RU2575016C2 - Optical device, lighting device and system for lighting crown cover of plants - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to lighting engineering. The first rational quadratic Bezier curve and the second quadratic Bezier curve are selected independently from each other and are placed so that optical device is asymmetric in regard to its central axis of rotation. Upon reflection in the first plane the received light is reflected in direction to the central axis and upon reflection in the second plane the received light is reflected in direction from the central axis thus ensuring asymmetric vertical distribution of intensity at output from the optical device so that in the preset area lighted under angle vertical and horizontal distribution of illumination is provided.

EFFECT: increased efficiency of crown cover of plants, which is attained due to the optical device (100) having the light input area (109) for receipt of light from the light source, the first surface (120) described by the first rational quadratic Bezier curve and the second surface (110) described by the second rational quadratic Bezier curve.

21 cl, 8 dwg

Description

Technical field

The present invention relates to an optical device, a corresponding lighting device, and to an illumination system of a leaf canopy of plants, and more particularly, to a lighting system of a leaf canopy of plants that provides uniform vertical and horizontal distribution of illumination in a predetermined target area of the plant.

Prior level

To increase productivity in greenhouses, the absorption of additional light is used along with natural sunlight. In particular, high intensity discharge lamps (HID lamps), such as SON-T, with an electric power of 600-1000 W are used. As a result, the level of illumination in the greenhouse rises, which increases the yield per square meter of the area of the greenhouse compared with greenhouses that work only in sunlight. However, plants such as tomatoes or cucumbers grow to a height of several meters. In this case, the upper leaves, located closer to the light source, absorb most of the incident light. The shadow zone formed in this way leads to less efficient photosynthesis in the lower leaves and, consequently, to lower productivity. To further increase productivity per square meter of the greenhouse, additional light sources illuminate the plants in the shade area. This lighting concept is known as intercanopy lighting.

Effective illumination of the canopy is usually realized by illuminating the plants in the vertical zone, which begins in the lowest part of the plant where the leaves develop and ends about 0.5 m below the top of the plant. The light reaching the parts of the plant outside this vertical zone is either lost in the direction of the ground or ceiling, or reaches those parts of the plant that are already adequately illuminated by lamps located above the plant.

Typically, inter-leaf canopy illumination is accomplished by placing HID lamps between rows of plants, such as tomatoes or cucumbers, at a predetermined distance from a row of plants, typically between 04 and 1.0 m, and the distance between adjacent lamps is 1.9 m. Such geometric conditions, in combination with the Lambertian light distribution of such lamps, give a highly variable horizontal and vertical irradiation of the plant surface. Further, the placement of lamps between rows of plants to illuminate the canopy blocks the working area, which should be accessible for greenhouse workers.

Retractable HID-lamp systems are known in which lamps are temporarily diverted to free the work area for workers to access. Therefore, the lamps must be returned to the place to illuminate the inter-leaf canopy of plants.

SUMMARY OF THE INVENTION

The present invention is to eliminate the problems of the prior art, as described above, and the creation of an alternative and improved optical device, a lighting device and a system for illuminating the leaf canopy of plants in a greenhouse. Another objective of the present invention is to create a vertical and horizontal uniform distribution of lighting in a predetermined target area when the target area is illuminated at an angle.

The present invention provides an optical device, a lighting device, and an inter-leaf canopy lighting system that creates an asymmetric lighting pattern with respect to the vertical and horizontal directions.

According to a first aspect of the present invention, these and other objectives are achieved by using an optical device for illuminating a canopy containing a light entrance region for receiving light from a light source, a first surface having a first Bezier curve, and a second surface having a second Bezier surface. The first and second Bezier curves are selected independently from each other and arranged so that the optical device is not axisymmetric with respect to the central axis. The received light, which is reflected by the first surface, is reflected in the direction to the central axis, and the received light, which is reflected by the second surface, is reflected in the direction from the central axis, thereby providing a vertical and horizontal uniform distribution of lighting in a predetermined area that is illuminated at an angle.

Thus, an optical device for creating collimation and asymmetric light distribution is proposed, which is advantageous and positioned to create an asymmetric light intensity distribution in two directions. Firstly, the optical device is positioned so that the width of the vertical and horizontal distribution of the light exiting the optical device is substantially different. The vertical distribution of the radiation intensity can be chosen so that it is narrow and, at the same time, the horizontal radiation intensity can be chosen so that it is wide, which provides advantages for illuminating the inter-leaf canopy of plants in the desired and specific area, a predetermined area, which is called the target area . In particular, the target zone is determined by the total width of the plant and part of its height, starting from a specific minimum distance from the ground. Secondly, and at the same time, the vertical distribution of the radiation intensity is asymmetric, i.e. more light can be directed down than up. In this way, a horizontal uniform distribution of the radiation intensity in a predetermined target area is achieved when illuminated at an angle. This gives advantages in creating lighting that must meet the criterion of uniformity of plant lighting.

According to a variant of the optical device, the first and second surfaces reflect light by total internal reflection. Due to this, the optical device is mainly compact.

According to an embodiment of the optical device, the optical device comprises an optical element located in the light entrance region. This optical element is a lens in the form of a truncated cone, the base of which is located in the area of the entrance of light. The truncated apex of this cone is concave. Thus, the optical element is positioned so that the light entering the optical element and moving towards the output surface is collimated, and the light moving towards the sides of the optical element is directed to the first and second surfaces. Due to this, the efficiency of the optical device increases, since the light entering through the input region is collimated for more efficient distribution towards the output face of the optical device. This ensures that there is no light on the first and second surface after the lens. Thus, the light, which otherwise would be scattered in the vertical direction, enters the target zone.

According to a variant of the optical device, it contains an optical element located in the light entry zone and designed to asymmetrically redirect the received light due to the fact that the element contains an asymmetric section of free shape, or a displaced section of a cylindrical shape, or a section of an elliptical shape, or an inclined section of an elliptical shape.

According to a second aspect of the present invention, there is provided a lighting device for illuminating an inter-leaf canopy of plants, comprising at least one light source located on a substrate, and an optical device according to the present invention. The optical device is configured to receive light from at least one light source. A predefined area is a predetermined target area of the plant. This ensures a vertical and horizontal uniform distribution of lighting in the target area of the plant. Due to the asymmetric distribution of light intensity in two directions, as described above for the optical device, the first and second surfaces can be chosen so that the target area receives uniform illumination, even when illuminated at an angle.

According to an embodiment of the lighting device, the height of a predetermined target area for young plants is selected to cover 100% of the plant height. For fully grown plants, the height of the predetermined target zone is chosen so that it covers 10-50% of the plant height, which is preferred to increase yield.

According to a variant of the lighting device, the substrate is made mirror-like. This allows you to efficiently redirect recycled light back to the plant.

According to a variant of the lighting device, the substrate contains a reflective layer of metal, which increases the optical efficiency. The metal layer can be made of any suitable metal, for example aluminum, silver, etc.

According to an embodiment of the lighting device, the substrate has a flat or parabolic or conical shape, a combined flat shape with flat inclined walls, a combined flat shape with parabolic walls, or a combined flat shape with walls in the form of a Bezier surface. Giving the appropriate shape to the substrate increases the optical efficiency, which is an advantage.

According to an embodiment of the lighting device, the light source is a light emitting diode. The lighting device is mainly used to limit the light emitted by light emitting diodes to a narrow zone, which is called the target zone. To create light suitable for illuminating the inter-leaf canopy of plants, light emitting diodes of medium or high power are preferably used.

According to an embodiment of a lighting device, a plurality of light sources are used in the device. The light sources are arranged to emit a combination of red and blue light or a combination of red and white light. Depending on the type of plants, 5-20% of the optical power that reaches the plant should be blue. In particular, the light sources are distributed in the lighting device so that upon reaching the plant, the plurality of colors are completely mixed.

According to a third aspect of the invention, there is provided a system for illuminating an inter-leaf canopy of plants. The system comprises a plurality of lighting devices according to the present invention, means for installing lighting devices at a specific height h ₀ and at a predetermined horizontal distance d ₀ relative to a predetermined target area of the plant so that the lighting devices are arranged so as to create a uniform and directed beam for lighting a predetermined target zone of plants.

According to a variant of the system, the height of a predetermined target zone is selected in the range of 10-50% of the height of a fully grown plant and 100% for young plants.

According to a variant of the system, the horizontal distance d _{0 is} advantageously chosen in the range of 1.0-3.0 m, since this distance provides a sufficient working area for the personnel of the greenhouse.

According to a variant of the system, the system is mounted movably so that its height can be changed.

It should be noted that the invention relates to all possible combinations of features given in the claims.

Brief Description of the Drawings

These and other aspects of the present invention are described in more detail below with reference to the accompanying drawings, illustrating embodiments of the invention, in which:

Figure 1 - schematic representation of a variant of the optical device in section according to the invention;

Fig. 2a is a schematic cross-sectional side view of an embodiment of a lighting device according to the present invention;

Fig.2b is a schematic top view in section of a variant of the lighting device of Fig.2A;

Figa is a schematic side view in section of a variant of the lighting device according to the present invention;

Fig. 3b is a schematic top view of an embodiment of a lighting device according to the present invention;

FIG. 4a-4c are schematic side views illustrating a lighting system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following is a more complete description of the variants of the present invention with reference to the attached drawings, which show some variants of the invention. The invention, however, can be implemented in many different forms and should not be construed as limited to the options described herein. These options are given as an example for completeness and accuracy of the description and fully define for specialists the scope of the present invention. In all the drawings, like elements are denoted by like reference numerals.

In the following description, optical efficiency is defined as the amount of light reaching the plant relative to the amount of light emitted by the light source used to illuminate the target area of the plant. The width (i.e. horizontal extent) of the target zone is any typical width of a number of plants in the greenhouse, i.e. it can be from 5 m to 70 m. Further, any of the light sources mentioned below is represented by light emitting diodes. However, within the scope of the present invention, any other light source is applicable.

The uniformity in this application is defined as follows. In the target zone, you can find the minimum illumination E _min and maximum illumination E _max for both the vertical section and the horizontal section. For both sections, the uniformity corresponds to the ratio (E _min / E _max ) _v, h≥0.7 (v - vertical, h - horizontal).

1 shows an optical device 100 with a light entrance region 109 and a light exit region 111. The optical device 100 is centered along the optical axis o.a. The optical device 100 has a first surface 120 extending from the light entrance region 109 to the light exit region 111. The first surface 120 has a shape defined by a first Bezier curve. The optical device 100 has a second surface 110 extending from the light entrance region 109 to the light exit region 111. The second surface 110 is defined by a second Bezier curve. The first and second Bezier curves are selected independently of each other. The first surface 120 and the second surface 110 are surfaces that are described by rational quadratic Bezier curves. This means that each curve is described by a starting point P ₀ , an end point P ₂ and a control handle-manipulator P ₁ , which does not lie on a straight line connecting the points P ₀ and P ₂ . For an optical device, 100 P ₀ determines the initial radius, and P ₂ determines the final radius. Point P ₁ determines the curvature. In addition, in the rational Bezier curve used, two weight parameters are used, which lie in the range from 0 to 1. Thus, there is greater freedom of choice of possible curvature. The first surface 120 and the second surface 110 are arranged so that the optical device 100 is not axisymmetric with respect to the central axis.

The light entrance region 109 is arranged to receive light from a light source, which is preferably located adjacent to the light entrance region. As shown by the light beam B in FIG. 1, the Bezier curve of the first surface 120 is selected so that the received light reflected by the first surface 120 is reflected in the direction of the central axis. Next, the Bezier curve of the second surface 110 is selected so that the received light is reflected by the second surface 110 in the direction from the central axis, as shown in FIG. 1 light beam A.

In FIG. 2a and 2b, a lighting device 200 is shown having a small light source, such as a light emitting diode 101, which is mounted on a substrate 103 and is located adjacent to the light input region 109 of the optical device 100 '. The light emitting diode 101 emits a diverging light beam in the direction of the light entrance region 109, and the light received in the optical device 100 'is collimated by an optical element that is mounted in the optical device. The optical element is a collimator 102 located in the light input region 109. The collimator 102 is arranged as a lens in the form of a truncated cone, the base of which is located in the light entrance region 109 or, alternatively, is the light entrance region. The truncated apex of the lens is concave.

The first part of the light emerging from the collimator 1-2 on the side of the cone falls on the first surface 120 (cf. beam A in FIG. 1) and is reflected due to total internal reflection in the direction from the central axis, and then leaves through region 111 light exit. The light moving in the forward direction, essentially along the optical axis of the device, that is, to the light exit region 111 or to the output face of the device, is collimated by the collimator 102. The light exiting towards the first surface 110 and the second surface 120 is not collimated. Therefore, in the end, the collimator 102 reduces the angular divergence of the light directed forward, which is not reflected by the first and second surfaces 110, 120 and which, otherwise, would not be collimated, while it affects the lateral angular divergence.

The first light beam and the second light beam have different light intensity distributions (cf. A and B in Fig. 1) and the total intensity distribution of the light exiting the light exit region 111 is an overlap of the first and second parts of the light (and, in addition, any light exiting from the optical device 100 'without being reflected from the first or second surface). The light is output in the form of a uniform and directional beam, which can, for example, cover a predetermined target zone of plants. The resulting distribution of radiation intensity (lm / sr) in the vertical direction differs significantly from the distribution of radiation intensity in the horizontal direction. Additionally, this design allows you to create a vertical intensity distribution of the radiation, which in itself is asymmetric in the sense that more light is directed to the lower part of the target zone than to the upper part, or vice versa, depending on the chosen orientation of the optical device.

In alternative embodiments, the optical element is arranged to asymmetrically redirect the light from the light source. This can be done using an aspherical lens (not shown) in the truncated part of the collimator.

The substrate 103 in the variants of the lighting device 200 is made by applying to the substrate a mirror-reflecting material or a reflective layer, for example a metal layer. Thus, light that would otherwise be lost, for example, by scattering backward, is reflected by the substrate and reused, as it is redirected to the surface of the plant when the lighting device is used to illuminate the inter-leaf canopy of the plant. Calculations show that using an aluminum (Al) layer with 85% reflection, 90% optical efficiency can be obtained for the system described below with reference to FIG. 4a-4c. Further, the shape of the substrate is advantageously such as to increase the optical efficiency. FIG. 3 a shows a lighting device 300 having a parabolic substrate 104 that collimates to some extent. Calculations show that when using such a substrate 104 with a small collimation, the optical efficiency can exceed 90% for the system described below with reference to FIG. 4a-4c. FIG. 3b shows another lighting device 400 in which the substrate has a flat base 105 with flat sloping walls 106 designed to reflect light to the target area. Other possible substrate shapes may be a conical shape in combination with parabolic walls and a flat shape in combination with walls having the shape of a Bezier curve (not shown).

One or more lighting devices according to the present invention can be combined into a lighting device (not shown). You can use light sources of different colors, which is preferred for illuminating the inter-leaf canopy of plants. Typically, red and blue or red and white light emitting diodes are used. Lighting devices expand the light flux in the horizontal direction so that the light emitted by blue and red or white and red light-emitting diodes distributed over the substrate is mixed on the plant. Typically, 5% to 20% of the light emitted from the plant should be blue.

In the greenhouse, controlled cultivation or plant protection occurs. As shown in FIG. 4 a, a greenhouse traditionally has two lighting sources, solar and overhead lighting 60, which is usually represented by HID lamps mounted on the ceiling. Further, to illustrate the concept of the present invention in FIG. 4a-4c show the general principle of an embodiment of a system for illuminating an inter-leaf canopy of plants with possible positions of a lighting device (or lighting device, as described above) in a greenhouse. The system typically comprises a plurality of lighting devices or lighting fixtures 600 that are arranged in a position determined by a predetermined height h ₀ to illuminate the target area of plants 50, which are typically arranged in rows on beds 20. Here, one lighting fixture 600 contains a plurality of lighting devices, each of which there is one light emitting diode of an acceptable color, usually so that a mixture of red and blue or white and red is obtained on the surface of the plant. A predetermined height h _{0 is} calculated in the direction of light from the lighting device. 4 a, the lighting fixture 600 distributes the light at an approximately 28 degree angle downward, which necessitates the installation of the lighting fixture above the target zone, which is determined by the lower height limit h ₂ and the upper height limit h ₁ . Here, the angle of illumination is selected as 28 degrees down, however, the selected angle of illumination is typically based on a particular plant type and stage of plant growth. The height of the target zone, i.e. h ₁ -h ₂ are usually selected in the range of 10-50% of the height of a fully grown plant and 100% for young plants. In the first case, the predetermined height is h ₀ > h ₁ .

The lighting device is located at a horizontal distance d ₀ from the target area, which is selected so that the lighting device 600 is located outside the working area WA for the personnel of the greenhouse. Due to the asymmetric shape of the lighting devices in the lighting fixture 600, the light is efficiently directed to the target zone starting at a height h ₁ above the ground and ending at a height h ₂ . Thus, the target area of the plant is irradiated at a vertical angle, which in this case is about 28 degrees down. Another example is shown in FIG. 4b, where the target zone is irradiated at a vertical angle of about 45 degrees up. The vertical angle can be equal to or greater than 0 degrees (0 degrees means that the direction of irradiation is parallel to the normal to the target area, as shown in figs).

In the case of tomatoes, h ₁ is about 1.5-2.9 m, and h ₂ is about 1 m, as a result, the target zone in the vertical direction has a size of 0.5-1.0 m. Under these conditions, the system in which Lighting devices that do not have a reflective substrate and are located as shown in FIG. 4 can illuminate the target area with an optical efficiency of about 70%. As described above, the illumination efficiency of the target zone can be significantly increased using a reflective substrate, which optionally can be given the appropriate shape.

The typical distance between the lighting device and the target area is 0.5-1.5 m (in the horizontal direction). A typical installation height of a lighting device is about 2.0 m, however, other installation positions of lighting devices can be used to obtain different vertical angles of illumination of lighting devices / appliances, as described above. In order to avoid light loss in other parts of the plant in the vertical direction, strong collimation is required. Given the above parameters for the above system, a typical target area corresponds to a beam width in the vertical direction from the lighting device / device, equal to about 20 degrees.

Variants of an optical device, a lighting device, and a system of the present invention, as defined in the appended claims, which are merely non-limiting examples, have been described above. Those skilled in the art will appreciate that various changes and alternatives are within the scope of the invention.

It should be noted that for the purposes of this application and, in particular, the attached formula, the word “comprising” does not exclude the presence of other elements or steps, and the singular form does not exclude the plural, as is obvious to those skilled in the art.

Claims (15)

1. An optical device (100) for illuminating a canopy of plants containing
a light entrance region (109) for receiving light from a light source,
the first surface (120) described by the first rational quadratic Bezier curve, and
the second surface (110) described by the second rational quadratic Bezier curve,
the first and second rational quadratic Bezier curves are selected independently from each other, and these surfaces are arranged so that the optical device is asymmetric with respect to its central axis of rotation, while
the received light reflected in the first plane is reflected towards the central axis, and the received light reflected in the second plane is reflected towards the central axis, thereby providing an asymmetric vertical intensity distribution at the exit of the optical device, so that in a predetermined region , which is illuminated at an angle, provides a vertical and horizontal uniform distribution of illumination. 2. The device according to claim 1, in which the first and second surfaces reflect light through total internal reflection. 3. The device according to claim 1 or 2, further comprising an optical element located in the light entrance region, the optical element being a truncated cone lens, the base of which is located in the light entrance region, and the truncated lens apex is concave. 4. The device according to claim 1 or 2, further comprising an optical element located in the light entry region, wherein the optical element is arranged to asymmetrically redirect the received light due to the presence of one of the asymmetric free-form portion, the displaced portion of the cylindrical shape, the portion of the elliptical shape or inclined plot of elliptical shape. 5. A lighting device for illuminating an inter-leaf canopy of plants, comprising:
at least one light source located on a substrate, and
an optical device having a first surface described by a first rational quadratic Bezier curve and a second surface described by a second rational quadratic Bezier curve, the first and second rational quadratic Bezier curves being selected independently from each other, and the surfaces are arranged so that the optical device is asymmetric with respect to its central axis of rotation, while the received light reflected in the first plane is reflected towards the central axis, and the received light reflected in the second a swarm of the plane is reflected in the direction from the central axis, thereby providing an asymmetric vertical distribution of the intensity of the light exiting from the optical device, so that in a predetermined area that is illuminated at an angle, a vertical and horizontal uniform distribution of illumination is provided,
wherein the optical device is positioned to receive light from said at least one light source, and the predetermined area is the predetermined target area of the plant. 6. The device according to claim 5, in which the height of the predefined target zone for young plants is selected so as to cover 100% of the plant height, and for fully grown plants, the height of the predefined target zone is selected so as to cover 10-50% of the plant height. 7. The device according to claim 5 or 6, in which the substrate is mirror reflective. 8. The device according to claim 7, in which the substrate contains a reflective layer of metal. 9. The device according to claim 7, in which the substrate has a shape selected from flat, parabolic, conical, flat in combination with inclined flat walls, flat in combination with parabolic walls or flat in combination with walls having the shape of a surface described by a rational quadratic Bezier curve. 10. The device according to claim 5 or 6, in which the light source is a light emitting diode. 11. The device according to claim 5 or 6, wherein a plurality of light sources are used, the light sources being arranged to emit a combination of red and blue light or a combination of red and white light. 12. A system for illuminating an inter-leaf canopy of plants, comprising:
many lighting devices according to any one of paragraphs. 5-11,
means for installing these lighting devices at a predetermined height h ₀ and at a predetermined distance d ₀ relative to a predetermined target area of the plants, so that
Lighting devices provide a uniform and directed beam of light near a predetermined target zone of plants. 13. The system of claim 12, wherein the height of the predetermined target zone is 10-50% of the height of a fully grown plant and 100% of a young plant. 14. The system according to p. 12 or 13, in which the horizontal distance d _{0 is} selected in the range of 1.0-3.0 m 15. The system according to p. 12 or 13, in which the system is mounted movably with the possibility of raising and lowering.

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