Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
  • B60K35/80—Arrangements for controlling instruments
  • B60K35/81—Arrangements for controlling instruments for controlling displays
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
  • B60K35/10—Input arrangements, i.e. from user to vehicle, associated with vehicle functions or specially adapted therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
  • B60K35/20—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor
  • B60K35/21—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor using visual output, e.g. blinking lights or matrix displays
  • B60K35/23—Head-up displays [HUD]
  • B60K35/233—Head-up displays [HUD] controlling the size or position in display areas of virtual images depending on the condition of the vehicle or the driver
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/01—Head-up displays
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/01—Head-up displays
  • G02B27/0101—Head-up displays characterised by optical features
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
  • B60K2360/20—Optical features of instruments
  • B60K2360/23—Optical features of instruments using reflectors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
  • B60K2360/20—Optical features of instruments
  • B60K2360/33—Illumination features
  • B60K2360/334—Projection means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
  • B60K2360/20—Optical features of instruments
  • B60K2360/33—Illumination features
  • B60K2360/349—Adjustment of brightness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
  • B60K2360/40—Hardware adaptations for dashboards or instruments
  • B60K2360/48—Sensors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K2360/00—Indexing scheme associated with groups B60K35/00 or B60K37/00 relating to details of instruments or dashboards
  • B60K2360/60—Structural details of dashboards or instruments
  • B60K2360/66—Projection screens or combiners

Definitions

• the present invention relates to the technical field of head-up display.
• the present invention relates in particular to a head-up display device, for example for a motor vehicle.
• Head-up display devices comprising a housing, an image generation device and an optical system: the image generation device is arranged inside the housing and designed to generate a beam luminous ; the optical system is configured to project the light beam in the direction of a partially transparent plate through a window formed in the housing.
• the light beam After partial reflection on the partially transparent blade, the light beam reaches the eyes of the driver so as to form a virtual image seen by the driver beyond the partially transparent blade, that is to say, in the usual applications, at the front of the vehicle.
• the intensity of the light beam generated by the image generation device is usually adjusted as a function of the ambient brightness: the higher the ambient brightness, the more the intensity of the light beam must also be high.
• the invention provides a head-up display device, a housing, an image generation device and an optical system
• the image generation device comprising a screen, being arranged in the interior of said housing and being designed to generate a light beam, said optical system being configured to project said light beam towards a partially transparent blade through a window formed in said housing
• said head-up display device comprising in besides a protection module capable of controlling a reduction in intensity of said light beam generated by said image generation device, said head-up display device comprising: a first sensor capable of determining an external brightness; and a second sensor capable of measuring radiation emitted by said screen; said protection module being able to control a reduction in intensity of said light beam on the basis of said external brightness and of said radiation.
• the protection module can thus for example be activated and reduce the intensity of the light beam in order to limit the production of heat inside the case by the imaging device.
• said second sensor has a field of view oriented towards said image generation device such that said radiation is representative of a surface temperature of said screen
• said first mirror comprises an optical filter arranged on its reflecting surface and having a reflection coefficient of less than 5% for radiation included in a given range of infrared wavelengths;
• said second sensor is an infrared sensor
• said second sensor comprises a matrix of photoelectric cells
• the first sensor is designed to detect a solar light beam entering said housing
• said protection module comprises a device for measuring an ambient temperature of said image generation device
• said protection module is designed to control said reduction when said ambient temperature is above a threshold
• said screen comprises at least one semiconductor element
• said head-up display device comprises a circuit for measuring a junction temperature of said semiconductor element
• - Said protection module is designed to control a reduction in intensity of the light beam when the junction temperature is above a threshold.
• the invention also provides a method of protecting a head-up display device comprising: a housing; an image generation device arranged inside said housing, comprising a screen and adapted to generate a light beam; a optical system configured to project said light beam towards a partially transparent plate and comprising a first mirror arranged to reflect said light beam; a first sensor; a second sensor; and a protection module; said method comprising the following steps:
• the step of measuring the radiation is triggered on the basis of said external luminosity
• the step of reducing the intensity of the modulated beam is triggered on the basis of said external brightness
• said protection method comprises the following steps: i) a step of determining an ambient temperature by a temperature sensor; and ii) a step of determining a junction temperature by a measuring circuit; and the reduction in intensity of the modulated light beam is performed on the basis of said ambient temperature and said junction temperature;
• said protection method comprises a step of determining, on the basis of said radiation and a time constant of said screen, a maximum temperature representative of the rise in temperature of said screen;
• - Said protection module controls a reduction in intensity of said modulated light beam when said maximum temperature is greater than a limit temperature of said screen.
• FIG. 1 shows schematically in section a head-up display device according to the invention
• FIG. 2 represents a reduction curve based on a temperature measurement
• FIG. 3 schematically shows in perspective a second sensor and a screen belonging to the head-up display device of FIG. 1;
• FIG. 4 represents a block diagram of a sequence of steps allowing the implementation of a thermal protection method
• FIG. 5 represents a block diagram of a sequence of steps making it possible to determine a reduction coefficient used in the method of FIG. 4.
• a head-up display device 1 is described in the case where it is used in a motor vehicle.
• the head-up display device 1 comprises an image generation device 10, an optical system 20, a first sensor 65, a second sensor 60 and a protection module 30.
• the head-up display device 1 is controlled by a computer.
• the computer is programmed to control and / or connect the various elements of the head-up display device 1.
• the computer is a vehicle computer.
• the head-up display device 1 could comprise a dedicated computer.
• the image generation device 10 is designed to generate a light beam called the modulated light beam L.
• the image generation device 10 comprises a light source 12 and a screen 11.
• the screen 11 consists of a matrix of elements whose transmittance varies over time.
• the screen 11 receives a source light beam generated by the light source 12 and transmits the modulated light beam L.
• the light source 12 is polychromatic to form color images. Thanks to its matrix of elements, the screen 11 spatially modulates the source light beam so as to form the modulated light beam L.
• the screen 11 is a TFT type liquid crystal screen (standing for “thin film transistor”), that is to say a matrix of liquid crystal cells each controlled by a transistor in thin film (hence the name of the screen says TFT).
• three cells each associated with a colored filter, for example one for blue, one for green and one for red, make it possible to control the transmittance, by orienting the liquid crystals, in a stable manner and with a low response time.
• a colored filter for example one for blue, one for green and one for red
• a rear face of a diffuser is scanned by a laser beam generated by a set of laser diodes, the scanning being for example carried out by a movable mirror. Then, a front face of the diffuser generates the modulated light beam.
• the optical system 20 is arranged to project the modulated light beam L in the direction of a partially transparent blade 70 along a determined path.
• the modulated light beam L is reflected by the partially transparent plate 70 towards an observation zone where the eyes of the driver are located.
• the path of the modulated light beam L between the image generation device 10 and the partially transparent plate 70 defines an optical path.
• the partially transparent blade 70 is oriented so as to reflect a part of the modulated light beam L in the direction of an observation zone in which the eyes of the driver are located, so as to form a virtual image.
• the partially transparent blade 70 may be part of a vehicle windshield or a combiner, that is to say a partially transparent blade 70 dedicated to the head-up display. Such a combiner would be placed between the windshield and the driver's eyes.
• the virtual image contains indications or information intended for the driver of the vehicle, for example in the form of regulatory symbols and / or a speedometer and / or an engine speed indicator and / or a fault indicator and / or a navigation instruction.
• the optical system 20 here comprises a first mirror 21 which is a plane mirror.
• Optical system 20 also includes a second mirror 25 which is a concave mirror.
• the second concave mirror 25 allows for example the enlargement of small images generated by the image generation device 10 to form virtual images of suitable size.
• the second mirror 25 is mobile, for example in rotation, so as to adjust the position of the virtual image to the observation zone, which depends on the size of the driver.
• the first mirror 21 orients the modulated light beam L produced by the image generation device 10 towards the second mirror 25.
• the head-up display device 1 is here included in a protective housing 50 or a casing.
• a window 51 is made in the housing 50 to allow the modulated light beam L to propagate towards the partially transparent plate 70.
• the window 51 can be covered by a transparent material such as a glass slide.
• the adjective “inside” refers to the inside of the head-up display device 1, therefore here inside the housing 50.
• the adjective “outside” refers to the outside. of the head-up display device 1 therefore here on the outside of the housing 50.
• the adjective “outside” refers for example to the interior of the vehicle.
• a solar light beam LS can penetrate inside the head-up display device 1, here by the window 51. This happens in particular when the sun, the partially transparent plate 70 and the second mirror 25 are substantially aligned, as shown in FIG. 1.
• FIG. 1 represents a particular example of propagation of the solar light beam LS.
• the solar light beam LS travels the optical path in the opposite direction.
• This scenario corresponds to the most damaging situation for the head-up display device 1 since the second mirror 25 focuses, after reflection on the first mirror 21, the solar light beam LS at the center of the screen 11.
• the solar light beam LS can illuminate other areas of the screen 11 but is less focused.
• the screen 11 is relatively absorbent. Thus, when the solar light beam LS reaches the screen 11, the solar light beam LS rapidly causes heating of the screen 11 and more generally of the image generation device 10. Such heating is detrimental to the operation of the device. image generation device 10 and can go as far as its deterioration. For example here, from a certain temperature, the liquid crystals of the screen 11 can lose their polarization.
• the head-up display device 1 comprises a protection module 30 capable of controlling an intensity reduction of the modulated light beam L.
• the protection module 30 can for example control a reduction of the intensity of the source light beam emitted by the light source 12, until it stops total if necessary.
• the protection module 30 can for example control a reduction in the electric current supplied to the light source 12.
• the protection module 30 may include device 40 for measuring an ambient temperature TA of the image generation device 10.
• the measuring device 40 is located nearby of the screen 11 or on the electronic card of the light source 12.
• the measuring device 40 is for example a thermistor with a negative temperature coefficient.
• the protection module 30 is designed to control the reduction in intensity of the modulated light beam L when the ambient temperature TA is greater than an ambient threshold.
• the ambient threshold is for example between 60 ° C and 100 ° C, the ambient threshold is preferably between 70 ° C and 100 ° C.
• This measurement of ambient temperature TA makes it possible to set up a so-called "derating" reduction strategy, characterized by a reduction in the performance of the image generation device 10.
• This strategy consists in defining the maximum intensity of the beam modulated light L generated by the image generation device 10, that is to say the maximum luminance of the virtual image, as a function of the ambient temperature TA.
• the amplitude of the reduction in intensity can be given by a reduction curve called "derating curve. »Defined in three intervals: i) an interval where the ambient temperature TA is less than or equal to a threshold value TA1, the image generation device 10 can then operate at its maximum capacity, the third coefficient C3 is then equal to 1; ii) an interval where the ambient temperature TA is greater than the threshold value TA1 and less than a maximum value TA2, the protection module 30 can decrease the intensity of the modulated light beam L, the amplitude of the reduction is obtained by a projection on a decreasing linear curve, the third coefficient C3 is then between 0 and 1; iii) an interval where the ambient temperature TA is greater than the maximum value TA2, the protection module 30 can order the stopping of the image generation device 10, the third coefficient C3 is then equal to 0.
• the image generation device 10 comprises a semiconductor element, for example a semiconductor element of the screen 11 or a light emitting diode of the light source 12.
• the head-up display device 1 comprises a dedicated measuring circuit.
• the protection module 30 can order the stopping of the image generation device 10.
• the protection module 30 can also be designed to control a reduction in the intensity of the modulated light beam L when the junction temperature TJ is greater than a junction threshold.
• the junction threshold is preferably between 95 ° C and 110 ° C, which conventionally corresponds to the thermal limits of a TFT screen.
• the junction threshold can for example be equal to 110 ° C.
• the protection module 30 can decrease the intensity of the modulated light beam L to regulate the junction temperature TJ.
• the amplitude of the reduction, represented by a fourth coefficient C4, of intensity can be given by a second reduction curve defined in three intervals.
• the head-up display device 1 comprises:
• the first sensor 65 which is able to determine an exterior brightness LE
• the protection module 30 is then able to control a reduction in the intensity of the light beam L on the basis of the external luminosity LE and of the radiation RA.
• the intensity of the modulated light beam L at a given time also depends on the external brightness LE. It is important to consider the external luminosity LE around the driver to adapt the luminance of the virtual image, for example to adapt to the passage in a tunnel, to the exit of a tunnel or to a dazzling situation.
• the protection module 30 is therefore connected to the first sensor 65 which is designed to determine an external luminosity LE which is here associated with solar radiation.
• the first sensor 65 is also designed to detect a solar light beam LS entering the image capture device 1 through the window 51 of the housing 50.
• the first sensor 65 is arranged outside the housing 50, near the window 51.
• the first sensor 65 may include a light guide, for example an optical fiber, to determine an exterior brightness LE coming from a particular direction.
• the The light guide is preferably oriented in the direction defined by the window 51 and the partially transparent plate 70 to detect a solar light beam LS entering the head-up display device 1. Provision could also be made for the first sensor to be arranged inside the housing and oriented towards the window or else the first sensor is placed in the passenger compartment of the vehicle.
• this first sensor 65 it is possible to set up a so-called “dimming" adaptation strategy to adapt the luminance of the virtual image as a function of the external luminosity LE.
• This adaptation strategy can cause the image generation device 10 to increase or decrease the intensity of the modulated light beam L by virtue of a first coefficient Cl.
• the first coefficient Cl may be less than 1 and in a glare situation, the first coefficient Cl may be greater than 1.
• the head-up display device 1 also includes the second sensor 60.
• the second sensor 60 is able to measure RA radiation emitted by the screen 11 inside the housing 50
• the protection module 30 can then control the reduction in intensity of the modulated beam L on the basis of the radiation RA.
• the protection module 30 can for example control the reduction of intensity when the radiation RA is greater than a threshold.
• the second sensor 60 is oriented towards the screen 11.
• the orientation is predetermined such that RA radiation is representative of a surface temperature of the screen 11
• oriented towards the screen 11 is meant that the screen 11 is included in a field of vision C of the sensor which can be defined by a solid angle through which the second sensor 60 is sensitive to electromagnetic radiation.
• a main observation axis P of the second sensor 60 is oriented towards a center CR of the screen 11.
• the main observation axis P is defined as the direction along which the second sensor 60 is the most sensitive to radiation and corresponds to the average direction of the field of vision C.
• the highest temperature is located at CR center of the screen 11, it is therefore important to measure the temperature at the CR center with good precision.
• the second sensor 60 is therefore arranged to measure the RA radiation emitted by the screen 11. Since the RA radiation emitted by the screen 11 is representative of the temperature of the screen 11, the measurement of the radiation RA makes it possible to estimate the temperature at the surface of the screen 11. The measurement of an intensity radiated by the screen 11 at a determined wavelength, or in a determined wavelength range, makes it possible, like a black body, to determine the temperature at the surface of the screen 11.
• the second sensor 60 is placed near the first mirror 21, as shown in FIG. 1.
• the second sensor 60 is located at a distance D from the screen 11 preferably between 40 and 100 mm.
• the field of view C of the second sensor 60 is defined by a first angle ALPHA representing the window of the field of view C in a first direction and by a second angle BETA representing the window of the field of view C in a second direction orthogonal to the first .
• the first angle ALPHA is preferably between 20 ° and 120 °.
• the second BETA angle is preferably between 20 ° and 120 °.
• the second sensor 60 is capable of operating at least between -40 ° C and 100 ° C.
• the second sensor 60 is an infrared sensor.
• the second sensor 60 is primarily sensitive to a given infrared wavelength range, for example wavelengths less than 700nm.
• mainly sensitive is meant that the second sensor 60 is for example 5 to 10 times more sensitive to infrared radiation than to visible radiation.
• the sensor 60 has a passband located in the infrared.
• An infrared sensor makes it possible to set up an effective solar protection strategy since in the infrared range, the RA radiation emitted by the screen 11 is more representative of its temperature than in the visible range.
• the modulated light beam L consists of wavelengths included in the visible range, the latter does not disturb the operation of the second sensor 60.
• the first mirror 21 here comprises an optical filter 22 disposed on its reflecting surface and having a reflection coefficient of less than 5% for radiation within a given range of infrared, for example for the lengths d wave less than 700 nm. Thanks to this optical filter 22, the infrared part of the solar light beam LS does not reach the screen 11 and does not cause it to heat up. Equipped with the optical filter 22, the first mirror 21 is equivalent to a “cold mirror”, the infrared part of a light beam is transmitted through the first mirror 21 and only the visible part is reflected.
• the radiation RA measured by the second sensor 60 therefore does not depend on a possible partial reflection of the solar light beam LS on the screen 11.
• the solar light beam LS reflected on the screen 11 can only generate radiation in the visible range towards the second sensor 60.
• the second sensor 60 By means of calibrations, it is possible to determine the temperature of the screen 11 on the basis of its radiation RA, in particular its radiation RA in the infrared range. For a given positioning of the second sensor 60, it is for example possible to vary the temperature of the screen 11 and carry out radiation measurements in order to construct a mathematical correlation model. The second sensor 60 therefore makes it possible here to determine, in real time, the temperature at the surface of the screen 11.
• the second sensor 60 comprises a matrix of photoelectric cells. This matrix makes it possible to determine the temperature at several points on the surface of the screen 11. Such a second sensor 60 is capable of giving for example 64 temperature values when it comprises a matrix of 8 ⁇ 8 photoelectric cells.
• This matrix of photoelectric cells makes it possible to determine a temperature distribution DT at the surface of the screen 11.
• This temperature distribution DT notably contains data on the location and the temperature of hot spots which may form on the screen. screen 11 by focusing the solar light beam LS.
• a hot spot can be very local, which can damage the screen 11 without significantly raising the ambient temperature TA.
• Such a hot point can come from a line of focusing, that is to say a strong illumination in the visible range coming from the sun.
• the protection module 30 can control the reduction in intensity of the modulated light beam L, that is to say a reduction in the performance of the image generation device 10, on the basis of the RA radiation emitted by the screen 11.
• the intensity of the modulated light beam L at a given time after reduction by the protection module 30 is hereinafter called the corrected intensity IC of the modulated light beam L.
• the corrected intensity IC therefore depends on the reduction in intensity controlled on the basis of the radiation RA measured by the second sensor 60, i.e. on the basis of the temperature distribution DT at the surface of the screen 11.
• the corrected intensity IC corresponds to a setpoint intensity, weighted, among other things, by a second coefficient C2 determined on the basis of the radiation RA.
• the setpoint intensity is for example determined by the driver to achieve a given luminance of the virtual image.
• the second coefficient C2 can for example be determined on the basis of the hottest temperature determined at the surface of the screen 11, such as the hottest hot spot. Thus, when the temperature at a point exceeds a threshold value, the second coefficient can be set at a value less than 1, for example by following a reduction curve based on the temperature of the hottest point.
• the method of thermal protection of the head-up display device 1 comprises:
• the solar light beam LS is an external thermal stress which can be three to four times greater than the internal thermal stresses and which can generate rapid local heating, it is therefore necessary to detect these hot spots in order to anticipate the heating.
• steps e2 and / or e5 can be performed only when a solar light beam LS enters the housing 50.
• the first sensor 65 is used. to estimate the conditions where a solar light beam LS enters the housing 50, either directly for example by virtue of the light guide described above, or indirectly on the basis of the external luminosity LE.
• steps e2 and e5 are triggered when the exterior brightness LE is greater than a threshold value. Provision can also be made for steps e2 and e5 to be triggered when the first coefficient C1 is greater than 1, that is to say under conditions of strong sunlight.
• steps e2 and e5 can therefore depend on the exterior brightness LE determined in step el. This triggering of steps e2 and e5 makes it possible to save energy and avoid untimely reductions in the intensity of the modulated light beam L.
• step el the external luminosity LE makes it possible to determine the first coefficient C1.
• step e2 the radiation RA makes it possible to determine the second coefficient C2.
• step e5 the protection module 30 can then calculate the corrected intensity IC by weighting the setpoint intensity by the first coefficient C1 and / or by the second coefficient C2.
• FIG. 5 represents a sequence of steps making it possible to determine the second coefficient C2 on the basis, among other things, of the radiation RA measured by the second sensor 60.
• the protection method comprises a step e21 of determining a temperature distribution DT on the surface of the screen 11.
• the temperature distribution DT is determined on the basis of the radiation RA emitted by the screen 11
• the temperature distribution DT is updated at regular time intervals thanks to an internal clock of the protection module 30. After each time interval, the temperature distribution DT is recorded in a table, here in a memory of the protection module 30. The table then contains a series of temperature distributions DT.
• the protection method comprises a step e22 of calculating a dynamic average MD of the temperature of the screen 11 on the basis of the series of temperature distributions DT.
• a digital filter is integrated into the protection module 30.
• the coefficients of the filter can be dynamic, for example updated at each time interval on the basis of the temperature distributions recorded in the table.
• the maximum temperatures representative of the hot spots may be given greater weight in the calculation of the dynamic mean MD.
• the dynamic mean MD is representative of the temporal evolution of the temperature of the screen 11.
• the dynamic mean MD is for example representative of the hot spots, of the mean temperature and of the temperature gradients.
• the dynamic average MD makes it possible to monitor rapid and local increases in the temperature at the surface of the screen 11.
• the first time intervals for example the first three, are not. taken into account to avoid outliers.
• the protection method then comprises a step e23 of calculating a maximum temperature TMAX on the basis of the dynamic mean MD and of a time constant CT of the screen 11.
• the maximum temperature TMAX is an estimate of the temperature of the screen 11, in permanent mode or after a determined period, if the thermal stress imposed on the screen 11 remains invariable, that is to say the temperature that the screen 11 will reach if the thermal stresses , in particular the sunshine, remain constant.
• the maximum temperature TMAX which is representative of the temperature rise of the screen 11, is thus determined on the basis of the radiation RA and of the time constant CT.
• an estimator is integrated into the protection module 30.
• the estimator can for example be a neural network trained on measurements obtained in calibration.
• the time constant CT is a characteristic parameter of the screen 11.
• the time constant CT represents the thermal capacity of the screen 11, that is to say its propensity to heat up when it receives. Energy.
• the time constant CT depends in particular on the materials in which the screen 11 is made. The addition of additional layers on the screen 11, such as films and glass plates, makes it possible to adjust the time constant CT.
• the estimation of the maximum temperature TMAX makes it possible to decide whether a reduction in the intensity of the light beam L is necessary. If the maximum temperature TMAX is lower than a limit temperature of the screen 11, the intensity of the light beam L is not reduced.
• the second coefficient C2 can be fixed at 1. If the maximum temperature TMAX is greater than the limit temperature of the screen 11, the intensity of the light beam L is reduced. The second coefficient C2 can be fixed at a value less than 1.
• the limit temperature of the screen 11 is the temperature at which the screen 11 ceases to function normally.
• the limit temperature of the screen 11 can be the ambient threshold defined previously.
• the protection module 30 can thus control a reduction in the intensity of the modulated light beam L when the maximum temperature TMAX is greater than the limit temperature of the screen 11.
• the protection method comprises a step e24 of determining the second coefficient C2 on the basis of the maximum temperature TMAX and of the time constant CT.
• the greater the maximum temperature TMAX the lower the second coefficient C2, that is to say close to 0, to anticipate the rise in temperature of the screen 11 to a high value.
• the lower the time constant CT the lower the second coefficient C2, since the screen 11 rises rapidly in temperature for a given thermal stress, for example a given sunshine.
• the thermal protection method further comprises steps el, e2 and e5:
• step e3 the ambient temperature TA makes it possible to determine the third coefficient C3.
• step e4 the junction temperature TJ makes it possible to determine the fourth coefficient C4.
• the protection module in this second embodiment, can then control the reduction in intensity of the modulated light beam L on the basis of the ambient temperature TA and / or on the basis of the temperature junction TJ.
• the protection module 30 can then calculate the corrected intensity IC by weighting the setpoint intensity by the third coefficient C3 and / or by the fourth coefficient C4.
• the protection module 30 is therefore based on the following parameters to control a reduction in intensity of the modulated light beam L:
• the protection module 30 calculates the corrected intensity IC by weighting the setpoint intensity both by the first coefficient Cl, by the second coefficient C2, by the third coefficient C3 and by the fourth coefficient C4.
• the different protection strategies (reduction, reduction or based on the temperature distribution) interact optimally to provide the driver with the brightest virtual image possible while protecting the driver. image generation device 10. This makes it possible to increase the life of the image generation device 10.
• the protection module 30 can control the closing of the window 51 by means of a movable part so as to prevent the solar light beam LS to penetrate inside the head-up display device 1. Provision can also be made for the second mirror 25, which here is mobile, to be moved to a protection position where the path of the modulated light beam L between the optical system 10 and the partially transparent plate 70 is interrupted, that is to say towards a position where the solar light beam LS cannot reach the image generation device 10.

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• 2020
  • 2020-02-26 FR FR2001870A patent/FR3107601A1/fr active Pending
• 2021
  • 2021-02-24 EP EP21706315.5A patent/EP4110641A1/de active Pending
  • 2021-02-24 CN CN202180017409.2A patent/CN115175822A/zh active Pending
  • 2021-02-24 WO PCT/EP2021/054537 patent/WO2021170639A1/fr not_active Ceased

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