DEVICE FOR LIGHT TRANSMISSION OF AN ANALOGUE SIGNAL

Description

Previous art

[0001] As is known, document US20160218807 describes a communication system comprising a light source to generate light; broadband light emitter control electronics to modulate a light signal and provide a broadband optical data transmission network using the light source; broadband light receiver control electronics to demodulate a light signal received from the broadband optical data transmission network; and a wired network transceiver coupled to the light emitter / receiver to receive and transmit data between the optical data transmission network and a wired circuit.

[0002] However, these solutions do not provide complete satisfaction.

[0003] Indeed, the communication system described in document US20160218807, by its very nature, requires transmitter control electronics with high computing power, as well as similar receiver control electronics. Such control electronics result in high energy consumption.

[0004] Furthermore, document US10341017 describes an optical audio signal transmission system by modulation of the light intensity emitted by a light source, and comprising a photodiode coupled to a demodulator.

[0005] The present invention aims to resolve all or part of the drawbacks mentioned above.

[0006] The present invention also aims to provide an alternative to the communication system described in document US20160218807. Description of the invention

[0007] To this end, the present invention relates to a light transmission device for transmitting an analog signal in a first frequency band below 20 kHz comprising: a transmission unit configured to transmit a light signal in the visible spectrum; an excitation unit configured to generate an excitation, the excitation being configured to excite the transmission unit; and wherein the frequency or duration of the excitation is determined as a function of a value of the analog signal, the excitation frequency being within a second frequency band greater than 1 MHz.

[0008] According to the invention, the excitation unit is configured to excite the transmission unit when said transmission unit is in a transient down regime or in a steady regime in which the light intensity is zero.

[0009] Such an arrangement, and more specifically an excitation frequency within a second frequency band above 1 MHz, ensures illumination acceptable to the human eye. For the purposes of this invention, the term "acceptable to the human eye" means having a frequency high enough that the human eye cannot perceive any flickering.

[0010] In one embodiment, the excitation frequency is 2 MHz. This excitation frequency allows for a higher quality analog signal without requiring a high-performance excitation unit and thus consuming more energy. Indeed, the higher the excitation frequency, the more precisely the emitted light signal varies.

[0011] Such an arrangement allows the transmission of a light signal with a variable intensity and thus allows the transmission of an analog light signal.

[0012] For the purposes of the present invention, the visible spectrum includes electromagnetic waves having a wavelength between 380nm and 780nm.

[0013] In one embodiment, such an arrangement allows the use of an existing transmission unit, for example, in a lighting network. This arrangement is therefore environmentally efficient.

[0014] Such an arrangement makes it possible to obtain the transmission of an analog signal by light without requiring a guide such as an optical fiber for example.

[0015] In one embodiment, the transmission unit comprises a phosphorescent light-emitting diode. In a preferred embodiment, the phosphorescent light-emitting diode is a white phosphorescent light-emitting diode.

[0016] Such an arrangement makes it possible to obtain a transmission unit capable of emitting light between two excitations for a longer time than an incandescent bulb, for example.

[0017] According to the present invention, the excitation unit is configured to excite the transmission unit when said transmission unit is in a transient down regime or in a steady regime in which the light intensity is zero.

[0018] For the purposes of the present invention, a falling transient regime is a transient regime in which the intensity of the light emitted by the emitting unit is decreasing. Such a transient regime is obtained between two excitations.

[0019] According to one embodiment, the light transmission device includes a first communication unit configured to communicate with a second remote communication unit according to an electromagnetic communication protocol.

[0020] For the purposes of the present invention, an electromagnetic signal is a radio signal.

[0021] Such an arrangement allows the transmission device to transmit data using an analog light signal but also to receive data using an electromagnetic signal.

[0022] According to one embodiment, the first communication unit is configured to communicate according to any of the electromagnetic communication protocols such as "RFID", "Bluetooth" or "BLE" for example.

[0023] The invention also relates to a light receiving device configured to generate an analog output signal comprising: a receiving unit with a latency of less than 1µs configured to receive a light signal emitted by a light transmission unit; an intensity measurement unit configured to measure the intensity of the light signal received by the receiving unit and to generate an analog output signal in a first frequency band below 20 kHz.

[0024] According to the invention, the light signal is generated by exciting the transmission unit when the intensity of the light emitted by the transmission unit is zero or decreasing, the receiving unit comprising a photovoltaic cell.

[0025] Such an arrangement makes it possible to obtain an analog signal transmitted by light.

[0026] A receiving unit with a latency of less than 1µs can receive a light signal emitted by a transmitting unit excited by an excitation unit at a frequency greater than 1MHz.

[0027] Such an arrangement, and more specifically the phosphorescent nature of the diode coupled with the latency of the photovoltaic cell, allows for smoothing of the analog signal generated at the output, without requiring demodulation.

[0028] According to one embodiment, such an arrangement makes it possible to obtain an energetically passive receiving unit, or even one that generates energy.

[0029] According to one embodiment, the photovoltaic cell is an organic photovoltaic cell known as OPV.

[0030] According to one embodiment, such an arrangement makes it possible to obtain a high reception gain and thus achieve good reception quality even when the intensity of the received light signal is much lower than the intensity of the ambient light. For example, the device according to the invention is capable of receiving a 40 LUX signal in an ambient light of more than 10,000 LUX.

[0031] According to one embodiment, the receiving device includes a second communication unit configured to communicate with a first remote communication unit according to an electromagnetic communication protocol.

[0032] Such an arrangement allows the receiving device to receive data using an analog light signal but also to transmit data using an electromagnetic signal.

[0033] According to one embodiment, the second communication unit is configured to communicate according to any of the electromagnetic communication protocols such as "RFID", "Bluetooth" or "BLE" for example.

[0034] The invention also relates to an analog signal transmission system comprising: a light transmission device for transmitting an analog signal in a first frequency band below 20 kHz comprising: a transmission unit configured to transmit a light signal in the visible spectrum, an excitation unit configured to excite the transmission unit: wherein the frequency or duration of excitation is determined as a function of a value of the analog signal, the emitted excitation frequency being in a second frequency band above 1 MHz; a light receiving device configured to generate an analog output signal comprising: a receiving unit having a latency time of less than 1µs configured to receive the light signal emitted by the light transmission device;an intensity measurement unit configured to measure the intensity of the light signal received by the receiving unit and to generate an analog output signal in the first frequency band.

[0035] According to the invention, the light signal is generated by exciting the transmission unit when the intensity of the light emitted by the transmission unit is zero or decreasing.

[0036] The invention also relates to a method for transmitting an analog signal in a first frequency band below 20 kHz comprising the following steps: excitation of a transmission unit configured to transmit a light signal in the visible spectrum, wherein the frequency or duration of excitation is determined as a function of a value of the analog signal, the excitation frequency being in a second frequency band greater than 1 MHz; emission of a light signal by the excited transmission unit; reception of a light signal by a receiving unit; measurement of the intensity of the light signal received by the receiving unit using an intensity measuring unit and to generate an analog output signal in the first frequency band, in which the receiving unit has a latency time of less than 1µs.

[0037] According to the invention, the light signal is generated by exciting the transmission unit when the intensity of the light emitted by the transmission unit is zero or decreasing.

[0038] The various aspects defined above, which are not incompatible, can be combined. Brief description of the figures

[0039] The invention will be even better understood with the aid of the detailed description set forth below, in conjunction with the accompanying drawings, in which: there figure 1 represents a schematic view of an analog signal transmission system comprising a light transmission device and a light reception device according to the present invention; figure 2 represents a first example of a stable regime as well as a transient regime according to the present invention; the figure 3 represents a second example of a stable regime as well as a transient regime according to the present invention; and the figure 4represents the intensity of a light analog signal as a function of time, the analog signal being transmitted by a light transmission device according to the present invention. Description with reference to the figures

[0040] There figure 1 represents an analog signal transmission set 11 comprising a light transmission device 10 and a light reception device 30.

[0041] The light transmission device 10 is configured for transmitting an analog signal 11 in a first frequency band below 20 kHz and includes a transmission unit 12 configured to transmit a light signal 20 in the visible spectrum. For the purposes of this invention, the visible spectrum includes electromagnetic waves with wavelengths between 380 nm and 780 nm. In one embodiment, such an arrangement allows the use of a transmission unit 12 already existing in a lighting network, for example. Such an arrangement is therefore environmentally efficient.

[0042] The transmission unit 12 includes a phosphorescent light-emitting diode, which makes it possible to obtain a transmission unit 12 capable of emitting light between two excitations 13 for a longer time than an incandescent bulb, for example.

[0043] The light transmission device 10 also includes an excitation unit 14 configured to excite the transmission unit 12. Such an arrangement allows the transmission of a light signal having a variable intensity and thus enables the transmission of an analog light signal as shown in the figure 4 . For the purposes of the present invention, an excitation 13 is an electrical signal sent to the transmission unit 12. The frequency of the excitation corresponds to the number of excitations 13 sent during a given time.

[0044] The excitation frequency or duration is determined based on a value of the analog signal 11, the excitation frequency being within a second frequency band above 1 MHz. Such an arrangement, and more specifically an excitation frequency within a second frequency band above 1 MHz, ensures illumination acceptable to the human eye. For the purposes of this invention, the term "acceptable to the human eye" means having a frequency high enough that the human eye cannot perceive any flickering.

[0045] In one embodiment, the excitation frequency is constant and preferably equal to 2 MHz. Such an excitation frequency makes it possible to obtain a higher quality analog signal without requiring a high-performance excitation unit 14, which would therefore consume more energy. Indeed, the higher the excitation frequency, the more precisely the emitted light signal varies. The generation of the analog light signal 11 is then possible by modifying the duration of each excitation 13, as shown in the figure. figure 4By adjusting the duty cycle, it is therefore possible to obtain a precise analog signal 11. This arrangement also avoids any stroboscopic or flickering effect that the transmission unit 12 might create. Indeed, with a constant excitation frequency, the impedance of the transmission unit 12, which is a light-emitting diode, remains constant. The variations in light intensity corresponding to the analog signal 11 are therefore invisible to the naked eye. In other words, the excitation unit 14 performs pulse-width modulation, the pulse corresponding to the excitation 13.

[0046] According to one embodiment, the excitation unit 14 is configured to excite the transmission unit 10 when said transmission unit 12 is in a transient regime 52, as opposed to a steady regime 50, as represented in figures 2 And 3According to a preferred embodiment, the excitation unit 14 is configured to excite the transmission unit 10 when said transmission unit 12 is in a falling transient regime 52 or in a steady state in which the light intensity is zero. For the purposes of the present invention, a falling transient regime 52 is a transient regime in which the intensity of the light emitted by the emission unit 12 is decreasing. Such a transient regime is obtained between two excitations 13.

[0047] The light receiver 30 is configured to generate an analog output signal 11 and includes a receiver unit 32 with a latency of less than 1 µs. The receiver unit 32 is configured to receive the light signal 20 emitted by the light transmission device 10. A receiver unit 32 with a latency of less than 1 µs can receive a light signal emitted by a transmission unit 12 excited by an excitation unit 14 at a frequency greater than 1 MHz.

[0048] The receiving unit 32 comprises an organic photovoltaic cell. This arrangement, and more specifically the phosphorescent nature of the diode coupled with the latency of the photovoltaic cell, allows for smoothing of the analog signal 11 generated at the output, without requiring demodulation. This arrangement makes it possible to obtain an energetically passive receiving unit 32, or even one that generates energy. In one embodiment, an organic cell allows for high reception gain and thus good reception quality even when the intensity of the received light signal is much lower than the ambient light intensity. For example, the device according to the invention is capable of receiving a 40 LUX signal in an ambient light of more than 10,000 LUX.

[0049] The light receiving device 30 also includes an intensity measuring unit 34 configured to measure the intensity of the light signal 20 received by the receiving unit 32 and to generate an analog output signal 11 in the first frequency band below 20 kHz.

[0050] In one embodiment, the light transmission device 10 comprises a first communication unit 16 configured to communicate with a second communication unit 36. The second communication unit 36 ​​is included in the light reception device 30. The first communication unit 16 and the second communication unit 36 ​​communicate with each other using an electromagnetic communication protocol, such as a radio protocol like RFID, Bluetooth, or BLE. This arrangement allows the transmission device 10 to transmit data using an analog light signal and also to receive data using an electromagnetic signal. Conversely, this arrangement allows the reception device 30 to receive data using an analog light signal and also to transmit data using an electromagnetic signal.

[0051] The invention also relates to a method for transmitting an analog signal 11 in a first frequency band below 20 kHz comprising the following steps: excitation of a transmission unit 12 configured to transmit a light signal 20 in the visible spectrum, wherein the frequency or duration of excitation is determined as a function of a value of the analog signal 11, the excitation frequency being in a second frequency band greater than 1 MHz; emission of a light signal 20 by the excited transmission unit 12; reception of a light signal 20 by a receiving unit 32; measurement of the intensity of the light signal 20 received by the receiving unit 32 using an intensity measuring unit 34 and to generate an analog output signal 11 in the first frequency band, wherein the receiving unit 32 has a latency time of less than 1µs.

[0052] According to one embodiment, the transmission process is carried out using the light transmission device 10 described above. Thus, the various characteristics and embodiments described with reference to the light transmission device 10 also apply to the transmission process.

Claims

1. A light transmission device (10) for transmitting an analog signal (11) in a first frequency band below 20 kHz, comprising: • a transmission unit (12) configured to transmit a light signal (20) in the visible spectrum; • an excitation unit (14) configured to generate an excitation (13), the excitation (13) being configured to excite the transmission unit (12); and wherein the frequency or duration of the excitation (13) is determined as a function of a value of the analog signal (11), the excitation frequency being within a second frequency band higher than 1 MHz, characterized in that the excitation unit (14) is configured to excite the transmission unit (12) when said transmission unit (12) is in a falling transient state or in a steady state in which the light intensity is zero.

2. The light transmission device (10) according to claim 1, wherein the transmission unit (12) comprises a phosphorescent light-emitting diode.

3. The light transmission device (10) according to any one of claims 1 and 2, wherein the light transmission device (10) comprises a first communication unit (16) configured to communicate with a remote second communication unit (36) according to an electromagnetic communication protocol.

4. A light reception device (30) configured to generate an analog output signal (11), comprising: • a reception unit (32) having a latency time of less than 1 µs, configured to receive a light signal (20) emitted by a light transmission unit (12); • an intensity measurement unit (34) configured to measure an intensity of the light signal (20) received by the reception unit (32) and to generate an analog output signal (11) in a first frequency band below 20 kHz, characterized in that the light signal (20) is generated by exciting the transmission unit (12) when the intensity of the light emitted by the transmission unit is zero or decreasing, the reception unit (32) comprising a photovoltaic cell for receiving the light signal.

5. The light reception device (30) according to claim 4, wherein the photovoltaic cell is an organic photovoltaic cell.

6. The light reception device (30) according to any one of claims 4 and 5, wherein the reception device (30) comprises a second communication unit (36) configured to communicate with a remote first communication unit (16) according to an electromagnetic communication protocol.

7. A system for transmitting an analog signal (11) comprising: ∘ a light transmission device (10) for transmitting an analog signal (11) in a first frequency band below 20 kHz, comprising: • a transmission unit (12) configured to transmit a light signal (20) in the visible spectrum, • an excitation unit (14) configured to excite the transmission unit (12); ∘ wherein frequency or duration of the excitation is determined as a function of a value of the analog signal (11), the excitation frequency being within a second frequency band higher than 1 MHz, and - a light reception device (30) configured to generate an analog output signal (11), comprising: • a reception unit (32) having a latency time of less than 1 µs, configured to receive the light signal (20) emitted by the light transmission device (10); • an intensity measurement unit (34) configured to measure an intensity of the light signal (20) received by the reception unit (32) and to generate an analog output signal (11) in the first frequency band, characterized in that the light signal (20) is generated by exciting the transmission unit (12) when the intensity of the light emitted by the transmission unit is zero or decreasing.

8. A method for transmitting an analog signal (11) in a first frequency band below 20 kHz, comprising the following steps: • exciting a transmission unit (12) configured to transmit a light signal (20) in the visible spectrum, wherein the frequency or duration of the excitation is determined as a function of a value of the analog signal (11), the excitation frequency being within a second frequency band higher than 1 MHz; • emitting a light signal (20) by the excited transmission unit (12); • receiving a light signal (20) by a reception unit (32); • measuring the intensity of the light signal (20) received by the reception unit (32) using an intensity measurement unit (34) and generating an analog output signal (11) in the first frequency band, wherein the reception unit (32) has a latency time of less than 1 µs, characterized in that the light signal (20) is generated by exciting the transmission unit (12) when the intensity of the light emitted by the transmission unit is zero or decreasing.