EP2710806A1

EP2710806A1 - Checking apparatus for a camera, and a method for checking a camera

Info

Publication number: EP2710806A1
Application number: EP12709330.0A
Authority: EP
Inventors: Ulrich Seger; Uwe Apel; Carina RAIZNER
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2011-05-19
Filing date: 2012-03-20
Publication date: 2014-03-26
Also published as: CN103548349A; DE102011076133A1; WO2012156131A1; US20140152845A1

Abstract

The invention relates to a checking apparatus for a camera, particularly from driver assistance systems in a motor vehicle, comprising a mount for a camera for at least two light sources for emitting test light to the camera, wherein the mount and at least one of the at least two light sources are arranged so that their relative situation and position are fixed in relation to one another, and a control device which is designed to operate the at least two light sources such that, in each case in chronological order, one light source is on and the at least one further light source is off. The invention likewise relates to a checking method for a camera and to a checking system.

Description

Description title

Test device for a camera and a method for testing a camera

The invention relates to a test device for a camera and a method for testing a camera. The invention also relates to the use of a

Test device and a test system.

State of the art

Cameras are used in various ways in the prior art, including in the automotive industry. You can, for example, related to

Driver assistance systems serve to observe the traffic space in front of a motor vehicle. These cameras have a high dynamic range and a large brightness range in order to enable shooting in the desired quality both during the day and at night. Due to the large brightness range, these cameras are sensitive to errors in the optics, which cause stray light or stray light. Optical aberrations can be caused by frame reflexes, lens compensation errors, particles or scratches. In the field of view of the camera then the spurious or scattered light in the form of artifacts can be seen. Artifacts can on

occur in different areas in the image field of the camera and are perceived by viewers of the image as disturbing or quality-reducing. In addition, it is possible that the interference light causes an overshoot of certain details and / or darker objects, which are then no longer recognizable in the image of the camera.

To check such a highly dynamic camera for errors in the optics, usually the highly dynamic camera is irradiated in a dark environment with light from a light source and evaluated the corresponding recorded image of the camera from the light source. The highly dynamic camera is rotated or tilted, so that the entire image area of the highly dynamic camera irradiated with light from the light source and correspondingly recorded image of the highly dynamic camera can be evaluated. To evaluate the image of the highly dynamic camera, a visual inspection is performed by a viewer who, for example, on a Screen displayed on the highly dynamic camera recorded image for artifacts examined. This study is based on an error catalog that shows typical errors. The viewer then evaluates corresponding artifacts based on the error catalog. Error criteria are, for example, brightness, width and / or length of the corona-like rays emanating from a location of the light source.

In claim 1, a test device for a camera is defined, in particular of driver assistance systems in a motor vehicle, comprising a holder for a camera, at least two light sources for emitting test light to the camera, wherein the holder and at least one of the at least two light sources their relative position and position are fixed to each other, and a control device which is designed to actuate the at least two light sources such that in each case a light source is switched on in chronological order and the at least one further light source is turned off and wherein the control device is formed, to actuate the at least two light sources in synchronism with a picture feed of an image of the camera.

Claim 7 defines a test method for a camera, in particular for cameras in driver assistance systems in a motor vehicle, preferably suitable for execution on a test apparatus according to at least one of claims 1-6, comprising the steps of arranging the camera in a holder, emitting test light the camera by means of at least two light sources, recording the test light by the camera, and evaluating the recorded test light, wherein the holder and at least one of the at least two light sources are fixed relative to each other with respect to their relative position and position and wherein the at least two light sources are actuated in such a way so that in each case one light source is switched on in chronological order and the at least one further light source is switched off and the at least two light sources are actuated in synchronism with a picture feed of an image of the camera.

In claim 8, a test system for an at least partially transparent object is defined, comprising a test device according to at least one of claims 1-6, a camera and an object holder for an object to be tested, at least partially transparent object, wherein the object holder in the light path between the at least two light sources and the camera is arranged, and an evaluation device which is connected to the camera for, in particular automatic, evaluation of recorded by the camera test light.

Advantages of the invention

The test apparatus, the test method and the test system have the advantage that a review of a highly dynamic camera and / or an at least partially transparent object can be performed easily and quickly. In addition, the test system and the test device can be made more compact.

Advantageous developments of the invention are described in the subclaims. According to an advantageous development of the invention, at least one of the at least two light sources comprises a collimator device and / or is designed as a light-emitting diode. The advantage achieved is that it allows an even more compact device to be provided. In addition, the LEDs are compared to conventional light sources faster switchable and produce a more stable in intensity and wavelength light.

According to a further advantageous development of the invention, an evaluation device which can be connected to a camera to be tested is arranged for the automatic evaluation of the test light received by the camera. The advantage achieved is that it can be evaluated quickly and inexpensively in a simple and reliable way errors of the camera or artifacts.

According to a further advantageous embodiment of the invention, an optical path between each one light source and the camera is substantially the same. In this way, it is ensured that each of the light sources irradiates the camera with the same intensity, thus enabling maximum reliability and accuracy in the evaluation of images of the camera by means of the light sources and thus the detection of artifacts. According to a further advantageous embodiment of the invention, the light path is less than 75 cm, in particular less than 50 cm, preferably less than 40 cm. In this way, an extremely compact testing device is provided. According to a further advantageous embodiment of the invention, the at least two light sources in a regular manner, in particular grid-shaped, arranged. In this way, the light sources in the image taken by the camera generate a regular grid of spots of the respective light sources, thus simplifying the examination of the camera for artifacts.

According to a further advantageous development of the test system, the at least two light sources and the camera to be tested are arranged such that the light sources are arranged in a regular grid on a recording of test light of the light sources through the camera. In this way, the light sources in the image taken by the camera generate a regular grid of spots of the respective light sources, thus simplifying the examination of the camera for artifacts.

According to a further advantageous embodiment of the test system, the object holder is arranged to be movable and in particular controllable by means of the control device. The advantage achieved here is that simply and quickly the entire image taken by the camera of the test light transmitted through the at least partially transparent object can be examined for possible artifacts, in particular automatically, so that it is possible to obtain conclusions about a surface condition of the at least partially transparent object.

According to a further advantageous embodiment of the invention, the camera has a dynamic range of at least 10 ⁴ , in particular at least 10 ⁵ , preferably 10 ⁷ . The advantage achieved here is that even more simple surface defects of optics, their degree of occupancy, etc. can be checked by means of the test system.

Brief description of the drawings

Further features and advantages of the invention will become apparent from the description of embodiments below with reference to the drawings. It shows 1 shows a cross section of a testing device according to a first embodiment of the present invention in a schematic form.

FIG. 2 shows an image of a light source taken by a camera to be tested with a test device according to FIG. 1; FIG. and

3 shows a light source with a collimator device of a test device according to FIG. 1.

Embodiments of the invention

Fig. 1 shows a cross section of a test apparatus according to a first embodiment of the present invention in a schematic form.

In Fig. 1, reference numeral 1 denotes a test apparatus for a camera 4 comprising an optic 4a. The camera 4 is connected to an evaluation device 7, 8, wherein reference numeral 7 designates an evaluation device which automatically evaluates a recorded image of the camera 4. Reference numeral 8 denotes a monitor on which the image of the camera 4 and optionally the evaluated

Results of the evaluation device 7 are displayed for a user. The camera 4 is arranged in a holder 5, which in particular firmly against the

Light sources 2a-2e is arranged. The light sources 2a-2e are at least partially arranged in a circle around the imaging optics 4a of the camera 4 so that they can act on the camera 4 with respective light L ₂ , L ₃ . The light sources 2a-2e each comprise a collimator device 3, which essentially parallelizes light from a respective light-emitting diode 3 'for acting on the imaging optics 4a of the camera 4 with the light. The light sources 2a-2e are each connected to a control device 6. In Fig. 1, a connection of the light sources 2b and 2c to the control device 6 is shown. Of course, the other light sources 2a, 2d and 2e are each connected to the control device 6.

In order to be able to record as reliably as possible only the light of the light sources 2a to 2e by means of the camera 4, the test apparatus is in particular designed such that Background radiation, so for example, reflections through the imaging optics 4a, which can meet again of the walls of the test apparatus 1 on the imaging optics 4a, are reduced as much as possible. For this purpose, these are for example arranged at the light sources slats 1 1, which prevent such backscatter. This improves the recognizability of artifacts on the camera 4

taken picture. The test apparatus 1 is designed so that of darker areas in the test apparatus 1, a radiation power of less than 0, 1%, in particular less than 0.05%, preferably less than 0.02% of the beam density of a light source 2a-2e is reflected ,

The control device 6 is likewise designed so that it can control the light sources 2a-2e in such a way that a respective light field of the light sources 2a-2e, their brightness and / or saturation can be changed or adjusted. Moreover, the light sources 2a-2e are formed as stabilizable light sources 2a-2e, that is, they have a substantially constant emission power in a given one

Wavelength band. The control device 6 is also connected to the evaluation device 7 and designed so that the control device 6 synchronizes an image intake of the camera 4 when taking a picture and the switching on and off of the light sources 2a-2e.

In order to examine the camera 4 arranged in the holder 5 for optical artifacts, etc., the light sources 2a-2e are now switched on one after the other for a predefined period of time, one after the other, and on the basis of the camera 4

recorded image, for example, with the help of the monitor 8, each analyzed whether and / or to what extent artifacts on the captured images by the camera 4 are present. The analysis is advantageously carried out by means of computer-aided

Image processing performed, in particular, the evaluation of an image of the camera 4 from a light source 2a-2e in real time and thus allows an extremely fast and objective evaluation of scattered light artifacts in the optics. For this purpose, artifacts can be characterized by their characteristic properties, such as length, thickness and angle of a jet-shaped artifact, by means of automated processing,

For example, by means of light / dark comparison of surrounding grid-shaped arranged pixels, are determined and then classified by an error catalog. For example, if you assign a key figure to each artifact, you can use the Metric and / or a sum of metrics various artifacts

be decided whether the camera meets a desired accuracy.

These results of the analysis of possibly occurring scattered light artifacts in the optics of the camera 4 are buffered in the evaluation device 7 and later serve as reference patterns when at least partially transparent objects 10 in the beam path between the light sources 2a-2e and the camera 4 are examined. After analyzing and evaluating scattered light artifacts of the camera 4, the test apparatus 1 is calibrated and can now be used to measure surface defects of at least partially transparent objects 10. In this way, their occupancy rate, for example, by condensation, contamination, icing, etc. are analyzed or lens qualities of lenses are characterized.

Scratch marks on, for example, an objective are then displayed in the image of the light sources 2a-2e as radially symmetric rays away from the center of the image of the recorded light source 2a-2e when the at least partially transparent object 10 is placed in a holder 12. In this case, any scattered light artifacts of the imaging optics 4a of the camera 4, in the previous

Calibration of the test apparatus 1 were cached, taken into account in the evaluation of the at least partially transparent object 10 and excluded in the analysis in particular.

It is also possible to measure with the test apparatus 1 a manufacturing quality, such as polishing grades, etc. of optical surfaces, as these the

Change scattering light properties in the optical path between light sources 2a-2e and camera 4. Finally, lens reflexes can be measured, which can lead to a reduction of lens performance in cameras in highly dynamic applications. Such applications are for example vehicle cameras in

Driver assistance systems and security cameras, their performance

For example, by incident in the field of sunlight, can be greatly affected or reduced. It is also possible, if the lens is provided with an anti-reflection coating, based on a means of the test device. 1

the quality of the coating to be determined and / or checked. In Fig. 1, a windshield 10 of a vehicle is shown as an at least partially transparent object. This is in the test apparatus 1 in the optical path between light sources 2a-2e and the camera 4 to detect defects, soiling or wear of the windshield 10. Then, as described above, the light sources 2a-2e are turned on alternately, and the transmission of the light of the light sources 2a-2e through the

Windshield 10 recorded and evaluated by the camera 4. If the image captured by the camera 4 has stray light artifacts, then

if necessary detected a defect. The control device 6 is with the

Evaluation device 7 is connected and designed so that the control device 6 synchronizes the image intake of the camera 4 and the switching on and off of the light sources 2a-2e.

FIG. 2 shows an image of a light source taken by a camera to be tested with a test apparatus according to FIG. 1. FIG. 2 shows an image of the light source 2b shown on a monitor 8 by means of the camera 4. In the image, a grid dimension 100 can be seen, which is substantially square and is placed over the image. Each crossing point of the grid corresponds substantially to a light source 2a-2e. In Fig. 2, the recorded light L _{2 of} the light source 2b is shown in the upper right area. In the center of the received light is seen a substantially symmetrical bright spot 20 having a substantially circular corona 20a. Furthermore, in the radial direction and according to FIG. 2 to the bottom left two opposite to the dark

Background lifting beams 20b shown. These deviate from the ideal, that is radially symmetrical, light distribution of the light source 2b and thus show a scattered light artifact. Depending on the length, thickness and / or the rays 20b, this is called

Aberration or scattered artifact classified.

FIG. 3 shows a collimator device of a light source of a test device according to FIG. 1.

FIG. 3 shows a light source 2a with a collimator device 3. The light source 2a comprises in a housing a light emitting diode 3 ', which light 30 in

Essentially radiates in the radial direction. The light rays of the light 30 are thus not parallel. These now encounter a collimator device 3, comprising a diaphragm 20, the outer light beams, ie those which are farther away from the center of the diaphragm as given, hides. The remaining light rays 30 pass through the Aperture 20 through and reach an objective 21, in particular an achromatic NIR lens. After passage of the light rays through the objective 21, they are essentially parallel (provided with reference number 31 in FIG. 3).

Overall, the invention has several advantages. The invention enables the reliable measurement of lens reflections, which in particular lead to the reduction of lens performance in highly dynamic applications. Likewise, the present invention makes it possible to check and evaluate cameras, objectives, coverslips, cover disks or at least partially optically transparent and / or reflective interfaces for optical defects based on scattered and / or stray light. In addition, it is possible to check coatings, polishing qualities of surfaces or coatings, for example in anti-reflective coatings. Another advantage is that the

Check in a simple and reliable way can be done objectively and quickly by means of the test device or the test system.

Although the present invention has been described above with reference to preferred embodiments, it is not limited thereto, but modifiable in many ways.

Claims

Claims 1. Test device (1) for a camera (4), in particular of

Driver assistance systems in a motor vehicle, comprising,

a holder (5) for a camera (4),

at least two light sources (2a, 2b, 2c, 2d, 2e) for emitting test light (L ₂ , L ₃ ) to the camera (4),

wherein the holder (5) and at least one of the at least two light sources (2a,

2b, 2c, 2d, 2e) are arranged with respect to their relative position and position fixed to each other, and

a control device (6) which is designed to actuate the at least two light sources (2a, 2b, 2c, 2d, 2e) in such a way that in each case a light source (2a, 2b, 2c, 2d, 2e) is switched on and in time sequence the at least one further light source (2a, 2b, 2c, 2d, 2e) is switched off, and wherein the control device (6) is formed, the at least two light sources (2a, 2b, 2c, 2d, 2e) in synchronism with a picture indentation of an image Camera (4) to operate. 2. Testing device according to claim 1, wherein

at least one of the at least two light sources (2a, 2b, 2c, 2d, 2e) a

Collimator device (3, 20, 21) comprises and / or as a light-emitting diode (3 ') is formed. 3. Testing device according to claim 2, wherein

an evaluation device (7) which can be connected to a camera (4) to be tested is arranged for automatic evaluation of the camera (4)

received test light (L ₂ , L ₃ ). 4. Testing device according to at least one of claims 1-3, wherein

an optical path (L ₂ , L ₃ ) between each of a light source (2a, 2b, 2c, 2d, 2e) and the camera (4) is substantially equal.

5. Test device according to at least one of claims 1-4, wherein

the light path (L ₂ , L ₃ ) is less than 75 cm, in particular less than 50 cm, preferably less than 40 cm. Test device according to at least one of claims 1-5, wherein

the at least two light sources (2a, 2b, 2c, 2d, 2e) in a regular manner, in particular lattice-shaped, are angordnet.

Test method for a camera (4), in particular for cameras in

Driver assistance systems in a motor vehicle, preferably suitable for execution on a test apparatus according to at least one of claims 1-6, comprising the steps

Arranging the camera (4) in a holder (5),

Emitting test light (L ₂ , L ₃ ) to the camera (4) by means of at least two light sources (2a, 2b, 2c, 2d, 2e),

Recording the test light (L ₂ , L ₃ ) by the camera (4), and

Evaluation of the recorded test light (L ₂ , L ₃ ), wherein

the holder (5) and at least one of the at least two light sources (2a, 2b, 2c, 2d, 2e) are fixedly arranged relative to one another with regard to their relative position and position, and wherein the at least two light sources (2a, 2b, 2c, 2d, 2e) be actuated such that in each case in time a light source (2a, 2b, 2c, 2d, 2e) turned on and the at least one further light source (2a, 2b, 2c, 2d, 2e) is turned off and wherein the at least two light sources (2a , 2b, 2c, 2d, 2e) are operated in synchronism with an image pickup of an image of the camera (4).

Test system for an at least partially transparent object (10), comprising a test device (1) according to at least one of Claims 1-6,

a camera (4) and

an object holder (12) for an object to be tested, at least partially transparent (10), wherein the object holder (12) is arranged in the light path between the at least two light sources (2a, 2b, 2c, 2d, 2e) and the camera (4) , as well as an evaluation device (7) which is connected to the camera (4) for, in particular automatic, evaluation of test light (L ₂ , L ₃ ) recorded by the camera (4).

A test system according to claim 8, wherein

the at least two light sources (2a, 2b, 2c, 2d, 2e) and the camera to be tested (4) are arranged such that the light sources (2a, 2b, 2c, 2d, 2e) in one regular grid (100) on a recording of test light (L ₂ , L ₃ ) by the camera (4) are arranged.

10. Test system according to at least one of claims 8 and 9, wherein

the object holder (12) is arranged movable and in particular by means of the control device (6) is controllable.

1 1. A test system according to at least one of claims 8-10, wherein

the camera (4) has a dynamic range of at least 10 ⁴ , in particular at least 10 ⁵ , preferably 10 ⁷ .