SHEET FEEDING APPARATUS AND IMAGE FORMING APPARATUS

Abstract

An image forming apparatus has a sheet feeding apparatus which separates and feed a sheet one by one using a loosening fan which blows air from an air blowing portion for loosening the sheet on a tray. The rotating speed of the sheet loosening fan is adjusted while the sheet supported by the tray is not located in front of a position where the air is blown from the air blowing portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a schematic configuration in which a sheet feeding apparatus according to an embodiment is arranged on an input side of an image forming apparatus;

FIG. 2 is a sectional view illustrating an example of a sheet separating and feeding portion of the sheet feeding apparatus of the embodiment;

FIG. 3 illustrates a control block diagram of the sheet feeding apparatus of the embodiment;

FIG. 4 is a block diagram illustrating configurations of a control unit of a printer body of the embodiment and a control unit of the sheet feeding apparatus of the embodiment;

FIG. 5 is a sectional view illustrating a schematic configuration in which the sheet insertion apparatus according to an embodiment is arranged on an output side of the image forming apparatus;

FIG. 6 illustrates a schematic configuration of an operation portion of the sheet feeding apparatus of the embodiment;

FIG. 7 illustrates a screen in which sheet conditions are inputted on an operation screen;

FIG. 8 illustrates a coefficient for an adjustment value with respect to the sheet condition;

FIG. 9 is a sectional view illustrating an example of a sheet separating and feeding portion of the sheet feeding apparatus according to the embodiment;

FIG. 10 illustrates detectable lower limits of a sheet floatation upper-limit sensor and a sheet floatation lower-limit sensor;

FIG. 11A illustrates logic of the sheet floatation upper-limit sensor and the sheet floatation lower-limit sensor in a standby state;

FIG. 11B illustrates logic of the sheet floatation upper-limit sensor and the sheet floatation lower-limit sensor after a loosening fan is operated;

FIGS. 12A to 12C illustrate control of an uppermost sheet surface in the normal case;

FIGS. 13A to 13C illustrate cases where a fan rotating speed can be adjusted;

FIGS. 14A to 14C illustrate cases where the fan rotating speed cannot be adjusted;

FIG. 15 illustrates a range of a target value when the fan rotating speed is adjusted;

FIG. 16 illustrates selection whether or not an air quantity is adjusted from an operation screen;

FIG. 17 is a flowchart illustrating adjustment of fan air quantity according to the embodiment;

FIG. 18 illustrates warning on the operation screen before the fan rotating speed is adjusted;

FIG. 19 illustrates warning on the operation screen when the adjustment of the fan rotating speed fails;

FIGS. 20A and 20B illustrate operation after the adjustment of the fan rotating speed is normally ended;

FIG. 21 illustrates a timing chart from start of the adjustment of the fan rotating speed to the normal end;

FIG. 22 illustrates a timing chart when the fan rotating speed is not adjusted;

FIG. 23 illustrates a timing chart from start of the adjustment of the fan rotating speed to the normal end after a sheet is removed; and

FIG. 24 illustrates a timing chart explaining control after the adjustment of the fan rotating speed fails.

Claims

1. An image forming apparatus that has a sheet feeding apparatus which separates and feeds a sheet one by one, the image forming apparatus comprising: a tray which supports a plurality of sheets;an air blowing portion which loosens the sheet by blowing air to an end portion of the sheet supported by the tray; andwherein an amount of blowing air from the air blowing portion is adjusted while the sheet supported by the tray moves away from a position at where the sheets are loosened by the air blowing portion.

2. The image forming apparatus according to claim 1, further comprising: a sheet loosening fan which is provided in the air blowing portion,wherein the tray is provided capable of lifting and lowering, and the rotating speed of the sheet loosening fan is adjusted while the sheet supported by the tray is not located in front of a position where the air is blown from the air blowing portion.

3. The image forming apparatus according to claim 2, further comprising: a rotating-speed detecting unit which detects a rotating speed of the sheet loosening fan; anda control unit which controls a lifting and lowering operation of the tray and an operation of the sheet loosening fan,wherein the rotating speed of the sheet loosening fan detected by the rotating-speed detecting unit is adjusted by the control unit so as to fall within a predetermined range of a target value.

4. The image forming apparatus according to claim 3, further comprising: a lower position detecting unit which detects that the tray is located at a lower position which is of the lowest position within a lifting and lowering range of the tray; anda sheet existence detection unit which detects presence or absence of the sheet supported by the tray;wherein a position where the sheet existence detection unit detects the absence of the sheet on the tray is set such that the sheet supported by the tray is below the position where the air is blown from the sheet loosening fan, andthe control unit lowers the tray until the lower position detecting unit detects the tray, and the control unit starts an adjusting operation of the rotating speed of the sheet loosening fan when the sheet existence detection unit detects the absence of the sheet while the tray is located at the lower position.

5. The image forming apparatus according to claim 3, further comprising: a sheet loading position detecting sensor which detects an uppermost surface of the sheet supported by the tray in the lifting and lowering range of the tray, the sheets is loaded on the tray which is stopped based on the detection of the sheet loading position detecting sensor,wherein, after the control unit lowers the tray until the sheet loading position detecting sensor detects the uppermost surface of the sheet, the control unit starts the adjusting operation of the rotating speed of the sheet loosening fan.

6. The image forming apparatus according to claim 5, further comprising: a lower position detecting unit which detects that the tray is located at a lower position which is of the lowest position within a lifting and lowering range of the tray; anda sheet existence detection unit which detects presence or absence of the sheet supported by the tray;wherein a position where the sheet existence detection unit detects the absence of the sheet on the tray is set such that the sheet supported by the tray is below the position where the air is blown from the sheet loosening fan, andthe control unit lowers the tray, and the control unit starts an adjusting operation of the rotating speed of the sheet loosening fan when the lower position detecting unit detects the tray before the sheet loading position detecting sensor detects the uppermost surface of the sheet and, when the sheet existence detection unit detects the absence of the sheet.

7. The image forming apparatus according to claim 6, wherein the control unit does not perform the adjusting operation of the rotating speed of the sheet loosening fan but displays a warning on an operation screen, when the lower position detecting unit detects the tray and, when the sheet existence detection unit detects the presence of the sheet.

8. The image forming apparatus according to claim 5, further comprising: a sheet existence detection unit which detects presence or absence of the sheet supported by the tray,wherein in case that the sheet existence detection unit detects the absence of the sheet on the tray, the tray moves downwards until the sheet leading position detecting sensor detects the tray, and then a process to adjust the rotating speed of the sheet loosing fan begins in a status that the tray stays at a lowered position.

9. The image forming apparatus according to claim 3, wherein the control unit controls to adjust the rotating speed after a predetermined time elapses since an operation of the sheet loosening fan is started.

10. The image forming apparatus according to claim 3, wherein the control unit outputs a signal indicating that the sheet loosening fan is normally ended, when the rotating speed of the sheet loosening fan falls within the range of the target value after the control unit starts the adjusting operation of the rotating speed of the sheet loosening fan.

11. The image forming apparatus according to claim 3, wherein the control unit performs control to adjust the rotating speed of the sheet loosening fan for a predetermined time.

12. The image forming apparatus according to claim 3, wherein the control unit stops the operation of the sheet loosening fan to display the warning on the operation screen, when the rotating speed of the sheet loosening fan does not fall within the range of the target value within a predetermined time since the adjustment of the rotating speed is started.

13. The image forming apparatus according to claim 3, wherein the control unit stops the operation of the sheet loosening fan and lifts the tray until the sheet existence detection unit detects the presence of the sheet, when the rotating speed of the sheet loosening fan falls within the range of the target value within a predetermined time since the adjustment of the rotating speed is started.

14. The image forming apparatus according to claim 3, wherein the control unit adjusts the rotating speed of the sheet loosening fan, after the power is turned on, or after any number of sheets are conveyed.