Light sources adapted to spectral sensitivity of plants

• US 10,973,173 B2
• Filed: 06/26/2018
• Issued: 04/13/2021
• Est. Priority Date: 07/10/2012
• Status: Active Grant

• Current Assignee: Signify North America Corporation (Signify N.V.)
• Original Assignee: Signify North America Corporation (Signify N.V.)
• Inventors: Grajcar, Zdenko, Payne, Kevin
• Primary Examiner(s): Hayes, Kristen C
• Application Number:
  US16/018,556
• Publication Number:
  US 20180295788A1
• Time in Patent Office: 1,022 Days
• CPC Class Codes: A01G 7/045 with electric lighting
• CPC Class Codes: A01G 9/249 Lighting means with special arrangements for promoting growth A01G7/045
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: Y02P 60/14 Measures for saving energy, e.g. in green houses

Abstract

A method of stimulating plant growth in a controlled environment that includes providing a lighting assembly having a network of lighting elements such as light emitting diodes (LEDs) that provide light at a color tailored for an individual plant. The lighting assembly is positioned adjacent a plant such that the light produced is received by the plant. The lighting assembly additionally has a control assembly that includes driving circuitry that modulates the lighting elements to controllably provide predetermined periods of light and dark to stimulate continuous growth of the plant.

Claims

1. A lighting system of enhancing growth in plants comprising:

an alternating current (AC) input providing an input voltage to provide an applied electrical excitation;

a plurality of light emitting diodes (LEDs) arranged in a first network that receive a load current based on the applied electrical excitation;

said plurality of LEDs in the first network producing a first light output at a first wavelength that is within 20 nm of a peak absorption of a first predetermined pigment of a plant;

a plurality of LEDs arranged in a second network that receives the load current based on the applied electrical excitation;

said plurality LEDs in the second network producing a second light output at a second wavelength that is within 20 nm of a peak absorption of a second predetermined pigment of the plant; and

a control module electrically connected to the AC input to simultaneously modulate the first and second light outputs between light and dark wherein the predetermined periods of light and dark have a phase of 24 milliseconds (ms).

2. The system of claim 1 wherein the control module determines a frequency of the AC input.

3. The system of claim 2 wherein the AC input provided to the control module has a frequency of 60 Hz or less to modulate the first light output and the second light output.

4. The system of claim 1 wherein the control module is a dimming device.

5. The system of claim 1 further comprising:

driving circuitry receiving the input voltage from the AC input and conditioning the load current to provide a first input current to the first network and a second load current to the second network;

wherein during operation the first input current provides to the first network when the second input current provides no current to the second network.

6. The system of claim 1 wherein the first predetermined pigment is Chlorophyll A;

and

the peak absorption wavelength of the first predetermined pigment is selected from a list consisting of 390 nm, 410 nm and 690 nm.

7. The system of claim 6 wherein the second predetermined pigment is Chlorophyll B.

8. The system of claim 6 wherein the second predetermined pigment is carotenoid.

9. The system of claim 1 wherein the first predetermined pigment is Chlorophyll B;

and

the peak absorption wavelength of the first predetermined pigment is selected from a list consisting of 420 nm, 470 nm and 665 nm.

10. The system of claim 9 wherein the second predetermined pigment is Chlorophyll A.

11. The system of claim 9 wherein the second predetermined pigment is cartenoid.

12. The system of claim 1 wherein the first predetermined pigment is carotenoid;

and

the peak absorption wavelength of the first predetermined pigment is selected from a list consisting of 415 nm, 465 nm and 490 nm.

13. The system of claim 12 wherein the second predetermined pigment is Chlorophyll A.

14. The system of claim 12 wherein the second predetermined pigment is Chlorophyll B.

15. The system of claim 1 wherein the second predetermined pigment is Chlorophyll A;

and

the peak absorption wavelength of the second predetermined pigment is selected from a list consisting of 390 nm, 410 nm and 690 nm.

16. The system of claim 1 wherein the second predetermined pigment is carotenoid;

and

the peak absorption wavelength of the second predetermined pigment is selected from a list consisting of 420 nm, 470 nm and 690 nm.

17. The system of claim 1 wherein the second predetermined pigment is carotenoid;

and

the peak absorption wavelength of the second predetermined pigment is selected from a list consisting of 415 nm, 465 nm and 490 nm.

18. The system of claim 1 wherein a period of darkness in the predetermined periods of light and dark has a duration of 3.5 to 14.5 ms.