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
  • 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
  • G09G2300/023—Display panel composed of stacked panels
• • 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
  • G09G3/2007—Display of intermediate tones
  • G09G3/2014—Display of intermediate tones by modulation of the duration of a single pulse during which the logic level remains constant

Definitions

• the present invention is in the field of electronics and relates to a method and a device making it possible to obtain a parabolic light energy curve of light sources constituted by light emitting diodes (LEDs) diffusing images, in the field of giant screens. , ie screens made up of a very large number of diodes, possibly grouped into "pixels" if it is a question of obtaining an apparent polyclomia.
• LEDs light emitting diodes
• the restitution of the luminance levels, or modulation, of an image by the light sources on a giant screen is essentially carried out by an all or nothing time control of said sources.
• the modulation is said to have a variable conduction duration from said sources.
• This universally used modulation method has a major flaw: it. does not correctly restore the light energy power curve of the luminance levels of the images to be reproduced such that these images are determined by image generators with cyclic ratio, and this defect is reflected on the screen by a blinking of the image in areas of low light.
• the main idea of the invention was to parabolically modulate the duration of the steps of the refresh signal whose pseudo-frequencies, even the highest, corresponding to the shortest steps at the end of the cycle are entirely compatible with their passage. in wired connections. Consequently, a parabolic progression of the luminance levels is reconstituted without having to have them transit in digital form by the wire connections of the image signal.
• a device for displaying light images of the type of device called “giant screens” of the type comprising a plurality of light sources consisting of light-emitting diodes assembled on a panel, a first signal generator called signal " image ", connected by long wire link to a first so-called image signal input of said control module, said generator delivering digital signals representative of the light intensity of a point in the image, a control module of each said diode located in the vicinity of said diode and connected to it by short wire link, said control module delivering, from digital signals received from the image signal generator, a duty cycle control signal having a time base of duration b divisible in steps, and a second generator of refresh signal, of time base of duration (period) equal to b, said seco nd generator being connected by long wired link to a second so-called refresh input, of said control module, is generally characterized in that the generator, said second, of refresh signal is a period time base signal generator equal to b divided into a number of steps
• the so-called second refresh signal generator is a basic signal generator with a time period equal to b divided into a predetermined number of steps preferably equal to 256, whose duration of the so-called first step at the end of the cycle is equal to b / 256 2 .
• the duration of the successive steps of a refresh signal varies according to a quadratic or parabolic progression.
• the n leme does not have a duration equal to (b / 256 2 ) xn 2
• the time base b having a duration of 10 mS
• the first step has a duration of (10/256 2 ) xl 2 mS, i.e. 0.00015 mS
• the second step has a duration of (10 / 256 2 ) x2 2 mS, or 0.00061 mS
• the third step has a duration of (10/256 2 ) x3 2 mS, or 0.00137 mS surgeetc .
• the second generator is a is a voltage controlled variable oscillator (NCO).
• NCO voltage controlled variable oscillator
• the second generator could be a programmed memory whose written write bits are in parabolic progression acting as an oscillator for reading.
• giant screen namely: process consisting in multiplexing at the level of the control member 4 of the LEDs, the image signal coming from a generator with a quadratic (or parabolic) signal from the cycle refresh clock of said control member, or also know: by parabolically modulating the clock signal.
• the invention relates to the screen itself as soon as it incorporates such a control device or the means implementing the method.
• a giant screen 1 is generally divided into a plurality of modular elements such as 2 each comprising a multitude of light sources 3 (LED), each light source 3 being connected by a short wire link 4 to a module 5 control (PWM) of time data which receives on the one hand by a wired link 6 the image data of the image generator 7, and on the other hand by wired link 8 a refresh cycle frequency originating from a generator 9 clock signal.
• LED light sources 3
• PWM module 5 control
• the frequency of the image signals (14) coming from the image generator is between approximately 10 and 30 megahertz.
• the refresh cycle frequency of the clock signal generator 9 is fixed, that is to say that it is stable over time; such a clock signal is shown at 10, the time base of which (10 mS) is divided into constant steps, each step corresponding to an illumination or non-illumination time of the diode 3, and correspondingly in 12 the diode control signal at the output of module 5 (or at the input of LED 3).
• the control signal will not include an illumination or extinction duration of less than 10/256 mS, ie 0.039 mS.
• the signal 13 coming from the module, or at the input of the LED 3, when it is controlled by a time base with step with parabolic variation 11, can present signals of as short duration that 10/256 2 is 0.00015 mS.
• This last signal duration, observed at the output of the PWM module, or at the input of the diode, or even by time photometric analysis of the illumination of the diode, is characteristic of the invention. 5 Or, typically, we will find on the screen, in the vicinity of the LEDs; or any other all-or-nothing luminescence device, on the one hand, points or terminals which will be the seat of a frequency signal of the order of 10 MHz to
• 30 MHz which may be the image signal 14, and on the other hand points, or terminals which will be the seat of a signal of the parabolic progression type, with a pseudo-frequency of the order of 6 MHz, which is reflected, on visual examination of the screen, by an image substantially identical to the source image.
• the invention is not limited to the parabolic correction of the luminance but that it can extend to the correction of any other defects linked to the structure or the components of the panels, or even to the programmed modification of illuminating images

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Transforming Electric Information Into Light Information (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=8861098

Family Applications (1)

Country Status (3)

Family Cites Families (4)

• 2001
  • 2001-03-01 FR FR0103444A patent/FR2821694B1/fr not_active Expired - Fee Related
• 2002
  • 2002-03-01 WO PCT/FR2002/000738 patent/WO2002071381A1/fr not_active Ceased
  • 2002-03-01 EP EP02708433A patent/EP1366487A1/de not_active Withdrawn

Non-Patent Citations (1)

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