Sensor and method of detecting the condition of a turf grass

• US 7,929,141 B2
• Filed: 01/10/2008
• Issued: 04/19/2011
• Est. Priority Date: 08/01/2003
• Status: Expired due to Fees

• Current Assignee: Li & S Company Limited (Yesco Holdings Co., Ltd.)
• Original Assignee: Li & S Company Limited (Yesco Holdings Co., Ltd.)
• Inventors: Biggs, Gregory L, Ediger, Kevin, Franzen, David, Demetriades-Shah, Tanvir, Welles, Jonathan M., Rada, John
• Primary Examiner(s): Toatley, Jr.; Gregory J
• Assistant Examiner(s): VALENTIN II, JUAN D
• Application Number:
  US12/008,402
• Publication Number:
  US 20080316491A1
• Time in Patent Office: 1,195 Days
• Field of Search: None
• US Class Current: 356/445
• CPC Class Codes: A01D 34/006 Control or measuring arrangements
• CPC Class Codes: G01N 21/55 Specular reflectivity

Abstract

A method of detecting the condition of a turf grass is described. According to one aspect of the invention, the method comprises steps of attaching an active sensor to a mower; traversing a section of turf grass; and processing the output of the sensor. A device for detecting the condition of turf grass is also disclosed. The device comprises an array of illuminating devices generating a pattern of illuminating light; a detecting device receiving a pattern of reflected light which is coincident with the pattern of illuminating light; a detecting device adapted to detect stray light from the array of illuminating devices; and a feedback loop controlling the array of illuminating devices. A system employing the device is also disclosed.

Claims

1. A. device for detecting a condition of turf grass, said device comprising:

an array of LEDs generating a pattern of illuminating light;

at least one photodetector receiving a pattern of reflected light which is coincident with said pattern of illuminating light;

one or more photodetectors that detect stray light from said array of LEDs;

a feedback loop controlling said array of LEDs based upon stray light from said array of LEDs;

wherein said feedback loop comprises more than one demodulator for more than one frequency;

a circuit for providing offset correction, said circuit comprising a first offset correction circuit for a first frequency and a second offset correction circuit for a second frequency; and

a background light subtraction circuit.