Riso Kagaku Corporation

Tomoko Nagano

Masakazu Miyata

Kosai Adachi

A cut sheet feeder for an image forming apparatus is basically formed of one sheet feed mechanism for picking up stacked cut sheets at a single sheet feed position, a sheet feed unit vertically movable relative to the sheet feed mechanism, a cassette detachably attached to the sheet feed unit and containing the cut sheets, and a sheet feed table vertically movably situated inside said sheet feed unit and carrying a large number of the cut sheets.. The feeder further includes a cassette presence detection device for detecting presence or absence of the cassette on the sheet feed unit, a cover detection device for indicating an opening status of a cover for the sheet feed unit, a mode establishment device for establishing a cassette feed mode or a table feed mode, and a mode control device for controlling the sheet feed unit. The mode control device lowers the sheet feed unit to a predetermined position in case the cassette feed mode is changed to the table feed mode by the mode establishment device while the cover detection device outputs a detection signal indicating a closed status of the cover and the cassette presence detection device outputs a signal indicating the presence of the cassette.

Cut sheet feeder for image forming apparatus

A cut sheet feeder for use with an image forming apparatus is formed of a sheet feed mechanism for picking up stacked cut sheets one at a time from a single sheet feed position and for feeding each sheet to an image recording portion; a sheet feed unit which is vertically movable relative to the sheet feed mechanism and to which a cassette containing cut sheets may be attached in a detachable manner; a sheet feed table which is vertically movable within the sheet feed unit and which carries a large number of cut sheets; a cassette presence detection device for detecting the presence and absence of a cassette on the sheet feed unit and for outputting a signal indicating either the presence or the absence of the cassette; a power switch for starting and stopping the cut sheet feeder; and a mode establishment device. A cassette feed mode involving the cassette for minority sheet feed is established if the detection signal from the cassette presence detection device indicates the presence of the cassette when the power switch is turned on, and a table feed mode involving the sheet feed table for majority sheet feed is established if the detection signal from the cassette presence detection device indicates the absence of the cassette.

A cut sheet feeder for use with an image forming apparatus, is formed of: a sheet feed mechanism for picking up stacked cut sheets one at a time from a single sheet feed position and for feeding each sheet to an image recording portion; a sheet feed unit which is vertically movable relative to the sheet feed mechanism and to which a cassette containing cut sheets may be attached in a detachable manner; a sheet feed table which is vertically movable within the sheet feed unit and which carries a large number of cut sheets; a plurality of detectors for detecting the positions of the sheet feed unit, the sheet feed table and the cut sheets relative to the sheet feed position; and a sheet overload detector. The overload is detected by the detectors with respect to the relative position between the sheet feed unit and the sheet feed table with reference to the sheet feed position. A mode controller controls the vertical movement of the sheet feed unit and the sheet feed table and stops the vertical movement when the detection signal from the sheet overload detector is admitted.

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Ibaraki, Japan

Tomoko Nagano