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EP-4740063-A1 - OPTICAL DEVICE EQUIPPED WITH A LIQUID-CRYSTAL DISPLAY

EP4740063A1EP 4740063 A1EP4740063 A1EP 4740063A1EP-4740063-A1

Abstract

Disclosed is a luminous device (1) for a motor vehicle, characterized in that it comprises a light source (2) and an optical device (3), the optical device being arranged so as to receive light rays generated by the light source, the luminous device comprising a layer comprising liquid crystals (4), a first layer (5) of an electrically conductive coating, and a second layer (6) of an electrically conductive coating, the luminous device further comprising a second electrical current source (10) connected to the second positive terminal and the second negative terminal of the second layer so as to make a periodic electrical current flow through this layer.

Inventors

  • KRICK, SEBASTIAN

Assignees

  • Valeo Vision

Dates

Publication Date
20260513
Application Date
20240704

Claims (10)

  1. [Claim 1] A lighting device (1) for a motor vehicle, characterized in that it comprises a light source (2) and an optical device (3), the optical device being arranged to receive light rays from the light source, the lighting device comprising a layer comprising liquid crystals (4), a first layer (5) of an electrically conductive coating, and a second layer (6) of an electrically conductive coating, said first layer and said second layer being two separate layers arranged on either side of the layer comprising liquid crystals, said first layer comprising a first positive terminal (P1) and said second layer comprising a first negative terminal (N1), the lighting device further comprising a first electric current source (9) connected to the first positive terminal and the first negative terminal so as to produce an alternating electric field passing through the layer comprising liquid crystals, at least one layer among said first layer and said second layer comprising a second positive terminal (P2) and a second negative terminal (N2), the lighting device further comprising a second electric current source (10) connected to the second positive terminal and the second negative terminal so as to circulate a periodic electric current in this layer, the light device further comprising a synchronization means configured to synchronize a phase of the electric current generated by the second current source with a phase of the electric current generated by the first current source.
  2. [Claim 2] A lighting device (1) according to the preceding claim, characterized in that a frequency of the second current source (10) is equal to a frequency of the first current source (10). current (9), or in that a frequency of the second current source (10) is equal to a multiple of a frequency of the first current source (9).
  3. [Claim 3] Luminous device (1) according to one of the preceding claims, characterized in that: - for each positive phase of the electric current generated by the first current source (9), the electric current generated by the second current source (10) comprises at least one positive phase and at least one negative phase, and/or in that: - for each negative phase of the electric current generated by the first current source (9), the electric current generated by the second current source (10) comprises at least one positive phase and at least one negative phase.
  4. [Claim 4] A lighting device (1) according to one of claims 1 or 2, characterized in that a frequency of the second current source (10) is equal to a frequency of the first current source (9), and in that: - for each positive phase of the electric current generated by the first current source, the electric current generated by the second current source comprises a positive phase and for each negative phase of the electric current generated by the first current source, the electric current generated by the second current source comprises a negative phase, or: - for each positive phase of the electric current generated by the first current source, the electric current generated by the second current source comprises a negative phase and for each negative phase of the electric current generated by the first current source, the electric current generated by the second current source includes a positive phase.
  5. [Claim 5] Luminous device (1) according to one of the preceding claims, characterized in that the second current source (10) is configured so as to circulate an alternating electric current between the second positive terminal (P2) and the second negative terminal (N2).
  6. [Claim 6] Luminous device (1) according to one of claims 1 to 4, characterized in that the second current source (10) is switched off for a negative phase of the first current source or for a positive phase of the first current source (9).
  7. [Claim 7] A lighting device (1) according to any preceding claim, characterized in that it comprises an electrical circuit (16) comprising a first direct current generator (21), a second direct current generator (22), a set of switching elements (S1, S2, S3, S4, S5, S6, S7, S8), and an electronic control unit (15) configured to control a state of each switching element so as to convert a direct current generated by the first direct current generator into an alternating current between the first positive terminal (P1) and the first negative terminal (N1), and so as to convert a direct current generated by the second direct current generator into a periodic current between the second positive terminal (P2) and the second negative terminal (N2).
  8. [Claim 8] Luminous device (1) according to one of the preceding claims, characterized in that the first current source (9) is configured to produce an alternating electric field passing through the layer comprising liquid crystals (4) of which the amplitude is between 50 volts and 100 volts, and/or whose frequency is between 25Hz and 100Hz
  9. [Claim 9] Method for controlling a light device (1) according to one of claims 1 to 8, characterized in that it comprises: - detection of a temperature lower than or equal to a threshold, then - the circulation of an electric current between the second positive terminal (P2) and the second negative terminal (N2) to heat the layer (6) of electrically conductive coating comprising the second positive terminal and the second negative terminal.
  10. [Claim 10] Method for controlling a light device (1) according to one of claims 1 to 8, characterized in that it comprises: - activating the first current source (9) so as to produce an alternating electric field passing through the layer comprising liquid crystals (4), and simultaneously: - activating the second current source (10) so as to cause a periodic electric current to flow in the layer comprising the second positive terminal (P2) and the second negative terminal (N2).

Description

DESCRIPTION TITLE: Optical device equipped with a liquid crystal display Technical field of the invention [0001] The invention relates to a lighting device for a motor vehicle, the lighting device comprising an optical device provided with a liquid crystal screen, in particular of the PDLC (acronym for the English term "Polymer Dispersed Liquid Crystal") type. The invention also relates to a method for controlling such a lighting device. State of the prior art [0002] A motor vehicle is provided with lighting devices for illuminating the environment of the vehicle and making the vehicle clearly visible to other road users. A vehicle thus generally comprises at least main beam headlights, dipped beam headlights and position lights. The lighting devices also contribute to the aesthetic appearance of the vehicle by providing an original light signature. This light signature must remain clearly visible without being dazzling regardless of the ambient light conditions. The lighting devices must thus produce light beams whose intensity varies according to the light conditions, and according to the needs of a user of the vehicle. For example, vehicles equipped with position lights whose light intensity varies depending on whether the vehicle is used during the day or at night are known. [0003] This diversity of needs encourages motor vehicle manufacturers to provide lighting systems equipped with numerous lighting devices, each intended to perform a particular lighting function. Vehicles thus carry complex, heavy and bulky lighting systems. [0004] Furthermore, a motor vehicle must operate in very wide temperature ranges. In particular, the lighting devices of motor vehicles must remain fully functional at low temperatures, in particular at negative temperatures, or even at -20°C, or even -40°C. Presentation of the invention [0005] The aim of the invention is to provide a lighting device for a motor vehicle, remedying the above drawbacks and improving the lighting devices known from the prior art. [0006] More specifically, a first object of the invention is a light device capable of producing a light beam whose intensity is easily controllable and capable of operating at low temperature. Summary of the invention [0007] The invention relates to a light device for a motor vehicle, the light device comprising a light source and an optical device, the optical device being arranged so as to receive light rays from the light source, the light device comprising a layer comprising liquid crystals, a first layer of an electrically conductive coating, and a second layer of an electrically conductive coating, said first layer and said second layer being two separate layers arranged on either side of the layer comprising liquid crystals, said first layer comprising a first positive terminal and said second layer comprising a first negative terminal, the light device further comprising a first source of electric current connected to the first positive terminal and the first negative terminal so as to produce an alternating electric field passing through the layer comprising liquid crystals. liquid crystals, at least one layer among said first layer and said second layer comprising a second positive terminal and a second negative terminal, the light device further comprising a second electric current source connected to the second positive terminal and the second negative terminal so as to circulate a periodic electric current in this layer, the light device further comprising a synchronization means configured to synchronize a phase of the electric current generated by the second current source with a phase of the electric current generated by the first current source. [0008] According to one embodiment, a frequency of the second current source is equal to a frequency of the first current source, or a frequency of the second current source is equal to a multiple of a frequency of the first current source. [0009] According to one embodiment: - for each positive phase of the electric current generated by the first current source, the electric current generated by the second current source comprises at least one positive phase and at least one negative phase, and/or: - for each negative phase of the electric current generated by the first current source, the electric current generated by the second current source comprises at least one positive phase and at least one negative phase. [0010] According to one embodiment, a frequency of the second current source is equal to a frequency of the first current source, and: - for each positive phase of the electric current generated by the first current source, the electric current generated by the second current source comprises a positive phase and for each negative phase of the electric current generated by the first current source, the electric current generated by the second current source comprises a negative phase, or: - for each positive phase of the electric current generated by