RU106934U1 - LIGHTING DEVICE - Google Patents

Abstract

 1. A lighting device comprising a fiber guide element made of an elongated shape and having at least one longitudinal section of the base and two sides tapering from the base to the top, the base of each of said longitudinal sections being located at the end of the fiber guide element, and a directional light source located at the end of the light guide element for directing the light flux to this end, the angle between the direction of the light flux from the directional light source and directed the extension length of the light guide member is selected in such a range that the light flux experiences at least one total internal reflection from said tapering sides in said at least one longitudinal section of the light guide member and exits through one of these tapering sides after at least one of said total internal reflections. ! 2. The device according to claim 1, in which the refractive index of the material of the light guide member, as well as the limits of the angles between said tapering side sides in those of said longitudinal sections in which the light flux propagates, and said range of angles at which the light flux enters the light guide member is selected so that the light flux exits through the same of the tapering sides. ! 3. The device according to claim 2, in which the light guide element is made curved so that in at least one of the aforementioned longitudinal sections, in which the light flux propagates in the light guide element, a smoothly narrowing figure with a bulge in �

Description

The technical field to which the utility model relates.

This utility model relates to lighting equipment, in particular, to a lighting device, which allows to obtain economical, comfortable for the perception of the eye, uniform light flux when using LED light sources for lighting residential, technological and technical rooms.

State of the art

Light devices are currently known in which LED light sources are used, in which diffuse light scattering is used to provide a more uniform light flux. See, for example, RF patents for utility model No. 95886 (publ. 10.07.2010) and No. 93929 (publ. 10.05.2010), as well as application for US patent No. 2011/0042700 (publ. 24.02.2011).

The disadvantage of such technical solutions is the presence of scattering particles in the material of the light guide element transmitting light from the LEDs.

Also known is the focusing of the luminous flux with various lenses, as, for example, in the patent of the Russian Federation for utility model No. 95181 (published on June 10, 2010). However, such focusing, although it does not use light-scattering particles in the material of the light guide element, is not able to provide uniform illumination due to distortions (aberrations) inherent in any lens.

Utility Model Disclosure

Thus, the purpose of this utility model is to provide:

- the conversion of light beams from sources into one or more outgoing light beams of a larger cross section;

- a more uniform brightness of the emerging beams over the cross section;

- high efficiency in input-output of light radiation; and

- a given direction (directions) of the emerging beams.

To achieve the above goal, the object of this utility model proposes a lighting device containing a light guide element made of an elongated shape and having at least one longitudinal section of the base and two sides tapering from the base to the top, with the base of each of the longitudinal sections at the end of the light guide element, and a directional light source located at the end of the light guide element to direct the light flux to this end, the angle between the direction the luminous flux from the directional light source and the extension direction of the light guide member is selected in such a range that the light flux experiences at least one total internal reflection from said tapering sides in at least one longitudinal section of the light guide member and exits through one of these tapering sides after at least one of the total internal reflections.

A feature of the lighting device according to this utility model is that the refractive index of the material of the light guide element, as well as the limits of the angles between the tapering sides in those longitudinal sections in which the light flux propagates, and the range of angles at which the light flux enters the light guide element, can be selected so that the luminous flux exits through the same of the tapering sides.

Another feature of the lighting device according to the present utility model is that the light guide element can be made curved so that in at least one of the longitudinal sections in which the light flux propagates in the light guide element, a smoothly tapering figure is formed with a bulge to the side light output from the light guide member.

In this case, the light guide element can be made in the form of a smoothly curved plate obtained by parallel transfer of a smoothly tapering figure in the direction perpendicular to the plane of this figure, and many directional light sources can be placed at the end of the light guide element. Or the light guide element can be made in the form of a body of revolution, obtained by rotating a smoothly tapering figure around an axis lying in the plane of this figure and outside this figure near its sharp end, and many directional light sources can be placed at the end of the light guide element.

Another feature of the lighting device according to the present utility model is that the light guide element can be made curved so that in at least one of the longitudinal sections in which the light flux propagates in the light guide element, a multilateral tapering figure is formed, limited by broken lines having a bulge towards the exit of the light flux from the light guide element.

In this case, the light guide element can be made in the form of a plate bent with kinks, obtained by parallel transfer of a multilateral tapering figure in the direction perpendicular to the plane of this figure, and a lot of directional light sources can be placed at the end of the light guide element. Or, the light guide element can be made in the form of a body of revolution obtained by rotating a multilateral tapering figure around an axis lying in the plane of this figure and outside this figure near its sharp end, and many directional light sources can be placed at the end of the light guide element.

Another feature of the lighting device according to this utility model is that directional light sources can be placed uniformly at the end of the light guide element.

Finally, another feature of the lighting device according to the present utility model is that an LED can be used as at least one directional light source.

Brief Description of the Drawings

The utility model is illustrated in the accompanying drawings.

1 is a cross-sectional view of a light guide member in accordance with one embodiment of the present utility model.

Figure 2 shows the pattern of propagation of rays in an ellipse with the ratio of the lengths of the axle axles a / b = 2.

Figure 3 illustrates the initial distribution of the light flux from a point source.

Figure 4 shows the proportion η of radiation emerging from the ellipse depending on the angle φ of the tilt of the light beam relative to the axis connecting the foci of the ellipse; points 1–4 are shown, which correspond to the tilt angles at which 15% of the total source power goes out.

Figure 5 shows the sections A ₁ B ₁ and A ₂ B _{2 of the} surface of an elliptical lens made of glass, through which 0.15 of the source power in focus 1 comes out.

6 is a diagram of the construction of the plot And ₂ In _{2 the} lower (non-working) surface of the light guide element with total internal reflection; the tricks 1 of the large and small ellipses coincide.

Fig.7 shows the angles of incidence of the beam on the surface And ₂ In ₂ in Fig.6.

Fig. 8 illustrates the angular distribution functions of the light beam in the light guide member of Fig. 6.

Fig.9 gives a conditional view of a light guide element with a fixed power (15% of the total) emerging at each reflection of the light beam from the upper (working) surface, if radiation does not exit through the lower surface (angular relations are stored exactly) according to the present utility model.

FIG. 10 shows the initial (0) and angular distribution functions after each reflection 1-11 in the light guide member of FIG. 9.

11 shows a light guide member according to a possible embodiment of the present utility model.

Detailed Description of Embodiments of a Utility Model

A lighting device according to the present utility model comprises a light guide member and at least one directional light source. To begin with, we consider a light guide element with the sides (11) tapering from the base in a cross section, which is conventionally shown in FIG. This can be a wedge-shaped or cone-shaped light guide element, that is, made of elongated shape and having a base in at least one longitudinal section and two sides tapering from the base to the top, with the base of each of the said longitudinal sections being located at the end of the light guide element.

In a light guide element with a cross section in FIG. 1, a beam from a light source (12) located at the end of the light guide element to direct the light flux to this end and having an angle θ relative to the longitudinal axis of the light guide element experiences a first reflection at an angle φ ₁ = π / 2-θ-α / 2, from the left working surface of the fiber and passes further. After the second reflection (reflection from the right working surface) φ ₂ = π / 2-θ-3α / 2, after the k-th reflection the angle will be equal to φ _k = π / 2-θ-α (k-1/2), t .e. φ _k decreases with each reflection. Thus, with some reflection k _* (θ) (in Fig. 1 k _* (θ) = 2) it turns out that where φ _* is the angle of total internal reflection for the fiber material with a refractive index n. Upon reflection of k _* and subsequent light starts to go out of the fiber. Thus, at the initial stage of the propagation of light, for k <k _* (θ), it is transported along the extension direction of the fiber without going outside, and then, for k≥k _* (θ), the radiation is transmitted and exited. The rays of the source with a large angle θ relative to the longitudinal axis of the fiber will exit closer to the input end of the fiber, and rays with a smaller θ will be farther from this end.

That is, the angle between the direction of the light flux from the directional light source and the extension direction of the light guide member is selected in such a range that the light flux experiences at least one total internal reflection from said tapering sides in said at least one longitudinal section of the light guide member and exits through one of these tapering sides after at least one of said total internal reflections. Thus, they ensure uniform output of radiation from the side surfaces of the fiber.

If now the refractive index of the material of the light guide element, as well as the limits of the angles between the tapering sides (11) in those longitudinal sections where the light flux propagates, as well as the range of angles at which the light flux enters the light guide element, choose so that the light flux out through the same of the tapering sides (11), you get a light guide element with radiation from only one side. The specified selection of the refractive index and the corresponding angles is a rather complicated task, which in each case is solved using mathematical modeling.

The light guide element shown in FIG. 1 can be bent so that at least in one of the longitudinal sections where the light flux propagates in the light guide element, a smoothly tapering figure is formed with a bulge towards the exit of the light flux from the light guide element.

Let us now consider the case when the curved lines in the longitudinal section of such a light guide element are segments of ellipses. For simplicity, we first turn to Figure 2, where a point source of light (12) giving a luminous flux within an angle of 2θ ₀ is placed at one of the focal points of the ellipse. The ellipse is made of a material with a refractive index n ₁ , outside is a material with a refractive index n ₂ <n ₁ . The direction of the source beam (12) relative to the surface of the ellipse is determined by the angle φ of the slope of the right border of the beam relative to the horizontal axis connecting the foci of the ellipse.

Some beam from the beam has an angle φ + θ relative to the horizontal axis. The reflected beam corresponding to this beam has an angle φ '+ θ', where φ 'is the angle of inclination, relative to the horizontal axis, of the extreme reflected beam in the beam to the left, and θ' is counted from this beam. Since the angles ϕ are the same, the angle of incidence of the selected beam .

To determine the relationship between the angles θ and θ 'we use the equation of the ellipse in polar coordinates [1]

As can be seen from Figure 2, for each ray in the source beam, the relation ρcos (φ + θ) + ρ'cos (φ '+ θ') = 2ae holds. Then, substituting expression (1) into this relation, we find

cos (φ '+ θ') = F (φ + θ),

where, as follows from Figure 2,

cos (φ ') = F (φ + 2θ ₀ ).

Expression (2) establishes a relationship between θ and θ '.

For definiteness, suppose that the light guide element (and the ellipse in FIG. 2) are made of glass n ₁ ≡n = 1.55, around which there is air with n ₂ = 1. Source (12) creates a luminous flux within the angle 2θ ₀ = 30 °, with a Gaussian angular distribution of radiated power

dispersion Δθ = θ _0/5 = 3 °, (see Figure 3.)

The relative part of the radiation power of the source (12), released on Wednesday 2, is determined by the formula:

where the angle of incidence α = α (θ, φ) is determined by (0) taking into account expression (2). Reflection coefficient (in intensity) of unpolarized radiation

R (θ) = 1, θ> θ _* , θ _* is the angle of total internal reflection, ,

- known Fresnel reflection coefficients in field amplitude,

.

Figure 4 shows the fraction η (φ) of the radiation exiting out of the ellipse with the aspect ratio a / b = 2.

Plots with η (φ) = 0 correspond to total internal reflection. The slope angles φ ₁ = 73.2 ° and φ ₂ = 357.6 ° (corresponding to points 1 and 2 on the graph) are indicated at which η = 0.15 of the source power comes out. Points 4 and 3 correspond to angles 2π- (φ ₁ + 2θ ₀ ) = 256.8 ° and 4π- (φ ₂ + 2θ ₀ ) = 332.4 ° for beams symmetrical to beams with φ _1,2 relative to the horizontal axis. The surface areas of the ellipsoid through which 0.15 of the source power passes are indicated in FIG. 5.

It should be noted that a relatively small change in the angles leads to a noticeable change in the energy exiting the ellipse. For example, if φ _{1 is} reduced to φ ₁ = 71.8 °, i.e. by 1.4 °, it turns out that η = 0.1, and if φ _{1 is} increased to φ ₁ = 74.2 °, i.e. by 1 °, then η = 0.2. This is due to the fact that the reflection coefficient (5) substantially depends on the angle of incidence θ only for angles close to θ _* . Thus, with a strict requirement for a given power (with an error of less than 5%) of the output radiation, the surface shape of the light guide elements (as well as the position of the light source and the angular distribution of its power) must be maintained and known quite accurately.

The light guide member of FIG. 6 includes a source 1 and a portion A ₁ B _{1 of the} working surface with the orientation shown relative to each other. After reflection from section A ₁ B ₁ , with a partial exit to the outside, the beam will focus and will propagate towards the focus 2 of the ellipse. In order to redefocus the beam and direct it along the light guide element, the part of its surface from which the second reflection of the beam will occur should be a defocusing (i.e., concave relative to the direction of propagation of the beam) elliptical lens. At the same time, the angles of incidence of the beam on the surface of this lens should be greater than the angle of total internal reflection, then the radiation will not go out of the light guide element. Obviously, the second surface in the form of an ellipse with the same eccentricity e as for the first surface is not suitable, because the angles of incidence of the rays on it will be the same as on the first, i.e. is smaller than the angle of total internal reflection, and part of the radiation will come out of the light guide element (i.e., inside the ellipse). Thus, it is necessary either to change (increase) the aspect ratio for the ellipse corresponding to the second surface, or to rotate this ellipse relative to its focus so that when rays fall on its surface they all experience complete internal reflection. Obviously, if we take as part of the second surface a part of the ellipse with the length of the major semi-axis 3.3 and aspect ratio 2.2, as Fig.6 (the aspect ratio for the larger ellipse in Figure 6 is 2, and the length of its major axis is 4) , then each beam from the beam will experience complete internal reflection on this surface, and the light will not come out. Indeed, we determine, as can be seen from Fig.6, the angles φ ₁ 'and φ ₁ ”, according to (2) and

The angle of incidence of the beam on the area A ₂ B _{2 of the} surface is the same, for a beam falling on the area outside or inside the smaller ellipse in Fig.6 is determined by an expression similar to (0), where φ varies from φ ₁ 'to φ ₁ ”. The dependence α ₂ (φ), φ ₁ '<φ <φ ₁ ”is shown in Fig.7. As can be seen from Fig. 7, α ₂ (φ)> θ _* i.e. the radiation does not exit the light guide element through the portion A ₂ B ₂ . We note that the minimal aspect ratio for which α ₂ (φ)> θ _* is 2.16. For the internal ellipse in FIG. 6, you can take the aspect ratio a / b> 2.16, you can also change the dimensions of the ellipse while maintaining the aspect ratio, which will help optimize the relative position of the surface areas.

In order for the third reflection of the beam from the boundaries of the light guide element, i.e. from section A ₃ B ₃ in FIG. 6, a predetermined part of the total radiation power of the source (for example, the same 15% as when reflecting from section A ₁ B ₁ ) would come out; the surface shape of section A ₃ B ₃ should be different from the shape surface area of a large ellipse. But even if, by coincidence, it turns out that about 15% of the total source power leaves the portion A ₃ B _{3 of a} larger ellipse, then after the third reflection, in this case, the beam path will become difficult to describe, because the beam reflected from A ₃ B ₃ originates from point 2 in FIG. 6, which is not the focus of a large ellipse. Thus, the shape of the surface area A ₃ B ₃ should be changed so that it corresponds to a certain ellipse with focus at point 2 (it is also the focus of a small ellipse in Fig.6). The geometric parameters of this third ellipse should provide the output of a given fraction (15%) of light power.

It should also be noted that the angular distribution of the source power during the transition from it to section A ₃ B ₃ changes, both due to the exit of part of the radiation through section A ₁ B ₁ , outward, and due to focusing and defocusing of the beam when reflected from the surfaces of the fiber item.

Find the distribution function after the first reflection. Before focus

where α (θ, φ ₁ ) is determined by (0) taking into account expression (2). After focusing, power in a small range of angles

where θ and θ 'are related by expression (2). From equation (7) follows the distribution function after the first reflection

Define θ (θ '). Since expression (2) is symmetric with respect to φ '+ θ' and φ + 0, i.e. cos (φ + 0) = F (φ '+ θ'), then

θ 'varies from 0 to φ ₁ ”-φ ₁ ', and φ ₁ ”, φ ₁ 'are determined from expression (5a). Fig. 8 shows the angular distribution functions: the initial for the source is curve 1, after the first reflection before focusing - curve 2, after the first reflection and focusing - curve 3, for comparison, curve 4 corresponding to focusing at 100% reflection is shown.

Similarly, the angular distribution function f ₂ (θ ') is determined after the second (total internal) reflection — it is shown in Fig. 8 by curve 5,

In the calculations should take the eccentricity of the small ellipse in Fig.6 . The angle θ 'varies from 0 to 2θ ₂ = φ ₂ ”-φ ₂ ' = 29.1 °, where φ ₂ ” = arccos [F (φ ₁ ')], φ ₂ ' = arccos [F (φ ₁ ”)], θ (θ ') = arccos [F (φ ₂ ”+ θ') - φ ₁ '. As can be seen from Fig.6, after the second reflection, there was a slight focusing of the beam, compared with the original beam. It can be verified that, at the selected boundary elements of the light guide element, the beam after the second reflection contains 85% of the energy of the initial beam:

To determine the next surface area of the light guide element, an equation similar to (4) should be solved

Where

and φ ₂ = φ ₂ '+ θ, φ ₃ = arccos [F (φ ₂ )]. As the variable in expression (2) for F, we choose the eccentricity e, and the length of the major axis of the third ellipse can be chosen so that the third part of the surface of the light guide element is geometrically mated with the first. Thus, it is required to solve equation (11) η (е) = 0.15 with respect to e, which is included in the expression for φ ₃ . The solution of the last equation gives e = e ₃ = 0.723, which determines the aspect ratio . For the third part of the surface of the light guide element, you can choose an ellipse with a length greater than half axis a = 3.911, less than half axis b = 2.7, and the left focus of the third ellipse coincides with the left focus of the second.

In a similar manner, subsequent elements of the surface of the light guide element can be completed (in various ways). Figure 9 shows, for example, a light guide element, surface sections of which are obtained by determining the eccentricities of the corresponding ellipses and / or by tilting the axes of the ellipses relative to the horizontal. Such a light guide element is designed so that in its cross section a multilateral tapering figure is formed, limited by broken lines having a bulge towards the exit of the light flux from the light guide element. The radiation source is located at the end (the widest part of the cross section) of the said light guide element.

9, the light guide member is made of seven side faces that form a convex ellipsoidal surface for outputting radiation from said radiation source, and seven side faces that form a concave ellipsoidal surface to reflect radiation from said radiation source, respectively. 15% of the total radiation power comes out through the surface areas marked on the convex part of the light guide element, and light reflections from the areas marked on the concave part of the light guide element occur without radiation coming out.

Figure 10 shows the initial and angular distribution functions of the radiation after each reflection.

All of the above considerations were made for the case of a flat cross section. The real light guide element can be made in different ways. For example, a light guide element having, in cross section, a tapering figure of FIGS. 1, 6 or 9, can be made in the form of a plate obtained by parallel transfer of this tapering figure in a direction perpendicular to the plane of this figure. At the end of such a light guide element, a plurality of directional light sources, for example, LEDs, are placed.

Another example of a light guide member is shown in FIG. 11. Such a light guide element is made in the form of a body of revolution obtained by rotating the tapering figure of FIGS. 1, 6 or 9 around an axis lying in the plane of this figure and outside this figure near its sharp end. At the end of the light guide element, a plurality of directional light sources, for example, LEDs, are also arranged.

It is also possible to perform the light guide element in such a way that in at least one of the longitudinal sections in which the light flux propagates in the light guide element, a multilateral tapering figure is formed, limited by broken lines having a bulge towards the exit of the light flux from the light guide element. Moreover, the light guide element can be made both in the form of a plate bent with kinks obtained by parallel transfer of the said multilateral tapering figure in a direction perpendicular to the plane of this figure, and in the form of a body of revolution obtained by rotating the said multilateral tapering figure around an axis lying in the plane of this figure and outside this figure near its sharp end.

The placement of LEDs or other directional light sources at the end of any light guide element according to the present utility model is advisable to be made evenly if it is necessary to obtain a full light flux with a uniformly distributed density. Then, the generated luminous flux, in the case of making the light guide element in the form of a curved plate, will be directed in one direction, and in the case of the light guide element in the form of a body of revolution, in all directions.

It is clear that in another embodiment of the light guide element, for example, in the form of a convex body, similar to that shown in Fig. 11, but not spherical, but ellipsoidal in cross section perpendicular to the vertical axis, the light flux can have different densities in different directions.

This utility model can be used in demonstration signs, indexes of various information, illuminated advertisements, lighting devices for medical applications and other lighting devices.

Thus, the present utility model ensures the achievement of the goal by converting light beams from sources into one or more outgoing light beams of a larger cross section, giving a more uniform brightness of the outgoing beams over a cross section with high efficiency in the input and output of light radiation and in given directions of the outgoing beams .

Claims (10)

1. A lighting device comprising a fiber guide element made of an elongated shape and having at least one longitudinal section of the base and two sides tapering from the base to the top, the base of each of said longitudinal sections being located at the end of the fiber guide element, and a directional light source located at the end of the light guide element for directing the light flux to this end, the angle between the direction of the light flux from the directional light source and directed the extension length of the light guide member is selected in such a range that the light flux experiences at least one total internal reflection from said tapering sides in said at least one longitudinal section of the light guide member and exits through one of these tapering sides after at least one of said total internal reflections. 2. The device according to claim 1, in which the refractive index of the material of the light guide member, as well as the limits of the angles between said tapering side sides in those of said longitudinal sections in which the light flux propagates, and said range of angles at which the light flux enters the light guide member is selected so that the light flux exits through the same of the tapering sides. 3. The device according to claim 2, in which the light guide element is made curved so that in at least one of the aforementioned longitudinal sections, in which the light flux propagates in the light guide element, a smoothly narrowing figure is formed with a bulge towards the exit of the light flux from the light guide element. 4. The device according to claim 3, in which the light guide element is made in the form of a smoothly curved plate obtained by parallel transfer of the aforementioned smoothly tapering figure in a direction perpendicular to the plane of this figure, and a plurality of directional light sources are placed at the end of the light guide element. 5. The device according to claim 3, in which the light guide element is made in the form of a body of revolution, obtained by rotating said smoothly tapering figure around an axis lying in the plane of this figure and outside this figure near its sharp end, and a plurality of directional light elements are placed at the end of the light guide element sources. 6. The device according to claim 2, in which the light guide element is made curved so that in at least one of the aforementioned longitudinal sections, in which the light flux propagates in the light guide element, a multilateral tapering figure is formed, limited by broken lines having a convexity towards the exit of the light flux from the light guide element. 7. The device according to claim 6, in which the light guide element is made in the form of a plate bent with kinks, obtained by parallel transfer of the said multilateral tapering figure in the direction perpendicular to the plane of this figure, and a plurality of directional light sources are placed at the end of the light guide element. 8. The device according to claim 6, in which the light guide element is made in the form of a body of revolution obtained by rotating said multilateral tapering figure around an axis lying in the plane of this figure and outside this figure near its sharp end, and a plurality of directional light elements are placed at the end of the light guide element sources. 9. The device according to any one of claims 1 to 8, in which the directional light sources are placed at the end of the light guide element evenly. 10. The device according to claim 9, in which the LED is used as at least one directional light source.