Patent Application
20080211177
1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a multi function peripheral, a sheet conveyance apparatus which conveys an image-formed sheet (recording medium), and a sheet processing apparatus which performs processing to the sheet. Particularly the invention relates to the sheet processing apparatus, in which noises and vibration are suppressed, electric power consumption is saved, and productivity is improved by variably controlling a shift moving speed in a horizontal direction according to a shift amount when the sheets are automatically sorted.
2. Description of the Related Art
The sheet processing apparatus included in an image forming apparatus main body performs various kinds of processing. For example, the sheet processing apparatus bundles the plural image-formed sheets discharged from the image forming apparatus main body in each set, and the sheet processing apparatus performs saddle stitch processing to the bundled sheets. The sheet processing apparatus includes a sheet discharge tray which is moved in the horizontal direction parallel to a short side of the sheet while a sheet position is repeatedly shifted. In the sheet discharge tray (hereinafter referred to as shift movement), and the sheets or the processed sheet bundles are automatically sorted while stacked at the positions alternately offset in the horizontal direction.
However, when the shift movement of a large member such as the sheet discharge tray is alternately performed in the horizontal direction, the sheet processing apparatus is enlarged only by placing a drive mechanism of the sheet discharge tray, and the electric power consumption is also increased.
In order to solve the above problem, for example, Japanese Patent Application Laid-Open No. S61-033459 proposes the following sheet sorting device. In the sheet sorting device proposed in Japanese Patent Application Laid-Open No. S61-033459, a sheet-discharge rotating roller is rotated and the sheet is discharged to the sheet discharge tray by rotating frictional force of the sheet-discharge rotating roller, or the sheet bundle to which the saddle stitch processing or the like is performed in the sheet processing apparatus is discharged to the sheet discharge tray. In discharging the sheet, the shift movement is alternately performed in the horizontal direction by moving the rotating roller along with a rotating shaft in the direction of a rotating axial line, i.e., in the direction orthogonal to the sheet discharge direction. Therefore, the sheets or the sheet bundles are stacked on the sheet discharge tray while alternately offset in the horizontal direction.
When the rotating rollers are moved along with the rotating shafts in the axial line direction, it is necessary that the rotating rollers differ from each other in the shift amount according to a size of the sheet. However, in the conventional sheet sorting device, the speeds of the rotating rollers for discharging the sheet are set at a constant value by averaging the speeds at which the rotating rollers are moved along with the rotating shafts to alternately perform the shift movement in the horizontal direction of the rotating axial line. Therefore, there is the following problem to be solved.
In the rotating roller in which the necessary shift movement is small, the electric power consumption cannot be expected. This is because the rotating roller is set at a speed suitable for the large shift amount, even if the operating sound or the vibration of a drive mechanism can be suppressed by reducing the shift speed.
In the rotating roller in which the necessary shift movement is large, the productivity improvement cannot be expected. This is because the rotating roller is set at a speed suitable for the small shift amount, although an operating time can be shortened by increasing shift speed as much as possible to complete the shift.
An object of the invention is to provide an image forming apparatus in which the noises and vibration are suppressed, the electric power consumption is saved, and the productivity is improved by variably controlling the shift moving speed in the horizontal direction according to the shift amount when the sheets are automatically sorted.
Another purpose of the present invention is to provide a sheet conveyance apparatus of the invention includes a sheet conveyance unit which conveys a sheet while nipping the sheet; a moving unit which moves the sheet conveyance unit nipping the sheet toward a direction intersecting with a sheet conveyance direction; and a controller which controls the movement of the moving unit, wherein the controller controls a moving speed of the moving unit according to a predetermined moving amount of the moving unit.
Another purpose of the present invention is to provide a sheet processing apparatus of the invention performs processing to the sheet conveyed by the sheet conveyance apparatus.
Further purpose of the present invention is to provide an image forming apparatus of the invention includes an image forming part which forms an image on a sheet; a sheet conveyance apparatus of the invention which conveys the image-formed sheet; and a sheet processing apparatus which performs processing to the sheet conveyed by the sheet conveyance apparatus. According to the sheet conveyance apparatus of the invention, the moving speed is changed according to the moving amount of the sheet discharged from the image forming apparatus main body when the sheet is moved by the moving unit. That is, when the moving amount is set at a small value, the control is performed such that the moving speed of the moving unit is set at a low speed. Therefore, the generation of the noise and vibration can be suppressed to save the electric power consumption. When the moving amount is set at a large value, the operation time associated with the movement is shortened to eliminate waste of time by increasing the moving speed of the moving unit.
According to the image forming apparatus of the invention, when the moving amount is set at a large value in the moving unit, the moving speed is increased, so that high-speed processing can be performed to enhance the productivity as a whole.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Preferred embodiments of a sheet conveyance apparatus, a sheet processing apparatus, and an image forming apparatus according to the invention will be described in detail with reference to the accompanying drawings.
(Image Forming Apparatus)
As shown in
The image forming apparatus main body 300 is provided with a control device 930 which is of a controller for controlling the whole apparatus, and the control device 930 outputs a control signal or an operation instruction signal to operate each unit and each device.
When the control device 930 outputs the signal for giving an instruction to supply the sheet P, the supply of the sheet P is started from the sheet cassette 910 or 911 or the deck 913. An original D on the original setting plate 906 is irradiated with light emitted from the light source 907, and the photosensitive drum 914 is irradiated through the lens system 908 with the light reflected from the original D. The photosensitive drum 914 is previously charged by the primary charging device 919, and an electrostatic latent image is formed on the photosensitive drum 914 by the light irradiation. Then, the electrostatic latent image is developed to form a toner image with the development device 915.
In the sheet P supplied from the sheet supply unit 909, skew movement is corrected by a registration roller 901. Then, the sheet P is delivered to the image forming part 902 at predetermined timing. In the image forming part 902, the toner image on the photosensitive drum 914 is transferred to the sheet P by the transferring charging device 916, the separation charging device 917 charges the toner-image-transferred sheet P in a polarity opposite to the transferring charging device 916, and thereby the toner-image-transferred sheet P is separated from the photosensitive drum 914. The conveyance device 920 conveys the separated sheet P to the fixing device 904, and the fixing device 904 permanently fixes the transferred image onto the sheet P. The image-fixed sheet P is discharged from the image forming apparatus main body 300 by a discharge roller pair 399 in a straight sheet-discharge mode in which the image surface is orientated upward. Alternatively, the image-fixed sheet P is conveyed to a sheet reverse path after the image is fixed, and the image-fixed sheet P is discharged from the image forming apparatus main body 300 by a discharge roller pair 399 in a reverse sheet-discharge mode in which the image surface is orientated downward by the reversal. Thus, the image is formed on the sheet P supplied from the sheet supply unit 909, and the sheet P is discharged toward the sheet conveyance apparatus 100. Then, a configuration of the sheet conveyance apparatus 100 will be described.
(Sheet Conveyance Apparatus)
As shown in
As used herein, “deviation (shift) in the traverse direction” shall means that the sheet P discharged from the image forming apparatus main body 300 is delivered which shifted toward the direction orthogonal to the sheet-discharge direction with respect to the sheet conveyance apparatus 100.
The traverse direction deviation detection sensor 104 always monitors the deviation in the traverse direction of the sheet P delivered from the image forming apparatus main body 300, and the traverse direction deviation detection sensor 104 transmits detection result as shift information to the control device 930. The control device 930 determined whether the amount of deviation in the traverse direction is added or subtracted according to the shift direction with respect to the reference, and the control device 930 computes how much a shift moving unit (moving unit) 108 is totally shifted from a home position (initial position) in order that the sheet P is aligned based on the sheet center line along the sheet conveyance direction. Then, the control device 930 outputs the operation signal. In the embodiment, the control device 930 which controls the whole apparatus controls both the image forming apparatus main body 300 and the sheet conveyance apparatus 100. However, in the configuration where the sheet conveyance apparatus 100 includes a finisher control unit 501 (see
A configuration and an operating mode of the shift moving unit 108 which is of the moving unit will be described below with reference to
The image-formed sheet P is discharged from the image forming apparatus main body 300, the sheet P is delivered to the conveyance path 103 of the sheet conveyance apparatus 100, and the sheet P is conveyed through the conveyance path 103. Then, the sheet P is delivered to the shift moving unit 108. The shift moving unit 108 includes a sheet conveyance motor 208, and the sheet conveyance motor 208 starts the drive by the operation signal outputted by the delivery of the sheet P to the sheet conveyance motor 208. The outputted motor revolving power is transmitted to a drive belt 209 to rotate a sheet conveyance roller 206. A sheet conveyance roller 207 is also rotated by the motor revolving power transmitted to the drive belt 213, and the sheet P is conveyed along the sheet conveyance direction shown by an arrow C in
The whole of the shift moving unit 108 is guided by a pair of parallel slide rails 106 and 107 fixed to the sheet conveyance apparatus 100, and the shift moving unit 108 is reciprocally moved in the shift direction of the arrow D orthogonal to the sheet conveyance direction C through slide bushings 205a to 205d. The control device 930 outputs and sends a drive-on signal to the shift drive motor 210, and the control device 930 causes the drive belt 211 to run by the motor revolving power. The shift moving unit 108 slides on the slide rails 106 and 107 in the direction of the arrow D through a transmission plate 212 which is anchored and fixed to the drive belt 211. While the sheet P is conveyed toward the direction of the arrow C by the shift movement of the shift moving unit 108 with the sheet P nipped by the sheet conveyance rollers 206 and 207, the position correction is performed to the sheet P by the error amount X caused by the deviation in the traverse direction, and the sheet P is aligned on the center line of the conveyance path 103. For example, as shown in
At this point, while the position of the sheet P is corrected in the direction of the arrow D by the shift movement, the sheet P is securely nipped by the pair of sheet conveyance rollers 206 and 207 which is of the sheet conveyance unit, and the sheet P is conveyed toward the sheet conveyance direction C. According to the above configuration, the sheet skew is not generated even when the sheet P has a large size such as A3 size. That is, when a front end portion or a rear end portion of the large-size sheet P reaches a curved point of the conveyance path 103, the sheet P is firmly nipped by the two sheet conveyance rollers 206 and 207, which overcomes moment generated by slide resistance. As a result, the sheet skew movement caused by the generation of slip between the sheet and the sheet conveyance rollers 206 and 207 is never generated during the shift movement, so that the sheet P can stably be conveyed while the shift movement is performed.
In the non-shift mode (center discharge sheet) of
Z1=X×(−1) (1)
When the shift moving unit 108 is moved by the necessary shift amount Z1, the sheet P is conveyed on the center line of the conveyance path 103 and, for example, the sheet P can be discharged to “center position” of the upper tray 136. The reference symbol P′ in
In the front-shift mode (front-shift sheet discharge), the shift moving unit 108 is moved to the position where the shift moving unit 108 is separated away from the home position by “Y”.
Z2=Y−X (2)
When the shift moving unit 108 is moved by the necessary shift amount Z2, the position of the sheet P is corrected to the position where the sheet P is moved by “Y” toward the front side of the sheet conveyance apparatus and, for example, the sheet P can be stacked while offset from the center position of the upper tray 136 toward the front side of the sheet conveyance apparatus (see the reference symbol P′ in
In the rear-shift mode (rear-shift sheet discharge), the sheet P discharged from the image forming apparatus main body 300 is delivered while shifted toward the rear side from the center position of the sheet conveyance apparatus 100 by the error amount “X” caused by the deviation in the traverse direction. The traverse direction deviation detection sensor 104 detects the amount of deviation X of the sheet P, the control device 930 performs the computation based on the detection signal of the traverse direction deviation detection sensor 104, and the control device 930 computes a necessary shift amount Z3 by which the shift moving unit 108 should be moved from the following formula (3).
Z3=Y+X (3)
When the shift moving unit 108 is moved by the necessary shift amount Z3, the position of the sheet P is corrected to the position where the sheet P is moved by “Y” toward the rear side of the sheet conveyance apparatus and, for example, the sheet P can be stacked while offset from the center position of the upper tray 136 toward the rear side of the sheet conveyance apparatus (see the reference symbol P′ in
Thus, the control device 930 determines the moving speed of the shift moving unit 108 according to each of the necessary shift amounts Z1, Z2, and Z3 computed from the formulas (1), (2), and (3). When the necessary shift amounts Z1, Z2, and Z3 are small, the control device 930 moves the shift moving unit 108 at low speed.
The maximum shift amount of the shift moving unit 108 is defined as Zmax. For example, the shift amount range is divided by Zmax/2 so as to correspond to the center line position, which is of the center in the crosswise direction of the sheet, along the sheet moving direction. The moving speed of the shift moving unit 108 is set at V1 in the shift amount range of 0 to Zmax/2, and the moving speed of the shift moving unit 108 is set at V2 in the shift amount range of Zmax/2 to Zmax. In this case, the moving speed of the shift moving unit 108 is set to V1<V2 such that the moving speed is reduced when the shift amount is small.
However, it is not always necessary that the shift amount range of the sheet be divided at the center in the crosswise direction of the sheet. That is, it is not always necessary that the shift amount range be divided by the Zmax/2. The shift amount range may arbitrarily be determined according to apparatus specifications. In the embodiment, the shift amount range is divided into the two ranges. The division of the shift amount range is not limited to the two ranges, but the shift amount range may be divided into at least three ranges.
Thus, the control device 930 variably controls the shift moving speed of the shift moving unit 108 according to the shift amount. That is, when the necessary shift movement is small, the control device 930 moves the shift moving unit 108 at low speed. Therefore, the noise and vibration generated from the shift drive motor 210 constituting the drive system of the shift moving unit 108 can be decreased to the minimum. The low-speed movement also saves the electric power consumption. On the contrary, when the necessary shift movement is large, the shift moving speed of the shift moving unit 108 is increased to end the movement as fast as possible. Therefore, the operating time can be shortened to contribute to the total productivity improvement in the image forming apparatus main body 300. However, even in this case, the control device 930 can perform the control through the finisher control unit 501 incorporated into the sheet conveyance apparatus 100.
As shown in a flowchart of
Referring to the flowchart of
At this point, in order to shorten a distance between the sheet conveyance roller 107 and the second buffer roller pair 115 (in this case, the roller pair does not separate), the conveyance speed is reduced to a predetermined speed before the sheet is shifted in the case of the large size (Step S4). This control enables the path length, where the sheet P is not nipped, to be shortened to perform the shift movement of the sheet P except for the sheet conveyance rollers 206 and 207. The shift moving unit 108 starts the shift processing for the sheet P in the conveyance path 103 according to the already set mode such as the shift mode and the non-shift mode (Step S3).
When the front-shift mode or the rear-shift mode is selected, the predetermined shift amount is determined. The control device 930 computes the moving amount (actual shift amount) of the shift moving unit 108 while the error amount X, which is detected by the traverse direction deviation detection sensor 104 and caused by the deviation in the traverse direction of the sheet P, is added to or subtracted from the predetermined shift amount (Step S5).
When the non-shift mode is selected, because the shift amount is 0 (zero), the control device 930 computes the moving amount (actual shift amount) of the shift moving unit 108 only with the error amount X which is detected by the traverse direction deviation detection sensor 104 and caused by the deviation in the traverse direction of the sheet P (Step S6). Thus, the control device 930 determines the moving speed of the shift moving unit 108 according to the moving amount. That is, the control device 930 shifts shift moving unit 108 at low moving speed when the moving amount is small, and the control device 930 shifts the shift moving unit 108 at high moving speed when the moving amount is large (Step S7).
After the shift moving unit 108 is shifted, when the sheet P is the large size (Step S8), the conveyance speed which is reduced before the shift is returned to the normal speed (Step S10). Finally, the traverse direction deviation detection sensor 104 and the shift moving unit 108 are returned to the home position (center position), and a sequence of operations is ended (Step S9). Then, the flow returns to the start of the sequence, and the same operations are repeated for the necessary number.
In the sheet conveyance apparatus 100 which is of the sheet processing apparatus, the sheet processing such as staple processing and saddle stitch processing is performed as follows. First a configuration of a finisher control unit 501 which controls the conveyance drive and post-processing of the sheet conveyance apparatus 100 will schematically be described with reference to a functional block diagram of
The finisher control unit 501 has a CPU circuit part 510 including a CPU 511, a ROM 512, and a RAM 513. The CPU circuit part 510 performs data exchange by communicating with a CPU circuit part 150 provided on the image forming apparatus main body side through a communication IC 514, the CPU circuit part 510 executes various programs stored in the ROM 512 to perform the drive control of the sheet conveyance apparatus 100 based on the instruction from the CPU circuit part 150. In performing the drive control, the CPU circuit part 150 captures the detection signals from various sensors. The various sensors include the transverse direction deviation detection sensor 104. A driver 520 is connected to the CPU circuit part 510, and the driver 520 drives the motor and the solenoid based on the signal from the CPU circuit part 510. The motor includes the shift conveyance motor 208 which is of the drive source of the shift roller pair 107 and the shift motor 210 which is of the drive source of the shift unit 108. The shift conveyance motor 208 and the shift motor 210 are formed by a stepping motor. In the shift conveyance motor 208 and the shift motor 210, the roller pair driven by each motor is rotated at constant speed or at unique speed by controlling a magnetic excitation pulse rate. The shift motor can be driven in normal and reverse rotating directions by the driver 520.
Referring to
In the sheet conveyance apparatus 100 which is of the sheet processing apparatus, a saddle unit 135 which is of the processing unit performs the saddle stitch processing to the sheet P. In this case, a saddle path switch flapper 125 is operated to the position shown by the broken line by the drive unit such as the solenoid, which allows the sheet P to be conveyed to a saddle path 133. Then, the sheet P is guided to the saddle unit 135 which is of the processing unit by a saddle entrance roller pair 134, and the saddle stitch processing is performed.
On the other hand, when the sheet P is discharged to the lower tray 137, the following operations are performed. The sheet P conveyed by the conveyance roller pair 124 is conveyed to a lower path 126 by the saddle path switch flapper 125. Then, the sheet P is discharged to a processing tray 129 by a lower discharge roller pair 132, and alignment processing is performed to each predetermined number of sheets on the processing tray 129 by a returning member including a paddle 131 and a roulette belt 128. Then, binding processing is performed if needed by a stapler 138 which is of the processing unit, the bundle of sheets P is discharged to the lower tray 137 by a bundle sheet discharge roller pair 130.
Usually it takes a predetermined time longer than a sheet interval to perform the staple processing or the saddle stitch processing. Therefore, so-called sheet buffer processing will be described below. The sheet buffer processing is one in which the sheet processing is performed without stopping the image formation in the image forming part 902.
When another sheet P is further overlaid on the sheets S1 and S2, the drive of the second buffer roller pair 115 is continued until the rear-end positions of the sheets S1 and S2 reach the point A. Then, the above-described processing is repeated to perform the overlaying processing of another sheet P. After the overlaying processing is performed to the predetermined number of sheets P, the sheet bundle is conveyed to the processing unit or the saddle unit by the third buffer roller pair 122 and the conveyance roller pair 124.
Although the reversal type buffer unit is described in the embodiment, the invention is not limited to the reversal type buffer unit. However, the same effect can also be obtained by a rotary buffer unit or the buffer units of other types. Because the buffer unit is not always included in the sheet processing apparatus of the invention, there is no problem when the sheet processing apparatus is not provided with the buffer unit.
As shown in
The embodiments in the image forming apparatus, the sheet conveyance apparatus, and the sheet processing apparatus of the invention are described above. However, the invention is not limited to the above embodiments, but other embodiments, applications, modifications and combinations thereof could be made without departing from the scope and spirit of the invention.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2005-251423, filed Aug. 31, 2005, and Japanese Patent Application No. 2006-176452, filed Jun. 27, 2006, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-251423 | Aug 2005 | JP | national |
| 2006-176452 | Jun 2006 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11466704 | Aug 2006 | US |
| Child | 12107376 | US |
