US 5,347,350 AGranted

Sheet feeder

AssigneeMita Industrial Co., Ltd.

InventorsAkinobu Nakahata, Hiroshi Kubota, Kouji Migita, Masami Fuchi, Kenji Oda, Yoshinori Makiura, Katsuhide Yamaguchi

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Abstract

A sheet feeder includes a feeder for feeding a sheet, a cassette for containing a plurality of stacks of small sized sheets side by side therein, the cassette including a plurality of biasing members for biasing the respective stacks of small sized sheets upwards so as to bring uppermost sheets of the respective stacks into contact with the feeder, a plurality of sheet detectors arranged in positions corresponding to the respective stacks of sheets for detecting the height of the respective stacks of sheets contained in the cassette, and a controller responsive to the plurality of sheet detectors for determining the absence of sheet in the cassette when at least one of the plurality of sheet detectors detects that the height of the stack has become lower than a predetermined height, and stopping a sheet feeding operation. This sheet feeder prevents the transfer device of an image forming apparatus from being smeared due to the fact that the small sized sheet is fed from only one stack.

A sheet feeding arrangement comprising:

a feeder for feeding at least one sheet;
a cassette comprising means for holding at least a first stack of sheets, and biasing means for biasing sheets in said cassette upwards so as to bring uppermost sheets of said at least one stack into contact with the feeder;
a plurality of sheet detectors arranged in positions corresponding to the respective stacks of sheets for detecting the height of the respective stacks of sheets contained in the cassette means;
said detectors being spaced apart in a direction perpendicular to the feed direction of said feeder;
control means responsive to outputs of said plurality of sheet detector means for determining the absence of sheets in the cassette means when at least one of the plurality of sheet detectors detects that the height of a stack of sheets thereunder has become lower than a predetermined height, and for stopping a sheet feeding operation by said feeder;
said cassette comprising means for holding a second stack of sheets spaced from said first stack in the direction perpendicular to the feed direction of said feeder, said sheet detector means comprising first and second detectors for detecting the heights of said first and second stacks, respectively, and said control means comprises means for stopping the sheet feeding operation in response to the detection by at least one of said detector means that the height of the respective stack is below said predetermined height;
said cassette being shaped to permit the selective loading of a single stack of sheets of larger size than the sheets of said first and second stacks, to replace said first and second stacks of sheets, with said first and second detectors positioned to detect the height of said single stack at spaced apart locations, and further comprising means for determining the presence of said single stack in said cassette, and wherein said control means is responsive to the detection of said single stack in said cassette for stopping said feeder only when said first and second detectors both detect the presence of sheets that the height of said single stack is below said predetermined height.

4 more elements

Facts

Application

08/127,469Filed 24 Sep 1993 · continuation

Priority

JP 3-21569028 Aug 1991

Granted

13 Sep 1994

Term ends

Not estimatedThe source records don’t support an estimate.

Classification8 codes

B65H 7/04
By feelers or detectors: responsive to absence of articles, e.g. exhaustion of pile
B65H 2511/15
Size; Dimensions: height, e.g. of stack
B65H 2511/20
Dimensions; Position; Numbers; Identification; Occurrences: location in space
B65H 2511/212
Angle: rotary position

Abstract

Claims18