CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to European Patent Application No. 20 183 454.6, filed on Jul. 1, 2020, the entirety of which is incorporated herein by reference.

BACKGROUND

Technical Field

The present disclosed subject matter relates to a display device comprising at least a first and a second panel, each of which comprises luminous elements arranged in rows and columns and which can be aligned with one another to form a gap running parallel to the columns, and at least one connecting element for holding the panels in their aligned position. The disclosed subject matter further relates to a panel, particularly for such a display device, and a method for controlling such a display device.

Background Art

Modular display devices of this type are used to form a common flat or curved image area from a plurality of aligned panels and to reproduce image or video signals by means of their luminous elements (“pixels”). Light-emitting diodes (LEDs), for example, made of organic materials (OLEDs), are often used as luminous elements. Due to their modularity, there is a wide range of applications from large stationary video walls in stadiums or on buildings to mobile large screens temporarily set up on site for events to foldable TV, computer or mobile phone screens that can be stowed away to save space in the folded state, for example, as disclosed in the documents EP 2 443 621 B1, EP 2 568 464 B1 or AT 515 846 B1.

In all of these applications, gaps between the panels can significantly impair the image quality when the gap width and the variation thereof along the gap cause uneven luminous element spacings and therefore disturbing irregularities in image brightness that are perceptible to the human eye. For example, gaps which fall below or exceed a regular luminous element spacing appear lighter or darker to the viewer than the rest of the image area.

However, setting and maintaining the correct gap between two panels, that is, ensuring a regular luminous element spacing across the panel boundaries, is difficult in practice due to component tolerances, component aging, thermal expansion and wind. A certain minimum gap width is often required not only to accommodate component tolerances and thermal expansion, but also to prevent the luminous elements from hitting one another at the gap in the event of vibrations or wind, which can lead to damage to the luminous elements close to the gap. Especially in the case of high-resolution display devices having luminous element spacing in the sub-millimeter range, the gap width can often not be reduced to the same extent, be it because of production-related component tolerances or necessary minimum housing wall thicknesses of the luminous elements, so that excessive gaps here are also due to the design.

In the case of mobile display devices for the event area, which are frequently set up and dismantled, different gap widths arise between the panels each time they are set up again, for example, when they are plugged together or screwed. Particularly in the case of foldable display devices, for example, for the home cinema sector or for portable electrical devices, a slightly changed gap width is also always created with each unfolding due to the necessary bearing clearance. This effect can intensify over time due to aging phenomena such as the bearings of the folding mechanism wearing out or knocking out.

BRIEF SUMMARY

The goal of the disclosed subject matter is to create display devices, panels and control methods therefor which overcome the mentioned disadvantages of the known art and contribute to decreasing the visibility of construction-related or operational gaps between the panels.

This goal is achieved in a first aspect of the disclosed subject matter with a display device, comprising

at least a first and a second panel, each of which comprises luminous elements arranged in rows and columns and which can be aligned with one another to form a gap running parallel to the columns,

at least one connecting element for holding the panels in their aligned position,

a measuring device which is configured to determine, for a row of the first panel, a width of the gap at the level of said row, and

a driver which receives a signal to be displayed and is connected to the measuring device and at least one luminous element of said row, which driver is configured to control said luminous element as a function of both the signal and the gap width determined for said row.

It is to be understood that the panels considered here can lie next to one another as well as one below the other, wherein, in the first case, the rows run horizontally and in the second case vertically, that is, in both cases normal to the gap.

The display device according to the disclosed subject matter uses a psycho-optical effect (“optical illusion”) to dynamically correct the visibility of the gaps between the panels: On the basis of an individual measurement of the gap width between two panels by means of the measuring device, the driver scales the image or video signal to be reproduced by the luminous elements so that the physically existing gap between the two panels is less perceived by the viewer. For example, when the gap width exceeds the average luminous element spacing, that is, when the gap is too large, the driver can increase the brightness of luminous elements close to the gap in order to make the otherwise darker gap no longer perceptible to the human eye as dark. To do this, the driver multiplies, for example, the video signal for the luminous element(s) closest to the gap in a row by a factor greater than one, for example, to lengthen the pulse duration of pulse-width modulated luminous elements or to increase the voltage applied to voltage-controlled luminous elements, or the driver, when the gap is too small, decreases the brightness of the luminous element(s) close to the gap in order to make the gap, which otherwise appears brighter, less noticeable to the viewer.

Generally speaking, the driver can be configured to increase the brightness of at least one luminous element closer to the gap relative to the brightness of at least one luminous element further away from the gap, when the determined gap width is greater than an average distance between the luminous elements in said row, and to decrease said brightness when the determined gap width is smaller than the average distance between the luminous elements in said row. The increase in brightness of the luminous elements close to the gap, which is required to compensate for perception of the overly large gap, can thus be achieved in three ways: by increasing the brightness of the luminous elements close to the gap, by reducing the brightness of the luminous elements distant from the gap, or both; and all this vice versa to compensate for perceptions of an overly small gap. Overdriving of the luminous elements can also be prevented by appropriate selection among these options, as is described in more detail later.

The gap compensation according to the disclosed subject matter is suitable for all types of display devices composed of panels. The connecting elements between the panels can accordingly be rigid or articulated, detachable or non-detachable. In a first embodiment of the disclosed subject matter, the connecting element for holding and aligning two panels is, for example, a common carrier on which the panels are mounted, or one or more tabs, adhesive, riveted or welded seams, via which the panels are connected to one another.

The present disclosed subject matter is particularly advantageous for display devices having movable and/or detachably couplable panels, for example, foldable or pluggable panels. In a second embodiment of the disclosed subject matter, the connecting element is therefore a joint, via which the panels can be pivoted between the aligned position and a folded position. For example, the display device can be folded up like a fan-fold, that is, the panels can be folded onto one another in a zigzag shape by means of the joints, as described in the documents EP 2 443 621 B1, EP 2 568 464 B1 and AT 515846 B1.

In a further third embodiment of the disclosed subject matter, the connecting element is a coupling via which the panels are detachably connected. The coupling can, for example, be a plug-in or screw coupling directly between the panels, or a common carrier with which the panels can be detachably coupled. In the case of transportable display devices for the event area, the panels can easily be detached from one another, temporarily stored and transported individually in a space-saving manner and then coupled together for reconstruction.

The measuring device can be used once after each (re-)alignment of the panels to determine the current gap width(s), on the basis of which the driver controls the luminous elements to reduce the gap visibility. In order to also compensate for temporal changes in the gap width during operation, for example, due to thermal expansion, component aging and deformation, weather influences, etc., it is particularly advantageous when the measuring device is configured to continuously determine said gap width during operation of the display device. “Continuously” in this context means that the measuring device determines the gap width continuously or at—e.g., regular—time intervals, for example, every second, minute, hour, etc., for one or more rows. The driver then controls the luminous elements on the basis of the currently determined gap width, so to speak “dynamically” according to the relative position and relative movement of the panels in order to achieve the described reduction in gap visibility.

In the simplest case, the measuring device can comprise only one sensor which determines a single, uniform gap width for all rows of the display device. However, the measuring device optionally comprises at least two sensors spaced apart from one another in the longitudinal extension direction of the gap, of which the first measures a first width of the gap at the level of the first sensor and the second measures a second width of the gap at the level of the second sensor, wherein the measuring device is configured to determine the gap width at the level of said row on the basis of the measured first and second widths. In this way, a gap that widens or narrows over the longitudinal extent of the gap, for example, between panels that are misaligned at an angle, can be measured. From the measured values of the two sensors, the measuring device can then determine the respective gap width for each row lying between or outside the two sensors through appropriate interpolation or extrapolation.

Each sensor can either be arranged entirely on the one panel or entirely on the other panel in order to measure the gap width at the level thereof, or it can consist of two sensor parts lying opposite one another on both sides of the gap and distributed on the panels, which sensor parts measure the gap width between one another. In the case of sensors lying entirely on one or the other panel, when using two sensors, the one sensor could be arranged on the first panel and the other sensor on the second panel in order to reduce the number of sensors required per panel.

In order to be able to determine any profiles of the gap width beyond a linear gap width change, the measuring device can also comprise three or more sensors in further embodiments and use the gap widths measured by said sensors for a corresponding curve interpolation or extrapolation to determine the gap width at the level of each row.

In a first variant of the disclosed subject matter, each panel of the display device can be equipped with its own measuring device and its own driver and independently carry out said brightness control of its luminous elements to compensate for the perception of the gap. The brightness control can take place either on one side, wherein each panel is associated with its own gap that is perception-compensated only by means of its luminous elements, for example, the gap to the left of the panel, or on both sides, wherein one gap is associated with a plurality of panels, by means of the luminous elements of which the gap is perception-compensated. In an alternative, second variant of the disclosed subject matter, two adjacent panels can share a measuring device, that is, the measuring device of the first panel is configured to also determine a width of the gap at the level of said row for at least one row of the second panel, and said driver of the first panel, or a corresponding further driver of the second panel, is configured to control at least one luminous element of said row of the second panel as a function of the gap width determined therefor. The number of components can thereby be reduced. In addition, when controlling the luminous elements of both panels, that is, on both sides of the gap, the brightness reserve (“headroom”) required to avoid overdriving the luminous elements close to the gap if the gaps are too large can be halved and, conversely, the drive range of all luminous elements that can be used to reproduce the video signal can thus be increased.

The luminous elements of a panel can be controlled as a function of the width of only a single gap, particularly the luminous elements close to the gap and/or in a panel on the edge of the display device which comprises only one adjacent panel. In panels having more than one adjacent panel, that is, when the display device comprises at least a “third” panel which can be aligned with the first panel to form a further gap, the measuring device can optionally also be configured to determine a width of said further gap, and the driver can be configured to control said luminous element also as a function of the determined width of the further gap. Said further gap can either run parallel to the rows or parallel to the columns of the first panel, that is, the first, second and third panels can be arranged linearly next to one another or in an L-shape (“across the corner”). Controlling the luminous elements of the middle panel of such a group of three as a function of the two gap widths makes it possible to simultaneously both to reduce the visibility of both gaps and to maximize the brightness of the luminous elements for the reproduction of the image or video signal. For example, when the gaps are too large, the brightness reserve that is required to increase the brightness of luminous elements close to the gap to reduce their visibility can be determined on the basis of the largest of all determined gap widths in order to simultaneously reduce the gap visibility, achieve maximum brightness for video signal reproduction and prevent overdriving of luminous elements close to the gap.

The display device can comprise further panels that can be aligned with the first panel, for example, a fourth, fifth, etc., whereby the visibility of all further gaps thus formed can be reduced by determining the respective gap widths and controlling the luminous elements on the basis of the determined gap widths.

In a second aspect, the disclosed subject matter provides a panel, particularly for the display device described above, which comprises luminous elements arranged in rows and columns and can be aligned with at least one second panel, to form a gap running parallel to the columns, which panel is characterized by a measuring device according to the disclosed subject matter which is configured, for a row of the panel, to determine a width of the gap at the level of said row, and a driver that receives a signal to be displayed and is connected to the measuring device and at least one luminous element of said row and is configured to control said luminous element as a function of both the signal and the gap width determined for said row.

The panel of the disclosed subject matter enables strict modularization of the display device. A plurality of panels of the same type can be put together like building blocks. As a result, a wide variety of display devices can be built cost-effectively from the same standardized modules, namely panels and respectively associated connecting elements, measuring devices, sensors and drivers, which considerably simplifies production, storage, sales and assembly.

In one embodiment of the panel, the measuring device comprises at least a sensor which is integrated into a peripheral side of the panel facing the gap. The integration of the sensor into the peripheral side of the panel enables particularly small gap widths. In addition, the integration protects the sensor from damage during storage and transport of the panels and when folding, plugging together or assembling the display device.

With regard to further configurations and advantages of the panel according to the disclosed subject matter, reference is made to the above statements on the display device according to the disclosed subject matter.

In a third aspect, the disclosed subject matter also provides a method for controlling a display device having at least a first and a second panel, each of which comprises luminous elements arranged in rows and columns and which can be aligned with one another to form a gap running parallel to the columns, which method is characterized according to the disclosed subject matter by:

determining, for a row of the first panel, a width of the gap at the level of said row; and

controlling at least one luminous element of said row as a function of both a signal to be displayed and the gap width determined for said row.

With regard to the advantages and further embodiments of the method according to the disclosed subject matter, reference is again made to the above statements on the display device according to the disclosed subject matter.

