Protection system for a camera

Abstract

The present invention relates to a system for protecting a lens (250) of a camera (400) against a spray of solid and liquid particles, comprising a fan (300) which produces a flow of air conveyed towards the lens (250) by means of a conveying duct (110), characterised in that: - the fan (300) is a centrifugal fan, - the system comprises a hollow integrated fluidic box (1) surrounded by a continuous sealed casing defining: • a volute (100) surrounding the turbine of the fan (300), • a chamber (200) • a conveying duct (110) consisting of a hollow volume connecting the volute (100) to the chamber (200), - the chamber (200) opening at the periphery of the lens (250) by means of at least one annular opening (130) in order to generate a flow of air towards the optical field of the lens, and the chamber (200) also surrounding at least part of the body of the camera (400).

Description

Camera protection system Scope of the invention

[0001] The present invention relates to the protection of a camera lens against dirt or rain, which can impair vision. It is particularly relevant to cameras used for safety functions on autonomous vehicles, for example, where perfect vision must be automatically ensured to guarantee the quality of information acquired about the vehicle's environment. These cameras are exposed to inclement weather and occasional disturbances such as rain, splashes, and insects, which can impact the lens and disrupt image acquisition.

[0002] Solutions have been developed that involve blowing air in front of the lens to expel incident particles. State of the art

[0003] For example, prior art includes US patent 9217864B2 describing an automatic camera lens cleaning system, comprising a blower assembly having a housing adapted to contain a camera lens externally and an annular element disposed around the camera lens, as well as a plurality of openings arranged along a perimeter of the annular element. This plurality of openings communicates with an internal volume of the housing, which in turn communicates with an elongated tube connected to an air compressor pump that can be operated by a central processing unit. The air compressor pump is adapted to force air through the tube so that the air exits through the plurality of openings in the annular element.

[0004] Patent application WO2018130610A1 relates to a camera device for a motor vehicle comprising a camera for detecting an environmental area of ​​the motor vehicle, the camera having at least one lens, comprising a retaining device for retaining the camera on the motor vehicle, and comprising a cleaning device for cleaning an external surface of the lens device, the cleaning device comprising a fan element which is disposed on the retaining device and which is designed to provide an airflow to clean the external surface of the lens device.

[0005] Patent application WO2018161518A1 relates to the field of surveillance cameras that are automatically cleaned.

[0006] Patent KR100189288B presents another example of a camera housed in a casing having a fan in its rear part and an opening in its front part blowing air in an axial direction. Disadvantages of prior art

[0007] Prior art solutions are not entirely satisfactory because they involve significant bulk: the cleaning system's volume is sized to accommodate the camera within the airflow, necessitating a housing considerably larger than the camera itself. For autonomous vehicle applications, cameras are housed in confined spaces, such as rearview mirrors, side pillars, front bumpers, and trunks, which are incompatible with prior art solutions.

[0008] Other prior art solutions involve supplying the annular chamber via a pipe carrying pressurized air from a pressurized air reservoir. These solutions require a complex fluidic piping system, which is prone to failures and malfunctions and difficult to install in a vehicle. Furthermore, these solutions result in significant pressure losses. Solution provided by the invention

[0009] To overcome this drawback, the present invention relates to a system for protecting a camera lens against the projection of solid and liquid particles, comprising a fan producing an airflow transmitted towards said lens via a delivery duct. The fan is centrifugal in type, and the system comprises an integrated hollow fluidic box surrounded by a continuous sealed casing defining a volute surrounding the turbine of said fan, a chamber, and a delivery duct consisting of a hollow volume connecting said volute to said chamber. This chamber opens at the periphery of said lens through at least one annular opening to generate an airflow in the direction of the lens's optical field, said chamber also surrounding at least a portion of the camera body.

[0010] In particular, it concerns a cleaning system having all or some of the following characteristics: the intake duct divides into two branches, one branch connecting the fan outlet to the chamber inlet and the other branch connecting the fan outlet to the inlet of a second chamber surrounding a second lens of a second camera; these branches also forming an extension of said fan and / or said second chamber. The fan's air inlet opens into a volume containing the stator of an electric motor driving the fan. The airflow at the fan inlet can cool the motor stator. To cool the camera, the airflow at the chamber level will be used instead. The front edge of the chamber is behind the transverse plane passing through the apex of the lens. The annular aperture has a tubular cross-section upstream of a transverse plane and a diverging portion downstream of this plane.The annular aperture has a peripheral lip defining its outer surface, said peripheral lip having a flared outer wall, with a substantially cylindrical base extending into a diverging downstream portion. The opening, α, of the diverging downstream portion is between 30° and 120°. The annular aperture has, for its inner wall, a cylindrical surface, formed either by the peripheral surface of the camera lens or by a ring surrounding the camera lens to define a precise geometry. The cylindrical surface extending to a transverse plane and downstream of the transverse plane, the annular aperture is defined for its inner wall by a sharply diverging surface, formed either by the peripheral surface of the camera lens or by a ring surrounding the camera lens to define a precise geometry.The lens protection system includes a means for controlling the motor of said fan according to the speed of movement of a vehicle equipped with said system and / or a rain detector and / or a means for processing images acquired by said camera to characterize dirt in the optical field of said camera.

[0011] Detailed description of a non-limiting example of implementation

[0012] The present invention will be better understood upon reading the following description, concerning a non-limiting example of an embodiment illustrated by the accompanying drawings where:

[0013] The figure represents a top-down perspective view of a first example of an embodiment of a system according to the invention.

[0014] Figure 1 represents a side perspective view of a second embodiment of a system according to the invention with two cameras,

[0015] Figure 1 represents a top-down perspective view of a second embodiment of a system according to the invention with two cameras,

[0016] Lare represents a cross-sectional view of the fluidic box of the second example of an embodiment of a system according to the invention,

[0017] This represents a detailed cross-sectional view of the fluidic channel at the level of a camera.

[0018] The diagram represents a schematic representation of the fluid flow around the lens of a camera. General principle

[0019] The general principle of the invention consists of implementing the cleaning system in the form of an integrated system comprising an integrated fluidic box (1) forming a plastic fluidic component integrating, in the same component, three complementary functional parts, namely: a volute (100) channeling the airflow produced by a centrifugal fan (300), a chamber (200) surrounding the lens (250) and possibly a part of the camera body (400), this chamber (200) opening at the periphery of said lens (250) by at least one opening to generate an airflow in the direction of the optical field of the lens (250), and a conduit (110) for conveying the airflow between the volute (100) and the chamber (200).

[0020] This results in an integrated assembly that reduces pressure losses and has a very small footprint, allowing it to be housed as close as possible to the camera (400), around the lens (250). This integrated fluidic box (1) can be made by welding together thermoformed or molded parts to form a sealed enclosure into which the centrifugal fan (300) and the camera (400) are inserted. As will be explained later, this integrated fluidic box (1) can also have multiple chambers (200) for cleaning the lenses of several cameras, with a single volute (100) and a single conveying duct (110) common to several toroidal chambers (200).

[0021] The airflow generated in the direction of the lens's optical field (250) is defined as an airflow described by a vector field whose principal direction is along the lens's optical axis.

[0022] In the patent, the term "upstream" refers, for an element located in the path of the airflow, to the portion traversed by that airflow before reaching that element. The term "downstream" refers to the portion traversed by that airflow after that element.

[0023] Detailed description of a non-limiting example of implementation

[0024] Laillustre an example of the implementation of a camera cleaning system in top view.

[0025] The fluidic box (1) is formed by a hollow plastic component defining, with a single enveloping skin: a volute (100) in which is inserted a centrifugal fan module (300) a conveying conduit (110) a chamber (200).

[0026] The volute (100) has a spiral shape to receive a turbine that draws in air axially and expels the air centrifugally into the volume defined by the volute (100). The air produced in the volute (100) opens into a segment of the fluidic box (1) forming a delivery duct (110) extending into a branch (120) opening into a chamber (200).

[0027] The chamber (200) surrounds the lens (250) of a camera (400). It terminates downstream with a non-visible annular opening to produce an airflow around the periphery of the lens (250). This chamber (200) can partially surround the body of the camera (400), thus providing some cooling, improving the mechanical connection between these two elements, or enhancing the sealing of the fluidic chamber.

[0028] Detailed description of a second example of implementation

[0029] Figures 2 and 3 illustrate an example of the implementation of a cleaning system for two cameras, respectively in side and top perspective view.

[0030] This embodiment differs from the previous embodiment in that the fluidic box (1) has two chambers (200), the conveying conduit (110) dividing into two branches (120, 125) each opening into one of said chambers (200).

[0031] Each of these chambers (200) surrounds the lens (250) of a camera (400). It terminates downstream with an annular opening (130) to produce an airflow over the periphery of the lens (250). Detailed description of the room

[0032] Figures 5 represent a detailed view of the chamber (200). It communicates with the conveying conduit (100) via a connection zone (115) sized to avoid any pressure loss.

[0033] The downstream wall of the chamber (200) has an annular opening (130) whose section is slightly larger than the section of the lens (250), so as to preserve a peripheral slit around this lens (250).

[0034] The edge of this annular opening (130) is bordered by a peripheral lip (131) ensuring the deflection of the air jet, so as to produce a jet in the shape of a torch, or flame, coaxial with the optical axis (255) of the lens (250), or possibly oriented angularly with respect to this optical axis (255).

[0035] To obtain a torch-shaped airflow, the annular opening has an upstream part that is preferably tubular in shape and a downstream part that is divergent, that is to say, has an increase in its cross-section.

[0036] An example of the embodiment of the peripheral lip (131) is illustrated in Figure 1. It has a flared outer wall, with a substantially cylindrical base extending into a diverging downstream portion (132). This diverging downstream portion (132) has an edge (133). The opening angle, α, of the diverging downstream portion (132) is between 30° and 120°. This edge (133) guides the flow to its outlet and, through a wall effect known as the Coanda effect, flares the flow. The opening angle, α, is a parameter that the designer can choose to flare the airflow (the air jet) more or less.

[0037] The annular aperture (130) is also defined, for its inner wall (260), by a cylindrical surface (261), formed either by the peripheral surface of the camera lens or by a ring surrounding the camera lens to define a precise geometry. The cylindrical surface (261) extends to a transverse plane (265) passing through the inflection zone between the upstream tubular portion and the downstream diverging portion. The cylindrical surface terminates in a transverse edge (262). Downstream of the transverse plane (265), the annular aperture (130) is defined, for its inner wall, by a diverging surface (263), formed either by the peripheral surface of the camera lens (250) or by a ring surrounding the camera lens to define a precise geometry.

[0038] The width of the annular opening (130), at the level of the downstream tubular part, is between 0.3 and 2 millimeters.

[0039] Depending on the contexts of use of the invention, the peripheral lip (131) or the inner wall (261) may have an asymmetrical geometry.

[0040] The operation of the fan motor is optionally controlled based on parameters such as the speed of the vehicle equipped with the cleaning system or characteristics of the image captured by the camera or meteorological information.

[0041] As shown in Figure 1, the edge (262) creates an abrupt discontinuity in the airflow, preventing the Coanda effect of the airflow attaching to the lens wall (250). The flow near the inner wall (260) thus continues its path along the optical axis, which allows the total airflow to spread out and provides increased protection for the lens by increasing the size of the particle deflection zone.

[0042] As illustrated in 6, the divergent surface (263) of the inner wall (260) can be continuously divergent, or present a zone without divergence, the breaking of the Coanda effect being caused by the abrupt discontinuity of the inner wall (260) at the level of the transverse plane (265).

[0043] The example of a two-camera implementation is only for illustrative purposes and in no way limits the invention; it is entirely possible to retain the benefit of compactness when the ventilation system is associated with only one camera.

[0044] In some cases it is also advantageous to increase the number of cameras nearby and the invention can be further developed by adapting the ventilation system to the required flow rate depending on the number of cameras to be protected.

[0045] In a non-exhaustive manner, it is possible to use the airflow generated by the ventilation system to cool components integrated in the immediate environment.

[0046] It is also possible to use the heat dissipated by the components being cooled, or by the fan, or to generate heat using a resistive device integrated into the system, to increase the temperature of the airflow generated at the cameras. This allows, for example, for the removal of condensation from the lens during startup, or for melting ice accumulated in cold weather. More specifically, it is possible to integrate an air mixer between a flow directly from the ventilation system and another flow diverted through a heating system, thus providing precise control over the temperature of the air generated at the cameras.Also, when multiple cameras are protected by the device, the airflow delivered to each camera can be adjusted, either passively by sizing the individual ducts, or actively by using a controlled shutter mechanism. This is particularly useful when the orientation or position of the cameras results in different airflow energy requirements for their protection.

[0047] The present invention consists of generating an airflow primarily directed along the optical axis (255) of the lens (250) with a magnitude greater than its tangential component. The preferred airflow shape is that of a flame, which has an axisymmetric geometry, but it is entirely possible, by modifying the geometry of the annular aperture, to generate a flow inclined with respect to the optical axis (255) or even to generate a non-axisymmetric airflow to promote the deflection of particles in a specific direction.

[0048] In addition, the invention also provides for adapting the flow rate of the air generated by the fan, according to contextual parameters, such as the speed of the vehicle, rain detection, detection of the approach of another vehicle, outside temperature, detection of the nature of the weather, rain, snow, hail, fog, mist, or even the size of the particles to be deflected.

[0049] Finally, preferably the fan's air intake is directed towards a protected part of the environment, which avoids drawing in air laden with water particles, or drawing in stagnant water from a nearby pocket.

Claims

A system for protecting a camera lens (250) (400) against projections of solid and liquid particles, comprising a fan (300) producing an airflow transmitted towards said lens (250) via a conveying duct (110), characterized in that said fan (300) is of the centrifugal type; said system comprises an integrated hollow fluidic box (1) surrounded by a continuous sealed casing defining: a volute (100) surrounding the turbine of said fan (300), a chamber (200), a conveying duct (110) consisting of a hollow volume connecting said volute (100) to said chamber (200), said chamber (200) opening at the periphery of said lens (250) by at least one annular opening (130) to generate an airflow in the direction of the optical field of the lens, said chamber (200) also surrounding at least a part of the body of said camera (400). Lens protection system according to claim 1 characterized in that the conveying conduit (110) is divided into two branches (120, 125), one branch (120) connecting the outlet of the fan (300) to the inlet of the chamber (200) and the other branch (125) connecting the outlet of the fan (300) to the inlet of a second chamber surrounding a second lens (250) of a second camera (400), said branches (120, 125) also constituting an extension of said fan (300) and / or of said second chamber (200). Lens protection system (250) according to claim 1 or 2 characterized in that the air inlet of the fan (300) opens into a volume containing the stator of an electric motor driving the fan. Lens protection system (250) according to claim 1 characterized in that the front edge of the chamber (200) is behind the transverse plane passing through the top of the lens. Lens protection system (250) according to claim 1 characterized in that the annular opening (130) has a tubular section upstream of a transverse plane (265) and a diverging part downstream of this plane. Lens protection system (250) according to the preceding claim characterized in that the annular opening (130) has a peripheral lip (131) defining its outer surface, said peripheral lip (131) having a flared outer wall, with a substantially cylindrical base extending with a diverging downstream part (132). Lens protection system (250) according to the preceding claim characterized in that the opening, α, of the downstream diverging part (132) is between 30° and 120°. Lens protection system (250) according to claim 5 characterized in that the annular opening (130) has for its inner wall (260), a cylindrical surface (261), constituted either by the peripheral surface of the camera lens, or by a ring surrounding the camera lens to define a precise geometry. Lens protection system (250) according to the preceding claim characterized in that the cylindrical surface (261) extending to a transverse plane (265) and downstream of the transverse plane (265), the annular opening (130) is defined for its inner wall by a sharply diverging surface (263), constituted either by the peripheral surface of the camera lens (250), or by a ring surrounding the camera lens to define a precise geometry. Lens protection system according to claim 1 characterized in that it comprises a means for controlling the motor of said fan as a function of the speed of movement of a vehicle equipped with said system and / or a rain detector and / or a means for processing images acquired by said camera to characterize dirt in the optical field of said camera.

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