Furniture piece with lighting system

The present patent application for industrial invention relates to a furniture piece with lighting system.

Furniture pieces, such as shelves or showcases that need to be lit are known on the market. For this reason, these types of furniture pieces are provided with lighting devices, such as LEDs.

Generally speaking, a furniture piece comprises fixed parts, such as the frame of the furniture piece, and mobile parts, such as shelves, drawers, door panels and the like. The mobile parts are slidingly or revolvingly mounted to the fixed parts.

The lighting of the mobile parts of the furniture piece is currently obtained with extensible electrical wirings that connect a power supply to the lighting devices disposed in the mobile parts. Said extensible wirings are not very versatile and not very functional, especially when the mobile parts of the furniture piece are to be moved.

In order to avoid using the extensible wirings, connectors with electromechanical contacts are known, being disposed in the fixed part and in the mobile parts of the furniture piece to connect the cables coming from the power supply with the cables connected to the lighting devices disposed on the mobile parts. Said connectors provide for a magnetic, optic or electric switch that is activated when the mobile part is mounted in the fixed part to allow the current to pass from the cables of the power supply to the cables of the lighting devices.

The magnetic switches generally provide for a reed sensor disposed in the fixed part that is activated by a magnet disposed in the mobile part. The optical switches provide for an optical detector disposed in the fixed part in such a way to detect the mobile part. The electrical switches provide for electrical contacts disposed in the fixed part and in the mobile part. In any case, electricity must be brought from the fixed part to all points of the mobile parts where lighting devices are provided, requiring the intervention of specialized technicians every time the position of the mobile part is changed.

Such an electrical distribution becomes complicated especially when flexibility is required in the composition of the furniture piece that can be personalized and modified by the customer with different layouts of the mobile part. A classical example is represented bookshelves with multiple shelves that are placed in different positions according to the specific time and to the size of the products to be supported. In such a case, the electrical parts may give conduction problems caused by oxidation. Moreover, the unused electrical parts would leave some visible slots, contacts, wires, etc., with an unpleasant aesthetic effect.

Furthermore, if the electrical cables of the power supply are connected directly to the mains, electrical safety problems may be created in the fixed part of the furniture piece even if the structure is earthed correctly.

It must be considered that an electrical system connected to the mains takes energy also in idle conditions (for example television sets) and as a matter of fact many countries have approved laws to limit such consumption to very low values.

According to the prior art, a power supply connected to the electrical mains is used in the fixed part of the furniture piece. It must be considered that, being provided with electrical transformers that are mutually coupled, such a power supply dissipates power taken from the mains also in absence of load, that is to say when the lighting devices are not in operation. Consequently, a useless consumption of electricity is generated.

The purpose of the present invention is to eliminate the drawbacks of the prior art by providing a furniture piece with lighting system that is versatile, functional and modular. Another purpose of the present invention is to provide such a furniture piece with lighting system that is simple to make and install.

Another purpose of the present invention is to provide such a furniture piece with lighting system that is reliable and suitable for avoiding useless energy consumption.

These purposes are achieved according to the invention with the characteristics of the independent claim 1 .

Advantageous embodiments will appear from the dependent claims.

The furniture piece of the invention comprises:

- a fixed part intended to be fixed to the ground or to the wall,

- at least one mobile part intended to be removably mounted to the fixed part,

- a light source mounted on the mobile part to illuminate the furniture piece,

- a power supply,

- a transmitter disposed in the fixed part and electrically connected to the power supply, and

- a receiver disposed in the mobile part and electrically connected to the light source.

The transmitter comprises at least one transmission head comprising a primary winding. The receiver comprises a reception head comprising a secondary winding.

The primary winding and the secondary winding are disposed in the fixed part and in the mobile part, respectively, in such a way that, when the mobile part is mounted in the fixed part, the primary winding of the transmission head is coupled with the secondary winding of the reception head, forming a transformer with mutual inductance that transfers electricity from the power supply to the light source.

According to the present invention, by transferring electricity by means of electromagnetic force lines, and not by contact, it is possible to make the electrical system completely invisible, inserting the electronic parts inside the furniture piece and covering them with a veneer sheet, paint, belts, etc.

In a set of shelves, each mobile part (shelf) is provided with the energy receiver (reception head) and the lighting part that are connected in an invisible way. In this way the shelves have a very high internal protection (IP) degree and can be stocked in the warehouse for years, being used only when necessary.

In the fixed part of the furniture piece, the transmission heads are placed in predefined positions, are protected in the same way as in the shelves and are perfectly invisible.

No risks of accidental contacts with electrical discharges towards the ground exist for the user because the electrical system is insulated from the mains and energy is transferred like in an ordinary transformer, with the primary winding in the fixed part and the secondary winding in the mobile part. Moreover, the electrical system can operate at low voltage, with maximum voltage of 48 Vrms. Also the electrical part of the fixed parts can use low voltage of 48Vrms, thus reducing all problems of electrical safety.

The furniture piece of the present invention can also operate at mains frequency with the primary winding and the relevant core disposed on the fixed part of the furniture piece and the secondary winding and the relevant core disposed in the mobile part of the furniture piece.

In order to increase the efficiency of the energy transfer from the transmitter to the receiver, such an energy transfer is not made at mains frequency, but at frequencies higher than the audible frequencies, that is to say ultrasonic frequencies higher than 20,000 Hz. Advantageously, a sinusoidal waveform is used to minimize electromagnetic pollution. The use of ultrasonic frequencies permits to miniaturize the transmitter and receiver devices, thus providing technicians and designers with higher versatility when designing the furniture piece.

In all cases, galvanic insulation exists between the primary winding of the transmitter and the secondary winding of the receiver even at distances of few millimeters requested by the manufacturers to remedy production tolerances. Moreover, galvanic insulation is also used to obtain a current limitation on the secondary winding in case of malfunctioning of the light source. In fact, in such a case, a dispersion inductance is generated, which is translated in virtual limiting impedance. The farther the secondary winding of the receiver from the primary winding of the transmitter, the higher the virtual impedance will be, allowing for dimming the luminous flux emitted in the light source, without the need of using sophisticated and expensive dimmers.

The luminous flux can be also dimmed by acting on the frequency of the primary winding or also by acting on the number of turns of both the primary winding and the secondary winding. By simply regulating the number of turns of the primary winding and of the secondary winding, the luminous flux can be differentiated shelf by shelf, thus increasing the system flexibility.

Moreover, it must be considered that the primary winding of the transmitter is connected to the mains, and the mains delivers electricity to the primary winding only in presence of a load, that is to say only when the secondary winding is proximal to the primary winding.

Additional features of the invention will appear clear from the detailed description below, which refers to merely illustrative, not limiting embodiments, wherein:

Fig. 1 is a diagrammatic perspective view of a furniture piece with lighting system according to the invention;

Fig. 2 is a diagrammatic top view of the furniture piece of Fig. 1 ;

Fig. 3 is a diagrammatic electrical circuit of the lighting system of the furniture piece according to the invention;

Fig. 4 shows four electrical diagrams of four possible transmission heads;

Fig. 5 shows four electrical diagrams of four possible reception heads; Fig. 6 is an electrical diagram that shows the sinusoidal oscillator of the transmitter of Fig. 3 in detail;

Fig. 7 is an electrical diagram that shows the timer and the current sensor of the transmitter of Fig. 3 in detail;

Fig. 8 is an electrical diagram of a first embodiment of the receiver of Fig. 3; and

Fig. 9 is an electrical diagram of a second embodiment of the receiver of Fig. 3.

With reference to Figs. 1 and 2, the furniture piece according to the invention is disclosed, being generally indicated with reference numeral 100.

The furniture piece (100) comprises a fixed part (1 ) and at least one mobile part (2) removably mounted to the fixed part (1 ).

For example, the fixed part (1 ) can be a frame intended to rest on the ground or be fixed to a wall.

The mobile parts (2) can be shelves of a set of shelves, drawers of a chest of drawers, translating or rotating door panels and the like.

The furniture piece (100) comprises a lighting system (101 ). The lighting system (101 ) comprises:

- a light source (3) disposed in the mobile part (2) of the furniture piece,

- a power supply (4) intended to be connected to the electrical mains,

- a transmitter (5) fixed to the fixed part (1 ) of the furniture piece and electrically connected to the power supply (4), and

- a receiver (6) fixed to the mobile part (2) of the furniture piece and electrically connected to the light source (3).

Advantageously, the light source (3) comprises a LED strip connected by means of wiring (60) to the receiver (6).

The transmitter (5) comprises an electronic circuit (50) connected by means of electrical wiring (51 ) to a plurality of transmission heads (52) 0152

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disposed in the fixed part (1 ) of the furniture piece in positions where the mobile parts (2) of the furniture piece are to be mounted.

Advantageously, the transmission heads (52) are recessed in the fixed part (1 ) of the furniture piece. The transmission heads (52) are covered with a covering layer (10) applied on the fixed part of the furniture piece, in such a way not to be visible. The covering layer (10) can be a veneer sheet or a film.

Advantageously, the receiver (6) is recessed in the mobile part (2) of the furniture piece and is covered with a covering layer (20) applied on- the mobile part of the furniture piece, in such a way not to be visible. The covering layer (20) can be a veneer sheet or a film.

Only the light source (3) remains visible on each mobile part (2) because the receiver (6) and the wirings (60) are disposed inside the mobile part and are covered by the covering layer (20).

The transmission heads (52) are positioned in the fixed part (1 ) of the furniture piece in the positions where the mobile parts (2) are to be mounted. Also in this case, the wiring (51 ) and the transmission heads

(52) can be made invisible with the covering layer (10) of the fixed part.

The transmission heads (52) detect the presence of the receivers (6) and provide energy to the receivers (6), switching on the light sources

(3) of the mobile parts.

The transmission heads (52) are activated for few milliseconds every second. If no energy is taken by the receivers (6), the transmission heads (52) are in idle state. Instead, if energy is taken by the receivers (6), the transmission heads (52) remain active, providing energy to the light sources (3).

The removal of the mobile part (2) restores the idle condition of the transmission head (52) which was coupled to the receiver (6) of the removed mobile part, in such a way to comply with the energy saving rules.

With reference to Fig. 3, each transmission head (52) comprises a primary winding (Lp). The electronic circuit (50) of the transmitter comprises a signal generator (G) connected to the power supply (4) and to the transmission heads (52). The signal generator (G) is intended to generate a periodic signal to check the primary winding (Lp) of the transmission heads (52).

For example, the signal generator (G) comprises a sinusoidal oscillator (53) intended to generate a current signal of sinusoidal type. The signal generator (G) can also provide another type of periodic signal, such as a square wave.

A timer (54) is connected to the signal generator (G) in such a way to activate the signal generator for an activation time (τ) every preset time interval (T). Advantageously, the timer (54) has a duty cycle (d = τ/Τ) lower than 1/80, preferably the duty cycle of the timer is 1/100. For example, the activation time (τ) can be 10 ms and the time interval (T) can be 1000 ms. The timer (54) can be obtained by means of an astable vibrator.

A current sensor (55) is connected to the signal generator (G) and to the timer (54). The current sensor (55) is suitable for detecting the current that circulates in the signal generator (G).

During the activation period (τ), the sinusoidal oscillator (53) oscillates sinusoidally and the current sensor (55) detects the current absorbed at the sinusoidal oscillator (53), which is indicative of the current absorbed by the transmission heads (52) connected to the sinusoidal oscillator (53).

The load of the transmitter (5) is composed of the receivers (6) coupled with the relevant transmission heads (52). A minimum threshold value of current absorbed by a transmission head (52) when it is coupled to a receiver (6) is set.

The current sensor (55) is configured in such a way that, when the current sensor (55) detects a current absorbed by the transmission heads higher than the minimum threshold value, the current sensor (55) controls the timer (54) that is set in continuous operation, activating the sinusoidal oscillator (53) in continuous mode. As soon as the load is disconnected from the transmission heads (52), the current sensor (55) detects a current absorbed by the transmission heads lower than the minimum threshold value. Therefore the current sensor (55) controls the timer (54) that returns to the initial condition.

During the active phase of the sinusoidal oscillator (53), the transmission heads (52) can transmit energy only to the receivers (6) by switching on the relevant light sources (3).

The sinusoidal oscillator (53) is connected to the power supply (4). Advantageously, the power supply (4) comprises an electrical system intended to convert the voltage in mains alternate current into a direct current voltage of 24 Vdc, which is insulated from the mains and more suitable for powering the electronic components used. In this way, the transmitter (5) operates at low voltage, guaranteeing higher safety for the users.

The receiver (6) comprises a reception head (60) comprising a secondary winding (Ls). An electric circuit (61 ) connects the reception head (60) to the light source (3).

The primary winding (Lp) of the transmission head is intended to be coupled with the secondary winding (Ls) of the reception head, obtaining a transformer with mutual inductance that transfers electrical energy from the transmitter (5) to the receiver (6).

With reference to Fig. 4, in its simplest form (Fig. 4 (a)) the transmission head (52) comprises a simple primary winding (Lp). The winding (Lp) of the transmission head interacts with the sinusoidal oscillator (53), resonating at a set frequency (higher than 20,000 Hz) and creating magnetic force lines that, when coupled with the secondary winding (Ls) of the reception head (60), provide energy to the load composed by the light source (3) without a physical contact between the two heads. With reference to Fig. 4 (b), the transmission head (52) can comprise a winding (Lp) in parallel to a capacitor (C) in such a way to form a parallel resonator.

With reference to Fig. 4 (c), the transmission head (52) can comprise a core (N) disposed in a winding (Lp).

With reference to Fig. 4 (d), the transmission head (52) can comprise the core (N) disposed in a winding (Lp) in parallel to a capacitor (C).

With reference to Fig. 5, the reception head (60) is substantially similar to the transmission head (52).

With reference to Fig. 5 (a), the reception head (60) can comprise a simple secondary winding (Ls).

With reference to Fig. 5 (b), the reception head (60) can comprise a winding (Lp) in parallel to a capacitor (C) in such a way to form a parallel resonator.

With reference to Fig. 5 (c), the reception head (60) can comprise a core (N) disposed in a winding (Lp).

With reference to Fig. 5 (d), the reception head (60) can comprise a core (N) disposed in a winding (Lp) in parallel to a capacitor (C).

With reference to Fig. 6, the sinusoidal oscillator (53) comprises two MOSFETs (QA, QB) connected in a common source configuration.

The MOSFETs (QA, QB) are powered by means of an inductor (L1 ) connected to the power supply (4). A stabilization capacity (C22) is disposed at the output of the power supply (4) in order to be charged with the input voltage (Vc) coming from the power supply.

The inductor (L1 ) acts as current limiter. The inductor (L1 ) is connected to the transmission head (52). The transmission head (52) comprises a primary winding (Lp) with a central voltage tap in such a way to generate two inductors (L2, L3) connected in series and respectively connected to the drains of the two MOSFETs (QA, QB). The two inductors (L2, L3) are the primary winding (Lp) of a transformer and are part of a transmission head (52). For saving purposes multiple transmission heads (52) controlled by a single sinusoidal oscillator (53) can be used.

The transmission head (52) comprises a resonance circuit (56) disposed in parallel to the two inductors (L2, L3). The resonance circuit (56) comprises four capacities (C1 , C2, C3, C4) disposed in parallel. The capacities (C1 , C2, C3, C4) of the resonance circuit are optional and are in number of four in order to use SMD components. In fact, the current that crosses the resonance circuit (56) may be very high and should be divided in multiple capacities. In this way, the two inductors (L2, L3) can oscillate together with the resonance circuit (56) at a predefined resonance frequency. Fig. 6 shows only one transmission head (52), but the resonance frequency can change by adding other transmission heads (52).

Advantageously, the resonance circuit (56) is selected in such a way to obtain a resonance frequency higher than 20,000 Hz to avoid audible noise during operation.

The first MOSFET (QA) is controlled by two controlling resistances (R3, R1 ) connected to the gate of the MOSFET (QA). Also a Zener diode (D2) is connected to the gate of the first MOSFET (QA).

The second MOSFET (QB) is controlled by two controlling resistances (R4, R2) connected to the gate of the MOSFET (QB). Also a Zener diode (D4) is connected to the gate of the second MOSFET (Q5).

A first decoupling diode (D1 ) is disposed between the gate of the first MOSFET (QA) and the resonance circuit (56). A second decoupling diode (D3) is disposed between the gate of the second MOSFET (QB) and the resonance circuit (56). The decoupling diodes (D1 and D3) make the MOSFETs (QA, QB) conductive one at a time.

A monitoring resistor (R16) is connected to the sources of the two MOSFETs (QA, QB) and to the earth. The monitoring resistor (R16) permits to monitor the current absorbed by the sinusoidal oscillator (53) by means of the current sensor (55) as explained in detail with reference to Fig. 7. At the sources of the two MOSFETs (QA, QB) there is a SENSE pin of the circuit of Fig. 6 connected to the SENSE pin of the circuit of Fig. 7.

With reference to Fig. 7, the current sensor (55) comprises a comparator (U1 ) composed of an operational amplifier. A first input of the comparator (U1 ) is connected to the SENSE pin by means of a resistance (R17). A capacity (C9) is disposed between the first input of the comparator (U1 ) and the earth.

A second input of the comparator (U1 ) is connected to a trimmer resistance (R5) by means of a resistive divider comprising three resistances (R26, R15, R13), wherein the resistance (R26) is disposed between the second input of the comparator (U1 ) and the earth, the resistance (R15) is disposed between the second input of the comparator (U1 ) and the power supply voltage and the resistance (R13) is connected to the trimming resistance (R5). A capacity (C8) is disposed between the second input of the comparator (U1 ) and the earth.

The astable circuit of the timer (54) forces the sinusoidal oscillator (53) to oscillate for few milliseconds. The monitoring resistor (R16) is crossed by an electrical current that is proportional to the load, that is to say proportional to the current dissipated by the transmission head (52).

The second input of the comparator (U1 ) of the current sensor is positioned by means of the resistive divider obtained from the three resistances (R15, R26, R13) and the trimmer resistance (R5). When the average voltage value in the SENSE pin, detected in the first input of the comparator (U1 ) by means of the resistance (R17) exceeds the voltage established in the second input of the comparator (U1 ), the output of the comparator (U1 ) closes, short circuiting the capacity (C6) at the output of the comparator (U1 ) of the current sensor. As a result, the output of the comparator (U2) of the timer is forced to remain high, activating the CONTROL pin. The gates of the MOSFETs (QA, QB) of the sinusoidal oscillator are controlled by means of the transistors (Q3, Q4) (Fig. 6), maintaining the sinusoidal oscillator in operation, if the average voltage value in the first input of the comparator (U1 ) of the current sensor has a lower value than the average voltage value of the second input of the comparator (U1 ), the sinusoidal oscillator (53) is switched off, and the timer (54) repeats the cycle after approximately one second.

Going back to Fig. 6, the activation of the sinusoidal oscillator (53) is subordinated to a control that arrives at the gates of the MOSFETs

(QA, QB) from the timer (54) and also to the voltage at the drains of the two MOSFETs (QA, QB). To that end, a first control circuit (57) and a second control circuit (58) are provided (Fig. 7)

The first control circuit (57) is disposed between a pin (CONTROL) intended to be connected to the timer and the two MOSFETs (QA, QB).

The first control circuit (57) comprises two BJTS (Q4, Q3).

The first BJT (Q4) is a transistor of pnp type with base and collector in common by means of a resistance (R52). The emitter of the first BJT (Q4) is connected to the gate of the first MOSFET (QA) by means of the controlling resistance (R1 ) of the first MOSFET (QA). The emitter of the first BJT (Q4) is connected to the Vc voltage supplied by the power supply.

When the first BJT (Q4) is closed, it enables to activate the oscillator (53), controlling the gate of the first MOSFET (QA) by means of the controlling resistors (R1 , R3,) or the gate of the second MOSFET

(QB) by means of the controlling resistors (R2, R4).

The second BJT (Q3) is of npn type. The second BJT (Q3) has the base connected to the CONTROL pin, the emitter connected to the earth and the collector connected to the base of the first BJT (Q4) through the resistance (R53). A resistance (R6) is disposed between the base of the second transistor (Q3) and the earth. The CONTROL pin of Fig. 6 is connected to the CONTROL pin of Fig. 7.

With reference to Fig. 7, the CONTROL pin is connected to the timer (54) by means of a resistance (R14).

The timer (54) is an astable vibrator that comprises an operational amplifier (U2), a retraction circuit comprising a resistance (R1 1 ) in series to a diode (D5) and in parallel a second resistance (R10) and a controlling circuit composed of a resistive divider with three resistances (R19, R9, R7).

Going back to Fig. 6, the drains of the two MOSFETs (QA, QB) are connected to a pin (A) connected to the pin (A) of Fig. 7 by means of corresponding diodes (D10, D1 1 ) and a resistance (R95).

With reference to Fig. 7, the pin (A) of Fig. 7 is connected to the second control circuit (58) that comprises the BJT (Q2) with the base connected to the terminal (A). The transistor (Q2) of the second control circuit is in common base and collector configuration by means of a diode (D6).

The emitter of the BJT (Q2) of the second control circuit is connected by means of a resistance (R12) to the output of the operational amplifier (U2) of the timer.

Such a configuration of the first control circuit (57) and of the second control circuit (58) prevents the sinusoidal oscillator (53) from having both MOSFETs (Q1 , Q2) in conduction at the start-up, with devastating results.

In fact, the activation signal of the timer (54) can be sent towards the sinusoidal oscillator (53) only when at least one of the two MOSFETs (QA, QB) is not in conduction.

The sinusoidal oscillator composed of the two MOSFETs (QA, QB) must be controlled in order to oscillate; therefore, a suitable voltage must be present on the gates of the two MOSFETs (QA, QB). When the sinusoidal oscillator is powered, in the first instant, both MOSFETs (QA, QB) are open with both drains at 24V. If the sinusoidal oscillator (53) is normally started, alternately at the established frequency, the drains of the MOSFETs (QA, QB) will enter in conduction.

If both drains of the MOSFETs (QA, QB) are simultaneously in conduction, at least one MOSFET will break because of excessive current on at least one MOSFET. This will never happen because the controlling voltage that activates the gates of the MOSFETs (QA, QB) depends on the voltage at the drains of the MOSFETs (QA, QB). T IT2016/000152

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Therefore, in order for a MOSFET to operate, the other MOSFET must be very high (not in conduction).

Fig. 8 shows a first embodiment of the receiver (6). The reception head (60) comprises a secondary winding (Ls) with a central voltage tap that divides the secondary winding in two windings (Ls', Ls"). For example, the two windings (Ls', Ls") can have 32 turns each.

The electric circuit (61 ) connected to the reception head (60) comprises a rectifier (62). The rectifier (62) can comprise two diodes in parallel.

A resonance circuit (61 ) comprising three capacities in parallel

(C10, C12, C1 1 ) is disposed in parallel to the secondary winding (Ls) of the head. The three capacities (C10, C12, C1 1 ) are optional and are in number of three to divide the current crossing said capacities, in such a way to avoid high current and use SMD components. A load capacity (C5) is disposed at the output of the rectifier (62).

Fig. 9 shows a second embodiment of the receiver (6) wherein the secondary winding (Ls) of the reception head is a winding without central voltage tap, for example a winding with 32 turns.

In such a case the rectifier (62) is a diode bridge rectifier that comprises four diodes (D7, D13, D14, D12).

Numerous variations and modifications can be made to the present embodiments of the invention, which are within the reach of an expert of the field, falling in any case within the scope of the invention as disclosed by the attached claims.