EP1825668A1

EP1825668A1 - Stray light screen for reducing the stray light impinging a camera

Info

Publication number: EP1825668A1
Application number: EP05803057A
Authority: EP
Inventors: Stefan Bischoff; Gunther Schaaf
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2004-12-06
Filing date: 2005-11-11
Publication date: 2007-08-29
Also published as: US20090122138A1; CN101073252A; JP2008522891A; DE102004058683A1; WO2006061304A1

Abstract

The invention relates to a camera module (10) comprising a stray light screen (12) that is mounted upstream from a lens (52) of the camera module (10). Said stray light screen (12) rests against the interior face (16) of a pane (14). The inner side (28) of the stray light screen (12) is provided with a structure (34) that reduces incident stray light (32, 36). Said structure (34) that reduces incident stray light (32, 36) encompasses at least one secondary, ramp-shaped structure (56, 80, 86) which extends perpendicular to the optical axis (20) of the camera array (10).

Description

Lens hood for reducing stray light falling into a camera

Technical area

In motor vehicles come to display and processing the current driving situation

Night View systems are used which have an infrared camera mounted directly behind the windshield at the level of the rearview mirror. Such used infrared cameras have to reduce the influence of disturbing stray light on a lens hood. The inserted lens hood reduces the influence of stray light entering the camera.

State of the art

From DE 102 37 607 Al a camera arrangement for motor vehicles is known. The camera assembly includes a camera located in the vehicle interior behind the

Windscreen is arranged. The camera is from one on the inside of the

Windshield attached bracket added. The holder forms according to this solution, a cap, which encloses the space between the windshield 10 and a camera lens light and dustproof, wherein the camera is arranged on the windshield applied to the end of the cap. The

Cover has a bordered by a peripheral edge light entrance window and lies with the peripheral edge of the windshield so that the

Cover is closed in the region of the light entrance window of the windshield. From DE 102 52 446 Al a camera device is known. In particular, this camera device is one that is suitable for a portable electrical device. The camera apparatus includes an electronic camera element for receiving light emitted from a light source. An optical element is also provided for breaking the light emitted by the light source, wherein the optical element is arranged between the electronic camera element and the light source. Furthermore, an absorption element is provided which is arranged between the electronic camera element and the light source in order to control the intensity of the light impinging on the camera element. The absorption element is according to DE 102 52

446 known solution made of a photochromic material.

Previously used in motor vehicles stray light apertures have for masking reflected lateral light on the inside of a staircase-like structure. Reflected side light is reflected back to the outside by the structure formed on the inside of the lens hood. An optimization of the parameters with regard to the height of the steps of the staircase-like structure, the step step widths and the angle between vertical and horizontal surface largely reduces the scattered light. Furthermore, the inside of the lens hood is kept in a strongly absorbing black color.

However, there are also such unfavorable situations in which stray light incident from above, e.g. Sunlight or the light of street lamps, invade the camera. Here, a further reflection takes place on the windshield, which leads the light completely or partially to the camera. The width and the

Heights of the stair structure formed in the scattered light diaphragm on the inside have no influence on this effect. Optimizing the angles of the staircase steps to reduce stray light from above, however, would reduce the primary effect, i. To achieve the reduction of the incident light from the front, undesirably greatly attenuate.

Remedy could be provided by the creation of "light traps"

Light traps could be represented by small pits, in which the light is reflected back and forth until it has lost its intensity through absorption at the surfaces. For this purpose, however, a complex production is required, with would involve a disproportionate effort, which relates to the production of such small structures in the form of holes on the individual stages of provided on the inside of the lens hood stair structure. Furthermore, it is currently hardly possible to prevent with reasonable effort that the edges are strongly rounded when applying paint. It has been found that when applying

Color on the primary structure within the lens hood due to the running of the paint during drying, the edges are strongly rounded, and the resulting fillet radii have the same geometric order as light traps. This would change the original, light traps containing structure so much that the desired function could no longer be met.

Presentation of the invention

According to the invention, it is proposed to modify the step-like structure formed on the inside of the scattered-light diaphragm in such a way that a further secondary stair-like structure is applied to the already existing staircase-like structure with a step sequence in the direction of the optical axis (X-axis). On the secondary staircase-like structure, the sequence of steps of the further staircase-like structure is orthogonal to the optical axis (i.e., parallel to the Y-axis). Alternatively, the secondary stair-like structure could also be formed of small sloping ramps, which are placed one behind the other on the already existing steps of the primary, already existing staircase-like structure.

Thus, incident light from above such as e.g. Sunlight or the light of one

Street lamp with a direction of incidence, which is almost equal to the Z direction and whose Y component is equal to 0, which was previously reflected back with Y = O, now a non-zero Y component is impressed. Thus, a large part of such, from above incident light scattered past the lens.

The advantages of the proposed solution according to the invention are to be seen in the fact that only a slight modification of an already proven and used arrangement is required. The advantage of the good reduction of scattered light with the first staircase-like structure formed in the scattered light diaphragm on the inside with respect to frontally incident stray light (X-direction) becomes - A -

maintained in full. By adding a basically similar structure, i. a secondary staircase-like structure - as far as the geometry and the dimensions are concerned - it can be ensured that the manufacturing method with which the staircase-like structures are produced on the inside of the lens hood can in principle remain the same.

Furthermore, the provision of "light traps" avoided by the proposed solution according to the invention, which can be formed only with a disproportionate effort on the inside of a lens hood.

drawing

With reference to the drawing, the invention will be described below in more detail.

It shows:

FIG. 1 shows a schematic representation of the starting situation with a scattered-light diaphragm arranged in front of a camera,

Figure 2 is a cross-section through a known from the prior art

Lens hood,

FIG. 3 shows light incident from above on the scattered-light diaphragm according to FIG.

FIG. 4 shows the reflection conditions of incident light at the top and FIG

Stray light stop according to FIG. 2,

FIG. 5 shows a secondary staircase-like structure superimposed on the staircase-type structure according to the invention,

6 shows the beam path from above incident light on a primary staircase-like structure on the inside of the lens hood, FIG. 7 shows the beam path from above incident light on the inside of a scattered light diaphragm, which, in addition to the primary staircase-like structure, has the further secondary staircase-like structure proposed according to the invention,

Figure 8 shows the representation of a primary structure with different from 0 ° and 90 °

angles,

9 shows the illustration of a step-shaped staircase-shaped primary structure, which comprises more than two elements and has a bevelled edge,

10 shows the representation of a stepped primary structure in which the steps of the stairs are provided with angles other than 0 ° and 90 ° and with a bevelled edge, and

Figure 11 shows the representation of a ramp-shaped secondary structure, which is superimposed on the staircase-shaped primary structure and is designed axially symmetrical to the optical axis.

variants

Figure 1 shows a schematic representation of the currently prevailing beam paths on a camera received on the inside of a windshield.

The illustration according to FIG. 1 reveals that a scattered-light diaphragm 12 is connected upstream of a camera module 10. The scattered light diaphragm 12 abuts against an inner side 16 of an inclined windshield 14. The outside of the windshield 14 is identified by reference numeral 18. In the coordinate system according to the

Representation in Figure 1, the X-axis is identified by reference numeral 20. The X-axis 20 represents the optical axis of the camera 10. Reference numeral 22 identifies the Z-axis, ie in the present case the vertical axis. The scattered light diaphragm 12 comprises an outer side 30 and an inner side 28. Light incident directly on the outer side 30 of the scattered light diaphragm 12 is masked out, represented by the arrow 26. By the windshield 14 from the outside 18 to the inside 16 by passing indirect light 32, the scattered light aperture 12 is reflected on the inside 28 and falls into an objective 52 of the camera module 10 a.

The illustration according to FIG. 2 shows a primary stepped structure formed on the inside of the scattered light diaphragm.

In the illustration according to FIG. 2, the inside of the scattered light diaphragm 12 is reproduced on an enlarged scale. The known from the prior art diffuser panel 12 comprises a primary staircase-like structure 34, which on the inside

28 of the lens hood 12 is formed. The outer side 30 of the scattered light diaphragm 12 extends in accordance with the inclination of the scattered light diaphragm 12 in order to bridge the distance between the objective 52 of the camera module 10 and the inner side 16 of the windscreen 14, not shown in FIG.

The primary staircase-like structure 34 comprises individual stages 48. A light beam 32, 36 incident into the lens hood 12 is reflected from the top of a corresponding step 48 to the front of the further step of the primary staircase-like structure 34 adjoining the step 48 and from this again emitted as reflected light 38. The light beam 38 thus represents reflected indirect light 32, 36 which does not enter the objective 52 of the camera module 10.

The illustration according to FIG. 3 shows the beam path of light incident from above, which is incident on the scattered light diaphragm 12 and reflected into the camera module 10.

With top-incident light 40 as shown in Figure 3, e.g. Sun rays or the light of street lamps or other sources of light meant. From above incident light 40 hits the inside 28 of the lens hood

12. As shown in FIG. 2, the inner side 28 of the scattered light diaphragm 12 is provided with a primary staircase-like structure 34, which, however, is not shown in FIG. 3 for purposes of illustration. At the primary staircase-like structure 34 having inner side 28 of the lens hood 12 is reflected from above incident light 40 corresponding to the arrow 42 to the inside 16 of the windshield 14. From the inner side 16 of the windshield 14, the reflected light 42 is guided according to the beam path 44, 46, in the lens 52, which is connected upstream of the camera module 10.

In the illustration according to FIG. 4, the beam path from the top into the

Lens aperture 12 incident light 40 reproduced on an enlarged scale. From the illustration according to FIG. 4, it can be seen that light 40 incident from above is guided by the steps 48 of the primary staircase-like structure 34 according to the arrow 42 to the inside of the windshield, which is not shown in the illustration according to FIG. At a correspondingly unfavorable angle of incidence of the incident light from above 40, the primary staircase-like structure 34 is ineffective; According to the beam path shown in FIG. 3, incident light 40, after reflection on the inner side 16 of the windshield 14, is guided directly into the objective 52 upstream of the camera module 10 and thus falls directly into it, thus considerably disturbing the image recording quality of the camera module 10

For the sake of completeness, it should be noted that each step 48 has a sharp edge 50. The straylight 12 is a U-shaped structure whose open side is covered by the windshield 14. At the two opposite legs of the U-shaped stray light aperture, the primary ramp-shaped structures are formed; further in the bottom of the U-shaped profiled structure.

The illustration according to FIG. 5 shows a scattered-light diaphragm designed according to the invention.

In the illustration according to FIG. 5, the scattered light diaphragm 12 is only partially reproduced. The scattered light diaphragm 12 comprises on the inner side 28 the primary staircase-like structure 34. This has individual steps 48, which each have a flat surface 58 and an end face 70. Further, the steps 48 include an edge 50 where the flat surface 58 and the end face 70 meet. The primary staircase-like structure 34 is located on the inner side 28 of the lens hood 12, while the outer side 30 is substantially straight, see. Representations according to Figures 2 and 4.

On the flat surface 58 of a step 48, a secondary ramp-shaped structure 56 is applied in the illustration according to FIG. The secondary ramped Structure 56 includes individual ramped elevations. The individual ramped bumps include a deflecting surface 82 inclined with respect to the flat surface 58 of the primary staircase structure 34 which is inclined by a pitch angle 84 with respect to the flat surface 58 of the step 48. The deflection surface 82 is bounded by an end face 66. In the illustration according to FIG. 5, the secondary ramp-shaped structure 56 superimposed on the primary staircase-like structure 34 is arranged so that the deflecting surfaces 82 are designed to be inclined towards the outside of the scattered-light diaphragm 12. Corresponding to the width of the scattered light diaphragm 12, the secondary ramped structure 56 comprises a plurality of ramp-shaped elevations.

For spatial orientation, reference is made to the coordinate system denoted by reference numeral 68, in which the orientations of the X-axis 20 corresponding to the optical axis, the Z-axis 22 and the Y-axis 54 are shown. The secondary ramped structure 56 thus extends substantially corresponding to the Y-axis 54. With respect to the Z-axis 22, the deflection surfaces 82 of the secondary ramped structure 56 are inclined by the pitch angle 84. Following the solution proposed by the invention, the sequence of individual ridges formed is orthogonal to the X-axis 20, i. parallel to the Y-axis 54.

Top-incident light 40 and 62, respectively, impinge on the deflection surfaces 82 of the secondary ramp-shaped structure 56 and are reflected according to the lead angle 84 as indicated by the arrow 64. As a result of the solution proposed according to the invention, the reflected light 64 is impressed on a component extending in the direction of the Y-axis 54. The light 64 reflected by the secondary ramped structure 56 is reflected and absorbed at a side surface of the scattered light orifice 12 and reflected to the opposite side surface of the scattered light orifice and so on.

Instead of the plurality of ramp-shaped elevations shown in FIG. 5, it would also be possible to form on the level 58 of the individual steps 48 a steadily rising staircase structure which has individual small steps. It is also possible to form the deflecting surfaces 82 in a pitch angle 84 other than that shown in FIG. 5 relative to the flat surface 58. By the proposed solution according to the invention at the scattered light aperture 12th provided primary staircase-like structure 34, which is formed substantially as a 2D structure in the X, Z direction and then moved parallel in the Y direction, to a three-dimensional structure by on each of the steps 48 of the primary staircase-like structure 34 another staircase or ramp-shaped secondary structure 56 is placed. The individual ramp-shaped elevations, formed by the

Deflection surface 82 of end face 66 and lead angle 84 provide new structural parameters, e.g. Inclination and height of the individual ramp-shaped elevations and the number of ramps, through the optimization of which a strong reduction of incident light scattering light 40, 62 can be achieved. The ramped elevations of the secondary ramped structure 56 include perpendicular end faces 66 and deflection surfaces 82 oriented in pitch angle 84. Thereby, new structural parameters e.g. in terms of the pitch angle 84 of the deflection surface 82 as well as the height of the end face 66 and the number of ramp-shaped elevations per stage 48 given.

In a further advantageous embodiment, the secondary ramp-shaped structure 56 could be formed axially symmetrically with respect to the optical axis 20, which coincides with the X-axis, to the center of each step 48 of the primary staircase-like structure 34. This means that not all ramped elevations of a secondary ramp-shaped structure 56 on the flat surface 48 to one side of the

Lens aperture 12 show, but each to the nearer edge of the lens hood 12th

The illustration according to FIG. 6 shows the beam path from above incident light in a camera lens.

From the illustration according to FIG. 6, it can be seen that light 40, 62 incident on the flat surface 58 of the step 48 is reflected from above approximately vertically or vertically. The steps 48 are divided by edges 50 in the flat surface 58 and the end face 70. On the flat surface 58 incident light 40, 42 is reflected according to the reflected light 42 at an impact location 72 on the inside of a windshield 14, not shown in Figure 6 and falls as reflected light 44, 62 directly into the lens 52, which the camera module 10th upstream. The primary staircase-like structure 34 is incorporated in the inside 28 of the lens hood 12. FIG. 7 shows the secondary ramp-shaped structure applied according to the invention to the inside of the scattered-light diaphragm on the primary staircase-like structure 34 formed there.

Although the proposed secondary ramped structure 36 is merely applied to a flat surface 58 of step 48 in the illustration of FIG. 5, it is quite possible to apply the secondary ramped structure 56 to each planar surface 58 of each step 48 of the primary staircase structure 34 , The illustration according to FIG. 7 shows a further, secondary ramp-shaped structure 80 as well as a third secondary ramp-shaped structure 86 which are respectively applied to the flat surfaces 58 of the individual steps 48 of the primary staircase-like structure 34. The end faces of the individual ramped elevations are indicated by reference numeral 66, while the deflecting surfaces are indicated by the reference numeral 82.

To clarify the achievable with the proposed solution according to the invention beam path reference is made to the coordinate system 68. The Z-axis is designated by reference numeral 22, the X-axis by reference numeral 20 and the Y-axis by reference numeral 54. The X-axis 20 coincides with the optical axis of the

Camera lens 52 and the camera module 10 together.

Due to the inclination of the individual deflecting surfaces 82 of the ramped elevations of the ramp-like secondary structure 56, a beam 40, 62 perpendicularly incident from above is inclinedly reflected at the deflecting surface 82. The reflected light 64 arrives at a modified impact location 74 on the inside 16 of the windshield 14 and is reflected therefrom past the camera lens 52 as a deflected beam according to reference numeral 78. Accordingly, light 40, 62 incident from above can not adversely affect the image-recording quality of the camera lens 52 or of the camera module 10 subordinate thereto, since the rays incident from above

40, 62 as rays 78 are guided past the camera lens 52.

By the solution proposed according to the invention, an optimization of a previously used scattered-light diaphragm 12 can be achieved while maintaining the manufacturing method selected for forming the primary staircase-shaped structure 34. It is only a slight modification of an already proven arrangement possible, which ensures the advantage of good reduction of stray light coming from X-direction 22 coming. By modifying the primary staircase-like structure 34 on the inner side 28 of the scattered light diaphragm 12, the good properties of the previously known solution can be maintained. By adding a similar structure in terms of shape and

Dimension, the previously used proven manufacturing process can be maintained in principle.

The illustration according to FIG. 8 shows a primary structure which has a stepped shape. The primary structure 34 comprises each vertically formed

End faces 70 and flat surfaces 58 which abut one another along an edge 50.

By the end faces 70 and the flat surfaces 58 each stages 48 are formed. In the embodiment of the primary structure shown in FIG. 8, the flat surfaces 58 extend at an inclination angle α different from 0, i.e., 0. the flat surfaces 58 are formed inclined either upwardly or downwardly with respect to the edges 50 of the individual steps 58. With respect to the end faces 70 of the individual stages

48, these are oriented at an inclination angle β, which is not equal to 90 °. This means that the end faces 70 of the individual stages 48 in relation to the vertical in one

Angle range between 80 ° and 110 ° are designed to extend.

The illustration according to FIG. 9 shows a further configuration possibility of the primary structure.

According to the embodiment variant of the primary structure 34 shown in FIG. 9, this comprises both planar surfaces 58 and end sides 70, which, however, do not abut against one another along a common edge 50, but rather via an obliquely running one

Surface 88 are interconnected. The inclined surface 88 shown in the illustration according to FIG. 9 replaces the edge 50 in accordance with the edge 50 of the respective step 48 shown in FIGS. 4, 6 and 8. In the embodiment according to FIG. 9, the angle by which the bevelled surface 88 lies in relation to the flat surface

58 of the step 48 is oriented, for example in the order of between 20 ° and 30 °.

The illustration according to FIG. 10 shows a further possible embodiment for a primary staircase-shaped structure. The primary structure 34 as shown in FIG. 10 represents a combination of the features of the embodiment variants according to FIGS. 8 and 9. In the embodiment variant according to FIG. 10, the flat surface 58 is connected to the end face 70 of a step 48 via an inclined surface 88 , The angle of inclination about which the inclined surface 88 is oriented relative to the flat surface 58 is advantageously on the order of between 20 ° and 30 °.

From the illustration according to FIG. 10, it is also apparent that the flat surface 58 is inclined at an angle α with respect to the X-axis 20. In the illustration according to FIG. 10, the flat surface 58 extends at an angle of a few

Degree inclined upwards.

Furthermore, the illustration according to FIG. 10 can be taken away from the fact that the end face 70 is inclined at an angle β, not equal to 90 °, relative to the vertical.

The illustration according to FIG. 11 shows a further embodiment of the primary structure 34, which is superimposed on two secondary ramp-shaped structures 56 oriented in opposite directions. Two oppositely extending secondary ramp-shaped structures 56 each have a plurality of ramp-shaped elevations, each comprising the deflection surface 82.

The deflecting surfaces 82 are oriented such that reflected light 64 deflected therefrom meets the two spaced-apart, vertically extending legs of the U-shaped stray light stop 12. Each of the baffles 82 of the secondary ramp-shaped structure 56 is inclined by the angle of inclination 85 and includes an end face 66. In the illustration according to FIG

11, the secondary ramped structures 56, which are oriented counter to one another, are located on a flat surface 58 of a step 48 of the primary structure 34. It is, of course, possible for the secondary ramped structures 56 adjoining each other on a central axis 90 in the illustration according to FIG to arrange an angle α inclined flat surfaces 58 to influence the reflection of incident light in the lens hood 12 light. In the illustration according to FIG. 11, the end faces 70 of the steps 48 are arranged vertically, but they could, as explained above in connection with FIGS. 9 and 10, be oriented by the angle of inclination β deviating from the vertical in order to improve the reflection properties.

Claims

claims

1. Camera arrangement (10, 52) for motor vehicles with a camera module (10) and a lens hood (12), wherein the lens hood (12) on its inside (28) has a stray light incidence (32, 36) reducing structure (34), characterized in that the structure (34) reducing the scattered light incidence (32, 36) comprises at least one secondary, ramp-shaped structure (56) oriented orthogonally to the optical axis (20) of the camera arrangement (10, 52).

2. Camera arrangement (10, 52) for motor vehicles according to claim 1, characterized in that the scattered light incidence (32, 36) reducing structure (34) is formed step-shaped.

3. Camera arrangement (10, 52) according to claim 1, characterized in that the secondary, ramp-shaped structure (56) comprises a plurality of ramp-shaped elevations, each having a deflection surface (82).

A camera assembly (10, 52) according to claim 3, characterized in that the baffles (82) are disposed at a pitch angle (84) with respect to steps (84) of a primary stray light incidence (32, 36) reducing structure (34) ,

5. Camera arrangement (10, 52) according to claim 1, characterized in that the secondary, ramp-shaped structure (56) deflects incident light (40, 62) onto points of incidence (74), from which light incident from above (40, 62) is deflected past the camera arrangement (10, 52).

6. Camera arrangement (10, 52) according to claim 1, characterized in that the secondary, ramp-shaped structure (56) is formed axially symmetrically with respect to the optical axis (20) of the camera arrangement (10, 52).

7. Camera arrangement (10, 52) according to claim 6, characterized in that the deflection surfaces (82) are oriented with respect to the optical axis (20) facing the outer region of the lens hood (12).

8. Camera arrangement (10, 52) according to claim 6, characterized in that the deflection surfaces (82) with respect to the optical axis (20) each have end faces (66) whose extension in the direction of the Z-axis (22) out with increasing distance from the optical axis (20) increases.

9. camera arrangement (10, 52) according to claim 1, characterized in that in the direction of the optical axis (20) seen in the direction of the lens (52) of the

Camera module (10) a plurality of secondary ramped structures (56, 80, 86) on steps (48) of the primary, stepped structure (34) are arranged.

10. Camera arrangement (10, 52) according to claim 1, characterized in that the primary, stepped structure (34) and the secondary, ramp-shaped structure

(56) are colored black.

11. Camera arrangement (10, 52) according to claim 3, characterized in that the ramp-shaped elevations of the secondary, ramp-shaped structure (56) in the direction of the Y-axis (54) adjacent to each other.

12. Camera arrangement (10, 52) according to claim 11, characterized in that the end faces (66) of the ramp-shaped elevations adjoin foot points of inclined deflection surfaces (82).

13. Camera arrangement (10, 52) according to claim 2, characterized in that the scattered light incidence (32, 36) reducing structure (34) stages 48), the adjacent flat surfaces (58) and end faces (70), wherein the flat surfaces (58) by an inclination angle α relative to the horizontal and the End sides (70) are designed inclined at an inclination angle ß relative to the vertical.

14. Camera arrangement (10, 52) according to claim 2, characterized in that the primary structure (34) has steps (48) whose flat surfaces (58) and their

End faces (70) are connected by means of a tapered surface (88).

15. Camera arrangement (10, 52) according to claim 2, characterized in that the primary structure (34) has steps (48) each with a flat surface (58) and an end face (70), wherein the flat surfaces (58) to an inclination angle α in

Are arranged inclined with respect to the horizontal and the end faces (70) inclined at an inclination angle ß with respect to the vertical and the flat surfaces (58) and the end faces (70) of each stage (48) of the primary structure (34) are connected to each other via a tapered surface (88).

16. Camera arrangement (10, 52) according to claim 2, characterized in that the primary structure (34) comprises a plurality of steps (48) on the flat surface (48) at least two secondary ramp-shaped structures (56) are arranged, the deflection surfaces ( 82) are oriented in opposite directions to each other.

17. Camera arrangement (10, 52) according to one of the preceding claims, characterized in that the scattered light diaphragm (12) on the inside (16) of a disc (14).