Patent Description:
In the related art, when a vehicle is driving on a rainy day, a lens of a camera disposed outside the vehicle will be subject to raindrops, and thus the imaging of acquired information will be affected. As a result, the image information acquired by the camera lens may be different from the actual information on road and vehicle conditions, and the recognition of traffic signals and obstacles may be inaccurate, causing an automatic driving system of the vehicle to make wrong judgments, which will threaten the safety of passengers and vehicles. Moreover, stains on a surface of the lens will also affect imaging and threaten driving safety.

<CIT> discloses a water droplet removal device of an on-vehicle imaging device, which includes a camera attached to an exterior part of a vehicle; a cover in which a transmission part which transmits light is provided at a position facing a lens; and a motor which rotates the cover. The cover is attached to a case so as to rotate around an optical axis L of the camera by a driving force of the motor. The transmission part inclines relative to the optical axis.

<CIT> relates to a device for protecting an optical sensor for an automotive vehicle that is intended to be attached to the optical sensor, the device includes: a transparent optical element exhibiting rotational symmetry and being rotatably mounted about an axis of rotation, configured to be positioned upstream of the optical sensor so that the axis of rotation of the optical element is merged with the optical axis of the optical sensor; and an actuator that is coupled to the optical element so as to rotate the optical element in order to allow soiling to be removed by a centrifugal effect.

<CIT> provides a water drop removing apparatus for a camera lens assembly, the apparatus is arranged to automatically wipe off water drops or the like attached on the front face of the lens assembly. Injection nozzles consisting of a soft tube in the number of three, for example, are disposed on the top edge and each side edge in such a manner that they are mounted to be rocked around a rocking shaft by a motor or an air rocking mechanism. Each of the injection nozzles are connected with an electromagnetic valve, an air pump, or the like. The three injection valves are rocked fanwise in an order to inject air onto the face of the shooting window through the injection nozzles during the forward period of this rocking, and the nozzles on each side is rocked from top to bottom.

<CIT> is directed to a protection device and the protection device has a transparent disk arranged before an image capturing unit in a moving manner. A water or a soil proofing layer is placed on the disk at an outer side turned away from the image capturing unit. A cleaning device is formed from a wash water-feeding unit, a wash element and a wiper element.

The present invention provides a photographing device for a vehicle. The photographing device can remove raindrops on a lens surface at any time, which results in high imaging definition of a camera and low driving safety hazards.

Any embodiment in the present invention that does not fall within the scope of the present invention should be regarded as an example for understanding the present invention.

For the photographing device according to the embodiments of the present invention, by providing the lens holder which is rotatable relative to the base and on which the transparent lens is mounted, and by providing the driving assembly for driving the lens holder to rotate relative to the base, the lens holder can be driven to rotate using the driving assembly, and the transparent lens can be brought into rotation. During the rotation, a centrifugal force of the transparent lens can hurl out raindrops on the transparent lens, thereby making a surface of the transparent lens maintain a better light transmission effect and improving the reliability of the camera's clear imaging. Moreover, the raindrops on the surface of the transparent lens can be removed at any time during driving to reduce safety hazards during driving.

The features of the present invention will be readily appreciated from the following description.

The accompanying drawings are used for better understanding of the present invention rather than limitation of the present invention.

Reference numerals:
photographing device <NUM> for vehicle, base <NUM>, cylindrical member <NUM>, chamber <NUM>, cover plate <NUM>, camera <NUM>, lens holder <NUM>, first annular groove <NUM>, transparent lens <NUM>, driving assembly <NUM>, motor <NUM>, gear <NUM>, gear ring <NUM>, first compressed gas nozzle <NUM>, blade <NUM>, retaining ring <NUM>, water guiding groove <NUM>, guide seat <NUM>, second annular groove <NUM>.

Exemplary embodiments of the present invention will be illustrated below with reference to the accompanying drawings, which include various details of the embodiments of the present invention to facilitate understanding, and which should be considered to be merely exemplary. Therefore, a person skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope of the present invention defined by the appended claims.

For clarity and conciseness, description about well-known functions and structures will be omitted.

A photographing device for a vehicle according to embodiments of the present invention will be described below with reference to <FIG>.

As shown in <FIG>, the photographing device <NUM> according to the embodiments of the present invention includes a base <NUM>, a camera <NUM>, a lens holder <NUM>, a transparent lens <NUM>, and a driving assembly <NUM>.

As shown in <FIG> and <FIG>, the camera <NUM> is mounted on the base <NUM>; the lens holder <NUM> is mounted on the base <NUM> and is rotatable relative to the base <NUM>; the transparent lens <NUM> is mounted on the lens holder <NUM> and arranged opposite to the camera <NUM>; the driving assembly <NUM> is connected with the lens holder <NUM> to drive the lens holder <NUM> to rotate relative to the base <NUM>. Specifically, as shown in <FIG> and <FIG>, a rear end of the camera <NUM> is connected to the base <NUM>, and the lens holder <NUM> is arranged on a front side of a lens of the camera <NUM>, so that the camera <NUM> can perform clear imaging through the transparent lens <NUM> mounted on the lens holder <NUM>.

Therefore, according to the technical solution of the embodiments of the present invention, by providing the lens holder which is rotatable relative to the base and on which the transparent lens is mounted, and by providing the driving assembly for driving the lens holder to rotate relative to the base, the lens holder can be driven to rotate using the driving assembly, and the transparent lens can be brought into rotation. During the rotation, a centrifugal force of the transparent lens can hurl out raindrops on the transparent lens, thereby making a surface of the transparent lens maintain a better light transmission effect and improving the reliability of the camera's clear imaging. Moreover, the raindrops on the surface of the transparent lens can be removed at any time during driving to reduce safety hazards during driving.

In some embodiments, as shown in <FIG>, the base <NUM> includes a cylindrical member <NUM> and a cover plate <NUM>. The cylindrical member <NUM> has a chamber <NUM>, and a first end (a front end as shown in <FIG>) of the cylindrical member <NUM> is opened to make a first end of the chamber <NUM> open. The cover plate <NUM> is arranged at a second end (a rear end as shown in <FIG>) of the cylindrical member <NUM> to cover a second end of the chamber <NUM>. The camera <NUM> is mounted on the cover plate <NUM> and located in the chamber <NUM>. The lens holder <NUM> is mounted at the first end of the cylindrical member <NUM> to cover, together with the transparent lens <NUM>, the first end of the chamber <NUM>.

Specifically, as shown in <FIG>, the cylindrical member <NUM> extends in a front-rear direction, a rear end of the chamber <NUM> of the cylindrical member <NUM> is open, and the rear end of the cylindrical member <NUM> is provided with the cover plate <NUM> to cover the rear end of the chamber <NUM>. Preferably, the cylindrical member <NUM> and the cover plate <NUM> are integrally formed, that is, the base <NUM> is an integrally formed member. It should be noted that the cylindrical member <NUM> and the cover plate <NUM> may also be two separate structural members. After the cylindrical member <NUM> and the cover plate <NUM> are formed separately, the cover plate <NUM> is connected to the rear end of the cylindrical member <NUM> to form the base <NUM>.

A front end of the chamber <NUM> of the cylindrical member <NUM> is open, and the lens holder <NUM> is mounted at the front end (the first end) of the cylindrical member <NUM> and provided with a through hole that runs through the lens holder <NUM> in the front-rear direction. The transparent lens <NUM> is mounted in the through hole and opposite to the camera <NUM> in the front-rear direction. The lens holder <NUM> and the transparent lens <NUM> together shield the front end of the chamber <NUM>. Therefore, a relatively sealed space (chamber) can be formed by the cover plate, the cylindrical member, the lens holder, and the transparent lens, and external water vapor or dust can be prevented from invading the chamber, which is beneficial for clear imaging of the camera in the chamber and enhances the damage resistance.

In some embodiments, as shown in <FIG>, the photographing device <NUM> further includes a retaining ring <NUM>. The retaining ring <NUM> is arranged at the first end of the cylindrical member <NUM>, and a part of the lens holder <NUM> is clamped between the retaining ring <NUM> and the first end of the cylindrical member <NUM>. Therefore, the clamping by the retaining ring and the cylindrical member can be used to prevent the lens holder from moving in the front-rear direction, and the assembling reliability of the transparent lens can be improved. In the embodiment shown in <FIG>, the retaining ring <NUM> is a circular ring. It can be understood that the shape of the retaining ring <NUM> is not limited to that shown in <FIG>, and instead, the retaining ring <NUM> can be provided suitably according to the opening shape of the cylindrical member <NUM>.

In some embodiments, as shown in <FIG>, the retaining ring <NUM> is provided with a water guiding groove <NUM> that has a length extending along a peripheral direction of the retaining ring <NUM>, a width extending along a radial direction of the retaining ring <NUM>, and a depth extending along an axial direction of the retaining ring <NUM>. In other words, the water guiding groove <NUM> is a groove extending along the peripheral direction of the retaining ring <NUM> and having a certain depth in the axial direction of the retaining ring <NUM>, so that the water guiding groove can be used to drain the raindrops hurled out by the transparent lens to the outside of the photographing device.

Specifically, as shown in <FIG>, <FIG>, <FIG>, the water guiding groove <NUM> extends along the peripheral direction of the retaining ring <NUM> to form the length of the water guiding groove <NUM>. The water guiding groove <NUM> extends forward from a rear end surface of the retaining ring <NUM> to form the depth of the water guiding groove <NUM> and extends inward from an outer peripheral surface of the retaining ring <NUM> to form the width of the water guiding groove <NUM>.

Further, as shown in <FIG>, there are a plurality of water guiding grooves <NUM>, and the plurality of water guiding grooves <NUM> are arranged at intervals along the peripheral direction of the retaining ring <NUM>. Thus, the efficiency and reliability of guiding water by the water guiding groove can be improved.

In some embodiments, as shown in <FIG>, the driving assembly <NUM> includes a motor <NUM>, a gear <NUM>, and a gear ring <NUM>. The motor <NUM> is mounted on the cover plate <NUM> and located outside the chamber <NUM>. The gear <NUM> is located in the chamber <NUM> and connected to an output shaft of the motor <NUM>. The gear ring <NUM> is mounted on the lens holder <NUM> and arranged in the chamber <NUM>, and the gear ring <NUM> meshes with the gear <NUM>. Specifically, a front end of the motor <NUM> is mounted to a rear end surface of the cover plate <NUM>. The output shaft of the motor <NUM> extends forward into the chamber <NUM>, and the gear <NUM> is connected to a front end of the output shaft. The gear ring <NUM> extends along a peripheral direction of the lens holder <NUM> and arranged on a rear side of the lens holder <NUM>.

The output shaft of the motor can drive the gear to rotate, and the engagement between the gear and the gear ring can drive the gear ring <NUM> to rotate. In turn, the rotation of the gear ring can drive the lens holder to rotate, so that the transparent lens rotates along with the lens holder to hurl out the raindrops on the surface of the transparent lens.

In addition, in the embodiment shown in <FIG>, the base <NUM>, the lens holder <NUM>, the retaining ring <NUM>, and the gear <NUM> can be made of engineering plastics with self-lubricity, abrasion resistance, and good mechanical properties, so as to reduce the abrasion of components and parts of the photography device during the rotation of the lens holder. The transparent lens <NUM> may be spherical, which can facilitate the hurl-out of raindrops.

It can be understood that the driving assembly <NUM> is not limited to the embodiments shown in <FIG>. For example, in other embodiments, as shown in <FIG>, the driving assembly <NUM> includes a first compressed gas nozzle <NUM> and a plurality of blades <NUM> mounted on the lens holder <NUM>. The first compressed gas nozzle <NUM> and the blades <NUM> are arranged in the chamber <NUM>. The first compressed gas nozzle <NUM> can eject compressed gas to the blades <NUM> to drive the blades <NUM> to rotate. As a result, the compressed gas ejected by the first compressed gas nozzle can be used as power to drive the blades to rotate, and in turn the blades are used to drive the lens holder to rotate, so that the transparent lens can rotate and hurl out raindrops. In addition, the compressed gas ejected by the first compressed gas nozzle can also remove mist in the chamber and improve the imaging clarity of the camera.

In an embodiment shown in <FIG>, the base <NUM>, the lens holder <NUM>, and the retaining ring <NUM> can be made of engineering plastics with self-lubrication, abrasion resistance, and good mechanical properties, to reduce the wear and tear of parts of the photographing device when the lens holder rotates.

The structures of the base <NUM> and the transparent lens <NUM> are not limited to the embodiments shown in <FIG>. For example, in other embodiments, as shown in <FIG>, the transparent lens <NUM> is substantially cylindrical, the lens holder <NUM> is provided with a first annular groove <NUM>, a first end of the transparent lens <NUM> is fitted in the first annular groove <NUM>, and the base <NUM> is arranged in the transparent lens <NUM>. Specifically, as shown in <FIG>, the transparent lens <NUM> is a cylindrical structural member extending in a left-right direction (i.e., the left-right direction as shown in <FIG>), and the camera <NUM> is mounted on the base <NUM>. The substantially cylindrical transparent lens has a large light transmission range and high light transmission intensity, which is conducive to the clear imaging of the camera. The lens holder <NUM> is mounted at a right end of the transparent lens <NUM>, the first annular groove <NUM> extends along the peripheral direction of the lens holder <NUM> and is opened leftwards, and the right end of the transparent lens <NUM> can be inserted into the first annular groove <NUM>, thereby improving the convenience of assembling the lens holder and the transparent lens.

In some specific embodiments, as shown in <FIG> and <FIG>, the photographing device <NUM> further includes a guide seat <NUM> connected to the base <NUM> and arranged opposite to the lens holder <NUM>. The guide seat <NUM> is provided with a second annular groove <NUM>, and a second end of the transparent lens <NUM> is fitted in the second annular groove <NUM>. Specifically, the guide seat <NUM> is disposed at a left end (i.e., the second end) of the transparent lens <NUM>, the guide seat <NUM> is mounted on the base <NUM>, the second annular groove <NUM> extends in a peripheral direction of the guide seat <NUM> and is opened rightwards, and the left end of the transparent lens <NUM> is suitable to be inserted into the second annular groove <NUM>.

Therefore, the way of assembling the guide seat and the transparent lens can be simplified, the rotation of the transparent lens can be guided by the second annular groove, and the guide seat, the transparent lens, and the lens holder can constitute a closed receiving space to protect the camera in the transparent lens from being corroded by moisture and dust.

In some specific embodiments, as shown in <FIG>, the lens holder <NUM> and the guide seat <NUM> are both substantially cylindrical, which facilitates the adaptation to the substantially cylindrical transparent lens <NUM>. The driving assembly <NUM> includes the motor <NUM>, the output shaft of the motor <NUM> is connected to the lens holder <NUM>, and the motor <NUM> is suitable to drive the lens holder <NUM> to rotate. In turn, the lens holder <NUM> can drive the transparent lens <NUM> to rotate to hurl out raindrops on the surface of the transparent lens <NUM>.

In the embodiment shown in <FIG>, the base <NUM>, the lens holder <NUM>, and the lens guide seat <NUM> can be made of engineering plastics with self-lubrication, abrasion resistance, and good mechanical properties, to reduce the wear and tear of parts of the photographing device when the lens holder rotates.

In some embodiments, the photographing device <NUM> further includes a second compressed gas nozzle (not shown) that can eject compressed gas toward the transparent lens <NUM> from the outside of the transparent lens <NUM>. Therefore, the compressed gas ejected from the second compressed gas nozzle can be used to blow away stains on an outer surface of the transparent lens, which is further conducive to the clear imaging of the camera.

In some embodiments, the photographing device <NUM> further includes a third compressed gas nozzle (not shown) that can eject compressed gas toward the transparent lens from the inside of the transparent lens. Therefore, the compressed gas ejected from the third compressed gas nozzle can be used to remove the mist within the photographing device, and further improve the imaging clarity. In the embodiment shown in <FIG>, the third compressed gas nozzle may not be provided, and a defogging effect can be achieved when the first compressed gas nozzle <NUM> drives the blades <NUM> to rotate.

In some specific embodiments, the photographing device <NUM> further includes a heating component (not shown) that can be used to heat the compressed gas in the third compressed gas nozzle to defrost and avoid condensation on the surface of the transparent lens.

In some embodiments, the photographing device <NUM> further includes a cleaning liquid nozzle (not shown) that can spray a cleaning liquid to the transparent lens <NUM> from the outside of the transparent lens <NUM>. Therefore, the cleaning liquid can be used to remove stains on the outer surface of the transparent lens and make the camera imaging clearer.

In some embodiments, the photographing device <NUM> further includes a wiper assembly (not shown) that can cooperate with the cleaning liquid nozzle to remove stains on the surface of the transparent lens <NUM>. It can be understood that the wiper assembly can make the cleaning liquid evenly spread on the surface of the transparent lens and can wipe back and forth on the surface of the transparent lens to improve a cleaning effect of the cleaning liquid.

A photographing device for a vehicle according to a specific example of the present invention will be described below with reference to <FIG> and <FIG>.

As shown in <FIG>, <FIG> and <FIG>, the photographing device <NUM> includes a base <NUM>, a camera <NUM>, a lens holder <NUM>, a transparent lens <NUM>, and a driving assembly <NUM>. As shown in <FIG>, the base <NUM> includes a cylindrical member <NUM> extending in a front-rear direction (e.g., the front-rear direction shown in <FIG>) and having a chamber <NUM>. A rear end of the chamber <NUM> of the cylindrical member <NUM> is open, and a cover plate <NUM> is provided at a rear end of the cylindrical member <NUM> to cover the rear end of the chamber <NUM>.

A front end of the chamber <NUM> of the cylindrical member <NUM> is open, and the lens holder <NUM> is mounted at a front end of the cylindrical member <NUM>. The lens holder <NUM> is provided with a through hole that runs through the lens holder <NUM> in the front-rear direction. The transparent lens <NUM> is mounted in the through hole and opposite to the camera <NUM> in the front-rear direction. The lens holder <NUM> and the transparent lens <NUM> together shield the front end of the chamber <NUM>.

As shown in <FIG>, the photographing device <NUM> includes an annular retaining ring <NUM> mounted at the front end of the cylindrical member <NUM> and located on a front side of the lens holder <NUM>, and an edge of the lens holder <NUM> is sandwiched between the annular retaining ring <NUM> and the front end of the cylindrical member <NUM>. As shown in <FIG>, the annular retaining ring <NUM> is provided with a water guiding groove <NUM> that extends along a peripheral direction of the retaining ring <NUM> and has a certain width in a radial direction of the retaining ring <NUM> and a certain depth in a front-rear direction of the retaining ring <NUM>. There are a plurality of water guiding grooves <NUM> evenly spaced along the peripheral direction of the retaining ring <NUM>.

As shown in <FIG>, the driving assembly <NUM> includes a motor <NUM>, a gear <NUM>, and a gear ring <NUM>. A front end of the motor <NUM> is mounted to a rear end surface of the cover plate <NUM>. An output shaft of the motor <NUM> extends forward into the chamber <NUM>. The gear <NUM> and the gear ring <NUM> are both located in the chamber <NUM>. The gear <NUM> is connected to a front end of the output shaft. The gear ring <NUM> extends in a peripheral direction of the lens holder <NUM> and is arranged on a rear side of the lens holder <NUM>. The gear <NUM> meshes with the gear ring <NUM>.

A photographing device for a vehicle according to another embodiment of the present invention will be described below with reference to <FIG>.

As shown in <FIG>, the photographing device <NUM> includes a base <NUM>, a camera <NUM>, a lens holder <NUM>, a transparent lens <NUM>, blades <NUM>, and a first compressed gas nozzle <NUM>.

As shown in <FIG>, the blades <NUM> are located in the chamber <NUM>, and the blades <NUM> are distributed along a peripheral direction of the lens holder <NUM> and arranged on a rear side of the lens holder <NUM>. The first compressed gas nozzle <NUM> passes through and is connected to the cover plate <NUM>. A front end of the first compressed gas nozzle <NUM> is located in the chamber <NUM>, and a rear end of the first compressed gas nozzle <NUM> extends out of the chamber <NUM>, that is, the rear end of the first compressed gas nozzle <NUM> is located outside the base <NUM>, to facilitate the docking with external ventilation equipment. The front end of the first compressed gas nozzle <NUM> has a jet orifice that is opened toward the blades <NUM>.

Other structures and operations of the photographing device shown in <FIG> may be the same as those in the embodiments shown in <FIG> and will not be described in detail here.

A photographing device <NUM> for a vehicle according to another embodiment of the present invention will be described below with reference to <FIG>.

As shown in <FIG>, the photographing device <NUM> includes a base <NUM>, a camera <NUM>, a lens holder <NUM>, a transparent lens <NUM>, and a lens guide seat <NUM>. As shown in <FIG>, the transparent lens <NUM> is a cylindrical structural member extending in a left-right direction (e.g. the left-right direction as shown in <FIG>), a right end of the transparent lens <NUM> is also open, and the guide seat <NUM> is mounted at the right end of the transparent lens <NUM> to block the open right end. A left end of the transparent lens <NUM> is open, and the lens holder <NUM> is mounted at the left end of the transparent lens <NUM> to block the open left end. The base <NUM> is arranged in the transparent lens <NUM>, and a right end of the base <NUM> is connected with the guide base <NUM>. The camera <NUM> is mounted on the base <NUM>.

As shown in <FIG>, the photographing device <NUM> includes a motor <NUM> located in the transparent lens <NUM> and mounted on the base <NUM>, and an output shaft of the motor <NUM> is connected to the lens holder <NUM>.

As shown in <FIG> and <FIG>, the lens holder <NUM> is provided with a first annular groove <NUM> that extends along a peripheral direction of the lens holder <NUM>. The first annular groove <NUM> is opened rightwards, and the left end of the transparent lens <NUM> is inserted into the first annular groove <NUM>.

As shown in <FIG> and <FIG>, the guide seat <NUM> is provided with a second annular groove <NUM> that extends in a peripheral direction of the guide seat <NUM>. The second annular groove <NUM> is opened leftwards, and the right end of the transparent lens <NUM> is suitable to be inserted into the second annular groove <NUM>.

In the description of the present invention, it should be understood that terms such as "front," "rear," "inner," "outer," "axial," "radial," "circumferential" and the like should be constructed to refer to the orientation or position as then described or as shown in the drawings under discussion. These terms are for convenience and simplification of description and do not indicate or imply that the device or element referred to must have a particular orientation, or be constructed and operated in a particular orientation, so these terms shall not be construed to limit the present invention.

In addition, terms such as "first" and "second" are used herein for purposes of description and are not intended to indicate or imply relative importance or significance or to imply the number of indicated technical features. Thus, the feature defined with "first" and "second" may comprise one or more of this feature. In the description of the present invention, the term "a plurality of" means at least two, such as two or three, unless specified otherwise.

In the present invention, unless specified or limited otherwise, the terms "mounted," "connected," "coupled," "fixed" and the like are used broadly, and may be, for example, fixed connections, detachable connections, or integral connections; may also be mechanical or electrical connections; may also be direct connections or indirect connections via intervening structures; may also be inner communications of two elements, which can be understood by those skilled in the art according to specific situations.

In the present invention, unless specified or limited otherwise, a structure in which a first feature is "on" or "below" a second feature may include an embodiment in which the first feature is in direct contact with the second feature, and may also include an embodiment in which the first feature and the second feature are not in direct contact with each other, but are contacted via an additional feature formed therebetween. Furthermore, a first feature "on," "above," or "on top of" a second feature may include an embodiment in which the first feature is right or obliquely "on," "above," or "on top of" the second feature, or just means that the first feature is at a height higher than that of the second feature; while a first feature "below," "under," or "on bottom of" a second feature may include an embodiment in which the first feature is right or obliquely "below," "under," or "on bottom of" the second feature, or just means that the first feature is at a height lower than that of the second feature.

Claim 1:
A photographing device (<NUM>) for a vehicle, comprising:
a base (<NUM>);
a camera (<NUM>) mounted on the base (<NUM>);
a lens holder (<NUM>) mounted on the base (<NUM>) and rotatable relative to the base (<NUM>);
a transparent lens (<NUM>) mounted on the lens holder (<NUM>) and arranged opposite to the camera (<NUM>); and
a driving assembly (<NUM>) connected with the lens holder (<NUM>) to drive the lens holder (<NUM>) to rotate relative to the base (<NUM>);
a retaining ring (<NUM>);
wherein the base (<NUM>) comprises a cylindrical member (<NUM>) and a cover plate (<NUM>); the cylindrical member (<NUM>) has a chamber (<NUM>), a first end of the cylindrical member (<NUM>) is opened to make a first end of the chamber (<NUM>) open, and the cover plate (<NUM>) is arranged at a second end of the cylindrical member (<NUM>) to cover a second end of the chamber (<NUM>); the camera (<NUM>) is mounted on the cover plate (<NUM>) and located in the chamber (<NUM>); the lens holder (<NUM>) is mounted at the first end of the cylindrical member (<NUM>) to cover, together with the transparent lens (<NUM>), the first end of the chamber (<NUM>);
wherein the retaining ring (<NUM>) is arranged at the first end of the cylindrical member (<NUM>), a part of the lens holder (<NUM>) is clamped between the retaining ring (<NUM>) and the first end of the cylindrical member (<NUM>);
characterized in that: the retaining ring (<NUM>) is provided with a water guiding groove (<NUM>), the water guiding groove (<NUM>) extends along a peripheral direction of the retaining ring (<NUM>) to form a length of the water guiding groove (<NUM>), and the water guiding groove (<NUM>) extends forward from a rear end surface of the retaining ring (<NUM>) to form a depth of the water guiding groove (<NUM>) and extends inward from an outer peripheral surface of the retaining ring (<NUM>) to form a width of the water guiding groove (<NUM>).