Apparatus and method for controlling plant growth with artificial light

• US 4,196,544 A
• Filed: 04/10/1978
• Issued: 04/08/1980
• Est. Priority Date: 04/10/1978
• Status: Expired due to Term

• Current Assignee: General Mills Incorporated
• Original Assignee: General Mills Incorporated
• Inventors: Davis, Noel, Dreier, William M., Davis, Noel B.
• Primary Examiner(s): Bagwill, Robert E.
• Application Number:
  US05/894,467
• Time in Patent Office: 729 Days
• Field of Search: 362/294, 362/336-337, 362/404, 362/406, 362/408-409, 47/17, 47/59, 47/62, 47/65, 47/DIG. 6
• US Class Current: 47/17
• CPC Class Codes: A01G 7/045 with electric lighting
• CPC Class Codes: A01G 9/246 Air-conditioning systems
• CPC Class Codes: A01G 9/249 Lighting means with special arrangements for promoting growth A01G7/045
• CPC Class Codes: F21V 29/56 using liquid coolants F21V29/51 takes precedence
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: Y02A 40/25 Greenhouse technology, e.g. cooling systems therefor
• CPC Class Codes: Y02P 60/14 Measures for saving energy, e.g. in green houses
• CPC Class Codes: Y10S 47/06 Plant growth regulation by control of light thereon

Abstract

In a chamber for cultivating plant growth, a plurality of light fixtures are employed, each containing a high intensity discharge lamp. The bulb of the lamp serves as an inner transparent wall and a globe functions as an outer transparent wall. In the space between the bulb and globe water is caused to flow in order to remove unwanted radiation and heat generated by each lamp before the radiation is transmitted into the growth chamber.

Claims

1. Apparatus for promoting plant growth comprising a growth chamber containing plants to be cultivated, at least one light fixture including a lamp for directing light onto said plants, said lamp including a bulb through which said light is directed, said bulb being oriented about a substantially vertical axis, said fixture further including a single outer globe through which light from the lamp is also directed, said globe being generally uniformly spaced from said bulb and mounted generally concentrically about said vertical axis, an inlet pipe connected to said fixture for introducing a liquid into the substantially uniform space between said bulb and globe at a first location near said bulb so that said liquid is in direct contact with said bulb to remove a substantial amount of the unwanted radiation produced in the generation of said light after said substantial amount of unwanted radiation has passed through said bulb so that said unwanted radiation does not pass through said globe into said growth chamber, and a discharge pipe connected to said fixture for removing said liquid and said unwanted radiation from between said same bulb and globe at a second location also near said bulb which said second location is spaced from said first location.

2. Apparatus in accordance with claim 1 in which said liquid also removes heat produced in the generation of said light.

3. Apparatus in accordance with claim 2 in which said liquid is water.

4. Apparatus in accordance with claim 3 in which said lamp has a neck and base, said base being uppermost, and sealing means extending between said neck and globe.

5. Apparatus in accordance with claim 1 including additional light fixtures mounted in said growth chamber in a spaced relation with said first light fixture and in a spaced relation with each other, each additional light fixture comprising a lamp for directing light onto other plants in said growth chamber, each additional lamp including a bulb through which light is directed, each of said additional bulbs also being oriented about substantially vertical axes, each additional fixture further including a single outer globe through which light from its lamp is also directed, each globe of said additional fixtures being generally uniformly spaced from the bulb of the fixture with which it is associated and mounted generally concentrically about the vertical axis about which its associated bulb is oriented, an inlet pipe connected to each of said additional fixtures for introducing a liquid into the substantially uniform space between the bulb for that fixture and the globe associated therewith at a first location near the bulb for that particular fixture in order that the liquid is in direct contact with its particular bulb to remove a substantial amount of the unwanted radiation produced in the generation of light after said substantial amount of unwanted radiation has passed through the particular bulb of a given fixture so that said unwanted radiation does not pass through the globe associated with that particular fixture into said growth chamber, and a discharge pipe connected to each of said additional fixtures for removing the liquid introduced into the fixture with which it is associated along with the unwanted radiation from between the bulb and globe associated with that particular fixture, said discharge pipe in each instance being located at a second location near the bulb with which it is associated but with the discharge pipe in each instance being located at a second location spaced from the first location for that particular fixture, and means for supplying liquid at substantially the same temperature to each of said inlet pipes so that substantially the same amount of unwanted radiation is removed from each fixture.

6. Apparatus for promoting plant growth comprising a growth chamber containing plants to be cultivated, at least one light fixture including a lamp for directing light onto said plants, said lamp including a vertically oriented bulb through which said light is directed, said lamp having a neck and base with said base being uppermost, said fixture further including a single outer globe through which light from the lamp is also directed, said globe being spaced from said bulb, sealing means extending between said neck and globe, a tube extending downwardly through said sealing means to introduce said liquid into said space at a location beneath said lamp, means for causing water to flow between said bulb and globe in direct contact with said bulb to remove unwanted heat produced in the generation of said light after said substantial amount of unwanted radiation has passed through said bulb so that said unwanted radiation does not pass through said globe into said growth chamber.

7. Apparatus for promoting plant growth comprising a growth chamber containing plants to be cultivated, a plurality of light fixtures for directing light onto said plants, each of said fixtures including inner and outer light transmissive walls through which said light is directed, means for causing a liquid to flow between said walls to remove a substantial amount of the unwanted radiation produced in the generation of said light, means for circulating air within said chamber, means for withdrawing some of the air from said growth chamber, first heat exchanger means for heating said fresh air as it enters said chamber, means for directing at least a portion of said liquid after it has passed between the inner and outer light transmissive walls of said light fixtures to said first heat exchanger means, means for sensing the air temperature within said growth chamber, means for controlling said first heat exchanger means in accordance with the temperature sensed by said sensing means to increase the temperature of said fresh air as it is introduced into said chamber, and second heat exchanger means outside of said chamber connected to said heat directing means so that liquid from said light fixtures can be directed to said second heat exchanger means when not needed by said first heat exchanger means.

8. Apparatus in accordance with claim 7 including third heat exchanger means for heating said fresh air as it enters said chamber, and an auxiliary means for supplying a heated medium to said third heat exchanger means when said lamp liquid is unable to heat said entering air to a desired temperature.

9. Apparatus in accordance with claim 8 including auxiliary cooling means for supplying a medium to said third heat exchanger means when said entering air is below said desired temperature.

10. Apparatus in accordance with claim 9 including means for adjusting the rate at which said fresh air enters said chamber.

11. Apparatus in accordance with claim 10 including means for sensing the dew point of said entering air, and means for controlling said adjusting means in accordance with the dew point sensed by said last-mentioned sensing means.

12. A method for promoting plant growth within a growth chamber comprising the steps of subjecting plants within said chamber to artificial light from a plurality of light fixtures, each light fixture having an inner and outer generally transparent wall, passing a radiation-absorbing liquid between said inner and outer walls at a sufficient flow rate to remove unwanted radiation from said light as said light is transmitted through said walls and liquid so as to prevent said unwanted radiation from being transmitted into said growth chamber, recirculating a substantial amount of air within said growth chamber, introducing a relatively small amount of fresh air into said chamber at a rate to control the humidity of the air being recirculated within said growth chamber, removing a portion of the air within said growth chamber in an amount and at a rate corresponding to the amount and rate at which said fresh air is introduced into said growth chamber, and maintaining a desired temperature of the air within said growth chamber by heating said fresh air being introduced into said growth chamber with at least some of said radiation-absorbing liquid after said liquid has passed between said inner and outer walls when said air being recirculated within said growth chamber is below a desired temperature.

13. Apparatus in accordance with claim 12 in which said globe is formed with a prismatic surface for refracting the light from said lamp downwardly onto said plants.

14. Apparatus for promoting plant growth comprising a growth chamber containing plants to be cultivated, a plurality of light fixtures for directing light onto said plants, each of said fixtures including a single inner and a single outer light transmissive wall through which said light is directed, said inner and outer walls being oriented about a substantially vertical axis, means for causing a liquid to flow between said walls to remove a substantial amount of the unwanted radiation produced in the generation of said light, means for recirculating air within said chamber, means for introducing fresh air into said chamber, means for adjusting the rate of fresh air introduced into said chamber to control the humidity of the air being recirculated within said growth chamber, means for removing air from said growth chamber at the rate that air is introduced into said growth chamber, and means for controlling the temperature of the air being introduced into said growth chamber to maintain a desired temperature of the air being recirculated within said growth chamber.

15. Apparatus in accordance with claim 14 in which said temperature controlling means includes a heat exchanger in the path of said fresh air as it enters said chamber.

16. Apparatus in accordance with claim 15 including means for directing at least a portion of said liquid after it has passed between the inner and outer light transmissive walls of said light fixtures to said heat exchanger when the temperature of the air being recirculated within said growth chamber is below said desired temperature.

17. Apparatus in accordance with claim 15 including means for directing a cooling medium to said heat exchanger when the temperature of the air being recirculated within said growth chamber is above said desired temperature.