Patent Description:
An imaging system for a motor is known for example from the <CIT>, wherein the imaging system comprises a camera mounting part and at least one camera module to be mounted to said camera mounting part. The camera module comprises a lens objective, a lens holder holding said lens objective, an image sensor and a back plate holding said image sensor. The camera module is attached by rotation locking means.

Another imaging system for a motor vehicle is known for example from the <CIT>, with a camera mounting part and a camera module mounted to said camera mounting part. The camera module is provided with a radially outwardly directed protrusion and a retainer ring, wherein the retainer ring comprises a first ring element made from a rigid material and a second ring element made from a flexible material. The retainer ring is attached by pushing it over the protrusion under elastic deformation of the second ring element made from the flexible material to an attachment position, wherein the camera module is attached to the camera mounting part by being clamped to the camera mounting part when the retainer ring is in the attachment position.

<CIT> discloses a camera for a motor vehicle with a housing configured to shield electromagnetic radiation.

With respect to the prior art, it is the object of this invention to provide an imaging system in which the attachment of a camera module to a camera mounting part is further improved.

The invention solves the problem with the subject matter of the independent claims.

According to the invention an imaging system for a motor vehicle is proposed, as set out in claim <NUM>, comprising a camera mounting part, at least one camera module to be mounted to said camera mounting part and a retainer ring. The camera module is provided with at least one radially outwardly directed protrusions. The retainer ring has multiple elastically deformable spring tongues. Further, the retainer ring is attachable by pushing it over the at least one protrusions under elastic deformation of the spring tongues to an attachment position. Said spring tongues clamp the camera module radially in the attachment position, wherein the tips of at least three spring tongues axially adjoin a surface of the at least one protrusion in the attachment position. The retainer ring has multiple spring elements applying an axially spring force from said camera mounting part to the tips of the at least three spring tongues in the attachment position.

Accordingly, the spring force applied by the retainer ring in the attachment position pushes the surface of the protrusion of the camera module away from the camera mounting part. This spring force pushes axially, thus preferably in alignment with the optical axis of the camera module. The axial spring force is preferably mainly generated through elastic deflection of the spring elements, wherein the spring tongues have far less deflection in this direction due to axial loads respectively due to the axial spring force. Thus, in the attachment position the spring tongues apply a radially inward directed spring force, which is perpendicular to the optical axis, in order to clamp preferably a barrel shaped part of the camera module and transfer the axial spring force from the spring elements towards the at least one protrusion of the camera module.

In order to transfer the axial spring force, the tips of at least three spring tongues are adjoin to a surface of the at least one protrusion, preferably a surface of the at least one protrusion facing the surface of the camera mounting part, and are in contact. Having three tips in contact with the at least one protrusion allows a stable positioning in the attachment position without tilting the camera module.

It is further suggested that all tips of the spring tongues axially adjoin a surface of the at least one protrusion. This allows a wider spread load transfer area of the axial spring load and an easier mounting process.

Preferably, the part of the camera module with the protrusion is put through a hole in the camera mounting part before pushing the retainer ring over the at least one protrusion. Accordingly, the part of the camera module without said protrusion is preferably not put through the hole of the camera mounting part and remains on the side of the camera mounting part opposite to the side designated for the retainer ring. Preferably, the remaining part of the camera module abuts the camera mounting part, and provides a counter bearing.

The assembly of the imaging system, which locks the camera module in place, can be inspected and verified easily, e.g. through visual inspection. Furthermore, the dimensions of the retainer ring can be verified in advance of the assembly. The retainer ring can be preferably made of one material only, which reduces complexity and costs of the imaging system. In general, a more robust design of an imaging system can be achieved.

The risk of deforming or damaging the spring elements during assembly, for example, is reduced by limiting the maximum deflection of the spring element by a limit stop when the base ring comes into contact with the camera mounting part.

It is further suggested that the spring tongues have an angle to the optical axis of the camera module smaller than <NUM>°, preferably smaller than <NUM>° in the attachment position. This reduces the deflection of the spring tongues due to axial loads, so that the axial spring loads can be provided by the spring elements in a more precise way.

Furthermore, it is preferred that the retainer ring is made of an electrically conductive material. Such a retainer ring can provide an electromagnetic shielding between the camera mounting part and camera module, achieving a second function besides ensuring pressure between the camera module and the camera mounting part. This further improves the attachment of a camera module to a camera mounting part.

It is further preferred that the retainer ring forms an electrical connection between the camera module and the camera mounting part. This ensures a tight electromagnetic shielding of the imaging system and removes the need for an electric contact elsewhere. The connection is made over the entire circumference, with the openings in the retainer ring, e.g. between spring tongues and/or spring elements, being so small that the relevant electromagnetic radiation is contained or shielded. To ensure sufficient connection between these parts the connection area is minimized thus ensuring a higher surface pressure.

According to a further preferred embodiment said electrically conductive material is a metal and/or an alloy, preferably a spring steel. This way the imaging system has a very low sensitivity to aging, to different temperatures and to temperature changes. Further on, the imaging system is enabled with a stable performance over time and over the normal usage temperatures. A low sensitivity to humidity changes can be achieved as well and the retainer ring has very low variations in dimensions over its lifetime.

According to the invention the spring tongues are arranged at an inner diameter of a basis ring of said retainer ring. This enables the use of low-cost manufacturing techniques, like stamping.

Further, according to the invention the spring elements are arranged at an outer diameter of a basis ring of said retainer ring. This also enables the use of low-cost manufacturing techniques, like stamping.

Furthermore, it is preferred that said spring tongues extent axially to a first side of the retainer ring. Axially refers to the optical axis of the camera module or an axis parallel thereto, wherein the retainer ring is preferably provided around said optical axis in the attachment position.

In a preferred embodiment said spring elements extent axially to a second side of the retainer ring. Thus, the mechanical connection between the camera module and the camera mounting part can be spring loaded axially in the attachment position.

The retainer ring is preferably provided around said optical axis in the attachment position, and axially refers to the optical axis of the camera module or an axis parallel thereto.

According to a preferred embodiment, the tips of the spring tongues have backbends directed radially outward. The backbends provide rounded surfaces of the spring tongues which are in contact with the camera module during assembly and in the attachment position. The rounded surface minimizes the risk of scratches on the camera module due to sharp edges. Further on, the tips of spring tongues are thus in a better position for locking with the surface of the at least one protrusion.

In a further preferred embodiment beads are provided in the backbends of said tips of the spring tongues. The beads increase the stiffness of the tips of the spring tongues, which can be especially beneficial under compression loads in the attachment position.

Furthermore, it is proposed that the retainer ring is a one-piece design. This allows an easy and cost-efficient production of the retainer ring with reduced complexity of the imaging system.

In a preferred embodiment the retainer ring is a closed ring. The closed ring enables higher clamping forces of the spring tongues to the camera module. A higher dimensional stability of the retainer ring can be achieved.

Furthermore, the retainer ring is preferably formed as a stamped sheet. The retainer ring can therefore be made rapidly out of sheet metal.

In the following the invention shall be illustrated on the basis of preferred embodiments with reference to the accompanying drawings, wherein:.

In <FIG> a preferred embodiment of an imaging system <NUM> for a motor vehicle is shown, wherein the figure is simplified and only a part of the imaging system <NUM> is shown.

The imaging system <NUM> comprises a camera mounting part <NUM> and a camera module <NUM> mounted to said camera mounting part <NUM>. The camera module <NUM> has an optical axis <NUM> and extents through a hole <NUM>, see <FIG>, in the camera mounting part <NUM>. The camera module <NUM> has a circular outwardly directed protrusion <NUM>. The protrusion <NUM> has a slope and/or bevel in the direction pointing away from the camera mounting part <NUM>. The protrusion <NUM> has a surface <NUM>, which is facing towards the camera mounting part <NUM>.

A retainer ring <NUM> has been pushed over the protrusion <NUM> and is shown in an attachment position. In the attachment position the camera module <NUM> has a fixed position with respect to the camera mounting part <NUM>. The retainer ring <NUM> has a basis ring <NUM>, wherein multiple spring tongues <NUM> extent radially inward and axially away from the camera mounting part <NUM> from the basis ring <NUM>. Further on, multiple spring elements <NUM> are provided radially outward of the basis ring <NUM> and extent axially towards the camera mounting part <NUM> from the basis ring <NUM>. The spring elements <NUM> have a bow which is bent away from the camera mounting part <NUM>. The spring elements <NUM> further extent along the circumference, wherein two spring elements <NUM> share the same basis and form a pair in this embodiment.

The spring tongues <NUM> clamp the camera module <NUM> below the protrusion <NUM> in the attachment position. The tips <NUM> of the spring tongues <NUM> are in contact with the lower surface <NUM> of the protrusion <NUM> which faces the camera mounting part <NUM>. Thus, an axial spring force pushes the protrusion <NUM> of the camera module <NUM> upward, which is countered by a counter bearing below the hole <NUM> of the camera mounting part <NUM>, not shown. The spring elements <NUM> are also in contact with a lower barrel shaped part of the camera mounting part <NUM> and are elastically deflected in the attachment position.

The retainer ring <NUM> is a closed ring which is clipped between the protrusion <NUM> and the camera mounting part <NUM>. The retainer ring <NUM> is made of spring steel in a one-piece design. Therefore, the retainer ring <NUM> can be made from a metal sheet in a cost-effective way. An electromagnetic shielding can be provided by the retainer ring <NUM>, increasing the electromagnetic compatibility of the imaging system <NUM>. An electric connection, e.g. ground, between the camera module <NUM> and the camera mounting part <NUM> is provided by the retainer ring <NUM> in this embodiment.

In <FIG> a cross-sectional view of the imaging system <NUM> is shown. The basis ring <NUM> and the camera mounting part <NUM> are spaced apart, wherein the spring elements <NUM> are in contact with the camera mounting part <NUM>.

The spring tongues <NUM> are bent away from the camera mounting part <NUM> and clamp the cylindrical part of the camera module <NUM> in the attachment position. In this position the spring tongues <NUM> have an angle α to the optical axis <NUM> of the camera module <NUM> smaller than <NUM>°, for example <NUM>°.

<FIG> shows a retainer ring <NUM> in a cross-sectional view. The tips <NUM> of the spring tongues <NUM> have backbends <NUM>, so that the edges of the spring tongues <NUM> are not in a radial contact with the camera module <NUM> reducing the possibility of scratching during the mounting process or assembly process. The backbends <NUM> are further provided with a bead <NUM> each which stabilizes the backbends <NUM>.

<FIG> show an imaging system <NUM> during an assembly process. In <FIG> the part of the camera module <NUM> with the protrusion <NUM> has been put through the hole <NUM> of the camera mounting part <NUM> from below. The lower part of the camera module <NUM> below the camera mounting part <NUM> is not shown. The protrusion <NUM> has a circular shape with a diameter smaller than the hole <NUM> which has also a circular shape in this embodiment.

Claim 1:
An imaging system (<NUM>) for a motor vehicle, comprising
- a camera mounting part (<NUM>), at least one camera module (<NUM>) to be mounted to said camera mounting part (<NUM>) and a retainer ring (<NUM>), wherein
- the camera module (<NUM>) is provided with at least one radially outwardly directed protrusions (<NUM>),
characterized in that
- the retainer ring (<NUM>) has multiple elastically deformable spring tongues (<NUM>), and
- the spring tongues (<NUM>) are arranged at an inner diameter of a basis ring (<NUM>) of said retainer ring (<NUM>),
- the retainer ring (<NUM>) is attachable by pushing it over the at least one protrusions (<NUM>) under elastic deformation of the spring tongues (<NUM>) to an attachment position, wherein
- said spring tongues (<NUM>) clamp the camera module (<NUM>) radially in the attachment position, wherein
- the tips (<NUM>) of at least three spring tongues (<NUM>) axially adjoin a surface (<NUM>) of the at least one protrusion (<NUM>) in the attachment position, and wherein
- the retainer ring (<NUM>) has multiple spring elements (<NUM>) applying an axially spring force from said camera mounting part (<NUM>) to the tips (<NUM>) of the at least three spring tongues (<NUM>) in the attachment position,
- the spring elements (<NUM>) are arranged at an outer diameter of the basis ring (<NUM>).