WO2009063520A1

WO2009063520A1 - Light-weight lighting bodies with led matrix

Info

Publication number: WO2009063520A1
Application number: PCT/IT2008/000672
Authority: WO
Inventors: Fabrizia Ianiro
Original assignee: Ianiro Aldo S.R.L.
Priority date: 2007-11-13
Filing date: 2008-10-30
Publication date: 2009-05-22
Also published as: ITRM20070588A1

Abstract

An optimization technique of the balancing of the color temperature parameters in a lighting body formed by the assembly of selected LEDs, wherein a suitable mixing of colors is carried out for producing chromatically calibrated light on sensitive materials, along with the micro-programmed regulation of the power supply so to continuously vary, over the widest band of possible values, the emission and the separate calibration of the Red/ Amber color percentage in order to obtain the desired chromatic balancing.

Description

Light-weight lighting bodies with led matrix

Pertaining sector of the invention

The invention generally makes reference to lighting bodies with light emitting diode matrix (from hereon also referred to as only LED) having as subject the lighting devices which employ the light supplied by multiple LEDs assembled on a single lighting body.

More in particular, this is a new lighting unit which comprises a series of light diodes arranged in a single housing and is capable of producing the light of a particular color, through the simultaneous activations of different light emitters, regulated by means of each related control device so that the intensities of the corresponding color emissions from each of the diodes are combined in order to supply the emission color desired by a part of the lighting body.

State of the art

Light emitting diodes are well known solid state light sources. They are widely used in many technical sectors for their low energy consumption and for their long duration. Limited by technical problems, the first LEDs were only capable of generating monochromatic light. The current LEDs are capable of generating several primary colors. In addition, LEDs have numerous advantages with respect to the traditional light sources, such as incandescent bulbs or fluorescent bulbs, since they are more economical to produce and also require less activation energy. In particular, they are preferred since they emit light with a high efficiency over specific colors of the spectrum. Nevertheless, such components do not form per se focused light sources, and for this reason suffer from relatively low output luminosity. The lack of focusing and the reduced luminosity would lead to not using LED lighting systems where a high lighting intensity is required. In addition, the light provided by a LED could not be intensified without the use of an optical device set for concentrating the beam. There are, on the other hand, numerous commercial applications which require the source device to have a high luminosity with specific chromaticity of the light beam; for example, there is a considerable request for such type of lighting in the photo-film-television and stage sector. In particular, if the lighting body is formed by an assembly of LEDs with specific colors, it is necessary to avoid problems related to color variations depending on the characteristics of the LEDs themselves, and it is appropriate to select and use the LEDs such that the light intensity and the emission wavelength of the light of the single LED falls within a certain range/field of values. With regard to such variations, two factor types are defined: a) luminosity and intensity variations (luminance), b) variations of the light emission wavelength (chromaticity). The fundamental differences in the emission intensity and color of single LEDs, even if having the same nominal color, derive from the manufacturing processes. Such differences can supply significant non-uniformities in the Color Rendering when the LED matrices are used in assembled multi-LED modules.

The COLOR RENDERING INDEX (CRI) is a parameter indicative of the magnitude of the light reflected by a color sample subjected to a particular light source, compared with the light reflected by the same sample in the presence of a light source normalized at 3200°K. The CRI is thus used to indicate how much a light source is capable of rendering the color of the objects which are agreeably appreciable in vision. Such comparison is carried out with the aid of a predetermined eight color scale test, under sample light and in comparison with the light to be examined at 3200°K; in such case, the CRI can reach the value 100.

In some commercial or residential type applications, very high Color Rendering is desired, though in any case relative to comparison with tungsten sources at 3200⁰K. Although the lighting systems according to the standards have optimized functional characteristics, including supplying uniform and diffused lighting, a high efficiency, and a low level of developed heat, they often do not fully satisfy the needs of such applications. More recently on the LED market, two production trends have been observed:

• the first area of monochromatic LEDs with saturated and intense coloring, but with emission characteristics adapted only for generic use or for displaying electrical functions on panels or for generic portable lighting use in home and industrial settings.

• the second area of latest-generation chromatically-corrected and selected LEDs belonging to groups whose light emission can be established with precision and constancy in the color temperature zone in the line identified inside the CIE coordinates (CIE = Commission International de l'Eclairage). But the assembly of generic LEDs (with non-selected production) cannot produce bodies for photo-film-television stage lighting, since such LEDs have marked coloring that cannot be traced to color temperature parameters. The object of the present invention is that of providing a lighting body, constituted by the assembly of selected commercial LEDs, which has an optimal balancing of the color temperature parameters.

A further object of the present invention is that of obtaining a consistent Color Rendition through the combination of a set of LEDs arranged in assembly matrices, reducing both the intensity variations and the color variations with regard to the non-homogeneity deriving from the LED production process. Still another object of the present invention is to provide a new lighting device with a combination of LEDs in a single housing or unit, capable of emitting a variety of colors and/or tones as a function of the energy which is supplied to the emitters supported in each housing.

Another object of the present invention is to provide the carrier structures for matrices of lighting emitting diodes which incorporate, in addition to the light emitting devices, the circuit means for adjusting the color intensity variations at the anode of each light emitter, in a separate manner, so that any light tone can be emitted by the single lighting device, in particular the tone relative to white. Finally, an object of the present invention is that of supplying a light-weight lighting body with LED matrix, which employs electrical and electronic components, hardware, base software, standard technical lighting assembly containers, in order to make the system itself with limited costs, high reliability and easy maintenance.

These and other objects which will be clear during the description are obtained by means of the light-weight lighting bodies with LED matrix according to the attached claims.

Brief description of the drawings

The invention will be better comprehended from the reading of the following description, given as merely an example and made by making reference to the drawings, wherein:

FIGURE 1 is a typical chromicity diagram;

FIGURES 2 A, B, C, D, E are views of a first configuration of the lighting bodies according to the present invention;

FIGURES 3 A, B, C are views of a second configuration of the lighting bodies according to the present invention; FIGURES 4 A, B, C, D are views of a second configuration of the lighting bodies according to the present invention;

FIGURES 5 A, B, C, D are section views which highlight the expedients introduced for the heat dispersion.

Preferred embodiments of the invention

Color perception theory is currently specifically defined as described in the reported supplied by the Commission International de l'Eclairage (CIE). It is based on a chromaticity diagram of the type in FIG. 1, by means of which the resulting color is defined based on an additive combination of pure, or even impure spectral colors.

The table of the corresponding letters is the following, according to international law:

Color measurement is usually carried out with a thermocolorimeter, a photoelectric instrument which allows carrying out measurements on the light sources and on the surfaces on which the light is reflected according to the trichromatic system CIE. The radiation by a normal LED is "impure", since the light which is emitted is distributed over a band of wavelength values. The distribution of the wavelengths (or spectrum) is moreover variable from one LED to another, even when the LEDs come from the same manufacturing process. A lighting body can be made by using three LEDs whose colors are the nominal primary colors red, blue and green. With regard to the chromaticity diagram, a module thus formed could represent a band of chromatic values defined by a triangle whose vertices are the current colors of its component LEDs. It will instead be observed how the combined color that is desired and obtainable from the lighting body according to the present invention is obtained by means of the combination of only two colors, white and red/amber LEDs, present according to predefined and variable percentages in relation to the particular tone which one wishes to achieve in the emitted light beam.

In addition, the color control, in the scope of the obtainable value ranges, is carried out by means of regulation of the electric current which polarizes the anode of each LED comprised in the module. The band of available colors varies from one module to another due to the different spectra emitted by the LEDs. With regard to the CRJ of bodies not corresponding to 3200K, the CIE (Commission International de l'Eclairage) with a recent recommendation of February 2007 stated that the method introduced in 1974 and described in the publication CIE 13.3-1995 contradicts the visual response in situations of lights that contain white LED.

In light of this contradiction, a new type of evaluation tests applicable to LEDs has been formulated.

In the current case, the CRI index, having been declared unsuitable for measuring the color rendering, is only taken under consideration as information presented by leading sector manufacturers, such as LUMILEDS™, in order to have a classification corresponding to the old CIE dictates. Except if the emission of the LEDs is in any manner compromised by the assembly in the constructed lighting bodies, it has been deemed appropriate to adapt the emission to the specific sector of interest (photo-film-television shooting) by resorting not so much to the CRI index, moreover already stated by the LED manufacturing company, but by making uniform and correlating the light response to the traditional chromatic measurement of the color temperature, deemed more suitable in practical use with the indicated materials.

The "mixture" used, therefore, produces balancing suitable for the Red - Blue correction at a color temperature of 5500° K, a chromatic correction for the remaining excess Blue and a compensation for the Green - Magenta ratio for obtaining a measure deviation not greater than 5 CC degrees (according to the unified graduated scales of Kodak™ or other producers).

The LEDs selected among the LUMILEDS products were chosen in the YO and XO areas, adding Red - Amber LEDs in a percentage ranging from 16% to 14%, in the area of 617 - 625 nanometers. In addition, the illuminators according to the finding are light-weight bodies with compact and simple structure formed by sets of 54 LEDs, Fig. 2, on three concentric layers of 18 LEDs each, or of 6 LEDs, Fig. 4, on two lines of 3 or 7 LEDs with circular form, Fig. 5.

Based on a specific embodiment, a lighting body is provided as reported in Figures 2 and 3, composed of a module comprising a series of light emitting diodes, the LEDs being installed on a power supply carrier plate, dissipator of the heat generated during emission.

Such module comprises a dielectric structure, and a plurality of electrical conductive contacts arranged on the dielectric element. The contacts are configured in order to mount a series of LEDs for supplying current to the LEDs themselves. The assembly also comprises a conductive element of the heat produced and a box of electrical connections. Contributing to the compactness of the bodies is the structure with cell-like support plates, arranged as a radiator for facilitating the dispersion of the residue heat.

Such plates have the object of holding, in correct position, the flow concentrator and collimator lenses designed to bring the emission from a 110° angle of the base LEDs to the angle desired according to the type of illuminator. Lateral supports hold all parts of the apparatus, allowing the modular combination of several apparatuses with suitable threads.

Accessories suitable for modifying and filtering the light emission are held with particular tongues and magnets. Based on a preferred embodiment of the present invention, the lights related to the primary colors are mixed in a reflecting recess of a base of the LEDs in order to form the light beam of a specific color, which is emitted through the housing structure of the LED matrix. It is preferable that the peripheral walls and the bottom surface of the reflecting recess are covered with a cuttering agent layer in order to provide an effective light mixing. In the base zone of the carrier structure, a series of PINs are situated, spaced in an equidistant manner with respect to each other for the connection of the microchips, and with the other end penetrating inside the base. According to such arrangement, without increasing the volume of the LED assembly, the number of the PINs and chips is increased so as to optimally control the color of the light which must be emitted.

A fundamental and distinctive element of the described solution is the presence of a microchip which controls: i- the possibility to reduce the power supply, in order to continuously vary the emission from 0% to 100%, ii- the separate calibration of the Red/ Amber color percentage in order to obtain creative chromatic balancing, obtaining warm or cold tints.

This is made possible through the following characteristic operating steps: Point 1. turning on via pressing the on-off button, with restoration of the preceding setting.

Point 2. overall regulation of the light emission through an up-down button, with display in ten progressive steps.

Point 3. manual regulation by activating the red button of the light level relative to the red LED of the LED mixture of the lighting body. At the same time, there is the insertion of the manual control of the white by means of the second function of the up-down buttons.

Point 4. display of the low battery level with flashing red LED.

Point 5. turning off function, via pressing the on-off button. The previously set values are reactivated at the subsequent starting.

Point 6. upon reaching a voltage value less than 7 V, the electronics turns off the lighting body.

Point 7. the electronics is protected from polarity reversals.

Claims

1. An optimization technique of the balancing of the color temperature parameters in a lighting body formed by the assembly of generic LEDs characterized in that it arranges a mixture of colors suitable for producing chromatically calibrated light on sensitive materials and the micro-programmed regulation of the power supply in order to continuously vary, over the widest band of possible values, the emission and the separate calibration of the Red/ Amber color percentage so to obtain the desired chromatic balancing.

2. An optimization technique of the balancing of the color temperature parameters in a lighting body formed by the assembly of selected LEDs according to claim 1, characterized in that it adapts the emission of the LEDs to the specific sector of interest, not resorting to the CRI index, stated by the LED manufacturing company, but making uniform and correlating the light response to the chromatic measurement of the color temperature.

3. An optimization technique of the balancing of the color temperature parameters in a lighting body formed by the assembly of generic LEDs according to the preceding claims, characterized in that it carries out the Red-Blue correction at a color temperature of 5500° K, a chromatic correction for the remaining excess Blue and a compensation for the Green-Magenta ratio in order to obtain a deviation of not greater than 5 CC (COLOR COMPENSING) degrees, according to the unified graduated scales.

4. An optimization technique of the balancing of the color temperature parameters in a lighting body formed by the assembly of LEDs according to the preceding claims, characterized in that it selects the LEDs from among the chromatically corrected selected products based in the YO and XO areas, adding Red - Amber LED in a percentage ranging from 16% - 14%, in the area of 617 - 625 nanometers.

5. An optimization technique of the balancing of the color temperature parameters in a lighting body formed by the assembly of selected LEDs according to the preceding claims, characterized in that it comprises the following operating steps: i- activation with initial setting which restores the previous setting, ii- overall regulation of the light emission through micro-programmed control with N progressive steps, and displayed for real time tuning, iii- manual regulation with activation of the light level control relative to the red LED in the LED mixture of the lighting body; at the same time, there is the insertion of the manual control of the white by means of a second dedicated regulation function.

6. An optimization technique of the balancing of the color temperature parameters in a lighting body formed by the assembly of generic LEDs according to the preceding claims, characterized in that the turning off function detects the magnitude of the chromaticity correction carried out, providing for the storage of the related chromaticity correction coefficients, the previously set values being reactivated at the subsequent starting.

7. A lighting body formed by the generic LEDs assembly with compact structure, in which the LEDs are installed on a power supply carrier plate, dissipator of the heat generated during the emission, characterized in that it comprises an apparatus with carrier structures arranged so to distribute the LEDs in an equidistant manner, and cell-like support plates arranged as a radiator for facilitating the residual heat dispersion, such plates holding in correct position flow concentrator and collimator lenses that are adapted to bring the emission from a 110° angle of the base LEDs to the angle desired according to the type of illuminator.

8. A lighting body formed by the generic LED assembly with compact structure according to claim 7 and characterized in that it comprises lateral supports set to hold all the parts constituting the lighting body, allowing, with threads, the modular combination of several devices.