WO2015140789A1

WO2015140789A1 - Lighting system configurations and methods of manufacturing and operating them

Info

Publication number: WO2015140789A1
Application number: PCT/IL2015/050274
Authority: WO
Inventors: Vasilii TIKHONOV; Alexander NIKOLSKIY
Original assignee: Firefly Smart Engineering Ltd.
Priority date: 2014-03-18
Filing date: 2015-03-16
Publication date: 2015-09-24
Also published as: IL231562A0; IL231562A

Abstract

A lighting system comprising a driving circuitry connectable to a lighting apparatus, where the driving circuitry comprises a constant current source for powering the lighting apparatus and a stabilizing circuitry electrically coupled to the constant current source for adjusting the voltage over the constant current source. The stabilizing circuitry may comprise at least one capacitive element and a controlled current source operable for controllably charging the at least one capacitive element so as to maintain a substantially constant electrical power supply of the lighting apparatus.

Description

LIGHTING SYSTEM CONFIGURATIONS AND METHODS OF MANUFACTURING AND OPERATING THEM

TECHNOLOGICAL FIELD

The present application is in the field of lighting systems, and in particular, lighting systems employing light emitting diodes.

BACKGROUND

The use of light emitting diodes (LEDs) technology for common lighting purposes is rapidly increasing. LED lighting utilizes solid state semiconductor (e.g. , aluminum-gallium-arsenide) lighting elements for generating light from excited electrons. LED lighting is significantly more compact and efficient than conventional incandescent bulbs (e.g. , about 85% more efficient), and more efficient than fluorescent bulbs (e.g. , about 10% more efficient). In addition, LED lighting elements are typically more durable and less prone to breakage, than standard filament and fluorescent based lighting elements. Typical LED lighting elements are made of several small LEDs enclosed inside a bulb or a tube, that produces bright light and that consumes less energy than fluorescent based lighting elements.

LED tubes are designed to replace traditional florescent mercury vapor based lighting elements. The life rate of an LED light tube is generally about 50,000 hours, it does not flicker, typically requires replacing only once every 10 years or more, and can use existing fluorescent light fixtures.

Some types of LED light tube implementations known from the patent literature are described below.

US Patent No. 7,553,051 describes a LEDs work light designed to provide a desired radiation pattern using optical components designed to produce a beam, which may be changed by refractive -reflective optics or by convex lenses, and which may be operated by a ballast fed from line voltage AC or low DC voltage.

US Patent No. 7, 132,785 describes an illumination system including a first LED and a carrier material, and which may also contain material for converting electromagnetic radiation into illumination or visible light.

US Patent Publication No. 2011/299276 describes a LED light tube including a tube, a LED light module, two end caps and a starter hidden in one of the two end caps, wherein the tube includes a board and a transparent cover which is mounted to the board. The LED light module is connected to the board by fixing a circuit board thereof to the board. The board further includes heat dispensing fins to quickly release the heat from the LEDs on the circuit board, and two reflection plates connected to the board for increasing illumination of the light tube.

US Patent Publication No. 2009/290334 describes a LED-based replacement light for a fluorescent socket constructed such that an entirety of a radially outer portion of a tubular housing at least partially defined by a high-dielectric light transmitting portion is formed of a high-dielectric material, to thereby prevent a person handling the light from being shocked as a result of capacitive coupling occurring when the LED- based replacement light is installed one end at a time. A circuit board is in thermally conductive relation with the tubular housing, allowing for conduction of heat generated by the LEDs from a side of circuit board opposite the LEDs to the tubular housing for dissipation to the ambient environment.

German Patent Publication No. DE 10255247 describes a light element comprising a number of light-emitting diodes on at least one plate with appropriate connections, with a surrounding tube made of mineral glass.

Another possible LED lighting arrangement is a flat two-dimensional array of LEDs, which are typically mounted on a single printed circuit board (PCB). US Patent No. 7,191,515 describes an electrical assembly formed from two interconnected circuit boards where conductive spacers and a conductive material are placed between complementary bond pads on the circuit boards. The conductive spacers are formed from a material that maintains its mechanical integrity during the process of attaching the circuit boards. The conductive material is a solder or conductive adhesive used to mechanically attach the circuit boards. An insulating material is inserted into an interface region between the circuit boards. The insulating material provides additional mechanical connection between the circuit boards. In one embodiment, one circuit board includes a glass panel that holds an array of organic light emitting diodes (OLEDs), and the other circuit board is a ceramic circuit board. GENERAL DESCRIPTION

There is a need in the art for efficient cost-effective lighting devices that operate with direct currents (DC) and/or voltages (e.g. , using LEDs), that can be easily and quickly assembled, and that can provide good power factors and luminosity. Designs of DC voltage lighting devices typically tackle efficient heat sinking requirements, design of complex frequency controlled driving circuitries for providing ripple free power supply from the AC electric network, and the addition of optical elements for beam shaping and directing to obtain desired illumination patterns.

The inventors of the present invention have developed novel lighting structures and configurations which, in some embodiments, can be used to easily and efficiently assemble elongated lighting structures that are mountable inside transparent/translucent tubes or in transparent/translucent horizontally truncated cylindrical structures. In some possible embodiments planar lighting grid structures are provided that can be easily and quickly constructed from a plurality of lighting board strips in a modular fashion. A novel driving circuitry for the lighting structures is also described herein, which simplifies the electric design considerations and that can be conveniently embedded on circuit boards on which the light emitting elements of the lighting structures are mounted. Methods for efficient operation of the lighting structures were also developed to provide simplified and accurate ambient light intensity measurements and improve control over the intensity of light produced by the light emitting elements based on the measured ambient light intensity.

One inventive aspect of the subject matter disclosed herein relates to a lighting apparatus configured in the form of a horizontally truncated cylinder. The lighting apparatus comprises an elongated circuit board electrically connectable to an electric power source and carrying an array of light emitting elements electrically connected thereon and operable for activation by the electric power source, an elongated transparent, or semi-transparent, cover having a rounded cross-sectional shape, and elongated attachment elements connecting lateral sides of the elongated circuit board to lateral sides of the cover. The circuit board may comprise electrical circuitry adapted for powering the light emitting elements.

A yet another inventive aspect of the subject matter disclosed herein relates to techniques and configurations for encapsulating a circuit board strip, comprising a plurality of light emitting elements (e.g. , LEDs) and, optionally, electrical circuitry for powering the light emitting elements, inside a transparent or semi-transparent tube. The encapsulation technique is designed to provide an efficient heat sink structure designed to also implement internal light reflecting surfaces. In some embodiments the encapsulation of the circuit board strip inside the tube is performed using an elongated support structure having a generally "C" cross-sectional shape configured to form two elongated elastic support elements, and an elongated light reflecting recess located between and extending along the support elements. The board strip may be attached to an external surface (base section) of the elongated support structure in its elongated recess, or, in some embodiments, preferably, the board strip is used as a connecting means to which the elongated support elements are attached at lateral sides thereof.

The elongated support structure and the circuit board strip mounted in its elongated recess and/or base section may be configured in the form of a depressible lighting "insert" that can be easily inserted and mounted inside a tube by pressing the elastic support elements one towards the other and pushing the elongated profile into the tube. After placing the lighting insert inside the tube, the pressed support elements are released inside the tube such that they become pressed against the internal surfaces of the tube.

The elongated support structure, having the circuit board strip mounted on its recess or base section, may be made of a heat conducting material to efficiently distribute heat from the circuit board strip along the support elements pressed against the inner walls of the tube, and from the support elements to the walls of the tube and to the environment. The support elements may be substantially circular (arc shape) in cross-section. In some embodiments the support elements cover about 20 to 60 % of the internal surface of the tube. In this way the circuit board strip can be efficiently sealed inside a closed tube while providing good internal heat distribution and desired illumination patterns.

Advantageously, the material from which the elongated support structure is made is also optically reflective and elastic (e.g. , aluminum). Alternatively, one or more light reflecting layers may be applied over the elongated recess to provide the needed light reflecting properties. In possible embodiments the support elements may comprise elastic materials and/or elements (e.g. , metal leaf/torsion springs).

In some possible embodiments the support elements may be configured to position the circuit board strip at a certain distance from the wall of the tube to optimize illumination therefrom and obtain a desired beam angle and illumination coverage from the tube. The reflecting surfaces may be configured to define a beam angle of about 10° to 120°. In this way, illumination from the tube may be configured to provide illumination in predefined beam/field angles, and thereby improve illumination efficiency and luminosity.

Another inventive aspect of the subject matter disclosed herein relates to a lighting panel configured for carrying an array of light emitting elements designed to significantly reduce the costs (as well as weight) of the panel, while facilitating adjustment, and arrangement, of a number of light emitting elements to objects/indicia to be illuminated. In possible embodiments multiple light emitting elements sites are arranged within a grid-like support structure carried by, or integral with, a frame (or board), rather than the continuous-surface or bulk structure of the panel. The light emitting element sites are defined by circuit board strip configurations allowing establishing mechanical and electrical connection to a power supplying frame or board, using soldering material compositions deposited at one or two end regions of the circuit board strips. The power supplying frame/board is configured to include a plurality of ports each configured to receive an end section of a circuit board strip, and a soldering material composition deposited thereon. The ports further include soldering bays comprising a soldering material composition used to establish electrical connection between the power supplying frame/board and the circuit board strips.

In some embodiments connection between the power supplying frame/board and the circuit board strips is established by aligning the soldering material composition at the end region of each circuit board strip with one of the soldering bays of the power supplying frame/board and heating the soldering material compositions (e.g. , using infrared radiation and/or hot air) in the soldering bays and on the circuit board strips to a melting temperature thereof, and allowing the melted soldering material compositions to combine and solidify, thereby establishing the needed electrical and mechanical connectivity. This configuration provides modularity in the construction of the lighting structures, flexibility in their design, reduction in printed circuit surface area and width, and permits use of an automated manufacture process of such lighting structures.

In some embodiments, light dispersing optical elements are provided on top of at least some of the light emitting elements of the circuit board strips to provide wider angles of illumination from the circuit board strips.

A yet another inventive aspect of the subject matter disclosed herein relates to a driving circuitry operable to receive an alternating electrical power supply and produce a substantially stabilized direct electrical current for powering a direct current consumer device/load (e.g. , lighting apparatus). The driving circuitry is configured to provide high power efficiency and high power factor, and permits operation with service power supply (main) frequency (e.g. , 50 Hz) without requiring high frequency regulation/conversion circuitries. In the driving circuitry, a constant current source is used for providing the direct current supply for powering the load (e.g. , light emitting elements such as LEDs), and a stabilizing circuitry electrically coupled to the constant current source is used to control the voltage over the constant current source. The stabilizing circuitry may comprise a controlled current source (e.g. , voltage controlled current source) and at least one capacitive element, and it is adapted to regulate charging current of the at least one capacitive element and thereby adjust/stabilize the voltage over a parallel branch (also referred to as load branch) comprising the load and the constant current source feeding the load.

Optionally, and in some embodiments preferably, a filtering circuitry is used to substantially attenuate one or more harmonics of the frequency of the electric (e.g. , grid) power, that are induced by the load and/or its driving circuitry, and thereby significantly improve the power factor of the device.

A rectifier (e.g. , a diode bridge) may be used to rectify the electric supply provided to the driving circuitry. A feedback branch/circuitry coupling between the constant current source and the stabilizing circuitry (the controlled current source) may be used to provide feedback signals to the controlled current source for regulating the charging currents supplied to the at least one capacitive element by the controlled current source. In some embodiments the feedback circuitry is configured and operable to provide the stabilizing circuitry control signals, being substantially proportional, to an electrical voltage over the constant current source. In some applications the feedback circuitry comprises a capacitor connecting between the at least one capacitive element and the stabilizing circuitry (the controlled current source).

In some embodiments a control unit is used to adjust control signals of the controlled current source according to voltage changes across the constant current source and adjust the charging of the at least one capacitive element accordingly. For example, and without being limiting, the feedback branch may comprise a control unit configured and operable to sample/measure the voltage over the constant current source and adjust the feedback signals provided to the controlled current source to adjust the charging current supplied to the capacitive element accordingly, and thereby maintain the voltage over the constant current source at a desired operating level.

For example, and without being liming, the control unit may be configured and operable to adjust the feedback signals provided to the controlled current source so as to decrease the charging current supplied to the capacitive element whenever the voltage measured over the constant current source is greater than some predefined high threshold level, and to increase the charging current supplied to the capacitive element whenever the voltage measured over the constant current source is smaller than some predefined low threshold level. The feedback branch may comprise a capacitor coupling between the controlled current source and the capacitive element.

The control unit may be also configured and operable to sample the voltage level of the mains directly, in addition to the sampling of the voltage over the constant current source, and adjust the control signals accordingly for regulating the charge current of the capacitive element. It is however noted that sampling/measuring of the voltage over the constant current source should be sufficient for properly adjusting the control/feedback signals provided to the controlled current source.

The driving circuitry may comprise a compensation circuitry/branch coupling between the controlled current source and the load, and operable to adjust the charging current supplied by the controlled current source in response to fluctuations in the power supply provided to the driving circuit. For example, and without being limiting, the stabilizing circuitry may comprise a resistor connected in series to a capacitive circuitry comprising a capacitor and a Zener diode connected in parallel to each other. A diode may be used to couple between the controlled current source and the capacitor of the feedback branch such that the cathode terminal of the diode is connected to the controlled current source and to the stabilizing circuitry, to thereby prevent discharge of the capacitor of the compensation circuitry.

The driving circuitry may be configured to provide power efficiencies in the range of 0.8 to 0.85, power factors in the range of 0.85 to 0.9, and it is suitable for use with high efficiency LEDs (e.g. , 180 lm/w), while maintaining very small ripples in the driving current supplied to the LEDs.

An additional inventive aspect of the subject matter disclosed herein relates to an ambient light intensity measurement technique usable for controlled activation of a lighting device, which does not require special arrangements of the light sensing assembly and is configured to prevent measurement interferences due to light emitted from the lighting device. In order to measure the intensity of the ambient light, the operation of the lighting device (its illumination) is stopped/deactivate for a duration of time adequate for measuring the ambient light intensity (about 1 millisecond), and thereafter it is activated back (ON) to its illuminating state. In order to prevent illumination changes in the light produced by the lighting device, that may be detectable by human eyes, a series of consecutive illumination stoppages/deactivations are performed before carrying out any measurements e.g., with substantially the same time gaps between consecutive stoppages/deactivations, starting from minimal illumination stoppage time, where the time periods in which the illumination is stopped is gradually/progressively increased until the adequate time duration for intensity measurement is reached. The intensity of the ambient light is measured during the adequate time duration stoppage, and a series of illumination stoppages/deactivations is thereafter performed with substantially the same time gaps between consecutive stoppages, where the time periods in which the illumination is stopped is gradually/progressively decreased until reaching the minimal illumination stoppage time. The gradual increase in the illumination stoppage time, followed by the gradual decrease of the illumination stoppage time, conceals the illumination stoppage required for measuring ambient light intensity and makes it undetectable to human eyes, and thus provides that illumination appears to be continuous.

Accordingly, in another aspect there is provided a method of measuring ambient light intensity in a vicinity of a light source. The method comprises generating a sequence of light illumination stoppages of the light source, starting from a minimal illumination stoppage time, and gradually increasing illumination stoppage time of each consecutive illumination stoppage within the sequence until reaching an adequate stoppage time duration, measuring the ambient light intensity during at least the adequate stoppage time duration, and thereafter, generating another sequence of illumination stoppages of the light source with gradually decreasing illumination stoppage time of each consecutive illumination stoppage within this (other) sequence until substantially reaching the minimal illumination stoppage time.

A light detector may be used by the control unit to determine intensity of ambient light in a vicinity of the lighting apparatus according to measurement data produced by the light detector, and to regulate the current supplied by the driving circuitry to the lighting apparatus accordingly. The control unit may be configured to use the ambient light intensity measurement technique described hereinabove and hereinbelow for measure ambient light intensity by the light detector.

In some embodiments the lighting apparatus comprises an elongated circuit board having electrical conductors electrically connectable to an electric power source (e.g. , the driving circuitry described hereinabove and hereinbelow), an array of light emitting elements mounted on the circuit board and electrically connected to the electrical conductors, an elongated transparent, or semi-transparent, cover having a rounded cross-sectional shape defining inner and external surfaces of said cover, said inner surface comprising gripping sections each extending along and adjacent a lateral side of the cover and connecting a lateral side of the circuit board to the cover, said external surface comprising fastening sections each extending along a lateral side of the cover and adjacent to one of the gripping sections, and elongated attachment elements, each connected to one of the fastening sections of the cover and being adapted to fasten the connection established between the adjacent gripping section and the lateral side of the circuit board.

At least one of the gripping sections may comprise an elongated channel operable to receive and hold a lateral side of the circuit board. At least one of the fastening sections may comprise an elongated channel and at least one of the attachment elements may comprise a respective elongated rail section configured to tightly fit inside the elongated channel. At least one of the attachment elements may comprise a support member protruding from the rail section and extending therealong and the fastening section may comprise a respective elongated groove adapted to receive the support member. At least one of the attachment elements may comprise a support member protruding from the rail section and extending therealong, the support member being adapted to be received in a respective internal channel formed inside, and extending along the elongated channel of the at least one of the fastening sections.

In some embodiments the lighting apparatus comprises a transparent or semi- transparent tube and an insert assembly (e.g. , a depressible insert) positioned inside the tube. The insert assembly comprises an elongated circuit board having electrical conductors connectable to an electric power source (e.g. , the driving circuitry), an array of light emitting elements mounted on the circuit board and electrically connected to its electrical conductors, an elongated support structure having an elongated recess or base section extending along an external surface thereof for receiving and mounting the elongated circuit board therein, and support elements at lateral sides of the elongated recess or base section, the support elements configured to engage internal surfaces of the tube and enable fitting the elongated support structure inside the tube.

Optionally, the tube of the lighting apparatus may comprise two or more areas having different levels of transparency configured to provide a certain illumination pattern/profile of the light passing therethrough.

The elongated support structure may comprise an elongated reflector surface having a curved sectional shape and mounted therein facing the circuit board. This asymmetric reflector configuration may be adapted to reflect a relatively narrow beam of light emitted from the light emitting elements towards the wall of the tube.

In some applications the elongated support structure is made of two separate elongated members, each comprising a respective one of the support elements and an attachment section configured to connect to a lateral side of the elongated circuit board. Optionally, the attachment sections of the elongated members are configured to form the elongated recess together with the circuit board being connected to them. For example, and without being limiting, each support element may be connected to a respective attachment section, or to the base section carrying the circuit board, via a slanted (or curved) section of the support member, and the slanted (or curved) sections may be configured to reflect the light from the light emitting elements towards the wall of the tube. Optionally, at least one of the slanted sections of the support element is curved or of parabolic shape, thereby forming an asymmetric reflector structure capable of providing a required illumination distribution/profile over a plane being lit.

In some applications the support elements are configured to position the elongated recess and the circuit board mounted in it at a predetermined distance from the wall of the tube. Optionally, the support elements are depressible elements operable for snugly fitting the elongated support structure inside the tube. In a variant, the elongated recess is adapted to reflect light emitted by the light emitting elements. In another variant the elongated support structure may comprise a heat conducting material serving as a heat sink.

The lighting apparatus may comprise lids adapted to attach over and close openings formed at the extremities of the lighting apparatus. Optionally, each lid comprises a support section for holding/elevating an end extremity section of the circuit board and thereby forms a gap between the circuit board and a surface on which said lighting apparatus is to be mounted.

In some possible embodiments the lighting system comprises a plurality of elongated panels each carrying an array of light emitting elements and one or more patterns of a soldering composition material deposited on the panel, the soldering material composition patterns being electrically connected to the light emitting elements, a frame connectable to an electrical power source (e.g. , the driving circuitry described herein) and comprising a plurality of pass through holes, each one of the pass through holes configured to provide electrical connection to the power source and fit and mate with one of the soldering material patterns deposited on one of the panels, each one of the holes being configured to receive soldering material composition inside it and establish mechanical and electrical connection with one of said panels by combining the received soldering material composition with the soldering material pattern provided on the panel.

The holes and the soldering material composition patterns may be configured to align the panels carrying the patterns with respect to the frame. Optionally, light dispersing elements are optically coupled to at least some of the light emitting elements. In a variant, the elongated panels are adapted to connect to the frame only at one end of the panels. In another variant, the elongated panels are adapted to connect to the frame at both ends of the panels.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which like reference numerals are used to indicate corresponding parts, and in which:

Figs. 1A to 1J schematically illustrate lighting tubes and possible reflector configurations according to some possible embodiments, wherein Fig. 1A is a perspective view of one embodiment in which two elongated support elements attached to an elongated circuit board carrying light emitting elements form, an elongated "insert" of a lighting tube, Fig. IB is a cross-sectional view of a possible embodiment in which a single elongated support element having a recess extending therealong carrying the elongated circuit board, form an elongated "insert" of the lighting tube, Fig. 1C is a perspective view of another possible embodiment in which two elongated "e "-shaped support elements attached to the elongated circuit board form, an elongated "insert" of the lighting tube, Figs. ID to 1H show sectional views of support elements configured to receive and hold the elongated circuit board and implement symmetric parabolic or slanted reflector surfaces, Figs. II and 1J show sectional views of support elements configured to receive and hold the elongated circuit board and implement asymmetric reflector surfaces;

Figs. 2A to 2G schematically illustrate a lighting apparatus according to some possible embodiments, wherein Fig. 2A is a perspective view of the lighting apparatus without closing lids, Figs. 2B to 2D are side, top and side- sectional, views, respectively, of the lighting apparatus with the closing lids, Fig. 2E is a sectional-front view of the lighting apparatus with the closing lids, and Figs. 2F and 2G are sectional-front views of the lighting apparatus employing different attachment elements;

Figs. 3A to 3E schematically illustrate connection of circuit boards for construction of lighting systems having grid structures according to some possible embodiments, wherein Fig. 3A shows connection of circuit boards using attachment bays, Fig. 3B shows a sectional view demonstrating connection of circuit boards, Fig. 3C is a flowchart exemplifying a technique for connecting two circuit boards, Fig. 3D shows connection of circuit board strips at two ends of the boards, and Fig. 3E shows connection of circuit board strips at one end of the boards;

Figs. 4A to 4D schematically illustrate driving circuitries usable for driving lighting systems according to some possible embodiments, wherein Fig. 4A is a block diagram of a possible driving circuitry, Fig. 4B is an electronic diagram demonstrating a possible implementation of such a driving circuitry, Fig. 4C exemplifies another possible driving circuitry configuration, and Fig. 4D shows voltage, current and power plots obtained with the circuitry shown in Fig. 4C; and

Figs. 5A and 5B schematically illustrate a method of measuring intensity of ambient light according to some possible embodiments, wherein Fig. 5A is a time plot demonstrating a possible lighting pattern usable for carrying out the measurement and Fig. 5B is a flowchart of a possible ambient light intensity measurement procedure. DETAILED DESCRIPTION OF EMBODIMENTS

The various embodiments of the present invention are described below with reference to the figures, which are to be considered in all aspects as illustrative only and not restrictive in any manner. Elements illustrated in the drawings are not necessarily to 5 scale, emphasis instead being placed upon clearly illustrating the principles of the invention. This invention may be provided in other specific forms and embodiments without departing from the essential characteristics described herein.

Figs. 1A to 1J show improved lighting fixtures that are relatively easy to assemble and manufacture e.g. , by profile extrusion. With particular reference to Fig.

10 1A, there is illustrated a lighting tube 10 comprising an elongated tube 11 and a lighting assembly llf insertable into the tube 11. The lighting assembly llf comprises an insertable elongated support structure 12, and an elongated circuit board or strip 16 (e.g. , PCB) having a plurality of light emitting elements 14 (e.g. , LEDs) electrically connected and spaced apart along the length of the circuit board 16. Power supply wires

15 17 electrically connected to the elongated circuit board 16 extend via at least one end opening lie of the tube 11 and are connectable to an electric power source e.g. , electric power grid, for powering the light emitting elements 14. In some possible embodiments the circuit board 16 may also comprise a driving circuitry (not shown), and other constructional and/or optical elements (not shown e.g. , light dispersing lenses).

20 The elongated support structure 12, which is generally "C"-shaped in cross- section, has two elongated support elements, 12a and 12b, and an elongated light reflecting recess 12r extending along external face of the "C"-shaped support structure 12. In this example, the elongated circuit board 16 is connected in the support structure 12 between two light reflecting surfaces, 13a and 13b, of the elongated support

25 structure 12. More particularly, the elongated support structure 12 shown in Fig. 1A is made from two symmetrical elongated elements, each elongated element comprising an elongated support element (12a, 12b), a respective elongated slanted light reflecting surface (13a, 13b) configured to define the elongated recess 12r, and an elongated board gripping groove/channel (15a, 15b) horizontally extending from the elongated

30 slanted light reflecting surface (13a, 13b).

The board gripping grooves (15a, 15b) are adapted to receive and grip lateral sides of the elongated circuit board 16, thereby forming an elongated depressible lighting "insert" assembly llf that can be easily positioned and anchored inside the elongated tube 11. In this example the board gripping grooves (15a, 15b) are formed between an elongated bottom section 15m and an elongated top section 15u, wherein the bottom section 15m is of greater width. It is noted that other possible embodiments may be similarly used (e.g. , using bottom section 15m and top section 15u having 5 substantially same widths), without departing from the scope and spirit of the invention.

The elongated support elements 12a and 12b, may be of circular cross-sectional shape and fabricated by extrusion or pressure/mold casting, for example, to integrally include the slanted light reflecting surfaces, 13a and 13b, and the board gripping grooves, 15a and 15b. The elongated tube 11 may be fabricated from a transparent or

10 semi-transparent material (e.g. , polymethyl methacrylate, polycarbonate) using any suitable manufacture technique, such as but not limited to extrusion, blow molding, or the like. The elongated board 16, with the spaced apart light emitting elements 14, power supply wires 17, and any additional circuitry it may comprise (e.g. , electric driver, controller), may be manufactured using printed circuit board manufacture

15 techniques, as known to those versed in the art.

The lighting tube may be assembled by preparing the elongated support structure 12 of the insert llf with the elongated board 16 mounted therein, inserting the lighting insert llf in a pressed state into the tube 11, and releasing it inside the tube 11 to tightly fit it thereinside. The elongated support structure 12 can be assembled by attaching to

20 the lateral sides of the elongated board 16 the gripping grooves, 15a and 15b, of two symmetric support elements, 12a and 12b. Thereafter, the support elements 12a and 12b of the support structure 12 are slightly pressed one toward the other and the lighting insert llf is inserted into the tube 11 and the support elements 12a and 12b of the support structure 12 are then released thereinside such that the support elements 12a and

25 12b become pressed against the inner walls of the tube 11. For this purpose the support elements 12a and 12b may have arc cross-sectional shape configured to fit and tightly cover portions of the internal wall surface of the tube, and they may also comprise elastic/resilient materials and/or elements operative to press the support elements 12a and 12b against the internal wall of the tube 11.

30 It is noted that the elongated the circuit board or strip 16 with its light emitting elements 14 is preferably located as close as possible to the center of the tube in order to improve the stability and firmness of the insertable lighting assembly llf. Fig. IB demonstrates a possible embodiment wherein the elongated depressible support structure 12' of the lighting insert llf is made from one elongated piece of material constructed to comprise two symmetrical elongated support elements, 12a and 12b, and a symmetrical elongated light reflecting recess 12r located therebetween. As 5 seen, the light reflecting recess 12r is formed in this example by two elongated slanted light reflecting surfaces 12s and an elongated base section 12e connecting between the slanted light reflecting surface 12s. Accordingly, the elongated support structure 12' may be fabricated by extrusion/cast molding from a thermally conducting, elastic and/or light reflecting, material (e.g. , aluminum, aluminum alloy, steel), and the elongated

10 board 16 may be attached (e.g. , using glue) to the base section 12e. The elongated board circuit 16 may be manufactured by any suitable circuit manufacture technique to include the plurality of light emitting elements 14 and any additional electric circuitry and/or connectivity. One or more layers of light reflecting material may be applied over the slanted elongated light reflecting surfaces 12s and/or over the elongated base section

15 12e. The lighting insert llf comprising the support structure 12', as shown in Fig. IB, may be installed inside the tube 11, as described hereinabove with reference to Fig. 1A.

As demonstrated in Fig. 1A, the elongated support structure 12 of the lighting insert llf may be assembled from two identical/symmetrical elongated profiles attached one to the other by means of the elongated circuit board 16, and adapted to form a

20 substantially symmetric light reflecting recess 12r. Thus, the manufacture of the depressible support structure 12 requires manufacturing a single elongated profile comprising the elongated elastic support element, elongated slanted light reflecting surface, and elongated gripping groove. This support structure 12 may be configured in the form of a depressible "insert" structure whose external shape corresponds to the

25 internal shape of the tube 11, such that no fixture elements are required to hold it immobilized in place inside the tube 11 due to friction between the inner surface of the tube 11 and its elastic support elements. Thus, this lighting insert assembly does not require screws, rivets, or other elements to hold and immobilize the elongated lighting structure 12 in place once it is positioned inside the elongated tube 11.

30 Fig. IB demonstrates several features of the light tubes illustrated in Figs. 1A and IB that will be now discussed. In possible embodiments the support structure 12 of the lighting insert llf is designed to position the elongated circuit board 16 with its light emitting elements 14 at predetermined distance from the wall of the tube 11, for providing optimal illumination therefrom. For example, and without being limiting, the support structure 12 may be operable to position the board 16 at distance d from the center 11c of the tube 11, such that this distance may vary from 0 to 2/3 r in any direction {i.e., below or above the center point 11c).

5 In addition, the slant angle of the light reflecting surfaces 12s (and 13a and 13b in Fig. 1A) may be adapted to provide a beam illumination angle a of about 10° to 120°.

In some embodiments the elongated support elements 12a and 12b are designed to cover a substantial portion of the surface area of the inner walls of the tube 11, to

10 provide improved stability to support structures 12 and 12' inside the tube 11, and to improve heat sinking between the elongated board 16 and the walls of the tube 11 and the environment. For example and without being limiting, each support element 12a and 12b may be designed to extend along an arc β οϊ about 30° to 110°. For example, and without being limiting, in such possible embodiments the gap g between the free ends of

15 the support element 12a and 12b may generally be about 0.1 to 10 mm for a tube 11 having a radius r of about 32 mm.

Fig. 1C demonstrates another possible embodiment of a lighting tube device 18 comprising an elongated tube 11 and an elongated depressible lighting insert assembly llf comprised of an elongated support structure 19 having a circular "H" cross-sectional

20 shape. More particularly, in this non-limiting example, support structure 19 has a pair of top elongated support elements 19a and a pair of bottom elongated support elements 19g, which are adapted to fit the elongated support structure 19 inside the tube 11. The top and bottom elongated support elements, 19a and 19g, may comprise elastic materials or elements to obtain depressible elements permitting insertion of the structure

25 19 into the tube 11, and attachment to the inner wall of the tube, by pressure, as described hereinabove with reference to Fig. 1A. For example, and without being limiting, the elongated support elements 19a and 19g of the support structure 19 may be elastic elongated elements configured such that the shape of elongated support elements 19a and 19g is substantially straight (not shown) before being pressed inside the tube

30 11, and their circular "H" shape is obtained after being inserted into, and pressed against the inner wall of, the tube 11.

The support elements 19a and 19g are connected to support elements 19a and 19g by a connecting panel 19p, which may be implemented by a single piece of material to which the elongated circuit board 16 may be attached (e.g. , by glue), or by two separate panels connected to each other by the elongated board 16. In this non- limiting example the connecting panel 19p comprises two separate symmetric panels 19p, such that two "e "-shaped elements are formed by each pair of support elements 19a and 19g and its respective connecting panel 19p. The connecting panels 19p may each have a respective gripping elongated groove 15 adapted to receive and hold a lateral side section of the elongated circuit board 16. The connecting panel 19p may further comprise two light reflecting surfaces 19r connected therealong at the sides of the elongated board 16.

As described hereinabove with reference to Figs. 1A and IB, the elongated support structure 19 may be configured to position the elongated board 16 at a predetermined distance from the wall of the tube 11 to optimize the illumination emitted therefrom and provide a desired illumination pattern. Light reflecting surfaces 19r may be adapted to provide a desirable beam angle, such as described hereinabove with reference to Figs. 1A and IB.

Fig. ID shows a sectional view of a transparent or translucent lighting tube 11 comprising an elongated depressible insert 51 snugly fitted inside the tube 11 to position a circuit board 16 having one or more light emitting elements 14 at predetermined distance from the wall of the tube 11. The insert 51 in this example is an elongated single piece element having an arcuate (e.g. , about 270° to 330°) section 51r, and two elongated reflector surfaces 51p respectively extending from the two elongated edges 51d of the arcuate section 51r. The free end of each reflector surface 51p comprises an elongated gripping groove 15 configured and operable to receive and hold a lateral side section of the elongated circuit board 16.

As exemplified in Fig. ID, the reflector surfaces 51p may have parabolic geometrical shapes, preferably being symmetric relative to an axis of symmetry 51s of the tube 11. Thus, illumination angle φ is defined by the insert 51, and the parabolic configuration of the reflector surfaces 51p provides a substantially narrow and uniform light beam (e.g. , having a width Wl of about 15 to 50 mm) of the light emitted form the tube 11.

Figs. IE and IF demonstrate another possible configuration of a transparent or translucent elongated depressible insert 52 similar to the configuration shown in Fig. ID, but having shorter reflecting surfaces 52p. Fig. IE shows the insert 52 with the circuit board 16 loosely attached to its gripping grooves 15 before being introduced into the tube 11, and Fig. IF shows the insert 52 with the circuit board 16 firmly gripped by its gripping grooves 15 after being inserted into the tube 11, wherein the arcuate section 52r of the insert 52 is pressed against the inner wall of the tube 11. In this non-limiting 5 example the reflecting surfaces 52p are slanted surfaces designed to be pressed against the lateral side sections of the elongated circuit board 16 and provide a firm and stable grip thereof when inserted into the tube 11, as seen in Fig. IF.

Figs. 1G and 1H demonstrate an insert configuration 53 similar to that shown in Fig. IB and having two elongated gripping grooves 15 formed in the edges of its

10 elongated base section 53e. Fig. 1G shows the elongated insert 53 before being introduced into the tube 11, wherein the circuit board 16 is loosely held on the elongated base section 53e. In this state, before inserted into the tube 11, the base section 53e has a curved shape forming an elongated concave. As seen in Fig. 1H, after being inserted into the tube 11, the elongated support elements 53a and 53b of the insert

15 53 are pressed against the inner wall of the tube 11 delivering tension via the reflector surfaces 53p to the elongated base section 53e thereby substantially flattening the curvature of the base section 53e and causing the elongated gripping grooves 15 to lock onto the lateral side sections of the elongated circuit board 16 and firmly grip it.

Figs. II and 1J show lighting tube configuration having asymmetric reflector

20 arrangements. This asymmetric reflector arrangements permit reflector designs having parabolic/curved geometrical shapes that maximize focal length for a given tube size. In this way, most of the emitted light may be used for illumination, and the light losses of the tube are substantially minimized.

Fig. II shows a sectional view of a transparent or translucent lighting tube 11

25 comprising an insert 55 having an asymmetric reflector arrangement 58. The insert 55 comprises a base section 55b configured and operable to grip the elongated circuit board 16 by elongated gripping groove 15 and position it inside the tube 11 in the vicinity of the inner wall of the tube and in a predefined angle a chosen so that most (e.g. , 80-90%) of the light emitted by LEDs will be reflected by the reflector 55q. A

30 reflector surface 55q is attached to the base section 55b, facing the light emitting elements 14 mounted on the elongated circuit board 16 and spaced-apart therefrom. In this non-limiting example the reflector surface 55q is attached to an extension 55x of the base section 55b abutting a wall section of the tube, and extends from said extension 55x towards the opposite side of the tube. The gripping element 15 could optionally be implemented as a separate elongated item.

The insert 55 also comprises two elongated support members configured and operable to anchor the base section 55b and the reflector surface 55q attached to it at a desired orientation inside the tube 11. A first elongated support member 55s having an arcuate shape extends from one side of the base section 55b comprising the reflector surface 55q, and a second elongated support member 55r, also having an arcuate shape, extends from the other side of the base section 55b. The arcuate shaped support members are configured to contact and press against inner wall sections of the tube 11, to thereby cover substantial surface areas (e.g. , about 50% to 80%) of the inner wall of the tube 11 and hold the insert 55 immobilized thereinside.

The elongated reflector surface 55q is preferably of curved (e.g. , parabolic) shape, to thereby provide a substantially uniform and narrow light beam having a predetermined width (e.g. , W2 of about 15 to 50 mm). When a parabolic reflector surface is used, the light rays emitted by the light emitting elements 14 (at the focal point) are reflected by the parabolic reflector in the same direction, and the light divergence angle Θ is determined by those rays which exits the tube without being reflected. For comparison, in the symmetric design shown in Fig. ID, those rays form an angle φ that is about two times greater than the divergence angle Θ obtained using the parabolic reflector surface.

Fig. 1J shows another possible transparent semitransparent lighting tube configuration having an insert 56 configured to carry the circuit board 16 and form an asymmetric reflector configuration 59 for reflecting the light emitted from the light emitting elements 14 in a predetermined illumination pattern. The insert 56 is configured similar to the inserts 51 and 52 shown in Figs. ID to IF, but mainly different in that one of the reflector surfaces 56w is curved (concave or parabolic) while the other reflector surface 56t is substantially flat. This asymmetric reflector configuration 59 may be adjusted to provide a required illumination distribution over a plane being lit (e.g., by changing the lengths of the reflector surfaces).

The different insert configurations shown in Figs. 1A to 1J may be fabricated from an elastic material having light reflecting properties, and preferably also good hit conduction properties (e.g. , aluminum or other suitable material having the needed thermal conductivity and reflectivity). The reflector surface of the inserts may be polished, in order to achieve better light reflecting properties, and/or coated with one or more layers of light reflecting materials. The different shapes of the inserts are used to minimize the gap between the tube 11 and the insert fitted inside it, and for providing better thermal conductivity and improved heat dissipation. For this purpose the inserts are configured to change their shapes in order to conform to the inner space of the tube 11, and for locking the PCB 16 in place thereinside.

The manufacture, assembly, and installation, processes of the lighting tubes shown in Figs. IB to 1J are substantially similar to the steps described hereinabove with reference to Fig. 1A, and will not be described again herein for the sake of brevity.

After positioning a lighting insert inside the lighting tube 11, as demonstrated in

Figs. 1A to 1J, the tube 11 may be sealed by two lids (not shown) designed to cover and close the openings of the tube 11. The lids may include electrical connectors for connecting the supply wires 17 of the circuit board 16 to the electrical grid (the mains) or to a suitable driving circuitry as disclosed herein.

It is apparent from the foregoing that the lighting fixtures illustrated in Figs. 1A to 1J can be efficiently sealed to thereby obtain waterproof lighting fixtures. It is noted that other hollow bodies may be used to hermetically house the depressible support structures (12, 12' and 19) instead of the tubes 11 exemplified in Figs. 1A to 1J, having different cross-sectional shapes, such as, but not limited to, elliptical, triangular, rectangular, polygonal, and the like.

In some embodiments the elongated tube 11 implemented by a polycarbonate tube, forming the case/housing of the lighting device, may be fabricated by a coextrusion process configured to produce several illumination areas having different transparency and translucency levels designed to provide certain optical properties e.g., to provide a certain illumination pattern/profile therethrough. For example and without being limiting, the coextrusion process may be employed to fabricate a tube 11 consisting of two or three (or more) illumination surfaces having different transparency levels/properties. Alternatively, in some embodiments the tube 11 is fabricated to include four illumination surfaces, as follows: one transparent illumination surface and three diffusing illumination surfaces having different levels of translucencies. During assembly of the lighting device, the elongated support structure with light emitting elements mounted thereon can be positioned inside the elongated tube 11 relative to the different illumination surfaces/areas of the tube to achieve the desired transparency/translucency properties.

Figs. 2A to 2G schematically illustrate another possible embodiment of a lighting apparatus 40. With reference to Fig. 2A, showing a perspective view of the lighting apparatus 40 without closing lids i.e., it is shown open at both of its ends. As seen, lighting apparatus 40 generally has a horizontal cylindrical segment shape, and comprises an elongated transparent, or semi-transparent, cover 41 (e.g., made of polymethyl methacrylate, or polycarbonate), an elongated circuit board 42, and two elongated "9"-shaped fasteners 43 (also referred to herein as attachment elements e.g., made of aluminum, duralumin, or steel). In this example, cover 41 has a cross-sectional shape of a truncated circle, and the circuit board 42 is attached to the internal lateral free sides 41s of the cover 41. The circuit board 42 comprises an array of light emitting elements (14, seen in Fig. 2D to 2G) electrically connectable to an electrical power source by wires (not shown).

As better seen in Fig. 2E, the lateral sides 41s of the cover 41 have a "S"-like shape at one side and an inverted "S"-like shape at the other side, thereby forming two elongated channels 41c extending along the external sides of the cover, and two elongated internal channels 41i located below the external channels 41c and extending therealong. The internal elongated channels 41i are adapted to receive and hold the lateral sides of the circuit board 42. Referring back to Fig. 2A, the elongated fasteners 43 each comprise a rail 43h and curved leg 43e portions extending therealong. The curved leg portions 43e of the fasteners 43 form elongated channels (43c in Fig. 2E) extending therealong.

The rail portions 43h of the fasteners 43 are adapted to tightly fit into the external elongated channels 41c of the cover 41. The elongated sections of the cover 41 forming the internal channels 41i, having a generally "C"-like cross-sectional shape, are adapted to tightly fit into the elongated channels 43c formed by curved leg 43e portions of the fasteners 43, thereby fastening the lateral sides of the elongated cover 41 to the elongated circuit board 42, and enhancing the grip of the internal channel 41i over the lateral side portions of the circuit board 42.

Figs. 2B to 2D are side, top and side-sectional, views, respectively, of the lighting apparatus 40 with two closing lids 46 adapted to sealably attach over the end openings of the apparatus. With reference to Figs. 2B and 2D, in some embodiments the lids 46 comprise support sections 46u adapted for forming a gap 40c between the bottom side of the circuit board 42 (i.e. , the side without the light emitting elements 14) and a mounting surface 47 to which the lighting apparatus 40 is attached. The gap 40c obtained between the bottom side of the circuit board 42 and the mounting surface 47 permits flow of ambient air through the gap 40c and thereby facilitates removal of heat from the circuit board 42, and cooling thereof, during operation of the apparatus 40.

Figs. 2F and 2G are sectional-front views of embodiments of the lighting apparatus 40 employing different configurations of the fasteners 43 and "S"-shaped portions of the cover 41. As exemplified in Fig. 2F, the elongated fasteners 43 may comprise a support member 43k protruding upwardly from the rail portions 43h and extending along the fasteners, and the cover 41 may comprise a corresponding groove 41g extending therealong and adapted to receive the support member 43k, and thereby improve the stability/rigidity of the apparatus 40 and the grip applied by the fasteners 43 over the lateral sides of the cover 41.

Fig. 2G exemplifies another configuration of the elongated fasteners 43 comprising support rails 43b protruding upwardly from the rail portions 43h at an inner section thereof relative to the cover 41, and extending therealong. The cover 41 in this example further includes internal channels 41q formed in a top portion of the external channels 41c and adapted to tightly receive the support rails 43b and thereby improve the stability/rigidity of the apparatus 40 and the grip applied by the fasteners 43 over the lateral sides of the cover 41.

It is noted that the fabrication and assembly of lighting apparatus embodiments as exemplified in Figs. 2A to 2G is substantially simple and cost effective due to the small amounts of components required in each lighting apparatus, and due to the structural simplicity of these components.

Figs. 3A to 3D illustrate lighting grids constructed from strips of circuit boards having a plurality of light emitting elements electrically connected spaced apart along their lengths and configured to enable an automatic assembly process of planar lighting grids. Figs. 3 A to 3D also exemplify methods for quickly connecting a plurality of circuit boards one to the other in a modular fashion by means of soldering to establish a planar or curved light emitting grid. The lighting fixtures in these examples are generally comprised of a power supplying frame 23 made from one or two power supplying strips, and a plurality of lighting board strips 21 connectable to the power supplying frame 23.

Each lighting board strip 21 has one or two soldering composition pads (generally referenced by numeral 22) deposited on an end section thereof (with or 5 without vias/holes). The power supplying frame 23 has electrical conductors connectable to a power source (not shown, e.g. , electric grid) and it is provided with a plurality of pass-through holes (vias) spaced apart along its length, each hole having a metal pad electrically connected to at least one of the electrical conductors and encircling part, or the entire, perimeter of the hole.

10 With reference to Fig. 3A, there is illustrated a lighting grid 27a comprising a power supplying frame 23 having soldering bays (only two bays 24a and 24b are shown), and a lighting board strip 21 having a respective pair of soldering composition pads 22a and 22b, and light emitting elements 14 (only one light emitting element is shown). The soldering bays 24a and 24b may comprise soldering material compositions

15 (not shown), or alternatively, soldering material compositions may be introduced into the soldering bays 24a and 24b during the process of attaching the lighting board strip 21 to the power supplying frame 23. It is noted that in possible embodiments the number of soldering bays provided in the power supplying frame 23, and the number of respective soldering bays provided on the lighting board strips 21 may be greater than

20 two, and they may be arranged in any suitable geometrical form to provide the needed connectivity and alignment.

Fig. 3B is a cross-sectional view demonstrating attachment of a lighting board strip 21 to a power supplying frame 23 having a plurality of soldering bays/vias (holes) 23v. As shown, lighting board strip 21 comprises a plurality of light emitting elements

25 14 electrically connected by conducting line 26 to a soldering pad 22 deposited on the board strip 21. A corresponding electrically conductive circular pad 25p, electrically connected to line conductor 23c of the power supplying frame 23, and adapted to mate with soldering pad 22, encircles at least a portion of a perimeter of via 23v. In this non- limiting example, circular pad 25p is adapted to encircle the via 23v at both sides of the

30 frame 23, but in possible embodiments circular pad 25p may be adapted to encircle the via 23v at one (top or bottom) side of the frame 23.

With reference to the flow chart shown in Figs. 3C, in some possible embodiments the attachment of the lighting board strips 21 to the power supplying frame 23 is commenced (step si) by placing them one on top of the other, and then (step s2) aligning the lighting board strip 21 with the power supplying frame 23 by mating the soldering pads 22 with the soldering vias/bays 23v. A specially designed holder device may be used to fixate the aligned elements 21 and 23, if so needed. Next (step s3), soldering material composition 25 (e.g. , soldering paste) is introduced (e.g. , by injection) into the soldering vias/bays 23v. However, it is noted that the soldering material composition 25 may be introduced into the soldering vias 23v during the preparation of the frames 23, and in this case this step (s3) may be skipped.

The soldering material compositions in the vias 23v and on the lighting board strip 21 are heated (step s4) to their melting temperatures, and then (step s5) the heated soldering material compositions in the vias/bays 23v and on the lighting board strip 21 are combined, cooled and solidified, and thereby establish electrical and mechanical connectivity between the power supplying frame 23 and the lighting board strip 21. More particularly, the mechanical connection is obtained by the bonding the frame 23 and strip 21 together by combining the soldering material compositions inside the vias/bays 23v and of the pads 22, which also provide electrical connections between the conducting line 26 and the circular pad 25p, which thereby electrically connects the light emitting elements 14 of the strip 21 to the line conductor 23c of the power supplying frame 23. Various fixture elements may be used in addition to the soldering material compositions in order to improve the mechanical and/or electrical properties of the connection.

It is noted that the process illustrated in Fig. 3C may be performed manually, by a machine, robot or other automated device.

In possible embodiments soldering bays and/or vias may be formed in the lighting board strips 21 electrically connected to their conducting line 26, and the soldering pads 22 may be formed on the power supplying frames 23, electrically connected to their line conductor 23c. In yet other possible embodiments a combination of soldering bays/vias and pads may be formed on the lighting board strips 21, and a complementary soldering bays/vias and pads arrangement may be formed on the power supplying frames 23 configured to facilitate the alignment therebetween and the required electrical and mechanical connection.

Fig. 3D schematically illustrates construction of a lighting grid 27b according to some possible embodiments wherein the lighting board strips 21 are connected at both ends to power supplying strips of the frame 23 comprised of two power supplying strips 23a and 23b. Fig. 3D shows the lighting board strips 21 and the power supplying strips 23a and 23b of the lighting grid 27b before they are soldered to assemble a single lighting grid unit 27b. Each power supplying strip (23a, 23b) comprises a plurality of vias 23v spaced apart along its length and electrically connected to the electrical conductor line 23c of the strip, and each via 23v comprises a circular electrically conducting pad 25p electrically connected to the conductor line the 23c. The lighting grid 27b comprises a plurality of lighting board strips 21, each comprising a plurality of light emitting elements 14 electrically connected to soldering pads 22a and 22b.

More particularly, in each lighting board strip 21 the soldering pad 22a provided at one end section of the strip 21 is electrically connected to the light emitting elements 14 through electric conductor line 26a passing along a substantial portion of its length, and the soldering pad 22b provided at the other end section of the strip 21 is electrically connected to the light emitting elements 14 through electric conductor line 26b also passing along a substantial portion of its length. In this non-limiting example each electric conductor line (26a, 26b) is passing on the top surface and adjacent one of the lateral sides of the strip 21, while the light emitting elements 14 are mounted between the conductor lines 26a and 26b. However, any other suitable arrangement of the light emitting elements 14 and conductor line 26a and 26b may be used (e.g. , passing one conductor line, or both lines, on the bottom surface of the strip).

The attachment of the lighting board strips 21 to the strips 23a and 23b of the power supplying frame 23 is substantially similar to the soldering process described hereinabove with reference to Fig. 3C. The soldering process may be started by first connecting the lighting board strips 21 to one power supplying strip (e.g. , 23a) and thereafter to the other (e.g. , 23b), or by simultaneously connecting the lighting board strips 21 to both power supplying strips 23a and 23b. After completing the soldering process the lighting grid 27b may be activated by connecting the power supplying frame 23 to a power source through the conducting wires 23d electrically connected to the conductor lines 23c of the frame through the feeding ports 23p.

Fig. 3E shows another possible embodiment of a lighting grid 27c wherein the power supplying frame 23 comprises a single strip 23'. Fig. 3E shows the lighting board strips 21' and the power supplying strip 23' of the lighting grid 27c before they are soldered to assemble a single lighting grid unit 27c. In this embodiment, the power supplying strip 23' comprises a plurality of via pairs 23s spaced apart and electrically connected along the strip 23', and two respective electric conductor lines 23f and 23r adapted to electrically connect between respective vias of the vias pairs 23s. For example, and without being limiting, in Fig. 3E the top via of each vias pair 23s is connected to conductor line 23f, and the bottom via of each vias pair 23s is connected to conductor line 23r, and the vias pairs 23s are located between the conductor line 23f and 23r.

The lighting board strips 21' in this embodiment comprise a plurality of light emitting elements 14 electrically connected through electric conductor lines 26a and 26b to respective pair of soldering pads 22s, which are provided at one end section of the strips 21'. The light emitting elements 14 and the conductors 26a and 26b may be arranged on the board strips in a way similar to that described with reference to Fig. 3D, or in any other suitable way (e.g. , passing one conductor line, or both lines, on the bottom surface of the strip).

The soldering process of lighting grid 27c is substantially similar to the soldering process described hereinabove with reference to Fig. 3C, carried out by mating the pair of soldering pads 22s of each lighting board strip 21' with a respective pair of vias 23s of the frame 23' and heating the soldering material compositions to a melting temperature, and thereafter letting it cool and solidify. After completing the soldering process, the lighting grid 27c may be activated by connecting the power supplying frame 23' to a power source through the conducting wires 23d electrically connected to the conductor lines 23f and 23r of the frame through the feeding ports 23p.

In possible embodiments the lighting board strips 21' may comprise an additional (not shown) pair of soldering pads 22s provided at the other end section of the strips 21' and electrically connected to the conductor lines 26a and 26b, adapted to permit connecting the strips 21' at any, or both, of their sides, to power supplying strips 23a and 23b, as described hereinabove with reference to Fig. 3D, if so needed. In possible embodiments of the lighting grids 27b and 27c shown in Figs. 3D and 3E, the pads may be formed on the power supplying frame and the corresponding soldering vias may be formed on the lighting board strips.

In possible applications, the power supplying frame 23 may comprise a driving circuitry operable to receive electric power supply from the electric network and regulate driving electric power supplied to the light emitting elements 14. The power supplying frame 23 may comprise a control unit (not shown) configured and operable to control operation of the light emitting elements 14, and/or a driving circuitry if so needed.

In some embodiments the lighting strip boards (21 and/or 21'), may optionally be implemented as a single layer board, and the power supplying strips (23, 23a, 23b, and/or 23') may be optionally implemented as double-layered boards. Optionally, the power supplying frame also comprises a plurality of light emitting elements mounted spaced apart therealong.

Fig. 4A is a block diagram illustrating an electric driver circuitry 30 designed for powering direct current (DC) light emitting elements 36, such as, but not limited to, LEDs. The electric driver circuitry 30 utilizes a constant current source (CCS) 34 for powering the light emitting elements 36 and a capacitive element 35 (e.g. , dielectric or electrolyte capacitor) for adjusting voltage drop across the CCS 34. A voltage controlled current source (VCCS) 32 is used for charging the capacitive element 35 with electric charges received from a rectifier unit 31. The rectifier 31 may be coupled to an electric network 31m directly or via a transformer (not shown). A feedback branch 33 connecting between the CCS 34 and the VCCS 32 is configured and operable to regulate the charging of the capacitive element 35 by the VCCS 32, prevent voltage fluctuations of the capacitive element 35 and minimize current ripples in the current supplied to the light emitting elements 34.

The CCS 34 may be implemented as a regulated or unregulated constant current source. In order to obtain maximal power factor and efficiency, the design of electric driver circuitry 30 in some embodiments guarantees that the voltage drop across the CCS 34 is maintained as low as possible, and that the charging current of the capacitive element 35 during each half-cycle of the mains power supply frequency be constant.

The driver circuitry 30 may comprise a control unit 37 configured and operable to control actuation of the light emitting elements 36 e.g. , by controlling the operation of the VCCS 32. The control unit 37 may comprise a processor 37u and one or more memories (e.g. , RAM, ROM, EPROM, Flash) 37m for storing data and software instructions executable by the processor 37u. The control unit 37 may be configured and operable to set the level of illumination that the light emitting elements 34 produce (e.g. , implement dimmer utility), to selectively activate some (or all) of the light emitting elements 36 and deactivate the others, determine ambient light intensity and control the operation of the light emitting elements 36 accordingly. In some embodiments a sensor unit 37s is used by the control unit 37 for measuring the ambient light intensity in a vicinity of the light emitting elements 36 and generating data indicative thereof.

In some embodiments the control unit 37 is configured to measure the voltage drop across the CCS 34 (e.g. , using an analog to digital converter - not shown) and set a control voltage/signal (e.g. , gate voltage) of the VCCS 32 accordingly. In such embodiments the control unit 37 is configured to set the control voltage of the VCCS 32 according to measurements carried out during operating cycle time durations that are equal to the half -cycle duration of the mains voltage (31m) frequency cycle time (0.5/F, e.g. , 0.01 seconds for 50 Hz). In each operating cycle the control unit 37 measures the voltage across the VCCS 32 and determines a minimum VCCS voltage drop. If the control unit determines that the minimum VCCS voltage drop differs from a preset voltage level, the control unit 37 calculates a suitable adjustment control voltage for adjusting the charging current supplied by the VCCS 32 to the capacitive element 35. The control unit 37 then applies the calculated adjustment control voltage to the VCCS 32 (e.g. , to a gate terminal of the VCCS using a digital to analog converter - not shown) during the successive operating cycle, and carry out VCCS voltage measurements for adjustment of the control voltage to be applied during the next operating cycle.

For example, and without being limiting, the control unit 37 may be configured to continuously set the control voltage of the VCCS 32 in order to maintain a desired voltage level on the capacitive element 35, said desired voltage level being typically smaller than the voltage supplied to the driving circuitry 30 by the mains 31m. The VCCS 32 maintains the desired voltage level over the capacitive element 35 by monitoring the voltage level across the CCS 34 and adjusting the charging current supplied to the capacitive element 35 accordingly. When the instantaneous voltage on the CCS 34 is greater than the desired voltage level (e.g. , greater than some predefined threshold level), the control unit 37 sets the control voltage of the VCCS 32 during the next operating half-cycle to decrease the charging current supplied to the capacitive element 35 through the VCCS 32. Accordingly, the voltage on the capacitive element 35 remains substantially constant during this time as set by the control voltage set by the control unit 37. When the measured instantaneous voltage level of the CCS 34 is smaller than the voltage level measured during the previous half-cycle, the control unit 37 sets the control voltage to be applied to the VCCS 32 during the next half-cycle to increase the charging current supplied to the capacitive element 35 through the VCCS 32.

Optionally, and in some embodiments preferably, the driving circuitry 30 is configured to keep the voltage level across the CCS 34 as low as possible, but not lower than some predefined value, so as to maintain some predefined desired voltage level over the CCS 34. In order to increase efficiency it is desirable that the voltage across the CCS 34 be as low as possible, but greater than zero.

It is therefore preferable in some embodiments to compare the measured voltage level of the CCS 34 to predefined threshold levels defining a desirable voltage range of the CCS 34. For example, and without being liming, the desirable voltage range of the CCS 34 may be defined between high (¼,_¾¾) and low (V _ow< V_hi_gh) threshold levels such that whenever the measured voltage (V_ccs) of the CCS 34 is greater than the high threshold level (V_ccs>V_hi_gh) the control unit 37 sets the control voltage of the VCCS during the next half-cycle to decrease the charging current supplied to the capacitive element 35, and when the measured voltage of the CCS 34 is smaller than the low threshold level (V_ccs<Vi_ow) the control unit 37 sets the control voltage to be applied to the VCCS 32 during the next half-cycle to increase the charging current supplied to the capacitive element 35 through the VCCS 32.

The driver circuitry 30 can be used to obtain high power factor and efficiency without requiring high-frequency conversion functionality. The operation of driver circuitry 30 proceeds even in case of a significant decrease in the voltage over the capacitive element 35. Furthermore, driver circuitry 30 is capable of providing nearly constant power factor and efficiency in a wide range of output powers. The control unit 37 may be implemented by a microcontroller device comprising one or more processing and memory utilities, such as, for example, AVR (of Atmel Corp.), PIC (of Microchip Technology Inc.) or STM8 (of STMicroelectronics) microcontrollers.

Fig. 4B exemplifies a possible embodiment of the driver 30 illustrated in Fig. 4A. As seen, the diode bridge rectifier 31 feeds the voltage controlled current source 32, which may be implemented as a common drain amplifier. For example, amplifying device 32t (e.g. , N-channel MOSFET) may be connected to the rectifier 31 at drain terminal thereof and adapted to receive gate signals from the rectifier 31 as set by the resistive-capacitive circuitry comprised of resistor 32r, connecting between the rectifying bridge 31 and the gate terminal, and of the capacitor 32c, connected between the capacitive element 35 and the gate terminal. The output of the VCCS 32 may be provided to the capacitive element 35 through the resistive element 32n (e.g. , connected 5 to the source terminal). In some possible embodiments the CCS 34 may be implemented by means of NSI45030 (ON Semiconductor) or LM317 devices, or by a simple 2- transistor constant current source implementation (e.g. , current mirror circuit).

In this embodiment the control voltage of the VCCS 32 is further controlled by the capacitor 32c, whose capacity (CI) may be relatively high (e.g. , in the range of 1 to

10 50 microfarads). The VCCS 32 may be implemented using a transistor based amplifying device 32t and the resistive element 32n connected to a source terminal thereof.

The capacitor 32c is charged through the resistor 32r, whose electrical resistance (Rl) may be relatively high (e.g. , about 100 to 500 KiloOhms). As seen in Fig. 4B, the resistor 32r is connected to the positive output of the bridge rectifier 31. If the voltage

15 across the constant current source 34 decreases, the capacitor 32c begins to charge through the resistor 32r with the electric charges received from the bridge rectifier 31. Responsively, the charge current of the capacitive elements 35 increases, and the voltage across it also increases. As a result, the voltage over the constant current source 34 also increases and thus returns to the desired voltage value range.

20 The driver circuitry exemplified in Fig. 4B may comprise a compensation branch 33 comprised of resistor 33r connected in series to a capacitive circuitry comprised of capacitor 33c and Zener diode 33d which are electrically connected to each other in parallel. In this non-limiting example the compensation branch connects between the light emitting elements 36 and the control terminal 32c of the amplifying

25 device 32t. The electrical resistance (R2) of resistor 33r of the compensation branch 33 (in series with the Zener diode D2) should be substantially smaller than the electrical resistance (Rl) of the resistor 32r used to charge the capacitor 32c. At the same time, the electrical resistance (R2) of resistor 33r should be sufficiently high to guarantee that the time constant R2*C1 be sufficiently greater than half-cycle time duration of the

30 supply voltage.

The driver circuitry exemplified in Fig. 4B may fail to react if the supply voltage 31m decreases too fast and the speed of charge of the capacitor 32c through the resistance 32r is insufficient to compensate this change. In this case the control voltage of the amplifying device 32t will be temporarily powered from the capacitor 33c of the compensation branch 33, connected in parallel with the Zener diode D2. When the capacitor 32c is charged back to the desired voltage, the driving circuitry will return to its normal state of operation.

In some embodiments the capacitor 32c and resistor 32r may be connected to the control terminal 32c of the amplifying device 32t through a diode device 32d (Dl). In this non-limiting example the anode terminal of the diode device 32d is electrically connected to the resistor 32r and capacitor 32c, and the cathode terminal of the diode device 32d is electrically connected to the control terminal 32c of the amplifying device 32t and to the compensation branch 33.

In this way the driver circuitry also provides acceptable stabilization of the voltage drop across the constant current source 34, however providing lower power factor and efficiency than embodiments wherein only control unit 37 is used to control the control voltage of the amplifying device 32t.

Both driver circuitry embodiments provide stability of power factor, efficiency in wide output power ranges, and high reliability, achieved due to absence of transient processes with high voltage and current values, and, as a consequence, absence of high- frequency electromagnetic radiation. Other advantages of these embodiments are, simplicity, low element count, low cost, absence of transient voltage and current surges, very low ripple, and high power factor and efficiency in wide output power ranges. Furthermore, there is no high-frequency voltage and current ripple on the capacitive element 35, therefore the lifetime of capacitive element 35 is prolonged, as compared to conventional circuitries employing high-frequency regulation/conversion.

Embodiments of the driver circuitries described above provide efficiency ranging from 0.8 to 0.85 and a power factor ranging from 0.85 to 0.9, and they are suitable for using high-efficiency LEDs (e.g. , 180 lm/W at present) as the light emitting elements 36, while providing very low LED current ripple. It is noted that the above described driver circuitries do not require any special types of LEDs, e.g. , high-voltage LEDs. It is noted that the driving circuitries exemplified in Figs. 4A and 4B are not limited for use with direct current light emitting devices, and that these driving circuitries may be advantageously used for the powering of other electrical/electronic devices requiring a stabilized DC power supply. Fig. 4C shows a driving circuitry 39 usable for powering an array of light emitting elements 36 (also referred to herein as load e.g. , LEDs), according to some possible embodiments. The driving circuitry 39 comprises the following current sources: (i) a voltage controlled current source 38t (e.g. , using a MOSFET); and (ii) a constant current source 38s (CC2, e.g. , regulated/unregulated constant current source). The voltage controlled current source 38t is electrically connected to a rectifying circuitry 31 (e.g. , diode bridge), and electrically coupled to the constant current source 38s. The constant current source 38s is electrically connected to the light emitting elements 36 for electrically powering them, and further provides control signals to the voltage controlled current source 38t via the feedback line 38p.

A capacitive element 35 electrically connected in parallel to the load branch 35d comprising the constant current source 38s and the load/light emitting elements 36, is used for adjusting voltage drop across the constant current source 38s. The voltage controlled current source is configured and operable to controllably supply charging currents to the capacitive element 35 according to the control signals received from the constant current source 38s. In this non-limiting example the operation of the voltage controlled current source 38t is controlled by voltage signals received from the constant current source 38s, said voltage signals being proportional or substantially equal to the electrical voltage across the constant current source 38s.

In this way, changes in the voltage of the capacitive element 35 during operation of the driving circuitry 39 cause corresponding/proportional changes in the control signals supplied to the voltage controlled current source 38t via the feedback line 38p. The changes of the control signals supplied via the feedback line 38p cause respective changes in the electrical current I_Ki supplied by the voltage controlled current source 38t to the capacitive element 35 and the parallel load branch 35d, to thereby compensate the changes in the voltage of the capacitive element 35.

As exemplified in Fig. 4C the voltage controlled current source 38t may comprise a MOSFET. In this example the MOSFET is configured and operable to receive electrical power from the rectifying circuitry 31 via its drain terminal (D), receive the control signals from the feedback line 38p via its gate (G) terminal, and supply electrical current to the capacitive elements 35 and the parallel load branch 35d via its source terminal (S). In some embodiments, the driving circuitry 39 shown in Fig. 4C can provide a theoretical maximum efficiency of about 0.85, and a power factor of about 0.85. In some applications, employing a rated input voltage, a power factor about 0.86 - 0.87, and efficiency of about 0.79 - 0.81, can be obtained, due to voltage ripples presented in the voltage over the capacitive element 35.

The rectifying circuitry 31 may be coupled to the electric (grid) network 31m directly, or via a filtering circuitry (31d) as exemplified in Fig. 4C. In some possible embodiments a resonant filter 31d (e.g. , LC filter) can be used to increase the efficiency and power factor of the driving circuitry 39. In this non-limiting example the resonant filter 31d comprises an inductor (L) 31i, connected in parallel to a first capacitor (CI) 31c, and a second capacitor (C2) 3 If connected in series to the parallel circuitry of the inductor 31i and the first capacitor 31c. The rectifying circuitry 31 is electrically linked to the second capacitor 31f, which supplies an electrical current with corrected waveform to rectifying circuitry 31.

Optionally, and in some embodiments preferably, the resonant filter circuitry

31d is configured and operable to substantially attenuate one or more harmonics induced by the load 36 and/or the driving circuitry in order to prevent them from influencing the electric grid supply power. For example, in some embodiments, the resonant filter circuitry 31d is configured and operable to filter out the third (and possibly higher) harmonic of the frequency of the electric grid supply.

In operation, when electrical current starts to flow through the voltage controlled current source 38t, the resonant filter circuitry 31d begins to accumulate energy that substantially attenuates the level of third harmonic of the electrical power grid supplied to the voltage controlled current source 38t via the rectifying circuitry 31. This effect is achieved due to the resonant filter circuitry 31d being configured to function as a rejector circuit for the electric grid frequency. At the middle of the half-period, the electrical grid current (31m) changes its direction, which causes a decrease of the voltage drop across the voltage controlled current source 38t, thus reducing the dissipated power and increasing efficiency. Closer to the end of the half -period, when the electric grid current (31m) changes its direction once more, the level of third harmonic of the electric grid frequency is attenuated again to increase efficiency.

It is noted that the resonant filter circuitry 31d may be similarly used in the driving circuitries shown in Figs. 4A and 4B. In some embodiments the power factor of the driving circuitry 39 utilizing the resonant filter circuitry 3 Id was increased to a level higher than 0.94, while decreasing the power of the third harmonic of the frequency of the electric grid supply 31m by a factor of 5 (i.e. , about 20% reduction). The efficiency of the driving circuitry 39 utilizing the resonant filter circuitry 31d was increased by 5 about 5-7%.

Fig. 4D shows at 41 plots of electrical current (Ικι), voltage (UKI) and power (wattage, P_Ki = UKI * Ικι) waveforms across the voltage controlled current source 38t without the resonant filter circuitry 31d, and at 42 with the resonant filter circuitry 31d. As seen, the resonant filter circuitry 31d improves power factor of the driver circuitry 10 39.

Fig. 5A demonstrates a method for measuring ambient light intensity using a light detector (sensor unit 37s), according to some possible embodiments. The ambient light intensity measurements may be used for selective activation of the light emitting elements e.g. , for turning the light emitting elements ON whenever determining that the

15 intensity of the ambient light is sufficiently low (e.g. , about 0-2 lux), and turning them OFF whenever determining that the intensity of the ambient light is sufficiently high (e.g. , about 500-1000 lux).

Typically, ambient light intensity is measured using light sensors embedded in the lighting device, such that the measurement is affected by luminous flux of the light

20 produced by the light emitting elements. When turning the lighting device ON, the ambient light intensity around it increases, which may influence the light detector and cause false detection of high ambient light conditions. This problem is typically solved by optically isolating the lighting device from the light detector, which is not always suitable and typically complicates design considerations of the lighting system.

25 The solution demonstrated in Fig. 5A suggests periodically turning the lighting device OFF (P„) for sufficient time duration T„ (e.g. , about 1 millisecond) for carrying out the measurement, and measuring the ambient light intensity during these time durations T„ when no light is emitted from the lighting device, to thereby exclude measurement artifacts introduced due to the light emitted from the lighting device.

30 However, despite the low OFF-time T„ required for measuring the ambient light intensity, the human eye can still detect it, resulting in noticeable light flickers.

To substantially reduce, or entirely eliminate, visibility of such light flickers, a sequence of illumination stoppages/deactivations Pi, P2, P3, . . . preceding the illumination stoppage/deactivation P„ is performed, starting with a minimum illumination stoppage/deactivation time

that is so small (e.g. , about 1 microsecond) that it cannot be perceived by a human eye, where the stoppage/deactivation time T, (where is an integer, 2<i<n) of each successive illumination stoppage P, is gradually increased (Τι< Ύι< Ύτ,<. ..<T„), until the sufficient time duration T„ for measuring the ambient light intensity is reached.

During the illumination stoppage/deactivation P„ one or more measurements of the ambient light are made by the sensor unit 37s, which are then used by the control unit 37 to determine the ambient light intensity. After measuring the ambient light during the P„ illumination stoppage/deactivation a sequence of illumination stoppages/deactivations P_n+i, P_n+2, ·■·, are performed with gradually decreasing time stoppages/deactivations (T_n>T_n+i>T_n+2>. . .>T2_n-i-=T_mi_n) until reaching the minimal illumination stoppage/deactivation time T_mi„.

Fig. 5B is a block diagram exemplifying a process for measuring ambient light intensity according to some possible embodiments. Following a period of normal illumination (step ql) at some predetermined illumination level, a measurement sequence is commenced (step q2) by setting the parameters for illumination time duration (T), Off-time (T_s - illumination stoppage time), time delta (At) for incrementing or decrementing consecutive illumination stoppages, and for the minimal illumination stoppage time (Tmin). If the illumination stoppage time T_s is smaller than the minimum stoppage time (step q3) the control is passed to normal illumination (step ql). The initial illumination stoppage time T_s should be equal, or slightly greater than, the minimum illumination stoppage time Tmin, such that illumination by the system should continue during the ON time of T-T_s (in steps q6-q7).

Once the ON time lapses, illumination stoppage duration commences, and the light emitting elements are deactivated (step q8). Illumination stoppage continues as long as illumination stoppage time T_s had not lapsed (step q9), and if it is determined during the stoppage time that the illumination stoppage time T_s is not smaller than the sufficient time duration T„ for carrying out the ambient light measurements (step qlO), then ambient light measurements are performed (in step qll). Once the illumination stoppage time T_s lapses, if the stoppage time T_s is smaller than the sufficient time duration for measurement T„, which means that the sufficient stoppage time duration for carrying out the measurements was not yet reached, then the stoppage time T_s is incremented by the time delta At (steps q5 and q3).

Otherwise, if the stoppage time T_s is not smaller than the sufficient time duration for measurement T„, which means that ambient light measurements were performed during the last stoppage T„ and stoppage time duration should be progressively decremented, the time delta value is negated (At -At) and the stoppage time T_s is decremented by the time delta At (steps q5 and q4 followed by step q3). The negation of the time delta At is performed once during each measurement cycle, and thereafter gradual reduction of the illumination stoppage time T_s is carried out during the following sequence of illumination stoppages (steps q6 to q9), as long as the illumination stoppage time T_s is greater than the minimum stoppage time T_mi_n (step q3). Once the stoppage time T_s is no longer greater than the minimum stoppage time Ύ the illumination stoppage cycle is terminated by passing the control back to normal illumination (steps ql).

It is noted that the total time duration of the measurement cycles, starting from the first illumination stoppage Pi until the last illumination stoppage T2_n-i, should be sufficiently longer than the time of persistence of vision of a human eye (e.g. , about 100 to 500 msec). The time between consecutive measurement cycles (i.e. , the normal illumination period in step ql) depends on the desired reaction time for a given design.

This ambient light intensity measurement technique simplifies design considerations of the lighting device, and decreases the construction costs because it requires no optical isolation between the light emitting elements and the light detector. Additionally, this measurement technique permits locating the light detector on the same circuit board of the control and driving circuitries, thus eliminating the need for an external connection and fixture for the light detector.

Various features discussed above may optionally be combined with one another. For example, a single device may be constructed to include the lighting tube (as described with reference to Figs. 1A to 1J) and/or the lighting grid structure (27a, 27b or 27c, as described with reference to Figs. 3A to 3E), the driving circuitry 30 or 39, the control unit 37 and sensor unit 37s (as described with reference to Figs. 4A to 4C). Alternatively, these individual features can be used separately. For example, the driving circuitry 30 or 39 can be used in the lighting tube or grid which does not incorporate the control unit 37 and/or the sensor unit 37s.

A control unit 37 suitable for use with embodiments described hereinabove may include, for example, one or more processors 37u connected via a communication bus to one or more volatile memories (e.g. , random access memory - RAM) or non-volatile memories (e.g. , Flash memory). A secondary memory (e.g. , a hard disk drive, a removable storage drive, and/or removable memory chip such as an EPROM, PROM or Flash memory) may be used for storing data, computer programs or other instructions, to be loaded into the control unit 37.

For example, computer programs (e.g. , computer control logic) may be loaded from the secondary memory into a main memory for execution by one or more processors of the control unit 37. Alternatively or additionally, computer programs may be received via a communication interface. Such computer programs, when executed, enable the control unit 37 to perform certain features of the present invention as discussed herein. In particular, the computer programs, when executed, enable a control processor 37u to perform and/or cause the performance of features of the present invention. Accordingly, such computer programs may implement controllers of the computer system.

In an embodiment where the invention is implemented using software, the software can be stored in a computer program product and loaded into the control unit 37 using the removable storage drive, the memory chips or the communications interface. The control logic (software), when executed by a control processor 37u, causes the control processor 37u to perform certain functions of the invention as described herein.

In another embodiment, features of the invention are implemented primarily in hardware using, for example, hardware components such as application specific integrated circuits (ASICs) or field-programmable gated arrays (FPGAs). Additionally or alternatively, a hardware state machine may be used to implement functions described herein, as will be apparent to persons skilled in the relevant art. In yet another embodiment, features of the invention can be implemented using a combination of both hardware and software.

As described hereinabove and shown in the associated Figs., the present invention provides arrangements and structures of efficient and relatively low cost lighting devices operated by DC voltage, and related methods for constructing and operating them. While particular embodiments of the invention have been described, it will be understood, however, that the invention is not limited thereto, since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. As will be appreciated by the skilled person, the invention can be carried out in a great variety of ways, employing more than one technique from those described above, all without exceeding the scope of the invention.

Claims

CLAIMS:

1. A lighting system comprising a driving circuitry electrically connectable to a lighting apparatus, said driving circuitry comprising a constant current source for powering the lighting apparatus and a stabilizing circuitry electrically coupled to the constant current source for adjusting the voltage over said constant current source, said stabilizing circuitry comprising at least one capacitive element and a controlled current source operable for controllably charging said at least one capacitive element so as to maintain a substantially constant electrical power supply of the lighting apparatus.

2. The system of claim 1 comprising a feedback circuitry coupling between the stabilizing circuitry and the controlled current source for regulating the charging current of the at least one capacitive element.

3. The system of claim 2 wherein the feedback circuitry is configured and operable to provide the stabilizing circuitry control signals being substantially proportional to an electrical voltage of the constant current source.

4. The system of any one of the preceding claims comprising a compensation circuitry coupling between the lighting apparatus and the stabilizing circuitry, said compensation circuitry being operable to compensate for fluctuations in the electrical power supply supplied to the stabilizing circuitry.

5. The system of claim 4 wherein the compensation circuitry comprises a resistive element connected in series to a capacitive circuitry comprised of a capacitor and a

Zener diode electrically connected in parallel to each other.

6. The system of any one of the preceding claims comprising a rectifying circuitry for rectifying electric power supplied to the stabilizing circuitry.

7. The system according to any one of the preceding claims comprising a filtering circuitry configured and operable to substantially attenuate one or more harmonics of a frequency of electric power supplied to the stabilizing circuitry and thereby improve power factor of the system.

8. The system of any one of claims 2 to 7 wherein the feedback circuitry comprises a capacitor coupling the at least one capacitive element to the controlled current source of the stabilizing circuitry.

9. The system of any one of the preceding claims comprising a control unit configured and operable to adjust control signals of the controlled current source according to a voltage over the constant current source and to thereby adjust the charging of the at least one capacitive element accordingly.

10. The system of claim 9 comprising a light detector, said control unit configured to receive measurement data from said light detector, determine intensity of ambient light in a vicinity of the lighting apparatus, and regulate electric power supplied to the lighting apparatus accordingly.

11. The system of claim 10 wherein the control unit is configured to deactivate the lighting apparatus during its operation for an adequate duration of time for measuring ambient light intensity by the light detector, and thereafter turn it back to its operating state.

12. The system of claim 11 wherein the control unit is configured to sequentially deactivate the lighting apparatus for progressively increasing time durations, starting from a minimal time duration, until reaching the adequate time duration during which the ambient light intensity is measured, and thereafter to deactivate the lighting apparatus for progressively decreasing time durations, until the minimal time duration is reached.

13. The system of any one of the preceding claims configured to provide power efficiency in the range of 0.8 to 0.85 and a power factor in the range of 0.85 to 0.9.

14. The system of any one of the preceding claims configured to maintain very small ripples in the driving current supplied to the lighting apparatus.

15. The system of any one of the preceding claims wherein the lighting apparatus comprises:

an elongated circuit board having electrical conductors electrically connectable to an electric power source; an array of light emitting elements mounted on said circuit board and electrically connected to said electrical conductors;

an elongated transparent, or semi-transparent, cover having a rounded cross- sectional shape defining inner and external surfaces of said cover, said inner surface comprising gripping sections each extending along and adjacent a lateral side of the cover and connecting a lateral side of the circuit board to the cover, said external surface comprising fastening sections each extending along a lateral side of the cover and adjacent to one of the gripping sections; and

elongated attachment elements, each connected to one of the fastening sections of the cover and being adapted to fasten the connection established between the adjacent gripping section and the lateral side of the circuit board.

16. The system of claim 15 comprising lids adapted to attach over and close openings formed at the extremities of the lighting apparatus.

17. The system of claim 16 wherein each one of the lids comprises a support section for holding an end extremity section of the circuit board and thereby forming a gap between the circuit board and a surface on which said lighting apparatus is to be mounted.

18. The system of any one of claims 15 to 17 wherein at least one of the gripping sections comprises an elongated channel operable to receive and hold a lateral side of the circuit board.

19. The system of any one of claims 15 to 18 wherein at least one of the fastening sections comprises an elongated channel and wherein at least one of the attachment elements comprises a respective elongated rail section tightly fitted inside said elongated channel.

20. The system of claim 19 wherein at least one of the attachment elements comprises a support member protruding from the rail section and extending therealong and wherein the fastening section comprises a respective elongated groove adapted to receive said support member.

21. The system of claim 19 wherein at least one of the attachment elements comprises a supporting member protruding from the rail section and extending therealong and wherein the elongated channel of the at least one of the fastening sections comprises a respective internal channel extending therealong and adapted to receive said supporting member thereinside.

22. The system of any one of claims 1 to 14 wherein the lighting apparatus comprises a transparent or semi-transparent tube and a depressible insert assembly position inside said tube, said insert assembly comprising:

an elongated circuit board having electrical conductors connectable to an electric power source;

an array of light emitting elements mounted on the circuit board and electrically connected to its electrical conductors;

an elongated supporting structure having an elongated base section extending therealong and adapted for receiving and mounting the elongated circuit board thereon, and supporting elements at lateral sides of said elongated base section, said supporting elements configured to engage internal surfaces of the tube and enable fitting said elongated supporting structure inside said tube.

23. The system of claim 22 wherein the elongated supporting structure is made of two separate elongated members, each comprising a respective one of the supporting elements and an attachment section configured to connect to a lateral side of the elongated circuit board, the attachment sections of the elongated members being configured to form an elongated recess along the elongated support structure together with the circuit board being connected to them.

24. The system of claim 22 wherein the elongated support structure comprises an elongated reflector surface having a curved sectional shape and mounted therein facing the circuit board, said reflector surface configured to reflect a narrow beam of light emitted from the light emitting elements towards the wall of the tube.

25. The system of claim 22 or 23 wherein each supporting element is connected to the elongated circuit board via a slanted section of said member, the slanted or curved sections being configured to reflect the light from the light emitting elements towards the wall of the tube.

26. The system according to claim 25 wherein at least one of the slanted sections of the support element is curved or of parabolic shape.

27. The system of any one of claims 22 to 26 wherein the supporting elements are configured to position the elongated recess and the circuit board mounted in it at a predetermined distance from the wall of the tube.

28. The system of any one of claims 22 to 27 wherein the supporting elements are depressible elements operable for snugly fitting the elongated support structure inside the tube.

29. The system of any one of claims 23 to 28 wherein the elongated recess is adapted to reflect light emitted by the light emitting elements.

30. The system of any one of claims 22 to 29 wherein the elongated supporting structure comprises a heat conducting material serving as a heat sink.

31. The system of any one of claims 22 to 30 wherein the tube comprises two or more areas having different level of transparency configured to provide a certain illumination pattern therethrough.

32. The system of any one of claims 1 to 14 wherein the lighting system comprises:

a plurality of elongated panels, each one of said panels carrying an array of light emitting elements and one or more patterns of a soldering composition material deposited on said panel, said soldering material composition patterns being electrically connected to the light emitting elements;

a frame connectable to an electrical power source and comprising a plurality of pass through holes, each one of said pass through holes configured to provide electrical connection to said power source and fit and mate with one of said soldering material patterns deposited on one of the panels,

each one of said holes being configured to receive soldering material composition inside it and establish mechanical and electrical connection with one of said panels by combining the received soldering material composition with the soldering material pattern provided on said panel.

33. The system of claim 32 wherein the holes and the soldering material composition patterns are configured to align the panels carrying said patterns with respect to the frame.

34. The system of claim 32 or 33 comprising light dispersing elements optically 5 coupled to at least some of the light emitting elements.

35. The system of any one of claims 32 to 34 wherein the elongated panels are adapted to connect to the frame only at one end of the panels.

36. The system of any one of claims 32 to 35 wherein the elongated panels are adapted to connect to the frame at both ends of the panels.

10 37. A method of measuring ambient light intensity in a vicinity of a light source, the method comprising:

generating a sequence of light illumination stoppages of said light source, starting from a minimal illumination stoppage time, and gradually increasing illumination stoppage time of each consecutive illumination stoppage within said 15 sequence until reaching an adequate time duration;

measuring the ambient light intensity during at least said adequate time duration stoppage; and

following said adequate time duration stoppage, generating another sequence of illumination stoppages of said light source with gradually decreasing illumination 20 stoppage time of each consecutive illumination stoppage within said another sequence until substantially reaching said minimal illumination stoppage time.