Optical sensor including a first and second converging optical system for edge detection

• US 5,929,436 A
• Filed: 08/18/1997
• Issued: 07/27/1999
• Est. Priority Date: 05/08/1995
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Baba, Nobuyuki, Aoki, Sumiaki, Kudo, Koichi, Murai, Toshiharu
• Primary Examiner(s): Allen, Stephone B.
• Application Number:
  US08/912,368
• Time in Patent Office: 708 Days
• Field of Search: 250/234-236, 250/216, 250/559.36, 359/17
• US Class Current: 250/234
• CPC Class Codes: G03G 15/607 for detecting size, presence or position of original
• CPC Class Codes: H04N 1/00681 Detecting the presence, position or size of a sheet or correcting its position before scanning H04N1/047 takes precedence; mode signalling H04N1/333; skew detection or correction in image signals H04N1/3878
• CPC Class Codes: H04N 1/00737 using the scanning elements as detectors
• CPC Class Codes: H04N 1/00748 Detecting edges, e.g. of a stationary sheet
• CPC Class Codes: H04N 1/00753 of a sheet relative to a particular backgroud
• CPC Class Codes: H04N 1/00769 Comparing, e.g. with threshold
• CPC Class Codes: H04N 1/113 using oscillating or rotating mirrors

Abstract

An original placement table is provided, on which an original sheet is placed. An original scanning device causes a light beam to scan the original sheet placed on the original placement table. A light receiving device receives a light beam which has been reflected by the original sheet placed on the original placement table after being emitted by the original scanning device. An original edge determining device monitors light intensity of the light beam received by the light receiving device. The original edge determining device determines that the light beam currently being received by the light receiving device is the light beam reflected by an edge of the original sheet placed on the original placement table when a significant variation is detected in the light intensity either for the first time or for the last time in one scanning operation of the original scanning device.

Claims

1. An optical sensor comprising:

a light scanning mechanism which causes light emitted by a light-emitting diode to scan for a to-be-detected object;

a converging optical system which causes the light emitted by said light-emitting diode to converge on the to-be-detected object;

a beam splitter which partially reflects the light which has been reflected by the to-be-detected object, the reflected light being incident on light receiving means; and

another converging optical system which causes the light reflected by said beam splitter to converge on said light receiving means.

2. An optical sensor comprising:

a light scanning mechanism which causes light emitted by a light-emitting diode to scan for a to-be-detected object;

a converging optical system which causes the light emitted by said light-emitting diode to converge on the to-be-detected object; and

a beam splitter which partially reflects the light which has been reflected by the to-be-detected object, the reflected light being incident on light receiving means,

wherein said converging optical system further causes the light reflected by said beam splitter to converge on said light receiving means.

3. An optical sensor comprising:

a light scanning mechanism which causes light emitted by a light-emitting diode to scan for a to-be-detected object;

a first converging optical system which causes the light emitted by said light-emitting diode to converge on the to-be-detected object; and

a second converging optical system which causes the light reflected by said to-be-detected object to converge on light receiving means;

wherein said second converging optical system is located in a reflecting optical path along which the light reflected by the to-be-detected object extends, said reflecting optical path being different from a scanning optical path along which the light emitted by said light-emitting diode extends to the to-be-detected object.