Patent Application
20240241543
The present invention relates to a display module according to the pre-characterizing part of claim 1, a use of the display module, a display system comprising a plurality of display modules, and a method for operating the display system.
Recent developments have brought about flexible displays that enable new applications with a bendable display. However, it is often a problem to find the right device mechanics to stabilize the flexible displays and protect them against damage during folding and rolling. In addition, special precautions must be taken if a flexible display is to be equipped with all the necessary components to be used as an independent display module.
It is therefore an object of the present invention to provide a display module with a flexible display unit, which is compact and robustly built, and at the same time flexibly bendable.
This object is solved by the features indicated in the characterizing part of claim 1. Further embodiments of the display module according to the invention, a use of the display module, a display system with a plurality of display modules, and a method for operating the display system are defined by further claims.
The display module according to the invention comprises a flexible display unit and a housing having a rear side and a front side, wherein the flexible display unit is arranged on the front side of the housing. The display module according to the invention is characterized in that the housing has a plurality of interior spaces for accommodating electronic components, that the housing is flexible at least along boundaries of the interior spaces in that the housing has recesses on the rear side which extend at least partially over the rear side, whereby the housing with the display unit is bendable within a predefined angular range along the recesses.
One embodiment of the display module according to the invention is that the recesses extend over the entire rear side of the housing.
Further embodiments of the display module according to the invention comprise that the housing is rectangular and that the recesses run parallel to side walls of the housing, preferably with the interior spaces being of equal size.
This achieves a uniform, segmental bending of the housing.
Further embodiments of the display module according to the invention comprise that the recesses form a matrix with two rows and three columns on the rear side of the housing with corresponding interior spaces, the interior spaces preferably being of equal size.
Further embodiments of the display module according to the invention comprise that the recesses have a depth corresponding to 50% to 90%, preferably 60% to 80%, preferably 75% of an average thickness of the housing.
Further embodiments of the display module according to the invention comprise that the recesses on the rear side have a width that allows a maximum bending angle of the front side of the housing of 35°.
Further embodiments of the display module according to the invention comprise that the interior spaces accommodate at least one of the following components:
Further embodiments of the display module according to the invention comprise that at least one of the following functions are realized:
Further embodiments of the display module according to the invention comprise that the maximum brightness of the display unit is 6,400 candela per square meter.
The invention further relates to a use of the display module for wearing in caps, wristbands, helmet covers, clothing, safety vests, work clothes, and other textiles that allow the attachment of a carrying bag or system. For example, the display module is worn in a pocket made of transparent or partially transparent textile, whereby the information displayed on the display module is visible through the textile.
Furthermore, the invention relates to a display system comprising
A further embodiment of the display system according to the invention is to arrange a bandpass filter in front of the image acquisition unit, whereby the bandpass filter primarily transmits infrared signals with wavelengths in the range of 700 nm to 1400 nm.
Finally, the present invention comprises a method for operating a display system, the method comprising the steps of:
A further embodiment of the method according to the invention is characterized by filtering signals with a band-pass filter prior to acquisition with the image acquisition unit, whereby the band-pass filter primarily passes infrared signals with wavelengths in the range of 700 nm to 1400 nm.
Further embodiments of the method according to the invention comprise that the step for determining the instantaneous position of the display module comprises the following:
Still further embodiments of the method according to the invention consist in that the step of determining a brightness value and/or a color value of a display module on the basis of the instantaneous position and on the basis of stored image data comprises the following:
The mentioned embodiments of the present invention can be combined in any way. Only those combinations are excluded which would lead to a contradiction by a combination.
Examples of embodiments of the present invention are explained in further detail below with reference to figures. These are for explanatory purposes only and are not to be construed restrictively. The figures show
In the illustrated embodiment of the present invention, the housing 3 is molded from a single piece, for which purpose a rubber-elastic polymer (elastomer) is used, such as a polyurethane, in which a desired hardness can be set by admixing an extender. It has been found that the desired hardness should be, for example, in the range of 60 to 100 Shore A, preferably equal to 80 Shore A.
The interior of the housing 3 according to the invention is divided into interior spaces 6, which can accommodate components such as electronic components 7 and batteries 15. Since the components 7, 15 often have a certain rigidity, the housing 3 can be bent only slightly in the region of the interior spaces 6. According to the invention, recesses 9 are therefore provided on a rear side 4 of the housing 3 in the region of boundaries 8 of the interior spaces 6 with a depth 11 which corresponds, for example, to 50% to 90%, preferably 60% to 80%, preferably 75% of a mean thickness 12 of the housing 2. The average thickness 12 results from the outer dimensions of the mounted display module 1 from the display unit 2 mounted on a front side 5 to the rear side 4 of the housing 2.
The maximum bending of the display module 1 or of the housing 3 in the area of the boundaries 8 of the interior spaces 6 or of the recesses 9 is further adjusted by a width 13 of the recess 9 (see also
As can be seen from
The display module 1 shown in the figures and thus the housing 3 are rectangular with recesses 9 running parallel to the side walls of the housing 3. In further embodiments of the present invention, it is also conceivable that the display module 1 or the housing 3 is any polygon. Accordingly, the recesses can also extend in any desired manner.
Furthermore, the recesses 9 in the housing 3 shown in
For the sake of completeness, it is pointed out that a bending of the display unit 2 is basically also possible in the other direction. Here, too, the housing 3 or its elasticity is particularly decisive for limiting such negative bending.
The display modules 1 located within the projection surface 21 form a large screen, the individual display modules 1 being picture elements or pixels of the large screen. In this regard, the projection surface 21 may be a part of a grandstand or other spectator area of an event venue, which is, for example, a sports stadium, a theater, or a concert hall. It is envisaged that each event visitor will wear a display module 1, although this is not mandatory.
The internal structure of the display modules 1 will be further explained with reference to a block diagram shown in
For correct image generation on the projection surface 21, the positions of the pixels, i.e. the display modules 1, in the projection surface 21 must be known. For this purpose, in addition to a corresponding design of the display modules, the operatively connected central computing unit 27, the data transfer unit 28 and the two image acquisition units 210 and 211 are provided. It is pointed out that it is not necessary that two image acquisition units 210, 211 be present. Embodiments of the present invention with a single image acquisition unit or with a plurality of image acquisition units, in particular with more than two image acquisition units, are also conceivable. The use of multiple image acquisition units has the advantage that the positions of the display modules 1 can be determined more robustly and reliably.
In order to keep energy consumption as low as possible or to be able to guarantee operation of the display module 1 for as long as possible, the display unit 2 is realized, for example, by means of LED (light emitting diodes) or an LED matrix. The same applies to the infrared units 18, 18′, which are realized with IR diodes.
The data transmission unit 25 can be designed as a pure data receiving unit or as a bidirectional data transmission unit and serves as a communication unit with the data transfer unit 28 (
The infrared units 18 or 18′ are essential components used to determine the position of the display modules 1. In doing so, the infrared units 18, 18′ emit an infrared signal that is not visible to the human eye with an identification code that is unique for the respective display module 1. For example, the infrared unit 9, 9′ emits infrared signals in the so-called near infrared, in which the wavelengths are in the range from 700 nm to 1400 nm. In a particular embodiment of the present invention, the wavelength is substantially 940 nm.
The infrared signals emitted by the infrared units 18, 18′ are detected by the image acquisition units 210, 211 and processed in the central processing unit 27 to identify the respective display module 1. Accordingly, the image acquisition units 210, 211 are sensitive in the respective infrared spectrum of the infrared emitters, i.e. the corresponding infrared signals of the infrared units 18, 18′ can be captured and detected in the image acquisition units 210, 211.
To further improve the sensitivity of the image acquisition units 210, 211, an optical bandpass filter 216, 217 is arranged in front of the respective image acquisition unit 210, 211—i.e. in front of their sensors—in a further embodiment of the present invention. In this way, signals which lie outside the near infrared used by the infrared units 18, 18′—such as, for example, ambient light in the visible range—are strongly attenuated, so that these visible signal components cannot saturate the sensor of the respective image acquisition unit 210, 211, whereby the weaker infrared signals can be amplified more and can thus be better evaluated. Furthermore, an improvement of the sensitivity is also obtained by the fact that the useful signal/interference signal ratio (also called signal-to-interference ratio) becomes larger by using the bandpass filter.
In order to be able to distinguish the individual display modules 1, a unique identification code is assigned to each display module 1. The identification code is embedded in a message sequence—consisting of synchronization sequence, identification code and a checksum. This enables the image acquisition unit 210, 211 to reliably determine the identification codes after receiving them from the infrared unit 18, 18′, as will become clear in the following explanations.
Each message sequence starts with the synchronization sequence, which is identical for each display module 1. The aim and purpose of the synchronization sequence is to define the start of the message sequence in order to be able to uniquely detect the start of the message sequence. The synchronization sequence is followed by the identification code, which can now also be detected after the synchronization sequence has been detected. Finally, the checksum (e.g. of the type CRC-16—“cyclic redundancy check”) follows, which allows a transmission error to be detected.
The message sequence is used to modulate the intensity of the IR diodes of the infrared unit 18, 18′. For example, on-off keying (OOK) is used as a modulation technique that represents digital data as the presence or absence of the carrier signal. The synchronization sequence is chosen so that it has excellent autocorrelation properties. This makes it easier for the image acquisition unit 210, 211 to detect the synchronization sequence within the received signal and determine the exact position, since the highest correlation value is found only at zero time shift. The length of the synchronization sequence is a tradeoff between autocorrelation performance and message duration. On the one hand, the more chips used for the synchronization sequence, the better the autocorrelation property. On the other hand, a longer synchronization sequence increases the message duration. Furthermore, the speed at which a position of a display module 1 can be calculated decreases. For example, the synchronization sequence comprises 48 chips and is created using an algorithm based on heuristic search, as described, for example, in the paper by authors M. Dimitrov, T. Baitcheva, and N. Nikolov entitled “Efficient Generation of Low Autocorrelation Binary Sequences” (IEEE Signal Processing Letters, vol. 27, pp. 341-345, 2020).
Furthermore, the number of on- and off-bits in the synchronization sequence was intentionally chosen to be equal in order to avoid correlation deviation caused by the brightness of the background. The same property is achieved for the remaining bits (i.e., the identification code and checksum) by using a technique called binary offset carrier (BOC) modulation. In BOC modulation, the data bits are multiplied by a binary carrier signal that can have two, three, or more half-periods per bit. All carriers with an even number of half-periods have the same number of on and off parts (also called chips). For example, a “BOC Sine-2 modulation” (also called Manchester code) with two half-periods per bit is used.
The identification code, for example, is specified with 24 bits, so that a total of 16 million unique identification codes can be used. Together with the 16 bits of the CRC-16 checksum, this results in a total of 24+16=40 bits or 80 chips when using BOC Sine 2 modulation. Thus the entire message consists of 48+80=128 chips.
In
The image acquisition units 210 and 211 are used to capture film sequences with, for example, a frame size of 1640×1232 pixels and a frame rate of 30 frames per second.
The frame rate of the image acquisition units 210 and 211 also determines the maximum allowable chip rate that the infrared units 18, 18′ can use to transmit its message. If all infrared units 18, 18′ are theoretically perfectly synchronized with the image acquisition unit 210, 211, a single image per transmitted chip would theoretically be sufficient.
If the infrared units 18, 18′ are not synchronized with the image acquisition unit 210, 211, the exposure time of an image with two adjacent chips may overlap, resulting in an incorrect amplitude if the two chips are unequal.
It has therefore been shown that the use of three frames per chip can be accepted at the cost of a small loss of amplitude. With a frame rate of 30 frames per second, three frames per chip and a total number of 128 chips for a message, the total duration of a message is 12.8s.
The video file 218 recorded by the image acquisition unit 210, 211 described above is processed on the central computer unit 27 to obtain a list of all valid messages from the infrared units 18, 18′ present in the video file 218. This is done in several steps I to III, which are explained below with reference to
The first step I is to extract all frames from the video file 218 and store them as a multi-dimensional array 219 (“array of frames” or “sequence of frames” or “series of frames”). This facilitates calculations applied to all frames. In order to reduce the memory requirement, each individual image can, for example, be reduced in size by reduction (so-called “pixel binning”).
In a simplified embodiment of the present invention, the video sequences captured by the image acquisition units 210, 211 are processed directly into the multi-dimensional rows 219, i.e., storage of the video sequences in the aforementioned video files is not performed.
The second step II is to search for a synchronization sequence at each pixel position. This is done by cross-correlating the synchronization sequence with the values of a pixel along all frames. Here, the calculation of the cross-correlation is proposed using the Fast Fourier Transform (FFT), since it speeds up the calculations considerably. Then, the highest absolute correlation value of each pixel is compared with a threshold value corresponding to the correlation value of a pixel with the minimum allowed signal amplitude. In this way, only the image points with a higher probability are considered.
In this approach, it is assumed that the display module 1 remains in approximately the same location (i.e., equally illuminated pixels) for the duration of a message sequence. The result of this processing step is a list of pixels that can be considered as possible candidates with a valid message sequence.
In the third step III the message sequences are extracted and decoded to check the checksum for all message sequences. As a result, a list is returned containing the pixel coordinates, the message sequences and the estimated signal amplitude for each pixel.
Once the pixel coordinates of the detected infrared units 18, 18′ are known, they can be transformed into position coordinates within the projection surface 21, whereby the underlying geometric problem in the projection surface 21 under consideration can often be simplified, because after all the possible positions of the display modules 1 are limited to positions in a stage where spectators can be present. For example, spectators can move freely on a stand, which means that the whole or at least a part of the stand can be considered as a geometric plane. Thus, the transformation problem is to relate a point on the image plane (within the image acquisition unit 210, 211) to a point on the plane of the projection surface 21. In image processing, the relationship between any two planes in space is called homography, which is explained, for example, in “Basic Concepts of the Homography explained with Code” (OpenCV, downloadable at: https://docs.opencv.org/4.x/d9/dab/tutorial_homography.html).
The position (x, y) of one plane can be transformed into the position (x′, y′) of the other plane with the homography matrix M.
The homography matrix H can be calculated using at least four known reference points 213, 214, 215, 215a between the two planes. In practice, for example, the four corners of a projection surface 21 may be considered as reference points 213-215, 215a and may be temporarily equipped with infrared units 18, 18′, for example. The known positions of the reference points 213-215, 215a and the image point coordinates from the image can then be used to compute the matrix H. As long as the respective image acquisition unit 210, 211 is aligned in the same way, the homography matrix remains valid and the reference points 213-215, 215a are no longer needed.
It has been shown that the display system according to the invention provides extremely robust and accurate results with regard to the position of the movable display modules 1. Positional inaccuracies of 4 cm on average could be determined over larger distances, which is extremely small considering an average distance between two display units 1 of 60 cm. Accordingly, with the display system according to the invention, large screens can be realized without further ado at large events. It has proved particularly advantageous if the display modules 1 with all their components are integrated in a cap, in particular an umbrella cap, and are thus handed over to the spectators to be worn during the event.
The electronic components 7 in the display module 1 are intended to realize a number of functions. Together with the batteries 15 or accumulator packs, this results in an extremely powerful and independent display module 1 which can be used for a large number of applications.
The following functions can be implemented individually or in combination in the electronic components together with suitable software, which is available as standard:
The display module 1 according to the invention can be used for wearing in caps, wristbands, helmet covers, safety vests, work clothes, just to name a few applications. In this context, the display module 1 can also be worn behind textiles, because the extremely powerful display unit 2 can achieve a luminance of up to 6400 nits, which in SI units corresponds to a value of 6400 candela per square meter (cd/m2).
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/EP2023/051140 | Jan 2023 | WO | international |
| 23194322.6 | Aug 2023 | EP | regional |
This application claims the benefit of EP Application No. 23194322.6, filed Aug. 30, 2023, and International Application No. PCT/EP2023/051140, filed Jan. 18, 2023, and which claims the benefit of the contents of which are incorporated by reference.
