Classifications

• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
  • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
  • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
  • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/14—Digital output to display device ; Cooperation and interconnection of the display device with other functional units
  • G06F3/1423—Digital output to display device ; Cooperation and interconnection of the display device with other functional units controlling a plurality of local displays, e.g. CRT and flat panel display
  • G06F3/1446—Digital output to display device ; Cooperation and interconnection of the display device with other functional units controlling a plurality of local displays, e.g. CRT and flat panel display display composed of modules, e.g. video walls
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/14—Digital output to display device ; Cooperation and interconnection of the display device with other functional units
  • G06F3/147—Digital output to display device ; Cooperation and interconnection of the display device with other functional units using display panels
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
  • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
  • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
  • G09F9/302—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements characterised by the form or geometrical disposition of the individual elements
  • G09F9/3026—Video wall, i.e. stackable semiconductor matrix display modules
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/02—Composition of display devices
  • G09G2300/026—Video wall, i.e. juxtaposition of a plurality of screens to create a display screen of bigger dimensions
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/02—Improving the quality of display appearance
  • G09G2320/0233—Improving the luminance or brightness uniformity across the screen
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/02—Improving the quality of display appearance
  • G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/04—Maintaining the quality of display appearance
  • G09G2320/041—Temperature compensation
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/04—Maintaining the quality of display appearance
  • G09G2320/043—Preventing or counteracting the effects of ageing
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/06—Adjustment of display parameters
  • G09G2320/066—Adjustment of display parameters for control of contrast
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/06—Adjustment of display parameters
  • G09G2320/0666—Adjustment of display parameters for control of colour parameters, e.g. colour temperature
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2340/00—Aspects of display data processing
  • G09G2340/04—Changes in size, position or resolution of an image
  • G09G2340/0407—Resolution change, inclusive of the use of different resolutions for different screen areas
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2360/00—Aspects of the architecture of display systems
  • G09G2360/02—Graphics controller able to handle multiple formats, e.g. input or output formats
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
  • G09G5/18—Timing circuits for raster scan displays

Definitions

• the present invention concerns a method for displaying images on a display device, as well as a display device for realising this method.
• the invention concerns display devices comprising a display which consists of several display units, whereby these display units are driven by means of a general processing unit, as well as by means of individual processing units per display unit.
• the invention is particularly meant for display devices comprising display units whereby the image is reproduced by means of what are called LED's (Light Emitting Diodes).
• an LED wall can so to say be built in this manner. It is also known that, by building the LED wall from groups of LED's of different colours, in particular red, blue and green, by appropriately adjusting the intensity of the different LED's, it is possible to obtain various global colour effects. Also, by means of an appropriate control of the LED's, it is possible to reproduce moving images in colour, for example video images, on the LED wall.
• Such display devices can be used for different purposes, for example for displaying images in stadiums, information and/or publicity in public buildings, such as for example airports, stations, etc.
• a display device with active modules is known from US 5.523.769. Data are exchanged here between a general processing unit and one central, individual processing unit, which further communicates with the other individual processing units. The different processing units can also communicate among themselves .
• This known device is disadvantageous in that a large number of mutual data exchanges are required, so that the system is very restricted as far as calculation possibilities are concerned.
• the invention aims a method for representing images on a display device of the above-mentioned type, whereby this method allows for a smoother data processing than according to the methods known until now.
• the method of the invention is designed for LED screens, but it can also be applied in a more general way in other display devices, such as CRT projectors and the like.
• the invention concerns a method for displaying images on a display device, characterised in that use is made of a display device comprising at least a general processing unit, a display consisting of several display units and an individual processing unit per display unit, whereby, in order to display the images, data concerning the image to be displayed are transmitted from the general processing unit to the individual processing units in the form of a data stream, in that there is a control communication between the general processing unit and each of the individual processing units in the form of control signals, and in that data from the data stream are collected at every individual processing unit as a function of the control signals transmitted to the individual processing units.
• every display unit can work independently of the other ones, requiring no communication with a central individual processing unit.
• no mutual data exchange is required between the individual processing units, there will be less data transmission, making more calculation time and calculation capacity available for processing the signals in the individual processing units.
• a distributed signal processing will be provided for according to the invention between the general processing unit on the one hand and the individual processing units on the other hand.
• the invention also concerns a display device for realising the above-mentioned method, characterised in that it consists at least of a general processing unit; a display consisting of several display units; an individual processing unit per display unit; means which transmit at least data concerning the image to be displayed transmitted from the general processing unit to the individual processing units in the form of a data stream; means providing for a control communication between the general processing unit and each of the individual processing units in the form of control signals,- and, per individual processing unit, means which collect data from the data stream as a function of the transmitted control signals for further processing and display.
• figure 1 schematically represents a display device according to the invention
• figure 2 represents a model of the display device in figure 1 in perspective
• figure 3 represents the part which is indicated by F3 in figure 2 to a larger scale
• figure 4 represents the back side of the module from figure 2 in perspective
• figure 5 represents the display device in the form of a block diagram
• figure 6 represents a number of histograms with reference to images to be displayed
• figure 7 schematically represents a special image geometry.
• the display device 1 mainly consists of a general processing unit 2 and a display 3 consisting of a screen which is composed of several display units 4, whereby every display unit 4 is equipped with an individual processing unit 5.
• the general processing unit 2 also called digitizer or video engine, consists of an appliance which transforms image signals, either coming from an external source or from an internal source, such as a built-in video player, into digitised signals which are suitable for the reproduction of the image on the display 3.
• the display units 4 consist of tile-shaped modules which, as represented in figure 1, can be assembled by attaching them on an appropriate supporting structure, for example a frame 6.
• the modules are preferably fastened in the frame 6 in a detachable manner, for example by making use of fastening elements 7, as represented in figure 4, with which the modules can be snapped in the frame 6.
• the image side 8 of the display units 4 is equipped with luminous elements, in particular LED's (Light Emitting Diodes) , which are indicated hereafter in a general manner with the reference 9, but which are indicated with the references 9A to 9E when represented in detail .
• LED's Light Emitting Diodes
• the LED's 9A and 9E are red for example, whereas the LED's 9B and 9D are green and the LED's 9C are blue.
• Every set of LED's 9 hereby forms a pixel of the images to be formed. It should be noted that such a pixel can be composed in different ways, of three colours or of a combination of different groups of LED's 9.
• the LED's 9A-9B-9C form a group of basic colours with which all colours can be formed. The same goes for the LED's 9B-9C-9E as well as for 9D-9C-9E and 9A-9C-9D.
• the invention is special in that the display device 1, as is schematically represented in figure 5, is equipped with means 10 which at least transmit data concerning the image to be displayed transmitted from the general processing unit 2 to the individual processing units 5 in the form of a data stream 11; means 12 providing for a control communication between the general processing unit 2 and each of the individual processing units 5 in the form of control signals 13; and, per individual processing unit 5, means 14 which collect data from the data stream 11 as a function of the transmitted control signals 13 for further processing and display on the image surface, in this case the LED panel, of the display unit 4 concerned.
• the data stream 11 and the control signals 13 are only represented schematically in the diagram of figure 5 and that, in reality, the data stream 11 and the control signals 13 are not necessarily carried via two different data lines.
• the data stream 11 and the control signals 13 may consist of a single pulse train in which certain intervals are reserved for the data stream 11 and other intervals are reserved for the control signals 13.
• a distributed signal processing is provided for between the general processing unit 2 on the one hand and the individual processing units 5 on the other hand. This implies that a number of data are processed and calculated in the general processing unit 2, whereas a number of other data are processed and calculated in each of the individual processing units 5.
• This distributed signal processing can be carried out at different levels.
• a distributed signal processing of the signals related to the colour rendering is provided for, in other words a distributed colour processing.
• a distributed signal processing related to the brightness and/or contrast can hereby be provided for.
• image stabilisation and/or noise suppression - tracking of the illumination of the image, in other words "luminance tracking 1 , whereby certain values of the luminance are included; histogram equalisation as a function of the entire image to be displayed; observing of what is called cue flash and acting appropriately in case of such a cue flash; - reduction of the image in relation to the original input image in the horizontal and/or vertical direction.
• Luminance tracking implies determining for example a fixed relation between the different colours beneath a certain luminance before the signals concerned are transmitted to the individual processing units 5.
• histogram equalisation is meant that a histogram of the entire image content is made and that an evaluation is subsequently made and, if necessary, corrections will be made as a function thereof before the data stream 11 is transmitted to the processing units 5.
• figure 6 represents different curves which can be found in a histogram.
• H hereby represents the luminance value and I the number of times such values occur in this image.
• the curves represent all the pixels of the image.
• the adjustments resulting from the evaluation of the histogram can also be linked to time. This implies that also alterations in the histogram for each of the successive images are detected and taken into account . In case of slow alterations, alterations in the output signal will be made less quickly, as a result of which is obtained a stabilisation effect.
• cue flash is a sudden alteration of the entire image content, in other words a sudden change in the displayed image. It is clear that, at such a moment, the alteration should not be ignored. A detection of the cue flash allows for appropriate action at that moment.
• one or several individual adjustments are made at the individual processing units 5 as well. In particular, these adjustments concern one or several of the following possibilities :
• colour co-ordinates are meant the co-ordinates in the chromaticity diagram. These co-ordinates determine what colour is visually observed, and they depend on several factors. Thus, for example they are linked to the age of the display unit 4, such that the adjustment must be made individually. However, the adjustment contributes to the general smoothness and uniformity of the colour reproduction in the image .
• a dynamic sample weight distribution is applied above, whereby the individual processing units 5 are informed via the control signals 13 of what curve should be followed during the transformation of the linear course into the non-linear course, depending on the aimed effect .
• This technique allows for a refined contrast rendering without requiring a large number of contrast level differences in the signal of the general processing unit 2 towards the individual processing units 5.
• the temperature correction offers the advantage that mutual deviations resulting from temperature differences, irrespective of the cause of these temperature differences, are excluded. Said temperature differences may occur for example when, for a longer length of time, only a part of the display 3 is driven so as to form an image, whereas from a certain moment on, the entire display 3 is used. Consequently, the display units 4 which have not been in use until then will not function at operating temperature, and an adjustment because of the temperature differences is advisable .
• a distributed signal processing of the signals related to the image display in other words a distributed image processing, is provided for.
• An example of such distributed image processing consists in that a distributed signal processing is provided for which makes sure that, both at the general processing unit 2 and at the individual processing units 5, measures are taken to minimise image flickering.
• the line frequency is raised to this end in the general processing unit 2 in order to eliminate what is called the interline flicker. It will be raised for example from 15 kHz to 32 kHz.
• the individual processing units 5 one or several individual adjustments are made which make sure that every display unit 4 operates frequency-independent vertically and horizontally. This adjustment consists for example in realising an automatic pulse width adjustment and/or in carrying out a frequency raise to eliminate what is called surface flicker.
• the pulse width adjustment offers the advantage that one can for example automatically switch from a 50 Hz system to a 60 Hz system without any discontinuities being perceived in the displayed image.
• the automatic pulse width adjustment is preferably carried out by creating free spaces in between the pulses, whose interval is adjusted such that the entire signal becomes totally continuous.
• the frequency is raised from for example 50/60 Hz to at least 100 Hz and better still to 400 Hz.
• a distributed signal processing of the signals determining the image geometry is provided for.
• control signals 13 are hereby transmitted to the individual processing units 5 which indicate which part of the image should be displayed at the display unit 4 concerned, whereby the individual processing units 5 then collect data from the data stream 11, process them and display them, as a function of said control signals 13.
• FIG. 7 An example thereof is represented in figure 7, whereby the entire image which is normally displayed in the rectangle defined by the entire surface of the display 3, is compressed into a triangle 18.
• the image Bl of the picture line 19 must hereby no longer be displayed over the distance X, but over the short distance Y.
• the display units 4A and 4B will not be ordered to collect data from the data stream 11 via the communication protocol which is contained in the control signals 13, whereas the display unit 4C will be ordered to collect all the image information of the image Bl from the data stream 11, and to display this image Bl, of the picture line 19, over the distance Y.
• the general processing unit 2 hereby only gives a command, whereas the recalculation for the display of the image Bl over the distance Y is carried out in the processing unit 5 of the display unit 4C.
• a dynamic image stabilisation is provided for.
• a time-dependant image stabilisation whereby it is verified for pixels of the image how alterations in time occur between successive images, and whereby an image stabilisation effect is provided for before the images are displayed, for example by ignoring or attenuating brief alterations
• a frequency-dependant image stabilisation whereby it is verified how alterations occur in pixels of the image situated next to one another, and whereby an image stabilisation effect is provided for before the images are displayed
• an amplitude-dependant image stabilisation - an image stabilisation as a function of the entire image content .
• Such an image stabilisation can be realised either exclusively at the general processing unit 2 or exclusively at the individual processing units 5, but also distributed over both.
• the improvement of the image display by means of such a dynamic image stabilisation can also be applied in other display units 1 than those described above, namely also in display units which are not assembled from different display units 4 and which do not necessarily have to be of the LED type.
• the dynamic image stabilisation is concerned, the invention is not restricted to the above-described display device 1, and it also extends to other display devices, including CRT projectors, picture tubes, etc.
• both the signals of the data stream 11 and the control signals 13 are successively displayed from one display unit 4 to the next, and a number of, preferably each of the individual processing units 5 is provided with a master clock correction. This implies that all the signals, at each transition to a subsequent display unit 4, are again optimally adjusted to one another, so that possible transmission errors are excluded, if not minimised.
• RGB signals red/green/blue
• master clock correction in particular a cumulation of shifts and errors resulting from what is called jitter is counteracted at the master clock.
• Such a master clock correction is preferably carried out by means of a proprietary crystal clock in each of the individual processing units 5.
• the LED's 9 are driven by means of an uninterrupted current during normal operation, whereby the length of time for which the current is switched on is used as a control parameter. Moreover, in order to adjust the brightness and contrast, the value of the above-mentioned current can be altered.
• the display device 1 preferably also contains means to automatically recognise the position of a display unit 4 in the total image surface. These means consist for example in that, when the processing unit 2 is switched on, it assigns the address "1' to the first display unit 4 coupled in series, the address "2' to the second one, and so on. In case of a systematic "through' coupling as represented in figure 1, and when the number of display units 4 are put in per row, as well as the number of rows of display units 4 among themselves, the processing unit 2 will automatically determine the position of each display unit 4 in the total display 3.

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• Engineering & Computer Science (AREA)
• Theoretical Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Human Computer Interaction (AREA)
• Multimedia (AREA)
• General Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Control Of El Displays (AREA)
• Controls And Circuits For Display Device (AREA)
• Digital Computer Display Output (AREA)
• Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)
• Transforming Electric Information Into Light Information (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (8)

Cited By (14)

Families Citing this family (59)

Family Cites Families (21)

• 1999
  • 1999-04-28 BE BE9900306A patent/BE1012634A3/nl not_active IP Right Cessation
• 2000
  • 2000-04-19 JP JP2000614111A patent/JP2002543457A/ja active Pending
  • 2000-04-19 EP EP00920290A patent/EP1238328B8/en not_active Expired - Lifetime
  • 2000-04-19 EP EP03077322A patent/EP1381020A3/en not_active Withdrawn
  • 2000-04-19 WO PCT/BE2000/000039 patent/WO2000065432A2/en not_active Ceased
  • 2000-04-19 US US09/926,408 patent/US7071894B1/en not_active Expired - Lifetime
  • 2000-04-19 AT AT00920290T patent/ATE363683T1/de not_active IP Right Cessation
  • 2000-04-19 DE DE60035063T patent/DE60035063T2/de not_active Expired - Lifetime
  • 2000-04-19 ES ES00920290T patent/ES2287008T3/es not_active Expired - Lifetime

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