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
  • 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
  • G09F9/33—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 being semiconductor devices, e.g. diodes
• • 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
  • G09F9/35—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 being liquid crystals
• • 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
  • G09G3/34—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 by control of light from an independent source
  • G09G3/3406—Control of illumination source
  • G09G3/342—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
  • G09G3/3426—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines the different display panel areas being distributed in two dimensions, e.g. matrix
• • 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
  • G09G2320/0626—Adjustment of display parameters for control of overall brightness
  • G09G2320/0646—Modulation of illumination source brightness and image signal correlated to each other
• • 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
  • G09G3/34—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 by control of light from an independent source
  • G09G3/3406—Control of illumination source
• • 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
  • G09G3/34—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 by control of light from an independent source
  • G09G3/36—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 by control of light from an independent source using liquid crystals
  • G09G3/3611—Control of matrices with row and column drivers

Definitions

• This invention pertains to systems and methods for displaying images on displays of the type that have two modulators.
• a first modulator produces a light pattern and a second modulator modulates the light pattern produced by the first modulator to yield an image.
• the two layers have different spatial resolutions (e.g. the light source layer's resolution may be about 0.1 % that of the display layer) then both software correction methods and psychological effects (such as veiling luminance) prevent the viewer from noticing the resolution mismatch.
• the two layers have different spatial resolutions (e.g. the light source layer's resolution may be about 0.1 % that of the display layer) then both software correction methods and psychological effects (such as veiling luminance) prevent the viewer from noticing the resolution mismatch.
• LCD computer displays and televisions are commercially available.
• Such displays and televisions include circuitry for controlling the amount of light transmitted by individual pixels in an LCD panel.
• the task of deriving driving from image data signals to control a light source layer and display layer can be computationally expensive. Deriving such signals can be executed by a processor of a computer's video/graphics card, or by some other appropriate processor integral to a computer, to the display itself or to a secondary device.
• the task of deriving from image data signals to control a light source layer and display layer can be computationally expensive. Deriving such signals can be executed by a processor of a computer's video/graphics card, or by some other appropriate processor integral to a computer, to the display itself or to a secondary device. Performance limitations of the processor can undesirably limit the rate at which successive image frames can be displayed. For example, if the processor is not powerful enough to process incoming video data at the frame rate of the video data then an observer may detect small pauses between successive frames of a video image such as a movie. This can distract the observer and negatively affecting the observer's image viewing experience. [0007] There is a need for practical, cost effective and efficient systems for displaying images on displays of the general type described above.
• Figure 1 graphically depicts segmentation of a point spread function (PSF) into narrow and wide base Gaussian segments.
• Figures 2A, 2B and 2C graphically depict the splitting of a
• PSF point spread function
• Figure 4 graphically depicts high and low byte point spread functions corresponding to the point spread function depicted in Figure
• Figure 6 is a schematic diagram of a display.
• Figure 7 is a flowchart illustrating a method for displaying an image on a display having a controllable light source layer and a controllable display layer.
• Figure 8 is a flowchart illustrating a method for determining an effective luminance pattern.
• Figure 9 is a flowchart illustrating a method for determining an effective luminance pattern or a component of an effective luminance pattern. Description
• the invention may be applied in a wide range of applications wherein an image is displayed by producing a light pattern that is determined at least in part by image data, and modulating the light pattern to yield an image.
• the light pattern may be produced by any suitable apparatus. Some examples include: • A plurality of light sources driven by driver circuits that permit brightnesses of the light sources to be varied. • A fixed or variable light source combined with a reflection type or transmission type modulator that modulates light from the light source.
• the following description relates to non-limiting example embodiments in which the light pattern is produced on one side of an LCD panel by an array of light-emitting diodes and the LCD panel is controlled to modulate the light of the light pattern to produce a viewable image.
• the array of LEDs can be considered to constitute a first modulator and the LCD panel constitutes a second modulator.
• rendering image frames or a frame set for display on an LED/LCD layer display entails the following computational steps: 1. Obtaining image data (which may be full screen or partial screen image data). 2. Deriving from the image data appropriate driving values for each LED of the first modulator, using suitable techniques well known to persons skilled in the art (e.g. nearest neighbour interpolation which may be based on factors such as intensity and colour). 3. The derived LED driving values and the point spread functions of LEDs on the LED layer as well as the characteristics of any layers between the LED layer and the LCD layer are used to determine the effective luminance pattern which will result on the LCD layer when the LED driving values are applied to the LED layer.
• the image defined by the image data is then divided by the effective luminance pattern to obtain raw modulation data for the LCD layer.
• the raw modulation data is modified to address issues such as non-linearities or other artifacts arising in either of the LED or LCD layers. These issues can be dealt with using suitable techniques well known to persons skilled in the art (e.g. scaling, gamma correction, value replacement operations, etc.). For example, creating the modified modulation data may involve altering the raw modulation data to match a gamma correction curve or other specific characteristics of the LCD layer.
• Final modulation data for the LCD (which may be the raw modulation data or the modified modulation data) and the driving data for the LEDs are applied to drive the LCD and LED layers to produce the desired image.
• the point spread function of each LED in an LED layer is determined by the geometry of the LED.
• a simple technique for determining an LED layer's total effective luminance pattern is to initially multiply each LED's point spread function (specifically, the point spread function of the light which is emitted by the LED and passes through all optical structures between the LED and LCD layers) by a selected LED driving value and by an appropriate scaling parameter to obtain the LED's effective luminance contribution, for that driving value, to each pixel on the LCD layer.
• the luminance contributions of every LED in the LED layer can be determined and summed to obtain the total effective luminance pattern, on the LCD layer, that will be produced when the selected driving values are applied to the LED layer.
• these multiplication and addition operations are very computationally expensive (i.e. time consuming), because the effective luminance pattern must be determined to the same spatial resolution as the LCD layer in order to facilitate the division operation of step 4 above.
• the computational expense is especially great if the LED point spread function has a very wide "support.”
• the "support” of an LED point spread function is the number of LCD pixels that are illuminated in a non-negligible amount by an LED.
• the support can be specified in terms of a radius, measured in LCD layer pixels, at which 5 000807
• the support corresponds to a number of LCD pixels that are illuminated in a significant amount by each LED.
• each LED has a point spread function having a support of 150 LCD pixels then each pixel in the center portion of the LCD layer will be illuminated by light from approximately 35 of the LEDs.
• Calculation of the effective luminance pattern for this example accordingly requires 35 operations for each pixel of the LCD layer, in order to account for the light contributed to each pixel by each relevant LED. Where the LCD layer has a high spatial resolution, this is very computationally expensive (i.e. time consuming).
• the scaling may be done using suitable linear, Gaussian or other interpolation techniques. Such spatial resolution reduction yields an approximately linear decrease in the computational cost of establishing the effective luminance pattern.
• Many available interpolation methods that can be used to scale up an effective luminance pattern computed at a lower resolution are computationally inexpensive as compared to the computational cost of computing the effective luminance pattern at the resolution of the LCD or other second light modulator.
• Point Spread Function Decomposition The computational cost of image rendering can also be reduced by decomposing the point spread function of each light source (e.g. each LED) into several components (e.g. by performing a Gaussian decomposition) in such a way that the recombination of all of the components yields the original point spread function. An effective luminance pattern can then be determined separately for each component. Once an effective luminance pattern has been determined for each component, those effective luminance patterns can be combined to produce a total effective luminance pattern. The combination may be made by summing, for example. [0030] Computing the effective luminance patterns contributed by the components may be performed at the resolution of the LCD layer or at a reduced resolution, as described above.
• Figure 1 depicts (solid line) an example LED point spread function having a steep central portion 10 and a wide tail portion 12.
• the actual point spread function can be decomposed into a narrow base Gaussian component 14A and a wide base Gaussian component 14B, as depicted.
• the wide base Gaussian component 14B (dotted line) contributes relatively little image intensity, in comparison to narrow base Gaussian segment 14A (dashed line). Further, wide base Gaussian component 14B is more slowly varying than narrow base Gaussian component 14A. Accordingly, an effective luminance pattern for narrow base Gaussian component 14A may be determined at a moderately high spatial resolution while an effective luminance pattern for the wide base Gaussian component 14B can be computed at a significantly lower spatial resolution. This preserves a substantial portion of the image intensity information contained in narrow base Gaussian component 14A and is still relatively fast since the effective support of the narrow base Gaussian segment is small and thus few LCD pixels are covered by that component. By contrast, since wide base Gaussian component 14B contains relatively little image intensity information, that component can be processed relatively quickly at low resolution without substantially degrading the resolution of the total effective luminance pattern produced by combining the patterns derived for each component.
• the 8-bit values are preferably extracted only after all necessary scaling and manipulation operations have been applied to the input 16-bit data.
• Figure 2 A depicts a 16-bit point spread function;
• Figures 2B and 2C respectively depict the 8-bit high and low byte components of the Figure 2A 16-bit point spread function.
• the low byte component can be separated into two regions.
• a central region lying within the boundary on which the point spread function characterized by the high byte component reaches zero.
• the low-byte component typically varies in an irregular saw-tooth pattern (as depicted in Figure 3) if the original 16-bit point spread function is reasonably smooth. This is because, in the central region, the portion of the point spread function characterized by the low byte component augments the portion of the point spread function characterized by the high byte component.
• the contributions from the low-byte component of the point spread function can be processed differently in these two regions (i.e. the regions inside and outside the radius R) to avoid unwanted artifacts.
• the effective luminance pattern for that region is preferably determined using the same relatively high resolution used to determine the effective luminance pattern for the high byte component's contribution to the point spread function, as previously described.
• the effective luminance pattern for the region outside the radius R can be determined using a much lower resolution, without substantial loss of image intensity information.
• the results are individually up-sampled to match the resolution of the LCD layer, then recombined with appropriate scaling factors being applied.
• Recombination typically involves summation of the values for the two low byte component regions and the value for the high byte component, after the value for the high byte component has been multiplied by 256.
• Figure 5 depicts the result obtained by using an iteratively-derived interpolation technique to reduce the resolution of the effective luminance pattern to match the resolution of the LED layer.
• the pixel values at the LED layer's resolution are not the LED driving values— they are the luminance values of the effective luminance pattern before interpolation.
• the interpolation function can be determined using standard iteration methods and a random starting condition. As seen in Figure 5, convolution of the iteratively-derived interpolation function with the effective luminance pattern values yields results which are reasonably close to the actual effective luminance pattern.
• Figures 6 to show some example embodiments of the invention.
• Figure 6 shows a display 30 comprising a modulated light source layer 32 and a display layer 34.
• Light source layer 32 may comprise, for example: • an array of controllable light sources such as LEDs;
• a controller 40 comprising a data processor 42 and suitable interface electronics 44A for controlling light source layer 32 and 44B for controlling display layer 34 receives image data 46 specifying images to be displayed on display 30.
• Each of blocks 72 may comprise, for each light source of light source layer 32, multiplying values that define a component of the point spread function by a value representing the intensity of the light source.
• the effective luminance patters determined in blocks 72 are combined, for example by summing, to yield an overall estimate of the effective luminance pattern that would be produced by applying the first driving signals to light source layer 32.
• Method 80 begins in block 82 with data characterizing a point spread function (or a PSF component) for a light source of light source layer 32 and data indicative of how intensely the light source will operate under the control of the first driving signals. Method 80 combines these values (e.g. by multiplying them together) to obtain a set of values characterizing the contribution of the light source to the effective luminance pattern at various spatial locations. [0061] Block 84 obtains high-order and low-order components of the resulting values. In some embodiments, the resulting values are 16- bit words, the high-order component is an 8-bit byte and the low-order component is an 8-bit byte.
• Contributions to the ELP are determined separately for the high-order and low-order components in blocks 86 and 88.
• the area of support for which values are included in the high-order contribution of 86 is typically significantly smaller than the area of support for which values are included in the low-order contribution of block 88.
• Block 88 typically computes the low-order contribution for points located within the area of support of the high-order contribution (block 90) separately than for points located outside of the area of support of the high-order contribution (block 92).
• Blocks 86, 90 and 92 may be performed in any order or simultaneously.
• blocks 86, 90 and 92 are combined to yield an overall ELP.
• the computations in blocks 86 90 and 92 may be performed primarily or entirely in the 8-bit domain (i.e. using 8-bit operations on 8-bit operands) in the case that the high-order and low-order components are 8-bit bytes or smaller.
• the program product may comprise, for example, physical media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, or the like or transmission-type media such as digital or analog communication links.
• the computer-readable signals on the program product may optionally be compressed or encrypted.
• a component e.g. a member, part, assembly, device, processor, controller, collimator, circuit, etc.
• reference to that component should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.
• the light source layer may comprise a number of different types of light source that have point spread functions different from one another;
• the display may comprise a colour display and the computations described above may be performed separately for each of a number of colours.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Computer Hardware Design (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Liquid Crystal Display Device Control (AREA)
• Liquid Crystal (AREA)
• Television Systems (AREA)
• Controls And Circuits For Display Device (AREA)

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• 2005
  • 2005-05-27 KR KR1020077001836A patent/KR101121131B1/en not_active Expired - Lifetime
  • 2005-05-27 EP EP05748546.8A patent/EP1779362B1/en not_active Expired - Lifetime
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  • 2005-05-27 WO PCT/CA2005/000807 patent/WO2006010244A1/en not_active Ceased
  • 2005-05-27 ES ES05748546.8T patent/ES2575929T3/en not_active Expired - Lifetime
  • 2005-05-27 DK DK05748546.8T patent/DK1779362T3/en active
  • 2005-05-27 CA CA3043550A patent/CA3043550C/en not_active Expired - Lifetime
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• 2013
  • 2013-09-19 JP JP2013193722A patent/JP5973403B2/en not_active Expired - Lifetime
• 2015
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