DE20308365U1 - Protection device for a sunblind comprises a camera sensor system that monitors deflection of the blind due to the wind and ensures it is wound in if the wind becomes too strong - Google Patents

Abstract

Mechanically operated sunblind system has a sensor arrangement with a camera that monitors movement of the blind caused by the wind acting on it. If detected movement of the blind exceeds a threshold level the blind can be wound in. An independent claim is included for a corresponding camera sensor arrangement with an intermittently operating infrared light source.

Description

The present invention describes a protective device for awnings with the features of claim 1.

Articulated arm awnings are often used as sun protection devices. An articulated arm awning consists of a shaft with a fabric wound onto it. A front bar is attached to the end of the fabric. The front bar is pushed forwards by spring-driven articulated arms so that the fabric is always taut. If the covering fabric is unrolled by turning the shaft, the front bar moves outwards. The shading area is determined by the width of the fabric and the extension distance, which can be individually adjusted by the length of the articulated arms or the length of the fabric. The advantage of articulated arm awnings is that no support rods or supports to the ground are required, so that you have unrestricted freedom of movement under the articulated arm awning. The suspension of the fabric shaft and all necessary fastening devices are designed in such a way that the articulated arm awning can be attached on one side. Electric motors are often used to extend or retract the articulated arm awning.

However, the articulated arm awning must be protected from damage by strong wind loads when rolled out due to the one-sided fastening. In addition, extensive weather sensors are often used. In addition to damaging wind loads, the covering fabric must be protected from moisture to prevent rot and mold. Various methods are used to detect precipitation. A well-known method is the change in electrical conductivity due to moisture between electrodes. By measuring the current lighting conditions, it is possible to retract the articulated arm awning in the dark and extend it again when the sun shines.

To detect harmful wind loads, sensors are often used that work according to the principle of hemispheres with air flowing against them. An anemometer cross of this type, consisting of three to four hemispheres, is usually arranged horizontally so that primarily horizontal wind components are detected. Vertical wind components are detected with less sensitivity. If a limit value is exceeded, a corresponding retraction signal is sent to the corresponding control devices of the articulated arm awning.

The disadvantage of these anemometers is that they can often only be installed in one location that is different from the articulated arm awning. This local point measurement may not correctly record the wind conditions prevailing at the articulated arm awning.

Other suggestions (DE 100 33 831) are motion and vibration sensors to detect vibration or oscillation of the folding arm awning caused by wind loads. These sensors are mounted on the parts of the folding arm awning that move the most, for example on the front bar or on the folding arms.

These sensors must be supplied with energy and the output signal must be fed to the motor or control devices, which are usually not located in the front rods or articulated arms. The disadvantage is that the cables required for this must be laid through or on the articulated arms, which is complex and can lead to malfunctions in the articulated arms, which often buckle.

Wireless signal transmission and self-sufficient energy supplies using solar energy are an alternative, but they are technically complex and costly.

Another disadvantage is that when using motion or vibration sensors with an output signal proportional to the acceleration, high measured values can arise even though a deflection that is harmful to the articulated arm awning is not reached, for example if the higher natural frequency of the articulated arm awning results in high acceleration values with a comparatively small deflection when the extension range is small. To avoid this, an additional sensor is necessary that provides information about the extension range.

It is an object of the present invention to avoid the disadvantages of the prior art and to reduce the effort required for the installation of a wind protection device.

This object is achieved by a device having the features of claims 1-10.

It is suggested to use a camera to monitor the parts of the articulated arm awning that are moved by wind loads. The camera can preferably be mounted near the retraction motor, which is usually located in the fabric shaft, or near the control devices, i.e. where electrical supply lines are present and the switching signals for retracting the articulated arm awning are processed.

The camera is mounted on fixed support structures such as adjacent walls, ceilings or fastening devices of the articulated arm awning in such a way that little or no movement of the camera occurs due to the effects of wind.

The camera is aimed at the parts that are moved by the wind, such as the front pole. The camera's detection range is so large that all movements and all installation-dependent positions of the front pole, for example due to an inclined position of the articulated arm awning, are within the camera's detection range.

The camera is adjusted in such a way that the front bar is shown in the center of the camera receiver when it is not moving. Movements of the front bar due to wind loads lead to a deviation of the image from the resting position. The evaluation electronics generate a retraction signal when the current image position of the front bar exceeds a limit value.

A marking on the front bar improves the contrast with the surroundings.

Colored markings that differ from the color of the front bar are suitable, for example. Markings that have special geometric shapes, such as striped patterns, are also conceivable. Reflective markings such as mirrors or retroreflectors are particularly advantageous.

Good results are obtained if the marking is additionally illuminated. By using, for example, intermittent infrared light, a good signal-to-noise ratio between the receiver signal and daylight can be achieved.

An embodiment of the present invention is explained in more detail with reference to the following figures.

This shows Fig. 1: Arrangement of the camera with basic representation of the

Articulated arm awning.

Fig 2.: Structure of the camera with representation of the beam path
Fig 3.: Representation of the camera receiver with evaluation electronics

Fig. 4: Representation of the signal curve

Fig. 1 shows the measuring arrangement with camera 1 and the articulated arm awning consisting of fabric shaft 2 , covering fabric 3 , front bar 4 and an articulated arm 5.

The camera 1 is aimed at the front bar 4.

Preferably, when the articulated arm awning is in the resting state, the front bar 4 lies on the extension of the optical axis 6 of the camera 1, so that the image of the front bar is in the center of the camera receiver 7.

Due to the effect of wind 8 on the covering fabric, the articulated arm awning moves downwards from its resting state and reaches a deflection which is shown in Fig. 1 by the new position of the front pole 9 and the covering fabric 10. This results in a new image position 11 of the front pole in the receiver plane of the camera. Due to simple geometric optics, the deflection y of the front pole to be monitored is given by the distance a between the camera lens and the front pole, the distance b between the lens and the receiver and &khgr; the deflection of the front pole image from the resting state with y = &khgr; * a / b.

A housing 12 contains a lens 13, a receiver 14 and an optical filter 15. (Fig.2) An infrared radiation source 16, preferably a light-emitting diode, is arranged in the center of the lens 13.

Opposite the camera 1, when the articulated arm awning is extended, there is the front pole 4 on which a retroreflector 18 is attached. Retroreflectors have the property of reflecting incident radiation back into themselves. The radiation source 16 sends a wide-open radiation beam 19 in the direction of the front pole 4. The retroreflector 18 illuminated by this reflects the incident radiation 20 back in the direction of the camera lens 13. The lens, in the simplest case consisting of a simple lens, focuses the reflected radiation on the receiver 14. The optical filter 15 is designed in such a way that the wavelength of the infrared radiator 16 is allowed to pass through almost unhindered, while daylight is blocked.

The receiver 14 consists of a linear arrangement of several light detectors 22 (Fig. 3). Suitable detectors are photodiodes, phototransistors or CCD lines.

The detectors are aligned with the camera in the direction of movement of the articulated arm awning. These are essentially vertical movements, so that the detectors

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&phgr; φφφφ
&phgr; &phgr; &phgr;
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are arranged vertically accordingly. Other directions of movement of the articulated arm awning practically do not occur, so that the image 23 of the retroreflector 18 always covers the detector arrangement when the front bar moves.

The focal length of the lens 13 (Fig. 2) is selected so that when the articulated arm awning is half extended, a sharp image 23 of the reflector 18 is produced on the light detectors 22. Other distances between the reflector and the camera, however, are imaged blurred 24.

The distance between two adjacent detector elements is selected so that when the reflector image is sharp, at least one detector element 22 is always illuminated. If the image of the reflector is blurred 24, a larger number of illuminated and adjacent detector elements can be expected. Using a suitable calculation algorithm, for example a simple averaging, the center of the illuminated field 24 can be determined and the exact position of the reflector can be deduced.

The length of the entire detector line or the number of detector elements is chosen so that, starting from the rest position of the reflector image, a sufficient detection of a deflection of the front rod upwards and downwards is possible. In practice, a deflection of one meter of the front rod in both directions is sufficient, so that with a corresponding selection of the reduction factor of the lens, for example one hundred, a total detector length of two centimeters results.

The radiation source 16 sends light pulses in intermittent operation. The detectors illuminated in this way are read by the evaluation electronics 25 in the correct phase and frequency to the emitter pulses. The signals from the detectors 22 are amplified using conventional methods 26 and fed to a microprocessor 25, which calculates the center point from the number and position of the illuminated detector elements and determines the current deflection of the front rod from the position of this average value. If the current position exceeds a fixed limit, a retraction signal is fed to the motor.

A solution would be advantageous in which the articulated arm awning is not completely retracted when a limit value is exceeded, but first the

For example, the shading area is reduced to half of its original value.

A further advantageous embodiment of the invention is provided when the arrangement is used at the same time to detect rain or precipitation in general. Fig. 4 shows a section of the signal curve 30 of an illuminated detector element. If there is no precipitation, the signal is undisturbed in the illumination phase 31. Raindrops cause a brief disturbance of the beam profile when they fall through the beam cross-section 32. Additional short signal peaks 33 are obtained on the signals of the light receiver with a duration of a few milliseconds, which are generated by absorption and scattering of the radiation by the water drops flying past. Appropriate decoupling and amplification of this signal can serve to generate a retraction signal in order to protect the covering fabric from moisture.

Claims (10)

1. Mechanically retractable and extendable sun protection system with a sensor arrangement for determining a load due to wind action, characterized in that at least one sensor assigned to the sun protection system is a camera 1 which monitors a movement of the sun protection system occurring due to wind load. 2. Sun protection system according to claim 1, characterized in that the at least one camera 1 is attached to parts of the sun protection system that are not very moved by the action of wind or to adjacent fixed locations such as walls or ceilings and is directed at the parts of the sun protection system that are strongly moved by the action of wind, such as front bars 4 or articulated arms 5 . 3. Sun protection system according to claim 1 and 2, characterized in that the camera 1 contains a linear light-sensitive detector arrangement 14 consisting of at least two detector elements 22 , on which the parts of the sun protection system moved by the action of wind are imaged by at least one imaging optical surface 13 in such a way that the resulting movement of the image covers individual detector elements 22 or partial areas of the detector arrangement. 4. Sun protection system according to one of the preceding claims, characterized in that when a limit deflection caused by wind load is exceeded relative to a rest value, the sun protection system is caused to retract. 5. Sensor according to one of the preceding claims, characterized in that at least one light source illuminates the parts of the sun protection system moved by the action of wind, preferably with infrared light, and that this light source 16 is operated intermittently. 6. Sensor according to claim 5, characterized in that the light source is arranged centrally in the imaging optical surface 13 . 7. Sensor according to claim 3, characterized in that an optical filter 15 is arranged in front of the light receiver 14 for coupling out visible light and this filter is permeable to the radiation of the light source 16 and opaque to daylight. 8. Sensor according to one of the preceding claims, characterized in that at least one marking 18 is attached to parts of the sun protection device that are moved by wind load, which marking is projected onto the light receivers 14 and which is suitable for increasing the contrast with the environment outside the marking 18 . 9. Sensor according to claim 8, characterized in that the marking 18 is a retroreflector. 10. Sensor according to one of the preceding claims, characterized in that the partial interruptions of the light path between camera 1 and light source 16 caused by precipitation are evaluated in the electronics and upon detection of such brief interruptions 33 in the signal of the light receiver 22 , the sun protection system is caused to retract.