. The second conveying direction directs from the paper ejection rollers60to the conveying path switching unit72via the first conveying path41and from the conveying path switching unit72to the merge position74via the second conveying path71. The sheet P conveyed from the merge position74to the first conveying path41is conveyed in the first conveying direction of the first conveying path41.

The manual paper feeding device106feeds the sheets P for image formation set manually as appropriate to the printer103. In the following description, the direction to which the sheets P are moved for feeding the sheets P to printer103by the manual paper feeding device106is referred to as a second paper feeding direction. In the example ofFIG. 1, the second paper feeding direction is the direction from the right side to the left side as shown. In the following description, the direction orthogonal to the second paper feeding direction in the sheet plane of the sheets P is referred to as a second paper feeding orthogonal direction.

The manual paper feeding device106has a manual paper feeding tray106aand manual feeding guides106b.The manual paper feeding tray106ais revolvably arranged making an axis of rotation extending in the second paper feeding orthogonal direction as the center. In a case where the manual paper feeding device106is used, the manual paper feeding tray106ais revolved in the arrow direction as shown (clockwise direction) and is held at the position protruding from a side of a housing of the image forming system100(position shown inFIG. 1). In a case where the manual paper feeding device106is not used, the manual feeding paper feeding tray106ais housed in the side of the housing of the image forming system100at the position overlapping with the inverting device105(position shown by a long dashed double dotted line inFIG. 1). The manual feeding guides106binclude wall-shaped members extending in the second paper feeding direction in parallel with and facing to the second paper feeding orthogonal direction with respect to each other. The manual feeding guides106bare arranged such that each sheet P set on the manual feeding paper feeding tray106ais nipped therebetween in the second paper feeding orthogonal direction. The manual feeding guides106bare slide-movable in the second paper feeding orthogonal direction corresponding to a size of the sheet set on the manual feeding paper feeding tray106a.The manual feeding guide106baligns each sheet P having a certain size on a center basis on the manual feeding paper feeding tray106a.In other words, the sheets P are set on the manual feeding paper feeding tray106aby the manual feeding guide106bsuch that the center axis line of the width of each sheet P in the second paper feeding orthogonal direction is aligned with a fixed position.

The manual paper feeding device106has a roller conveying mechanism43. The roller conveying mechanism43separates the sheets P one by one from the manual feeding paper feeding tray106aand feeds the sheet P to the first conveying path41. The method of feeding the sheets P by the roller conveying mechanism43is not especially limited as long as it is the roller paper feeding method. Similarly, the method of separating the sheets P by the roller conveying mechanism43is also not especially limited. Examples of the method of separating the sheets P include an appropriate separation method such as a separation pad system, a separation roller system, and the like.FIG. 1shows the separation roller system as an example. The roller conveying mechanism43has a variety of rollers, pad members, or the like corresponding to the paper feeding system and the separation system. A detailed configuration of the roller conveying mechanism43will be described after the overall configuration of the image forming system100is described.

The controller110controls actions of each device of the image forming system100on the basis of an operation input from the operation device (not shown). For example, the controller110has a CPU, a read only memory (ROM), a random access memory (RAM), an input-output interface, an input-output control circuit, a paper feeding/conveying control circuit, an image forming control circuit, and a fusing control circuit. The CPU realizes a processing function for image formation by executing a program stored in the ROM or the RAM. The input-output control circuit of the controller110controls the operation device and a display device. As the operation device, an operation panel including a key board, a display, and the like may be used. As the display device, a display displaying an image, character information, and the like may be used. The paper feeding/conveying control circuit drive-controls the paper feeding device104, the inverting device105, the printer103, the paper ejection rollers60, and a variety of drive motors included in the inverting device105. The image forming control circuit controls actions of the ADF102, the scanner101, and the image forming device30on the basis of a control signal from the CPU. The fusing control circuit controls actions of the drive motor of the fuser50and the temperature of the fusing member51on the basis of the control signal from the CPU. A paper feeding control by the controller110will be described later.

The image forming system100includes the sheet conveying apparatuses1,2,3according to this embodiment. The sheet conveying apparatus1according to this embodiment includes the manual paper feeding device106, the aligning mechanism42, the sheet conveying sensors47described later, and the controller110. The sheet conveying apparatus2according to this embodiment includes the paper feeding device104, the aligning mechanism42, the sheet conveying sensors47, and the controller110. The sheet conveying apparatus3according to this embodiment includes the inverting device105, the aligning mechanism42, the sheet conveying sensors47, and the controller110. Hereinafter, a detailed configuration of the sheet conveying apparatus1will be mainly described.

As shown inFIGS. 2 to 4, the roller conveying mechanism of the manual paper feeding device106has a pick-up roller43B, a paper feed roller43A, and a separation roller43C. The pick-up roller43B is arranged upward an edge of the manual feeding paper feeding tray106a.The pick-up roller43B rotates in conjunction with the rotation of the paper feed roller43A described later. The pick-up roller43B includes a one-way clutch inside so as not to rotate in the direction opposite to a rotational direction of the paper feed roller43A. The pick-up roller43B is contactable/separatable to an upper surface of the manual feeding paper feeding tray106aby a third contact/separate mechanism44B (seeFIG. 5AandFIG. 5B) descried later. The pick-up roller43B takes out the sheet P (seeFIG. 2) set on the manual feeding paper feeding tray106a.The pick-up roller43B conveys the taken-out sheet P in the second paper feeding direction toward the paper feed roller43A.

The paper feed roller43A is arranged in line with the pick-up roller43B at the position toward the second paper feeding direction with respect to the pick-up roller43B (e.g., left side inFIG. 3). The paper feed roller43A is fixed to the axis of rotation43b.The axis of rotation43bis revolvably fixed to a body of the printer103by a bearing (not shown). The axis of rotation43bis connected to a paper feed roller drive motor (not shown). The paper feed roller drive motor rotary-drives the axis of rotation43b.A pick-up arm43ais connected to the axis of rotation43b.The pick-up arm43ais revolvable around the center axis line of the axis of rotation43b.The pick-up arm43arotatably supports the pick-up roller43B around the center axis line. As shown inFIG. 4, belt pulleys are provided to the paper feed roller43A and the pick-up roller43B, respectively. A belt43jis turned around the belt pulleys. The pick-up roller43B rotates in conjunction with the paper feed roller43A with the belt43jin the same direction as the paper feed roller43A.

A configuration of the third contact/separate mechanism44B is not especially limited as long as the pick-up roller43B is contactable/separatable to the manual feeding paper feeding tray106aand the sheets P on the manual feeding paper feeding tray106a.In the example shown inFIG. 5A, the third contact/separate mechanism44B has a lever44g,a tension spring44m,and a solenoid44k.

The lever44gis revolvably supported by a revolving shaft44hwith respect to the body of the printer103. The lever44gis extended in different directions from the revolving shaft44h.The lever44ghas a first end44iand a second end44jat edges in the extending direction. To the first end44i,the tension spring44mand the solenoid44kare connected. The second end44jis arranged at a lower side of the locking unit43i.The second end44jis contactable/separatable to the locking unit43iat a lower side of the locking unit43i.The locking unit43iis arranged at the pick-up arm43aor the pick-up roller43B. The tension spring44mpulls the first end44i.The tension direction of the tension spring44mis the direction where the lever44gis revolved counterclockwise as shown by taking the revolving shaft44has the center. The end of the tension spring44mopposite to the end connected to the first end44iis fixed to the body of the printer103. The solenoid44kswitches the state of pulling the first end44iand the state of cancelling the pulling by turning on/off electricity. The solenoid44kpulls the first end44iin the direction opposite to the pulling direction of the tension spring44mwhen electricity is turned on. The solenoid44krevolves the lever44gclockwise as shown by pulling the first end44iagainst the pulling of the tension spring44mwhen electricity is turned on.

FIG. 5Ashows the state that the lever44gis revolved at the maximum clockwise as shown when electricity is turned on to the solenoid44k.In this case, the second end44jis separated downward the locking unit43i.The pick-up arm43ais revolved at the maximum clockwise as shown by own weights of the pick-up arm43aand pick-up roller43B. The pick-up roller43B is in contact with the manual feeding paper feeding tray106aor the sheet P (not shown) on the manual feeding paper feeding tray106afrom the above. In contrast,FIG. 5Bshows the state of the solenoid44kwhen electricity is turned off. When electricity is turned off to the solenoid44k,the lever44gis pulled by the tension spring44m.The lever44gis revolved counterclockwise as shown.FIG. 5Bshows the state that the lever44gis revolved at the maximum counterclockwise as shown. In this case, the second end44jis in contact with a lower end of the locking unit43idownward. The pick-up arm43ais revolved counterclockwise as shown taking the axis of rotation43bas the center. The pick-up roller43B is moved upward the manual feeding paper feeding tray106aor the sheets P (not shown) on the manual feeding paper feeding tray106a.The pick-up roller43B is separated from the manual feeding paper feeding tray106aor the sheets P (not shown) on the manual feeding paper feeding tray106a.

As shown inFIG. 3, the separation roller43C is arranged facing to the paper feed roller43A downward the paper feed roller43A. The separation roller43C is contactably/separatably arranged with respect to the paper feed roller43A and the sheet P (not shown) conveyed by the paper feed roller43A. The separation roller43C is connected to a paper feed roller drive motor (not shown) via a torque limiter43f,an axis of rotation43d,and a transmission mechanism (not shown). Note that a rotary drive direction of the separation roller43C is the same direction as the rotational direction of the paper feed roller43A. The torque limiter43fis arranged so as to perform a separation action that prevents the sheets P from multiple paper feeding.

The torque limiter43fcancels the connection to the paper feed roller drive motor with a torque based on a frictional force received from the paper feed roller43A when the paper feed roller43A comes in contact with the separation roller43C. In this case, the separation roller43C rotates in conjunction with the paper feed roller43A in a reverse direction. The separation roller43C adds a certain torque load to the paper feed roller43A. The torque limiter43fmaintains the connection to the paper feed roller drive motor with the torque based on a frictional force received from the sheet P in a case where the sheet P enters between the paper feed roller43A and the separation roller43C. In this case, the separation roller43C continues to rotate clockwise as shown. The frictional force from the separation roller43C acts on the sheet P in the direction opposite to the second paper feeding direction. The frictional force from the separation roller43C is smaller than a frictional force acted from the paper feed roller43A to the sheet P being in contact with the paper feed roller43A. Note that the frictional force from the separation roller43C is greater than a frictional force between a plurality of sheets P. Accordingly, the separation roller43C slips with respect to one sheet P being in contact with the paper feed roller43A. In a case where a plurality of sheets P enter between the paper feed roller43A and the separation roller43C, the separation roller43C pushes back the sheets P thereunder in the direction opposite to the second paper feeding direction until the number of the sheets P between the paper feed roller43A and the separation roller43C becomes one. By performing the separation action, the separation roller43C prevents the sheets P from multiple paper feeding.

As shown inFIG. 5AandFIG. 5B, in this embodiment, the axis of rotation43dof the separation roller43C is rotatably supported by a bearing43efixed to a revolving arm43h.The revolving arm43his revolvably fixed to a support shaft43garranged by a support shaft43garranged at the right side of the separation roller43C. The support shaft43gextends in parallel with the axis of rotation43b.The support shaft43gis fixed to the body of the printer103. The revolving arm43his revolved around the support shaft43gby a second contact/separate mechanism44A described later. With this configuration, the separation roller43C is contactably/separatably supported on the paper feed roller43A. The above-described separation action is performed in a case where the separation roller43C is in contact with the paper feed roller43A or in a case where the separation roller43C is in contact with the sheet P conveyed by the paper feed roller43A.

The second contact/separate mechanism44A is not especially limited as long as the separation roller43C can be contacted/separated with respect to the sheet P conveyed by the paper feed roller43A and the paper feed roller43A. In the example shown inFIG. 5A, the second contact/separate mechanism44A has the configuration substantially similar to that of the third contact/separate mechanism44B. The second contact/separate mechanism44A has a lever44a,a tension spring44f,and a solenoid44e.

The lever44ais revolvably supported by a revolving shaft44bwith respect to the body of the printer103. The lever44ais extended in different directions from the revolving shaft44b.The lever44dhas a first end44cand a second end44dat edges in the extending direction. To the first end44c,the tension spring44fand the solenoid44eare connected. The second end44dis arranged at a lower side of the bearing43e.The second end44dis contactable/separatable to the bearing43eat a lower side of the bearing43e.The tension spring44fpulls the first end44c.The tension direction of the tension spring44fis the direction where the lever44ais revolved clockwise as shown by taking the revolving shaft44bas the center. The end of the tension spring44fopposite to the end connected to the first end44cis fixed to the body of the printer103. The solenoid44eswitches the state of pulling the first end44cand the state of cancelling the pulling by turning on/off electricity. The solenoid44epulls the first end44cin the direction opposite to the pulling direction of the tension spring44fwhen electricity is turned on. The solenoid44erevolves the lever44acounterclockwise as shown by pulling the first end44cagainst the pulling of the tension spring44fwhen electricity is turned on.

FIG. 5Ashows the state that the lever44ais revolved at the maximum clockwise as shown when electricity is turned off to the solenoid44e.In this case, the lever44ais pulled by the tension spring44f.The second end44dpresses the bearing43efrom downward to upward. The revolving arm43his revolved at the maximum clockwise as shown. The separation roller43C is in contact with the paper feed roller43A or the sheet P (not shown) fed by the paper feed roller43A from the lower side. In contrast,FIG. 5Bshows the state of the solenoid44ewhen electricity is turned on. When electricity is turned on to the solenoid44e,the lever44ais pulled by the solenoid44ein the direction opposite to the pulling direction of the tension spring44f.The lever44ais revolved counterclockwise as shown.FIG. 5Bshows the state that the lever44gis revolved at the maximum counterclockwise as shown. In this case, the second end44dis in contact with the bearing43efallen down by own weights of the revolving arm43hand the separation roller43C. The revolving arm43his revolved counterclockwise as shown taking the axis of rotation43gas the center. The separation roller43C is moved downward the paper feed roller43A or the sheet P (not shown) fed by the paper feed roller43A. The separation roller43C is separated from the paper feed roller43A or the sheet P (not shown) fed by the paper feed roller43A.

As shown inFIG. 3, the aligning mechanism42has the resist rollers45(adjustment roller), pre-resist detection sensor45s,and the course correcting unit46. The resist rollers45include a first roller45a(adjustment roller) and a second roller45b(adjustment roller). The first roller45aand the second roller45bcome in contact with each other to form a nip. For example, as the first roller45a,a metal roller may be used. For example, as the second roller45b,a rubber roller may be used. The first roller45aand the second roller45bare driven by a resist roller drive motor (not shown). The resist rollers45align the edge of the sheet P. After the edge of the sheet P is aligned, the resist rollers45convey the sheet P through the first conveying path41to the secondary transfer position.

As shown inFIG. 3, the pre-resist detection sensor45sis arranged at the first conveying path41between the resist rollers45and the course correcting unit46described later. The pre-resist detection sensor45sdetects whether or not the edge of the sheet P arrives at a detection position. A length from a detection position of the pre-resist detection sensor45sin the first conveying direction to positions of the resist rollers45is stored in the controller110in advance.

The course correcting unit46is arranged at the first conveying path41between the merge position74and the aligning mechanism42. As shown inFIG. 6AandFIG. 6B, the course correcting unit46has a holder46a,flanges46hand46s,a motor for parallel movement Mp, a drive plate46m,a motor for revolving Mr, first course correcting rollers46A (adjustment roller and course correcting roller), and second course correcting rollers46B (adjustment roller and course correcting roller).

The holder46aholds the first course correcting rollers46A and the second course correcting rollers46B described later. The holder46acan move the first course correcting rollers46A and the second course correcting rollers46B together. As shown inFIG. 6A, the holder46ais moved in parallel with a conveying surface of the sheet P by the motor for parallel movement Mp described later. Specifically, the holder46ais moved in a parallel movement direction Dp along a first conveying orthogonal direction D2orthogonal to a first conveying direction D1in the conveying surface of the sheet P. The holder46arotates and moves in a revolving direction Dr in the conveying surface of the sheet P by the motor for revolving Mr described later. As shown inFIG. 6B, both ends of the holder46a,respective side plates46dare mounted upright. A bearing46bis fixed to each side plate46d.The bearing46brotatably supports the first course correcting rollers46A around the center axis line. In each side plate46d,a long slide hole46epenetrates in the direction facing to the bearing46bnext to the bearing46b.

Flanges46hand46sare arranged at a base end (upper end inFIG. 6B) of each side plate46d.The flanges46hand46sextend from the both ends of the holder46ain the longitudinal direction to downward. A flange46hhas a slide hole46iand a rack46j.As shown inFIG. 6A, the slide hole46ipenetrates in the thickness direction of the flange46h.The slide hole46iis long in the longitudinal direction of the holder46a.A guide pin46kfixed to the body of the printer103is inserted into the slide hole46i.The rack46jis formed in an extension direction in a side facing to the extension direction of the flange46h.A drive force of the motor for parallel movement Mp is transmitted to the rack46jvia a transmission mechanism Gp. For example, as the transmission mechanism Gp, a gear wheel transmission mechanism having a pinion of driving the rack46jmay be used. To the body of the printer103, a first HP detection sensor H1is fixed. The first HP detection sensor H1detects a home position (HP) of the flange46hin the parallel movement direction Dp. For example, as the first HP detection sensor H1, a photo interpreter may be used.

As shown inFIG. 6AandFIG. 6B, the flange46shas a slide hole46r.The slide hole46rpenetrates in the thickness direction of the flange46s.The slide hole46ris long in the longitudinal direction of the holder46a.The drive plate46mis revolvably arranged in a plane parallel to the conveying surface of the sheet P taking the rotation shaft46nas the center. A drive pin46qis mounted upright to an upper surface of the drive plate46m.The drive pin46qpenetrates through the slide hole46rof the flange46sdownward. As shown inFIG. 6A, the flange46sreceives the drive force from the drive pin46qwhen the drive plate46mis revolved around the rotation shaft46nas the center. Corresponding to an amount of movement of the drive pin46q,the flange46sis revolved in the revolving direction Dr. At this time, the guide pin46kis inserted into the slide hole46i.Accordingly, the holder46ais revolved in the revolving direction Dr as a whole around the guide pin46kas the center. At an outer periphery of the drive plate46m,a gear46pis formed.

The drive force of the motor for revolving Mr is transmitted to the gear46pvia the transmission mechanism Gr. For example, as the transmission mechanism Gr, a gear wheel transmission mechanism may be used. A second HP detection sensor H2is fixed to the body of the printer103. The second HP detection sensor H2detects the HP of the flange46sin the revolving direction Dr. For example, as the second HP detection sensor H2, the photo interpreter may be used. In this embodiment, the HP of the holder46ais the position when the first course correcting rollers46A and the second course correcting rollers46B extend in the first conveying orthogonal direction D2and the first course correcting rollers46A and the second course correcting rollers46B are positioned at the center of the first conveying path41in the first conveying orthogonal direction D2, as described later. Hereinafter, unless otherwise specified, a positional relationship among respective members of the course correcting unit46is described in a case where the holder46ais in the HP as an example.

The first course correcting rollers46A are fixed to the axis of rotation46f.Both ends of the axis of rotation46fare inserted into the bearing46bfixed to each side plate46d.The axis of rotation46fextends in the longitudinal direction of the holder46a.As shown inFIG. 6B, an end of the axis of rotation46f(end at right side shown) penetrating to the side plate46dhaving the flange46his connected to the transmission mechanism Gd via a joint46t.The transmission mechanism Gd transmits the drive force from a course correcting roller drive motor (not shown) to the axis of rotation46f.For example, as the transmission mechanism Gd, a gear wheel transmission mechanism may be used. The joint46tis expandable, contractable, and revolvable along with the movement of the axis of rotation46fif the axis of rotation46fmoves in association with a parallel movement and a revolving movement of the holder46a.A drive gear46uis fixed to the axis of rotation46fbetween the joint46tand the side plate46d.The drive gear46utransmits the drive force from the course correcting roller drive motor to the second course correcting rollers46B.

The second course correcting rollers46B are fixed to the axis of rotation46g.Both ends of the axis of rotation46gare inserted into the bearing46c.The bearing46cis, for example, a stepped slide bearing. As shown inFIG. 7A, a small diameter part46wof the bearing46cis slidably fitted to the slide hole46ein the longitudinal direction. A large diameter part46xof the bearing46cis slidably locked to an outer surface of the side plate46d.An idler gear46vis fixed to the end (end at right side shown) of the axis of rotation46gpenetrating through the side plate46dat the side where the flange46his arranged. The number of teeth of the idler gear46vequals to the number of teeth of the drive gear46u.The idler gear46vis engaged with the drive gear46uin a case where a positional relationship is such that the second course correcting rollers46B come in contact with the first course correcting rollers46A each other. When the idler gear46vis engaged with the drive gear46u,the second course correcting rollers46B will be rotatable in the reverse direction of the first course correcting rollers46A.

The course correcting unit46further includes a first contact/separate mechanism48. The first contact/separate mechanism48allows the second course correcting rollers46B to be in contact with/be separated from the first course correcting rollers46A. The first contact/separate mechanism48is not especially limited as long as the second course correcting rollers46B are contactable/separatable to the first course correcting rollers46A. In the example shown inFIG. 7A, the first contact/separate mechanism48has a lever48a,a tension spring48f,and a solenoid48e.

The lever48ais revolvably supported by a revolving shaft48bwith respect to the holder46a.The lever48ais extended in different directions from the revolving shaft48b.The lever48ahas a first end48cand a second end48dat edges in the extending direction. To the first end48c,the tension spring48fand the solenoid48eare connected. The second end48dis arranged at a lower side of the large diameter part46xof the bearing46c.The second end48dis contactable/separatable to the large diameter part46x.The tension spring48fpulls the first end48c.The tension direction of the tension spring48fis the direction where the lever48ais revolved counterclockwise as shown by taking the revolving shaft48bas the center. The end of the tension spring48fopposite to the end connected to the first end48cis fixed to a fixing unit (not shown) extending from the holder46a.The solenoid48eswitches the state of pulling the first end48cand the state of cancelling the pulling by turning on/off electricity. The solenoid48epulls the first end48cin the direction opposite to the pulling direction of the tension spring48fwhen electricity is turned on. The solenoid48erevolves the lever48acounterclockwise as shown by pulling the first end48cagainst the pulling direction of the tension spring48fwhen electricity is turned on.

FIG. 7Ashows the state that electricity is turned off to the solenoid48e.When electricity is turned off to the solenoid48e,the lever48ais pulled by the tension spring48f.The lever48ais revolved clockwise as shown.FIG. 7Ashows the state that the lever48ais revolved at the maximum clockwise as shown. In this case, the second end48dpresses the large diameter part46xof the bearing46cfrom downward to upward. At this time, as shown inFIG. 6B, the first course correcting rollers46A and the second course correcting rollers46B are in contact with each other. The drive gear46uand the idler gear46vare engaged with each other on their pitch circles. In contrast,FIG. 7Bshows the state of the solenoid48ewhen electricity is turned on. When electricity is turned on to the solenoid48e,the lever48ais pulled by the solenoid48ein the direction opposite to the pulling direction of the tension spring48f.The lever48ais revolved counterclockwise as shown. In this case, the second end48dis in contact with the large diameter part46xof the bearing46cfallen down by own weights of the second course correcting rollers46B. At this time, the second course correcting rollers46B are separated from the first course correcting rollers46A (see the long dashed double dotted line inFIG. 3).

The sheet conveying sensors47detect the course of the sheet P conveyed toward the resist roller45. The course of the sheet P is represented by an amount of skew deviation with respect to a predetermined normal course and an amount of horizontal deviation. The sheet P1shown by the long dashed double dotted line inFIG. 6Ais a first size sheet P that moves in the normal course. Similarly, the sheet P2is a second size sheet P that moves in the normal course. Edges F of the sheets P1and P2extend in the first conveying orthogonal direction D2. A first side end SL and a second side end SR of the sheets P1and P2extend in the first conveying direction Dl. Here, the first side end SL is the side end positioned at a front side of the image forming system100. The second side end SR is the side end positioned at a back side of the image forming system100. The center axis lines of the sheets P1and P2in the first conveying orthogonal direction D2are coincide with the center axis line C of the normal course.

The skew deviation is represented by an angle of the edge of the sheet P in the conveying direction tilted with respect to the axis line extending in the first conveying orthogonal direction. The horizontal deviation is represented by an amount of deviation between the center axis line in the standard course and a rotation center of the skew in the first conveying orthogonal direction D2since the image forming system100conveys the sheet P on a center basis. Note that it is not easy to determine the rotation center during conveyance of the sheet P. In this embodiment, the amount of horizontal deviation is detected on the basis of the position of the side end of the sheet P after the skew deviation is corrected, as described later.

As shown inFIG. 3, in this embodiment, as the sheet conveying sensors47, a skew detection sensor47A and a horizontal deviation detection sensor47B are arranged in the first conveying path41. Furthermore, as the sheet conveying sensors47, a skew detection sensor47C and a horizontal deviation detection sensor47D are arranged in the second conveying path71. The skew detection sensor47A and the horizontal deviation detection sensor47B detect the course of the sheet P (not shown) toward the course correcting unit46from the inverting device105through the merge position74. The detection action by the skew detection sensor47A and the horizontal deviation detection sensor47B and the detection action by the skew detection sensor47C and the horizontal deviation detection sensor47D are similar with respect to each other. Hereinbelow, the skew detection sensor47A and the horizontal deviation detection sensor47B are taken as an example and described.

The skew detection sensor47A has a first skew detection sensor47aand a second skew detection sensor47b.The first skew detection sensor47aand second skew detection sensor47bare arranged at a certain distance from the nips between the first course correcting rollers46A and the second course correcting rollers46B in the first conveying direction D1at the HP of the holder46a.The first skew detection sensor47aand the second skew detection sensor47bare arranged to leave a space with respect to each other on the axis line extending in the first conveying orthogonal direction D2. The first skew detection sensor47aand the second skew detection sensor47bare arranged in line symmetry with respect to each other by the center axis line C. A distance between the first skew detection sensor47aand the second skew detection sensor47bis smaller than a minimum width of the sheet P to be fed.

If there are a plurality of width sizes of the sheets P fed in the first conveying orthogonal direction D2, it is desirable that the horizontal deviation detection sensor47B have a pair of sensors for each width size. Note that a plurality kinds of the sheets P having similar sizes may be detected by a common pair of sensors. In a case where the sheets P to be fed have only one determined width size, the horizontal deviation detection sensor47B may have only one sensor.FIG. 6Ashows an example that the horizontal deviation detection sensor47B has first horizontal deviation detection sensors47cand47eand second horizontal deviation detection sensors47dand47f.The first horizontal deviation detection sensors47cand47eand the second horizontal deviation detection sensors47dand47fare arranged apart from the skew detection sensor47A in the direction opposite to the first conveying direction D1and on the axis line extending in the first conveying orthogonal direction D2. The first horizontal deviation detection sensors47cand47eare arranged at positions corresponding to respective first side ends SL to the sheets P1and P2moving the standard courses, respectively. The second horizontal deviation detection sensors47dand47fare arranged at positions corresponding to respective second side ends SR to the sheets P1and P2moving the standard courses, respectively.

The skew detection sensor47A is not especially limited as long as arrival of the edge F of the sheet P on sensor arrangement positions is detectable. Examples of the skew detection sensor47A include a reflection type or transmission type photo sensor, a line sensor, a CCD, and the like. The horizontal deviation detection sensor47B is not especially limited as long as arrival of the first side end SL or the second side end SR of the sheet P on sensor arrangement positions is detectable. Examples of the horizontal deviation detection sensor47B may include the sensors similar to those used in the skew detection sensor47A.

Here, a relationship between the components of the sheet conveying apparatus1described above and the controller110will be described.FIG. 8is a block diagram showing a configuration example of a control system of the sheet conveying apparatus according to the embodiment.

As shown inFIG. 8, the controller110includes a system controller111, a conveying controller112, and a storage device113. The system controller111controls overall actions of the image forming system100. The system controller111is connected to and communicable with a display device114, an operation device115, the ADF102, the scanner101, the image forming device30, the fuser50, a conveying controller112described later, and the storage device113.

The conveying controller112is connected to and communicable with the system controller111and the storage device113. The conveying controller112controls the actions of the paper feeding device104, the manual paper feeding device106, the roller conveying mechanism43, the inverting device105, and the aligning mechanism42described above on the basis of a control signal from the system controller111. The conveying controller112is further connected to and communicable with the skew detection sensor47A, the horizontal deviation detection sensor47B, a first HP detection sensor H1, a second HP detection sensor H2, the pre-resist detection sensor45s,the motor for parallel movement Mp, the motor for revolving Mr, the first contact/separate mechanism48, the second contact/separate mechanism44A, the third contact/separate mechanism44B, the course correcting roller drive motor M46, the resist roller drive motor M45, and a paper feed roller drive motor M43. Here, the course correcting roller drive motor M46drives the first course correcting rollers46A. The resist roller drive motor M45drives the resist roller45. The paper feed roller drive motor M43supplies a drive force to the roller conveying mechanism43. The paper feed roller drive motor M43drives at least the paper feed roller43A.

The storage device113stores control data needed for the control performed by the system controller111and the conveying controller112. The storage device113includes a ROM, a RAM, other storage medium, or the like.

Next, the actions of the image forming system100will be described mainly about the actions of the sheet conveying apparatus1.FIG. 9is a flowchart showing the actions of the sheet conveying apparatus according to the embodiment.FIGS. 10 to 13are views for describing the actions of the sheet conveying apparatus according to the embodiment.

The image forming system100according to the embodiment shown inFIG. 1performs image formation on the sheets P by an operation of an operator on the operation device or operation commands from an external device connected to the image forming system100. When the sheet P is conveyed from the sheet conveying apparatuses1,2, and3, the toner image is formed on the sheet P by a well-known electrophotographic process performed by the image forming device30. The toner image of the sheet P is fused to the sheet P by the fuser50. The sheet P to which the toner image is fused is ejected to the paper ejection plate103aby the paper ejection rollers60or is conveyed to the inverting device105for performing the image formation on both sides of the sheet P (double-sided printing). Hereinafter, a conveying action of the sheets P performed by the sheet conveying apparatus1will be described in detail.

For example, when a start operation of the image formation is done from the operation device115, the system controller111transmits a control signal of starting paper feeding to the conveying controller112. For example, the paper feeding from the manual paper feeding device106is selected by an operation input from the operation device115. In this case, the conveying controller112feeds and conveys the sheets P to the printer103by executing processes of ACT1to ACT12shown inFIG. 9. In the following description, the width size of the sheet P is the same as that of the sheet P1described above. Before the paper feeding is started by the control of the conveying controller112, electricity is turned off to the solenoid48eof the first contact/separate mechanism48, the solenoid44eof the second contact/separate mechanism44A, and the solenoid44kof the third contact/separate mechanism44B. The holder46aof the course correcting unit46is positioned at the HP.

In ACT1, the roller conveying mechanism43feeds the sheets P. By the conveying controller112, electricity is turned on to the solenoid44kof the third contact/separate mechanism44B. As shown inFIG. 3, the pick-up roller43B comes in contact with the upper surface of the sheet P set on the manual paper feeding device106. The separation roller43C is in contact with the paper feed roller43A. The conveying controller112rotates the paper feed roller drive motor M43. The paper feed roller43A and the pick-up roller43B rotates clockwise as shown. The separation roller43C rotates counterclockwise inFIG. 3by the drive force from the paper feed roller43A. The sheet P is taken out from the manual feeding paper feeding tray106aby the pick-up roller43B. The sheet P is conveyed in the second paper feeding direction by the pick-up roller43B. The edge of the sheet P arrives at the nip between the paper feed roller43A and the separation roller43C. Even if a plurality of sheets P are conveyed from the manual feeding paper feeding tray106a,the above-described separation action is performed by the separation roller43C. Accordingly, one sheet P enters into the nip between the paper feed roller43A and the separation roller43C. The sheet P is conveyed in the first conveying path41that directs to the course correcting unit46by receiving the drive force from the paper feed roller43A. In this manner, the process of ACT1is ended.

After the process of ACT1, a process of ACT2is performed. In ACT2, the skew detection sensor47A detects skew of the sheet P. For example, after the process of ACT1, when the sheet P moves in the standard course, as schematically shown as the P1inFIG. 10, a nip N45of the paper feed roller43A and the separation roller43C, a nip N46of the first course correcting rollers46A and the second course correcting rollers46B, and the edge F are all parallel to the axis line extending in the first conveying orthogonal direction D2. However, due to a various reasons, the sheet P may not move in the standard course. For example, as shown inFIG. 11, the sheet P may move by tilting at angle θ with respect to the center axis line C of the standard course. The edge F of the sheet P is skewed with respect to the nip N45by the angle θ. Furthermore, the course of the sheet P1is horizontally deviated with respect to the center axis line C.

The skew of the sheet P is detected by the first skew detection sensor47aand the second skew detection sensor47bof the skew detection sensor47A. In the example shown inFIG. 11, the edge F of the sheet P passes through the detection position of the second skew detection sensor47bat time t1and then passes through the detection position of the first skew detection sensor47aat time t2. The second skew detection sensor47band the first skew detection sensor47atransmit detection signals that detect the passage of the edge F to the conveying controller112at respective detection times. The conveying controller112receives the detection signals from both of the second skew detection sensor47band the first skew detection sensor47aand then calculates the angle θ that represents the skew deviation of the edge F on the basis of a time difference between time t2and time t1, the linear speed of the paper feed roller43A. In this manner, the process of ACT2is ended.

After the process of ACT2, a process of ACT3is performed. In ACT3, corresponding to the skew of the sheet P, the first course correcting rollers46A and the second course correcting rollers46B revolve. The conveying controller112revolves the holder46asuch that the nip N46will be in parallel with the edge F. Specifically, the conveying controller112calculates an amount of rotation of the motor for revolving Mr with respect to the angle θ. The conveying controller112rotates the motor for revolving Mr on the basis of the amount of rotation calculated. The holder46aholding the first course correcting rollers46A and the second course correcting rollers46B is revolved by the angle θ taking the guide pin46kas the revolving center. In this manner, as shown inFIG. 11, the nip N46is arranged in parallel with the edge F. In this manner, the process of ACT3is ended.

After the process of ACT3, a process of ACT4is performed. In ACT4, the edge F of the sheet P enters to the nip N46of the first course correcting rollers46A and the second course correcting rollers46B (seeFIG. 12). In this embodiment, the conveying controller112calculates in advance an estimated arrival time t3that the edge F arrives at the nip N46with certainty on the basis of the time t2when the edge F arrives at the first skew detection sensor47aand the linear speed of the paper feed roller43A until the sheet P arrives at the nip N46. For example, as the distance between the roller conveying mechanism43and the course correcting unit46is long, revolving the holder46ais ended with certainty until the estimated arrival time t3. In this case, the conveying controller112may rotate the course correcting roller drive motor M46at the same time as the start of the paper feeding in ACT1. For example, as the distance between the roller conveying mechanism43and the course correcting unit46is short, revolving the holder46amay not be ended with certainty until the estimated arrival time t3. In this case, the conveying controller112may rotate the course correcting roller drive motor M46after revolving the holder46ais ended. For example, the conveying controller112may rotate the course correcting roller drive motor M46after the end of revolving the holder46aand after the estimated arrival time t3. In this case, the position of the edge F of the sheet P is aligned by the first course correcting rollers46A and the second course correcting rollers46B where their rotation is stopped.

In a case where the course correcting roller drive motor M46is rotated, the sheet P arrived at the nip N46enters to the nip N46by the rotations of the first course correcting rollers46A and the second course correcting rollers46B. The sheet P is nipped with the first course correcting rollers46A and the second course correcting rollers46B. The sheet P is conveyed in the first conveying direction D1by the rotations of the first course correcting rollers46A and the second course correcting rollers46B. In this manner, the process of ACT4is ended.

After the process of ACT4, a process of ACT5is performed. In ACT5, the second contact/separate mechanism44A cancels the pressing of the paper feed roller43A to the sheet P. Specifically, after the estimated arrival time t3and in a case where the course correcting unit46is driven, the conveying controller112controls such that electricity is turned off to the solenoid44eof the second contact/separate mechanism44A and the solenoid44kof the third contact/separate mechanism44B. When electricity is turned off to the solenoid44e,the separation roller43C is separated downward from the sheet P conveyed by the paper feed roller43A. The second contact/separate mechanism44A gives the state (fourth state) that the sheet P is not pressed by the paper feed roller43A. InFIG. 12, the paper feed roller43A is shown by a long dashed double dotted line, which schematically shows that the paper feed roller43A becomes in the fourth state. In other words, the second contact/separate mechanism44A cancels the state (third state) that the sheet P is pressed by the paper feed roller43A. When electricity is turned off to the solenoid44k,the separation roller43B is separated upward from the surface of the sheet P. The state that the pick-up roller43B presses the sheet P is canceled. In this manner, the sheet P is conveyed by the rotations of the first course correcting rollers46A and the second course correcting rollers46B. At this time, a conveyance load of the sheet P caused by the paper feed roller43A, the pick-up roller43B, and the separation roller43C is canceled. In particular, since the sheet P is separated from the separation roller43C, the sheet P will not receive the drive force that returns the sheet P in the direction opposite to the first conveying direction D1and the reverse direction due to the rotation of the separation roller43C. Furthermore, the sheet P will not be restricted by the paper feed roller43A, the pick-up roller43B, and the separation roller43C that do not press the sheet P. The sheet P is conveyed in the direction orthogonal to the nip N46. In this manner, the process of ACT5is ended.

After the process of ACT5, a process of ACT6is performed. In ACT6, the first course correcting rollers46A and the second course correcting rollers46B are revolved together with the holder46a,whereby the skew of the sheet P is corrected. Specifically, the conveying controller112drives the motor for revolving Mr and returns the holder46ato the HP. The nip N46is revolved as shown by an arrow R46inFIG. 12. The revolving angle of the nip N46is −θ. At this time, the sheet P is not pressed by the paper feed roller43A, the pick-up roller43B, and the separation roller43C. The sheet P is revolved similar to the nip N46as shown by arrow RP. The sheet P is not restricted except by the first course correcting rollers46A and the second course correcting rollers46B. The sheet P is smoothly revolved. No warp, corrugation, or the like is generated on the sheet P. As shown inFIG. 13, the edge F of the sheet P′ is in parallel with the nip N45. The skew of the sheet P is corrected. At this time, the position of the edge F in the first conveying direction D1is calculated from the time required to revolve and an amount of conveyance by the first course correcting rollers46A and the second course correcting rollers46B within the time. In this manner, the process of ACT6is ended.

After the process of ACT6is ended, a process of ACT7is performed. In ACT7, the first course correcting rollers46A and the second course correcting rollers46B move in parallel together with the movement holder46a,whereby the horizontal deviation of the sheet P is corrected. Specifically, the conveying controller112monitors the detection signals of the first horizontal deviation detection sensor47cand the second horizontal deviation detection sensor47d.For example, in the example shown inFIG. 12, the first horizontal deviation detection sensor47cdetects that the sheet P (P′) is not present at the detection position of the first horizontal deviation detection sensor47c.The second horizontal deviation detection sensor47ddetects that the sheet P (P′) is present at the detection position of the second horizontal deviation detection sensor47d.On the basis of the combination of the detection signals, the conveying controller112moves in parallel the holder46ain the first conveying orthogonal direction D2closer to the first horizontal deviation detection sensor47cas shown by the arrow S46. Specifically, the conveying controller112drives the motor for parallel movement Mp such that the holder46amoves in the direction shown by the arrow S46. In a case where the first horizontal deviation detection sensor47cand the second horizontal deviation detection sensor47ddetect the first side end SL and the second side end SR of the sheet P, respectively, the conveying controller112stops driving of the motor for parallel movement Mp. By the parallel movement of the holder46a,the sheet P (P′) is moved in parallel in the direction shown by the arrow DP. The arrow DP is a skew direction closer to the center axis line C of the center axis line CP as the edge F of the sheet P (P′) moves in the first conveying direction D1. At this time, the sheet P is not pressed by the paper feed roller43A, the pick-up roller43B, and the separation roller43C. The sheet P is moves in parallel smoothly similar to the revolvement in ACT6. No warp, corrugation, or the like is generated on the sheet P. In this manner, the horizontal deviation of the sheet P is corrected shown as the sheet P″ inFIG. 14. In this manner, the process of ACT7is ended.

For example, the width size of the sheet P is different from an arrangement distance between the first horizontal deviation detection sensor47cand the second horizontal deviation detection sensor47d.In this case, in ACT7, the conveying controller112moves in parallel the sheet P such that the first horizontal deviation detection sensor47cdetects the first side end SL of the sheet P or the second horizontal deviation detection sensor47ddetects the second side end SR of the sheet P. Thereafter, on the basis of the predetermined width size of the sheet P, the sheet P is moved in parallel for a moved distance where the center axis line CP is matched with the center axis line C.

After the process of ACT7is ended, a process of ACT8is performed. In ACT8, it is determined whether or not the edge F of the sheet P arrives at the resist roller45. Specifically, the conveying controller112monitors the detection signal of the pre-resist detection sensor45s.When the detection signal of the pre-resist detection sensor45snotifies the conveying controller112of the arrival of the edge F at a detection position of the first roller45a,the conveying controller112determines that the edge F of the sheet P arrives at the nip N45of the resist rollers45after a predetermined time from a detection time. The predetermined time that is different depending on the conveying speed of the sheet P is stored in the storage device113in advance. In a case where it is determined that the edge F of the sheet arrives at the nip N45of the resist rollers45(ACT8: YES), the process in ACT9is performed. In a case where it is determined that the edge F of the sheet does not arrive at the nip N45of the resist rollers45(ACT8: NO), the process in ACT8is again performed.

After the process of ACT8is ended, a process of ACT9is performed. In ACT9, the second contact/separate mechanism44A causes the paper feed roller43A to press the sheet P. Specifically, by the conveying controller112, electricity is turned off to the solenoid44e.Since the tension spring44fof the second contact/separate mechanism44A revolves the lever44a,the revolving arm43his revolved. The separation roller43C is pressed toward the paper feed roller43A by a tension force of the tension spring44f.The paper feed roller43A presses the sheet P toward the separation roller43C. The sheet P is ready to be conveyed in the first conveying direction D1by the course correcting unit46and the paper feed roller43A. The resist rollers45are stopped. The edge F of the sheet P is pressed toward the nip N45of the resist rollers45. In this manner, the process of ACT9is ended.

After the process of ACT9is ended, a process of ACT10is performed. In ACT10, the first contact/separate mechanism48cancels the pressing of the sheet P to the first course correcting rollers46A and the second course correcting rollers46B. Specifically, by the conveying controller112, electricity is turned on to the solenoid48eof the first contact/separate mechanism48. When electricity is turned on to the solenoid48e,the second course correcting rollers46B are separated from the first course correcting rollers46A by own weights. The first contact/separate mechanism48gives the state (second state) that the sheet P is not pressed by the first course correcting rollers46A and the second course correcting rollers46B. Accordingly, the state (first state) that the sheet P is pressed by the first course correcting rollers46A and the second course correcting rollers46B is canceled. The sheet P is conveyed by the paper feed roller43A in the first conveying direction Dl. Depending on the amount of conveyance, slack is generated between the resist rollers45and the paper feed roller43A. In this manner, the process of ACT10is ended.

After the process of ACT10is ended, a process of ACT11is performed. In ACT11, the conveying controller112monitors whether or not a resist ON signal for starting driving of the resist rollers45is transmitted from the system controller111. The system controller111generates the resist ON signal depending on a state of progress in an imaging process that is performed in parallel with the above-described paper feeding conveying action. The resist ON signal is generated at timing when the toner image on the intermediate transfer belt33A arrives at the secondary transfer position and an effective image area of the sheet P can be arrived at the secondary transfer position. In a case where the resist ON signal is generated (ACT11: YES), a process of ACT12is performed. In a case where the resist ON signal is not generated (ACT11: NO), the process of ACT11is performed again.

After the process of ACT11is ended, a process of ACT12is performed. In ACT11, it starts to convey the sheet P toward the secondary transfer position. Specifically, the conveying controller112drives the resist roller drive motor M45and rotates the resist roller45. The sheet P receives the drive forces of the resist rollers45and the paper feed roller43A and is conveyed through the first conveying path41toward the secondary transfer position. At this time, the course of the sheet P coincides with the standard course. In this manner, the process of ACT11is ended.

When the sheet P moving in the first conveying path41arrives at the secondary transfer position, the toner image is transferred from the intermediate transfer belt33A. When the sheet P arrives at the fuser50, the toner image is fused on the sheet P by the fuser50. The sheet P passed through the fuser50is ejected to the paper ejection plate103aby the paper ejection rollers60or is conveyed by the inverting device105for the double-sided printing. In this manner, the image forming system100forms the image on the sheet P.

As described above, the sheet conveying apparatus1according to this embodiment can inhibit the skew of the edge F of the sheet P fed to the printer103and the horizontal deviation of the sheet P in the first conveying orthogonal direction D2. Thus, the image forming system100prevents the image formed on the sheet P from skewing or horizontally deviated to the sheet P. According to sheet conveying apparatus1of this embodiment, if at least one of the skew and the horizontal deviation occurs on the conveying path where the sheet P is fed from the manual feeding paper feeding tray106ato the course correcting unit46, the course of the sheet P can coincides with the standard course until the sheet P arrives at the resist roller45. For example, even if the manual feeding guide106bis loose or the operator roughly sets the sheets P on the manual feeding paper feeding tray106a,the course of each sheet P can coincide with the standard course.

In the above-described embodiments, the sheet conveying apparatus1is described. However, the sheet conveying apparatuses2and3also have the course correcting unit46and it is thus possible to inhibit the skew of the edge of the sheet and the horizontal deviation of the sheet in the direction orthogonal to the conveying direction similar to the sheet conveying apparatus1.

As described above, according to at least one embodiment, there can be provided a sheet conveying apparatus and an image forming system that can inhibit the skew of the edge of the sheet and the horizontal deviation of the sheet in the direction orthogonal to the conveying direction.

Note that, in the above-described embodiments, the sheet conveying apparatus used for the manual paper feeding device106, the paper feeding device104, and the inverting device105is described. However, the sheet conveying apparatus may be used for conveying the original document as the sheet. For example, the sheet conveying apparatus may be used for the ADF102. In this case, a resist member in a last stage of the aligning mechanism may be a plate-shaped stopper.

In the above-described embodiments, the sheet conveying apparatus1having the first contact/separate mechanism48, the second contact/separate mechanism44A, and the third contact/separate mechanism44B is described. However, depending on the arrangement distance among the resist roller45, the course correcting unit46, and the roller conveying mechanism43, the sheet conveying apparatus1does not have at least one of the first contact/separate mechanism48, the second contact/separate mechanism44A, and third contact/separate mechanism44B, the course may be appropriately corrected by the course correcting unit46. In this case, the sheet conveying apparatus1may not have at least one of the first contact/separate mechanism48, the second contact/separate mechanism44A, and the third contact/separate mechanism44B.

The above-descried embodiments illustrate that the second contact/separate mechanism44A moves the separation roller43C such that the paper feed roller43A does not press the sheet P. However, the separation roller43C may be fixed and the paper feed roller43A may be moved to perform the contact/separate action. Furthermore, both the separation roller43C and the paper feed roller43A may be moved to perform the contact/separate action.

The above-descried embodiments illustrate that the roller conveying mechanism43has the pick-up roller43B and the separation roller43C. However, the paper feeding method and the separation method are not limited thereto. For example, in a case where a separation pad method is used, the separation pad is separated from the paper feed roller. Then, it is possible to perform the contact/separate action similar to the second contact/separate mechanism44A.

The above-descried embodiments illustrate that the aligning mechanism42has the resist rollers45and the course correcting unit46. However, if it is possible to form paper slack between the course correcting unit46and the roller conveying mechanism43while the resist ON signal is waited, the aligning mechanism42may not have the resist roller45. In this case, the following modifications may be added to the above-described embodiments. For example, after the process of ACT4inFIG. 9, the course correcting roller drive motor M46is stopped and the processes of ACTS to7are performed. Thereafter, the process of ACT8is omitted. After the process of ACT9is performed, the process of ACT10is omitted, and the process of ACT11is performed. Furthermore, in ACT12, it starts to drive the first course correcting rollers46A and the second course correcting rollers46B.