FR3052416B1 - OPTICAL SENSOR PROTECTION DEVICE AND OPTICAL SENSING SYSTEM FOR AUTOMOTIVE VEHICLE - Google Patents

Abstract

The invention relates to a protection device (5) for an optical sensor (3) for a motor vehicle, comprising a vibration device (9) comprising at least one transmitter (11) capable of generating ultrasonic waves (US). According to the invention, said at least one transmitter (11) is adapted to be arranged to generate ultrasonic waves (US) in the field of view of the optical sensor (3), so as to atomize fluid particles (12). ) when they enter the ultrasonic field formed by the generated ultrasonic waves (US). The invention also relates to a corresponding optical detection system (1).

Description

Device for protecting an optical sensor and optical detection system for an associated motor vehicle

The present invention relates to the field of driving assistance and in particular to optical detection systems, comprising for example cameras, installed on certain vehicles. More particularly, the invention relates to a device for protecting an optical sensor such as a camera, in particular of such a detection system. The invention also relates to an optical detection system such as a rear vision system comprising an optical sensor and an associated protection device.

An optical sensing system is any system comprising optical sensors, such as cameras, laser sensors (commonly called LIDARs), or other sensors based on the emission and / or detection of light in the visible or invisible spectrum. 'Man, especially the infrared.

Nowadays, especially rear vision cameras equip a large number of motor vehicles, and are part of a parking aid system that makes it easier to park in a location without turning and to detect obstacles. located at the rear of the vehicle.

Cameras are known which are installed inside the cockpit against the rear window / bezel looking towards the rear from the rear window of the vehicle. These cameras are well protected from external climatic influences and can for example benefit from the defrosting and cleaning systems of the rear window, for example a heating wire integrated in the glass of the rear window.

However, the angle of view is not optimal, especially for a parking aid and for this reason, it is preferred that the camera is arranged at the bumper or the rear bodywork or at the level of the plate. rear registration of the vehicle. In this case, the camera is highly exposed to the projections of dirt that can be deposited on its optics and thus reduce its effectiveness, or even make it inoperative. Particularly in rainy weather, there are projections of rain and dirt that can greatly affect the operability of the optical detection system such as a rear vision system comprising such a camera. The surfaces of the optics of the cameras must be cleaned to ensure that they are in good working order.

To counteract the deposition of dirt on the camera, it is known to arrange a device for cleaning the optics of the camera, usually a nozzle of cleaning fluid, close to it, to remove the polluting elements that are deposited over time. However, the optics of the camera, which is a relatively fragile element, is not protected from projections that could damage it.

It is also known to mount the camera inside the outer lining of the vehicle, and to protect it from external aggressions via a window or protective window attached to the cladding. Although the camera is protected from external aggression, the camera remains subject to the deposition of pollutants inside the vehicle skin, and the cleaning of the camera is particularly difficult in such an arrangement.

According to a known solution for example of the document FR2841488 in the name of the Applicant, a nozzle is provided and for example projects a cleaning liquid under pressure on the optics of the camera such as a protective window of the camera. The nozzle is further assisted by vibration means for removing stubborn dirt from the protective window of the camera. However, it has been found that the operation of this vision system can be optimized. Indeed, after the projection of a cleaning liquid on the optics of the camera, there may be drops attached to the protective glass, which damages and deforms the image taken by the camera. The presence of the cleaning liquid drops results from the fact that the cleaning liquid does not slide easily on the surface of the optics of the camera. In addition, the evaporation of the drops on the protective glass leaves traces that can be seen on the image taken by the camera.

A new concept appeared since does not tend to clean the camera as soon as it is dirty to maintain its operability, but to keep it clean permanently against the projections of rain or dust. For this purpose, it is known to continuously project an air curtain in front of the screen camera which prevents the deposition of dirt.

The present invention proposes to remedy at least partially the disadvantages mentioned above by presenting an alternative of a protection device of an optical reciprocating sensor for preventing the deposit of dirt on the optical sensor such as a camera. To this end, the subject of the invention is a device for protecting an optical sensor for a motor vehicle, comprising a vibration device comprising at least one transmitter capable of generating ultrasonic waves. According to the invention, said at least one transmitter is adapted to be arranged to generate ultrasonic waves in the field of view of the optical sensor, so as to atomize fluid particles when they enter the ultrasonic field formed by the generated ultrasonic waves.

The atomized particles are thus reduced into smaller particles which can more easily be deflected, for example by means of an additional forced air flow, so that these fine particles do not contaminate the optical sensor, in particular the optical such as a lens of the optical sensor.

The protection device according to the invention may further comprise one or more of the following characteristics taken alone or in combination: the transmitter is intended to be arranged to emit ultrasonic waves in a direction substantially perpendicular to the optical axis optical sensor; the transmitter is arranged near the optical sensor and out of the field of view of the optical sensor; the transmitter comprises at least one piezoelectric transducer made of ceramic material; the vibration device comprises a plurality of emitters intended to be distributed around the field of view of the optical sensor; the vibration device is configured to generate stationary ultrasonic waves, and comprises for each transmitter, an opposite emitter or an associated resonant receiver; the protection device comprises means for evacuating the residues of the particles after atomization; the protection device comprises at least one nozzle for projecting an air flow in front of the optical sensor, the air flow making it possible to evacuate the residues of the particles after atomization. Thus, the projected air has a function relating to the cleaning of the optics of the optical sensor; the optical sensor comprises an optical element such as a lens, and the projection nozzle is configured to deliver a flow of air flush with the optic; the airflow is preferably laminar; - The protection device comprises a heating means of the air flow. The invention also relates to an optical detection system for a motor vehicle comprising an optical sensor and an optical sensor protection device as defined above.

According to one aspect of the invention, said at least one transmitter is mechanically decoupled from the optical sensor. Other advantages and features will appear on reading the description of the invention, as well as the appended drawings in which: - Figure 1 is a schematic cross-sectional view of an optical detection system comprising an optical sensor and a protection device of the optical sensor, and - Figure 2 is a schematic view showing the optical sensor and an alternative embodiment of the protective device of the optical sensor.

In these figures, the identical elements bear the same reference numbers.

The following achievements are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments may also be combined or interchanged to provide other embodiments.

FIG. 1 shows a first embodiment of an optical detection system 1 according to the invention for a motor vehicle.

The detection system is for example a rear vision system for a motor vehicle intended to be mounted at the rear of a motor vehicle, for example at a bumper or a license plate (not shown ). It can also for example be mounted on the sides of the vehicle, for example in complement and / or replacement of side mirrors.

The optical detection system 1 comprises an optical sensor 3, in particular for shooting, and a protection device 5 for this optical sensor 3.

The optical sensor 3 is for example an optical image sensor 3 such as a camera. The optical sensor 3 is for example a CCD sensor (for "coupled coupled device" or a charge coupled device) or a CMOS sensor composed of a matrix of miniature photodiodes. According to another variant, it may be a sensor for remote sensing laser called LIDAR sensor, acronym in English of "light detection and ranging".

The optical sensor 3 comprises an optical axis optic 7 A. This optic 7 is for example convex (convex) of convexity oriented towards the outside of the optical sensor 3, such as a so-called fish eye optics ("fish-eye " in English). In general, the optics 7 are any optical element, such as a lens and / or a protective glass, arranged in front of the optical sensor 3.

The protection device 5 comprises a vibration device 9. The vibration device 9 may comprise one or more emitters 11 capable of generating ultrasonic waves, shown schematically by the arrows US in FIG.

The US ultrasonic waves are selected to atomize fluid particles, schematically represented by reference numeral 12, as they enter (arrow A) into the ultrasonic field formed by the generated US ultrasonic waves. Fluid is understood to mean liquid, ice, mist, mist, or a mixture of liquid and dust, or even oil or a solid material. Spraying means reducing or dividing a body into fine p-particles, the body / particles being both liquid and solid. In the present, the atomization of the fluid is therefore the mechanical effect generated on any particle of fluid that enters the ultrasonic field.

The vibration device 9 can be activated with the ignition of the motor vehicle comprising the optical detection system 1. The vibration device 9 can therefore generate the ultrasonic field continuously as the motor vehicle is running. Alternatively, the vibration device 9 may be activated to generate an ultrasonic field intermittently. Finally, it can also be provided that the vibration device 9 is activated when rain is detected, for example by a sensor at the windshield. The transmitter 11 or each transmitter 11 is arranged to generate ultrasonic waves in the field of view of the optical sensor 3, in this example in a direction substantially perpendicular to the optical axis A of the optical sensor 3.

To do this, the transmitter or each transmitter 11 is arranged near the optical sensor 3 and outside the field of view of the optical sensor 3. More precisely, the transmitter or each transmitter 11 is arranged perpendicularly to the optical axis A of the optical sensor 3. The vibratory displacement of a transmitter 11 is represented schematically by the double arrow Δ. The transmitter or each transmitter 11 is decoupled mechanically with respect to the optical sensor 3.

According to the embodiment described, the transmitter 11 or each transmitter 11 comprises at least one piezoelectric transducer 13 made of ceramic material.

Advantageously, the vibration device 9 is able to generate stationary ultrasonic waves. For this purpose, the vibration device 9 comprises for each transmitter 11, a means 11 'associated, which may designate another transmitter 11' or a receiver 1 T, arranged opposite the transmitter 11.

According to an exemplary embodiment, the vibration device 9 may comprise at least two emitters 11, 11 'arranged to generate ultrasound waves which collide forming an ultrasonic standing wave. The emitter 11 'opposite may in particular be similar to the transmitter 11 with which it is associated. The description of the transmitter 11 therefore applies to the opposite transmitter 1T which is therefore not described in more detail.

According to another example, a transmitter 11 and a receiver 11 'associated resonant can be provided.

According to the second embodiment illustrated in FIG. 2, the vibration device 9 comprises a plurality of emitters 11, for example four emitters 11, 1T or two emitters 11 and two associated receivers 1 T.

In the case of several emitters 11, or several pairs of emitters 11, 11 'associated and opposed, or alternatively of several pairs of emitters 11 and associated receivers 11', they are distributed around the field of view of the sensor optical 3.

Moreover, the protective device 5 advantageously comprises a means for evacuating the residues of the particles after atomization.

The protective device 5 may comprise for example at least one nozzle (not shown in the figures) for projecting an air flow F. It is in particular a compressed air flow F. The projection of the air flow F makes it possible to drive away or deflect any fine residual particles p after atomization.

The air flow F is thus projected in front of the optical sensor 3, more precisely in front of the optic 7. In particular, the projection nozzle (not shown) is configured to deliver a flow of air F flush with the optic 7.

In order to form a sort of air curtain shielding the dirt, the air flow F at the outlet of the projection nozzle (not visible) is a laminar air flow. This has the effect of facilitating the deviation of the residual fine particles p after atomization via the laminar air flow F.

As illustrated in FIG. 1, the air flow F is directed in a direction substantially perpendicular to the optical axis A of the optical sensor 3. The projection nozzle (not shown) is therefore disposed on one side of the optical sensor 3 so that the projected air is flush with the optical sensor 3, in particular its convex optics 7.

A heating element may be provided for heating the air flow F. This is particularly advantageous for defrosting or rapid drying of the optics 7 of the optical sensor 3.

In addition, baffles (not shown) may be provided so as to guide this flow of air F.

Thus, a field of view is obtained for the optical sensor 3 which is always clear and clean. Indeed, thanks to the US ultrasound waves emitted, an ultrasound field is created in front of the optic 7, that is to say in the field of view of the optical sensor 3, and this ultrasonic field prevents water, dust or more generally dirt to cross the ultrasonic field in the direction of the optical sensor 3 and to be deposited on the optic 7 of the optical sensor 3. The optical sensor 3 is also protected independently of the speed of movement of the vehicle.

In addition, the protection device 5 according to the invention makes it possible to protect the optical sensor 3 as well when the optical detection system 1 is not working that when the latter is in operation.

Claims (10)

1. Protection device (5) for an optical sensor (3) for a motor vehicle, comprising a vibration device (9) comprising at least one transmitter (11) capable of generating ultrasonic waves, said at least one transmitter (11) ) is adapted to be arranged to generate ultrasonic waves (US) in the field of view of the optical sensor (3), so as to atomize fluid particles (12) as they enter the ultrasonic field formed by the Ultrasonic wave (US) generated characterized in that the device comprises a means of evacuation of residues of the particles after atomization. 2. Protection device (5) according to the preceding claim, wherein the transmitter (11) is intended to be arranged to emit ultrasonic waves in a direction substantially perpendicular to the optical axis (A) of the optical sensor ( 3). 3. Protection device (5) according to any one of the preceding claims, wherein the transmitter (11) is arranged near the optical sensor (3) and out of the field of view of the optical sensor (3). 4. Protection device (5) according to any one of the preceding claims, wherein the transmitter (11) comprises at least one piezoelectric transducer (13) of ceramic material. 5. Protective device (5) according to any one of the preceding claims, wherein the vibration device (9) comprises a plurality of emitters (11) intended to be distributed around the field of view of the optical sensor (3). ). 6. Protection device (5) according to the preceding claim, wherein the vibration device (9) is configured to generate stationary ultrasonic waves, and comprises for each transmitter (11), a transmitter (11 ') opposite or a receiver resonant (11 ') associated. 7. Protection device (5) according to one of the preceding claims, comprising at least one jet of an air flow nozzle (F) in front of the optical sensor (3), the air flow (F) allowing to evacuate the residues of the particles after atomization. 8. Protection device (5) according to the preceding claim, wherein the optical sensor (3) comprises an optical (7) such as a lens, and wherein the projection nozzle is configured to deliver a flow of air ( F) flush with the optics (7), preferably a laminar air flow. 9. optical detection system (1) for a motor vehicle comprising an optical sensor (3) and a protection device (5) of the optical sensor (3) according to any one of the preceding claims. 10. optical detection system (1) according to the preceding claim, wherein said at least one transmitter (11) is mechanically decoupled from the optical sensor (3).