SHEET FEEDING DEVICE AND IMAGE FORMING APPARATUS

Abstract

A sheet feeding device which blows air to placed sheets, separates and conveys the sheets includes a sheet containing portion which contains the sheets, an air blowing portion which blows air to the sheets contained in the sheet containing portion, and an air supply unit which supplies air to the air blowing portion. The air supply unit is constituted by connecting two or more centrifugal fans, and the air blown out from an upstream side fan in an air flow passage is sucked by an adjacent downstream side fan via a spiral flow passage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective explanatory diagram illustrating an air supply unit;

FIG. 2 is an explanatory diagram illustrating a flow of air in two centrifugal fans taken out from the constitution of FIG. 1;

FIGS. 3A and 3B are explanatory diagrams illustrating a connecting member that connects the two centrifugal fans;

FIG. 4 is an explanatory diagram illustrating an example where a revolving direction of a spiral flow passage of the connecting member is different from a rotating direction of impeller of the downstream side fan;

FIG. 5 is a constitutional explanatory diagram illustrating an air supply unit having two units composed of the upstream side fan and the downstream side fan;

FIG. 6 is a schematic sectional explanatory diagram illustrating an image forming apparatus having a sheet feeding device;

FIG. 7 is an explanatory diagram illustrating the sheet feeding device;

FIG. 8 is an explanatory diagram illustrating an air adsorption separation feeding constitution; and

FIG. 9 is an explanatory diagram illustrating the air adsorption separation feeding constitution according to a conventional art.

Claims

1. A sheet feeding device having an air loosening mechanism for blowing air to placed sheets so as to loosen the sheets, the sheet feeding device comprising: a sheet containing portion which contains the sheets;an air blowing portion which brows air to ends of the sheets contained in the sheet containing portion; andart air supply unit which supplies air to the air blowing portion,wherein the air supply unit has a plurality of centrifugal fans and is constituted so that the centrifugal fans are connected serially by a spiral flow passage.

2. The sheet feeding device according to claim 1, wherein an air supply opening of the centrifugal fan on an upstream side in a direction of air flowing in the air supply unit and an air suction opening of the centrifugal fan on a downstream side are connected by a connecting member which forms the spiral flow passage.

3. The sheet feeding device according to claim 2 wherein, a rotational flow direction of the air in the spiral flow passage is set so as to be the same as a rotating direct-on of an impeller of the centrifugal fan on the downstream side.

4. The sheet feeding device according to claim 2, wherein a center of the rotational glow of the air in the spiral flow passage is equal to the rotating center of the impeller of the centrifugal fan on the downstream side.

5. The sheet feeding device according to claim 1, wherein a plurality of air supply units constituted by combining the plural centrifugal fans serially are arranged in parallel, and the respective air supply units are connected at the downstream side in the air flow direction.

6. An image forming apparatus including a sheet feeding device having an air loosening mechanism for blowing air to placed sheets to loosen the sheets and an image forming portion for forming an image on sheets fed from the sheet feeding device, the image forking apparatus comprising: a sheet containing portion which contains the sheets;an air blowing portion which blows air to ends of the sheets contained in the sheet containing portion; andan air supply unit which supplies air to the air blowing portion,wherein the a r supply unit has a plurality of centrifugal fans and is constituted so that the respective centrifugal fans are connected serially by a spiral flow passage.