JP5247052B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding apparatus that feeds sheets one by one from a stacked sheet, and an image forming apparatus including the sheet feeding apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, in order to transfer a toner image formed on a photoconductor onto a sheet at a transfer position, a sheet cut to a predetermined size is transferred to the transfer position. A sheet feeding device for feeding sheets one by one is provided.

  As this sheet feeding apparatus, a configuration is disclosed in which air is blown by a fan from one end side in the conveyance direction of the sheets stacked in the storage box to float the sheet, and the floated sheet is sucked to the conveyance belt and conveyed. (See Patent Document 1).

  However, the flying height of the sheet varies depending on the material (thickness and weight). In view of this, a configuration has been proposed in which the raising and lowering of the sheet table on which the sheets are stacked is controlled so that the floating position of the sheet floated by the air blowing is positioned within a predetermined range. For example, it is determined by position detection means whether or not the floating position of the floated sheet is within a predetermined range, and when it is out of the predetermined range, the sheet table is moved up and down so that the floated sheet is predetermined. The structure controlled so that it may be located in the range is disclosed (refer patent document 2).

  Alternatively, a configuration has been proposed in which the rotation speed of the rolling fan is controlled so that the sheet has an optimum flying height regardless of the material. In other words, if the seat is thin or light, the fan speed is controlled to be low (slow), and if the sheet is thick or heavy, the fan is controlled to be high (fast). To do. Specifically, for example, a distance measurement sensor recognizes the distance from the belt surface of the conveyor belt to the sheet that is levitated, and based on this, the rotation speed of the fan is controlled in order to control the amount of air blown. A configuration is disclosed (see Patent Document 3).

  Also, by inputting the material (thickness and weight) of the sheets stacked on the sheet table from the operation unit of the image forming apparatus, the amount of air spraying is uniquely determined according to the input material of the sheet. Some have been proposed to control.

JP-A-7-196187 JP-A-2005-272019 JP-A-7-89625

  However, in the technique described in Patent Document 2, even if the material (thickness and weight) of the sheet is different, the sheet is positioned within a predetermined range by raising and lowering the sheet base, but the sheet within the predetermined range It is not possible to determine whether or not is in an optimal whispering state. Here, every time the material (thickness or weight) of the sheets stacked on the sheet table is changed, as disclosed in Patent Document 3, in order to make the sheet to be optimally rolled regardless of the material, It is conceivable to change the rotational speed of the fan. However, even if the rotation speed is set to make the appropriate air blowing amount for each material of the sheet, the blower fan is not suitable due to variations in the fan itself, changes in fan characteristics over time, or voltage drop due to bundled wires. May not be obtained stably. In this case, for example, when the sheet is thin or light material, the rotation speed of the rolling fan rotates faster than the target, the sheet rolling state is not stable, jam, skew, misalignment, scratch, breakage In some cases, problems such as dirt may occur. Also, if the sheet is thick or heavy, the rotation speed of the fan will rotate slower than the target, and appropriate air will not flow between the sheets, causing problems such as double sheet feeding. There is.

  In the configuration in which the sheet material (thickness and weight) is input from the operation unit of the image forming apparatus, the sheet material (thickness and weight) input from the operation unit and the material of the sheet actually loaded on the sheet table May be different. In this case, the rotation speed of the rolling fan becomes an inappropriate value, and as described above, problems such as sheet double feeding, skew feeding, misalignment, scratches, breakage, and dirt may occur.

  Therefore, an object of the present invention is to stabilize the sheet-rolling state by blowing air regardless of variations in the fan itself or changes in characteristics over time.

In order to achieve the above object, a typical configuration of the present invention includes a tray provided to be capable of supporting a plurality of sheets, and air for spreading the sheets toward an end portion of the sheet supported by the tray. an air blowing portion for blowing, the sheet presence detecting means for detecting the presence or absence of a sheet on the tray, provided with, when it is detected that there is no sheet on the tray by the sheet presence detecting means, blowing the air The amount of air blown from the air blowing section is adjusted after the tray is lowered until it is no longer in front of the position where the air is blown from the section.

According to the present invention, by adjusting the amount of air blown from the air blowing unit, it is possible to stabilize the sheet-rolling state regardless of performance variations or changes with time. Further, by limiting the adjustment operation of the air blowing amount when there is no sheet on the tray, the air blowing amount can be more reliably adjusted.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

(Description of image forming apparatus)
First, a schematic configuration of the image forming apparatus shown in FIG. 1 will be described. FIG. 1 is a schematic cross-sectional view illustrating a schematic configuration of an image forming apparatus having a sheet feeding device.

  In FIG. 1, reference numeral 1 denotes an image forming apparatus. The image forming apparatus 1 includes a printer main body 1000 and a scanner 2000 disposed on the upper surface of the printer main body 1000. Further, the image forming apparatus 1 includes a sheet feeding device 3000 that feeds sheets to the printer main body 1000. The sheet feeding device 3000 includes an air separation and feeding mechanism as a sheet separation and feeding unit in order to perform stable separation and feeding for various types of sheets. The sheet feeding device 3000 will be described in detail later.

  First, the image forming apparatus 1 will be described in detail. Here, the scanner 2000 that reads a document includes a scanning optical system light source 201, a platen glass 202, a document pressure plate 203 that opens and closes, a lens 204, a light receiving element (photoelectric conversion) 205, an image processing unit 206, a memory unit 208, and the like. . The memory unit 208 is for storing the image processing signal processed by the image processing unit 206.

  When the original is read, the original placed on the platen glass 202 is read by irradiating light with the scanning optical system light source 201. Then, the read document image is processed by the image processing unit 206, converted into an electrically encoded electric signal 207, and transmitted to the laser scanner 111 as an image forming unit. Note that the image information processed and encoded by the image processing unit 206 may be temporarily stored in the memory unit 208 and transmitted to the laser scanner 111 as necessary by a signal from the control unit 130.

  The printer main body 1000 includes a sheet conveying unit 1004 that conveys a sheet fed by the sheet feeding device 3000 to the image forming unit 1005, a control unit 130 for controlling the printer 1000, and the like.

  The sheet conveying unit 1004 includes a registration roller unit having a pre-registration roller pair 122 and a registration roller pair 123. The sheet fed from the sheet feeding device 3000 is guided by a sheet conveying path 121 constituted by a guide plate, and after passing through the pre-registration roller pair 122, is guided to the registration roller pair 123. Thereafter, the sheet is once abutted against the registration roller pair 123, and the skew that occurs during sheet feeding and conveyance is corrected, and then conveyed to the image forming unit 1005.

  The image forming unit 1005 includes a photosensitive drum 112, a laser scanner 111, a developing device 114, a transfer charger 115, a separation charger 116, and the like. At the time of image formation, the laser beam from the laser scanner 111 is folded back by the mirror 113 and applied to the exposure position 112a on the photosensitive drum 112 that rotates in the clockwise direction in FIG. As a result, a latent image is formed on the photosensitive drum 112. Thereafter, the latent image formed on the photosensitive drum 112 is visualized as a toner image by the developing device 114. It is possible to change the irradiation position of the laser beam through a laser writing position control circuit by a control signal from the control unit 130, and form a latent image in the longitudinal direction on the photosensitive drum 112, that is, a so-called main scanning direction. The position can be changed.

  The toner image on the photosensitive drum 112 is transferred to a sheet by the transfer charger 115 in the transfer unit 112b. Further, the sheet on which the toner image is transferred is electrostatically separated from the photosensitive drum 112 by the separation charger 116 and is conveyed to the fixing device 118 by the conveyance belt 117 to fix the toner image. The sheet on which the toner image is fixed is discharged out of the apparatus by a discharge roller 119. In addition, a discharge sensor 120 is provided in the conveyance path between the fixing device 118 and the discharge roller 119 so that passage of the sheet there can be detected.

  In this embodiment, the printer main body 1000 and the scanner 2000 are separate from each other, but the printer main body 1000 and the scanner 2000 may be integrated. The printer main body 1000 functions as a copying machine when a processing signal of the scanner 2000 is input to the laser scanner 111, and functions as a FAX when a FAX transmission signal is input. Furthermore, if an output signal of a personal computer is input, it functions as a printer.

  Conversely, if the processing signal of the image processing unit 206 of the scanner 2000 is transmitted to another FAX, it functions as a FAX. Further, in the scanner 2000, if an automatic document feeder 250 as shown by a two-dot chain line is installed instead of the pressure plate 203, the document can be automatically read.

(Description of sheet feeding device)
Next, the sheet feeding device 3000 in the image forming apparatus 1 shown in FIG. 1 will be described.

  The sheet feeding device 3000 includes a sheet feeding unit 331 on the lower side and a sheet feeding unit 322 on the upper side. Each of the sheet feeding units 331 and 332 includes sheet storage units 301 and 311 that can store a plurality of sheets S, respectively. In each of the sheet storage portions 301 and 311, trays 302 and 312 provided so as to support the stored sheet S, and a rear end that regulates a rear end of the sheet S in the conveyance direction (the direction of arrow A in FIG. 2). Each of the regulation plates 303 is provided. The trays 302 and 312 are provided so that they can be raised and lowered. The trailing edge regulating plate 303 is movable according to the size in the conveying direction of the sheet S, and regulates the trailing edge in the conveying direction of the sheet so that the leading edge in the conveying direction of the sheet is aligned with the leading edge side in the conveying direction of the sheet storage unit 302. doing. The sheet feeding units 331 and 332 have the same configuration, but the rear end regulating plate on the sheet feeding unit 332 side is not illustrated.

  Here, with reference to FIG. 2, a sheet separation and feeding unit (air separation and feeding mechanism) in the sheet feeding apparatus will be described. FIG. 2 is an enlarged view of a main part showing a sheet separating and feeding unit in the sheet feeding apparatus shown in FIG.

  In the sheet separating and feeding unit 304, a sheet fan in the sheet storage unit 301 is rotated by a whirling fan F151 as a pre-feeding operation, and air is blown from a whirling nozzle 151 that is an air blowing unit. Start whispering. When a feeding start signal is transmitted from the controller 300, a negative pressure (suction force) is generated in the suction belt 305 by the suction fan F150, and the suction of the sheet is started. After a predetermined suction time from the start of suction, only the topmost sheet S1 of the stacked sheets S is sucked to the suction belt 305. After a predetermined time, rotation of the suction belt 305 is started by the suction belt motor M102 with the sheet S1 being sucked, and the sheet S1 is conveyed in the direction of arrow A. When the leading edge of the sheet reaches the belt pulley portion, the leading edge of the sheet is released from the suction force by the suction fan F150 and is separated from the suction belt 305 and transferred to the drawing roller pair 10. FIG. 2 illustrates a configuration in which a blower fan F152 that blows air from the separation nozzle 152 for separating the leading end of the sheet from the suction belt 305 is illustrated. When the leading edge of the sheet S1 reaches the drawing roller pair 10, the negative pressure by the suction fan F150 is released, so that the sheet is released from the suction force to the suction belt 305 and is transported only by the transport force of the pulling roller pair 10. . When the feeding start signal is transmitted again from the control unit 300 after the trailing edge of the sheet comes out of the suction belt portion, the feeding operation is started, and the subsequent sheet S2 is separated and fed.

  Here, as a pre-feeding operation, the fan F151 is operated before the feeding start signal is transmitted. However, after the feeding start signal is transmitted, the fan F151 is controlled to operate. It doesn't matter.

  Although only the sheet separation / feed unit 304 on the sheet storage unit 301 side has been described here, a sheet separation / feed unit 314 is similarly provided on the sheet storage unit 311 side, and the same separation / feed is performed. Is called.

  Further, as shown in FIG. 3, the drawing motors M10 and M20 are connected to the drawing roller pairs 10 and 20, respectively. Corresponding transport motors M11, M12, M13, M14, M15, M16, M21, M22, and M23 are connected to the transport roller pairs 11, 12, 13, 14, 15, 16, 21, 22, and 23, respectively. Yes. The sheet feeding device can drive each roller pair independently.

  In FIG. 3, reference numerals M5 and M205 denote lifter motors as lifter driving means for raising and lowering the trays 302 and 312, and moving the trays 302 and 312 in the sheet feeding units 331 and 332 up and down. M102 and M202 are suction belt motors for rotationally driving the suction belts 305 and 315 in the sheet feeding units 331 and 332, respectively. F150 and F250 are suction fans for sucking sheets to the belts 305 and 315 in the sheet feeding units 331 and 332, respectively. F151 and F251 are sheet rolling fans in the sheet feeding units 331 and 332, respectively. F152 and F252 are rolling fans in the sheet feeding units 331 and 332, respectively. The operation of these operation units is controlled by the control unit 300 as control means.

  In FIG. 3, reference numeral 604 denotes a rotation speed detection sensor as a rotation speed detection means, which detects the rotation speeds of the fan F151 and F251. Reference numeral 605 denotes a tray lower position detection sensor serving as a lower position detecting unit, which detects the lower position of the tray. This lower position is a position where the trays 302 and 312 are lowered to the maximum during normal operation. Reference numeral 606 denotes a sheet presence / absence detection sensor serving as a sheet presence / absence detection unit, which detects the presence / absence of sheets stacked on the trays 302 and 312. Reference numeral 607 denotes a sheet floating lower limit sensor, and reference numeral 608 denotes a sheet floating upper limit sensor, which is a sensor for detecting the position of the sheet floating with the air from the rolling fan F151. A sheet loading position detection sensor 609 is provided in the middle of the raising / lowering range of the tray and stops at a position higher than the lower position. And based on the information from these various sensors, the control part 300 controls operation | movement of each operation | movement part mentioned above.

  Note that sheet information such as the paper size, paper type, and basis weight of the sheets stored in the respective sheet storage units 301 and 311 can be set from the operation unit of the image forming apparatus.

(Explanation of control block)
FIG. 4 is a block diagram showing the configuration of the control unit 130 in the printer main body 1000 and the control unit 300 of the sheet feeding apparatus 3000 shown in FIG.

  The control unit 130 in the printer main body 1000 includes a CPU 211, ROM 212, RAM 213, communication interface (I / F) 214, input / output port 215, operation unit 216, image processing unit 206, and image memory unit 208.

  The CPU 211 performs basic control of the printer main body 1000, and a ROM 212 in which a control program is written, a work RAM 213 for performing processing, and an input / output port 215 are connected by an address bus and a data bus. A part of the RAM 213 is a backup RAM in which data is not erased even when the power is turned off. The input / output port 215 is connected to various load devices such as a motor and a clutch controlled by the printer main body 1000 and an input device such as a sensor for detecting the position of the sheet.

  The CPU 211 sequentially performs input / output control via the input / output port 215 in accordance with the contents of the control program stored in the ROM 212, and executes image forming processing. An operation unit 216 is connected to the CPU 211, and the CPU 211 controls a display unit and a key input unit of the operation unit 216. The user instructs the CPU 211 to switch the image forming operation mode and display through the key input unit. The CPU 211 operates the display unit of the operation unit 216 with respect to the operation state of the printer main body 1000 and the operation mode set by key input. Is displayed. Further, an image processing unit 206 that processes a signal converted into an electric signal by the image sensor unit (light receiving element) 205 and an image memory unit 208 that stores the processed image are connected to the CPU 211.

  Note that the control unit 300 of the sheet feeding device 3000 performs the operation described with reference to FIG. 1, the CPU 351, the ROM 352, the RAM 353, the communication interface (I / F) 354, the input / output port 355, and the operation unit 356. It consists of The CPU 351 is connected via an input / output port 355 from a floating upper limit sensor 608 and a floating lower limit sensor 607, which are described later, a rotation speed detection sensor 604, a tray lower position detection sensor 605, a sheet presence / absence detection sensor 606, and a sheet loading position detection sensor 609. Enter the detection result. Based on the detection result, the CPU 351 outputs a drive command to lifter motors M5 and M205, firing fans F151 and F251, and suction fans F150 and F250, which will be described later. Note that the levitation upper limit sensor 608 is disposed above the levitation lower limit sensor 607. Further, a distance measuring sensor (not shown) capable of measuring a distance may be used instead of the ascent upper limit sensor and the ascent lower limit sensor.

(Explanation of operation unit)
FIG. 5 is a schematic diagram showing the configuration of the operation unit in the image forming apparatus of the present embodiment.

  In FIG. 5, reference numeral 221 denotes a display unit, which displays various messages such as the operating state of the apparatus and work instructions to the user, work procedures, and the like. Further, the surface of the display unit 221 is configured by a touch panel, and acts as a selection key by touching the surface. Reference numeral 222 denotes a numeric keypad for inputting numbers. Reference numeral 223 denotes a start key. When this key is pressed, a copying operation is started. Reference numeral 224 denotes an application mode selection key for inputting sheet conditions such as sheet surface material, basis weight, and surface smoothness.

  For example, the material of the sheet accommodated in the sheet feeding apparatus 3000 is selected from the display unit (operation screen) 225 as shown in FIG. Here, thin paper 231, plain paper 232, thick paper 233, and thickest opening 234 are illustrated as specific materials of the sheet. Further, the material may be automatically set (235 in the figure). Further, the sheet conditions such as the sheet surface material, basis weight, and surface smoothness may be finely set (236 in the figure).

  The control unit 300 of the sheet feeding device 3000 sets the rotation speed of the blowing fans F151 and F251 according to the setting of the sheet material (basis weight, surface property, etc.) set in the display unit 225 shown in FIG. A table is provided for changing the rotational speed to obtain the rotational speed. When the setting is not made, the normal plain paper 232 is set. Further, other than the setting items on the display unit shown in FIG.

(Explanation of sheet separation and feeding section)
Next, the configuration of the sheet separating / feeding unit (air separating / feeding mechanism) included in the above-described sheet feeding unit will be described.

  FIG. 7 is a cross-sectional configuration diagram of the peripheral portion of the sheet separating and feeding unit and the sheet storage unit in the sheet feeding unit. 2 illustrates a configuration in which the suction fan F150 is disposed in the suction belt 305, but the suction fan F150 may be disposed outside the suction belt 305 as illustrated in FIG.

  7 illustrates the sheet separating and feeding unit 304 of the sheet feeding unit 331 in the sheet feeding device 3000 illustrated in FIG. 1, but the sheet feeding unit 332 in the sheet feeding device 3000 has the same configuration. It is.

  In FIG. 7, the tray 302 that lifts and lowers the sheet bundle on which the sheets S are stacked can be moved up and down by driving a lifter motor M <b> 5 via a pulley 603. An encoder is attached to the lifter motor M5, and it is possible to know the drive amount of the lifter motor M5, that is, the movement amount of the tray 302 by this encoder. The moving direction of the tray 302 can be known from the rotation direction of the encoder or the control signal of the motor.

  In order to detect the lower position of the tray 302, a tray lower position detection sensor 605 is disposed. On the other hand, a sheet presence / absence detection sensor 606, a sheet floating lower limit sensor 607, and a sheet floating upper limit sensor 608 for detecting the height of the sheet are disposed above the sheet separating and feeding unit 304. The sheet presence / absence detection sensor 606 detects a sheet with a flag sensor, and the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608 detect a sheet with an optical sensor. The sheet presence / absence detection sensor 606 is disposed below the sheet lift lower limit sensor 607 and the sheet lift upper limit sensor 608. That is, when the sheet S stacked on the tray 302 rises to the feeding start position, the sheet presence / absence detection sensor 606 moves the upper surface of the sheet bundle S before the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608. It is configured so that it can be detected.

  Further, the sheet lift lower limit sensor 607 and the sheet lift upper limit sensor 608 are sensors for detecting the position of the sheet lifted by the air from the separation fan F151 described later. The sensitivity of the sheet floating lower limit sensor 607 is adjusted so that a floating sheet positioned below the sheet floating upper limit sensor 608 can be detected. As a result, it is possible to detect whether the floated sheet is positioned within a predetermined range using the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608. The relationship between the detection state of the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608 and the sheet feeding state will be described later.

  Further, a fan F151 and a fan fan duct 610 are installed for the purpose of rolling the sheet S stored in the sheet storage unit 301 prior to the feeding operation. By supplying the wind pressure in the discharge direction (the amount of air blown) generated by rotating the fan F151 to the vicinity of the uppermost sheet of the sheet bundle S by the fan fan duct 610, a plurality of sheets are supplied during the sheet feeding operation. Is prevented from being fed at once (double feed).

  Further, a suction belt 305, a suction fan F150, and a suction fan duct 613 are installed as a sheet feeding mechanism. The wind pressure in the suction direction generated by rotating the suction fan F150 is applied to the suction belt 305 through the suction fan duct 613 so that the uppermost sheet of the sheet bundle S is sucked. The sheet adsorbed on the adsorption belt 305 is conveyed to the feeding sensor 620 and the drawing roller pair 10 side by rotating the adsorption belt 305 in the direction shown in the drawing.

  FIG. 7 shows a state where the sheet is sucked by the suction fan F150. When the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608 detect the sheet floating position, the sheet floating position is detected while the rolling fan F151 is operated. That is, as shown in FIG. 9, the raising / lowering of the tray 302 is controlled based on the sheet lift lower limit sensor 607 and the sheet lift upper limit sensor 608 while the suction fan F151 is operated without operating the suction fan F150. The Note that the standby position of the sheet bundle S when both the suction fan F150 and the separation fan F151 are in the non-operating state may be the on-edge (detection position) of the sheet lifting lower limit sensor 607, or may be the on-edge of the sheet presence / absence detection sensor 606. Absent.

  In FIG. 7, the presence / absence of a sheet on the tray 302 is detected by the sheet presence / absence detection sensor 606, but the on-edge (a dotted line position in FIG. 7) of the sheet presence / absence detection sensor 606 is an air blowing portion of the fan duct 610. It is arranged below the firing nozzle 151. Further, when the separation fan F151 is not in operation, the stop position (standby position) of the tray 302 is the on-edge of the sheet presence / absence detection sensor 606. A sheet loading position detection sensor 609 is disposed in the middle of the raising / lowering range of the tray 302. The sheet loading position detection sensor 609 outputs a signal for detecting and stopping the tray 302 while the tray 302 is lowered and moved to the lower position when the sheet presence / absence detection sensor 606 detects the absence of a sheet. Is. In this way, the tray 302 is stopped without lowering the tray to the lower position so that the sheet can be loaded, thereby improving the workability of loading the sheet. Further, when sheets for one pack (500 sheets) are loaded on the tray 302, the sheet loading position detection sensor 609 controls the tray 302 to move down until it detects the uppermost surface of the loaded sheet. The top surface position is always constant. As a result, the sheets can always be loaded at the same height, and workability is improved.

  8A and 8B explain the logic of the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608. FIG. If the standby position of the sheet bundle S when both the suction fan F150 and the separation fan F151 are in the non-operating state is the on-edge of the sheet lifting lower limit sensor 607, that state is the standby state of the sheet bundle S. When the fan F151 is driven in this state, several sheets above the sheet bundle S are rolled, the uppermost sheet of the sheet bundle S floats, and the uppermost sheet that floats is between the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608. The raising and lowering of the tray 302 is controlled to enter.

  The sheet detectable lower limits of the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608 are as shown in FIG.

  It should be noted that the wind pressure (air volume) of the fan F 151 is optimal by inputting sheet conditions such as the surface material, basis weight, and surface smoothness of the sheets stacked on the tray 302 from the operation screen 225 shown in FIG. The number of rotations of the fan is set so that the number of rotations is as follows. When the rolling fan F151 operates under the input sheet condition, the uppermost sheet of the sheet bundle S is blown up and moves between the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608, or the sheet floating upper limit sensor 608. Move upwards. As described above, the sheet floating lower limit sensor 607 and the sheet floating upper limit sensor 608 can be used for the floating sheet even if the raising and lowering operation of the tray 302 is not performed when the rolling fan F151 operates at an optimum rotation speed corresponding to the material of the sheet. It is arrange | positioned in the position which can detect. As shown in FIG. 11, when the sheet condition set on the operation screen matches the sheet condition stacked on the tray 302, the tray 302 is finally controlled to be lowered by ΔL1.

(Adjustment mode of the fan)
Next, an adjustment mode for stabilizing the rotational speed of the blower fan F151 will be described with reference to FIGS. For example, after turning on the power of the apparatus, after a predetermined number of sheets are conveyed by the sheet feeding apparatus 3000, or after a predetermined time has elapsed, control is performed so as to shift to the adjustment mode of the fan F151. Here, the predetermined number may be a preset number or may be a number input from the operation screen. When the job operation is continuing after the predetermined number of sheets are conveyed by the sheet feeding device 3000, control may be performed so as to shift to the adjustment mode of the fan F151 after the job ends or before the job starts. Absent. In the present embodiment, the number of the fan F151 is one, but it may be plural. Further, the suction fan F150 may also be controlled to shift to the adjustment mode. It should be noted that the number of sheets fed by the sheet feeding device 3000 is counted by a control unit 300 (CPU 351) (not shown) that counts at the rising edge or falling edge of the signal output of the feeding sensor 620. Means).

  In FIG. 12, when an adjustment mode transition signal is detected after power-on, after a predetermined number of sheets are conveyed by the sheet feeding device 3000, or after a predetermined time has elapsed, the lowering operation of the tray 302 by the lifter motor M5 (lifter driving means) is performed. The process is started (FIG. 12A). When the tray 302 is detected by the lower position detection sensor 605, the lifter motor M5 is controlled to stop, and the tray 302 stops (see FIG. 12B). In this state, if a sheet is not detected by the sheet presence / absence detection sensor 606, the fan F151 is driven, and after a predetermined time has elapsed, the fan rotation speed adjustment is started (see FIG. 12C). That is, the adjustment of the amount of air blown from the blowing nozzle 151 that is the air blowing unit (the amount of air blown by the blowing fan F151) is started. Here, in order for the rotation speed adjustment by the blowing fan F151 to be performed normally, there is an obstacle (shield) in front of the air blowing portion (the blowing nozzle 151) by the blowing fan F151 (on the extended line in the air blowing direction). must not. For example, when the sheet bundle S stacked on the tray 302 is in front of the separation nozzle 151 by the separation fan F151 (on the extended line of the air blowing portion), the air flow path of the separation fan F151 is blocked, so that the normal rotation The number and wind pressure (air volume) cannot be obtained. Therefore, the tray 302 is controlled to be lowered by the lifter motor M5. When the tray 302 is detected by the lower position detection sensor 605, the lifter motor M5 stops. If no sheet is detected by the sheet presence / absence detection sensor 606 in this state, it can be determined that there is no obstacle in front of the whirling nozzle 151 (on the extended line of the air blowing portion), so the rotational speed adjustment of the whirling fan F151 is adjusted. It can be carried out.

  The rotation speed adjustment of the fan F151 will be described with reference to FIG. In a fan that can monitor the rotational speed, a target value is required to adjust the rotational speed of the fan. From the characteristics of the fan, it is known that when a fan is rotated with a predetermined PWM (Pulse Width Modulation) setting, a predetermined wind pressure is obtained at the same time as a predetermined rotation speed (FG) is output. For example, when a certain fan is operated at a PWM 100% setting, a rotational speed (FG) output of 600 Hz is made as the rotational speed output, and at the same time, 1000 Pa (Pascal) is obtained as the wind pressure. Assuming that the wind pressure required for adjusting the fan speed is 840 Pa, the target value range is set so that the fan speed is 500 Hz as the target value, 502 Hz as the target upper limit value, and 498 Hz as the target lower limit value. In other words, after a predetermined time (preset time) has elapsed after the start of the fan operation, the PWM value after the normal adjustment of the fan is set to 90% by controlling the fan speed to be adjusted, for example. Become. As described above, the reason for waiting for the elapse of the predetermined time after the start of the fan operation is waiting for the rotation speed of the fan to stabilize. After the rotational speed of the fan is stabilized, the rotational speed is adjusted, and control is performed so as to change the PWM value of the fan so that the rotational speed (FG) of the fan becomes a predetermined value. As a method for adjusting the rotation speed of the fan, a method in which the PWM value is decreased every predetermined value after the fan is rotated at a PWM value of 100%, or a value obtained by multiplying a coefficient that is a difference between the target value and the actual rotation speed is used. A method for increasing or decreasing the PWM value can be used. Further, when adjusting the rotation speed of the fan, the fan may be controlled to rotate at a predetermined PWM setting value instead of rotating at the PWM value of 100%.

  Further, with reference to FIG. 14, a state in which the driving PWM value of the fan is changed according to the seat condition after the rotation speed adjustment of the fan is normally completed will be described. FIG. 14 is an example, and the coefficient according to the sheet condition can be changed. As described above, a state in which a value of 90% is obtained as the PWM value for obtaining the necessary wind pressure 840 Pa as the adjustment value of the rolling fan is the wind pressure at which the thickest sheet can be rolled. That is, when the thickest sheet is selected, the PWM value of the fan is set to 90% × 1.0 = 90%. When thick paper is selected, the PWM value of the fan is set to 90% × 0.75 = 67.5%. When plain paper is selected, the PWM value of the fan is set to 90% × 0.5 = 45%. When thin paper is selected, the PWM value of the fan is set to 90% × 0.25 = 22.5%.

  A case where the rotation speed adjustment of a plurality of fans is simultaneously performed will be briefly described. As shown in FIG. 15, the plurality of fans are configured in a cascade connection, and a stronger wind pressure can be obtained by connecting a plurality of fans. For example, when a certain fan is operated at a PWM 100% setting, a rotation speed (FG) output of 220 Hz is made as a rotation speed output, and at the same time, a wind pressure of 300 Pa (Pascal) is obtained. It is assumed that the wind pressure necessary for adjusting the rotational speed of the fan is 840 Pa when four fans are connected in cascade. Then, the target values of the rotation speeds of the four fans, and the upper limit value and the lower limit value thereof are set as follows. That is, the target value range is set so that the rotation speed of the fan F101 is 182 Hz as the target value, 184 Hz as the target upper limit value, and 180 Hz as the target lower limit value. The target value range is set so that the rotation speed of the fan F102 is 171 Hz as the target value, 173 Hz as the target upper limit value, and 169 Hz as the target lower limit value. The target value range is set so that the rotation speed of the fan F103 is 181 Hz as the target value, 183 Hz as the target upper limit value, and 179 Hz as the target lower limit value. The target value range is set so that the rotation speed of the fan F104 is 162 Hz as the target value, 164 Hz as the target upper limit value, and 160 Hz as the target lower limit value. That is, control is performed so that the rotation speed of each fan is adjusted after a predetermined time has elapsed after the start of the fan operation. As a result, for example, the PWM value after normal adjustment of the fan is 92% for the fan F101, 87% for the fan F102, 91% for the fan F103, and 82% for the fan F104. Here, the case where the number of fans is four has been described, but the present invention is not limited to this, and the number of fans connected in cascade may be any number.

  Further, with reference to FIG. 14, a state in which the driving PWM value of the fan is changed according to the seat condition after the rotation speed adjustment of the fan is normally completed will be described. As described above, as the PWM values for obtaining the necessary wind pressure 840 Pa as the adjustment value of the fan, the fan F101 is 92%, the fan F102 is 87%, the fan F103 is 91%, and the fan F104 is 82%. This is the wind pressure at which the thickest sheet can be rolled. That is, when the thickest opening is selected, the PWM value of the fan F101 is 92% × 1.0 = 92%, the PWM value of the fan F102 is 87% × 1.0 = 87%, and the PWM value of the fan F103 is 91% × 1.0 = 91%, and the PWM value of the fan F104 is set to 82% × 1.0 = 82%. When thick paper is selected, the PWM value of the fan F101 is 92% × 0.75 = 69%, the PWM value of the fan F102 is 87% × 0.75 = 65.25%, and the PWM value of the fan F103 is 91% × 0.75 = 68.25%, and the PWM value of the fan F104 is set to 82% × 0.75 = 61.5%. When plain paper is selected, the PWM value of the fan F101 is 92% × 0.5 = 46%, the PWM value of the fan F102 is 87% × 0.5 = 43.5%, and the PWM value of the fan F103. Is set to 91% × 0.5 = 45.5%, and the PWM value of the fan F104 is set to 82% × 0.5 = 41%. When thin paper is selected, the PWM value of the fan F101 is 92% × 0.25 = 23%, the PWM value of the fan F102 is 87% × 0.25 = 21.75%, and the PWM value of the fan F103 is 91% × 0.25 = 22.75%, and the PWM value of the fan F104 is set to 82% × 0.25 = 20.5%.

  Next, a case where the rotation speed of the fan cannot be adjusted will be described with reference to FIG. When the adjustment mode transition signal is detected after the power is turned on, after a predetermined number of sheets are conveyed by the sheet feeding device 3000, or after a predetermined time has elapsed, the lowering operation of the tray 302 by the lifter motor M5 is started (FIG. 16A). reference). When the tray 302 is detected by the lower position detection sensor 605, the lifter motor M5 is controlled to stop, and the tray 302 stops (see FIG. 16B). In this state, when a sheet is detected by the sheet presence / absence detection sensor 606 (see FIG. 16C), control is performed to display a warning as shown in FIG. 17 on the operation screen. From this state, when the sheet storage unit is opened, several sheets stacked on the tray 302 are removed, and the sheet storage unit is closed again, the lowering operation of the tray 302 is started again. When the tray 302 is detected by the lower position detection sensor 605, the lifter motor M5 is controlled to stop, and the tray 302 stops. In this state, if a sheet is not detected by the sheet presence / absence detection sensor 606, the winding fan F151 is driven, and after a predetermined time has elapsed, the rotation speed adjustment of the fan is started.

  As for the adjustment mode for stabilizing the rotational speed of the fan described above, the adjustment mode may be selected from the operation screen as shown in FIG.

  Next, the operation after starting the rotation speed adjustment of the fan F151 will be described with reference to FIG. When the rotational speed adjustment of the fan F151 starts, if it falls within the target value range as shown in FIG. 13 within a predetermined time, the rotational speed adjustment of the fan is finished and the fan operation is stopped. To be controlled. At the same time, the lifter motor M5 is controlled to raise the tray 302. When the upper surface of the sheets stacked on the tray 302 is detected by the flying lower limit sensor 607, the lifter motor M5 is controlled to stop.

  On the other hand, in the case where the rotation speed of the fan F151 is not adjusted within the range of the target value as shown in FIG. 13 within a predetermined time (within a preset time) after the start of the adjustment of the rotational speed of the fan F151, Control is performed so as to stop the rotation speed adjustment and stop the operation of the blower fan F151. Subsequently, for example, as shown in FIG. 20, control is performed so as to display a warning that the rotation speed adjustment of the fan has failed. Here, the display is such that the rotation speed of the fan is adjusted again, but an error display may be used. Further, the warning may be stored in the internal storage device without displaying the warning as shown in FIG. Note that the warning that the rotation speed adjustment has failed may be displayed earlier than the operation stop timing of the fan F151.

  As described above, it is possible to adjust the rotation speed so as to obtain the necessary fan wind pressure by providing the rotation speed adjustment mode of the fan. Accordingly, the rotational speed can be set so that the fan can have an optimum wind pressure (air volume) regardless of variations in the fans themselves, changes in fan characteristics over time, or voltage drops due to bundled wires. Further, the rotation speed of the fan can be stabilized at the optimum rotation speed. In addition, due to the relationship between the fan speed and the fan wind pressure, even in a multiple connection configuration of multiple fans, it is possible to set an optimum wind pressure by setting a range of target values for adjusting the speed. it can.

  In the above-described embodiment, the tray 302 is lowered to the lower position in the rotation speed adjustment mode, and when it is determined that there is no sheet based on the detection of the sheet presence / absence detection sensor 606, the rotation speed adjustment of the fan F151 is adjusted. Although it started, it may be as follows. In the rotation speed adjustment mode, when the tray 302 is lowered and the sheet loading position detection sensor 609 detects the uppermost surface of the sheet bundle S supported by the tray 302, the rotation speed adjustment control is started. At this time, since the uppermost surface of the sheet bundle S is already positioned below the detection position of the sheet presence / absence detection sensor 606, it is not necessary to adjust the rotational speed based on the detection of the sheet presence / absence detection sensor 606. That is, when the sheet loading position detection sensor 609 detects the position of the uppermost surface of the sheet bundle S supported by the tray 302, the sheet bundle S is rolled in front of the blowing nozzle 151 (air blowing unit) by the fan F151. Is not located. In this control, if the lower position detection sensor 605 detects the tray 302 before the tray 302 is lowered and the sheet loading position detection sensor 609 detects the uppermost surface of the sheet, the presence / absence of a sheet according to the above-described embodiment. Control based on detection by the detection sensor 606 is performed.

  Further, the rotation speed adjustment of the fan F151 may be started as follows. The elevation of the tray 203 is counted by a counter so that the position of the tray 203 in the height direction can be known. That is, the position in the height direction of the tray 203 can be known by the count number by using an encoder provided in the lifter motor M5 or a stepping motor as the lifter motor. That is, the count number is set to 0 at the lower position so that the count number increases as the tray 203 rises. Then, the tray 302 is lowered by a predetermined count number in the rotation speed adjustment mode. The number of counts at this time is a number until the sheet bundle S stacked on the tray 302 disappears from the front of the firing nozzle 151 (air blowing portion) by the separation fan F151, and can be set in advance. In this case as well, if the lower position detection sensor 605 detects the tray 302 before counting the preset count, control based on the detection of the sheet presence / absence detection sensor 606 of the above-described embodiment is performed. Do.

  Incidentally, as shown in FIG. 12, depending on the type of sheet, even if the upper layer portion S1 of the sheet S on the tray 302 exists outside the spraying range of the separation nozzle 151, the air discharged from the separation nozzle 151 is contained in the sheet storage portion. It may circulate by and may blow up said S1. If the blown up S1 covers the firing nozzle 151 or closes the front of the firing nozzle 151, the correct rotation speed adjustment may not be possible.

  Even if the rotation speed can be adjusted correctly, if the sheet S1 blown up does not return to the original stacking position, the sheet cannot be fed and a feeding failure may occur.

  Whether or not the sheet is blown up is closely related to the size and basis weight of the sheet. That is, a small and light sheet is easily blown up. Further, depending on the temperature and humidity in the storage unit, an upward curl (curl having a convex bottom) may occur on the sheet, which may make it easier to blow up.

  If these are taken into consideration, it is most certain to adjust the rotation speed in a state where there is no sheet on the tray 302. The state where there is no sheet includes the time when all the paper on the tray 302 is used up, for example, when the sheet runs out while feeding the sheet. As described above, after the sheets are used up, the tray 302 is stopped at the sheet loading position by the sheet loading position detection sensor 609 in order to improve the sheet loading operation. At this position, since there is no obstacle in front of the firing nozzle 151, the rotational speed can be adjusted.

  Since it is not necessary to frequently adjust the number of rotations every time the paper on the tray 302 runs out, it is better to count the actual use (time, number of sheets) and store it in the storage device, and execute it at a certain interval. good. By doing so, it is possible to further reduce the time during which the user cannot use without operating the fan F151 unnecessarily.

  In order to keep the frequency low, it may be performed if it is determined that there is no paper after the apparatus is turned on. For example, when a mechanism for determining the amount of paper based on the position of the tray 302 (specifically, a pulse count by attaching an encoder to the drive motor) is inserted, the tray 302 is once lowered to the lowest position in order to initialize the position. The counter is then reset.

  As shown in FIG. 6, it is assumed that the tray 302 continues to rise and reaches the position of 302A indicated by a two-dot chain line in the drawing. Even if the tray 302 is confirmed by the sheet floating lower limit sensor 607, the sheet presence / absence detection sensor flag 606F does not rotate and the sheet presence / absence detection sensor 606 does not turn on because the hole 302H is formed in the tray. Therefore, it can be seen that there is no sheet on the tray 302.

  If it is determined that there is no paper, the sheet loading position detection sensor 609 is once turned on by the sheet loading position detection sensor flag 609F when the sheet loading position, that is, the tray 302 is lowered, and then stopped at the position where it is further turned off, that is, the position 302B. At this position, since there is no obstacle on the front surface of the firing nozzle 151, the rotational speed can be adjusted accurately.

  If the sheet loading position detection sensor 609 is not provided, the tray 302 may be stopped anywhere as long as the state where there is no obstacle on the front surface of the firing nozzle 151 can be achieved regardless of this position.

  In the above-described embodiment, the configuration in which the sheet feeding device includes two sheet feeding units having an air separation feeding mechanism is exemplified. However, the number of sheet feeding units having an air separation feeding mechanism is as follows. However, the present invention is not limited to this, and may be set as necessary.

  In the above-described embodiment, the sheet feeding device having the sheet separation fan (air separation and feeding mechanism) is exemplified by the sheet feeding device installed on the upstream side in the sheet conveying direction with respect to the image forming apparatus main body. did. However, the present invention is not limited to these, and is effective when applied to, for example, a sheet feeding apparatus provided integrally with the main body of the image forming apparatus.

  In the above-described embodiment, the sheet feeding device that separates and feeds the sheets to be recorded one by one is illustrated, but the present invention is not limited to this, and the sheets to be read are separated one by one. It is also effective when applied to a sheet feeding apparatus for feeding.

Schematic sectional view showing a configuration in which the sheet feeding apparatus according to the present embodiment is arranged in an image forming apparatus Sectional drawing which shows an example of the sheet separation feeding part of the sheet feeding apparatus of this Embodiment Control block diagram of the sheet feeding apparatus of the present embodiment 1 is a block diagram illustrating the configuration of a control unit of a printer main body and a control unit of a sheet feeding apparatus according to an embodiment. Schematic showing an operation unit in the image forming apparatus of the present embodiment Explanatory drawing of the position which adjusts the rotation speed of the whirling fan of this Embodiment Sectional drawing which shows an example of the sheet separation feeding part of the sheet feeding apparatus of this Embodiment (A) The figure which shows the logic of the sheet levitation upper limit sensor and the sheet levitation lower limit sensor in a standby state, (b) The figure which shows the logic of the sheet levitation upper limit sensor and the sheet levitation lower limit sensor after the operation of the rolling fan The figure which shows the sheet | seat detection lower limit of a sheet levitation upper limit sensor and a sheet levitation lower limit sensor The figure which shows the screen which inputs the sheet condition on the operation screen Diagram showing top sheet surface control when normal The figure showing the case where the rotation speed of the fan can be adjusted The figure showing the range of the target value when adjusting the number of rotations of the fan Diagram showing coefficient of adjustment value for sheet condition Sectional view showing the case of multiple cascaded fan connection configuration A figure showing the case where the rotation speed of the fan cannot be adjusted A figure showing a warning on the operation screen before adjusting the rotation speed of the fan A figure showing how to select whether to adjust the rotation speed on the operation screen The figure which shows the operation after the rotation speed adjustment of the fan is completed normally The figure showing the warning on the operation screen when the rotation speed adjustment of the fan is unsuccessful

Explanation of symbols

F150, F250 ... Suction fan F151, F251 ... Shooting fan
M102, M202 ... Adsorption belt motor M5, M105 ... Lifter motor (lifter driving means)
S ... sheet 1 ... image forming apparatus 100, 104 ... sheet storage unit 130 ... control unit 131 ... control unit 151 ... firing nozzle (air spraying unit)
225 ... Display section (operation screen)
300 ... Control unit (control means)
301, 311... Sheet storage portion 302, 312. Rotational speed detection sensor (Rotational speed detection means)
605 ... Tray lower position detection sensor (lower position detection means)
606 ... Sheet presence / absence detection sensor (sheet presence / absence detection means)
607... Sheet floating lower limit sensor 608. Sheet floating upper limit sensor 609. Sheet loading position detection sensor 610... Unit 1005 ... Image forming unit 2000 ... Scanner 3000 ... Sheet feeding device

Claims (9)

A tray provided to support a plurality of sheets;
An air blowing section for blowing air for spreading the sheet toward the end of the sheet supported by the tray;
A sheet presence / absence detecting means for detecting the presence / absence of a sheet on the tray;
With
When the sheet presence / absence detecting means detects that there is no sheet on the tray, the tray is lowered until it is not positioned in front of the position where the air is blown from the air blowing unit, and then from the air blowing unit. A sheet feeding apparatus that adjusts an air blowing amount. The tray is provided so that it can be moved up and down, a sheet-spreading fan is provided in the air blowing section, and a rotational speed detection means for detecting the rotational speed of the sheet-spreading fan is provided . The sheet feeding device according to claim 1, wherein the rotation speed of the fan is adjusted.   The rotation number of the seating fan is adjusted so that the number of rotations of the seating fan detected by the rotation number detection means falls within a preset target value range. Sheet feeding device.   4. The seat rolling fan includes a plurality of fans, and a target value range for adjusting the rotational speed can be set for each of the plurality of fans. Sheet feeding device.   The sheet feeding device according to claim 2, wherein the rotation speed is adjusted after a preset time from the start of the operation of the sheet rolling fan.   After starting the operation to adjust the rotational speed of the seating fan, when the rotational speed of the seating fan falls within the target value range, a signal indicating that the adjustment of the seating fan has been completed normally is output. The sheet feeding device according to claim 3, wherein the sheet feeding device is a sheet feeding device.   If the rotation speed of the seating fan does not fall within the target value within a preset time after starting the adjustment of the rotation speed, the operation of the seating fan is stopped and the operation screen is displayed. The sheet feeding apparatus according to claim 6, wherein a warning is displayed on the sheet feeding apparatus.   3. The sheet feeding apparatus according to claim 2, wherein the number of rotations of the sheet winding fan is adjusted after the power is turned on or when the sheet runs out while feeding the sheet.   An image forming apparatus comprising: the sheet feeding device according to claim 1; and an image forming unit that forms an image on a sheet fed by the sheet feeding device.

Images