1. Field of the Invention
The present invention relates to a sheet discharging device, an image forming system, and a sheet discharging method.
2. Description of the Related Art
Conventionally, there has widely been known a sheet processing apparatus that executes various post-processes, including alignment, binding, folding, and bookbinding, to a sheet discharged from an image forming apparatus, the sheet processing apparatus being referred to as a sheet post-processing apparatus because it executes the post-processes. The sheet processing apparatus described above has popularly been used. The sheet post-processing apparatus of this type has been greatly expected to handle variety of sheets in recent years. Especially, a color image forming apparatus frequently prints an image on a coated paper (hereinafter referred to as coat paper) that looks the image wonderful for a catalog or leaflet. The coat paper generally has characteristics of:
1) having high surface smoothness;
2) having strong adhesion force between papers; and
3) having low Clark stiffness.
Therefore, these characteristics might deteriorate a stacking property of the coat paper. Specifically, when sheets that have high surface smoothness or that are easy to be charged such as coat paper are discharged and stacked, the discharged sheet might be adsorbed on a stacking surface of a tray unit or on a stacked sheet, resulting in that the discharged sheet might be buckled, or the discharged sheet might push the stacked paper to deteriorate the stacking property.
In view of this, Japanese Laid-open Patent Publication No. 2011-057313 describes a sheet discharging device having a discharging unit that discharges a sheet having an image formed thereon in a sheet discharging direction; and a tray unit that successively stacks the sheets discharged by the discharging unit, the apparatus further including a blowing mechanism that can repeat an operation of blowing air to the back surface of the sheet, one by one, discharged by the discharging unit and of stopping the blowing operation just before the trailing end of the sheet completely passes through the discharging unit. In this invention, air is sent from an air blower located below the sheet discharging unit in order to form an air layer between the lower surface of the discharged sheet and the sheets that have already been stacked, whereby the stacking property is enhanced.
Japanese Laid-open Patent Publication No. 2001-242769 describes an image forming apparatus having an image forming unit that develops an electrostatic latent image formed on an image carrier with toner to form an image onto a sheet material; a sheet material tray unit that stacks the sheet material having the image formed by the image forming unit; and an air blower that evacuates air in the apparatus to the outside and that sends air to the sheet material stacked on the sheet material tray unit, the apparatus further including a control unit that controls a blowing condition of the air blower according to the state of the sheet material stacked on the sheet material tray unit, in order to stabilize the stacking property of the sheet materials on a discharge tray without causing stain on the sheet material or without causing a stacking trouble that means the sheet materials are adhered to each other on the discharge tray for the sheet materials having the image formed thereon.
However, on the sheet tray unit in the inventions described in Japanese Laid-open Patent Publication No. 2011-057313 and Japanese Laid-open Patent Publication No. 2001-242769, a stacking trouble might be caused by the change in the condition such as a type of a sheet, a size of a sheet, or a thickness of a sheet. Specifically, when air is sent from the air blower even after the discharged sheet completely passes through a nip of a discharging roller, the discharged sheet is blown by airflow, so that the drop position is not fixed. Accordingly, the stacking trouble might be caused. Since the air blower is always opened, foreign matters enter the apparatus, which might damage a mechanism in the apparatus.
Therefore, there is a need to secure a satisfactory stacking property upon discharging a sheet by blowing air, and to prevent foreign matters from entering a blowing port.
It is an object of the present invention to at least partially solve the problems in the conventional technology.
According to an embodiment, there is provided a sheet discharging device that includes a discharging unit configured to discharge a sheet; an air blower configured to blow air to a lower surface of the sheet discharged by the discharging unit; a blocking unit configured to block at least some of the air blown to the lower surface of the sheet from a blowing port of the air blower; and a control unit configured to controls the operation of the blocking unit.
According to another embodiment, there is provided an image forming system that includes the sheet discharging device according to the above embodiment.
According to still another embodiment, there is provided a sheet discharging method that includes discharging a sheet by a discharging unit; blowing air by an air blower to a lower surface of the sheet discharged by the discharging unit; and blocking, by a blocking unit, at least some of the air blown to the lower surface of the sheet from a blowing port of the air blower to control an amount of blocking the air. The blocking includes bringing the blocking unit into a closed state during a stand-by state for a discharge of the sheet; bringing the blocking unit into a state of blowing a predetermined volume of air while the sheet is discharged by the discharging unit; and bringing the blocking unit into a state of stopping the blowing of air by the air blower or reducing the air blown after the sheet completely passes through the discharging unit.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
The present invention is characterized in that a blocking member is provided at the downstream side of an air blower, and air is sent from the air blower to a portion between a stacking tray or a sheet that has already been stacked and a lower surface of a sheet to be discharged, in order to realize satisfactory stacking property. Embodiments of the present invention will be described below with reference to the drawings.
In each embodiment, the same components or components regarded to be the same are identified by corresponding reference numerals, and the description will not be repeated as the case may be. In the embodiments described below, the term “sheet” means a sheet-like recording medium including a recording sheet, a transfer sheet, and an OHP sheet.
In
The image processing circuit converts inputted image data into image data that can be printed, and the optical writing device performs optical writing to a photosensitive element based upon an image signal outputted from the image processing circuit. The developing unit develops a latent image, formed on the photosensitive element by the optical writing, with toner, and the transfer unit transfers the toner image that is made visible by the developing unit onto a sheet. The fixing unit fixes the toner image transferred to the sheet by applying heat and pressure. The image forming apparatus PR uses electrophotography as described above. However, known image forming apparatuses using an inkjet system or thermal transfer system can all be used. In the present embodiment, the image processing circuit, the optical writing device, the developing unit, the transfer unit, and the fixing unit form an image forming unit.
The sheet post-processing apparatus PD is mounted at the side of the image forming apparatus PR. The sheet discharged from the image forming apparatus PR is guided to the sheet post-processing apparatus PD. The sheet post-processing apparatus PD has a conveying path A, a conveying path B, a conveying path C, a conveying path D, and a conveying path H. The sheet is firstly guided to the conveying path A having a post-processing unit (in this embodiment, a punch unit 100 serving as a punching unit) that performs a post-process to one sheet.
The conveying path B guides the sheet to an upper tray 201 through the conveying path A, and the conveying path C guides the sheet to a shift tray 202. The conveying path D guides the sheet to a process tray F (hereinafter also referred to as “end-face binding process tray” below) that performs an alignment, stapling process and the like. It is configured that the sheet is sorted to the conveying path B, C, or D from the conveying path A by a bifurcating claw 15 and a bifurcating claw 16.
The sheet post-processing apparatus can perform various processes, such as a punching process (punch unit 100), a sheet alignment+end binding process (jogger fence 53, end-face binding stapler S1), a sheet alignment+saddle-stitching process (saddle-stitching upper jogger fence 250a, saddle-stitching lower jogger fence 250b, saddle-stitching stapler S2), a sheet sorting process (shift tray 202), a center-folding process (folding plate 74, folding roller 81), to the sheet. Therefore, the conveying path A, as well as the conveying path B, the conveying path C, and the conveying path D that are subsequent to the conveying path A are selected. The conveying path D includes a sheet accommodating unit E, and at the downstream side of the conveying path D, the end-face binding process tray F, a saddle-stitching folding process tray G, and the discharge conveying path H are mounted.
The conveying path A that is common for the conveying path B, the conveying path C, and the conveying path D at their upstream side is provided with an inlet sensor 301 that detects a sheet accepted from the image forming apparatus PR, and is provided with, at its downstream side, an inlet roller 1, the punch unit 100, a punch crumb receiver 101, a conveying roller 2, and the first and second bifurcating claws 15 and 16 in this order. The first and second bifurcating claws 15 and 16 are held in a state (initial state) illustrated in
When the sheet is guided to the conveying path B, the state illustrated in
The sheet is sorted on a shift tray discharging unit located at the most downstream side of the sheet post-processing apparatus PD. The shift tray discharging unit includes a pair of shift-discharging rollers 6 (6a, 6b), a returning roller 13, a sheet surface detecting sensor 330, the shift tray 202, a shift mechanism that is not illustrated and that allows the shift tray 202 to reciprocate in a direction orthogonal to the sheet conveying direction, and a shift tray lifting and lowering mechanism that lifts and lowers the shift tray 202.
When the sheet is guided to the conveying path D, the first solenoid that drives the first bifurcating claw 15 is turned ON, and the second solenoid that drives the bifurcating claw 16 is turned OFF. With this, the bifurcating claw 15 swings upward, and the bifurcating claw 16 swings upward, whereby the sheet is guided to the conveying path D from the conveying roller 2 through the conveying roller 7. The sheet guided to the conveying path D is guided to the end-face binding process tray F. The sheet that undergoes the alignment, stapling process and the like on the end-face binding process tray F is sorted by a guide member 44 to the conveying path C that guides the sheet to the shift tray 202 and to the saddle-stitching and folding process tray G (hereinafter also merely referred to as “saddle-stitching process tray” below) that performs the folding process and the like. When the sheet is guided to the shift tray 202, the sheet bundle is discharged to the shift tray 202 from the pair of discharging rollers 6. The sheet bundle guided to the saddle-stitching process tray G undergoes the folding and binding process on the saddle-stitching process tray G, and is discharged to a lower tray 203 from a discharging roller 83 via the discharge conveying path H.
On the other hand, a bifurcating claw 17 is arranged in the conveying path D, and it is held in a state illustrated in the figure by a low-load spring not illustrated. After the trailing end of the sheet conveyed by the conveying roller 7 passes through the bifurcating claw 17, at least the conveying roller 9 out of the conveying rollers 9 and 10, and a staple discharging roller 11 is rotated backward to allow the sheet to move backward along a turn guide 8. With this process, the sheet can be guided to the sheet accommodating unit E from the trailing end of the sheet, stayed (pre-stacked) thereon, superimposed on the next sheet, and then, conveyed. Two or more sheets can be conveyed as being superimposed with each other by repeating this operation. A pre-stack sensor 304 is mounted to set a backward feed operational timing upon pre-stacking the sheet.
When the sheet alignment and end-binding process are performed, the sheet is guided to the conveying path D, and the sheet guided to the end-face binding process tray F by the staple discharging roller 11 is successively stacked on the end-face binding process tray F. In this case, the trailing end of the sheet abuts against a reference fence 51, one by one, by a hammer roller 12, whereby the sheet is aligned in the vertical direction (in the sheet conveying direction). The sheet is also aligned in the lateral direction (the direction orthogonal to the sheet conveying direction; also referred to as a sheet widthwise direction) by the jogger fence 53. The end-face binding stapler S1 serving as the binding unit is driven by a staple signal from a control unit, not illustrated, on an intermission of the job, i.e., between the last sheet of the sheet bundle and the top sheet of the next sheet bundle, whereby the binding process is executed. The sheet bundle to which the binding process is executed is immediately sent to the shift-discharging roller 6 by an ejection belt 52 (see
As illustrated in
An ejection belt HP sensor 311 detects a home position of the ejection claw 52a. The ejection belt HP sensor 311 is turned on or off by the ejection claw 52a provided to the ejection belt 52. Two ejection claws 52a are arranged on the outer peripheral surface of the ejection belt 52 on opposite positions for alternately conveying the sheet bundle accommodated on the end-face binding process tray F. According to need, the ejection belt 52 is rotated backward to align the leading end of the sheet bundle, accommodated on the end-face binding process tray F, in the conveying direction by the back surface of the ejection claw 52a that is opposite to the ejection claw 52a waiting to move the sheet bundle.
In
In
After the completion of the alignment process, the binding process is carried out by the end-face binding stapler S1. As apparent from the perspective view in
As illustrated in
The detailed configuration of each component will be described. Driving force of the driving shaft 37 is transmitted to a roller 36 of the conveying mechanism 35 via a timing belt. The roller 36 and the driving shaft 37 are coupled and supported by an arm, whereby the conveying mechanism can swing with the driving shaft 37 serving as a rotation fulcrum. The roller 36 of the conveying mechanism 35 is driven to swing by a cam 40. The cam 40 rotates about a rotating shaft, and is driven by a motor not illustrated. A driven roller 42 is arranged at the position opposite to the roller 36 in the conveying mechanism 35. The driven roller 42 and the roller 36 nip the sheet bundle, and apply pressure by an elastic member to exert conveying force.
A conveying path for turning the sheet bundle from the end-face binding process tray F to the saddle-stitching process tray G is formed between the ejection roller 56 and an inner surface of the guide member 44 opposite to the ejection roller 56. The guide member 44 pivots about a fulcrum, and its drive is transmitted from a bundle bifurcating drive motor 161 (see
When the sheet bundle SB is conveyed from the end-face binding process tray F to the saddle-stitching process tray G, the trailing end of the sheet bundle SB aligned on the end-face binding process tray F is pushed up by the ejection claw 52a, and then, the sheet bundle is nipped between the roller 36 of the conveying mechanism 35 and the driven roller 42 opposite to the roller 36, whereby conveying force is applied to the sheet bundle. In this case, the roller 36 of the conveying mechanism 35 waits on a position not in contact with the leading end of the sheet bundle SB. Then, the roller 36 of the conveying mechanism 35 is brought into contact with the surface of the sheet after the leading end of the sheet bundle SB passes, so as to apply conveying force. In this case, the guide member 44 and the ejection roller 56 form a turn conveying path, by which the sheet bundle SB is conveyed to the saddle-stitching process tray G at the downstream side.
As illustrated in
A bundle conveying roller top 71 is mounted at the upper part of the bundle conveying guide plate top 92, while a bundle conveying roller bottom 72 is mounted at its lower part. A saddle-stitching upper jogger fence 250a is arranged on both sides along the side face of the bundle conveying guide plate top 92 so as to cross both rollers 71 and 72. Similarly, a saddle-stitching lower jogger fence 250b is mounted on both sides along the side face of the bundle conveying guide plate bottom 91. A saddle-stitching stapler S2 is arranged on the portion where the saddle-stitching lower jogger fence 250b is mounted. The saddle-stitching upper jogger fence 250a and the saddle-stitching lower jogger fence 250b are driven by a drive mechanism, not illustrated, to perform the alignment process in the direction (the sheet widthwise direction) orthogonal to the sheet conveying direction. The saddle-stitching stapler S2 includes paired clincher unit and driver unit, and two pairs are provided with a predetermined space in the sheet widthwise direction.
A movable reference fence 73 is arranged to cross the bundle conveying guide plate bottom 91, and it can move in the sheet conveying direction (in the vertical direction in
The center-folding mechanism is provided almost on the center of the saddle-stitching process tray G, and includes a folding plate 74, a pair of folding rollers 81, and the conveying path H that conveys the folded sheet bundle.
In the present embodiment, a detection lever 501 that detects a height of the stack of the center-folded sheet bundle is mounted on the lower tray 203 so as to be capable of swinging about a fulcrum 501a. A sheet surface detection sensor 505 detects an angle of the detection lever 501, and a later-described CPU 401 controls the upward and downward movement of the lower tray 203 based upon the detected angle for detecting overflow.
The sheet discharged from the image forming apparatus PR is discharged onto the shift tray 202 from the discharging portion J, and stacked onto the shift tray 202. In order to prevent the sheet from being stacked in a random fashion, after the sheet is discharged, the returning roller 13 rotates to be in contact with the sheet for returning the sheet in the direction of the end fence 210, and brings the trailing end of the sheet to be in contact with the end fence 210 to align the sheet in the sheet conveying direction. As illustrated in
However, the discharge tray having the configuration described above has the problem described above, when a sheet P having high smoothness, such as a coat paper, is stacked. For example, when a following sheet P2 is discharged with a preceding sheet P1 being stacked onto the shift tray 202 as illustrated in
In the present embodiment, a blowing device is provided in order to prevent the discharge trouble and stacking trouble described above.
Air is sent between the upper surface of the stacked sheet (preceding sheet P1) and the lower surface of the discharged sheet (following sheet P2) (in the case of the first sheet, between the stacking surface of the shift tray 202 and the lower surface of the discharged sheet P2) as illustrated in
In the present embodiment, the first blowing device 230a is provided at the far side of the device, and the second blowing device 230b is provided at the near side of the device, and air is sent to the lower surface of the discharged sheet P2 from two portions on both ends in the widthwise direction of the discharged sheet P2 (the direction orthogonal to the sheet conveying direction). In this case, if air is blown toward the inside from the first and second blowing devices 230a and 230b, even a small-sized sheet can enjoy the effect of the blowing devices.
In the example in
When an air volume during the blowing is equal to all types of sheets (type of sheet, sheet size, thickness of sheet), the air volume is insufficient depending upon the type of the sheet, so that the effect of preventing the discharge trouble or stacking trouble might not be realized. There may be the case in which the sheet is blown by excessive air volume. When air is sent even after the discharged sheet (following sheet) P2 completely passes through the nip of the discharging roller 6, the discharged sheet (following sheet) P2 is carried by airflow when falling onto the shift tray 202, so that the falling position becomes unstable. When the falling position becomes unstable, the stacked position becomes non-uniform, which causes stacking trouble.
In view of this, in the present embodiment, a blocking member 231 for closing the blowing portion 230-1 of the sheet post-processing apparatus PD is provided as illustrated in
During the stand-by state of the sheet discharging portion in which the sheet is not discharged from the sheet discharging portion J, the blocking member 231 is located on an ascending position where the blocking member closes the blowing port 230-2 as illustrated in
In
A program code for the control of the image forming apparatus PR is stored in the ROM 412. The CPU 411 reads the program code from the ROM 412, and develops the same on the RAM 413. The CPU 411 stores the data necessary for the control onto the RAM 413, and executes the program defined by the program code as using the RAM 413 as a work area, thereby controlling the respective units. A motor used for an image forming unit such as a photosensitive element, various DC loads 450 and various AC loads 470 such as various motors or clutches in the paper feeding unit, a paper conveying path, a duplex conveying path and the like, and various sensors 460 such as a temperature sensor for detecting the temperature of the fixing roller are connected to the image forming apparatus control unit 410. An image reading device 300 and an operation display unit 440 are also connected to control the respective units via the image forming apparatus control unit 410.
The control of the sheet post-processing apparatus PD is executed by the sheet post-processing apparatus control unit 400 as described above. A program code for the control is stored in the ROM 402. The CPU 401 reads the program code from the ROM 402, develops the same on the RAM 403, and stores the data necessary for the control onto the RAM 403. The CPU 401 then executes the control defined by the program code, as using the RAM 403 as a work area, thereby controlling various DC loads 420. The DC loads 420 include, for example, a discharging motor that drives the discharging roller 6, a returning motor that drives the returning roller 13, a motor 232 that drives to move the blocking member 231 up and down, a blowing motor that drives a blowing fan of the blowing device 230, and a lifting and lowering motor that lifts and lowers the shift tray 202.
The image forming apparatus PR and the sheet post-processing apparatus PD send and receive commands necessary for the post-processing control via the serial I/F 415 and 404 as described above. The CPU 401 of the sheet post-processing apparatus PD executes various controls including the ascending and descending control of the discharging roller 6, the returning roller 13, and the blocking member 231, the control (ascending and descending control) of the position of the height of the shift tray 202, the drive control of the blowing motor, and a control procedure illustrated in respective flowcharts described later, from the command and sheet position information acquired from various sensors 430 including a later-described sensor Se1.
After the blowing device 230 starts to send air (step S101), the sheet post-processing apparatus PD receives sheet information (type of sheet, sheet size, thickness of sheet: I101) from the image forming apparatus PR, and then, the CPU 401 determines a descending amount Y mm (opening amount) of the blocking member of the blowing portion 230-1 based upon the sheet information (step S102). The sheet post-processing apparatus PD also receives information (I102) about the conveying distance X mm to the nip of the discharging roller 6 and a linear velocity V mm/s from the sheet detection sensor Se1, and determines an opening start time Δt1 and an opening time Δt2 of the blowing portion 230-1 (steps S103, S104). The procedure of determining the descending amount of the blocking member in step S102 is illustrated in
When the thickness of the sheet is equal to or larger than T g/m2 as a result of the determination in step S203, the descending amount of the blocking member 231 is set as a descending amount L1 set beforehand (step S204). When the thickness of the sheet is less than T g/m2 as a result of the determination in step S203, the descending amount of the blocking member 231 is set as L2 that is not more than L1 (step S205). When the sheet size is smaller than the size of X mm in length and Y mm in width as a result of the determination in step S202, the descending amount of the blocking member 231 is set as L3 that is not more than L2 (step S206). When the sheet is determined not to be the coat paper in the determination in step S201, the descending amount of the blocking member 231 is set as L4 not more than L3 (step S207).
As understood from this procedure, the descending amount of the blocking member is set as L1 when the sheet is the coat paper, the sheet size is equal to or larger than the size of X mm in length and Y mm in width, and the thickness of the sheet is equal to or larger than T g/m2 in the present embodiment. When the sheet is the coat paper, the sheet size is equal to or larger than the size of X mm in length and Y mm in width, and the thickness of the sheet is smaller than T g/m2, the descending amount L2 of the blocking member is set to be not more than the descending amount L1. When the sheet is the coat paper, and the sheet size is smaller than the size of X mm in length and Y mm in width, the descending amount L3 of the blocking member is set to be not more than the descending amount L2. When the sheet is not the coat paper, the descending amount L4 of the blocking member is set to be not more than the descending amount L3.
The sheet size of X mm in length and Y mm in width, and the thickness of the sheet T g/m2, which are the threshold values, and the descending amounts L1, L2, L3, and L4 are experimentally obtained, and stored in the ROM 402 in the form of a table. The CPU 401 takes these values into the RAM 403 when using, and refers to according to need. The descending amount Y mm of the blocking member can manually be adjusted by a user or a service man from the operation display unit 440 of the image forming apparatus PR.
When the air volume cannot be adjusted, the sheet might be blown, if air corresponding to the condition that the sheet is a coat paper having the size equal to or larger than X mm in length and Y mm in width, and having the thickness equal to or larger than T g/m2 is sent to the sheet satisfying the condition that the sheet is a coat paper having a size less than X mm in length and Y mm in width, due to excessive air volume. Further, even if air corresponding to the condition that the sheet is a coat paper having a size less than X mm in length and Y mm in width is sent to the sheet satisfying the condition that the sheet is a coat paper having a size equal to or larger than X mm in length and Y mm in width, and having a thickness equal to or larger than T g/m2, the effect of preventing the adhesion cannot be obtained due to insufficient air volume. However, as in the present embodiment, the insufficient air volume and excessive air volume can be prevented by adjusting the air volume through the control of the descending amount of the blocking member 231 based upon the sheet information I101 including the sheet-type information I201, the sheet-size information I202, and the sheet-thickness information I203. This structure can prevent the discharge trouble and stacking trouble, which are caused by the insufficient air volume, and the blow of the sheet caused by the excessive air volume.
Since the blowing portion 230-1 is opened Δt1 second after the detection of the leading end of the sheet based upon the sheet detection information acquired from the sheet detection sensor Se1, and the blowing portion 230-1 is closed Δt2 second after the detection of the leading end of the sheet, the blowing portion 230-1 can be opened and closed according to the sheet discharging timing. When the discharged sheet P2 falls onto the shift tray 202, the blowing portion 230-1 is closed, so that air is not sent to the shift tray 202. Therefore, the stacking trouble caused by airflow can be prevented.
A second embodiment describes a structure in which a shutter is mounted in a fan duct on both ends of the discharging portion in order to control volume of air emitted from a duct exhaust port.
An image forming apparatus and a sheet post-processing apparatus are the same as the image forming apparatus PR and the sheet post-processing apparatus PD described with reference to
However, the discharge tray having the configuration described above has the problem described above, when a sheet P having high smoothness, such as a coat paper, is stacked. When a following sheet P2 is discharged with a preceding sheet P1 being stacked onto the shift tray 202 as illustrated in
In the present embodiment, the configuration of the discharging portion illustrated in
In
The pressing member 14 presses the sheet, only when the sheet that is a coat paper passes. Although described later, the CPU 401 of the sheet post-processing apparatus PD determines whether the sheet is a coat paper or not based upon the sheet-type information transmitted from the image forming apparatus PR for controlling the operation.
After the alignment process in the conveying direction and in the widthwise direction is completed, the pressing member 14 presses the trailing end of the preceding sheet P1 before the following sheet P2 is brought into contact with the preceding sheet P1 as illustrated in
The driving mechanism 18 includes a first shaft 19a, a second shaft 19b, a returning roller drive motor 20 that rotates the first shaft 19a, a drive gear 20a, a driven gear 20b, first to third gears 21, 22, and 23, and a cam 24.
The returning roller drive motor 20 has the drive gear 20a on its leading end of a rotating shaft. The drive gear a is meshed with the driven gear 20b mounted to one end of the first shaft 19a, so that it can rotate the first shaft 19a forward and backward.
The first gear 21 meshed with the second gear 22 that is mounted on one end of the second shaft 19b is mounted to the first shaft 19a, so that the driving force of the returning roller drive motor 20 can be transmitted to the second shaft 19b. One-way clutches 21a and 22a that lock when the first gear 21 and the second gear 22 rotate in the inverse direction are provided respectively to the first gear 21 and the second gear 22.
A pair of third gears 23 is provided symmetric with respect to the center of the sheet P in the conveying direction, and is fixed to the second shaft 19b. With this structure, the third gears 23 rotate together with the rotation of the second shaft 19b. The third gears 23 are meshed with gear positions of a pair of cams 24 mounted to the first shaft 19a for driving the cams 24. The cams 24 are not fixed to the first shaft 19a, so that they rotate only when the third gears 23 rotate. Each of the pair of pressing members 14 is supported to a support shaft 14d (see
In the driving mechanism 18 thus configured, the returning roller drive motor 20 is used as a driving source. In
When the returning operation of the returning roller 13 is completed, the pressing operation is started. As illustrated in
According to the driving mechanism thus configured, the preceding sheet P1 that is adhered due to the adhesion force between the sheets is held after being returned by the returning roller 13. Accordingly, excellent alignment precision can be realized. Since the returning roller 13 and the pressing member 14 are driven by the same driving source, a miniaturization and cost reduction can be attained. In this case, the changeover between the returning operation and the pressing operation can be carried out only by changing the direction of the rotation of the returning roller drive motor 20.
A pair of blowing devices 230 is provided at the outside (on both ends) of the pair of discharging rollers 6, which are mounted on four portions in the widthwise direction of the sheet (the direction orthogonal to the sheet conveying direction D1) in
The blowing port 238 is opened at the most downstream side of the blowing duct 237. As illustrated in
The blowing duct 237 is located below the conveying path C. It deflects the airflow sent obliquely upward by the blowing fan 236 along the shape of the blowing duct 237, thereby sending air from the blowing port 238 as described above.
When the preceding sheet P1 is absent, and the sheet P1 is directly discharged onto the shift tray 202, air is similarly sent to the back surface of the sheet P1 to form the air layer AL between the sheet P1 and the shift tray 202 for preventing the adhesion between the sheets. In this case, the guide surface 237a of the blowing duct 237 in the blowing device 230 and the stacking surface 202b of the shift tray 202 have the same angle with respect to the horizontal direction, whereby air is sent parallel to the stacking surface 202b of the shift tray 202. Specifically, air W parallel to the stacking surface 202b is sent.
On the other hand, air W from two blowing devices 230 (230a, 230b) joins or crosses on or above an X point on the stacking surface 202b of the shift tray 202 as illustrated in
Therefore, when the louver 239 is fixed, and the sheet that is most frequently used is discharged onto the shift tray 202, it is reasonable that the crossing point X is set on the position corresponding to the leading end of this sheet.
When air W is sent from the blowing devices 230a and 230b from both ends of the sheet P toward the center of the sheet P in the widthwise direction and toward the leading end of the sheet P discharged onto the shift tray 202 as described above, the air layer AL can be formed all over the sheet surface of the discharged sheet P in the widthwise direction and feeding direction. The formation of the air layer AL can effectively prevent or reduce the adhesion force between the sheets. As a result, the buckling of the following sheet P2 or the adhesion of the following sheet P2 to the preceding sheet P1 can be prevented, whereby satisfactory alignment precision can be attained.
The blocking member 241 is assembled to a blocking member driving shaft 242 that is arranged to cross the blowing path of the blowing port 238 in the horizontal direction. An extension spring mounting member 243 is fixed to a portion of the blocking member driving shaft 242 projecting toward the outside of the discharging unit JU, and applies elastic force to the blocking member 241 by an extension spring, not illustrated, in the direction of closing the blowing path 240 at all times. A cam follower 244 for swinging the blocking member 241 is fixed to the blocking member driving shaft 242 at the side opposite to the side where the extension spring mounting member 243 is mounted. A cam 245 that drives the cam follower 244 is provided on both ends of a cam driving shaft 246.
In these figures, the cam driving shaft 246 is mounted between the first and second blowing devices 230a and 230b via a shaft bearing 246a at the upper part of the discharging unit JU, and the cam 245 is arranged on the position where the cam 245 can drive the cam follower 244. As apparent from
The second shaft 19b is driven by the returning roller drive motor 20 through the first shaft 19a. Therefore, the returning roller drive motor 20 drives the returning roller 13, the pressing member 14, and the blocking member 241. Specifically, the driving source of the blocking member 241 is the same as the driving source of the returning roller 13 and the pressing member 14. With this structure, during the operation of the returning roller 13, the blocking member 241 is not operated (closed state). On the other hand, during the operation of the pressing member 14, the returning roller 13 does not rotate, but the blocking member 241 of the blowing devices 230a and 230b opens the blowing path 240 in synchronism with the operational timing of the pressing member 14.
The pressing member 14 prevents the stacked sheet from being pushed out by pressing the trailing end of the sheet P stacked onto the shift tray 202 during the discharge of the sheet to be discharged. The blocking member 241 is operated on the same operational timing of the pressing member 14, in order that air is sent from the blowing device 230 during when the discharged sheet is discharged by the pair of discharging rollers 6. After the trailing end of the discharged sheet completely passes through the discharging rollers 6, the blocking member 241 is returned to the initial position to close the blowing path 240.
The blocking member 241 is opened and closed by the structure in which the cam driving shaft 246 is driven by the timing belt 247 from the second shaft 19b that drives the pressing member 14, and the cam follower 244 is driven by the cam 245 mounted on both ends of the cam driving shaft 246, as described above. Accordingly, the driving mechanism including the driving source of the returning roller 13 can be used, and the pressing member 14 and the blocking member 241 can be driven in synchronism with each other by a simple system.
The blocking member 241 is formed to have a sectional shape similar to the sectional shape of the duct 237 as illustrated in (a) of
On the other hand, when the blocking member 241 is closed, the blocking member 241 rotates in the direction orthogonal to the flow of the air so as to close the blowing path 240 at the back side of the blocking member 241 as illustrated in (b) of
When air W is sent from the blowing device 230 on both ends of the sheet P toward the center of the sheet P in the widthwise direction and toward the leading end of the sheet P discharged onto the shift tray 202 as described above, the air layer AL can be formed all over the sheet surface of the discharged sheet P in the widthwise direction and feeding direction. The formation of the air layer AL can effectively prevent or reduce the adhesion force between the sheets. As a result, the buckling of the following sheet P2 or the adhesion of the following sheet P2 to the preceding sheet P1 can be prevented, whereby satisfactory alignment precision can be attained.
Since the volume of air sent from the blowing device 230 after the discharge of the sheet can be reduced by the blocking member 241, the lift of the trailing end of the discharged following sheet can also be prevented. The prevention of the lift leads to the enhancement of the alignment precision.
In the present embodiment, the blowing control is also executed by the configuration same as that in the image forming system illustrated in
As described above, a blowing mode for sending air to the back surface (lower surface) of the sheet from the blowing device 230 is set in the present embodiment. The blowing mode is turned ON when a user selects a coat paper on the operation panel 105. However, air is not sent even if a sheet is a coat paper, when a user selects a forced OFF. In the case of a plain paper, air is not sent in default, but air can be sent by selecting a forced ON.
In the process of selecting the blowing mode, the process of the blowing mode is started when a user selects “ON” 440b from the selection screen 440a of the blowing mode on the operation display unit 440 in
Specifically, when a coat paper is selected, it is set such that the blowing fan 230 is turned ON. Therefore, before the blowing fan 230 is turned ON, it is determined whether the forced OFF of the blowing fan 230 is selected or not (step S303). When the forced OFF is selected (step S303: YES), the blowing fan 230 is turned OFF (step S304), and then, the CPU 401 exits the routine.
When the forced OFF is not selected (step S303: NO), the blowing fan 230 is turned ON (step S305) to generate airflow (air W), and then, the CPU 401 exits the routine.
The blowing OFF is set in the default for a sheet other than the coat paper. Therefore, the CPU 401 also determines whether the forced blowing OFF is selected or not (step S306). When the forced blowing OFF is selected (step S306: YES), the blowing fan 230 is turned ON (step S305). When the forced blowing OFF is not selected (step S306: NO), the blowing fan 230 is turned OFF (step S307), and then, the CPU 401 exits the routine.
When the user selects “OFF” 440c on the blowing mode screen, the blowing mode is not started, and the general discharge process is executed.
In the present embodiment, when the user selects the sheet-type information on the operation display unit 440, the blowing mode is turned ON. When the user selects the forced OFF, air is not sent. In the case of a plain paper, air is not sent in the default. However, air can be sent when the user selects the forced ON.
The units not particularly described are configured to be the same as those in the first embodiment, and function similarly.
As described above, the present embodiment can provide effects described below.
1) In the present embodiment, the discharging portion J or the discharging unit JU (sheet discharging device) includes the discharging roller 6 (discharging unit) that discharges the sheet P, the blowing device 230 (blowing unit) that sends air to the lower surface of the sheet P discharged by the discharging roller 6, blocking members 231 and 241 (blocking unit) that blocks the blow of air to the lower surface of the sheet P from blowing ports 230-2 and 238 of the blowing device 230, and the CPU 401 (control unit) that controls the operation of the blocking members 231 and 241.
With this structure, the blowing timing is set by the control of the operation of the blocking members 231 and 241 for sending air; air can be sent with the blowing timing being set, whereby satisfactory stacking property can be attained upon discharging a sheet; the blowing port 230-2 can be opened and closed by the blocking member 231, and the blowing port 238 can be opened and closed by the blocking member 241, so that the intrusion of foreign matters into the blowing ports 230-2 and 238 can be prevented; the intrusion of foreign matters can be prevented, so that malfunction caused by the intrusion of foreign matters can be prevented from occurring.
2) The sheet discharging device further includes the shift tray 202 (tray unit) on which the sheet P discharged by the discharging roller 6 is stacked, and the blowing device 230 is provided near both ends of the shift tray 202 in the direction orthogonal to the discharging direction. Accordingly, air can be sent from both ends on the trailing end of the discharged sheet, whereby the satisfactory air layer AL can be formed between the preceding sheet P1 and the following sheet P2, and between the preceding sheet P1 and the stacking surface 202b of the shift tray 202. Consequently, the adhesion and buckling of the sheet P can surely be prevented, whereby satisfactory alignment precision can be attained.
3) The blowing direction of the blowing devices 230a and 230b provided near both ends is set to cross on or above the shift tray 202. Therefore, air (airflow) W crosses on the lower surface of the sheet P, so that the air layer AL having sufficient thickness can be formed about the crossing point. Accordingly, the effect described in 2) can more effectively be attained.
4) The position X where the blowing direction crosses each other is set on the center of the shift tray 202 in the widthwise direction. Therefore, air (airflow) W crosses on the lower surface of the sheet P, so that the air layer AL having sufficient thickness can be formed about the crossing point. Accordingly, the effect described in 2) can more effectively be attained.
5) The position X where the blowing direction crosses each other is set on the leading end of the sheet P discharged onto the shift tray 202. Therefore, the air layer AL can surely be formed on all over the discharged sheet P in the longitudinal direction. Accordingly, the effect described in 2) can more surely be attained.
6) The louver 239a that regulates the blowing direction toward the center of the shift tray 202 in the sheet widthwise direction is provided to the blowing device 230. Therefore, the direction of air W can be set with a simple mechanism.
7) The blowing device 230 includes the blowing duct 237, and the guide surface (blowing guide) 237a of the blowing duct 237 is arranged parallel to the stacking surface 202b of the shift tray 202. Therefore, air W can be sent from the blowing device 230 as air parallel to the stacking surface 202b. Accordingly, the satisfactory air layer AL can be formed, and the effect described in 2) can more effectively be attained.
8) The sheet discharging device includes the returning roller 13 (conveying unit) that conveys the sheet P stacked onto the shift tray 202 in the direction reverse to the sheet discharging direction; the pressing member 14 (pressing unit) that presses the conveyed sheet P; and a driving unit that drives the returning roller 13 and the pressing member 14 by the returning roller drive motor 20 (same driving source). Therefore, the preceding sheet P1 can be held by the pressing member 14, and the following sheet can be returned by the returning roller 13 with the single driving source, when the following sheet P2 is discharged. This structure can prevent the preceding sheet from being pushed out due to the adhesion between the sheets by static electricity, whereby satisfactory alignment precision can be attained. Since the returning roller 13 and the pressing member 14 are driven by the same driving source, the device can be made compact without an increase in size.
9) The CPU 401 (control unit) operates the blocking members 231 and 241 in accordance with the discharging operational timing of the sheet. Therefore, air can be sent only when the sheet is discharged. Thus, the stacking property can be enhanced.
10) The blocking member is in the closed state during the stand-by state of the sheet discharge, which can prevent foreign matters from entering the blowing ports 230-2 and 238 during the stand-by state.
11) When the sheet P is discharged by the discharging roller 6, the blocking members 231 and 241 are set to send air in a predetermined volume, and after the sheet P completely passes through the discharging roller 6, the air blow is stopped, or the air volume is reduced. Specifically, air is sent with an appropriate volume to form the air layer AL only during the discharging operation, and after the discharging operation is finished, the formation of the air layer AL is stopped, or the air blow to the trailing end of the sheet P to be discharged is stopped. Thus, satisfactory stacking property can be secured.
12) The effect described in 1) can be attained only by a simple structure in which the blocking member 231 moves up and down.
13) Since the blocking member 241 is arranged at the inside of the blowing port 238 so as to be rotatable, the effect described in 1) can be attained without allowing a person on the outside to notice the presence of the blocking member.
14) Since the blocking member 241 is arranged at the inside of the blowing port 238 so as to be rotatable, and the returning roller drive motor 20 (same driving source) drives not only the returning roller (conveying unit) and the pressing member 14 but also the blocking member 241, the pressing member can prevent the sheet from being pushed out due to the adhesion between the sheets by static electricity, and air can be sent from the blowing device 230 in synchronism with the blocking member 241. As a result, satisfactory alignment precision can be attained. Since the returning roller 13, the pressing member 14, and the blocking member 241 are driven by the same driving source, the device can be made compact without an increase in size.
15) The device includes the first and second gears 21 and 22 and the one-way clutches 21a and 22a (changeover unit) that change the operations of the returning roller 13, the pressing member 14, and the blocking member 241 according to the rotating direction of the returning roller drive motor 20. Therefore, the changeover of the operations can be made with a simple structure.
16) The driving mechanism 18 (driving unit) includes the pressing member 14 that is driven by the cam 24 that is driven by the first shaft 19a, the second gear 22 that is mounted to the second shaft 19b driving the cam 24, and the first gear 21 that transmits the rotation of the first shaft 19a to the second shaft 19b; the conveying unit includes the returning roller 13 that is mounted to the first shaft 19a and that rotates in synchronism with the first shaft 19a; and the blocking member includes the cam driving shaft 246 (first driving shaft) that pivots in synchronism with the second shaft 19b through the timing belt 247 (power transmitting unit) from the second shaft 19b, and the blocking member 241 that is mounted to the blocking member driving shaft 242 (second driving shaft) that pivots with the cam driving shaft 246, wherein the one-way clutches 21a and 22a (changeover unit) lock when the first gear 21 and the second gear 22 rotate in different direction. Therefore, the alignment operation by the returning roller 13, and the pressing operation by the pressing member 14 as well as the blowing control operation by the blocking member 241 can be changed with a simple structure.
17) The CPU 401 of the sheet post-processing apparatus PD determines the blocking amount of the sent air based upon the sheet information including at least the sheet-type information, the sheet-size information, and the sheet-thickness information transmitted from the image forming apparatus PR, and operates the blocking members 231 and 241. Therefore, air volume corresponding to the sheet to be discharged can be set, whereby the effect described in 2) can more effectively be attained.
18) The device includes a setting unit by which an operator sets the blocking amount of air by the blocking members 231 and 241 on the operation display unit 440. Therefore, the air volume corresponding to the operator's intention can be set (
The sheet in the claims corresponds to the sheets P1 and P2 (P1: stacked sheet, preceding sheet, P2: discharged sheet, following sheet), the tray unit corresponds to the shift tray 202, the discharging unit corresponds to the discharging roller 6, the air blower corresponds to the blowing devices 230, 230a, and 230b, the blowing port corresponds to the blowing ports 230-2 and 238, the blocking member corresponds to the blocking members 231 and 241, the control unit corresponds to the CPU 401, the operation unit corresponds to the operation display unit 440, the sheet discharging device corresponds to the discharging portion J or the discharging unit JU, the stacking surface corresponds to the stacking surface 202b, the air layer corresponds to the air layer AL, the crossing point corresponds to the crossing point X, the louver corresponds to the louvers 239, 239a, and 239b, the blowing duct corresponds to the blowing duct 237, the blowing guide corresponds to the guide surface 237a, the conveying unit corresponds to the returning roller 13, the pressing unit corresponds to the pressing member 14, the driving source corresponds to the returning roller drive motor 20, the first gear corresponds to the first gear 21, the second gear corresponds to the second gear 22, the changeover unit corresponds to the one-way clutches 21a and 22a, the cam corresponds to the cam 24, the first shaft corresponds to the first shaft 19a, the second shaft corresponds to the second shaft 19b, the power transmitting unit corresponds to the timing belt 247, the first driving shaft corresponds to the cam driving shaft 246, the second driving shaft corresponds to the blocking member driving shaft 242, the operation display unit corresponds to the operation display unit 440, and the image forming system corresponds to the system including the sheet post-processing apparatus PD provided with the discharging portion J or the discharging unit JU and the image forming apparatus PR in the present embodiment.
According to the embodiments, it is possible to realize satisfactory stacking property upon discharging a sheet by blowing air, and prevent foreign matters from entering a blowing port.
Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
Number | Date | Country | Kind |
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2012-046726 | Mar 2012 | JP | national |
2012-279960 | Dec 2012 | JP | national |
This application is a divisional of and claims priority under 35 U.S.C. §§120/121 to U.S. patent application Ser. No. 13/782,118, filed on Mar. 1, 2013, which claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2012-046726 filed in Japan on Mar. 2, 2012 and Japanese Patent Application No. 2012-279960 filed in Japan on Dec. 21, 2012. The disclosures of each of the above applications are incorporated herein by reference in their entirety.
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Number | Date | Country | |
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20140203501 A1 | Jul 2014 | US |
Number | Date | Country | |
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Parent | 13782118 | Mar 2013 | US |
Child | 14222984 | US |