SHEET FEEDER, DOCUMENT READER, AND IMAGE FORMING APPARATUS

摘要

A sheet feeder picking up and transporting sheets includes a transport unit transporting sheets along a sheet transport path one by one, a gap occurrence detection unit detecting, within a predetermined section of the sheet transport path, occurrence of a gap between sheets, and a controller controlling a timing of the transport of sheets according to a result of the detection. The gap occurrence detection unit includes a first detection unit and a second detection unit. The first detection unit is configured to detect light that is emitted toward the predetermined section, reaches a converging surface thereof across the predetermined section, and converged on a receiving element thereof. The second detection unit is configured to detect light reflected by a sheet passing through the predetermined section. The occurrence of the gap is detected based on outputs from the first detection unit and the second detection unit.

主权项

1. A sheet feeder for sequentially picking up sheets from a sheet stack and continuously transporting the sheets along a sheet transport path, the sheet feeder comprising:
a transport unit that transports the sheets along the sheet transport path one by one; a gap occurrence detection unit that detects, within a predetermined section of the sheet transport path, occurrence of a gap between the trailing edge of a preceding sheet and the leading edge of a following sheet; and a controller that controls a timing at which the transport unit starts transporting the following sheet according to a result of the detection by the gap occurrence detection unit, the gap occurrence detection unit including a first detection unit and a second detection unit, the first detection unit including:
a first light emitting element that is disposed on a first side of the sheet transport path and emits diffused light at least toward the predetermined section;a first light receiving element that is disposed on the first side of the sheet transport path; anda converging reflector that is disposed on a second side of the sheet transport path opposite the first side and converges, onto the first light receiving element, light that is emitted by the first light emitting element and reaches the converging reflector by travelling across the predetermined section, and the second detection unit including:
a second light emitting element; anda second light receiving element that is located in a position to detect light emitted by the second light emitting element and reflected by a sheet passing through the predetermined section, whereinthe gap occurrence detection unit detects occurrence of the gap based on outputs from the first detection unit and the second detection unit while the preceding sheet and the following sheet are passing through the predetermined section.