LED LAMP FOR LIGHTING WITH RADIO CONTROL

It is disclosed a lamp for public, industrial or commercial lighting, with radio control. The lamp comprises a casing provided with an opening, a protection screen and a printed circuit board housed entirely inside the casing. The board comprises a printed circuit board comprising a mounting surface on which are mounted at least one light beam source, a processing unit, a transceiver of wireless signals connected to the processing unit, an antenna connected to the transceiver and a power supply circuit.

BACKGROUND

Technical Field

The present disclosure generally relates to the field of lamps for industrial, commercial and public illumination, for example road lighting.

More in particular, the present disclosure relates to a LED lamp equipped with radio control, which integrates, on a same board, the LEDs, the power supply system, the radio transceiver and the antenna.

Description of the Related Art

Smart lamps are known for lighting using LED technology, equipped with telecontrol systems.

Smart lamps of known type comprise a casing inside which the LEDs and the power supply circuit of the LEDs are positioned, so as to be protected by atmospheric agents.

Smart lamps further comprise a radio transceiver which allows the lamp to connect via radio with the other surrounding lamps and with a local or remote control centre: in this way it is possible to suitably vary the light intensity of the LEDs of the lamp in such a way as to optimise energy consumption and lighting needs in a determined area.

The radio transceiver can be mounted inside or outside the casing of the lamp.

The antenna is mounted on the outside of the body of the lamp, so as to guarantee a sufficient quality of the transmitted and received radio signal, but this creates the drawback that the antenna is exposed to atmospheric agents, with the risk that it will be damaged, thus reducing the working life of the whole lamp.

Further, the position of the antenna outside the body of the lamp worsens the aesthetic appearance of the lamp.

BRIEF SUMMARY

The present disclosure relates to a LED lamp for indoor or outdoor lighting as defined in the appended claims.

The Applicant has perceived that the LED lamp for lighting according to the present disclosure has the following advantages:it increases the reliability of the lamp (i.e. it increases the working life thereof);it reduces the number of components of the lamp and facilitates the mounting thereof during its production, thus reducing mounting errors;it avoids openings, fittings, seals or whatever else is necessary for the fixing of the antenna or the fitting of additional external modules (NEMA, ZHAGA etc.);it allows transmitting/receiving radio signals from any angular spatial direction on the horizontal plane;it is less expensive;it has a more attractive outer appearance.

One embodiment of the present disclosure relates to a lighting system as defined in the appended claims.

DETAILED DESCRIPTION

It should be observed that in the following description, identical or analogous blocks, components or modules are indicated in the figures with the same numerical references, even where they are illustrated in different embodiments of the disclosure.

With reference toFIG. 2, a block diagram of a lamp1for road lighting according to the disclosure is shown.

The above-described components are closed inside a casing of the lamp1.

With reference toFIG. 1, it shows a lamp1mounted on the upper end of a post fixed for example to the edge of a road surface or a pavement, in order to light the road surface and/or the pavement.

The casing of the lamp1comprises a metallic body1-1(for example aluminium) and further comprises an opening which allows the passage of the light beam generated by the LED string5and of the radio signal transmitted/received by the antenna10.

The casing of the lamp1further comprises a protection screen1-2at least partially transparent with respect to the light beam (for example made of a glass or plastic material), wherein said screen1-2is mounted in the opening in such a way as to occupy the whole surface defined by the opening: in this way the electronic components mounted inside the lamp1(in particular the LED string5) are protected from atmospheric agents and further the light beam generated by the LED string5is able to illuminate the surrounding environment in which the lamp1is mounted.

The antenna10is mounted on the printed circuit board20positioned inside the metallic body1-1of the housing so that the antenna10is electrically isolated from the metallic body of the casing of the lamp1and is positioned in proximity of the opening of the body of the casing itself (and therefore the antenna is positioned in proximity of the protection screen1-2), as shown inFIG. 2: in this way the electromagnetic wave generated/received by the antenna10is able to cross the protection screen1-2with a sufficient intensity to be received up to a distance of about 150/200 metres from the lamp on which the antenna10is mounted.

Advantageously, the antenna10is mounted on a portion of the protection screen1-2, in particular on a central portion of the protection screen1-2.

The term “LED string” is intended to mean a series connection of two or more light-emitting diodes, hereinafter indicated as LED (Light Emitting Diode).

In one embodiment, a LED string5can be divided into a plurality of segments, each segment comprising a series connection of a plurality of LEDs.

In other words, two or more LEDs connected in series can be grouped in such a way as to form a group of LEDs and thus a LED string can be composed of two or more groups of LEDs.

Moreover, one or more groups (or segments) of LEDs can be in turn composed of the parallel connection of two or more series of LEDs.

The rectifier3comprises two input terminals adapted to receive a positive VAC+ and a negative VAC− alternating voltage and comprises an output terminal adapted to generate a rectified alternating voltage VRTF, as a function of the positive VAC+ and negative VAC− alternating voltage.

For example, the alternating voltage has an effective value equal to 230 volts and the rectified alternating voltage VRTFis equal to 325 volts.

In one embodiment, the rectifier3is implemented with a full wave diode bridge.

The current regulator4(of the direct drive type) is electrically connected with the rectifier3and with the LED string5.

The current regulator4comprises an input terminal Ito adapted to receive the rectified alternating voltage VRTFand comprises four input terminals It1, It2, It3, I4electrically connected to four respective different portions of the LED string5

The current regulator4has the function of regulating the value of the total current Istrflowing across the LED string5.

Moreover, the current regulator4is configured to regulate the value of the total current Istrflowing across the LED string5, in order to suitably vary the light intensity of the LED string5, as a function of the value of a control signal S_ctrl.

In one embodiment, the current regulator4is an integrated circuit identified with the code ACS1404.

The LED string5comprises a first terminal connected to the rectified alternating voltage VRTFand comprises a second terminal connected to the current regulator4.

It should be observed that, more in general, it is possible to interpose further electronic components between the output of the rectifier3and the first terminal of the LED string5.

In particular, the LED string5comprises the series connection of four or more LEDs5-1,5-2,5-3,5-4, wherein:the anode of LED5-1is connected to the output terminal of the rectifier3and thus it is configured to receive the rectified alternating voltage VRTF;the cathode of LED5-1is connected to the anode of LED5-2and to the channel1of the current regulator4;the cathode of LED5-2is connected to the anode of the LED5-3and to the channel2of the current regulator4;the cathode of LED5-3is connected to the anode of the LED5-4and to the channel3of the current regulator4;the cathode of LED5-4is connected to the channel4of the current regulator4.

It can be observed that, more in general, each of the LEDs5-1,5-2,5-3,5-4can be a series connection of two or more LEDs, that is, each series connection is a segment of the LED string5.

The anti-flicker circuit8has the function of reducing any flicker of the light intensity generated by the LED string5.

The anti-flicker circuit8is implemented for example with the set of a bias stage8(typically a voltage divider with two resistors), an electronic switch6, a capacitor7, which are connected as shown inFIGS. 1-3of PCT application having publication number WO 2018/172980 A1.

The voltage converter6has the function of carrying out a voltage conversion from a first value to a second value smaller than the first value.

The voltage converter6thus comprises an input terminal adapted to receive the rectified alternating voltage VRTFand comprises an output terminal adapted to generate a low DC current V3.3.

For example, the voltage converter6carries out the conversion of the rectified alternating voltage VRTFhaving an effective value equal to 325 V into the low DC current V3.3 equal to 3.3 Volt.

The processing unit7has the function of suitably controlling the light intensity generated by the LED string5, in order to optimise the energy consumption of the lamp1and with the purpose of satisfying the lighting needs of a determined area.

The processing unit7is for example a microprocessor or a microcontroller running an appropriate software program.

Alternatively, the processing unit7is a programmable electronic device (for example an FPGA).

In particular, the processing unit7is electrically connected to the current regulator4and comprises an output terminal adapted to generate the control signal S_ctrl to appropriately vary the light intensity of the LED string5, by means of the control of the value of the current flowing across the LED string5.

The transceiver9is electrically connected on one side to the antenna10(for example by means of an electric cable11) and on the other side to the processing unit7(by means of an electric track on the printed circuit board20).

The transceiver9has the function of modulating/demodulating the signals to generate/receive a radio signal in the frequency band comprised between 400 Mhz and 2.4 Ghz, in order to receive, from outside, commands for controlling the operation of the lamp1(for example, commands for switching on or off the LED string5, commands for varying the intensity of the light beam generated by the LED string5) and in order to externally transmit the monitoring information of the operation of the lamp1(for example, alarm messages regarding the operation of the lamp1).

In particular, the transceiver9comprises a first input/output terminal adapted to receive the transmission/receiving signal S_rx_tx from the antenna10carrying the commands for controlling the operation of the lamp1and is adapted to transmit, towards the antenna10, the transmission/receiving signal S_rx_tx carrying the monitoring information of the operation of the lamp1.

The transceiver9further comprises a second input/output terminal adapted to receive the internal signal S_d from the processing unit7, the internal signal S_d carrying the monitoring information of the operation of the lamp1, and adapted to transmit to the processing unit7the internal signal S_d carrying the commands for controlling the operation of the lamp1.

The transceiver9is configured to demodulate the transmission/receiving signal S_rx_tx and to generate therefrom the internal signal S_d carrying said commands for controlling the operation of the lamp1; moreover, the transceiver9is configured to modulate the internal signal S_d and to generate therefrom the transmission/receiving signal S_rx_tx carrying the monitoring information of the operation of the lamp1.

The antenna10is electrically connected to the transceiver9and has the function in transmission of converting the generated electric signal of the transmission/receiving signal S_rx_tx into an electromagnetic wave which propagates outside of the lamp1, crossing the protection screen1-2.

Moreover, the antenna10has the function in reception of converting the electromagnetic wave received from outside the lamp1via a radio signal S_r (i.e. a wireless signal) into an electric signal of the transmission/receiving signal S_rx_tx.

Advantageously, the antenna10is implemented with a special shape, illustrated in greater detail in the following with reference toFIGS. 4A-4D, 4E, 4F, 4G-H.

Said special shape allows—possibly together with the surface20-1of the printed circuit board20on which the antenna10is mounted—obtaining a radiation diagram which is substantially circular in the three sections of the three planes (X, Z), (Y, Z), (Y, X) of the reference system (X, Y, Z) associated to the antenna10(seeFIGS. 5A-C), thus maximising the power of the electromagnetic waves received/transmitted from/towards the outside of the lamp1along the whole 360° angle about the antenna10: this allows connecting a lamp1via radio with various other surrounding and similar lamps positioned around it in any angular position.

With reference toFIG. 3, it shows a single printed circuit board20positioned inside the casing of the lamp1and on which the electronic components are mounted.

The board20is for example made of FR4 material.

FIG. 3shows that the board20comprises a mounting surface which is flat and on which are mounted the LEDs of the string5(for simplicity's sake indicated by one LED5-1only), the antenna10, the processing unit7, the transceiver9and the power system, wherein the processing unit7and the transceiver9are implemented with a single electronic component.

It can be observed that the board20comprises a metallic layer20-1(for example made of aluminium) which extends substantially over the whole flat surface of the board20and which defines a ground surface, i.e. a reference ground voltage (i.e. 0 volts).

Note that more generally it is sufficient for there to be present a flat portion of the mounting surface of the board20having the metallic layer, so that the antenna10is mounted inside said flat portion covered by the metallic layer.

The antenna10is electrically connected to the transceiver9by means of an electric connecting cable11composed of an internal conductor and an external conductor (for example a metallic braid), wherein the two conductors are electrically separated from each other by an insulating material.

A first end of the internal conductor of the cable11is electrically connected to a first input/output terminal of the transceiver9; a second end of the internal conductor of the cable11is electrically connected to the antenna10, in particular to an upper lamination10-2which will be illustrated in greater detail in the following.

Moreover, a first end of the external conductor is electrically connected to a ground terminal of the transceiver9; a second end of the external conductor is electrically connected to a ground reference of the antenna10, in particular to a lower lamination10-1which will be illustrated in greater detail in the following.

Alternatively, the antenna10is electrically connected to the transceiver9by means of a track (appropriately defined in length and shape) of the printed circuit board20.

It can be observed inFIG. 3that the antenna10is mounted in proximity of a pair of LEDs, so as to exploit the passage of the lamp1towards the outside allowed for the electromagnetic waves by the protection screen1-2.

More in general, a plurality of light emitting diodes is mounted on a portion of the mounting surface of the board located in correspondence of the opening of the body of the casing of the lamp1(and therefore in correspondence of the protection screen1-2) and in this case the antenna10is mounted in proximity of a perimeter portion of said portion of the surface comprising the plurality of LEDs.

FIGS. 4A-D,4E,4F,4G-H show in greater detail the antenna10mounted inside the casing of the lamp1and in proximity of the protection screen1-2.

It can be observed that the antenna10is formed by a lower lamination10-1and by an upper lamination10-2each having a flat surface, and are parallel to one another.

The flat surface of the upper lamination10-2is parallel to the flat surface20-1of the printed circuit board on which the electronic components are mounted.

The laminations10-1,10-2are separated from one another by a distance h which is a function of the frequency band at which the antenna10operates.

For example, the distance h is equal to 9 millimetres [mm] in a case where the antenna operates to transmit/receive a radio signal in the band comprised between 800 Mhz and 2.4 Ghz.

The upper lamination10-2is partly overlapped (in a top view of the antenna10) on the lower lamination10-1, as shown inFIG. 4F.

In fact, in transmission the lower lamination10-1has the function of concentrating the electromagnetic waves towards the upper lamination10-2, which is thus able to transmit power towards any angular direction in space, i.e. along an entire 360° angle of the sections of the radiation diagram of the antenna20, as illustrated inFIGS. 5A-C.

Viceversa, in reception the lower lamination10-1has a reflector function which concentrates the received electromagnetic waves towards the upper lamination10-2, which is thus able to receive power from any angular direction in space around the antenna10.

The laminations10-1,10-2are made of a metallic material and thus are sufficiently rigid.

The lower lamination10-1is fixed to the printed circuit board20(for example by means of a glue) and constitutes the ground reference of the antenna20.

The upper lamination10-2is the positive terminal of the antenna10and is such to carry out the transmission/reception of power towards/from the environment surrounding the lamp post on which the lamp1is mounted, by means of a radio signal S_r.

Moreover, the upper lamination10-2is electrically connected to the first input/output terminal of the transceiver9, in particular by means of the internal conductor of the electric cable11.

Advantageously, the metallic layer20-1of the printed circuit board contributes to realising (together with the lower lamination10-1) the reflection function of the received electromagnetic waves (from outside the lamp1by means of the radio signal S_r) towards the upper lamination10-2, in order to obtain a radiation diagram of the antenna20which transmits and receives power in all spatial directions.

In particular, the lower lamination10-1is a metallic sheet having a surface with a substantially rectangular shape and a thickness that is much smaller than the dimensions of the sides of the rectangular surface, but sufficient to obtain the lower lamination10-1with a good degree of rigidity.

For example, the longer side a of the rectangular surface of the lower lamination10-1is equal to 38.0 mm, while the shorter side b is equal to 13.0 mm and the thickness is equal to 0.3 mm.

Likewise, the upper lamination10-2is a metallic sheet having a surface with a substantially rectangular shape and a thickness that is much smaller than the dimensions of the sides of the rectangular surface, but sufficient to obtain the upper lamination10-2with a good degree of rigidity.

For example, the longer side c of the rectangular surface of the upper lamination10.2is equal to 13.8 mm, while the smaller sided is equal to 13.2 mm and the thickness is equal to 0.3 mm.

In one embodiment, the lower lamination10-1comprises two rectangular portions10-1a,10-1bside-by-side to each other along the respective shorter sides and respectively defined by sides having dimensions (a2, b) and (a1, b1) (seeFIGS. 4A and 4F), so that the upper lamination10-2is completely overlapped (in a top view) on the portion10-1aof the lower lamination (see the top view ofFIG. 4F) and so that the remaining non overlapping lower portion10-1ais positioned (in a top view) laterally to both sides d of the upper portion10-1, wherein a1+a2=a, b1is smaller than b, c is smaller than a2.

For example, the two rectangular portions have the following dimensions:a1=14.5 mm;a2=23.4 mm;b1=10.4 mm;b=13.0 mm;b=13.85 mm.

It is defined (seeFIGS. 4A and 4D) a Cartesian reference system (X, Y, Z) for antenna10in which the axes X, Y and Z are defined as follows:axis X is defined by the main extension direction (side a) of the lower lamination10-1;axis Z is defined by the secondary extension direction (side b) of the lower lamination10-1;axis Y is defined by the direction of the thickness of the lower lamination10-1, i.e. the perpendicular to the flat surface defined by the lower lamination10-1.

The plane (X, Y) corresponds to the opening in which the protection screen1-2of the lamp1is housed.

Therefore the lower lamination10-1has the main extension along the axis X and has the secondary extension along the axis Z.

Likewise, the upper lamination10-2thus has the main extension along axis X and has the secondary extension along axis Z, i.e. the main extension of the upper lamination10-2is parallel to the main extension of the lower lamination10-1and the secondary extension of the upper lamination10-2is parallel to the secondary extension of the lower lamination10-1.

The antenna10further comprises a support element10-3made of a metallic material having the function of supporting the upper lamination10-2with respect to the lower lamination10-1or with respect to the printed circuit board20.

In particular, the support element10-3mechanically connects the lower lamination10-1to the upper lamination10-2, by means of at least a part of a lower edge thereof.

The support element10-3has a substantially flat surface having a main extension direction which is parallel to the main extension direction of the lower lamination10-1(side a) and of the upper lamination10-2(side c) and has a secondary extension direction which is parallel to the secondary extension direction of the lower lamination10-1(side b) and of the upper lamination10-2(side d), so that the secondary extension direction of the support element10-3is perpendicular to the surface of the lower lamination10-1and of the upper lamination10-2.

The support element10-3has a lower edge a3(seeFIGS. 4A, 4D, 4E, 4G) which is connected to at least a part of an edge of the lower lamination10-1along the main extension direction thereof, in particular with a part of the edge of the portion10-1aalong the side a2.

Moreover, the support element10-3has at least one upper edge21(seeFIGS. 4A, 4B, 4C, 4D, 4E) which is connected to at least one edge of the upper lamination10-2along the main extension direction thereof.

More in particular, the support element10-3is also a metallic lamination that comprises four portions10-3a,10-3b,10-3c,10-3d(seeFIG. 4G) defined as follows:the portion10-3a(broken line towards the right inFIG. 4G) has a substantially rectangular shape having a main extension direction parallel to the main extension direction of the laminations10-1,10-2(thus the main extension direction of the portion10-3ais parallel to the axis X) and having a secondary extension direction that is perpendicular to the surface of the laminations10-1,10-2(thus the secondary extension direction of the portion10-3ais parallel to the axis Y);the portion10-3b(broken line towards the left inFIG. 4G) has an L shape having a main extension direction parallel to the main extension direction of the laminations10-1,10-2(thus the main extension direction of the portion10-3ais parallel to the axis X) and having a secondary extension direction that is perpendicular to the surface of the laminations10-1,10-2(thus the secondary extension direction of the portion10-3bis parallel to the axis Y);the portion10-3c(dotted line with a greater density inFIG. 4G) has a substantially rectangular shape having a main extension direction that is perpendicular to the surface of the laminations10-1,10-2(thus the main extension direction of the portion10-3cis parallel to the axis Y) and having a secondary extension direction that is parallel to the main extension direction of the laminations10-1,10-2(thus the secondary extension direction of the portion10-3cis parallel to the axis Y);the portion10-3d(dotted line with a lesser density inFIG. 4G) has a substantially rectangular shape having a main extension direction that is perpendicular to the surface of the laminations10-1,10-2(thus the main extension direction of the portion10-3dis parallel to the axis Y) and having a secondary extension direction that is parallel to the main extension direction of the laminations10-1,10-2(thus the secondary extension direction of the portion10-3dis parallel to the axis X).

The portions10-3c,10-3dare interposed between the portions10-3aand10-3b.

The lower longer side of the substantially rectangular shape of the portion10-3acomprises a part that defines the lower edge a3which is connected to a part of the edge of the lower lamination10-1and comprises a remaining part that is not connected to the lower lamination.

The upper longer side of the substantially rectangular shape of the portion10-3acomprises a first part connected to the lower shorter side of the portion10-3c,comprises a second part connected to the lower shorter side of the portion10-3d,comprises a third part connected to the lower shorter side of the portion10-3cand comprises a remaining fourth part that is not connected either to the portions10-3c,10-3d,10-3bor to the upper lamination10-2.

The upper shorter side of the portion10-3cis connected to a part of the longer side c of the upper lamination10-2and the upper shorter side of the portion10-3dis connected to another part of the same longer side c of the upper lamination10-2.

The portion10-3bcomprises an edge connected to a part of the left longer side of the portion10-3b,while the remaining edges of the portion10-3bare not connected.

The dimensions of the shorter side of the rectangular shape of the portion10-3dare slightly smaller than the dimensions of the shorter side of the rectangular shape of the portion10-3c.

For example, the shorter side of the portion10-3cis equal to 2.6 mm and the shorter side of the portion10-3dis equal to 2.1 mm.

The distance a4between the adjacent longer sides of the portions10-3cand10-3dis for example equal to 2 mm.

In case wherein the antenna10is electrically connected to the transceiver9by means of an electric cable11composed of the internal conductor and of the external conductor (for example a metal braid), the portion10-3aof the lamination10-3is electrically connected to an end of the internal conductor, thus carrying out the electrical connection of the upper lamination10-2of the antenna10to the input/output terminal of the transceiver9via the portion10-3a

The antenna10further comprises a connecting lamination10-4having a rectangular shape (for example, sides having dimensions of 3 mm and 4.0 mm), which is connected to the end of the lower lamination10-1, in particular with a part of the longer side of the portion10-1a.

In particular, the connecting lamination10-4has the longer side parallel to the longer side a of the lower lamination10-1(and thus it is parallel to the direction of axis X) and has the shorter side perpendicular to the surface of the laminations10-1,10-2(and thus it is parallel to the direction of axis Y).

In case wherein the antenna10is electrically connected to the transceiver9by means of an electric cable11composed of an internal conductor and an external conductor (for example a metal braid), the connecting lamination10-4is electrically connected to an end of the external conductor (for example the metal braid) and thus to the ground reference of the antenna10, thus carrying out the electrical connection of the lower lamination10-1to the ground reference via the connecting lamination10-4.

Note that the presence of the lower lamination10-1is not essential for the purposes of the operation of the antenna10, i.e. it is possible that only the upper lamination10-2is fixed directly to the metallic layer20-1of the board20by means of the support element10-3: in this case the upper lamination10-2is fixed (by means of the support element10-3) to the metallic layer20-1of the board20by welding or by other fixing means and the reflection function is implemented with the portion of the metallic layer20-1of the board20which is positioned in proximity of the upper lamination10-2surrounding it.

With reference toFIGS. 5A, 5B, 5C, they show using a continuous line three sections of the radiation diagram of the antenna10, respectively in the three planes (Z, X), (Z, Y), (X, Y) of the space (X, Y, Z), wherein the axes X, Y, Z are orientated as illustrated previously inFIGS. 4A, 4D, 4G, 4H.

In particular, the three sections of the radiation diagram show the gain value (measured in dBi) of the antenna10as the angular direction (measured in degrees) changes in the three planes (Z, X), (Z, Y), (X, Y).

It can be observed that the three radiation diagrams have a substantially circular shape, i.e. the gain of the antenna in each of the three planes is substantially constant as the whole 360° angle changes: therefore the radiation diagram of the antenna10in the space (X, Y, Z) has a shape alike to a sphere, i.e. the antenna10can transmit/receive power in/from all directions of the space.

Therefore the antenna10is able to transmit/receive power towards/from any angular direction in the surrounding space: this allows connecting a lamp post1via radio with various other surrounding lamp posts positioned around it in any angular position.

The antenna10has an average gain equal to about 4.2 dBi when using a board20made of FR4 material and equal to 4.7 dBi when using a board20with an aluminium substrate, even when varying the angle in the plane (X, Y) which corresponds to the opening in which the protection screen1-2of the lamp1is housed.

Note that the disclosure is not limited to a lamp for public lighting (typically roads), but it can also be used for private lighting in commercial, office and industrial environments.

Note also that the disclosure is not limited to a lamp with LED technology in order to generate the light beam, but other technologies for generating the light beam can also be used.