Greenhouse illumination system

• US 5,095,414 A
• Filed: 06/07/1991
• Issued: 03/10/1992
• Est. Priority Date: 06/07/1991
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Department Of Agriculture
• Inventors: Tinus, Richard W.
• Primary Examiner(s): Husar, Stephen F.
• Application Number:
  US07/712,226
• Time in Patent Office: 277 Days
• Field of Search: 47/DIG. 6, 362/276, 362/277, 362/282, 362/284, 362/322, 362/324, 362/805, 362/35
• US Class Current: 362/284
• 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: F21V 14/04 by movement of reflectors in vehicle head lamps F21S41/675
• CPC Class Codes: F21V 17/02 with provision for adjustment F21V17/04 - F21V17/08 take precedence
• CPC Class Codes: Y02P 60/14 Measures for saving energy, e.g. in green houses
• CPC Class Codes: Y10S 362/805 Horticultural
• CPC Class Codes: Y10S 47/06 Plant growth regulation by control of light thereon

Abstract

An improved single light fixture for use in intermittently illuminating plants in a greenhouse. A bulb of a particular selected light output frequency is selected, and the fixture comprises an oscillating parabolic mirror which sweeps the light from the bulb across all of the plants in the greenhouse.

Claims

1. A method of providing light intermittently to plants growing in a greenhouse comprising the steps of:

selecting a light bulb having a predetermined output spectrum;

providing a single light fixture;

mounting said bulb in said light fixture so that said bulb does not move in use;

providing a heat resistant parabolic mirror in said fixture;

locating said bulb at the focal line of said mirror;

mounting said fixture centrally in said greenhouse;

causing said mirror to oscillate about its focal line through a predetermined angle; and

selecting said angle such that the light from said bulb is swept over substantially all of the plants in said greenhouse.

2. The method of claim 1, selecting a high pressure sodium arc light as said light bulb.

3. The method of claim 1, and oscillating said mirror at a speed in the range of at least two to about 60 complete cycles of oscillation per hour.

4. The method of claim 1, and selecting the wattage of said light bulb in accordance with the size of said greenhouse.

5. The method of claim 1, wherein said greenhouse has dimensions on the order of 20 feet wide by 50 feet long, mounting said fixture in said greenhouse above normal head level of people walking and working in said greenhouse, and said light bulb comprises an elongated high-pressure sodium arc lamp of 400 watts power.

6. The method of claim 1, wherein selecting said predetermined angle of mirror oscillation to be relatively close to but less than about 180°

.

7. The method of claim 1, providing control means and lamp ballast means for said light fixture, and mounting said control means and said ballast means externally of said greenhouse.

8. A light fixture for providing light intermittently to plants growing in a greenhouse, comprising frame means, a light bulb of a predetermined light output spectrum, parabolic mirror means, means to mount said mirror means on said frame, means to cause oscillating motion of said mirror means with respect to said frame means about the focal line of said mirror means, and means to mount said light bulb on said frame means at the focal line of said mirror means, and so that said light bulb does not move with respect to said mirror means.

9. The fixture of claim 8, said mirror means consisting essentially of polished stainless steel.

10. The fixture of claim 8, wherein said greenhouse has dimensions on the order of 20 feet wide by 50 feet long, means to mount said fixture in said greenhouse above normal head level of people walking and working in said greenhouse and centrally of said greenhouse, and said light bulb comprising an elongated high-pressure sodium arc lamp of 400 watts power.

11. The fixture of claim 8, said means to cause oscillatory motion comprising a gear motor, means to mount said gear motor on said frame, linkage means interconnecting said gear motor with said mirror means, and the speed of said gear motor together with the dimensions and configuration of said linkage causing said mirror means to oscillate at a speed in the range of at least 2 to about 60 complete cycles of oscillation per hour.

12. The fixture of claim 11, said linkage means including means to control the total arc of swing of said mirror means about its focal line.

13. The fixture of claim 11, said linkage including speed change gear means, said linkage including a crankshaft driven by said gear motor and means connecting the output of said crankshaft to the input of said speed change gear means, and said linkage being such that the speed of oscillation of said mirror means matches the speed of rotation of said gear motor.

14. The fixture of claim 8, means to mount said light fixture in a greenhouse centrally therein, control means and lamp ballast means for said light fixture, and means to mount said control means and said ballast means externally of said greenhouse.

15. The fixture of claim 14, said control means including a control circuit of said lamp ballast means, said gear motor;

and a manual switch.

16. The fixture of claim 14, said control means including a control circuit of said lamp ballast means, said gear motor, and a 24 hour time means.

17. The fixture of claim 14, said control means including a control circuit of said lamp ballast means, said gear motor, and a normally closed photocell means.