Circular polarization illumination device and plant growth regulation method

• US 9,848,540 B2
• Filed: 10/21/2013
• Issued: 12/26/2017
• Est. Priority Date: 04/22/2011
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Usami, Yoshihisa, Ichihashi, Mitsuyoshi, Takeuchi, Yohsuke
• Primary Examiner(s): Tsang, Lisa L
• Application Number:
  US14/058,992
• Publication Number:
  US 20140041295A1
• Time in Patent Office: 1,527 Days
• Field of Search: 47 101 R, 47 581 R, 47 581 LS, 47 581 SE, 47 581 FV, 362 19, 35948501, 35948503, 35948505, 35948701, 35948703, 35948704, 35948901, 35948907, 35948908, 35948911, 35948915, 35949001, 359599
• 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 9/14 for producing polarised light
• CPC Class Codes: Y02P 60/14 Measures for saving energy, e.g. in green houses

Abstract

The present invention provides a circular polarization illumination device which can irradiate right-circularly polarized light at a large light amount from a light source of right-circularly polarized light with a high efficiency and can irradiate left-circularly polarized light at a large light amount from a light source of left-circularly polarized light with a high efficiency, and a plant growth regulation method that can efficiently regulate the promotion or inhibition of the growth of plants by using the circular polarization illumination device. Moreover, the illumination device includes a light-emitting light source, a reflective polarizing plate, reirradiation unit, and circular polarization conversion unit.

Claims

1. A plant growth regulation method comprising irradiating a plant with a source of light irradiation,

wherein the source of light irradiation is a circular polarization illumination device,

the circular polarization device comprising:

a light-emitting light source;

a reflective polarizing plate that transmits one of a plurality of polarization components of incident light from the light-emitting light source and reflects a different one of the plurality of polarization components, wherein said one of the plurality of polarization components is p-polarized light, and said different one of the plurality of polarization components is s-polarized light;

a reirradiation unit for changing a polarization state of light reflected from the reflective polarizing plate to reirradiate the reflective polarizing plate with the light; and

a circular polarization conversion unit for converting light having been transmitted through the reflective polarizing plate into circularly polarized light,

wherein;

the reflective polarizing plate is any one of a total reflection-type polarizer, a polarizer as a laminate of thin films having different types of birefringence, a wire grid-type polarizer, a thin film-type polarizer, and a birefrigent polarizer;

the circular polarization conversion unit is a λ

/4 wave plate, and

plant growth is promoted by 20% or more if the plant is irradiated with right-circularly polarized light and plant growth is promoted by less than 20% if the plant is irradiated with left-circularly polarized light.

2. The plant growth regulation method according to claim 1, wherein the reflective polarizing plate is any one of a polarizer as a laminate of thin films having different types of birefringence or a wire grid-type polarizer.

3. The plant growth regulation method according to claim 1, wherein the reirradiation unit is any one of a diffusive reflector plate, a specular reflector plate, and a combination of a birefringent member and a reflector plate.

4. The plant growth regulation method according to claim 1, wherein the reirradiation unit is a combination of a birefringent member and a reflector plate.

5. The plant growth regulation method according to claim 4, wherein the reflector plate is any one of a specular reflector plate or a diffusive reflector plate.

6. The plant growth regulation method according to claim 1, wherein the light-emitting light source is a white lamp.

7. The plant growth regulation method according to claim 1, wherein the method comprises irradiating the plant with the source of light irradiation for 50% or more of a period from germination to harvest of the plant.