System for detecting reflecting objects

• US 3,977,792 A
• Filed: 12/16/1974
• Issued: 08/31/1976
• Est. Priority Date: 12/17/1973
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sunada, Masayoshi, Kawano, Shigeyoshi, Jumonji, Hiroshi
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Rosenberger, Richard A.
• Application Number:
  US05/533,084
• Time in Patent Office: 624 Days
• Field of Search: 250/202, 250/209, 356/209, 330/59, 330/84, 330/124 R, 330/84, 330/58
• US Class Current: 356/445
• CPC Class Codes: G05D 1/0244 using reflecting strips

Abstract

In a system for optically detecting with a plurality of light detecting elements a reflecting object in the form of long stripe disposed on the surface of a traveling path, the average value of the respective electric quantities derived from the light detecting elements is obtained through arithmetic operation and the reference value is automatically changed according to the degree of the surface being soiled, by multiplying the average value by a certain safety factor, so that accurate detection can be performed independent of the degree of the soil on the traveling path surface.

Claims

1. A system for detecting reflecting objects comprising

a reflector supported on a supporting body,

means for directing light on said supporting body and said reflector,

a plurality of light detecting elements for receiving reflected light from said supporting body and said reflector, each of said plurality of light detecting elements producing an electrical output in response to light received from said supporting body and said reflector, said reflector being detected by a specific one of said plurality of said light detecting elements,

means for detecting said reflector by comparing the electrical output of said specific one of said plurality of light detecting elements with a reference signal, and

means for generating said reference signal from the average value of all of said electrical outputs from said plurality of light detecting elements.

2. A system for detecting reflecting objects according to claim 1, wherein said reference signal is generated by increasing said average value by a predetermined factor.

3. A system for detecting reflecting objects according to claim 2, wherein said predetermined factor maintains said reference signal between said average value and said electrical output for each of said plurality of light detecting elements.

4. A system for detecting reflecting objects according to claim 2, wherein said means for generating said reference signal includes an amplifier having the electrical outputs of said plurality of light detecting elements for an input.

5. A system for detecting reflecting objects according to claim 4, wherein said means for detecting said reflector includes one of a plurality of amplifiers corresponding to said plurality of light detecting elements, each of said plurality of amplifiers having a first input of a respective electrical output of one or said plurality of light detecting elements and a second input of said reference signal.

6. A system for detecting reflecting objects according to claim 4, wherein said predetermined factor is provided by predetermined resistances for said electrical outputs being input to said amplifier.

7. A system for detecting reflecting objects according to claim 1, wherein said means for generating said reference signal includes an amplifier having the electrical outputs of said plurality of light detecting elements for an input.

8. A system for detecting reflecting objects according to claim 7, wherein said means for detecting said reflector includes one of a plurality of amplifiers corresponding to said plurality of light detecting elements, each of said plurality of amplifiers having a first input of a respective electrical output of one of said plurality of light detecting elements and a second input of said reference signal.

9. A system for detecting reflecting objects according to claim 1, wherein said supporting body is a surface of a traveling path.