WO2010067601A1 - プラズマディスプレイ装置の駆動方法 - Google Patents
プラズマディスプレイ装置の駆動方法 Download PDFInfo
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- WO2010067601A1 WO2010067601A1 PCT/JP2009/006739 JP2009006739W WO2010067601A1 WO 2010067601 A1 WO2010067601 A1 WO 2010067601A1 JP 2009006739 W JP2009006739 W JP 2009006739W WO 2010067601 A1 WO2010067601 A1 WO 2010067601A1
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- coding table
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- 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
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/06—Details of flat display driving waveforms
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- 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
- G09G2320/0242—Compensation of deficiencies in the appearance of colours
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- 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
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
- G09G2330/02—Details of power systems and of start or stop of display operation
- G09G2330/021—Power management, e.g. power saving
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
- G09G2330/02—Details of power systems and of start or stop of display operation
- G09G2330/025—Reduction of instantaneous peaks of current
Definitions
- the present invention relates to a driving method of a plasma display device using an AC type plasma display panel.
- a plasma display panel (hereinafter abbreviated as “panel”), which is a typical image display device having a large number of pixels arranged in a plane, has a large number of discharge cells having scan electrodes, sustain electrodes, and data electrodes. .
- the panel performs color display by exciting and emitting phosphors by gas discharge generated inside each discharge cell.
- a subfield method is mainly used as a method for displaying an image.
- one field period is composed of a plurality of subfields whose luminance weights are determined in advance, and an image is displayed by controlling light emission or non-light emission of each discharge cell in each subfield.
- the plasma display device includes a scan electrode drive circuit for driving the scan electrodes, a sustain electrode drive circuit for driving the sustain electrodes, and a data electrode drive circuit for driving the data electrodes.
- a driving circuit for each electrode of the plasma display device applies a necessary driving voltage waveform to each electrode.
- the data electrode driving circuit applies an address pulse for an address operation independently for each of a large number of data electrodes based on the image signal.
- each data electrode is a capacitive load having a stray capacitance between the adjacent data electrode, scan electrode and sustain electrode. Therefore, in order to apply a drive voltage waveform to each data electrode, this capacity must be charged and discharged. As a result, the data electrode driving circuit requires power consumption for that purpose.
- the power consumption of the data electrode drive circuit increases as the charge / discharge current of the capacity of the data electrode increases, but this charge / discharge current largely depends on the image signal to be displayed. For example, when the address pulse is not applied to all the data electrodes, the charge / discharge current is “0”, so that the power consumption is also minimized. Conversely, when the address pulse is applied to all the data electrodes, the charge / discharge current is “0”, so the power consumption is small. However, when an address pulse is randomly applied to the data electrodes, the charge / discharge current increases and the power consumption also increases.
- the power consumption of the data electrode driving circuit is calculated based on the image signal, and when the power consumption is large, the writing operation is performed from the subfield having the smallest luminance weight.
- a method of prohibiting and limiting the power consumption of the data electrode driving circuit has been proposed (see, for example, Patent Document 1).
- a method of reducing the power consumption of the data electrode driving circuit by replacing the original image signal with an image signal that reduces the power consumption of the data electrode driving circuit is disclosed (for example, see Patent Document 2).
- Patent Documents 1 and 2 are mainly used to protect the plasma display device from destruction when the power consumption increases excessively, and there is a possibility that the display quality of the image is greatly impaired.
- one field period is composed of a plurality of subfields whose luminance weights are determined in advance, and a plurality of combinations are selected from arbitrary combinations of the subfields to display combinations.
- a set is created, and gradations are displayed by controlling the light emission or non-light emission of the discharge cells using the combination of subfields belonging to the display combination set.
- the driving method of the plasma display device includes a plurality of display combination sets having different numbers of combinations and a random number generation unit that generates random numbers, and each of the red image signal, the green image signal, and the blue image signal
- a display combination set selected from a plurality of display combination sets based on a predetermined selection criterion is used, and a disturbance based on a random number is added to the predetermined selection criterion.
- the predetermined selection criterion for the red image signal of the present invention may be a ratio between the signal level of the red image signal and the signal level of the green image signal.
- the predetermined selection criterion for the green image signal of the present invention may be a ratio between the signal level of the green image signal and the larger signal level of the red image signal and the blue image signal.
- the predetermined selection criterion for the blue image signal of the present invention may be a ratio between the signal level of the blue image signal and the signal level of the green image signal.
- the predetermined selection criteria for the color image signals of the red image signal, the green image signal, and the blue image signal of the present invention are the absolute value of the spatial difference with respect to the image signal of that color and the image signal of that color. It may be a ratio to the signal level.
- the average value of the Hamming distance between a certain gradation in the display combination set with a small number of combinations and the next highest gradation according to the present invention is a certain gradation in the display combination set with a large number of combinations and the next. It is desirable to be smaller than the average value of the Hamming distance with a very high gradation.
- FIG. 1 is an exploded perspective view showing the structure of the panel of the plasma display device in accordance with the first exemplary embodiment of the present invention.
- FIG. 2 is an electrode array diagram of the plasma display device.
- FIG. 3 is a circuit block diagram of the plasma display device.
- FIG. 4 is a diagram showing a driving voltage waveform of the plasma display device.
- FIG. 5A is a diagram showing a coding table used in the plasma display apparatus.
- FIG. 5B is a diagram showing a coding table used in the plasma display device.
- FIG. 5C is a diagram showing a coding table used in the plasma display device.
- FIG. 5D is a diagram showing a coding table used in the plasma display apparatus.
- FIG. 6 is a diagram schematically showing the proper use of the coding table of the plasma display device.
- FIG. 7 is a schematic diagram showing how the coding table is switched in the plasma display device.
- FIG. 8 is a circuit block diagram showing details of an image signal processing circuit of the plasma display device.
- FIG. 9 is a circuit block diagram of an R comparison unit in the plasma display device.
- FIG. 10A is a diagram showing a coding table used in the plasma display device in accordance with the second exemplary embodiment of the present invention.
- FIG. 10B is a diagram showing a coding table used in the plasma display device in accordance with the second exemplary embodiment of the present invention.
- FIG. 10C is a diagram showing a coding table used in the plasma display device in accordance with the second exemplary embodiment of the present invention.
- FIG. 10A is a diagram showing a coding table used in the plasma display device in accordance with the second exemplary embodiment of the present invention.
- FIG. 10B is a diagram showing a coding table used in the plasma display device in accordance with the second exemplary embodiment of the present invention.
- FIG. 10D is a diagram showing a coding table used in the plasma display device in accordance with the second exemplary embodiment of the present invention.
- FIG. 10E is a diagram showing a coding table used in the plasma display device in accordance with the second exemplary embodiment of the present invention.
- FIG. 10F is a diagram showing a coding table used in the plasma display device in accordance with the second exemplary embodiment of the present invention.
- FIG. 11A is a diagram showing an example of a display image in the plasma display device.
- FIG. 11B is a diagram showing a difference signal of an example of a display image in the plasma display device.
- FIG. 12 is a diagram showing the proper use of the coding table for the image signal of the plasma display device.
- FIG. 11A is a diagram showing an example of a display image in the plasma display device.
- FIG. 11B is a diagram showing a difference signal of an example of a display image in the plasma display device.
- FIG. 12 is a diagram showing the proper use of
- FIG. 13 is a circuit block diagram showing details of an image signal processing circuit of the plasma display device.
- FIG. 14 is a circuit block diagram of an R data conversion unit, a G data conversion unit, and a B data conversion unit of the plasma display device.
- FIG. 15 is a circuit block diagram of the R comparison unit of the plasma display device in accordance with the third exemplary embodiment of the present invention.
- FIG. 16 is a schematic diagram showing how the coding table is switched in the plasma display device.
- FIG. 1 is an exploded perspective view showing the structure of panel 10 of the plasma display device in accordance with the first exemplary embodiment of the present invention.
- a plurality of display electrode pairs 24 each including a scanning electrode 22 and a sustaining electrode 23 are formed on a glass front substrate 21.
- a dielectric layer 25 is formed so as to cover the display electrode pair 24, and a protective layer 26 is formed on the dielectric layer 25.
- a plurality of data electrodes 32 are formed on the back substrate 31, a dielectric layer 33 is formed so as to cover the data electrodes 32, and a grid-like partition wall 34 is formed thereon.
- a phosphor layer 35R that emits red light, a phosphor layer 35G that emits green light, and a phosphor layer 35B that emits blue light are provided on the side surfaces of the partition walls 34 and the dielectric layer 33.
- the front substrate 21 and the rear substrate 31 are arranged to face each other so that the display electrode pair 24 and the data electrode 32 intersect each other with a minute discharge space interposed therebetween, and the outer periphery thereof is sealed with a sealing material such as glass frit.
- a sealing material such as glass frit.
- a mixed gas of neon and xenon is sealed as a discharge gas.
- the discharge space is partitioned into a plurality of sections by partition walls 34, and discharge cells are formed at the intersections between the display electrode pairs 24 and the data electrodes 32. These discharge cells discharge and emit light to display an image.
- the structure of the panel 10 is not limited to the above-described structure, and may be, for example, provided with a stripe-shaped partition wall.
- FIG. 2 is an electrode array diagram of panel 10 of the plasma display device in accordance with the first exemplary embodiment of the present invention.
- the panel 10 includes n scan electrodes SC1 to SCn (scan electrodes 22 in FIG. 1) and n sustain electrodes SU1 to SUn (sustain electrodes 23 in FIG. 1) which are long in the row direction, and are long in the column direction.
- M data electrodes D1 to Dm data electrode 32 in FIG. 1) are arranged.
- M ⁇ n are formed.
- three adjacent discharge cells including a discharge cell provided with the red phosphor layer 35R, a discharge cell provided with the green phosphor layer 35G, and a discharge cell provided with the blue phosphor layer 35B are provided. It corresponds to one pixel when displaying an image. Therefore, m / 3 ⁇ n pixels are formed on the panel 10, and the pixel at the pixel position (x, y) on the display screen is the scan electrode SCy, the sustain electrode SUy, and the three data electrodes D3x-2. , D3x-1, and D3x are constituted by three discharge cells formed at the intersection.
- FIG. 3 is a circuit block diagram of plasma display device 40 in accordance with the first exemplary embodiment of the present invention.
- the plasma display device 40 includes a panel 10, an image signal processing circuit 41, a data electrode drive circuit 42, a scan electrode drive circuit 43, a sustain electrode drive circuit 44, a timing generation circuit 45, and a power supply circuit that supplies necessary power to each circuit block. (Not shown).
- the image signal processing circuit 41 converts the input image signal into an image signal of each color having the number of pixels and the number of gradations that can be displayed on the panel 10, as will be described in detail later.
- the image signal processing circuit 41 further converts light emission and non-light emission for each subfield of the discharge cell into image data of each color corresponding to “1” and “0” of each bit of the digital signal.
- the data electrode driving circuit 42 converts the image data output from the image signal processing circuit 41 into address pulses corresponding to the data electrodes D1 to Dm, and applies them to the data electrodes D1 to Dm.
- the timing generation circuit 45 generates various timing signals for controlling the operation of each circuit block based on the horizontal synchronization signal and the vertical synchronization signal, and supplies them to each circuit block.
- Scan electrode drive circuit 43 and sustain electrode drive circuit 44 create drive voltage waveforms based on the respective timing signals and apply them to scan electrodes SC1 to SCn and sustain electrodes SU1 to SUn.
- one field is divided into 10 subfields (SF1, SF2,..., SF10), and each subfield is (1, 2, 3, 6, 11, 18, 30, 44). , 60, 81).
- the luminance weight is set to be larger as the luminance weight of the subfield arranged later.
- the number of subfields and the luminance weight of each subfield are not limited to the above values.
- FIG. 4 is a diagram showing a driving voltage waveform of the plasma display device 40 according to the first embodiment of the present invention.
- the data electrodes D1 to Dm and the sustain electrodes SU1 to SUn are held at the voltage 0 (V) and discharged from the voltage Vi1 which is lower than the discharge start voltage with respect to the scan electrodes SC1 to SCn.
- a ramp waveform voltage that gradually increases toward the voltage Vi2 exceeding the start voltage is applied.
- a weak initializing discharge occurs in all the discharge cells, and wall voltages are accumulated on scan electrodes SC1 to SCn, sustain electrodes SU1 to SUn, and data electrodes D1 to Dm.
- the wall voltage on the electrode refers to a voltage generated by wall charges accumulated on the dielectric layer covering the electrode, the phosphor layer, or the like.
- sustain electrodes SU1 to SUn are maintained at positive voltage Ve1, and a ramp waveform voltage that gradually decreases from voltage Vi3 to voltage Vi4 is applied to scan electrodes SC1 to SCn. Then, a weak initializing discharge is caused again in all the discharge cells, and the wall voltages on scan electrodes SC1 to SCn, sustain electrodes SU1 to SUn, and data electrodes D1 to Dm are adjusted to values suitable for the address operation.
- the first half of the initializing period may be omitted.
- the discharge cells that have been subjected to the sustain discharge in the immediately preceding subfield may be omitted.
- An initialization operation is selectively performed.
- FIG. 4 shows drive voltage waveforms for performing the initialization operation having the first half and the latter half in the initialization period of SF1, and performing the initialization operation having only the second half in the initialization period of the subfield after SF2.
- sustain electrodes SU1 to SUn are kept at voltage Ve2, and voltage Vc is applied to scan electrodes SC1 to SCn.
- a scan pulse of voltage Va is applied to the scan electrode SC1.
- an address discharge occurs between data electrode Dk and scan electrode SC1, and between sustain electrode SU1 and scan electrode SC1, and a positive wall voltage is generated on scan electrode SC1 and a negative voltage is applied on sustain electrode SU1. Wall voltage is accumulated.
- the address operation is performed in which the address discharge is caused in the discharge cells to emit light in the first row and the wall voltage is accumulated on each electrode.
- no address discharge occurs at the intersection between the data electrode Dh (h ⁇ k) to which the address pulse is not applied and the scan electrode SC1.
- the above address operation is sequentially performed until the discharge cell in the nth row, and the address period ends.
- the data electrode drive circuit 42 drives each of the data electrodes D1 to Dm.
- each data electrode Dj is a capacitive load. Therefore, in the address period, each time the voltage applied to each data electrode Dj is switched from the voltage 0 (V) to the voltage Vd or from the voltage Vd to the voltage 0 (V), this capacity must be charged and discharged. If the number of times of charging / discharging is large, the power consumption of the data electrode driving circuit 42 also increases.
- sustain electrodes SU1 to SUn are returned to voltage 0 (V), and a sustain pulse of voltage Vs is applied to scan electrodes SC1 to SCn.
- the voltage between scan electrode SCi and sustain electrode SUi is the voltage Vs plus the magnitude of the wall voltage on scan electrode SCi and sustain electrode SUi.
- the discharge start voltage is exceeded.
- a sustain discharge occurs between scan electrode SCi and sustain electrode SUi, and light is emitted. At this time, a negative wall voltage is accumulated on scan electrode SCi, and a positive wall voltage is accumulated on sustain electrode SUi.
- scan electrodes SC1 to SCn are returned to voltage 0 (V), and a sustain pulse of voltage Vs is applied to sustain electrodes SU1 to SUn.
- V voltage 0
- a sustain pulse of voltage Vs is applied to sustain electrodes SU1 to SUn.
- a sustain discharge occurs again between sustain electrode SUi and scan electrode SCi, and the sustain cell is maintained.
- Negative wall voltage is accumulated on electrode SUi, and positive wall voltage is accumulated on scan electrode SCi.
- the sustain discharge continues in the discharge cells that have caused the address discharge in the address period. Done. Note that a sustain discharge does not occur in a discharge cell in which no address discharge has occurred in the address period, and the wall voltage at the end of the initialization period is maintained. Thus, the maintenance operation in the maintenance period is completed.
- SF2 to SF10 perform the same operation as SF1 except for the number of sustain pulses.
- one field period is composed of a plurality of sub-fields with predetermined luminance weights.
- a combination set for display is created by selecting a plurality of combinations from arbitrary combinations of subfields, and the light emission or non-light emission of the discharge cells is controlled by using the combination of subfields belonging to the combination set for display. Key is displayed.
- a display combination set created by selecting a combination of a plurality of subfields is called a “coding table”.
- an image signal of each color that is, a red image signal sigR (hereinafter sometimes simply referred to as “sigR”) and a green image signal sigG (hereinafter simply referred to as “sigG”) may be used.
- sigR red image signal
- sigG green image signal
- sigB blue image signal
- the gradation when displaying black is “0” and the luminance weight “ The gradation corresponding to “N” is expressed as “N”. Therefore, the gradation of the discharge cell that emits light only with SF1 having the luminance weight “1” is “1”, and the discharge cell that emits light with both SF1 with the luminance weight “1” and SF2 with the luminance weight “2”. The gradation is “3”.
- each coding table used for each color image signal is selected from two coding tables and used.
- FIGS. 5A, 5B, 5C, and 5D are diagrams showing a coding table used in plasma display device 40 in the first exemplary embodiment of the present invention.
- FIGS. 5A, 5B, and 5C are 90th combinations of subfields.
- FIG. 5D is a diagram illustrating a first coding table
- FIG. 5D is a diagram illustrating a second coding table having 11 subfield combinations.
- each coding table used for each color image signal is selected from one of the two coding tables based on the signal level of each color image signal.
- the numerical values shown in the leftmost column indicate display gradation values used for display, and the right side shows discharge cells in each subfield when the gradation is displayed. Whether or not to emit light is indicated, “0” indicates non-light emission, and “1” indicates light emission.
- the discharge cell in order to display the gradation “2”, the discharge cell only needs to emit light at SF2, and in order to display the gradation “14”, the discharge cell is displayed at SF1, SF2, and SF5. What is necessary is just to make it light-emit.
- the image signal processing circuit 41 uses the image signals of each color (red image signal sigR, green image signal sigG, blue image signal sigB) as digital signals for light emission and non-light emission for each subfield of the discharge cell.
- image data dataR, green image data dataG, and blue image data dataB are converted into image data of each color (red image data dataR, green image data dataG, and blue image data dataB) corresponding to “1” and “0” of each bit. Therefore, the image data “0000000” displaying the gradation “0” is non-emission with SF1 to SF10, and the image data “1000000000” displaying the gradation “1” is emitted only with SF1, and the gradation “2”.
- the image data “0100000000000” for displaying “1” emits light only with SF2
- the image data “1100000000” for displaying gradation “3” emits light with SF1 and SF2.
- the Hamming distance the number of unequal bits when the corresponding bits of two image data are compared.
- the image data of gradation “0” and the image data of gradation “1” are not equal in bit to SF1, and their Hamming distance is “1”.
- the image data of gradation “0” and the image data of gradation “3” are not equal in bits to SF1 and SF2, and therefore their Hamming distance is “2”.
- the Hamming distance between the display gradation and the next higher display gradation is described.
- the next highest display gradation is the lowest display gradation that is lower than the display gradation.
- the right column of the display gradation “247” describes the Hamming distance “3” between the display gradation “247” and the next higher display gradation “245”.
- the first coding table is a coding table in which the hamming distance between adjacent display gradations is large, and the value is any one of “1”, “2”, and “3”, and the average value thereof is “1. 91 ".
- the second coding table is the coding table with the smallest Hamming distance, and its value is “1” and the average value thereof is “1.00”.
- the average value of the Hamming distance between a certain gradation in the coding table with a small number of combinations and the next highest gradation is determined as a certain gradation in the coding table with a large number of combinations and its gradation.
- the first coding table and the second coding table are created so as to be smaller than the average value of the Hamming distance with the next higher gradation.
- the number of gradations that can be displayed is increased and the ability to express an image is improved.
- the power consumption increases because the Hamming distance between adjacent display gradations increases. Become.
- the number of gradations that can be displayed is reduced, so that the ability to express an image is reduced.
- the Hamming distance between adjacent display gradations is reduced, thereby reducing power consumption.
- data is determined by determining an image signal whose image display quality does not deteriorate even if there are few gradations that can be displayed based on a predetermined determination criterion, and selecting a coding table with a small number of subfield combinations for the image signal.
- the power consumption of the electrode drive circuit 42 can be suppressed.
- the signal levels of the image signals of the respective colors are compared, and the image display is performed using the coding table having a large number of gradations that can be displayed for the image signal of the color having a relatively large signal level. Ensure quality.
- a coding table with a small number of subfield combinations is provided. Use to reduce power consumption. In this way, the signal levels of the red image signal sigR, the green image signal sigG, and the blue image signal sigB are compared. For an image signal having a relatively low signal level, a display combination set having a smaller number of combinations than a display combination set used for an image signal having a relatively high signal level is used. This reduces power without sacrificing image display quality.
- the predetermined selection criterion for the red image signal sigR is a ratio between the signal level of the red image signal sigR and the signal level of the green image signal sigG. Therefore, the red image signal sigR whose ratio to the green image signal sigG is smaller than the predetermined constant Kr is used for the red image signal sigR whose ratio to the green image signal sigG is equal to or larger than the predetermined constant Kr.
- a display combination set having a smaller number of combinations than the display combination set is used.
- the first coding table is used for the red image signal sigR.
- the constant Kr is a constant set for the red image signal sigR, and one of “0.8”, “0.75”, “0.7”, “0.65” is set. Each pixel is randomly selected and set as a constant Kr. In this way, a disturbance is added to the selection criterion.
- the predetermined selection criterion for the green image signal sigG is a ratio between the signal level of the green image signal sigG and the larger signal level of the red image signal sigR and the blue image signal sigB. Therefore, for the green image signal sigG whose ratio of the red image signal sigR and the blue image signal sigB to the larger image signal is smaller than the predetermined constant Kg, the red image signal sigR and the blue image signal A display combination set having a smaller number of combinations than the display combination set used for the green image signal sigG having a ratio of SigB to the larger image signal of a predetermined constant Kg is used.
- the red image signal sigR, the green image signal sigG, and the blue image signal sigB are compared, (Condition G1) sigG ⁇ max (sigR, sigB) ⁇ Kg
- the first coding table is used for the green image signal sigG.
- max (A, B) indicates that the larger one of the numerical values A and B is selected.
- the constant Kg is a constant set for the green image signal sigG, and one of “0.3”, “0.25”, “0.2”, “0.15” is set. Each pixel is randomly selected and set to a constant Kg. In this way, a disturbance is added to the selection criterion.
- the predetermined selection criterion for the blue image signal sigB is a ratio between the signal level of the blue image signal sigB and the signal level of the green image signal sigG. Therefore, the blue image signal sigB whose ratio to the green image signal sigG is smaller than the predetermined constant Kb is used for the blue image signal sigB whose ratio to the green image signal sigG is equal to or larger than the predetermined constant Kb.
- a display combination set having a smaller number of combinations than the display combination set is used.
- the constant Kb is a constant set for the blue image signal sigB, and one of “0.8”, “0.75”, “0.7”, and “0.65” is set. Random selection is made for each pixel to obtain a constant Kb. In this way, disturbance is added to the selection criterion.
- the green light emission has the highest luminance compared to the red light emission and the blue light emission, and the visual sensitivity to the gradation is the highest.
- the coding table used for the red image signal sigR is selected by comparing the red image signal sigR and the green image signal sigG, and the blue image signal sigB and The coding table used for the blue image signal sigB was selected by comparing with the green image signal sigG.
- FIG. 6 is a diagram schematically showing the proper use of the coding table of the plasma display device 40 according to Embodiment 1 of the present invention.
- the vertical axis represents the signal level of the red image signal sigR, and the horizontal axis represents the green image signal sigG.
- the signal level is shown.
- the signal level of the blue image signal sigB is set to “0”.
- the image signal satisfying (condition R1) in FIG. 6 has a higher relative signal level of the red image signal sigR than the green image signal sigG, and therefore the first coding table for the red image signal sigR. Is used.
- the image signal that satisfies (Condition R2) uses the second coding table for the red image signal sigR. .
- the four broken lines that separate (Condition R1) and (Condition R2) are the four values “0.8”, “0.75”, “0.7”, and “0.65” of the constant Kr, respectively. It corresponds.
- the second coding is applied to a signal in which the relative signal level is small among the image signals of the respective colors and the display quality of the image does not deteriorate even if the number of displayable gradations is reduced.
- a table is used to reduce power without sacrificing image display quality.
- the constants Kr, Kg, and Kb for determining the magnitude of the signal level of the image signal are set so as to vary stochastically for each pixel. Therefore, the switching boundary of the coding table to be used is randomly spread.
- FIG. 7 is a schematic diagram showing how the coding table is switched with respect to the red image signal sigR in the plasma display apparatus 40 according to the first embodiment of the present invention.
- the region using the first coding table and the second coding table are shown in FIG.
- the area to be used and its boundary are shown.
- the signal level of the green image signal sigG is constant
- the signal level of the red image signal sigR is large on the left side and decreases toward the right side.
- the first coding table is used for pixels indicated by light colors
- the second coding table is used for pixels indicated by dark colors.
- the first coding table is used if (Condition R1) is satisfied, and the second coding table is used if (Condition R2) is satisfied.
- the value of the constant Kr is large, the value obtained by multiplying the green image signal sigG by the constant Kr also increases, so that the region where (Condition R1) is satisfied is narrow, and the region where (Condition R2) is satisfied is wide.
- the value of the constant Kr is small, the region where (Condition R1) is satisfied is wide and the region where (Condition R2) is satisfied is narrow.
- the constant Kr is randomly selected from any one of “0.8”, “0.75”, “0.7”, and “0.65” for each pixel. Then, it is determined that the condition K1 is satisfied for the pixel in the region I regardless of the value of the constant Kr, and light emission or non-light emission is controlled using the first coding table.
- the value of the constant Kr is “0.8” for the pixel in the region II, it is determined that (Condition R2) is satisfied, and the values of the constant Kr are “0.75”, “0.7”, “0” .65 ”, it is determined that (Condition R1) is satisfied. Therefore, for the pixels in region II, the first coding table is used with a probability of 3/4, and the second coding table is used with a probability of 1/4.
- the first coding table is used with a probability of 1/4
- the second coding table is used with a probability of 3/4.
- one of the four numerical values is selected and the constant Kr is set. Therefore, the region I using the first coding table and the region V using the second coding table. Three transition regions II, III, and IV are formed between the two.
- the coding table is smoothly switched by providing a transition region in which the discharge cells that perform light emission or non-light emission control are probabilistically distributed using the respective coding tables at the boundary where the coding tables are switched.
- FIG. 8 is a circuit block diagram showing details of the image signal processing circuit 41 of the plasma display device 40 according to Embodiment 1 of the present invention.
- the image signal processing circuit 41 includes a color separation unit 51, a random number generation unit 52, an R comparison unit 54R, a G comparison unit 54G, a B comparison unit 54B, an R data conversion unit 58R, and a G data conversion unit 58G. And a B data converter 58B.
- the color separation unit 51 separates an input image signal such as an NTSC image signal into three primary color signals, that is, a red image signal sigR, a green image signal sigG, and a blue image signal sigB.
- the color separation unit 51 may be omitted when an image signal of each color is input as the input image signal.
- the random number generator 52 generates a random number for each pixel.
- the random number generated here is a 2-bit binary random number and is “00”, “01”, “10”, or “11”.
- the R comparison unit 54R sets a constant Kr based on the random number generated by the random number generation unit 52, and compares the constant Kr times the green image signal sigG with the red image signal sigR.
- FIG. 9 is a circuit block diagram of the R comparison unit 54R in the plasma display device 40 according to the first embodiment of the present invention.
- the R comparison unit 54R includes a selector 61, a multiplier 62, and a comparator 63.
- the selector 61 selects one of the numerical values “0.8”, “0.75”, “0.7”, “0.65” of the constant Kr based on the random number generated by the random number generator 52. select.
- the multiplier 62 multiplies the green image signal sigG by the constant Kr selected by the selector 61.
- the comparator 63 compares the red image signal sigR with the output of the multiplier 62.
- the R comparison unit 54R outputs a signal indicating which of (Condition R1) and (Condition R2) is satisfied to the R data conversion unit 58R as a comparison result.
- the R data conversion unit 58R includes a coding selection unit 81 and two coding tables 82a and 82b, and controls red image data sigR for red image data dataR, that is, emission or non-emission of red discharge cells. Convert to a combination of subfields.
- the coding selection unit 81 selects one of the two coding tables 82a and 82b based on the comparison result of the R comparison unit 54R. Specifically, the first coding table 82a is selected in an area where (Condition R1) is satisfied, and the second coding table 82b is selected in an area where (Condition R2) is satisfied.
- Each of the coding tables 82a and 82b is configured using a data conversion table such as a ROM, for example, and converts the input red image signal sigR into red image data dataR.
- the G data converter 58G and the B data converter 58B have the same circuit configuration as the R data converter 58R.
- the coding table 82a is the first coding table shown in FIGS. 5A, 5B, and 5C
- the coding table 82b is the second coding table shown in FIG. 5D.
- the display image selected from a plurality of display combination sets based on a predetermined selection criterion.
- a combination set can be used, and a disturbance based on a random number can be added to a predetermined selection criterion.
- each coding table used for each color image signal is selected from two coding tables based on a relative comparison of the signal levels of each color image signal.
- the present invention is not limited to this.
- three or more coding tables may be provided for each color image signal, and one of the three or more coding tables may be selected and used based on the signal level of each color image signal.
- the coding table may be used properly in consideration of other attributes such as image movement.
- a circuit for displaying a gradation that is not included in the display gradation may be added. One example thereof will be described below as a second embodiment.
- each coding table used for each color image signal is selected from four coding tables and used. Further, in addition to the relative signal level of the image signal of each color, it is used for the image signal of each color based on the absolute signal level of the image signal, the spatial difference of the image signal of each color, and the time difference of the image signal of each color. Each coding table is selected.
- 10A, 10B, 10C, 10D, 10E, and 10F are diagrams illustrating a coding table used in the plasma display device 40 according to Embodiment 2 of the present invention.
- 10A and 10B are first coding tables having 90 combinations of subfields, and are the same as the first coding tables shown in FIGS. 5A, 5B, and 5C.
- 10C and 10D are second coding tables having 44 combinations of subfields
- FIG. 10E is a diagram illustrating a third coding table having 20 combinations of subfields.
- FIG. 10F shows a fourth coding table having 11 combinations of subfields, which is the same as the second coding table shown in FIG. 5D.
- the first coding table has the largest hamming distance between adjacent display gradations, and its value is any one of “1”, “2”, and “3”, and the average value thereof is “1.91”. It is.
- the Hamming distance is “1” or “2”, the frequency of “2” is large, and the average value thereof is “1.77”.
- the Hamming distance is “1” or “2”, but the frequency of “2” is almost the same as the frequency of “1”, and the average value thereof is “1.47”.
- the fourth coding table has the smallest Hamming distance, its value is “1”, and the average value thereof is “1.00”.
- the average value of the Hamming distance between a certain gradation in the coding table with a small number of combinations and the next highest gradation is the same as that in a coding table with a large number of combinations. It is set to be smaller than the average value of the Hamming distance with the next higher gradation.
- the data electrode driving circuit 42 is consumed by using a coding table with a small number of subfield combinations for the image signal. Electric power can be suppressed.
- the respective coding tables used for the image signals of the respective colors are determined based on the high visual sensitivity with respect to the gradation.
- the level of visual sensitivity with respect to gradation is determined from the absolute signal level of the image signal of each color, the relative signal level of the image signal of each color, the level of the spatial difference of the image signal, and the level of the time difference of the image signal. be able to.
- the coding table is switched without degrading the image display quality by randomly diffusing the switching boundary of the coding table to be used.
- the absolute signal level of each color image signal, the relative signal level, the magnitude of the spatial difference of the image signal, and the magnitude of the time difference of the image signal will be described in order.
- the predetermined selection criterion regarding the absolute signal level of the image signal is the luminance of the image signal, and either a dark image or a bright image is determined as follows.
- the luminance conversion signal sigY is obtained by multiplying each of the red image signal sigR, the green image signal sigG, and the blue image signal sigB by a coefficient proportional to the luminance.
- sigY 0.2 ⁇ sigR + 0.7 ⁇ sigG + 0.1 ⁇ sigB Then, the luminance conversion signal sigY and the constant BRT are compared, sigY ⁇ BRT If this holds, it is determined as a dark image.
- the constant BRT is set by randomly selecting one of “20”, “18”, “16”, and “14” for each pixel. In this way, a disturbance is added to the selection criterion.
- the predetermined selection criterion regarding the relative signal level of the image signal is the relative signal level with respect to the image signals of other colors, and it is determined whether the signal level is high, the signal level is low, or the signal level is low as follows. To do.
- the red image signal sigR For the red image signal sigR, the red image signal sigR and the green image signal sigG are compared, sigG ⁇ Kr1 ⁇ sigR Is established, it is determined that the signal level is high.
- the constants Kr1 and Kr2 are constants set for the red image signal sigR and are one of “1.6”, “1.5”, “1.4”, and “1.3”. One is randomly selected for each pixel to be a constant Kr1, and one of “0.8”, “0.75”, “0.7”, and “0.65” is randomly selected for each pixel.
- the constant is Kr2. In this way, a disturbance is added to the selection criterion.
- the green image signal sigG For the green image signal sigG, the red image signal sigR, the green image signal sigG, and the blue image signal sigB are compared, max (sigR, sigB) ⁇ Kg1 ⁇ sigG Is established, it is determined that the signal level is high.
- the constants Kg1 and Kg2 are constants set for the green image signal sigG, and one of “0.55”, “0.5”, “0.45”, and “0.4”. One is randomly selected for each pixel to be a constant Kg1, and one of “0.3”, “0.25”, “0.2”, and “0.15” is randomly selected for each pixel. Constant Kg2. In this way, a disturbance is added to the selection criterion.
- the blue image signal sigB the blue image signal sigB and the green image signal sigG are compared, sigG ⁇ Kb1 ⁇ sigB Is established, it is determined that the signal level is high.
- the constants Kb1 and Kb2 are constants set for the blue image signal sigB, and are one of “1.6”, “1.5”, “1.4”, and “1.3”. One is randomly selected for each pixel to be a constant Kb1, and one of “0.8”, “0.75”, “0.7”, and “0.65” is randomly selected for each pixel. The constant Kb2. In this way, a disturbance is added to the selection criterion.
- FIG. 11A and 11B are diagrams showing an example of a display image of the plasma display device 40 according to Embodiment 2 of the present invention and a difference signal of the image, FIG. 11A shows an example of the display image, and FIG. The difference image is shown. A region displayed in white in FIG.
- 11B is a region where the signal level of the differential signal is high, and a coding table with a small number of subfield combinations can be used.
- the area displayed in black is an area where the signal level of the difference signal is low, and a coding table having a large number of combinations of subfields is used for the image signal in this area in order to avoid deterioration in image display quality. It is desirable.
- the predetermined selection criteria for the color image signals of the red image signal sigR, the green image signal sigG, and the blue image signal sigB are the absolute value of the spatial difference with respect to the image signal of that color and the image of that color. It is the ratio of the signal level to the signal level.
- the spatial difference of the image signal is calculated.
- a red differential signal difR (x, y) [ ⁇ sigR (x-1, y) -SigR (x + 1, y) ⁇ 2 + ⁇ sigR (x, y-1) -sigR (x, y + 1) ⁇ 2 ] 1/2 may be calculated and used as a spatial difference.
- the red difference signal difR (x, y)
- the difference component in the horizontal direction is not reflected, but the calculation can be greatly simplified.
- the constant Cr is a constant set for the red image signal sigR, and one of “8.5”, “8.0”, “7.5”, and “7.0” is a pixel. A random number is selected at each time to obtain a constant Cr. In this way, by adding a disturbance to the selection criterion, the coding table is switched while randomly diffusing the boundary where the coding table to be used is switched.
- the constant Cg is a constant set for the green image signal sigG, and one of “8.5”, “8.0”, “7.5”, and “7.0” is a pixel.
- a constant Cg is selected at random every time. In this way, a disturbance is added to the selection criterion.
- the constant Cb is a constant set for the blue image signal sigB, and one of “8.5”, “8.0”, “7.5”, and “7.0” is a pixel. Randomly select every time and set to constant Cb. In this way, a disturbance is added to the selection criterion.
- the time difference of the image signal is calculated.
- FIG. 12 is a diagram showing the proper use of the coding table for the image signal of the plasma display device 40 according to the second embodiment of the present invention.
- the first coding table is used for each of the red image signal sigR, the green image signal sigG, and the blue image signal sigB.
- the image signal determined as a bright image with a high luminance conversion signal sigY is as follows.
- the first coding table is used for each of the red image signal sigR, the green image signal sigG, and the blue image signal sigB.
- the second coding table is set for each of the red image signal sigR, the green image signal sigG, and the blue image signal sigB.
- the fourth coding table is used for the red image signal sigR and the blue image signal sigB having a large relative signal level and a large spatial difference
- the third coding table is used for the green image signal sigG. .
- the third coding table is used for each of the red image signal sigR, the green image signal sigG, and the blue image signal sigB in which the relative signal level of the image signal is medium and the spatial difference is small.
- the fourth coding table is used for the red image signal sigR and the blue image signal sigB where the relative signal level of the image signal is medium and the spatial difference is large, and for the green image signal sigG.
- Each of the third coding tables is used.
- the fourth coding table is used for each of the red image signal sigR, the green image signal sigG, and the blue image signal sigB having a small relative signal level.
- the light emission or non-light emission of the discharge cell is controlled using the coding table having a smaller number of combinations than the coding table used in the region where the relative signal level is large. is doing. Also, in the display image where the gradation change is large, the light emission or non-light emission of the discharge cell is controlled by using a coding table having a smaller number of combinations than the coding table used in the area where the gradation change is small. Yes. Further, in the area where the moving image is displayed, the light emission or non-light emission of the discharge cells is controlled using a coding table having a smaller number of combinations than the coding table used in the area where the still image is displayed.
- Cr, Cg, and Cb are set by changing stochastically for each pixel. Since each of these constants is set by switching at random for each pixel, the switching boundary of the coding table to be used is randomly spread. In this way, at the boundary where the coding table is switched, by providing a transition region in which discharge cells that control light emission or non-light emission using each coding table are probabilistically distributed, the occurrence of the contour of the boundary portion is suppressed. is doing.
- constants Mr, Mg, and Mb for determining either a still image or a moving image have been described as having predetermined values, but the present invention is limited to this. However, these constants Mr, Mg, and Mb may also be set in a stochastic manner.
- FIG. 13 is a circuit block diagram showing details of the image signal processing circuit 141 of the plasma display device 40 according to Embodiment 2 of the present invention.
- the image signal processing circuit 141 includes a color separation unit 51, a random number generation unit 52, a dark image detection unit 153, an R comparison unit 154R, a G comparison unit 154G, a B comparison unit 154B, an R difference unit 156R, A G difference unit 156G, a B difference unit 156B, a motion detection unit 157, an R data conversion unit 158R, a G data conversion unit 158G, and a B data conversion unit 158B are provided.
- the color separation unit 51 and the random number generation unit 52 are the same as the color separation unit 51 and the random number generation unit 52 in the first embodiment.
- the dark image detection unit 153 multiplies each of the red image signal sigR, the green image signal sigG, and the blue image signal sigB by a coefficient proportional to the luminance to obtain a luminance conversion signal sigY. Further, one of the constant BRT candidates “20”, “18”, “16”, and “14” is selected based on the random number generated by the random number generator 52. Then, the luminance conversion signal sigY is compared with the constant BRT, and the comparison result of either the dark image or the bright image is output to the R data conversion unit 158R, the G data conversion unit 158G, and the B data conversion unit 158B.
- the R comparison unit 154R selects one of the candidate numerical values “1.6”, “1.5”, “1.4”, and “1.3” for the constant Kr1.
- the R difference unit 156R selects one of the numerical values “8.5”, “8.0”, “7.5”, and “7.0” for the constant Cr. Select one. Then, the spatial difference of the red image signal sigR is calculated, and the comparison result of either the large spatial difference or the small spatial difference is output to the R data conversion unit 158R using the constant Cr.
- the motion detection unit 157 includes, for example, a frame memory and a difference circuit, calculates a difference between frames as a time difference, and if the absolute value is greater than or equal to a predetermined value, a motion image, and if less than a predetermined value, a still image And the result is output to the R data converter 158R, the G data converter 158G, and the B data converter 158B.
- the R data conversion unit 158R is based on the detection result of the dark image detection unit 153, the comparison result of the R comparison unit 154R, the spatial difference result of the R difference unit 156R, and the motion detection result of the motion detection unit 157, as shown in FIGS.
- the red image signal sigR is converted into red image data dataR using the coding tables shown in 10C, 10D, 10E, and 10F.
- the G data conversion unit 158G converts the green image signal sigG into green image data dataG
- the B data conversion unit 158B converts the blue image signal sigB into blue image data dataB.
- FIG. 14 is a circuit block diagram of R data conversion unit 158R, G data conversion unit 158G, and B data conversion unit 158B of plasma display device 40 in accordance with the second exemplary embodiment of the present invention.
- the R data conversion unit 158R includes a coding selection unit 181, four coding tables 182a, 182b, 182c, and 182d, and an error diffusion processing unit 183.
- the coding selection unit 181 includes four coding tables 182a based on the detection result of the dark image detection unit 153, the comparison result of the R comparison unit 154R, the spatial difference result of the R difference unit 156R, and the detection result of the motion detection unit 157.
- One is selected from 182b, 182c, and 182d.
- Each of the coding tables 182a, 182b, 182c, and 182d is configured by using a data conversion table such as a ROM, and converts the input red image signal sigR into red image data.
- the error diffusion processing unit 183 is provided to display pseudo gradations that cannot be displayed in the coding table.
- the error diffusion processing unit 183 performs error diffusion processing, dither processing, and the like on the red image data, and outputs the result as image data dataR.
- Cg, and Cb are set by varying the probability for each pixel, and the switching boundary of the coding table to be used is randomly diffused.
- the method of randomly diffusing the boundary is not limited to this.
- One example will be described below as a third embodiment.
- the circuit configuration of the image signal processing circuit 241 in the third embodiment is different from the circuit configuration of the image signal processing circuit 141 in the second embodiment in the circuit configuration of the R comparison unit 254R, the G comparison unit 254G, and the B comparison unit 254B. is there.
- FIG. 15 is a circuit block diagram of the R comparison unit 254R of the plasma display device 40 according to the third embodiment of the present invention.
- the R comparison unit 254R includes subtracters 261b, 261c, 261d, a multiplier 262, comparators 263a, 263b, 263c, 263d, comparators 265b, 265c, 265d, AND gates 266b, 266c, 266d, OR A gate 267; a multiplier 272; comparators 273a, 273b, 273c, 273d; AND gates 276b, 276c, 276d; and an OR gate 277.
- the subtractor 261b subtracts “10” from the red image signal sigR, the subtractor 261c subtracts “20” from the red image signal sigR, and the subtractor 261d subtracts “30” from the red image signal sigR. Output each.
- the multiplier 262 multiplies the green image signal sigG by a constant Kr1.
- the comparator 263a compares the red image signal sigR with the constant Kr1 times of the green image signal sigG.
- the comparator 263b compares the signal obtained by subtracting “10” from the red image signal sigR and the constant Kr1 times the green image signal sigG.
- the comparator 263c compares the signal obtained by subtracting “20” from the red image signal sigR and the constant Kr1 times the green image signal sigG.
- the comparator 263d compares a signal obtained by subtracting “30” from the red image signal sigR and a constant Kr1 times the green image signal sigG.
- the comparator 265b compares the random number generated by the random number generator 52 with the numerical value “1”.
- the random number is “00”, “01”, “10”, or “11” in 2-bit binary, that is, “0”, “1”, “2”, or “3” in decimal notation. . Therefore, the probability that the output of the comparator 265b is “H” is 3/4, and the probability that the output is “L” is 1 ⁇ 4.
- the comparator 265c compares the random number generated by the random number generation unit 52 with the numerical value “2”. Therefore, the probability that the output of the comparator 265c is “H” is 1 ⁇ 2, and the probability that it is “L” is 1 ⁇ 2.
- the comparator 265d compares the random number generated by the random number generator 52 with the numerical value “3”. Therefore, the probability that the output of the comparator 265d is “H” is 1 ⁇ 4, and the probability that the output is “L” is 3/4.
- the AND gate 266b outputs a logical product of the output of the comparator 263b and the output of the comparator 265b
- the AND gate 266c outputs a logical product of the output of the comparator 263c and the output of the comparator 265c
- the AND gate 266d The logical product of the output of the comparator 263d and the output of the comparator 265d is output.
- the OR gate 267 outputs a logical sum of outputs from the AND gates 266b, 266c, and 266d.
- the multiplier 272 multiplies the green image signal sigG by a constant Kr2.
- Comparators 273a, 273b, 273c, 273d, AND gates 276b, 276c, 276d, and OR gate 277 have corresponding comparators 263a, 263b, 263c, 263d, AND gates 266b, 266c, 266d, OR The same as the gate 267.
- FIG. 16 is a schematic diagram showing how the coding table is switched in the plasma display device 40 according to the third embodiment of the present invention, and is a schematic diagram corresponding to FIG. 7 in the first embodiment.
- the signal level of the green image signal sigG is constant
- the signal level of the red image signal sigR is large on the left side and is displayed as the image signal decreases toward the right side.
- the comparator 263a compares the red image signal sigR with “1.5” times the green image signal sigG, determines that the signal level is high in the regions I, II, III, and IV, and sets “H”. It is determined that the signal level is in the region V and “L” is output. Since the comparator 263b compares the signal obtained by subtracting “10” from the red image signal sigR and “1.5” times the green image signal sigG, the region where the signal level is determined to be large is narrowed. Therefore, “H” is output in the regions I, II, and III, and “L” is output in the regions IV and V.
- the comparator 263c compares the signal obtained by subtracting “20” from the red image signal sigR and “1.5” times the green image signal sigG, the region for determining that the signal level is large is further narrowed. “H” is output in region II, and “L” is output in region III, region IV, and region V. Since the comparator 263d compares the signal obtained by subtracting “30” from the red image signal sigR and “1.5” times the green image signal sigG, it outputs “H” in the region I, and outputs the region II, region “L” is output in III, region IV, and region V.
- the output of the comparator 265b is “H” with a probability of 3/4 and “L” with a probability of 1/4.
- the output of the comparator 265c is “H” with a probability of 2/4 and “L” with a probability of 2/4.
- the output of the comparator 265d is “H” with a probability of 1/4 and “L” with a probability of 3/4.
- the determination result of the R comparison unit 254R is determined to be in the signal level for the pixels in the region V regardless of the random number value.
- the signal level is medium with a probability of 3/4 and the signal level is determined to be high with a probability of 1/4.
- the signal level is medium with a probability of 1/2, and the signal level is determined to be high with a probability of 1/2.
- the signal level is medium with a probability of 1/4, and the signal level is determined with a probability of 3/4.
- the disturbance is added to the signal level of the image signal of each color.
- three transition regions II, III, and IV are formed between the region I that uses the first coding table and the region V that uses the second coding table. In this way, by providing a transition region in which discharge cells that perform light emission or non-light emission control using each coding table are probabilistically distributed at the boundary where the coding table is switched, the coding table can be switched smoothly.
- the present invention is not limited to this, and a configuration in which a plurality of other coding tables are used by switching. Good.
- the number of subfields and the luminance weight of each subfield are not limited to the above values, and the specific numerical values used in the above embodiments are merely examples. However, it is desirable to set the optimal value as appropriate in accordance with the characteristics of the panel, the specifications of the plasma display device, and the like.
- the present invention is useful as a driving method for a plasma display device.
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Abstract
Description
以下、本発明の実施の形態におけるプラズマディスプレイ装置について、図面を用いて説明する。図1は、本発明の実施の形態1におけるプラズマディスプレイ装置のパネル10の構造を示す分解斜視図である。ガラス製の前面基板21上には、走査電極22と維持電極23とからなる表示電極対24が複数形成されている。そして、表示電極対24を覆うように誘電体層25が形成され、その誘電体層25上に保護層26が形成されている。背面基板31上にはデータ電極32が複数形成され、データ電極32を覆うように誘電体層33が形成され、さらにその上に井桁状の隔壁34が形成されている。そして、隔壁34の側面および誘電体層33上には赤色に発光する蛍光体層35R、緑色に発光する蛍光体層35Gおよび青色に発光する蛍光体層35Bが設けられている。
(条件R1)sigR≧sigG×Kr
が成り立つ領域では、赤の画像信号sigRに対して第1のコーディングテーブルを用いる。
が成り立つ領域では、赤の画像信号sigRに対して第2のコーディングテーブルを用いる。
(条件G1)sigG≧max(sigR,sigB)×Kg
が成り立つ領域では、緑の画像信号sigGに対して第1のコーディングテーブルを用いる。ここでmax(A,B)は、数値A、Bのうち大きいほうを選択することを示している。
が成り立つ領域では、緑の画像信号sigGに対して第2のコーディングテーブルを用いる。
(条件B1)sigB≧sigG×Kbが成り立つ領域では、青の画像信号sigBに対して第1のコーディングテーブルを用いる。
パネルの構造、電極に印加する駆動電圧波形等については実施の形態1と同様であるので説明を省略する。実施の形態2においては、各色の画像信号に対して用いるそれぞれのコーディングテーブルを、4つのコーディングテーブルの中から選択して使用している。また各色の画像信号の相対的な信号レベルに加えて、画像信号の絶対的な信号レベル、各色の画像信号の空間差分、各色の画像信号の時間差分に基づき、各色の画像信号に対して用いるそれぞれのコーディングテーブルを選択している。
そして輝度換算信号sigYと定数BRTとを比較して、
sigY<BRT
が成り立てば暗画像と判定する。
が成り立てば明画像と判定する。
sigG×Kr1≦sigR
が成り立てば、信号レベル大と判定する。
が成り立てば、信号レベル中と判定する。
が成り立てば、信号レベル小と判定する。
max(sigR,sigB)×Kg1≦sigG
が成り立てば、信号レベル大と判定する。
が成り立てば、信号レベル中と判定する。
が成り立てば、信号レベル小と判定する。
sigG×Kb1≦sigB
が成り立てば、信号レベル大と判定する。
が成り立てば、信号レベル中と判定する。
が成り立てば、信号レベル小と判定する。
例えば、表示画面上の画素の位置(x、y)における赤の画像信号sigR(x、y)に対して、赤の差分信号
difR(x、y)=[{sigR(x-1、y)-sigR(x+1、y)}2+{sigR(x、y-1)-sigR(x、y+1)}2]1/2を算出し空間差分としてもよい。緑の差分信号difGおよび青の差分信号difBについても同様である。
difR(x、y)=|sigR(x、y-1)-sigR(x、y)|を算出して空間差分とした。この算出方法によれば水平方向の差分成分は反映されないが、計算を大幅に簡略化することができる。緑の差分信号difG(x、y)、青の差分信号difB(x、y)についても同様である。
difB(x、y)<sigB(x、y)/Cbが成り立てば、空間差分小と判定する。
movR(x、y、t)=|sigR(x、y、t-1)-sigR(x、y、t)|として時間差分を算出することができる。緑の差分信号movG(x、y、t)、青の差分信号movB(x、y、t)についても同様である。
movB(x、y、t)≧sigB(x、y、t)/Mbのいずれかが成り立てば動画と判定し、いずれも成り立たなければ静止画と判定する。
実施の形態3における画像信号処理回路241の回路構成が実施の形態2における画像信号処理回路141の回路構成と異なる点は、R比較部254R、G比較部254GおよびB比較部254Bの回路構成である。
22 走査電極
23 維持電極
24 表示電極対
32 データ電極
40 プラズマディスプレイ装置
41,141,241 画像信号処理回路
42 データ電極駆動回路
43 走査電極駆動回路
44 維持電極駆動回路
45 タイミング発生回路
51 色分離部
52 乱数発生部
54R,154R,254R R比較部
54G,154G,254G G比較部
54B,154B,254B B比較部
58R,158R Rデータ変換部
58G,158G Gデータ変換部
58B,158B Bデータ変換部
61 セレクタ
62 乗算器
63,263a,263b,263c,263d,265b,265c,265d,273a,273b,273c,273d 比較器
81,181 コーディング選択部
82a,82b,182a,182b,182c,182d コーディングテーブル
153 暗画像検出部
156R R差分部
156G G差分部
156B B差分部
157 動き検出部
183 誤差拡散処理部
261b,261c,261d 減算器
262,272 乗算器
266b,266c,266d,276b,276c,276d ANDゲート
267,277 ORゲート
sigB 青の画像信号
sigG 緑の画像信号
sigR 赤の画像信号
Claims (6)
- 1フィールド期間をあらかじめ輝度重みの定められた複数のサブフィールドで構成するとともに、前記サブフィールドの任意の組合せの中から複数の組合せを選択して表示用組合せ集合を作成し、前記表示用組合せ集合に属するサブフィールドの組合せを用いて放電セルの発光または非発光を制御して階調を表示するプラズマディスプレイ装置の駆動方法であって、
組合せの数の異なる複数の表示用組合せ集合を備えるとともに、乱数を発生する乱数発生部を備え、
赤の画像信号、緑の画像信号、青の画像信号のそれぞれに対して、複数の前記表示用組合せ集合の中から所定の選択基準に基づき選択した表示用組合せ集合を用いるとともに、
前記乱数に基づく擾乱を前記所定の選択基準に付加することを特徴とするプラズマディスプレイ装置の駆動方法。 - 前記赤の画像信号に対する前記所定の選択基準は、前記赤の画像信号の信号レベルと前記緑の画像信号の信号レベルとの比であることを特徴とする請求項1に記載のプラズマディスプレイ装置の駆動方法。
- 前記緑の画像信号に対する前記所定の選択基準は、前記緑の画像信号の信号レベルと前記赤の画像信号および前記青の画像信号の大きいほうの信号レベルとの比であることを特徴とする請求項1に記載のプラズマディスプレイ装置の駆動方法。
- 前記青の画像信号に対する前記所定の選択基準は、前記青の画像信号の信号レベルと前記緑の画像信号の信号レベルとの比であることを特徴とする請求項1に記載のプラズマディスプレイ装置の駆動方法。
- 前記赤の画像信号、前記緑の画像信号、前記青の画像信号のそれぞれの色の画像信号に対する前記所定の選択基準は、その色の画像信号に対する空間差分の絶対値とその色の画像信号の信号レベルとの比であることを特徴とする請求項1に記載のプラズマディスプレイ装置の駆動方法。
- 組合せの数の少ない表示用組合せ集合におけるある階調とその次に高い階調とのハミング距離の平均値は、組合せの数の多い表示用組合せ集合におけるある階調とその次に高い階調とのハミング距離の平均値よりも小さいことを特徴とする請求項1に記載のプラズマディスプレイ装置の駆動方法。
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US12/812,465 US8400373B2 (en) | 2008-12-11 | 2009-12-10 | Driving method of plasma display device |
KR1020107018050A KR101062573B1 (ko) | 2008-12-11 | 2009-12-10 | 플라즈마 디스플레이 장치의 구동 방법 |
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JP5585232B2 (ja) | 2010-06-18 | 2014-09-10 | ソニー株式会社 | 固体撮像装置、電子機器 |
WO2012098887A1 (ja) * | 2011-01-20 | 2012-07-26 | パナソニック株式会社 | 画像表示装置および画像表示装置の駆動方法 |
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CN101960507B (zh) | 2013-03-27 |
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