Device and method for electronic evaluation of hits

0001The invention relates to a device and a method for detecting the position of an object flying through an evaluation surface, in particular a projectile or arrow, wherein the device and the method can be used in particular for shooting ranges, especially for sport shooters.

0002In the <patcit id="pcit0001" dnum="DE4415944A1"><text>DE 44 15 944 A1</text></patcit> describes an electronic target and a method for evaluating it, a light source illuminating a focusing screen via optics. The optics represent a shadow projection of a projectile on the focusing screen onto a target sensor. The target sensor exchanges the information obtained with a system control by means of a line. Slotted disks are introduced into the beam path of the light source.

0003A disadvantage of this method is that the light signal is weakened by the additional screen or screen, which can give rise to an increased technical outlay given the short exposure times required. In addition, the distance between the camera and the measuring field must be observed, which results in a large design. In addition, the point light source is expanded by the lens, which additionally requires a further distance between the light source and the evaluating surface with the lens arranged in between.

0004<patcit id="pcit0002" dnum="DE1917138A1"><text>DE 19 17 138 A1</text></patcit> shows a photoelectronic arrangement for position detection of rapidly moving objects, in which two light curtains, in which a moving light beam in one plane creates a gapless light surface, are arranged such that the two light surfaces lie in one plane and cross each other, and in which within the the passage points of the objects mentioned lie from the two light surfaces.

0005<patcit id="pcit0003" dnum="DE3132172A1"><text>DE 31 32 172 A1</text></patcit> relates to a device for determining the position of the piercing point of an object, for example a projectile fired. For this purpose, a measuring area is designed so that it can be monitored by two optical imaging systems which are equipped with photo detector lines. The penetration point of a projectile causes shading of one or more photodetectors and can thus be determined on the basis of the output signals of the photodetectors. Illumination devices which illuminate the measuring range are assigned to the imaging systems. An evaluation circuit connected downstream of the photodetectors is designed in such a way that a reduction in the output signal of the detectors is sensed and evaluated when the projectile flies through the measuring range.

0006<patcit id="pcit0004" dnum="US6717684B1"><text>US 6 717 684 B1</text></patcit> shows a device for target counting with an elongated back-reflecting component, two light sources, each a sensor for a light source and a processor. The light beams from the two light sources intersect and define a target area. The sensor of the first light source generates a first signal which is dependent on a first position of a first disturbance in the illumination of the back-reflecting component. The second sensor generates a second signal, which is dependent on a second position of a second interference in the illumination from the back-reflecting component. The processor is programmed to determine a position of the object in the target area based on the first position of the first interference of the illumination and the second position of the second interference of the illumination.

0007<patcit id="pcit0005" dnum="EP0121840A"><text>EP 0 121 840 A.</text></patcit> shows a device for determining the position of an object within a field of view, for example a screen, in which point radiation sources are arranged at a distance from one another on the circumference of the field of view. Furthermore, the circumference of the field of view is provided with a back-reflecting surface, which reflects the radiation emanating from the point-shaped radiation sources back to these radiation sources. Radiation receivers are each arranged adjacent to the radiation sources, so that they lie in the radiation reflected back from the back-reflecting surface. If an object is arranged in the field of view, then this object is imaged on the radiation receivers. The coordinates of the object within the field of view can be calculated from the position of this image on the radiation receivers.

0008<patcit id="pcit0006" dnum="WO9507471A"><text>WO 95/07471 A</text></patcit> describes an optical system and method for detecting the presence and position of an at least stationary or moving object in a field. The optical system has at least one light source for generating a light beam, the light beam being scanned by at least one first reflective surface to generate a plurality of the light beams. The light beams are overlaid on the field by at least one second reflecting surface and their intensity is measured by at least one detection means.

0009One object of the invention is to implement a device and a method for detecting the position of an object, in particular a projectile or arrow, flying through an evaluation surface, which have a very compact design and a high evaluation accuracy.

0010The object is achieved according to the features of the independent claims. The dependent claims show advantageous embodiments and further developments of the invention.

0011The device according to the invention and the method according to the invention can be used for shooting ranges, especially for sports shooters. The projectile or arrow can penetrate two light curtains which are preferably arranged orthogonally (90 °) to one another. The two light curtains can be arranged one above the other or overlapping in the flight direction of the shot, so that no parallax errors can occur. That of, for example, rod-shaped or Light emitted in the form of strips can be forwarded to a respective camera device via a respective lens, wherein the camera device can contain, for example, a line scan camera. A lens of this camera can form a telecentric lens together with the associated lens. Furthermore, the beam path directly behind the lens can be redirected twice, for example by 90 °, so that the camera device can be arranged on the same side as the light source, as a result of which a very compact design can be achieved.

0012According to the invention, the device for optically detecting the position of an object flying through an evaluation surface, in particular a projectile or arrow, has at least one light source emitting a light strip which emits light into an evaluation plane, at least one lens through which the light emitted by the light source is guided at least one camera device into which the light is guided after the lens and / or an evaluation device, which evaluates a signal from the camera device and outputs a position of the object. The method according to the invention can use an evaluation device to determine position values ​​which correspond to x-axis values ​​and y-axis values, from which a position in the x and y directions of an object passing through the evaluation plane is determined.

0013Furthermore, at least one deflection device is provided, which is arranged behind the lens and deflects the light in such a way that it is guided again through the lens, the light after the lens being in a return plane. Instead of using one lens that is irradiated twice, two lenses can also be used, for example the light radiating to the deflection device is guided through the one lens and the light returned by the deflection device is guided through the other lens.

0014A very compact device can be achieved by providing the deflection device and using the lens twice. In addition, position values ​​can also be used to further increase the detection accuracy, which are obtained when the object flies through the return plane. Furthermore, on the basis of the number of images captured by the camera device, on which a shadow of the object can be seen, a conclusion can be drawn about a speed of the object, wherein the speed can be used as a plausibility check for the detected signal. This makes it possible to distinguish the fast-flying projectiles to be detected from other bodies and particles which may move through the detection device, in order to thereby filter out false signals. Two light sources, two lenses, two deflection devices and two camera devices can be provided. The light emitted by the two light sources can preferably be arranged at an angle of essentially 90 ° to one another. The light emitted by the light sources can penetrate the evaluation plane uniformly with homogeneous light and strikes a respective lens on the other side. From the respective lens, the light strikes the respective deflection device, which then in turn reflects the light through the respective lens back in the return plane onto the respective camera device. The lenses and the objects of the camera device are designed in such a way that a telecentric lens is obtained, ie that the opening angle of the lenses is corrected by the lenses in such a way that a parallel beam path results. This applies to the x and y or the horizontal and vertical directions (see<figref idref="f0001">Fig. 1</figref>).

0015The light emitted by the two light sources can preferably overlap in the evaluation plane and / or in the return plane. However, it is also possible for the light from the two light sources to be emitted in different planes. The same applies to the light in the return level, which can also be sent back to different levels. However, the distance between these different levels should only be small so as not to reduce the evaluation accuracy too much.

0016The disadvantage of the large size described in the aforementioned prior art results from the fact that, depending on the focal length of the lens, the distance from the camera to the converging lens must be approximately the same size as the firing field to be evaluated, i.e. the complete apparatus would be at least four times the area of ​​the firing field to be evaluated exhibit. According to the invention, this disadvantage can be eliminated in that the light behind the converging lens is deflected by, for example, two mirrors. These mirrors in the deflection device create two light curtains, a parallel, telecentric light curtain and a non-telecentric light curtain. The side facing the shooter has the telecentric area. The twice deflected beam path in the return plane can have an angle which corresponds to the opening angle of the lens of the camera device.

0017The distance between the telecentric and the non-telecentric light curtain should be at least so large that the projectile does not fly through both light curtains during an integration time of a sensor of the evaluation device, i.e. the projectile flying through (the moving object) on the camera chip creates a shadow twice in succession, whereby only the first (telecentric) light curtain in the evaluation level is of primary importance. As already briefly explained above, the second light curtain can also be used to increase the measuring accuracy. However, this is only possible if the projectile is in the center area of ​​the device.

0018It is also advantageous to guide the beam path twice through the corresponding lens. This enables the necessary focal length of the lens to be doubled, ie the lens thickness can be almost halved.

0019Furthermore, the converging lens can be designed as a Fresnel lens. The deflection mirrors mentioned above can also be replaced by a 90 ° prism with total reflection.

0020According to a further possibility, the two deflecting mirrors can be made concave in order to achieve the telecentric effect of the lens.

0021In order to make the light emitted from the light source to the lens as homogeneous as possible, a scattered light means can also be provided. This scattered light means can be provided in the beam path after a transparent rod, can be integrated into the rod, and / or can be realized by the rod. The rod can be provided in the beam path after light-generating elements, for example light-emitting diodes. The light source can be the light-generating elements, the rod and / or the or contain the scattered light.

0022The invention will now be explained in more detail using exemplary and schematic figures.

0023Show it<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> 1 shows a schematic view of individual components of the invention with a converging lens,</li><li><figref idref="f0002">Fig. 2</figref> 1 shows a schematic view of the invention with a Fresnel lens,</li><li><figref idref="f0003">Fig. 3</figref> and <figref idref="f0004">3a</figref> schematic views of the invention with two beam paths, and</li><li><figref idref="f0005">Fig. 4</figref> a schematic section through the device according to the invention in one direction (x or y direction).</li></ul>

0024In the <figref idref="f0001">Fig. 1</figref> A preferably linear or rod-shaped light source 1 is shown, which emits its light in the direction of the lens. The light source 1 can be designed such that the light is emitted as a light strip. The angle of the light 2 is changed by a converging lens 3 or a parabolic mirror 23, 24 such that a beam path 10 is obtained which corresponds to an opening angle of a lens 5 of a camera device 4. The objective 5 focuses the incident light on a position-sensitive photosensitivity area of ​​a preferably semiconductor component or sensor 6, such as a CCD or C-MOS line sensor. In the<figref idref="f0001">Fig. 1</figref> only one beam path is shown schematically in one direction (x or y direction of the detection device).

0025In the <figref idref="f0002">Fig. 2</figref> is different from <figref idref="f0001">Fig. 1</figref> instead of the converging lens 3, a Fresnel lens 7 is shown.

0026The converging lens 3 and / or the Fresnel lens 7 together with the camera device 4 form a telecentric lens which has a parallel beam path on the respective left side of the lens 3, 7 and a triangular beam path on the right side.

0027In the <figref idref="f0003">Fig. 3</figref> an advantageous embodiment of the invention is shown for space optimization. To optimize space, the beam path behind the lens 3 is deflected via, for example, two mirrors 8, 9 of the deflection device and reflected back in the direction of the light source 1 against the parallel light curtain (primary light curtain). The reflected light curtain 10 is at a predetermined distance from the primary light curtain 2. The primary light curtain 2 is located in an evaluation level 16 and the reflected light curtain 10 is located in a return level (see <figref idref="f0005">Fig. 4</figref>).

0028In the <figref idref="f0005">Fig. 4</figref> is the basic structure of an inventive. Detection or scanning unit shown in one direction (x or y direction). Light is emitted via, for example, light-emitting diodes 18, which can be arranged in a row. This light strikes an at least partially transparent, preferably rotationally symmetrical rod 19 which focuses the light in the direction of the lens. The rod can be made of glass, for example.

0029In order to make the light emitted to the lens as homogeneous as possible, a scattered light means can also be provided. This scattered light means can be provided in the beam path after the rod 19 or can be integrated into the rod 19 and / or realized by the rod 19. The scattered light can be made of milky, transparent material. The features of the light source explained above can be used for all the embodiments described, in particular also for realizations of the invention without a deflection device.

0030The rod 19 transmits the beam path 2 in the evaluation plane 16 to the converging lens 7. The light runs from the collecting lens 7 to the deflection device 8, 9, which consists of a mirror 8 and a mirror 9. At this point it should be noted that a Fresnel lens 7 can also be provided instead of the converging lens 3. Behind the corresponding lens 3, 7 is the mirror 8 which is inclined by 45 ° and which deflects the incident light onto a second mirror 9. This mirror is also inclined at 45 °. The light is guided through the two mirrors 8, 9 of the deflection device into a return plane 17, which can be parallel to the evaluation plane 16. The deflected light curtain in the return plane 17 is at such a distance from the first parallel light curtain 2 in the evaluation plane 16 that during the exposure time of the camera device 4 a projectile 20 only passes through the first light curtain 2 and has not yet reached the second light curtain 10. The distances between the two light curtains 2, 10 or the evaluation level 16 and the return level 17 are preferably between 10 and 30 mm. Exposure times can be, for example, 60,000 frames / s.

0031When the projectile 20 passes through the evaluation plane 16, the camera device 4 can detect a corresponding shadow. This shadow can then be detected by an evaluation device. Since the in the<figref idref="f0005">Fig. 4</figref> shown arrangement is provided both in the x-direction and in the y-direction, an accurate position detection of the projectile 20 or the moving object is possible.

0032The optical elements of the device according to the invention can be arranged in an x ​​and y direction or in a vertical and horizontal direction. The first light source 1 and a second light source emit their light in the x and y directions. These parallel beam paths meet corresponding converging lenses 3 on the other side of an active evaluation surface. Fresnel lenses 7 can also be used instead of the collecting lenses 3 shown. The active evaluation area is located in the intersection of the beam paths 2.

0033The light is reflected back by the mirrors 8, 9 of the deflection device and directed back in the direction of the respective light source 1. However, the light is returned in a return plane 17 that is different from the evaluation plane 16. The lenses 3 and 7 provided are designed such that the light path passes the corresponding lens twice. As a result, the necessary focal length of the corresponding lens is twice as large, i.e. that is, the lens can be made about half as thick. The light 10 reflected back by the aforementioned lenses in the direction of the camera device 4 is arranged behind the parallel (telecentric) light field, as seen in the firing direction. The projectile or the moving object penetrates the returning light curtain 10 only after the hit position has been evaluated.

0034It should be expressly mentioned here that the use of parabolic mirrors is possible instead of the aforementioned lenses or Fresnel lenses and mirrors. This possibility is in the<figref idref="f0004">Figure. 3a</figref> shown. Here, two parabolic mirrors 23, 24 are provided, which can also be aligned twice at 45 ° to one another, so that here too the second light curtain is reflected in the return plane 17 behind the first primary light curtain 2. Would in the<figref idref="f0005">Fig. 4</figref> the two mirrors 8, 9 are made parabolic, the converging lens 3, 7 could be omitted, as in the <figref idref="f0004">Fig. 3a</figref> shown. The radii of the concave mirror (concave mirror) can be determined using the following formula:<maths id="math0001"><math display="block"><mi mathvariant="normal">f</mi><mo mathvariant="normal">=</mo><mi mathvariant="normal">r</mi><mo mathvariant="normal">/</mo><mn mathvariant="normal">2</mn></math><img file="EP1892495B1_D0001.tif" /></maths> f stands for the focal length of the light and r for the radius of the mirror.

0035A projectile 20 passing through the primary light curtains 2 results in an x ​​and y position in the corresponding camera devices 4, since a respective shadow is detected in both camera devices 4. This shadow can be evaluated accordingly in order to output corresponding position signals.

0036An example of an electrical control of the device according to the invention has an evaluation device or a controller on which the light intensity of the linear light sources 1 is set via two corresponding outputs. Furthermore, sensors 6 are read in by the controller. These sensors 6 are preferably line sensors. Pixel and line clock signals are still generated by the controller. The light sources 1 are controlled by the signals returned by the line sensors 6, so that closed control loops are created. The two sensors 6 are illuminated uniformly by the optical arrangement. If, for example, a projectile 20 flies through the two light curtains 2, corresponding sectors on the sensors 6 are darkened. The x and y values ​​calculated in this way by the controller are forwarded via a network, for example to a visualization which can be arranged during the protection. Furthermore, the signals can be received directly with a central computer, so that, for example, a competition can be evaluated online. A data transmission can advantageously take place through a BUS system or a radio network. In addition, a coding device can be provided which allows a data record to belong to a specific shooting range if several corresponding devices are provided.

0037The aforementioned features and embodiments can be combined with one another in any manner.