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
  • G09G3/28—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 luminous gas-discharge panels, e.g. plasma panels
  • G09G3/288—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 luminous gas-discharge panels, e.g. plasma panels using AC panels
  • G09G3/296—Driving circuits for producing the waveforms applied to the driving electrodes
• • 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
  • G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
  • G09G3/2022—Display of intermediate tones by time modulation using two or more time intervals using sub-frames
• • 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
  • G09G2320/02—Improving the quality of display appearance
  • G09G2320/0261—Improving the quality of display appearance in the context of movement of objects on the screen or movement of the observer relative to 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
  • G09G2320/0266—Reduction of sub-frame artefacts
• • 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
  • G09G2320/10—Special adaptations of display systems for operation with variable images
  • G09G2320/106—Determination of movement vectors or equivalent parameters within the image
• • 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
  • G09G3/28—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 luminous gas-discharge panels, e.g. plasma panels
  • G09G3/2803—Display of gradations

Definitions

• the invention relates to driving a display such as a plasma display panel.
• An (AC) plasma display panel (PDP) and a digital (micro-)mirror device (DMD) are bi-level displays with a memory function, i.e. pixels (picture elements) can only be turned on or off.
• a memory function i.e. pixels (picture elements) can only be turned on or off.
• three phases can be distinguished; an erase sequence, an addressing sequence and a sustain sequence.
• the first sequence the memories of all pixels are cleared.
• the second addressing phase is necessary.
• the pixels are addressed on a line at a time basis.
• the pixels that should turn on are conditioned in such a way, that they turn on when a voltage is put across its electrodes. The conditioning is done for all pixels in a display that should be switched on.
• a third phase the sustain phase, is required in which the luminance is generated. All pixels that were addressed, turn on as long as the sustain phase lasts.
• the sustain period is common for all pixels of a display, thus, during this sustain period, all pixels on the screen that were addressed are switched on simultaneously.
• the field period is divided into several sub-fields each consisting of a sequence of erase, address and sustain.
• the grey-scale contribution of each sub-field is determined by varying the duration of the sustain phase, i.e. how long the pixels are switched on.
• the duration of the sustain phase is further denoted as the weight of a sub-field.
• the higher the weight of a sub-field the higher the luminance of a pixel that is switched on during the sustain phase.
• the grey-scale itself is now generated in such a way that the luminance value is divided into several sub-fields in which the sub-fields have various weights, i.e. the duration of the sustain phase is proportional to a weight factor, thus also the luminance output is proportional to the same weight factor.
• the sub-fields can be started in two fashions; they can be equally divided over a field period, or they can start when the previous one is finished. The latter situation is shown in Fig. 1.
• a field period including six sub-fields SF1-SF6 is shown for a conventional PDP.
• Each sub-field SFi includes an erase period EP, an addressing period AP, and a sustain period SP.
• the length of the sustain period SP of a sub-field determines its impact on the output luminance.
• Figs. 2A-2D show the artifacts resulting from motion at a speed of 2 pixels per field period.
• Fig. 2D shows a Time vs. Position diagram in which the six sub-fields together forming a first field T 0 are shown on the vertical axis, and position P is shown on the horizontal axis.
• Increasing luminance values L are set out horizontally; these luminance values are built up in a digital manner by means of the various sub-fields having binary weights.
• Fig. 2C shows where the various sub-field informations are perceived as a result of the motion at 2 pixels per field period.
• Fig. 2 A shows the resulting luminance on the retina, as well as a line R indicating the intended ramp. The difference between the intended ramp and the actually perceived luminance on the retina is a problem to be solved. It can be seen from Fig. 2A that the observed luminance can differ a lot from the actual still image data. This method calculates the precise position of the sub-fields and weights of the pixels under the assumption that the eye is tracking the motion according to the motion vectors.
• FIG. 2D shows a part of the black and white luminance ramp.
• the motion vectors are drawn with a speed of 2 pixels per field period.
• the projections of the separate sub-fields are drawn on a diagram in which the luminance is drawn as function of the position on the retina when the eye is perfectly tracking the motion with a speed of 2 pixels per field period. All luminances generated by the sub-fields that are received at the same positions on the retina are integrated resulting in a diagram in which the total luminance received by the retina has been drawn as a function of the position on the retina (this is shown in Fig. 2A). What can be seen is that the pattern on the retina still does not resemble the still image luminance ramp. There is still a bright vertical bar visible.
• a luminance of 20 must be shown as projected on the motion vector.
• the right luminance level of the vertical line is obtained, when this pattern has a speed of 6 pixels per field period to the right.
• the luminances that are required are the luminance levels shown on the motion vectors, i.e. the luminances of the pixels that are shown are the luminances of the compensation pattern.
• OL indicates the obtained luminance when tracking, as a result of putting not the desired ramp itself, but the compensation pattern CP on the display.
• the luminances of the pixels that are visible are the luminances projected on the motion vectors when the eyes are tracking the motion of 6 pixels per field period.
• a first aspect of the invention provides a method as defined in claim 1. Further aspects of the invention provide a display driving device as defined in claim 7 and a display apparatus as defined in claim 8. Advantageous embodiments are defined in the dependent claims.
• field information from a field of an image signal is distributed over a plurality of sub-fields, and a start time for each sub-field is generated in dependence upon motion.
• Fig. 1 illustrates an example of a field period for an AC plasma display
• Figs. 2A-2D illustrate motion artifacts for a luminance ramp at a speed of 2 pixels per field period
• Fig. 3 illustrates motion-compensation of one grey-scale on the plasma screen
• Fig. 4 illustrates a motion-compensated luminance ramp
• Figs. 5A-5D illustrate motion-compensation at a speed of 3 pixels per field period
• Figs. 6A-6D illustrate motion-compensation with an improved sub-field order and timing at a speed of 2 pixels per field period
• Figs. 7A-7D illustrate motion-compensation with an improved sub-field order and timing at a speed of 3 pixels per field period
• Figs. 8A-8D and 9 illustrate motion-compensation with an improved sub-field order and timing at a speed of 4 pixels per field period
• Fig. 10 shows a block circuit diagram of a display apparatus in accordance with the present invention.
• the sub-field order and timing is fixed for a given display panel.
• the motion- compensation circuit could calculate (or a LUT with preprogrammed values could be used) the most optimum sub-field order and timing for a given speed.
• the sub-field timing is hereby determined by the compensation circuit and is not fixed any more.
• a preferred sub- field order and timing belonging to a speed of 4 pixels per field period from Figs. 8A-8D is given in Fig. 9, in which at the right-hand side the sub-field order and timing is given.
• the second problem is a fundamental problem, it hardly never occurs that there is only one speed apart from O in a natural scene. What mostly is the case is that only one speed within a certain small range is present much more often than any other speed.
• motion artifacts mostly occur around the most significant sub-fields (the sub- fields with the highest weights) at spatial sub-field changes when only a small change in grey-scale must be achieved.
• Both properties can be used to calculate the speed that shows most artifacts for that scene when a normal sub-field order would be used. This speed can be used as an input to calculate a more optimum sub-field timing and order. When implementing this in this way, flicker is likely to occur due to a sudden shift of a significant sub-field.
• a method is presented to reduce the motion artifacts by dynamically adapting the sub-field order and timing dependent on the contents of a video image.
• the most common speed can be found whereby artifacts are likely to occur.
• the best sub-field order and timing is calculated and this is applied in the panel.
• a low- pass filtering this information prevents introduction of flicker due to sudden changes in sub- field timing.
• the speed to which the sub-field order is adjusted can be one of the following alternatives:
• a speed obtained in dependence on one or more of the above speeds by taking e.g. an average or a median.
• the MSB sub-field i.e. the sub-field having the highest sub-field weight
• the MSB is put at a position close to the middle of that line to accommodate for motion-estimation errors.
• ⁇ t is the time difference between the generation of the MSB-1 sub-field with reference to the MSB sub-field
• x is the displacement expressed in full pixels, thereby reducing the rounding error to
• Tf is the field time.
• the MSB-1 sub-field is put at an intersection close to that of the MSB sub-field to reduce artifacts resulting from motion estimation errors. If there are several sub-fields having an identical highest weight, one of these sub-fields is taken for the above-mentioned MSB sub-field, while another of these sub- fields is taken for the above-mentioned MSB-1 sub-field, etc.
• Fig. 10 shows a block circuit diagram of a display apparatus in accordance with the present invention.
• An antenna A receives a television signal, which is applied to a tuner T.
• An output signal of the tuner T is applied to a video signal processor VP.
• An output signal of the video processor VP is applied to an analysis unit AU for analyzing speeds in an image and the contents of the image.
• An output signal of the analysis unit AU is applied to sub-field order and timing calculator SOC for calculating the most optimal sub-field order and timing in accordance with the present invention as described above.
• the output signal of the video processor VP is applied to a display driver DD, an output of which is connected to a PDP or DMD display D.
• a control input of the display driver DD is connected to an output of the sub-field order and timing calculator SOC for adjusting the sub-field order in accordance with the present invention.
• the past is taken into account (low-pass filtering).
• Motion-compensation is based on the sub-field order and timing.
• This can have been stored into a LUT (look-up table) ROM.
• Fig. 11 explains the notion positional error by means of a Time versus Position diagram of the type of Fig. 2D and other figures described above.
• the positional error PE mentioned above is the difference between the actual position (always an integer position) of a pixel in a sub-field on the display grid (indicated by a dot) on the one hand, and the line indicating the motion trajectory.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Power Engineering (AREA)
• Plasma & Fusion (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Transforming Electric Information Into Light Information (AREA)
• Liquid Crystal Display Device Control (AREA)
• Control Of Gas Discharge Display Tubes (AREA)

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• 1999
  • 1999-03-04 JP JP54797699A patent/JP2002508090A/ja active Pending
  • 1999-03-04 WO PCT/IB1999/000375 patent/WO1999049448A2/en not_active Ceased
  • 1999-03-04 KR KR1019997010860A patent/KR100623404B1/ko not_active Expired - Fee Related
  • 1999-03-04 EP EP99903882A patent/EP0983584A2/en not_active Withdrawn
  • 1999-03-22 US US09/273,937 patent/US6373477B1/en not_active Expired - Fee Related

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